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Atthetimeofthiswriting(2014),thesunspotcyclehadpassedapeakthatwaslessintensethantheseveralpeaksthatprecededit.Theamountofnoisethatthefrontendgeneratesalsomattersbecausesubsequentstagesamplifyitsnoiseoutputaswellasitssignaloutput.Thenhopin,andforawhile,letyourlifebecomeascenarioof“monkeysee,monkeydo,monkeybefast”!YouBetheHunterIfyourstationhasmodestantennasand/orlacksafull-legal-limitamplifier,you’llfinditdifficultto“holdafrequency”inacontest.Someoftheproblemswithladderlineandopenwireareovercomebysocalledtubularline.Ifyoutuneyourradiotofrequenciesafewkilohertzabovethe“standard”PSK31bandsonHF,you’llhearsignalsthatsoundlikeslowversionsofMFSKorPSK—andthat’sexactlywhattheyare,withaspecialtimesynchronizationfeatureandslowspeedtodrasticallyimprovethesignalto-noiseratio,evenoverCW,byasmuchas10dBaccordingtoitsproponents.Ifthetransmitterandthereceiveraremorethanafewkilometersapart,thepathloss(thedifficultywithwhichsignalspropagatebymeansofsurface-wavesorwaveguidemode)increasesasthefrequencygoesup.Ifyou’vejustjoinedour“fraternity,”congratulationsongettingyourlicense,andwelcometothefray.SomehamsliketobuildalloftheirFAXequipmentfromscratch.Youshouldagaingetareadingof0.Second,Idon’tletanycordsplicesorothersensitiveelectricalpointsliedirectlyonthefloor.•Acquireaportable2-meterFMtransceiverattheveryleast,andifpossible,adual-bandFMradiothatworkson2metersand70centimeters.ForNerdsOnlyYoucanhearthesfericsfromadistantthundershoweronthestandardAMbroadcastband.Theelectricalpowerthatcomesoutofageneratorisalwayslessthanthemechanicalpowerrequiredtodriveit.Checkthemeterreading.UpperFloorsIfyouputyourstationonafloorabovegroundlevel,thenyou’llhavetroublemakingthegroundschemeofFig.1-4(underthesmallerhamtransceiver)canbehadforahundreddollarsorsoatRadioShackstoresandvariousotherlargegeneralretailoutlets.Ifyouplantouseaminimumamountofpowerforyourstation,youwon’tneedtoworryaboutallthatelectricalbusiness.Thisbandgetsalotofuse;broadcasterslikeitbecauseitpracticallyguaranteesalargelisteningaudience.•Chapter1explainswhatradiowavesareandhowtheytravel.On/offkeyedMorsecodeworksthebest,asdoesasynchronizeddigitalmodethatusesslow,preciselytimed,multiple-frequencyshiftsandgoesunderthegeneralmonikerofWSJT.Inaddition,suchanantennacanhavealowprofileifyouusesmallgaugewire.Abbreviations:HF=highfrequency(3MHzto30MHz);VHF=veryhighfrequency(30MHzto300MHz);UHF=ultrahighfrequency(300MHzto3GHz).•TheIFstagesproducemostofthegain(amplification)inasuperhetreceiver.Engineersdefinethebandwidthofanymodulatedsignalasthedifferencebetweenthemaximumandminimumfrequenciesthatthesignalcontains.LaterIreplacedtheSWRmeterwiththetransmatchshowninFig.SmallGasoline-PoweredGeneratorsAdvancedsmall-scalegeneratorscircumventtheneedforconstantmotorspeedbyconvertingthegeneratedACtoregulatedDC,andthenusingapowerinvertertogenerateACfromthatDC.ThesameholdstrueforFSKandPSKmodes.Thereceivermustbeprogrammedwiththissamelist,inthesameorder,andmustbesynchronizedwiththetransmitter.ABBSletsyouuseamodemtoconnectyourcomputertotheInternet—ortoahampacketradionetwork,inwhichcaseyouhaveapacketradiobulletin-boardsystem(abbreviatedPBBS)—andleavemessagesforotherusers,justasyouwoulddowithpaperandthumbtacksonanold-fashionedbulletinboard.Onceinawhile,you’llhearbothstationsatthesametime,competingwitheachother!AllocationsbyModeYoumayuseUSBmodeforvoice(notLSB),aswellasthecommondigitalmodes,suchasCW,RTTY,PSK,on60meters.TheJpoleoffersalow-costalternativetometal-tubing,verticalantennasatfrequenciesfromapproximately10MHzupthrough300MHz.Ineffect,theJ-poleisahalfwavelengthverticalantennafedwithanimpedancematchingsectioncomprisingaquarter-wavelengthsectionoftransmissionline.Anidealvoiceaudiobandpassfilterhaslittleornoattenuationwithinthepassbandrangebuthighattenuationoutsidethepassbandrange,alongwithanearrectangularresponsecurve.Inaddition,thefirstfloorsofhomeshavewindows,soyoucaneasilyrunyourfeedlines,groundwires,andcontrolcablesoutside!Ifyoucanmanagetogetyouroperatingdeskortableunderneathawindow,you’llhavethebestofeverything.Mostrectifierdiodesaremadefromsilicon,soengineerscallthemsiliconrectifiers.Aheavy-dutyUPS(outofthepicturetotheright)servestwopowerstripsmountedonametalbakingsheetthatrestsondetachedplasticshelves.TABLE8-4AbbreviationsusedinCWoperation.1-5A,accordingtothewavelengthinmeters(m).YoumightwanttokeepacomputerononeoftheInternetradarsitessothatifastormapproachesorrapidlydevelops,youcan“see”itcoming.AnOldTimerRemembersDuringtheearlyandmid1970swhenIattendedcollege,Igotinterestedinhigh-speedCW(alsocalledQRQ,whichliterallytranslatesto“Let’sgofaster”).YoucanalsodoanInternetsearchonthephrase“greatcirclemap”andtakeitfromthere.Iliketwoinparticular:DigiPanandHamScope.Thewholesignalthereforeroamsupanddowninfrequencywithinadefinedrange.TheoperatorofthedestinationstationmustcheckthePBBSbeforeheorshecangetthemessage.Frenzel,LouisE.,Jr.,ElectronicsExplained.Onceinawhile,however,anerrorwilloccurandtheresultingsignalwillstilladheretothe4:3rule;inthatcase,you’llgetamisprint.CommoncircuitsincludetheenvelopedetectorforAM,theproductdetectorforSSB,FSK,andCW,andtheratiodetectorforFMandPM.Thesimplestparallel-wiretransmissionlineisopenwire.OnCW,youcanrespondneartheDXstation’sfrequency,say200Hzto500Hzhigherorlower,andconsiderthemodeassingle-frequency.AspecializedconductornetworkcalledacounterpoisecanprovideanRFgroundwithoutadirectearth-groundconnection.Ifthefieldsarestrongerinsomeplanesthaninothers,thatistosay,iftheirstrengthsdependfrominstanttoinstantontheirslant,youhaveellipticalpolarization.What’sTrueQRP?Onescaleandneedleindicateforwardpower;asecondscaleandneedleindicatereflectedpower;athirdscale,calibratedaccordingtothecrossingpointofthetwoneedles,indicatestheSWR.Inmyopinion,iftheARRLsaysthataproductisgood,thenit’sgottobegood!LadderlineworkswellforresidentialTVreceptionusingold-fashionedoutdoorantennasinfringeareasbecausethislinehaslowerlossperunitoflength,thansolid-dielectriclines.Thenuseastanding-wave-ratio(SWR)meterandadiagonalcuttertotrimtheantenna,bitbybitfromeachend,untilthelowestSWRoccursatthefrequencyyoumostoftenuse(oratthecenterofthebandifyoudon’thaveanyparticularfrequencypreference).Onthelowerbands,FSTVsignalsaresimply“toobig.”Forexample,theentire2-meterhambandisonly4MHzwide,notevenenoughforoneFSTVsignal.Itconsistsoftwowiresparalleltoeachother,withthefewestpossiblenumberofinterveningsupports.Themaximum(reference)amplitudeof0dBrepresents1milliwattofpower,aconditionthatengineersabbreviateas0dBm(0decibelsrelativeto1milliwatt).Sfericswillgiveyoufarlessgriefherethanonlowerbands.InanAMsignal,youcanexpressthemodulationextentasapercentagerangingfrom0%,representinganunmodulatedcarrier,to100%,representingthemaximumpossiblemodulationyoucangetwithoutintroducingdistortionintothesignal.Forcompactnessandconvenience,andalsotoincreasetheloopinductance,alengthofinsulatedorenameledwirecanbewoundaroundarod-shapedinductorcoremadeofpowderediron.Asimplewirereceivingantenna,whichisallyouneedtoreceivethesignals,costspracticallynothing.Thislittlegadgeteliminatestheneedfortransmittingsignalsovertheairwaves.Theradiusofreliablerepeatercoveragecanexceed100kilometerswhenallthesefactorsareoptimized.Youcanfigureouthowwellareceiverperformsinthisrespectbylookingattheshapefactorspecification(page152)or,betteryet,testingaradioinrealtime.Additionaldirectorscanbeaddedtothebasicthree-elementquaddesigntoformquadshavinganydesirednumbersofelements.Ifdesired,thecomputercanalsocontroltheantennasforthestation,andcankeepalogofallstationsthathavebeencontacted.SomehamshaveusedsurpluscommercialFAXapparatustobuildtheirFAXstations.17.Here’sabreakdownofthecomponentsinatypicalpowersupplyofthesortusedwithfixed-stationhamradiotransceiversthesedays,alongwithalittle“insideinformation”abouthowtheywork.TheTUalsogeneratesthesignalsnecessarytosendRTTYwhenanoperatortypesonakeyboard.Thefeed-pointimpedanceofthefoldeddipoleisapureresistanceofapproximately290ohms,orfourtimesthefeed-pointresistanceofahalf-waveopendipolemadefromasinglewire.Thetransformer’sphysicalsizeandmassdependontheamountofcurrentthatyouexpectittodeliver.FIGURE2-6Approximategraphshowingthesunspotcyclesthathavetakenplacesince1920.Fast-ScanTelevisionAmateurfast-scantelevision(FSTV)signalsarejustlikeold-fashionedanalogTVbroadcastsignals,exceptthathamsuselesstransmitterpowerthanbroadcastersdid!AnanalogFSTVsystemprovides30images,orframes,persecond.YoucandisabletheVOXandusePTTinsteadifyoupreferthatmethod.Inarepeaterenvironment,“breakingin”isusuallyokayunlesstheongoingcommunicationhasapriorityorisforanemergency.TheTNCalsotakespacketsfromtheradioreceiver,andputsthemintheproperformatfordisplayand/orstorageonthecomputer;that’sanalog-to-digital(A/D)conversion.Impulsenoisetendstogetworseasthefrequencygoesdown,andcanplagueAMbroadcastreceiverstotheconsternationoftheirusers.Someharmonicsoccur,andiftheygetintoyourSSBtransmittingpassband,they’llshowupassecondarysignalsontheair.Theoptimumspacingbetweentheelementsofadrivenelement/directorYagiis0.1to0.2wavelength,withthedirectortuned5%to10%higherthantheresonantfrequencyofthedrivenelement.Asoneofthebestall-aroundlong-rangecommunicationbands,20metersprobablyconstitutesthesinglemostpopularspanoffrequenciesallocatedtoradiohamstoday.Time“flows”downwardacrossthewholescreen.•Failingtoyieldafrequencytoanemergencyoperation.Themoretimethatyouallowforsendingtheimage,thebettertheresolutionyou’llget.Inmanycases,onestationwillcomeinbetterthantheother,sothe“tweets”willalternatebetweenstrongandweak.Whentheshieldofthecableiswellgrounded,itkeepsthedatasignalsfrom“leaking”outofthecable.Ifthenodesarewidelyseparated,satelliteorHFlinksareused.Sucharegulatorchipgoesinthepower-supplycircuitattheoutputofthefilter.Whenyouwanttotransmit,youcanhitabuttonmarked“T/R”onacontrolbaratthetopofthescreen.Thecompletespanoffrequenciescoversmorethananorderofmagnitude(factorof10),thatis,thetopfrequencyon11metersisalittlemorethan10timesthelowestfrequencyon120meters.InFig.7-14A.ListenaroundontheSSBportionsoftheHFbandsforawhile,andyou’llgraduallygrowfamiliarwiththejargonandquirkspeculiartothishobby!OperatinginFMMosthamFMoperationtakesplaceontheVHFandUHFbands,especially2metersand70centimeters.Nevertheless,you’llalwayswanttoensurethatyourrighasasubstantialelectricalground,sothatyoudon’tgetashockfrommetallicpartsintheeventofashortcircuitintheequipmentsomewhere.Mydadintroducedmetootherhobbiesasidefromradio;hewasthesortoffathereverykidshouldhave,encouragingmetofindandchasemyowninterests.Inthecontextofanantennaarray,thetermparasiticdescribesthecharacteristicsofcertainantennaelements.Characteristicsofalid,someofwhicharemerelyrudeandothersofwhichactuallyviolateFCCregulations,include:•FailingtoaskifafrequencyisinusebeforesendingaCQ.AllocationsbyLicenseClassAnyonewhoholdsanExtra,Advanced,orGeneralclasslicensemayuseanychannelinthe60-meterband,keepinginmindtherestrictionsoutlinedabove.1-19.However,hamFAXisdonebymeansofradio,oftenatHF,wheretheionosphereintroducesphasemodulationandfading,andwhereatmosphericandhumanmadenoiseandinterferencecommonlyoccur.You’llfindplentyofinformationabouttheirbroadcastformatonthatsite.Ifyousee0astheresultforstep7,switchthemetertothenextlowerACvoltagefunctionandrepeatthetest.AmateurTeleprintingoverRadioInhamradiopractice,thefirstmodetotakeadvantageofARQhandshakingforerrorcorrectionbecameknownasamateurteleprintingoverradio(AMTOR).Atmicrowavefrequencies,largedishantennascanhaveforwardgainfiguresthatexceed35dBd.That’sapowergainof37to1ormore!Ifyoufeedsuchadishwiththemaximumlegallimitof1500watts,youcantheoreticallygetanERPof1500×37=55,000watts,comparabletoalargebroadcaststation’stransmitteroutput!Don’tstandinfrontofsuchamonsterwhenit’stakingpower;theenergycomingoutofitcancookyourinsidesasifyouwerethecontentsofamicrowaveoven.Lookfortransequatorialsporadic-EopeningsinMarch,April,September,andOctober.(Instubborncases,thenoiseblankercan’tdealwiththeenergypulses,andyouhavetorelyonalimiterinstead.)Thepulsesofignitionnoiseareofveryshortduration,althoughtheirpeakintensitycanbeconsiderable.Onepossiblemeansofdefenseisprovidedbyequipmentforprotectionagainstdirectlightninghits.Youcan’texpecttogetanefficientHFmobileantennainmostsituationswithordinarycars.Ofcourse,suchcommunicationshavetotakeplaceinaline-of-sightmode—literally!CharacteristicsTroposometimeshappenson1.25metersand70centimeters,andrarelyonbandsathigherfrequencies.FIGURE3-4CloseupoftheMMTTYtuningscopes.TuninginaSignalYetanotherdistinctionbetweenCWandnon-CWdigitaltextinvolvesthetuningprocedure.Onceinawhileyou’llfindsomeonewalkingaroundwithamoresubstantialradio,suchastheYaesuFT-857Dandasmall,lightbatteryinabackpack,butsuchoperationsaregenerallyconfinedtoVHFandUHFbecauseofantennaconstraints.Asabandbecomesoccupiedwithanincreasingnumberofspread-spectrumsignals,theoverallnoiselevelinthebandappearstoincrease.WhileFMisavoicemodelikeSSB,you’llbehavedifferentlyonanFMrepeaterthanyouwouldinanHFSSBenvironment.Ifso,youneedamorerobustelectricalsupply!Ifyouwanttogetmoretechnical,youcanactuallyhookupanACvoltmetertoyoursystemandwatchitsreadingasyoukeytherigonandoff.Thenyoumeasurethesignallevel,inmicrovolts,attheantennaterminals.Butexceptionsoccur,notablyon30metersand20meters.TipInChap.Thiscontraptioncomprisesanoninductiveresistorwithapowerdissipationratinghighenoughtoconvertallofyourtransmitter’sRFenergytoheatwithoutburningup.Someradiohams,myselfincluded,havebuiltmodulated-lighttransmittersandreceivers,communicatingoverdistancesrangingfromafewmeterstoafewkilometers.Iwon’tattempttomakeanyproductcomparisonsorrecommendationshere.Nonlinearitycancauseunwantedmixingamongmultipleincomingsignals.Nevertheless,QRPmobilehasplentyofassets,andforhamswhoenjoyQRP,thetechnicalchallengesconstituteagoodreasontogothisroute!•Yourradioplaceslittleornostrainonyourvehicle’selectricalsystemifyourunQRP,evenifyoutransmitinamodethatinvolvescontinuouscarrieroutput,suchasFM.That’sanengineeringcompromise.OnlyaprimitivetransmittereverputsoutaCWtonewithqualityanythinglessthan9.ThetransmittermustworkhardertoaccomplishnegativePWMthantoproducepositivePWMbecauseithastotransmitasignalforalargerproportionofthetimeontheaverage.Duringtimeswhenthesunspotactivityincreases,conditionsimproveonthisband,andpathswillsometimesworkevenwhentheyliemostlyorentirelyonthedarksideoftheplanet.(IhavethecontrolbardisabledintherenditionshowninFig.ThepeakclippingproducesRFemissionsoutsidethenormalSSBpassband.ThisarrangementminimizesRFgroundloss,althoughthecounterpoisewon’tprovideagoodelectricalgroundunlessconnectedtoagroundroddrivenintotheearth,ortotheutilitysystemground.AnOldTimerRemembersAsateenagehaminthe1960sandearly1970s,myfavoritecontestwastheARRLFieldDay,heldonthelastfullweekendinJune.TheselinesrepresentEMenergycomponentsatspecificfrequencies.Itkeepsthedesiredsignalsinsideitself,andkeepsoutunwantedsignalsandinterference.Ifyoueverseeanymeterreadingotherthan0fortheconditionbetweenthetwo“thirdholes,”youknowthatyouroutletdoesnothaveagoodground.That’smoredifficultforbelow-groundstations,obviously,thanforabove-groundstations.YoucangetagoodclueastotheconditionsbetweenColoradoorHawaiiandyourlocationon20metersbysettingyourradioto15.000MHzandlisteningforWWVand/orWWVH.Inthiscase,RRisafunctionoftheoverallconductorlengthinwavelengths.•Thedetectorextractstheinformationfromthesignal.Groundingisimportantforacoaxialcabletofunctionproperly.YouBethePreyWhenyouhaveawell-engineeredantennasystemandafull-legal-limitamplifier,you’llbeableto“runafrequency”inacontest,sometimesforquiteawhile.IdownloadedthePDFversionandprinteditforpermanentreference(oratleastuntilthenextchangeinofficialspectrumallocations).YoucanalsofindoutaboutpropagationconditionsbetweenHawaiiandyourlocationbylookingoutforWWVHonthesamefrequency.Thisdesignattributeminimizeslinelossperunitoflength,andreducestheeffectsofwettingoricingontheZo.Topreventwaterfromcollectinginsidethetube,youcanpunchacoupleofsmallholesinthecylinderatphysicallowpoints,sothatanywaterthatmightcollectinsidethelinecanrunout.AllocationsbyModeOnlythedigitalmodes(RTTY,PSK,MFSK,data,andCW)areallowedbetween28.000MHzand28.300MHz.From28.300MHzto29.700MHz,youcanusevoiceandimagingemissions.Well-sentcodesoundsrhythmic,almostmesmerizing,toatrueCWbuff.16.Tuneyourreceiversothatthemarksignalproducesanaudiotoneof2125Hzandthespacesignalproducesanaudiotoneof2295Hz,representinga170-Hzshift.TheF1layer,normallypresentonlyonthedaylightsideoftheearth,formsatabout200kilometersaltitude;theF2layerexistsatabout300kilometersovermost,orall,oftheearth,onthenighttimesideaswellasthedaylightside.Neverreciprocateinkind;maintainyourcourtesynomatterhowrottensomebodyelsegets.Let’scallthemheavyportableandlightportable.TheARRLpublishesexcellentbooksthatdealwithallsubjectsrelevanttohamradio,aswellasup-to-datelicenseexamstudymaterials.Ifyouplacefourhelicalsatthecornersofasquareandfeedthemallinphase,forexample,youcangetanextra6dBofforwardgain(afourfoldincreaseinERPworksoutto6dB).However,attimesofpeaksunspotactivity,worldwidecommunicationispossibleonthisband,afeaturethatbringsbothgoodandbadconsequences.(SomeCWoperatorsusedecodingsoftwareandkeyboardkeyers,butdie-hardslikemestilldoittheoldway.)Youcancarryonanon-CWdigitaltextQSOinanoisyroomwithoutheadphones;onCWyou’dneedheadphonesinthatsamenoisyroom.Forexample,ifsomeonecan’tgetmynamestraight(Stan),thinkingmaybeit’sDanorSam,Icanspellitoutforthem.TheVOXmodeeliminatestheneedforthrowingaswitchorpressingabuttontochangefromreceivemodetotransmitmode.Bytheway,ifyouplantoprintthisdocument,getyourprinterreadytodosomehardwork.Thatistosay,they’reallequallywide.MoreserioushamsgofortheGeneralClasslicenseortheAmateurExtraClasslicense.Allyouneedisanaudiocordtoconnectyourradio’saudiooutput(fromtheheadphonejackorfromanauxiliaryconnectorontherearpanelsofsomeradios)tothe“linein”jackonyourcomputer,alongwithoneoftheseveralRTTYprogramsavailabletoday.Toconfirmreceiptoftheotherstation’sdata,say“QSL.”Ifyoumustasksomeonetorepeatcertaindata,requestinplainlanguagethattheysenditagain.TechnicianMostnewhamsholdTechnicianlevellicenses.EngineerscallthispointintheLFbandthemaximumusablelowfrequency(MULF).ForSSBvoicewithoutcompressionorclippingorotherprocessing,theratiohoversaround25to33percent.HeadsUp!Inathree-wireelectricalutilitysystem,thegroundprongontheplugshouldneverbedefeatedbecausesuchmodificationcanresultindangerousvoltagesappearingonexposedmetalsurfaces.Inhi-fimusicbroadcasting,andinsomeotherapplications,suchashighspeeddatatransmission,thedeviationexceeds±5kHz,amodecalledwidebandFM(WBFM).ImpulseNoiseAnysudden,high-amplitudevoltagepulsewillgenerateanRFfield,andradioreceiverswilloftenpickitup.•Deltatuningallowsyoutoadjustthereceiverfrequencyalone,orthetransmitterfrequencyalone,foruptoseveralkilohertzeithersideofthemainVFOfrequency.FIGURE3-8AHamScopedisplayoftheMFSKtuningmethodcalledthespectrummode.Butyoucanreversethesituationsothathigheraudiolevelscausethepulseamplitudetogodown(negativePAM).Italsovariesbecauseofanotherphenomenon:thenumberofsunspotsthatfleckthefaceofourparentstar.Jansky’santennawasasimpleaffairliketheonesusedbyhams.So,asyoucansee,nonlinearityisn’talwaysbad.Itseemslikethenaturalplaceforahobbylikethis.IfyouholdanoldNoviceClasslicense,youmustupgradeatleasttoTechbeforeyoucanusethisband.Ashortwaveorhamradioreceivershouldbesetforthenarrowestresponsebandwidthconsistentwiththemodeofreception.SometypesaresuitableforuseinAmateurRadioandshortwave-listeningstations.Someolderreceiversincorporatepreselectorsthatmustbeadjustedindependentlyofthereceivertuning.Figure1-7showsexamplesoftroposphericbendingandscattereffects.Whenthesignalpassesthroughafrequencymultiplier,thedeviationgetsmultipliedalongwiththecarrierfrequencyitself.Myownhamradiotransceiver(Fig.Therefore,theFSTVsignalgetsmodulated“negatively.”Thisconventionallowsforretracing(movingfromtheendofonelinetothebeginningofthenext)tosynchronizebetweenthetransmitterandreceiver.Thevoltage-to-currentratiounderthesecircumstancesiscalledthecharacteristicimpedanceorsurgeimpedanceofthetransmissionline.IfsomeonesaysthatyourFMsignalisfullquieting,itmeansthatyou’restrongenoughtokeepthesquelchinthereceivercompletelyopensothatyoursignalovercomesthereceiverhissofapartiallyopensquelch.Thecathode-raytube(CRT)inanoldfashionedhometelevision(TV)setneedsseveralhundredvolts,forexample.NetworksWirelesspacketnetworksaregettinglarger,easiertoaccess,andmoresophisticatedallthetime.OnCW,youcancallanotherstationonaslightlydifferentfrequencyandtheotherpartywilllikelyhearyou.TheElayercanprovidemedium-rangeradiocommunicationatcertainfrequencies.Whenyoudesignaphasingsystem(alsocalledthephasingharness)inanyantennaarray,youmustcutthebranchesofthetransmissionlinetopreciselythecorrectlengths,takingthevelocityfactorofthelineintoaccount.Anoiseblankerornoiselimitercanalsohelp,ifthereceiverhasone.Readthroughthecontentsofthewebsiteifyouholdoneofthoseolderlicenseclasses(Novice,TechnicianPlus,orAdvanced),andseehowtherulesmightaffectyou.Thelostenergyshowsupasheatinthegeneratorcomponents.ScientistsuselogarithmicscalestodepicttheEMspectrum,asshowninFig.Icouldtunethroughallofthiscoolstuffwithavariablecapacitornolargerthanagolfball.InadditiontotheHandbook,aclassicinitsfield,IrecommendallARRLpublicationsontopicsthatinterestyou!Youcanbuytheirbooksandtrainingmaterialsthroughtheirwebsiteatwww.arrl.org.TransmissionLinesAtransmissionline,alsoknownasafeedline,isamediumthroughwhichenergygetstransferredfromoneplacetoanother.15MetersThe15-meterAmateurRadiobandoccupiesthespectrumspanfrom21.000MHzto21.450MHz.It’salmostentirelyadaylight-pathband;atnighttheupperlayersoftheionosphererarelyhaveenoughdensitytoreturnsignalstothesurface,althoughexceptionsdooccur,especiallynearsunspotcyclepeaks.Whenaninductorservesinthisrole,engineerscallitafilterchoke.AnextremelylargeSWRcanalsocausesignificantsignallossinatransmissionline.Iftheyhavenone,considerstartingoneupyourself.Youcanemailmethroughthelinkatthatsiteandletmeknowwhatyou’dliketoseeinfutureeditionsofthisbook!Ifyoubelongtothehamradiofraternity,youmightfindmeon14,18,21,24,or28MHzdoingCW(Morsecode)orPSK(phase-shiftkeying).Here’sthe“moral”tothisstory:Ifyouwanttotrysomething,nomatterhowhighthetheoreticaloddsagainstyouseemtobe,goahead.PowerGainExpressionsSupposethatyousymbolizetheERP,inwatts,foragivenantennaasPERP,andtheappliedpower,alsoinwatts,asP.Whenyouplacethefeedpointatleast1/4wavelengthabovetheearth,youneedonlythreeorfourradialstoobtainlowlossresistanceforhighefficiency.HaveYouHeard?ThefirstIFchainfollowsthefirstmixerandprecedesthesecondmixer,andthesecondIFchainfollowsthesecondmixerandprecedesthedetector.AhamFAXtransmissionrequiresafewminutestosend.Someofthemostsignificantinnovationsincommunicationshistoryhavearisenfromtheactivitiesofradioamateurs“justhavingfun.”SingleSidebandByfarthemostpopularHFmode,singlesideband(SSB,alsocalled“phone,”athrowbacktothedayswhenvoicecommunicationswascalled“radiotelephone”)evolvedfromtheolder,lessefficientAMtechnology.Powergainfigurestakenwithrespecttoadipole(initsfavoreddirections)areexpressedinunitscalleddBd.Someengineersmakepower-gainmeasurementsrelativetoaspecializedsystemknownasanisotropicantenna,whichtheoreticallyradiatesandreceivesequallywellinalldirectionsinthreedimensions,soithasnofavoreddirection.Thisbandliesinasortof“transitionzone”asyougoupinfrequency,wherethepropagationbeginstogetbetterinthedaytimethanatnight.Waitanotherhalfminuteorso,andifnobodytellsyouthatthefrequencyisinuse,youcangoaheadandsendyourCQ.Overmodulationcausesaphenomenonknownassplatter,which,ifnotfilteredoutsomewhereintheIForRFchainofthetransmitter,greatlyincreasestheemittedsignalbandwidthandcancauseinterferencetostationsonnearbyfrequencies.InSSBorothervoicemodes,speakclearlyatamoderatepaceusingphoneticswhennecessary.Thereceiverevaluateseachtransmitteddatabitforablockoftimelastingforthespecifieddurationofasinglebit.Thisstateofaffairscanhaveanadverseeffectonthebehaviorofatransmitterorreceiverconnectedtotheantennasystem.Myhamstationcomputerhasbothoftheseprogramsinstalled.I’veheardthesesignalsat5,10,and15MHzquiteregularly.Mostgeneral-coveragereceiversfunctionatallfrequenciesfrom1.5MHzthrough30MHz.Somealsooperateinthestandardbroadcastbandat535kHzto1.605MHz.Afewreceivers,calledallwavereceivers,canfunctionbelow535kHzandintothelongwaveradioband,aswellasinbandsatfrequenciesabove30MHz.Anyonecanbuildorobtainashortwaveorgeneral-coveragereceiverandlistentosignalsfromallaroundtheworld.AtB,anamplitude-versus-timegraphofanSSBsignalwiththesamesine-waveinputbutsufferingfrompeakclipping,whichcanproducesplatter.Thisdeviceconsistsofacoilwoundonasolenoidal(rod-shaped),powdered-ironcore.Youcanadjusttheanti-VOXsensitivitysothatitwillkeepyourVOXcircuitfrom“chasingitsowntail,”andyetstillallowyoutotransmitbyspeakingintothemicrophone.Alightportablestationalmostalwaystakestheformofahandheldtransceiver.MaximumUsableLowFrequencyForanytwopointsseparatedbymorethanafewkilometers,radiocommunicationworkswellonlyatcertainfrequencies.Extrapoweramplificationshouldnotbeusedwhenit’snotnecessary.Thisprocessmakesitpossibletouseareceivingfilterhavingextremelynarrowbandwidth.Ifyou’reaNovice,Tech,orTechPlusoperator,you’llhavetoupgradeatleasttoGeneralbeforeyoucanfireupyourtransmitterhere,exceptintoadummyload.120MetersRadio-wavepropagationat2.300MHzresemblesthatattheupperendofthestandardAMbroadcastband.Aswith75meters,worldwidecommunicationsandreceptiontakeplaceatnight.Leavelotsofopeningsforsuchfolks!Onarepeater,youshouldwaitafewsecondsaftertheotherstationfinishesatransmission,andthenstartyours.Inanycase,youhadbetterprepareyourselfforalearningcurvewhenyoustartworkingwithcommunicationprogramslikethese.FIGURE2-2Infreespace,wavelengthvariesinverselywithfrequency.MyexuberanceknewnoboundswhenImademyfirstcontacton7.185MHzwitharadiohaminZeeland,Michigan,usingMorsecodethatIpoundedoutwithasimpletelegraphkey.TheCitizensRadioServicehasbeen“spicedup”byso-calledpiratesandfreebanders,whouseillegalamplifiersand/oroperateoutsidethelegalfrequencylimitsoftheband.Thistypeofparallel-wirelinecanofferperformancecomparabletoladderlinewhenproperlyinstalledandmaintained.Thelowercase,italicGreeklambda(l)means“wavelength.”Thegain,f/bratio,andf/sratiosofanoptimizedYagiallincreaseasyouaddelementstothearray.Some,butnotall,receivingantennascantransmitsignalswithreasonableefficiency.ThisfeatureispopularinDXing.Theoutputsofthereceiverdetectorsgointoasingleaudioamplifier,asshowninFig.Theconductorsarestrandedcopper,usuallyofsizeAWGNo.14toNo.20.Thenotionofportableradiooperationbringstomindthe“walkie-talkies”usedbysecuritypersonneloryoungchildren.Inthewintertime,atnight,orduringsunspotminima,youwilloftenfindthatcontactsarepossibleonlyuptodistancesof30to40kilometersonthisband.Let’stakeacloselookatthemostcommonformsthathamradiocommunicationtakes.Thiscapabilitycanproveinvaluablewhenyoudrivethroughplaceswhereneithercellphonenorrepeatercoverageexists.MostnotablearethefrequenciesbelowthestandardAMbroadcastband,whoselowerboundaryliesat535kHz.AcoupleofsmallLFbandshavebeenproposedrecently,andradiohamswillprobablygainprivileges“downthere”beforetoolong.TipWhenproperlydesigned,asinglehelicalantennacanprovideabout15dBdforwardgain.Table1-2showstheInternationalMorseCodecharactersusedintheUnitedStatesandothercountriesthathavethesamealphabetastheEnglishlanguagedoes.Only60wattsofoutputandaquarter-waveantenna,comprisingachopped-offCBwhip,didthejobsowellthatIremembered,onceagain,whyhamscall10metersthe“magicband”!Aftertakingadvantageoftheabove-mentionedguidelinesasastartingpoint,youshouldlistenonalltheHFbands,whetherit’swinterorsummerordayornight,andfindtheonewiththemostevidenceofDXactivity.On15meters,complexdirectionalantennasbecomemechanicallymanageableevenforthehamwithoutcivilengineeringexperience,providinggain(extratransmittedpower)infavoreddirectionsandattenuation(suppression)ofreceivedsignalsfromunwanteddirections.ThisfieldinducesACinanynearbyobjectthatconductselectricity,suchasyourradioantenna.PhasemodulationisemployedinmanymoderncommunicationsradiosbecauseitlendsitselftothefrequencysynthesizersthathavereplacedtunedLCvariable-frequencyoscillators.It’sgreatforDX,too!Hamsdon’thavetoshare17metersastheydowith30meters,andfulllegalpowerisallowed.Notonlywilltheseprecautionsminimizephysicaldangertoyourpersonandproperty,butalsoitwillensurethatyour“antennaranch”doesn’teffectivelyvoidyourhomeowner’sinsurancepolicy!Warning!CHAPTER8HamOperatingBasicsIfyou’rereadingthischapter,Iassumethatyouhaveahamlicense,perhapsanewone.6-1),whichcovers160metersthrough70centimetersandcanworkinallpopularmodes.FIGURE1-7Theearth’sloweratmosphere(thetroposphere)canaffectradiowavesatsomefrequencies.Ithasnothingtodowithparasiticoscillation,aphenomenonthatcantakeplaceinmalfunctioningRFpoweramplifiers.Inprefabricatedladderlines,thewiresareusuallyseparatedbyacentimeterortwo,andconsistofAWGNo.16orNo.18soft-drawnuninsulatedcopperwire.Ideally,youshould“tweak”yoursuppressedcarrierfrequencysothatitlies1.500kHzbelowthechannelcenter.Ifyoumustuseanextensioncord,gotoagoodhardwarestoreandgetonewiththelargestpossiblediameterconductors,ratedtocarrycurrentthatequalsorexceedsthebreakerrating.Forthisreason,somepeoplecallLFradiosignalskilometricwaves.TipYoucanincreasetheworkablebandwidthofaninductivelyloadedmobileantennabyplacingatransmatchatthetransceiver’santennaconnection,betweentheradioandthefeedline.Ingeneral,asthewavelengthgetslonger,efficienttransmittingantennasgrowlargerincommercialapplications.Ifovermodulationoccurs,peakclipping(Fig.NoticethatwhilehamradiooperatorsenjoyoperatingprivilegesinnumerousbandsthatcoveranexcellentoverallsamplingoftheHFspectrum,theAmateurRadio“slices,”intermsofsheerquantity,adduptoonlyasmallpartofthe“wholepie.”FIGURE4-1Thehamradiobandsbelow30MHzasof2013,onalinearscaleaccordingtofrequency.Thedotcomprisesamarkconditionthatlastsforonebit;thedashisamarkthatlastsforthreebits.Thefrequencyoffset,ordifferencebetweentheLOandsignalfrequencies,determinestheaudiooutputfrequencies.Troposphericscatteringandbendingoftenallowforcontactsovergreaterdistances,sometimesseveralhundredkilometers.SharingwithOtherServicesHamsmustsharethe60-meterbandwithotherservices,takingpainstoavoidinterferingwiththoseservices.Coronaecanoccurinsideacoaxialcablethatfeedsanantennajustbeforethedielectricmaterialbreaksdown,ruiningthecableforgood.Adipoleantennafedwithabalancedopen-wirelinedoesn’tneedadedicatedRFground,nordoesaYagiorotherwell-designedantennafedwithcoaxialcable.UsuallytheyappearonthesignalsfromDXstationsincountrieswhosepeoplelackgoodaccesstomoderntechnologies.You’dalsoreducethesignalbandwidthtojustabouthalfthebandwidthofanAMsignalmodulatedwiththesamevoice(actually,alittlelesswiththecarrierandonesidebandcompletelygone).Hoboken,NJ:WileyPublishing,2013.EachverticaltracerepresentsanEMsignalataspecificfrequency.FIGURE2-11BasicgeometricalschemefortheDigiPandisplay.Youmustconnectthetwoantennastogethersothenoisesignalscanceleachotherout.Butkeepinmindthefactthat,inmostcontests,you’llgetmorepointsontheaverageifyoumakethemonasmanydifferentbandsaspossible,andnotallononeortwobands.TheMUFalsovarieswiththetimeofday,theseasonoftheyear,andthesunspotactivity.Mosttransceiverswillshowyou,onthefront-paneldisplay,whenthathappens.Athighfrequencies,skipoccursoften,especiallyabove5MHzorso.Wilesmakeupforweakness.Thenyouconnecttheotherendofthefeedlinetoaradiotransmitter.Ifsomeonetellsyouyou’re“20over9”(extremelyloudsignal)whileyou’rerunning1500wattsoutputinacasualcontact,youmightaswellpoweryourlineardownandrun“barefoot.”LinearshavealwaysbeenpopularamongDXersandcontesters.•Harmonicsuppressionisthedegreetowhichharmonicenergyisattenuated,withrespecttothefundamentalfrequency,intheoutputofaradiotransmitter.Gradually,theFederalCommunicationsCommission(FCC)easedthecopyingstandardsforUnitedStateshamradiooperators,andultimatelytheyabolishedthecoderequirementforallclassesoflicense.5-6B).Onaspringorsummerafternoonwhensolaractivityishighbutnotstormy,the20-meterbandcanprovideholdersofGeneral,Advanced,andExtraClasslicensesagooddealoffun,includingplentyofDX(longdistancetoforeigncountries).You’llwanttoknowhowyousound,orwhetheryou’recausingsplatterorotherwiseemittingasignalthat’snotstate-of-the-art.Thefront-endamplifiermustbeaslinearaspossible,andshouldbecapableofhandlingverystrongaswellasveryweaksignals.Totuneasignalin,youadjustthepositionsofthedashedlinessothattheycoincideascloselyaspossiblewiththe“edges”or“skirts”ofthesignal.Thatphenomenonsometimespresentsaprobleminradiotransmittingapplications.Inlatter-dayradios,thisprocessmayinvolvenothingmorethanhittinga“tune”buttonforacoupleofseconds.Worldwidecommunicationandreceptiontakeplaceoverpathsthatlieentirelyonthedaylighthalfoftheearthnearlyeverydayofeveryyear.•Towerandantennaclimbingconstitutesajobforprofessionalsonly.InthecasesofVenusandMars,duststormsandvolcaniceruptionswouldlikelybethecauseofsferics.TodayTechscanusethesameCWbandsegmentsasNovicescan,inadditiontoRTTY,data,imaging,messageforwarding,andothermoreexoticmodesontheVHF,UHF,SHF,andmicrowavebands.Butonceyouhavethatpieceofpaper,youcangetinvolvedwithalltheknown(andasyetunknown)communicationsmodes.IfyouhaveasubstantialradiobutcanscaleitdowntoafewwattswithanRFoutputcontrol,QRPofferstheadvantageof“no-worry”continuouscarrieroutputforthenon-CWdigitalmodes,suchasPSK31,RTTY,orMFSK.NotaTweakFreak?Insertthephoneplugintothemicrophoneinputofyourcomputer.YoucantransmitSSTVimagesandvoicetransmissionsatthesametimebysendingthepicturesononesidebandandyourvoiceontheothersideband.CallingaStationImaginethatyouhearastationcallingCQorendingacontact,andyouwanttostartaQSO.Sandstorms,duststorms,andvolcaniceruptionsalsoproducesomelightning,contributingtotheoverallsfericslevel.TechTidbitSomeerrorcorrectionmethodsemployhandshaking,inwhichthereceivingstationsendsbitsequencescalledpacketsatfrequentintervalsbacktothetransmittingstationsothetransmittingstationcancheckforaccuracyandrepeatapacketifit’swrong.Weatherfrontscanenhancethebendingeffectandalsoallowforoccasionalcontactsasaresultofducting,inwhichradiowavesgettrappedwithinalayerofcoldairsandwichedbetweentwolayersofwarmerair.Then,onceyouhavemetallthoserequirements,youmustmakesurethatthegroundslotinyouroutletactuallygoestothehouseholdground.Ifyou’vebeenahamradiooperatorformorethanacoupleofyears,you’vedoubtlesswitnessedeventsofthissort.Forvoicecommunications,themaximumbandwidthforNBFMisabout6kHz,or3kHzaboveandbelowthecarrier.Someaudionotchfiltersworkautomatically;whenaninterferingaudiotoneappears,thenotchfindsandmutesitwithinafewtenthsofasecond.Thecordontherightgoestomyhamshack,severalLEDlightsforthehouse,andallmycomputersbywayofapowerstripinthegaragewithanLEDlamptoindicatewhenit’sgettinggeneratorpower.HeadsUp!Transmissionlineshavelowervelocityfactorsthansingleconductorsdo.Thislayerabsorbsradiowavesatsomefrequencies,effectivelypreventinglong-distanceradio-wavepropagation.7-2A.TheMUFdependsonthelocationsandseparationdistanceofthetransmitterandreceiver.Atnight,orduringsolarminima,thisbandcango“dead”forweeksormonthsatatime,exceptforlocalcommunicationsuptoafewkilometers.TipIfyouplantobuildanddesignarepeater,contacttheAmericanRadioRelayLeague(ARRL)foradviceanddirection.Thedesiredsignals,however,remainedasstrongasever.AsImentionedafewmomentsago,gettingahamradiolicenseoncerequiredknowledgeof,andproficiencyin,theMorsecode.AtA,thedipole.AmateurFAXtransmissionshaveresolutioncomparabletothatofanycommercialtransmission.ForTechiesOnlyInanyFMorPMtransmission,thedeviationinthefinaloutputshouldequalorexceedthehighestmodulatingaudiofrequencyifyouwanttogetoptimumperformance.Youextendtheradialsstraightoutfromthefeedpointatananglebetween0°(horizontal)and45ºbelowthehorizon.SendingCQIfyouwanttostartacontactbutdon’thearanybodyelsesendingCQorendingacontact,youcansendyourownCQafteraskingifthefrequencyisinuse.Soifyouhearsomeonehavingacontactonaparticularchannel,don’ttransmitthere.Backfeedcanendangerutilityworkersanddamageelectricalsystemcomponents.Ifyousendoutaconstant,unmodulated,purecarrier,thePEPequalstheaveragepower.Thetopoftherangeiscalledthemaximumusablefrequency(MUF).ForTechiesOnlyThemaximumcommunicationsrangethatyoucanexpectwithmeteorscatterpropagationdependsonthealtitudeoftheionizedtrail,andalsoontherelativepositionsofthetrail,thetransmittingstation,andthereceivingstation.Youcaneliminate,oratleastminimize,therippleintherectifieroutputusingapower-supplyfilter.AnOldTimer’sOpinionIrecommendthatyougetaQRO-capableradioforyourmobileapplications.Ward,HamRadioforDummies,2nded.Thepresenceofplasticspacers,employedtokeeptheconductorsevenlyseparated,willlowerthisvalueslightly.Hamradiooperatorshaveasmallfrequencyallocationnearthisband.Ifthepileupgrowsextreme,somerudenesswillemerge,andyou’llhearpeoplesendingtheircallsignsrepeatedlyandcontinuously.InFSTVbroadcasting,theimageisgenerallysentasanAMsignal,andthesoundgoesoutasanFMsignal.Adiscriminatorwillrespondtoamplitudevariations,butyoucanuseanamplitudelimitingcircuittoovercomethiseffectifitposesaproblem.You’veobtainedalltheinterconnectingcablesthatyou’llneed,andyou’rereadytoputitalltogetherandgetontheair.Thesignalantennawasa16-foot,ground-mountedverticalantennafedwithcoaxialcable,intendedmainlyforoperationonthe14-MHzhamradioband.Tosupportthatantenna,IusedaCometmagmountepoxy-gluedtoapieceofwood,whichIthenC-clampedtothelipofthetruckbed(Fig.FormostFMandPMvoicetransmitters,thedeviationisstandardizedat±5kHz,amodecallednarrowbandFM(NBFM).Moreexoticmodesofcommunication,suchasauroralpropagationandmeteorscatter,occasionallymanifestthemselveshere.AgoodtutorialforthispurposeisBeginner’sGuidetoReadingSchematics,3rdedition(McGraw-Hill,2013).Butatmanyfrequencies,cosmicnoisearrivesatthesurfaceatfullstrength.Whenyouorienttheloopjustright,sothatthenullpointsinthedirectionofanoffendingsignalornoisesource,theunwantedenergywillgowaydowninstrength.InsteadofconnectingthecomputertothecommercialInternetbymeansofacable,wireless,orsatellitemodem,youinterfacethecomputerwithahamradiotransceiverusingaterminalnodecontroller(TNC),whichactsasaspecialpurposemodemwithbuilt-inmemory.Figure1-4showsahamradiotransceiverforuseinavehicle(upperunit)onthe2-meterbandcorrespondingtofrequenciesof144to148MHz.Twowayradiousefromanysortofvehicle(car,truck,boat,train,aircraft,orevenbicycle)iscalledmobileoperation,andradiosespeciallydesignedforthatapplicationareknownas(youguessedit)mobileradios.Andincaseyou’vewondered,switchingoffthemainbreakeratyourutilityboxwillnotguaranteethatnostrayvoltagecanmakeitswayontothepowerlinesoutsideyourhouse.NotethegroundwiregoingfromthebaseoftheATAStoascrewinthetruckbed.Here’showIsendaCQundermostconditions:CQCQCQDEW1GVCQCQCQDEW1GVCQCQCQDEW1GVW1GVW1GVKAvoidsendinglongCQs.Ifyoudothat,QSOcandidateswillgetboredandtuneoffyourfrequencyafterawhile.•Intermodulationspurious-responseattenuationisexpressedindecibels.AllocationsbyLicenseClassIfyouhaveaGeneral,Advanced,orExtraClasslicense,youcanoperateonanyfrequencyintheband.RadiosgetgenerallylesspowerfulatUHFandmicrowavefrequencies,though.Thiseffect,calledsporadic-Epropagation,happensquitealotovertransequatorialpaths(pathsthatcrosstheearth’sequator)afewweekseithersideoftheequinoxes,whenthesunliesinthesameplaneastheearth’sequator.AnEMPcanbegeneratedbyarcing,andonaradioreceiver,multiplesmallEMPssoundlikepoppingorstaticbursts.Forexample,ifsomeonesaysthatyourmobileFMsignalhasalternatorwhine,itmeansthatyourvehicle’salternatoriscausingtroublewithyourtransmitter(modulatingyoursignalwithanaudibletonethatvariesinpitchasyouralternatorspeedsupandslowsdown).Whileyoumightimpresspeoplebyzippingalongat35or40WPM,suchshow-offishnesswillspooklessexperiencedoperators,evenifyoursignalisstrongenoughthatitwouldmakeforeasycopyotherwise.Intheoldendaysofradio(andsometimesstilltoday),engineersobtainedFMbyapplyinganaudiosignaltoavaractordiodeinavoltage-controlledoscillator(VCO).Intheextremecasesofashortcircuit,opencircuit,pureinductance,orpurecapacitanceattheloadendoftheline,theSWRistheoreticallyinfinite.Thedeadspotphenomenonismostnoticeableatthehighestfrequencies.AloopstickdisplaysdirectionalcharacteristicssimilartothoseofthesmallloopantennashowninFig.(Youmusthaveahamradiolicensetoconductexperimentsthatinvolvetransmittingon136kHz.)ForLowFERoperation,youcan’tuseatransmittingantennawithanoveralllengththatexceeds15.24meters,includingthetransmissionlinebetweentheradioandtheradiatingelementitself.Youcanprogramtheradiotoconstantlysweepthroughagivenspanoffrequencies(thelimitsforwhichyoucanprogramintotheradio’smicrocomputer)untilitencountersanoccupiedchannel.AdvancedClasshamsgettooperateonafewmorefrequenciesthanGeneralsdo,butAdvancedoperatorsdon’tgeteverything.Theelevationplane(orE-plane)patterndependsontheheightoftheantennaaboveeffectivegroundattheviewingangle.DiscontinuedLicenseClassesOnceinawhileyou’llencounterahamwhoclaimstoholdalicenseofsomeclassotherthanthethreedescribedabove.It’smadeoftelescopingsectionsofaluminumtubing,mountedonadeckrailing,andcangouporcomedowninacoupleofminutestoaccommodatetherapidlychangingweatherconditionscharacteristicofmylocation.SharingwithOtherServicesHamradiooperatorssharetheupperhalfofthisband(1.900MHzto2.000MHz)withradiolocationservices.Figure2-4showsthelocationsoftheshortwavebroadcastbandsaccordingtofrequency.TheRFenergybetween−3kHzandthecarrierfrequencyiscalledthelowersideband(LSB);theRFenergyfromthecarrierfrequencyto+3kHziscalledtheuppersideband(USB).ForCW,itvariesalittlebit,dependingonyoursendingquirks,butusuallytheaveragepowerisabout40to50percentofthePEP.SomeAmateurRadiopoweramplifiersusevacuumtubes,eventoday,whichneedupwardsof1000volts!Thetransformersintheselinearsarestep-uptypes.Thesefiguresrepresentelectricaldimensions(takingthevelocityfactorofwireortubingintoaccount),notfree-spacedimensions.High-gaindirectionalantennasmustremainconstantlyaimedatthemoon,arequirementthatdictatestheuseofsteerableantennaarrays,preferablycontrolledbycomputers.Onceyoudothatcalculationafewtimes,you’llrealizehowslowlyhamradioCWconversationsactuallygo,relativelyspeaking.BothofthemoriginatedforMicrosoftWindowsXP,butIhaverunthemonWindows7andWindows8.Youtunethereceiverwithinthepassbandbygivingyourmouseasingleleftclickatthetopofthebrightcoloredlinerepresentingthesignalyouwanttodecode.Ahalf-wavedipolemeasuresonlyabout7metersfromendtoend,andafull-size,quarter-waveverticalrisesonlyabout3.5metersupfromthefeedpoint.Somepeoplemakeahobbyoutofcollectingandrefurbishingold-timeshortwaveradios.Let’slookathowthesebandsbehave,soyou’llhaveanideaofwhattoexpectwhenyoutuneyourradiotothem.Areyouinvolvedinanemergencywhereyouroperationwilltakeplaceonapredeterminedfrequencyorfrequencies?Ifyoutakeitas5dB,thenyoucanseethatIgota30-dBimprovementwiththenoise-cancelingantennasystem,whichmeansthatthenoisepoweratmyreceiver’s“antennaterminals”(T-4Xmicrophonejack)wentdowntoonly1/1000ofitspreviouslevel.Quarter-WaveVerticalsThephysicalspanofaquarterwavelengthantennaisrelatedtofrequencyaccordingtotheformulaLm=75.0v/fowhereLmrepresentsaquarterwavelengthinmeters,forepresentsthefrequencyinmegahertz,andvrepresentsthevelocityfactor.Speechcompression,alsocalledamplifiedautomaticlevelcontrol(AALC),isusuallycarriedoutinthemicrophone-amplifiercircuitsofatransmitter.Figure7-11BshowsanalternativeschemeknownastheCassegraindishfeed.Ingeneral,asthefrequencygoesup,sfericspropagateforshorterandshorterdistancesbeforetheyfadedownenoughtogiveyouabreak!Sodon’tletthefactthatit’sasummerdayintheAmericanMidwestdeteryoufromlisteningonthisband.Intheory,there’snolimittohowlargetheSWRonatransmissionlinecanget.AnOldTimerRejoicesWhenIgotthevanitycallsignofmychoice,W1GV,in1977,IpickedacharactersequencethatIknewotherhamswouldeasilycopyonCW.Thedwelltimeequalsthelengthoftimethatthesignalremainsonanygivenfrequency;it’sthesameasthetimeintervalatwhichfrequencychangesoccur.ItprobablyhadacircuitconfigurationsimilartotheoneshowninFig.60MetersThebandknownas60metersdoesnotcompriseacontinuousspanoffrequenciesastheotherhambandsdo;instead,ithaswell-definedchannels,eachone3.000kHzwideandcenteredatthefollowingfrequenciesasofthiswriting:•5.3320MHz•5.3480MHz•5.3585MHz•5.3730MHz•5.4050MHzYoursignalcan’tlegallyexceed2.800kHzinbandwidth,andyoumustcenteryoursignaltocoincidepreciselywiththechannelcenter.VOXorPTT?That’salittleboxaboutthesizeofanold-fashionedoutboardelectronickeyer.Also,ifyouplacethelinenearobjectswithahigherdielectricconstantthanair,thecharacteristicimpedancewillgodownalittle.InagoodRFgroundsystem,eachdevicegoestoacommongroundbus,whichinturnrunstotheearththroughasingleconductor.ThisgainiscalculatedanddefinedindBd.Ingeneral,asthewavelengthdecreases(thefrequencygetshigher),you’llfinditeasiertoobtainhighforwardgainfigures.Theprospectofgettingonthisbandhasmotivatedalotofpeopletoupgrade!Table4-4breaksdownthe20-meterbandaccordingtolicenseclasssuballocationsandmodeusagerestrictions.Thesensitivityismaximumoffthesidesofthecoil(intheplaneperpendiculartothecoilaxis),andasharpnulloccursofftheends(alongthecoilaxis).Ifyoucanaddmobilecapability,somuchthebetter;ifyoucanaddHFcoverage,you’vegotthebest.StayTuned!Fordecades,hamradiooperatorshavelongedtoregainsomeoftheprivilegestheyhadintheearliestdaysofwirelesscommunicationsmorethan100yearsago.Otherwise,hamscanuseallknownmodesthroughoutallbands,excepttheycan’tlegallyusefast-scantelevision(FSTV)on1.25meters.Let’stakealookatthehamradiobands,learnhowtheyworkontheair,andoutlinethemodeandpowerrestrictionsimposedbytheFCC.Theworsetheconditionsgrow,themorethesetsofcharactershavetoberepeated,andtheslower,inpractice,thecommunicationsget.Thefeed-pointvalueofRRoverperfectlyconductinggroundisapproximately37ohms,halftheradiationresistanceofacenter-fedhalf-waveopendipoleinfreespace.Thesolarfluxvarieswithfrequency.TheSWRfigurecanserveasanindicatoroftheoverallperformanceofanantennasystembecauseahighSWRindicatesaseveremismatchbetweentheantennaandthetransmissionline.22MetersThoseofyoufamiliarwiththe20-meterhambandat14.000MHzto14.300MHzwillknowwhatconditionstoexpectontheshortwavebroadcastbandat13.570MHzto13.870MHz.And,foryouSWLloverswhohavethoughtaboutgettingahamradiolicensebutkeepputtingitoff,thisbandoughttogiveyouagoodfeelingforwhatyoucanexpectwhenyoufinallydogetontheairandoperateon20meters,themostpopularofthehambands!Worldwidereceptionoccursonthedaylightsideoftheplanetalmostallthetime,andwhenthesunspotcyclereachesitspeak,goodreceptionandcommunicationcanbehadatnight,aswell.Asthefrequencyincreasesstillmore,asyou’velearned,thecircuitwillfailagainattheshortwaveMUF.StaySafe!Inclosingthischapter,pleaseletmereiterateamandate:Alwaysplaceyourpersonalsafety,andthesafetyofthosearoundyou,aboveyourdesiretohave“coolfun”withyourradio.It’smostcommoninandneartheArcticandAntarctic.That’swhyradiohamslookforwardeagerlytoperiodsofhighsolaractivity.Seriousinterferencecanoccurinshortwavereceivers,butitgetslesssevereasthefrequencyrises,anditrarelyposesaproblemabove30MHz.Youcanminimizeimpulsenoiseproblemsbyensuringthatyouhaveagoodgroundsystem.InAMbroadcastingwheremusicgoesalongwithvoices,theaudioinputenergygetsspreadoverawiderbandwidth,nominally10kHzto20kHz.Theincreasedbandwidthprovidesforbetterfidelity(soundquality)sothatmusicdoesn’tsoundmuffledinthereceiver.Beforeabout1970,youcouldoftenhear850-Hzshiftsignalsaswell,butthatmodehasfallenfromfavorbecauseittakesupmorebandwidththanaham-radioRTTYsignalneeds.Conversely,becauseautumnandwinterhavedayswithmoredarktimethansunlittime,thebandsat10MHzandbelowwillusuallyworkbetterforDXduringthosemonths.Inarepeater,thetransmittersignalmustdifferinfrequencyfromthereceivedsignalbyatleastacertainamount,calledtheoffsetorsplit,whichvariesdependingontheband.6-7.5.Polarizationcanalsohavea“slant”thatgoesatanyangleyoucanimagine.DoyouwonderhowthereceiverinanAMTORcontact“knows”whetherornotanerrorhasoccurred?Sometimes,atinyloopstickcan“hear”adistantsignalevenwhenalargeoutdoorantennacan’t!LargeLoopAlargeloopantennahasacircumferenceofahalfwavelengthorafullwavelength(dependingonthedesign),formsacircle,hexagon,orsquareinspace,andliesentirelyinasingleplane.TipWhensendingsignalreportsonCW,anoperatorwilloftentruncateanumber9toaletterN.AdvantagesofHFPortableForsomehams(myselfincluded),nothingsurpassesthethrillofworkingDXwithaportablestationontheHFbands.TipMostsmallgeneratorenginesburngasoline.Aroundastraightwire,theelectricorEfluxlinesrunparalleltothewire,andthemagneticorMfluxlinesencirclethewire,asshowninFig.Soanyeffortsto“cleanup”electricity,inthehopesofgettingridofitspotentialilleffects,arefutile,unlessweasasocietydecidethatwedon’twanttolivewithutilityprovidedelectricityanymore!TryThisCircuitforRelief!Youmightbeabletoreducethenoisefromdirtyelectricityatfrequenciesbelowabout100kHzbyusingtwoantennasthatreceivethenoiseatequalamplitudesbutreceivethedesiredsignalsatdifferentamplitudes.ThebandwidthofaFAXsignalisthesameasthatofanSSBsignal.Theyhavealsoprovenvaluableintraffichandling,especiallywhenthetraffichasapriorityoremergencynature,andyouwanttoensurethatyourmessagesreachtheirdestinationsintheshortesttimepossible,withouthavingtorepeatyourselfbecauseofinterferenceormarginalbandconditions.•SINADisanacronymbasedonthetechnicalexpression“signaltonoiseanddistortion.”TheSINADfigureisfrequentlyusedtodefinethesensitivityofanFMreceiveratVHFandUHF.5-11and5-12,createadangerbyoverloadingthewalloutletanditsassociatedhousewiring?TheyhangoutincertainpartsoftheHFbands,mostlyintheupperpartsofthedigital-modesegments,just“above”(infrequency)theMorsecodegang.Hoboken,NJ:WileyPublishing,2009.Thatmeansit“hears”on146.34MHzand“speaks”on146.94MHz.Inthatcase,you’llsetyourradiototransmiton146.34MHzandreceiveon146.94MHz.Hamscallthatfrequencycombination“34/94.”Becauseyoutransmitonafrequencybelowtheoneonwhichyoureceive,hamscallthatsplit“negative”(specifically,−600kHz).Theresultingantenna,calledaJpole,radiatesequallywellinallhorizontaldirections.TABLE8-3SomeVoice-ModeExpressionsinHamRadioJargonEndingaQSOInSSB,endingacontactworkslikeendingaface-to-faceortelephoneconversation,withtheexceptionofthestationidentificationrequirements.Tothem,humanmadenoiseandinterference(includinglegitimatebroadcastandcommunicationssignals)constitutesamajornuisance,justasitdoeswithhamandshortwaveradioenthusiasts!Here’saTale!In1965,ArnoPenziasandRobertWilsonoftheBellLaboratoriesobservedcosmicnoisethatseemedtocomefromeverywhere,fromalldirectionsatonce.It’sabigband,extendingfrom28.000MHzto29.700MHz.AmateurRadiooperatorsenjoyunrestricteduseoftheband;itinvolvesnosharingwithotherservices.Here’saNotion!Agiantloop,measuringseveralwavelengthsincircumference,canbeinstalledhorizontallyamongmultiplesupports,suchascommunicationstowers,trees,orwoodenpoles.Anoldcomputer,defunctformostotherapplications,willusuallyworkfineforRTTY,PSK,MFSK,andotheremergingdigitalmodes.Ontheaverage,thesolarfluxriseshighestnearthepeakofthesunspotcycle,anddipslowestnearsunspotminima.Oursunhasamagneticfieldthatoscillateswitha22-yearcycle.Figure2-8showsthebasicconfiguration.Whileyoucan,intheory,inductivelyloadashortenedquarterwaveantennatotakepoweronanyfrequency,youcan’texpectittoworkinalightportablesituationbecausesuchanantennaneedsasubstantialRFground,andaneffective“walk-aroundground”hasn’tbeeninventedyet!Nevertheless,thehamradiospectrumat6metersandshorterwavelengthsoffersspecificadvantagesforanytypeofportableoperation.FirstFloorThefirstflooroffersseveraladvantagesforfixedhamradiostations.Inthatcaseyouhavecircularpolarizationifthefieldintensitiesremainconstantallthewayaroundthewholerotationalcycle.Productdetectionoccursatasinglefrequency,ratherthanatavariablefrequencythatischaracteristicofdirect-conversionreception.You’llgettwicethepowerforthesamenumberofamps,andyou’llgetamorestablevoltageaswell.Onceinawhileyoumighthear“DWN”or“DWN1,”butnotoften.TipIfyou’renotadventurousenoughtogotoaforeigncountryandoperatefromthere,youcanalwaysvisitARRLHeadquartersinNewington,Connecticut,andarrangetooperatetheirofficialstation,W1AW,foranhourortwo.Theseconstraintskeepchanging,soforthelatestinformation,IrecommendthatyouvisittheARRLwebsiteatwww.arrl.orgTheFCCrulesalsostatethatyoumustusethelowestamountofoutputpowernecessarytocarryonthecommunicationsthatyouwanttodo.IfyouwanttogoonaDXpedition,youmustmakearrangementsforoperatingprivilegesinthecountryyouchoose.HerearesomegoodreasonswhyyoumightprefertochooseVHF:•MobileantennasalmostalwaysexhibitgoodefficiencyatVHFandUHF.ThePhoneticAlphabetVoice-modeoperationofferstheconvenienceofplain-languagecommunication,soit’smore“upcloseandpersonal”thandigitalmodes.However,atandnearsunspotcyclepeaks,the20-meterbandoffersworldwidecommunicationswithlowpowerandmodestantennas24hoursaday,especiallyinthesummeratlatitudesclosetothegeographicpoles.ThephotoatAshowstheprograminspectrummode,andthephotoatBshowsthewaterfallmode.Ifyouhavealow-powerormedium-powertransmitter(150wattsoutputorless)andanotebookcomputer,you’lldookaywithacommonutilityoutletonacircuitratedat15or20amps.Ialwayskeepinmindthemaximumpowerthatthegeneratorcanprovide;Ineverletitcomecloseto“maxingout.”Youcanusethisgeneralconfigurationasatemplateforyourownsystemifyouwanttoinstallone,tailoringthespecificstomeetyourneeds.3-10B)canresult,producingsidebandelementsatfrequenciesoutsidethenormalpassband,asshowninFig.Figure5-5showsfoursimpletransmatchcircuits.Whateverbrandofgeneratoryoudecidetobuy,youshouldmakecertainthatitproducesa“clean”sinewaveforsophisticatedelectricalandelectronicdevices.Inadditiontotheradioitself,thissystemincludesacomputer,twodisplays,adigitalcommunicationsinterfacebetweentheradioandthecomputer,amicrocomputer-controlledreflectometerandRFwattmeter,anaudioamplifierforthecomputerandradio,awirelessheadset,adesklamp,andanexternalharddrivethatneedsitsown“powerbrick.”That’s10devicesorcordsintotal,allderivingtheirpowerfromasingleoutletinthewallprotectedbya15-ampbreakeratthemainutilitybox.Afullquarter-wavelengthverticalantennaat24MHzmeasures3meterstall,whilethesamesizeantenna,intermsofitswavelengthdimension,measures10meterstallat7MHzand20meterstallat3.5MHz.Whentheheightofamobileantennaexceeds3meters,itbecomesunwieldyandunsafe.Figure5-12isablockdiagramofthegeneralarrangement.Digitalmodesworksomewhatbetter,butthesignalfrequencygets“spreadout”or“smeared”overabandseveralhundredhertzwideasaresultofphasemodulationinducedbyauroralmotion.Makecertainthatyougetthelatesteditions.SplatteralsoviolatesFCCregulationsbecauseitcausesanSSBsignaltoexceeditslegallyallowedbandwidth.LoopsAnyreceivingortransmittingantennamadeupofoneormoreturnsofwireormetaltubingconstitutesaloopantenna.Tosendafaxfromahardcopy,youplaceonepage,containingtextand/orimages,intoanopticalscannerthatconvertsthehardcopyintoaseriesofbinarydigitalpulses,thatis,highandlowsignals(alsocalled1and0).Today’sall-solid-stateradiosdrawalmostnocurrentonreceive,andnotmuchontransmitifyouscaleyourpowerdowntoafewwatts.Insomecountries,however,youwillhavetogetalicensetoreceiveradiosignals(believeitornot).Whenyouconnectaloadtotheoutputofasimplegenerator,theenginehasahardertimeturningthegeneratorshaft,ascomparedwiththesituationwhennoloadexists.Inmyview,astatesideoperatorshouldplayahunter’srole,andDXshouldbetheirgame!CarryingonaQSOThelengthoftimethatyouspendinaQSOdependsontheoperatingenvironment,aswellasyourmood.Inareceiver,splattersoundslikeacracklingnoiseatfrequenciesaboveandbelowtheactualsignal.Whatwouldtheysay?Thatfewminutesgivesmetimetodeploymybackupgenerator,describedlaterinthischapter,withouthavingtoshutanyofthedevicesdown.•Actingasifyou“own”aparticularfrequency.CornerReflectorFigure7-13illustratesacornerreflectorwithahalf-wave,open-dipoledrivenelement.Althoughyoucan’texpecttogetagoodRFgroundfromthestationlocationonanupperfloor,youcanstillgetagoodRFgroundforyourwholesystemifyouputitatthefeedpointfor,say,aground-mounted,verticalantenna.LookingforDXTheclassicsignatureofaDXstation’spresenceisaso-calledpileupofstateside(UnitedStates)stationscalling,usuallysendingtheirowncallsignonceortwice,andnothingelse.Figure7-12illustratestheconstructionschememostoftenused.IntheexampleofFig.You’llseethefiguregivenindecibels.•Tonenumbers(inCWonly)gofrom1to9.Ineffect,therefore,awell-equippedamateurpacketradiostationcanfunctionasacommunicationsrepeater.5-11and5-12,thepowerstripsdonotincludetransientsuppressors.Ifyou’vedonemuch“hamming”on30meters,you’llknowwhattoexpectonthe31metersandviceversa.The“MainRadio”Somehamspreferseparatetransmittersandreceivers,especiallyontheHFbands,forthe“mainradio.”However,latter-daytransceivershavegainedmanyofthefeaturesonceavailableonlywithseparateunits.ForreceptionofAMorSSBsignals,youmustadjusttheLOtopreciselythesamefrequencyasthatofthesignalcarrier,aconditioncalledzerobeatbecausethebeatfrequency,ordifferencefrequency,betweentheLOandthesignalcarrieriszero.Maybeyou’llwanttogetontheairasaLowFERandseeifyoucanmaketwo-waycontactswithotherLowFERs!Formoreinformationaboutthishobby,visitthewebsiteoftheLongwaveClubofAmerica(LWCA)atwww.lwca.orgTipIfyouwanttogetthemostoutofyourLFandVLFlisteningexperience,you’llneedareceiverwithaproductdetector,sothatitcanresolvedigitalandMorsecodesignals.Youshouldalwaysseeameterreadingof0.Informally,youcanthinkofitasextendingfromthelowestallocatedfrequencyintheUnitedStatesat9kHzuptothelow-frequencyendofthestandardAMbroadcastbandat535kHz.Thewavelengthsdecreasefrom10kilometersdownto1kilometerasyougoupinfrequencyfrom30kHzto300kHzrange.Whenthesignalfrequencyliesatthecenterofthereceiverpassband,theoutputvoltageequalszero.Arepeaterwillkeepputtingoutthecarrierforasecondortwoaftersomeonefinishesatransmission.The“windows”alsoreducetheextenttowhichrainaffectsthecharacteristicimpedanceoftheline.ThatcharacteristicmakesAMamightyinefficientwaytoconveyinformation!Figure1-9showsaspectraldisplayofagenericAMvoiceradiosignalatasingleinstantintime.•Retunethetransmitterfornormaloperatingoutputpower.LeaveCBbehaviortotheCBers,andmaintainyourhamradiopersonalitywithotherhams!CarryingonaQSOOnFM,contactsproceedliketheydoinordinaryconversation,withtheexceptionoftheidentificationrequirementsandsometechnicaljargonpeculiartoradiohams.Inaddition,duringthefallandwinter,moreofyourhemisphereliesindarknessthanisthecaseinthespringandsummer,soyoucanenjoytheadvantagesofnighttimeconditionsforagreaterportionoftheday.OnsomeweekendsIcame“backhome”toRochesterfromMinneapolisandreplacedthecoaxialcablewithalow-lossopen-wireline,oneconductorrunningthrougheachhole,andashorterandmoredirectroutetoahigherantenna.•Auto-tunefunctiongetsridoftheneedtomanuallytunethetransmitter’sfinalamplifierwhenyouchangefrequency.AllocationsbyModeOn12meters,youmustrestrictyourworktodigitalmodesonly,includingRTTY,PSK,MFSK,data,andCW,between24.890MHzand24.930MHz.Above24.930MHzandallthewayupto24.990MHz,youcanusephoneandimagingemissions.FIGURE6-3Amagneticbasemount(alsocalleda“magmount”)foraVHFmobilehamradioantenna.AtB,abidirectionalend-firearray.IfIweretoconnecttheentireloadto,say,theleft-handoutletinthesituationofFig.Inordertoensuresmoothoperationofthesystemincaseofapowerfailure,allofthedevicesgotothewalloutletthroughacommerciallymanufactureduninterruptiblepowersupply(UPS).Inmanyothercountries,therotationalspeedis3000r/min,producinganACfrequencyof50Hz.Inordertomaintainaconstantrotationalspeedforthegeneratorunderconditionsofvariableenginespeed,mechanicalregulatingdevicesarerequired.Mycarbonmonoxidedetectorsoundeditsalarmafteronlyafewminutesofgeneratorruntime!Warning!Anon-sitegeneratormustrunonlywhenyourhousewiringiscompletelyseparatedfromtheelectricutilitywiringwithadouble-pole,double-throw(DPDT)isolationswitchinstalledandtestedbyacertifiedelectrician.Youmightnoticeimprovedreceptionhere,comparedwith120meters,fromtransmittingstationsthatusemodestoutputpowerlevels.Ifyouevergetatonereportofanythingotherthan9,youhadbetterlistentoyoursignalonaseparatereceiver,andifaproblemexists,getitcorrected!AlthoughCWsignalsalmostalwayshaveperfecttonethesedays,othertechnicaltroublescanoccurinthatmode.So-calledline-of-sightpropagationcantakeplacewhenthereceivingantennaisn’tactuallyvisiblefromthetransmittingantennabecauseradiowavespenetratenonconductingopaqueobjectssuchastreesandframehouses.Eachdigipeaterinapacketradionetworkconstitutesanode.RatioDetectorforFMorPMAratiodetectorcomprisesa

discriminatorwithabuilt-inlimiter.ThereceivingantennapicksuptheenergyinamannersimilartoanRFprobeinanelectronicslab.ThiscodecomprisesalotmorecodeelementsthanBaudothas.Whichtypesofappliancesarethe“cleanest”?Inordertouseaprogramonceyou’vedownloadedit,Irecommendthatyouplayaroundwithitandseewhichbuttonproduceswhataction!(Toheckwith“help”menus!)Ihaveapersonalparadigmforlearningfreewareprogramssuchastheonesmentionedabove:COIES(“clickoneverythinginsight”).CHAPTER3HamRadioCommunicationsModesNon-hamsmightthinkthatAmateurRadiooperatorsuseonly“code”or“voice,”forgettingaboutothermethodsbywhichhamscan,andoftendo,exchangeinformation.Inductancesareinmicrohenrys(µH).Abbreviations:kHz=kilohertzorthousandsofhertz;MHz=megahertzormillionsofhertz;GHz=gigahertzorbillions(thousand-millions)ofhertz;m=meters;km=kilometersorthousandsofmeters;mm=millimetersorthousandthsofameter.RadialsandtheCounterpoiseAsurface-mountedverticalantennashouldemployasmanygroundedradialconductorsaspossible,andyoushouldmakethemaslongasyoucan.TheUPSalsohasatransientsuppressorbuilt-in.Antennaconstructionandmaintenanceshouldneverbeundertakenifyoucanseelightningorhearthunder,evenifastormappearsfaraway.Suchemissionsnotonlyannoyotheroperators,buttheycanalsogeneratedisruptiveinterference.Iftheantennaelementshavesharppointsontheends,youcanbluntthembyinstallingsmallmetalspheresonthoseends.InNBFM,thesignalbandwidthisroughlythesameasthatofanAMsignalcontainingthesamemodulatinginformation(yourvoice,forexample).Ifthereceivingstationsaysnothingorsays“notokay,”thenthetransmittingstationrepeatsthethreecharacterspreviouslysent.19MetersConditionsinthefrequencyrangefrom15.100MHzto15.800MHzresemblethoseonthe20-meterhambandandthe22-metershortwaveband.MosttransmatchcircuitsincorporateSWRmeters(reflectometers)intheirinputcircuitstofacilitateadjustment.W1GVTravelLogSurpassingalltheabove-mentionedadvantagesofHFmobileoperation,I’lladdmyownpersonalone:It’sfun!IgluedaMorsecodekeyerpaddletoapieceofwoodandsetitonthearmrestbetweenthefrontseats,asshowninFig.Thehorndesignoptimizesthef/sratiobyminimizingextraneousradiationandresponsethatoccurifadipoleisusedasthedrivenelementforthedish.Then,ifyourradioistypicalandhasanaudiopassbandof300Hzto3000HzandanRFfilterthattrimsyoursignalto2.700kHzofbandwidth,yourenergywilllieentirelywithinthechannel;infact,you’llhavealittlebitofroomtospareonthelowend.Inadirect-conversionreceiver,youcanhearsignalsoneithersideoftheLOfrequencyatthesametime,andyoucan’ttellwhichoneliesabovetheLOfrequencyandwhichoneliesbelowitunlessyouadjustthetuningdial.IfyourreceiverhasonlyanenvelopedetectorforAM,youwon’thearmuchbelowthestandardAMbroadcastbandbecauseAMtakesuptoomuchbandwidthtomakepracticalsenseatLFandVLF.Inordertousethatmode,youhavetostayabove420MHz.FulllegalpowerisallowedexceptforNovicesintheirsubbandson1.25metersand70centimeters.Thesquelchisnormallyclosed,cuttingoffallaudiooutput(especiallyreceiverhiss,whichannoyssomecommunicationsoperators)whennosignalispresent.Ithasatankthatholds1.1gallons(4liters)ofhigh-octane,unleadedgasoline.DeterminingFactorsSupposethatyouplaceathin,straight,losslessverticalwireoverflat,horizontal,perfectlyconductinggroundwithnootherobjectsinthevicinity,andfeedthewirewithRFenergyatthebottom.Theprocess,whichcausesaudiodistortionbecauseofthenonlinearityintheresponse,canusuallyyieldanintelligiblevoice,butitwillruinthequalityofmusic,andmaydisruptthereceptionofcertainkindsofdatasignals.YoucanalsolistentothepitchesofthesignalsfromoperatorscallingtheDX,andavoidsendingyourcallexactlyonanyoftheirfrequencies.Goodluck!UsingMFSK16WhenreceivingMFSK16signals,youhavetotunetheminpreciselyorelseyou’llgetnoresults.Theelectrons’velocityconstantlychangesastheyspeedupinonedirection,slowdown,reversedirection,speedupagain,andsoon.Themostcommonhamradioimagemodesaretelevisionandfacsimile(FAX).Ifyouwanttouseabattery,however,you’llwanttorunnomorethanabout100wattsofRFoutput.ThetwomostcommoncodesthathamradiooperatorsusewithFSKareBaudot(pronounced“baw-DOE”)andASCII(pronounced“ASK-ee”).•MobileHFradioscanserveasemergencycommunicationsstations,especiallyonthehighseasandinaircraft.Usecommon-sensejudgmentwhenchoosingtopicstotalkabout.Figure3-6showstheoperatingscreenforHamScopeasitreceivessomesignalsintheBPSK31mode.Inasuperhet,theincomingsignalgoesfromtheantennathroughatunable,sensitivefrontend,whichcomprisesaprecisionweak-signalamplifier.TABLE4-2SuballocationsintheUnitedStatesforthe80-and-75-meterband(3.500MHzto4.000MHz)asofMarch2012.Ifyoulocatethefilterchokeontherectifiersideofthecapacitor,thenyouhaveachoke-inputfilter(Fig.TipIdeally,acounterpoiseshouldhavearadiusofatleastaquarterwavelengthatthelowestfrequencyonwhichyouplantotransmit.Willsocietysomedaysufferamassiveutilityfailureasaresultofasolarflare?Youcancalculatetheantennaefficiency,Eff,asaratiowiththeformulaEff=RR/(RR+RL)Ifyouwanttogetapercentagefigure,theexpressionbecomesEff%=100RR/(RR+RL)Youcanobtainhighefficiencyinatransmittingantennaonlywhentheradiationresistancegreatlyexceedsthelossresistance.Alwayslocateageneratorsothatitsexhaustcanventfreelytotheoutside.HowFastIsIt?That’sthesimplestandmostcommonwaytooperateSSB.Infact,theearth-ionospherewaveguideeffectivelyshortsoutEMfieldsatfrequenciesbelowabout9kHz,andthat’swhythosefrequenciesremainlargelyignoredforuseonthisplanet.Themostspectacularlong-distanceshortwavepropagationresultsfromtheeffectsoftheuppermostlayers.FIGURE1-3Blockdiagramofawell-equippedfixed-locationAmateurRadiostation.Tothatend,thebookbreaksdownintoeightchaptersandfourappendixes.However,manymodernradioscan“hear”almostallthewaydowntotheaudiofrequency(AF)zone,whichtopsoutaround20kHz.Atypicallowerlimitforsuchreceiversis30kHz,thebottomoftheLFband,correspondingtoafree-spacewavelengthof10kilometers.IlearnedthattheCanadianstationIhadheardwiththeregenerativeradioreceiverkithadthecallsignCHU,transmittingat7.335MHz.Idiscoveredcrypticconversationstakingplaceamongindividualsinfrequencybandsaround3.5MHz,7MHz,and14MHz.IheardMorsecodeandotherunidentifiablesignalsthatsoundedasiftheycouldjustaswellhavecomefromextraterrestrialcivilizations.The“roguecurrents”usuallyoccurbecauseofelectricarcingatsomepointintheutilitygrid.Thisprecautionkeepsthepowerstripsfromsettinganything(otherthanthemselves)onfireiftheystartshortingoutandsparking,astuntthatthesethingshavebeenknowntoperform,occasionallywithdisastrousresults.Thatistosay,youcansendandreceiveMorsecodelegallyonanyamateurfrequency!However,forpracticalreasons,nearlyallCWenthusiastsstaywithinthedigitalsegmentsofbandsthataredividedupbymode;andeventhen,theypreferthelowermostfrequencieswithinthosesubbands,leavingtheupperportionstothosewhopreferRTTY,PSK,MFSK,andthelike.Itsupposedlyprovidedshortwavereception,butitdidn’tbringinmuchofanythinguntilIgottotheprojectcalledthe“RegenerativeGridLeakDetectorwithPentodeAmplifier.”ThenIheardsignalsfromallovertheworld:strangelanguages,bizarrebuzzingandswishingandwhiningnoises,andatime-standardstationthatclaimedtocomeoutofsomeobservatoryinCanada.Themaximumallowedtransmitterpowerwas5watts“inputtothefinalamplifier,”correspondingtoaround3.5wattsofactualradio-frequency(RF)outputpower.Runthemoutatvariousangles.AtB,aspectraldiagramof60-Hzenergywithsignificantcomponentsatthesecond,third,andfourthharmonicfrequencies.ReceiversforFMcanbemadeunresponsivetochangesinsignalamplitudebymeansoflimitercircuits.Inorderforacircuitofthissorttofunctionatitsbest,thesignalantennaandthenoiseantennamustliereasonablyneareachother,sotheypickuplocalhumanmadenoisewhosecharacteristicsareasnearlyidenticalaspossible.Ifyou’vestudiedabasicelectronicstextortwo,andifyou’vecarefullygoneovertheFCCregulationsaspublishedinARRLstudyguides,youshouldpassonyourfirsttry!ThenyoucanlegallytransmitwithRTTY,data,andvoicemodesonmany,butnotall,oftheAmateurRadiofrequencybands.Burlington,MA:Newnes/Elsevier,2010.Ifyoudon’thaveafavoritefrequencywithinagivenband,usethecenterfrequencyofthebandasthebasisforyourcalculation.Hamradiooperatorscommunicatebytalking,sendingMorsecode,ortypingoncomputers.Inotherwords,itmustn’tintroducedistortion.Someradiooperatorsuseselectivesquelchingtopreventunwantedtransmissionsfromcomingin.Idon’trememberthecomponentvalues.Thearcingmightoriginateinhouseholdappliances;itcantakeplaceinfaultyorobstructedutilitytransformers;itcanoccurinhigh-tensionlinesasacoronadischargeintohumidair.There’snowayaroundthatconundrum:adecentradiatingelementforLFusemustbelarge,indeed,andhighupoffthegroundtoboot.Precipitationstaticisoftenobservedinaircraftflyingthroughcloudscontainingrain,snow,orsleet.ThisandmostotherRTTYprogramsincludegraphicaltuningaidstohelpyouproperlyadjustyourradio’sfrequency.Ifyoucangetthatdipoleupatleast4meters,youcanexpectfairresults,butifyouwanttoworkDX,youshouldelevateitatleast8metersabovetheground.Forpeoplelivinginremoteareas,acombustiongeneratormightconstitutetheprimary,ifnottheonly,sourceofACelectricityforcommonappliances.Ifascreenormeshisused,thespacingbetweenthewiresmustbeasmallfractionofawavelength.AlthoughamateurSSTVisdoneingrayscaleforthemostpart,afewhamshaveexperimentedwithcolorSSTV.CharacteristicsThisbandbehaveslikethe16-meterand15-metershortwavebroadcastbands,whichlieclosetoitinfrequency.Thissystemhasanexternallinearamplifier(aprecisionradiotransmittingamplifier)forgeneratinghigh-powersignalsonsomefrequencies.TipHasanyonetoldyouthatyoucan’tworkDX(far-awayforeignstations)on40meterswithoutahigh-poweredlinearamplifier?Yourchoiceofriglocationwillbelimitedifyouwantto“runthemax”andoperateinso-calledQRO(highpower)mode.ImagesandVideoRadioamateurshavebeensendingandreceivingimages,bothfixedandmoving,fordecades.Forthatreason,andalsobecausethehoursofdarknessdon’tlastaslongduringthoseseasons(springandsummer)astheydointhefallandwinter,you’llfind160metersmostusableoncold,darknightsinNovemberthroughFebruary,when,alongwithawoodfireandacupofcoffeeorhotchocolate,hamradiooperationcompletesagreattrio!AllocationsbyModeThe160-meterbandisn’tbrokendownintosegmentsbymode.ThisfactbecomesapparentifyourewritetheaboveformulaasPowerGain(dBd)=PowerGain(dBi)−2.15DirectivityPlotsYoucanportrayantennaradiationpatterns(forsignaltransmission)andresponsepatterns(forreception)usinggraphicalplots,suchasthoseinFig.Here’saTwistOnceinawhileyou’llhearsignalsthatfollowtwopaths,onesignalgoingalongageodesicarc(greatcircleroute)theshortwayaroundtheearth,andtheothersignalgoingalongageodesicarcthelongwayaround.Ifyouplantouseawaveguide,youmustkeepitsinteriorcleanandfreefromdustorcondensation.Onagreatcirclemap,anygeodesicfromthelocationatthecentershowsupasastraight,radiallinethatrunsoutfromthecentertothelocationinquestion.AtA,theH-plane(horizontalplane)plotasviewedfromhighabovetheantenna.Evenwhenathunderstormisseveralkilometersaway,itcan“chargeuptheatmosphere”enoughtoelectrifyalongwireantennatoanastonishingextent.Actually,itdoesn’thave100-percentcertainty,butitgetsagoodcluebycomparingthenumberofmarkbitstothenumberofspacebitsineachseven-bitcodecharacter.5-6A),hasasinglediodethat“chopsoff”halfoftheACcycle.Muchofthedielectriciscutawaytominimizethelineloss,whilemaintainingconstantconductorseparation.Figure5-11showsthe“tanglewiregarden”underneathmyhamradiostation.GroundSystemsEnd-fed,quarter-wavelengthantennasrequirelow-lossRFgroundsystemstoperformefficiently.Mostbalanced-linetransmatchesusespecialtransformerscalledbaluns(acontractionoftheexpression“balanced-to-unbalanced)tointerfacecoaxwithtwo-wireline.Thisstateofaffairsrequiresthattheantennasystempresentanonreactiveload(nocapacitanceorinductance,butonlytheesotericphenomenonknownasradiationresistance)ofacertainvalue,usually50ohms.IfyourQSOistakingplaceforthebenefitofathirdpartyanditalsohappenstobeaninternationalcommunication,thenyoumustalsoidentifytheotherstation.Figure3-5showstheoperatingscreen.(Atthetimeofthiswriting,frequenciesbelow9kHzwerenotlegallyallocatedforanypurposeintheUnitedStates.)Waveguidepropagationoccursalongwithsurface-wavepropagation,whichyoulearnedaboutinChap.ThedeviationobtainablewithFMisgreaterforagivenoscillatorfrequencythanthedeviationthatyougetwithPM.Thetapconnectsdirectlytoelectricalground.Thefrontendshouldalsohavethegreatestpossibledynamicrange.Thecarrierphaseremainsconstantduringtheentirelengthofanysinglebit,andmight(ormightnot)shiftby180degrees,orahalfcycle,forthenextbit.SpecificationsInadditiontolookingoverthefeaturesthatvariousradioshavetooffer,you’llwanttoknowhowwelltheydotheirjob.Avoidbackfeedatallcosts!Warning!Noise,Noise,Noise!Inwirelesscommunicationspractice,RFnoisethatcomesfromoutsideiscalledexternalnoise.Thishobbyiscalledshortwavelistening(SWL).You’llwanttocheckyourlocalzoninglawsconcerninglargeantennas,andmakesurethatnoneofyourneighborswillhateyouwhentheyseeamatrixof2-meterYagissproutinyourbackyard.Thenthemainsensitivity-limitingfactorbecomesnoisegeneratedwithinthereceiver.TheoriginatorsofDigiPanwroteitfordigitalcommunicationinphaseshiftkeying(PSK),apopularmodeamonghamradiooperators.Afriendloanedmeahomemadevacuum-tube,2-meterAMrigthathadaboutthesamedimensionsandweightasasmallrefrigerator(andprobablygobbledupasmuchelectricitytoo).Figure6-9showsthewholeantennawiththelowermosttwosectionsextended.Forordinarywire,youmustincorporateavelocityfactor,v,of0.95(95%)toaccountforthiseffect.CharacteristicsThisband,likethe31-metershortwavebroadcastband,liesina“transitionzone”asyougoupinfrequency,wherethepropagationbeginstogetbetterinthedaytimethanatnight.You’llhaveto“tweak”theelementlengthsalittletogetthelowestSWRpossibleat24.940MHz.TipWithaground-planeantenna,youcancuttheradialsto1/4wavelengthandthenleavethemalone,trimmingonlytheradiatingelement.Figure2-3showstheeffect.5-9B).Solarflaresemitcountlesshigh-speedatomicparticlesthathurtlethroughspaceatasmallfractionofthespeedoflight,usuallyreachingtheearthseveralhoursaftertheoccurrenceoftheflare.Thisisattributabletothehigherdielectriclossofpolyethylenecomparedwithair.•Bandscanning—Inachannelizedreceiversuchasyou’lloftenfindatVHFandUHF,bandscanningcansaveyoualotoftedioustuningandhuntingforsignals.Iftheelectricfluxlinesrunperpendiculartotheearth’ssurface,youhaveverticalpolarization.Moreover,nosharingprovisionsimpedehams’fullenjoymentofit.Variouscommerciallymanufacturedshortwavereceiversexistonthemarket,ranginginpricefromunder$100tothousandsofdollars.CoolFactoids“Shortwave”radiocommunicationbymeansofF-layerpropagationcanusuallybeaccomplishedbetweenanytwopointsontheearthwithinacertainrangeoffrequenciesbetween5MHzand30MHz.Thebottomoftherange,atanygiventime,iscalledthelowestusablefrequency(LUF).TheSWRcanequal1:1onlywhenthecurrentandvoltagestayinthesameproportionseverywherealongtheline.DishMostpeoplearefamiliarwithdishantennasbecauseoftheirwidespreaduseinconsumersatelliteTVandInternetservices.Itestedthewalloutletunderneaththeworkbenchtoensurethatthe“thirdprong”actuallygoestotheelectricalgroundforthehouse.Figure3-8showshowthisworksinHamScope.You’llfindthisfeatureincontemporaryradiosforuseonanyofthehambands.Youhaveatransceiver,anantennatuner,acomputer,andaninterfaceunitthat’llletyouusesomeofthosefancydigitalmodesontheHFbands!You’veunpackedtheequipmentfromtheboxes.Onanafternoonwhensignalswereabundantonthe27-MHzCitizensBand(CB)andalsoonthehamradio10-meterband,Iheardnothinghereotherthanafewstrangesounding“blips.”Ifyou’vedonemuchoperatingonthehamradio12-meterbandat24.890MHzto24.990MHz,orifyouhappentobeoneofthoseCB“freebanders”whospendsalotoftimeontheairaround27MHz,youhaveagoodideaofwhattoexpectintermsofpropagationconditionsonthe11metershortwaveband.6-11).Propagationcantakeplaceoverthedarksideoftheearth,butsometimestheFlayersarenotsufficientlyionizedatnighttoreturnsignals.8,you’lllearnabouttheantennasthathamradiooperatorsfavor.Yousettheloop’soptimumreceivingfrequencybyadjustingthecapacitor.Thepotentiometermarked“balance”mustbeadjustedexperimentallytogetoptimumreceived-signalaudioquality.InthesimplesttypeofACgenerator,acoilofwire,attachedtotheshaftofthecombustionengine,rotatesbetweenapairofpowerfulmagnets.Adishantennamustmeasureatleastseveralwavelengthsindiameterforproperoperation.ThecommercialFMbroadcastbandat88MHzto108MHzintheUnitedStatescanbeaffectedbyductinginadramaticwayeverynowandthen.FIGURE2-12AtA,aspectraldiagramofpure,60-HzEMenergy.Hamswillsaythat“thebandisgoingout,”orthey’lltalkabout“QSB”(fading).Asamatteroffact,anyinstantaneousphasechangeshowsupasaninstantaneousfrequencychangeandviceversa.Everypulsehasthesameamplitudeandthesameduration,butthetimeintervalbetweenthemchanges.IdefertotheARRLinthiscategory;nooneknowsmoreaboutthepublic-serviceaspectofhamradiothantheydo.TABLE4-3SuballocationsintheUnitedStatesforthe40-meterband(7.000MHzto7.300MHz)asofMarch2012.Ahalf-wavedipolespansonlyabout8metersfromendtoend;ifyoucutitfor18.118MHzatthebandcenter,you’llgetagoodmatchto50-ohmor75-ohmcoaxoverthewholeband.Ifyougetlucky,youmighthearaLowFERortwosendingexperimentalsignalsfromafewhundredkilometersaway.OnlyGeneral,Advanced,andExtraClassoperatorshaveaccesstothischoicespanoffrequencies,buttheycanuseuptothefulllegallimitoftransmitteroutputpower(1500wattsPEP)throughout.Arepeaterreceivesasignalonaparticularassignedfrequency,andretransmitsitatthesametime,usuallyinthesamehambandbutonadifferentassignedfrequency.Alwaystrytobalancetheloadsamongmultipleoutletsinageneratorthathasmorethanoneoutlet.FIGURE7-4Asmallloopantennawithacapacitorforadjustingtheresonantfrequency.Bipolartransistors,whichcarryhighercurrentsthanFETs,generatemorecircuitnoisethanFETsdo.However,theeffectisnotquiteaspronounced.5-1asareference.Longquadantennasarepracticalatfrequenciesabove100MHz.Atfrequenciesbelowapproximately10MHz,quadantennasbecomephysicallylargeandunwieldy,althoughsomeambitious(anddaring)hamshaveconstructedquadstoworkatfrequenciesdownto3.5MHz.AntennasforUHFandMicrowaveFrequenciesAtfrequenciesabove300MHz(wavelengthslessthan1meter),high-gain,multielementantennashavereasonablephysicaldimensionsandmassbecausethewavelengthsareshort.AtB,slopedetectionofFM,showninthefrequencydomain(agraphofamplitudeversusfrequency).You’llgainagooddealofoperatingsavvyinahurry.Onceinawhile,you’llhearstationsasfarawayas1000kilometersduringthedaytime,butthisbandreally“shines”atnight,whenyoucanexpecttohearstationsfromallaroundtheworld.Alongwiththediscussionsinthischapter,anyoneofthesemapscanhelpyoufindoutwhetherornotyoushouldexpectgoodshortwavepropagationfromanygiventransmittinglocationtoanygivenreceivinglocation.IfyouwantreasonableefficiencyinanantennawithalowRRvalue,youmustdoeverythingyoucantominimizeRL.AfewpioneeringhamsstartedusingAMTORintheearly1980safterhavingadapteditfromthecommercialmodecalledsimplexteleprintingoverradio(SITOR).Ageodesicwillnearlyalwaysshowupasacurveonanordinarymap(agoodexampleisthegreylineitself,whichisalwaysagreatcircle),andyoumighthaveahardtimeguessingthegeodesic’spositionbetweenyourlocationandtheplacewherethetransmittedsignaloriginates.Iftheselines(notrealthreadsorobjectsofanysort,buttheoreticalartifacts)runparalleltotheearth’ssurface,youhavehorizontalpolarization.Adeep-cyclemarinebatterywith35to50ampere-hoursofcapacitycanlastforafulldayortwowithaQRPstationcomprisingaradiosuchastheTenTecArgonautorequivalent.Warning!TheSunspotCycleForcenturies,astronomershaveknownthatthenumberofsunspotschangesfromyeartoyear,monthtomonth,anddaytoday.ForTechiesOnlyIfyouhaveaccesstoaspectrummonitor,suchasthesortyoumightfindinahigh-endHFcommunicationsreceiveroraprofessionalelectronicslab,youcanuseittomakesurethatyoustayinsidetheallocatedchannel.Thiscanhappenbecausethenetworkgetsoverloadedwithtoomanyusersatasingletime,orpartofitgetsphysicallycompromised(byahurricaneorwildfireforexample).Ifareceiverhasafrontendthatcan’thandlestrongsignals,desensitization(amomentarylossofsensitivity)willoccurwhenastrongsignalcomesinattheantennaterminals.Thedestination-stationoperatordoesn’thavetodirectlyattendtotheequipmentinorderforapackettobereceived;thecomputercanstoreit.Youcanbuildorbuyashortwaveradioreceiver,installanoutdoorwireantenna,andlistentosignalsfromallaroundtheworldinanactivitycalledshortwavelistening(SWL).Thekey-down(audiotone)conditioniscalledmark,andthekey-up(silent)conditioniscalledspace.Asmallloopantennawithatuningcapacitororpreamplifiertoboostthesignallevel,usedindoorsnexttotheradio.•YoucanusuallygetawaywithamagneticmountatthebaseofaVHForUHFmobileantenna(forexample,theoneshowninFig.Thatway,thereceivingstationcanbe“prettysure”thatitgoteachbitcorrect.Asyoucanimagine,engineersmustspendalotoftime“tweaking”thedimensionsofsuchantennastooptimizetheirperformance.Thesplitgenerallygetslargerastherepeater’soperatingfrequencyincreases.Forexample,aVLFsignalcominginat17kHzwouldshowupinthereceiverat3517kHz(3500+17)andalsoat3483kHz(3500−17).Becauseitcangetcrowded,thisbandoccasionallyharborspeoplewhogetimpatient,andevenrude,withtheirfellowoperators.EventhemostconcertedeffortsrarelyreduceRLtolessthanafewohms.Theextentofthehazard,ifany,posedbysuchexposurehasnotbeenfirmlyestablished.Someofthehitswillleadyoutomapsthatportraythecontourofthegreylinewherethesunliesonthehorizonasseenfromtheearth’ssurface.Ideally,arepeatershouldbelocatedinahighplace,suchasonamountainortallbuilding(Fig.Ifthecurrentfluctuates,sodoestheoutputvoltage(thehigherthecurrent,thelowerthevoltage).Intheory,Morsecode,whichhamscallCW(forcontinuouswaves),isabinarydigitalmodeinwhichthesignalalwayshaseitheroftwowell-definedstates:full-on(keydownormark)orfull-off(keyuporspace).FIGURE5-9AtA,acapacitor-inputfilter;atB,achoke-inputfilter.Ifthe10-to-11-meterzonehasanylifeatall,there’llbeplentyof“goodoldboys”havingfunintherangeoffrequenciesthatIcallthe“ChaosBand.”Ifyouhearsignalsaround27MHz,youcanhavereasonableconfidencethatthe10-meterhambandisopen,whetherornotanyoneistakingadvantageofit!Youcan,withsomepatience,havesomecoolexperiencesonthat“magicband.”TheContestConundrumIfyouoperateonweekends,you’lloftenhavetodealwithconteststhatwillaffectyourchoiceofband,frequency,and/ormode.•Disconnectalloutdoorantennasfromelectronicequipment,andconnectthoseantennafeedlinestoasubstantialearthground,atalltimeswhenyouaren’tusingyourstation.Afull-sizequarter-waveverticalantennameasuresabout7meterstall.Thisfeatureiscalledselectivesquelching.YouadjustthefrequencyoffsettogetspecificstandardAFnotes(suchas2125Hzand2295Hzinthecaseof170-Hzshift).Cutthepieceoflumbertoalengththatequalstheinsidewidthofthesash.FIGURE5-15Ifyouconnectanoscilloscopeintoaradioreceiverandlistentosferics,you’llseeadisplaythatlookssomethinglikethisdrawing.MylandlordhadagoodattitudewhenIaskedhimifIcouldputanantennaontheroof.HamswhoholdGeneral,Advanced,orExtraclasslicensesmayuseanyfrequencybetween1.800MHzand2.000MHz.Thewholebandisoff-limitstoNovice,Technician,andTechnicianPluslicenseholders.Radiohamshavethewholebandtothemselves,andcanuseuptothelegalpowerlimit.ThefirsttimeItriedthattrickasaNoviceclassoperatorin1966aftergettingatipfrommymentorBill,W0GLE,IsentaCQandsnaggedsomeinstantDX!Well,okay,VE3(Ontario),frommystationinMinnesota—butatthetime,itthrilledmehalftodeath.Thefadingbecomesmorepronouncedastheoperatingfrequencyincreases.Thebandspreadscalehada“slide-rule”geometrywithmultiplescales,butitgaveaccuratereadingsonlywhenthemaintuningdialwassetatspecificpoints.Asofthiswriting,youcanreaddataaboutsolaractivitybyvisitingthewebsiteoftheAmericanRadioRelayLeagueatwww.arrl.orgLookforalinkdealingwiththe“solarupdate.”AtmosphericNoiseElectromagneticnoiseisgeneratedintheatmosphereofourplanet,mostlybylightningdischargesinthundershowers.Iftheeffectbecomessignificant,itcancauseablueorpurpleglowcalledacoronathatcanbeseenatnight.7.•ThesquelchsensitivityofaVHForUHFFMreceiveristhesignallevel,inmicrovoltsattheantennaterminals,neededtokeepthesquelchopencontinuously.Toavoidthisproblem,makesurethatwhenyoutransmitaPSK31signal,yousettheaudiotonestoafrequencyofatleast2000Hzsothatalltheaudioharmonicsfallfaroutsideyourtransmitterfilterpassbandandgetsuppressed.1,electricandmagneticfluxlinessurroundallcurrent-carryingwires.Yourtransmittercannotputoutmorethan200wattsPEP.TheGeneralClassexamgoesintomoredepththantheTechexam,particularlywhenitcomestoelectronicstheoryandcommunicationspractice.YoucanalsoshoparoundinconsumerelectronicsandAmateurRadiomagazines.TransmatchTheoutputimpedanceofaradiotransmitter,ortheinputimpedanceofareceiver,shouldideallybematchedtotheantenna-systemimpedance.MobileBandOptionsFormobileoperation,theVHFandUHFbandsgenerallyworkbetter,fromatechnicalstandpoint,thantheHFbandsdo,especiallytheonesat1.8MHz,3.5MHz,and7MHz.That’sbecause,asthewavelengthgetslonger,theminimumphysicallengthorheightofanefficientantennaincreases,makingaseries-connectedinductancemandatory.Communicationsengineersandradiohamsusewaveguidesatultrahighandmicrowavefrequencies(300MHzandabove)tocarrysignalsfromtransmitterstoantennas,and/orfromantennastoreceivers.Internetsitesandcontentchangeonanalmostdailybasis,butIfoundthislinkvalidandnoteditinDecemberof2013.Whenthemotorlosespower,dothemotor’sverticallinescurvebacktowardtheleftbeforetheyvanish?Asyouincreasethenumberofstates,thefidelityimproves,butthesignalgetsmore“complicated.”Figure1-14DshowsanexampleofeightlevelPCM.ForTechiesOnlyHoweverexoticitmightseematfirstthought,spread-spectrumtechnologyhasexistedforquitealongwhile.IntermodcanalsodegradetheS/Nratiobygeneratinghash,aformofwidebandRFnoise.Thespecificationappliestounidirectionalantennas,andalsotobidirectionalantennasthathavetwofavoreddirections,oneoppositetheotherinspace.Thetest,asyoucanguess,dealswithsomefundamentaltechnicalstuffaswellasimportantregulationsimposedbytheFCC.Youmightpreferacertainrangeofaudiofrequencies,suchas600Hzto700Hz;butifyourradiocanheareverythingthatproducesbeatsignalsbetween500Hzand1000Hz,thenyoucancopythatstufftoo.Butratherthanhavinginfinitelymanypossiblestates,thenumberofstatesequalssomepowerof2,suchas22(fourstates),23(eightstates),24(16states),25(32states),26(64states),andsoon.LargeYagisarepracticalon219.000MHzandabove;moreexoticantennas,suchashelicaltypes,horns,anddishes,appearat23centimetersandshorterwavelengths.IfyoutunethereceiversothattheFMunmodulated-carrierfrequencyliesneareitheredge,orskirt,ofthefilterresponse,frequencyvariationsintheincomingsignalcauseitscarriertoswinginandoutofthereceiverpassband.Ifarepeatertransmitson147.00MHzandreceiveson147.60MHz,thenyou’llwanttosetyourradiototransmiton147.60MHzandreceiveon147.00MHz.Usersofthatrepeaterwouldcallitsfrequencycombination“60/00.”Becauseyoumusttransmitonafrequencyabovetheoneonwhichyoureceive,youcallthatsplit“positive”(specifically,+600kHz).Lawyersmight“splithairs”onthisissue,butyoucancertainlyuseabitofgoodsensehere.However,whenyouvarythephaseofawaverapidly,you’llgetvariationsintheinstantaneousfrequencyasanindirectconsequence.Thesimplesthamradiostationhasatransceiver(transmitter/receiver),amicrophone,andanantenna.Ingeneral,asyouincreasethenumberofelements,theforwardgain,thef/bratio,andthef/sratiosallincrease.Mostcoaxialcablesusebraidedcopperfortheshield,butsomecableshaveasolidmetalpipesurroundingthecenterconductor.GroundPlaneAground-planeantennaisaverticalradiator,usually1/4wavelengthtall,operatedagainstasystemof1/4-wavelengthconductorscalledradials.You’lllearnmoreabouttransmissionlineslaterinthischapter.Afast-scanamateurtelevisionsignalhas30completepictureframespersecond.Separatethewiresbypullingthemapartalongtheentirelengthofthecordsothatyougetaphoneplugwithtwowiresattached,formingalittledipoleantenna.SfericsprobablyalsooccuronSaturn,andperhapsonUranus,Neptune,Venus,andMarsaswell.EventheTechnicianClasslicenseforexperimentersatthehigherfrequenciescarrieda5-wpmrequirement.Forthepurposesofthisdiscussion,let’scallanRFpoweroutputof25wattsormoreQRO,andanythinglessthan25wattsQRP.Third,half-waverectificationputsastrainonthetransformeranddiodesbecauseitworksthesecomponentshardduringhalftheACcycleandletsthem“loaf”duringtheotherhalf.TABLE8-2PhoneticRepresentationsforLettersoftheEnglishAlphabetCallingaStationImaginethatyouhearsomeonecallingCQonSSB,orendingacontactwhileleavingopenthepossibilityofhavinganotherone.Theline-of-sightwaveconsistsoftwocomponentscalledthedirectwaveandthereflectedwave.Four-wiresufferslessthantwo-wirelinefromtheeffectsofnearbyobjectsbecausemoreoftheRFfieldstayswithintheline.Aharmonicisawhole-numbermultipleofthefundamentalfrequency.Thetwoprimary“flavors”areMFSK16with16frequencies,andMFSK8witheightfrequencies.Theearth-ionospherewaveguidehasaminimum-frequencycutoff(lowerlimit)ofaround9kHz.Atlowerfrequencies,signalsdon’tpropagatewellbecausethewavelengthistoolongtolettheearthandtheionospherefunctionproperlyasawaveguide.31MetersCoveringthehalf-megahertzrangeof9.400MHzto9.900MHz,the31metershortwavebroadcastbandliesneartheAmateurRadio30-meterband(10.100MHzto10.150MHz).Ofcourse,forslowtypists,thespeedcomesoutslowerthanthat.Yes,Iusedtomeasuremysendingandreceivingspeedstothenearestwordperminute!Iguessinretrospectthathabitmighthavequalifiedasanobsession.•WithQRP,yourradiatedsignalisnotlikelytocauseRFItosensitiveelectronicdevicesthatmightexistonthepremises(suchasheartpacemakers!).Alsoitismorelikelytooccurattheendofapointedobject,suchastheendofawhipantenna,thanonaflatorbluntsurface.ForFM,aswithFSKandPSK,it’s100percent(1to1).Aswiththelower-frequencybands,conditionspeakinthewinterwhenthunderstormsoccurlessoftenandthenightslastlonger.Ithasaperiodofapproximately11yearsfrompeaktopeak.Youcanfindthisstuffinavarietyofforms.Largerlinears(providingmorepower)haveessentiallythissameconfiguration,butmightneedtwoorthreelargepowertransistorsconnectedinparallel.Whenyouemployso-calledinductiveloadingthisway,youlosemorepowerinthegroundsystemthanyouwouldloseifyoufedafull-size,quarter-wavelengthelementdirectlyatthebase.HeadsUp!AllcommunicationssystemsshouldincorporatesomeformofprotectionagainsttheeffectsofanEMP.IinviteyoutogetonYouTubeandsubscribetomychannelrightnow!FIGURE6-14TheActiveTuningAntennaSystem(ATAS)formobileusewithYaesuradiossuchasmyFT-857D.Avoidexpressionsthatneedcommas,semicolons,orotherspecialsymbols.1-18DorEliesinthenonlinearityofthesemiconductordevices.Goodconditionscansometimesexistonthisbandduringthespring,summer,andfallmonths,especiallyinplacessuchastheWestCoastoftheUnitedStateswherethunderstormsrarelyoccuratanytimeofyear.Inmyarrangement,theradiositsontopofthetransmatch.Buyacarbon-monoxidedetectorifyoudon’talreadyhaveone,andplaceitinyourhouseneartheroomswhereyousleep.Eventhebestoperators,whocansendandreadCWataround90wpm,communicateatonly75bps.Irun10wattsoutputonCWand7wattsoutputonPSK31,mytwofavoriteoperatingmodes,frommyhomestation.Thenyouintroduceanunmodulatedsignalwithacalibratedgenerator.RadiationResistanceWhenRFcurrentflowsinanelectricalconductor,suchasawireoralengthofmetaltubing,someEMenergyradiatesintospace.You’llfindexplanationsofthesesystemelementslaterinthischapter.Thiscircuitproduces5dBto10dBofusefulsignalgain,dependingonthefrequencyandthechoiceofFET.FIGURE1-18A-BAtA,envelopedetectionofAM,showninthetimedomain(agraphofamplitudeversustime).IfthewirecarriesconstantDC,theEandMfieldsremainconstantandsteady.SometimesyoucanworkgreatDXon30metersduringtheday,andsometimesyoucandoiton20metersoreven15metersatnight.Theoutputofthescannergoestoamodemthatconvertsthebinarydigitalpulsesintoasignalsuitablefortransmissionoveryourradio.Iconnectedagroundwirefromtheshieldpartofthecoaxialcableatthebasemounttothetruckbedusingashortwirewithascrew,wingnut,andlargewasher.Doyouwonderwheretheradiowavelengthdesignatorscomefrom,andhowaccuratetheyreallyare?Theamplitudelevelsarerenderedasbinarynumbersfrom000(equivalenttothedecimalnumber0)to111(equivalenttothedecimalnumber7).Openthewindow,setthewoodwiththecablesdowninthebaseofthesash,andthenclosethewindow,slidingitfirmlydowntoholdthewoodinplace.Someengineersusethetermright-handinsteadofclockwiseandthetermlefthandinsteadofcounterclockwise.I’vedisplayedMFSK16fromW1AWbulletintransmissionsunderconditionssobadthatIhadtroubleattimestellingthatthesignalwasstillthere.Ifyoulike,youcanenlisttheassistanceofautomaticfrequencycontrol(AFC)thathelpstheprogramgetonthecorrectfrequencyforoptimumdecoding.Anyend-fedwire,nomatterhowlongorshort,needsagoodRFgroundatitsfeedpoint.BaudotTeleprintersTheoldestRTTYcodeiscalledBaudot,andallowsforprintingofuppercaselettersofthealphabet,numerals,andcommonpunctuationmarks.ThepreferredmodesareCWandWSJT.Slow-scantelevision(SSTV)accomplishesthisfeatinpartbyreducingtherateatwhichpicturesgetgeneratedandsent.It’sasolidaluminumbakingsheet.(Ipreferthespectrummodewiththisprogrambecausethedashedlinesextendallthewayupanddownthedisplay;inthewaterfallmodetheydon’t.)You’llwanttomovethedashedlinesaroundwithyourmouseuntiltheycoincideasnearlyaspossiblewiththesignalboundaries.Thenewsmediahavepickedupwithavengeanceonthistrendanditspossibleconsequences.Whenendingatransmission,say“Over?”asifaskingaquestion.Ignoranceisbliss:Inthe1960sand1970s,theproblemwasfarworse.Checkyourlocalnewspaper’sclassifiedadsection.TheACfrequencyinasimplegeneratordependsonlyonthespeedofrotation.1-1.AllocationsbyLicenseClassExtraClassoperatorscanusethewhole40-meterband,subjecttomoderestrictions.•Receiverincrementaltuning(RIT)letsyouadjustthereceiverfrequencyafewkilohertzupordownfromthetransmitterfrequency,whichremainsconstantasdeterminedbythemainvariablefrequencyoscillator(VFO)orsynthesizer.They’llprovideallsortsofadviceandinsights—andthey’llprobablytrytogetyouinterestedintheirhobbyaswell.Somelinearsaredesignedtosupply1500wattsoutputfora50-percentdutycycle,typicalCWandSSB.TechNoteMostradiosmanufacturedsinceabout1995haveaCWoffsetequaltothepitchofthesidetoneasyousend.GalacticnoisewasfirstnoticedandidentifiedbyKarlJansky,aphysicistworkingfortheBellLaboratoriesinthe1930s.EngineerscallRRtheradiationresistanceoftheantenna.ThenlaunchDigiPanandfollowthesesteps,inorder.Agoodrepeaterwillincreasetherangebetweenmobileandportablestationscomparedwithdirect,orsimplex,communications.Thesamethingwillhappeneventually,ifyougatherenoughgearinyourhamshack.TechTidbitIfyouplaceaflatreflectingscreenbehindthearrayofdipolesinFig.Ifyoucangetitupatleast5meters,it’llworkokay.Inawell-designedfrequency-hoppingsystem,thedwelltimeisshortenoughsothatanunauthorizedlistenerusingareceiversettoaconstantfrequencywon’tnoticeit.CharacteristicImpedanceTheratioofthesignalvoltagetothesignalcurrentinatransmissionlinedependsonseveralthings.Inthisexample,thewaveatAhashalfthefrequencyofthewaveatB.Thatmeansyou’llneedoutletswiththreeslotsaswellaspowercordswiththreeconductorsandthreeprongsintheirplugs.Thepowergaininthemainlobesofastraightlongwiredependsontheoveralllengthoftheantenna:thelongerthewire,thegreaterthegain.(Ofcourse,inthateventIwon’tpowerupthehamshackatalluntilthefloordriesout!)3.Conversely,computerengineersand“powerusers”aremorelikelytogetinterestedinhamradiothanpeoplewhoavoidcomputers.Foronething,withthenon-CWmodes,youreadtheotherperson’sstuffandsendyoursonakeyboard,ratherthanlisteningtoaudiotonesandmanipulatingakeyerpaddleorstraightkey.Thisprecautionensuresthatthegeneratorwilloperateatmaximumefficiency.Theelementsallreceivetheirportionsoftheoutgoingsignalinphaseandatequalamplitudes.However,youcanincreasethedeviationofanyFMorPMsignalwithafrequencymultiplier.Themostcommonwaytoachieveselectivesquelchingistheuseofasubaudible(below300Hz)tonegeneratororaudiotone-burstgeneratorinthetransmitter.FIGURE7-5AtA,thecorrectmethodforRFgroundingofmultiplehardwareunits.TheIFbandpassfiltercanbeconstructedforuseonafixedfrequency,allowingsuperiorselectivityandfacilitatingadjustablebandwidth.Theloopcontainsseveralturnsandcanhaveadiameterofabout1meter.Inthiscase,allthedrivenelementsareidentical,andarespacedathalf-wavelengthintervalsalongthephasingharness,whichisaparallel-wiretransmissionlinewithahalf-twistbetweeneachelementtoensurethatalltheelementsoperateinphasecoincidence(exactlythesamephase).Ahalf-wavelengthlooppresentsahighradiationresistanceatthefeedpoint.Theincomingsignalispickedupbytheantennaandfedtothereceiver.Inanycase,theallowablebandwidthislimitedontheHFbandsbyFCClaw,andthatconstraintplacesapracticalmaximumonthecommunicationspeed.NodesandLinksFigure3-9Bshowsagenericexampleofhowapacketradiomessagegetsrouted.Thiseffectmakesthesolarfluxusefulforpropagationforecasting:Asuddenincreaseinthesolarfluxindicatesthationosphericpropagationconditionswilllikelydeterioratewithinafewhours.BandwidthWhenyoufrequency-modulateacarrierwave,yougetsidebandsaboveandbelowthecarrierfrequency,justasyoudowithAM.Withthedipoleorientedsothatitsconductorrunsperpendiculartothepageorscreen(asyoulookatitinthisbookore-reader),andtheantenna1/4wavelengthaboveeffectiveground,theE-planepatternforahalf-wavedipoleresemblesFig.ThesepeoplesaythatthebestaudiofidelityinanFMradioreceivercomesonlyasaresultofdirectFMusingreactancemodulation,suchastheschemeshowninFig.HamradiooperatorsuseSSBemission,requiringareceiverwithalocalinternaloscillator,butbroadcaststationsuseAMemission,andyoucanbringtheminwithasimpleenvelopedetector.Youcanusethistableasaguideasyounavigateyourwaythroughthelabyrinthoffrequenciesandwavelengthsthatagoodallwaveradioreceivercan“hear,”andthensome!Gotowww.fcc.gov/encyclopedia/radio-spectrum-allocationYoucanchooseeitherWordorPDFformatsforofflineviewing.Thesetransmissionlinesworkwithsignalswhosewavelengthsmeasuremillimetersorcentimeters.You’llseeapairofdashedlinesindicatingthestandardpointsfortheMFSK16frequencyboundaries.90MetersIntherangeoffrequenciesfrom3.200MHzto3.400MHz,signalspropagatebetteratnightthanduringtheday,justastheydoonthe120-meterbandandthestandardAMbroadcastband.Inaradioreceiver,sfericscauseafaintbackgroundhissorroar,punctuatedbyburstsofsoundwecall“static.”Figure5-15showsanexampleofthisnoiseasitwouldlookonthedisplayofalaboratoryoscilloscopeconnectedintoaradioreceiver.Iattachedthemeter,showninFig.Figure3-1showsoneofthemostpopularofthesedevices,calledapaddle.Suchamountdoesn’tforceyoutodefacethevehicle,andyoucaneasilyandquicklyremoveitwhenyouwanttheantennaoffthevehicle(forexample,inacarwashorgarage).Ifyoudon’thaveanybigtreesonyourproperty,youcanputupmastsortowerstoserveasantennasupports.Youcan’tworkstationsthatyoucan’thear,andhumanmadenoisefromrogueelectricalapplianceshasproventhebaneofmyriadDXers’lives.YoucanfindphotographsandspecificationsfortheHallicraftersSX-130andsimilarvintageshortwaveradiosbyconductingtargetedInternetsearches.Sincethattime,Ihaven’treplacedthattunerforfearthatthesamethingwillhappenagain.InanAMsignalmodulatedat100%,you’llfindthat1/3ofthesignalpowerconveysthevoiceinformation,whilethecarrierwavegobblesuptheother2/3ofthepower.Keepthemicrophonegrillefacingyourmouthataslightangle,twoorthreeinchesfromyourface.Asyoumakeyourwireantennalonger,thedangerincreasesbecauseitwillreadilyaccumulatemassiveelectrostaticcharges.Millionsofpeopleallovertheworldenjoyit.ThisreductionfurtherreducesthebandwidthofSSTV.Atypicalpreselectormakesthereceivermostsensitivewithinafewpercentagepointsofthedesiredsignalfrequency.Theblackdotsrepresentsubscribers(endusers)withpacketcommunicationscapability.Thefeedpoint,wherethetransmissionlinejoinstheradiatorandthehuboftheradialsystem,iselevated.Thefluctuatingvoltageacrossthevaractorcausesitscapacitancetochangeinaccordancewiththeaudiowaveform.WestMountainRadio,atthetimeofthiswriting(2014),offerssoftwareformorethan20exoticdigitalmodes!Utility-OperatedPowerSuppliesAfixed-stationpowersupplyprovidesyourhomestationwiththepropervoltagesandcurrentsfromtheACutilityline.IfyouhaveagoodInternetconnection,DigiPanwilldownloadandinstallinaminuteortwoonanycomputerthatrunsWindowsXP,Windows7,orWindows8,althoughsomeoftheprogram’smoreexoticfeatureswon’trunonWindows7or8.Iassumethatyoualreadyknowsomeelectricityandelectronicstheory,andyou’vepickedthisbookupbecauseyouwanttotakeyourhobbytonewlevels.FIGURE6-2Amobile2-meterFMtransceiver.Thesecurrentshaveabroadbandnature.Youcan,ifnecessary,proveyourworthinthepublicservicearenaduringandafteranaturaldisaster,suchasahurricane,flood,wildfire,orearthquake.Inadditiontotheprogramming,ARQmandatesareliable,fasttransmit/receive(T/R)switchatbothendsofthecircuit.Allyou’llhearis“monkeychatter,”theresultofthehighervoicefrequencycomponentscominginatlowfrequenciesandviceversa.Forastraightwireradiator,thelengthLm,inmeters,atadesignfrequencyfo,inmegahertz,foracenter-fed,half-wavelengthdipoleisapproximatelyLm=143/foFIGURE7-2Basichalf-waveantennas.Onthe“lion’sshare”ofthe80-and-75-meterband,goingfrom3.600MHzto4.000MHz,voice(alsocalledphone)andimageemissionsareallowed.Pulse-IntervalModulationEvenifallthepulseshavethesameamplitudeandthesameduration,youcanobtainpulsemodulationbyvaryinghowoftenthepulsesoccur.Thefeedlineisawaveguidethatmeetstheantennaatthenarrowestpoint(throat)ofthehorn.IheardsignalsallthroughtheVLFband,withthelowestonesaround13kHz.Thetrickworkedallthewayuptoabout60kHz,beyondwhichpointtheaudiocircuitsintheT-4Xdidn’tworkverywell.However,neitherMcGrawHillEducationnoritsauthorsguaranteetheaccuracyorcompletenessofanyinformationpublishedherein,andneitherMcGraw-HillEducationnoritsauthorsshallberesponsibleforanyerrors,omissions,ordamagesarisingoutofuseofthisinformation.Putonapairofrubberglovesandapairofshoeswithsolesthatwillelectricallyinsulateyourfeetfromthefloor.Thatwasmyexperience!Youcanlearntosendcodeonastraightkey,alsocalledatelegraphkey,withwhichyoumakethedotsanddashesbypushingdownonaleveragainstaspring-tensionbearing.AsontheHFNovicebands,Ihadtouseacrystal-controlledtransmitterthatputoutnomorethan75watts.Thisis(yourcallletters).”OnCW,send“QRL?”followedbyapauseandfinally“de”andyourcallsign.Ingeneral,ifyouhavearadiatingelementofafixedlength,youshoulddoeverythingyoucantominimizethelossresistance.SolarFlaresAsolarflareisaparticularlydramaticeruptiononthesun.Usually.CharacteristicsTheham15-meterbandbehavesliketheshortwavebroadcast13-meterband.YoucanalsofindMMTTYontheInternet,butyou’llhavetolookaroundabittofindthelatestversion.TheRFspectrumbreaksdowninbandsfromverylowfrequency(VLF)throughextremelyhighfrequency(EHF),accordingtothecriteriaoutlinedinTable1-1.SomeworkonlyonFM,whileotherscanworkallpopularmodesincludingCW,SSB,AM,andthedigitalmodes.AllocationsbyModeMostoftheHFhambandshavesegmentsdesignatedforusewithspecificmodes.Troposcatteralwaysoccurstosomeextent,regardlessoftheweatherconditions.TipShortwavelisteningcanhelpyoufindoutwhetherornotyouhaveenoughinterestinAmateurRadiotogoaheadandgetanoperator’slicense!Learningtheelectronicstheoryandregulationswellenoughtopassthehamradiotestswilltakesomework,butifyourheart’sinit,itwillseemlikeplay.1(Fig.ForNerdsOnlyDigiPanisn’ttheonlyprogramyoucanusetodisplaydirtyelectricityandotherEMspectraleffects.Thetransmittingstationsendsthreecharacters,andthenpausesandwaitsforaconfirmationfromthereceivingstation.WhenaDXstation,orsomeotherrarestationsuchasoneinvolvedwithaspecialevent,wantstoworkinsplit-frequencymode,itwillsendsomethinglike“UP”or“UP1”onCW,andgiveinstructionsinplainlanguageonSSB.FIGURE5-14MyportablegeneratorhastwoACoutlets.Signalsappearasvertical“bumps”calledpips.Evenonthemoon,whichhasnoionospheretoreturnradiowavestothesurfaceortoactwiththesurfacetoformawaveguide,LFwavesmightpropagateforover-the-horizoncommunicationbymeansofthesurfacewave.Usetelescopinglengthsoftubingfortheradiatingelement.Comparedwithold-fashionedanalogcommunications(wherethestateiscontinuouslyvariable),digitalmodesofferimprovedsignal-to-noise(S/N)ratio,narrowersignalbandwidth,betteraccuracy,andenhancedreliability.To“boneup”forthetest,IrecommendthatyouobtainandstudythetechnicalguidesfortheExtraClasslicensepublishedbytheARRL,aswellasmybooksTeachYourselfElectricityandElectronics,ElectricityDemystified,andElectronicsDemystifiedpublishedbyMcGraw-Hill.Ifyoucangetitupatleast10meters,you’llgetfineresults.Thetransmitterhasalistofchannelsthatitfollowsinacertainorder.ThenIworkedstationsallovertheplanetonmobileCWfromWyomingonvacationinFebruaryof2014.Infact,arenderedhardcopyfaxlookslikeaphotocopy.Youhaveagraceperiodtorenewyourlicenseifyouallowittolapse,althoughyoucan’ttransmitwithyourradiountilyougetavalidrenewedlicense.Unfortunately,asofthiswriting,alotofmediahullabaloohasbeenstirredupoverthedangerposedbythisphenomenon,butfew(ifany)countrieshaveundertakenseriouspreventivemeasuresonalargescale.Agridofwires,ascreen,orametalsheetisplacedabovetheearth’ssurfaceandorientedhorizontallytoobtaincapacitivecouplingtotheearth’sconductivemass.ThesensitivityisenhancedbecausefixedfrequencyIFamplifiersareeasytokeepintune.Figure3-4showsaclose-upofthethreetuningaidsinMMTTY.Thislimitationofliabilityshallapplytoanyclaimorcausewhatsoeverwhethersuchclaimorcausearisesincontract,tortorotherwise.Physicists,astronomers,andengineersrefertotheentirerangeofEMwavelengthsastheEMspectrum.TABLE4-1AmateurRadiobandsintheUnitedStates.Youmightevenneedtohaveanelectriciancometoyourhomeandinstalla234-voltsystemattheplacewhereyouplantobuildyourstation.IdiscusstheassetsoftheInternet,butemphasizethathamradiowillworkevenwhentheInternet,andallotherutilities,fail.Anotheradvantageisthefactthattheshield,whenproperlygrounded,keepsunwantedsignalsornoisefromgettinginfromsourcesrightnexttothecable.Figure5-3showsahypotheticalexampleforamodest-sizedyard.Youcanviewsunspotsthroughatelescopeequippedwithaprojectionsystemoradarkfilterovertheobjectivelensoropening(neverintheeyepiece).Onenight,asathunderstormswoopedacrosstheprairieandslammedintoRochester,Minnesota,Ihappenedtobeon40-meterCW,workingstationsatarespectablepace.Licensingrequirementsweredoneawaywith.Insertthemultimeter’sred(positive)probetipintothe“thirdhole”oftheoutletyouwanttotest,whileleavingtheblackprobetipintheextensioncordoutlet.Youmightevengofasterineffectat18WPMbecauseittakesextratimewhenevertheotherstationhastoaskyoutorepeatsomething.Thistypeofantennaissometimescalledacoaxialantenna,atermthatarisesbecauseofitsfeed-systemgeometry,notmerelybecauseit’sfedwithcoaxialcable.Becausetheparticlescarryanelectriccharge,theyconvergetowardtheearth’smagneticpoles,causingadisturbanceintheearth’smagneticfieldknownasageomagneticstorm.InSSBandothervoicemodes,say“CQCONTEST”threetimes,thenyourcallsignoncewithoutphonetics,thenoncewithphonetics,andthensay“standingby.”Onceyougetholdofacertainfrequency,youcanstayonituntilit“growsstale”andyoudon’tgetmanycallsanymore,oruntilthebandgoesout,oruntilyoucollapsefromexhaustion,oruntilthecontestends,whichevercomesfirst.AsyoufamiliarizeyourselfwithDigiPanorHamScopeoranyotherprogramthatyoudecideon,IrecommendtheCOEISASWH(clickoneverythinginsightandseewhathappens)approach.Thefeedpointimpedanceofaground-planeantennahavingaquarter-wavelengthradiatorisabout37ohmsiftheradialsarehorizontal;theimpedanceincreasesastheradialsdroop,reachingabout50ohmsatadroopangleof45°.MomandDaddidn’twantmetodrillholesthroughtheconcreteblocksforantennafeedlines.OnedayIdecidedtoseeifIcouldusemyhamrigasaVLFconverterbypluggingmyantenna(averticalontheroof,only17feethigh,meantforthe14-MHzhamradioband)intothemicrophonejackofthetransmitter,andthentransmittinganAMsignalinthe“spot”mode.AllocationsbyModeThelowest100kHzofthe6-meterband,from50.000MHzto50.100MHz,isreservedforCWoperationonly.WhenyouremovethecarrierandoneofthesidebandsfromanAMsignal,theremainingenergyhasaspectraldisplayresemblingthegraphofFig.Thatmeansyoumovethewavebackandforthintime,withoutchangingthefrequencydirectly.Youcangetenhancedperformanceifyouuseasmallantennatuner(alsocalledatransmatch)intendedforlow-powerHFhamradiouse.Forcompleteinformationonantennasafetymatters,youshouldconsultaprofessionalantennaengineeroracomprehensivereferencedevotedtoantennadesignandconstruction.Listencarefully!Inamassivepileup,somanystationsmightcalltheDXthatyoucan’tseparatethem.Conditionsarebadenoughintheantennafeedlineasitcomesintoyourreceiver;alittlemorenoisecomingfrominsidetheradioitselfwon’tlikelymatter.Theseinstallationscansaveyourlifeifyougetintoseriousdanger,aslongasyoustaywithinrangeofoneormore(andhavelearneditstone-squelchfrequencyinadvance).Figure7-4showsanexampleofatunedsmall-loopantenna.Itcandothiswitheitherarelayoranelectronicswitch.It’scalledimpulsenoise,anditcancomefromallkindsofhouseholdappliances,suchasvacuumcleaners,hairdryers,electricblankets,thermostats,andfluorescent-lightstarters.Manyrepeatershaveatimeoutfunction.ThenyoucancalculatetheantennapowergainusingtheformulaPowerGain(dB)=10log10(PERP/P)Inordertodefinepowergain,youmustdecideuponsomesortofreferenceantennaanddefineitspowergainas0dB,meaningnogainorlossatall,initsfavoreddirection(s).Frequencyappearsonthehorizontalscale,whichrunsinincrementsof1kHzperdivision.Infact,theHFbandperformedbetterthantheheavilyusedlonger-wavelengthfrequenciesdid,allowingreliablecontactsspanningthousandsofkilometersusingtransmitterswithlowormoderateoutputpower.SmallLoopAsmallloopantennahasacircumferenceoflessthan0.1wavelength(foreachturn)andcanfunctioneffectivelyforreceivingRFsignals.Ifyou’reaNovice,Tech,orTechPlusoperator,youcanuseanyofthedigitalmodesbetween28.000and28.300MHz,andSSBphonebetween28.300MHzand28.500MHz,keepingyourpoweroutputatorunder200wattsPEP.AnSSTVstationwithoutacomputerneedsatransceiverwithSSBcapability,ascanconverter,aTVset,andacamera.ThecomparativelyhighfirstIFandlowsecondIFgiveyouthe“bestofbothworlds.”ThedesignersofthesereceiverscascademultipleIFamplifiers(connectthemoneaftertheother).Butifyou’reanewham,consideryourselflucky.Buttakenote:IpulledintoparkinglotsandstoppedwhenIhadtodoanythingthatinvolvedfineadjustmentstotheradio,suchasRFpoweroutputorkeyerspeed.Forexample,12wpm=10bps,and30wpm=25bps.On1.25meters,Novicesarelimitedto25wattsPEPoutput,andon23centimeters,to5wattsPEPoutput.YoumightalsohearWWVHatthesametimeas,orinsteadof,WWV.Astormdoesn’thavetobeoverheadinordertoputyourradio,yourhome,andyourlifeatrisk.Theright-handdisplayshowstwoellipsesthatappearorientedhorizontallyandvertically,crossingeachotherasshown,whenyouhaveasignaltunedincorrectly,andassumingthatthesignalhastheproperamountoffrequencyshift.Theresultingdischargeproduceswidebandnoisethatsoundssimilartothenoisegeneratedbyelectricmotors,fluorescentlights,orotherappliances.Imagineaworkingcommunicationscircuitatafrequencyofafewkilohertzbetweentwospecificpointsontheearth’ssurface.Satellitelinkshavegrownincreasinglycommoninrecentyears.Hisworkappearsinseverallanguages.Youcanmoreeasilyfilterafixed-frequencysignalthanyoucanfilterasignalthatchangesinfrequency(asitdoesinadirect-conversionreceiver).Thebakingsheets,aswellasallpointsinthecordswheresplicesexist,aresetuponthickplasticshelves.At21MHz,a7-MHzdipoleformsaone-and-a-half-wavecenter-fedantenna.Inrecentyears,newmodeshaveemerged;youcanexpectmoretocome,eachofwhichoffersspecificadvantagesunderstrangeordifficultconditions.Whenandifhamsgetanynewbands,theARRLwillmakethemknownrightaway!CHAPTER5FixedHamStationsImaginethatyoujustgotyourGeneralClasslicenseandboughtsomeequipmentforastation.Thedestinationequipmentdetectsdiscrepanciesinreceiveddatabymeansofhandshaking,similartothemethodusedinAMTOR.Asparebedroomisanothergoodplaceforahamstation.It’salargeband,consideringitsplaceinthespectrum,occupyingfully12.5percentofthefrequencyspacebetweenDC(0Hz)and4.000MHz.Hamsareluckyindeedtohavethisband.QuadAquadantennaoperatesaccordingtothesameprinciplesastheYagi,exceptthatfull-wavelengthloopsreplacethehalf-wavelengthelements.Ifyou’relisteningonthisbandandyoutuneyourradiodownto15.000MHz,you’lloftenhearthetime-andfrequencystandardstationsWWVinColoradoand/orWWVHinHawaii.TipIfyou’rehavinganSSBcontactandyouwanttogainacertainmeasureofprivacy,switchtothesidebandthatgoesagainstconvention.•Anotchfilterisaband-rejectionfilterwithasharp,narrow,tunableresponse.Thegeneratorwouldfunction,butprobablynotatitsbestefficiency.Engineersexpressthislossindecibelsperunitoflength.6-6).That’soneofthebigadvantagesofcoax.Onetypeusesaleverorpairofleversthatyoupushtowardstherighttomakedots,andtowardthelefttomakedashes.Theexplosionofamultimegatonhydrogenbombataveryhighaltitude,whilenotcreatingadevastatingshockwaveorheatblastatthesurfaceoftheearth,couldgenerateadisruptiveEMPoveranentirenationoralargepartofanation.Itoccursasmultipletransmittedradiowavefrontsreflectfrommyriadtopographicalformations,suchascratersandmountainsonthemoon’ssurface,whoserelativedistancesconstantlychangebecauseofthe“wobbling.”Thereflectedwavesrecombineinconstantlyshiftingphasesatthereceivingantenna,sometimesreinforcingeachothertoproduceastrongersignal,andatothertimescancelingtoproduceadeepfade.Whenyouhaveareceiverwithasmallshapefactorandthengraphthesystemgainasafunctionoffrequency,yougetacurvethathasaflattopandsteepsides.Itformsatanaltitudeofabout50kilometers,andordinarilyexistsonlyonthedaylightsideoftheplanet.Butultimately,I’dliketoseeyoujointheAmateurRadiofraternity.Lookforthelowestpossiblevalue,expressedinmicrovoltsattheantennaterminals.25MetersTheshortwavebroadcastbandat11.600MHzto12.200MHzliesroughlyhalftheway,intermsoffrequencyandwavelength,betweenthehamradio30-meterand20-meterbands.Thenamecomesfromthefactthatthesignals,whichappearasbrightverticallines,movedownthescreenwiththepassageoftime,sothatthewholedisplaylookslikearealwaterfallifyouuseyourimagination.Eachofthesecurrentloopsactslikethecenterofahalf-waveantenna,sothewholelongwireineffectconstitutesasetoftwoormorehalf-waveelementsplacedend-to-end,witheachsectionphasedinoppositionrelativetotheadjacentsectionorsections.Whilemobileoperationcangiveyouplentyoffun,youshouldkeepinmindtheevergrowingpossibilitythatyourstateormunicipalitymightoutlawitsomedayiftheyhaven’talready.Ifyouoptforthebasement,you’llhavetofigureouthowtogetyourantennafeedlineorlinesintotheradioroom(whichhamscalltheshack,evenifit’sanelegantdedicatedbedroomorden).FIGURE6-8BasemountfortheHFportablewhipantenna.The“sweepingFM”remainsentirelyindependentoftheactualdatathatthesignalconveys.Intoday’sradios,DSPhasprettymuchtakenovertheIFfilteringjob.OnVHF,thetimeofdayrarelymakesadifference,butonHFitmattersalot.AcompanycalledPalomarEngineersoffersasetofproductsthatmighthelpyouinthiskindofsituation.Inputtuningreducesnoiseandprovidessomeselectivity.ThecarrierbeatsagainsttheLOinthemixer,producinganaudiotonethatalternatesbetweentwodifferentpitches.1-17,whynotlearnhowtoreadanddrawthemrightnow?Copyright©2015byMcGraw-HillEducation.Sendatareasonablespeed,suchas18to20WPM.Iftheelectricitywere“perfectlyclean,”you’dseeonlyonebrightverticaltraceattheextremeleftendofthedisplay.McGraw-HillEducationeBooksareavailableatspecialquantitydiscountstouseaspremiumsandsalespromotionsorforuseincorporatetrainingprograms.Ifnoonetellsyouthatthefrequencyisinuse,sendyourCQatthespeedyou’dliketogoinaQSO.Slowlytuneyourreceiverakilohertzortwoupanddownwhileleavingyourtransmitterfrequencyalone.IuseaprogramcalledDigiPanforPSK,anotherprogramcalledHamScopeforPSKandMFSK,andaprogramcalledMMTTYforRTTY.I’vetakenthreeextraprecautions,asidefrommakingsurethatIdon’toverloadthewalloutlet,toensurethatmy“tanglewiregarden”remainssafe.You’llalsoneedahigh-gaindirectionalantennaandasensitivereceiver.StandingWavesAlltransmissionlineshavesomeloss;theydonottransferenergywithperfectefficiency.Infrared,visiblelight,ultraviolet,Xrays,andgammarayscompriseEMfieldsthatalternateatmanytrillions(millionmillions)ofhertz.•Drawn-out,monologue-likeCQs.•Changingthetransmitterfrequencywhileputtingoutasignal.Waituntiltheoperatorstopstransmitting,andthenpushyourmicrophonebuttonandsendhisorhercallonce,followedby“thisis”andthenyourowncalltwice—withoutphoneticsthefirsttimeandwithphoneticsthesecondtime.This“bugaboo”(punintended)alsolowersthepower-handlingcapacityandincreasesthelineloss.Evenwirecommunicationscircuitssometimessufferilleffects.Inthatcase,youcanconstructanefficientantennaeveninthepresenceofsubstantiallossresistance.Coordinatenumbersindicateelevationanglesindegreesaboveorbelowtheplaneofthehorizon.Yourunthefeedlineinsidetheradialsleeve,feedingtheantenna“throughtheend,”asshowninFig.OpenDipoleAnopendipoleordoubletcomprisesahalf-wavelengthradiatorfedatthecenter,asshowninFig.Doyouwanttohaveaslow,easy,casualQSO(contact)withsomeone?Obviously,allwirelesstextmodesqualifyas“teleprintingoverradio,”includingRTTY,PSK,andMFSK.Many,ifnotmost,havereceivingcapabilitycontinuouslythroughouttheHFrange,andsomecanreceiveaslowasafewkilohertzandashighasseveralhundredmegahertz.RagChewingSometimesthecompetitiveaspectleaveseventhemosthard-bittencontestersandDXers,andtheywantnothingmorethantocarryonacasualconversationwithanotherham.Themaintroublewithladderlineisthat,ifitgetstwisted,theconductorspacingwillchange,andthewirescanshortoutbecausetheylackinsulation.TheversatilityandsignalrefiningcapabilitiesofagoodHFhamradiocomparefavorablywiththebestdedicatedallwavereceivers.FIGURE3-6TheHamScopeprogramworkinginBPSK31withaspectrumtuningaid.Figure3-13isagraphofasinglelineinanFSTVvideosignal,representing1/525ofaframe.58.Whenyouworkwithpower-supplydiodes,youmustpaycloseattentiontotwospecifications:theaverageforwardcurrent(Io)ratingandthepeakinversevoltage(PIV)rating.•AntennasforVHFandUHFhavemanageablesize(exceptperhapsforahalf-waveorJpoleantennaat6meters),soyoucancarrythemaroundwithouttrouble.Repeaters,evenlargeones,don’tconsumealotofelectricalenergy,sooff-gridsolutionsarepractical.Butgoupto10,12,oreven15meters,andyoushouldexpecttohearnothingotherthanreceiverhissand,ifyouliveinaplacewhereradio-noisyelectricalappliancesabound(asIdo),variousformsofhuman-maderoaring,buzzing,andpopping.TechTipPhasemodulationworksallrightforvoicecommunications,butsomeengineersthinkthatitdoesnotworkaswellasdirectFMforhigh-fidelityapplications,suchasmusicbroadcasting.Butoverallitaverages80meters:Infreespace,an80-meterwavehasafrequencyof3.7500MHz,preciselyinthemiddleoftheband.PreselectorApreselector,iftheradiohasone,providesabandpassresponsethatimprovestheS/Nratio,andreducesthelikelihoodofoverloadingbyastrongsignalthat’sfarremovedfromtheoperatingfrequency.IrecommendthemodelMFJ-16010orasimilarmodel.Atanygivenradiofrequency,thesolarfluxincreasesabruptlywhenasolarflareoccurs.IfalloftheRFfield’selectriclinesoffluxareperpendiculartotheaxisofthewaveguide,thewaveguideissaidtooperateinthetransverse-electric(TE)mode.Inthatcase,treatitasatwo-wireoutletuntilyoucangetaprofessionalelectriciantowireitupproperly.Inhigh-noiseorcrowdedbandconditions,narrowerIFbandwidthcanimprovethesensitivity.Caution:PoorlydesignedorcheapwattmetersgiveaccuratereadingsonlywhentheSWRis1:1witha50-ohmcoaxialfeedline(indicatingaperfectimpedancematchbetweenthelineandtheantenna).Onceagain,it’swww.arrl.orgTheARRLwillpublishinformationaboutanychangeinthelawconcerningallowablebandwidth,whenandifitoccurs.3-12B).Ifyouconnectanoninductiveresistorofthecorrectohmicvalueatthefarendofatransmissionline,wheretheantennawouldnormallygo,andthenyoutransmitasignalintotheline,notexceedingthepowerdissipationratingoftheresistor,thevoltage-to-currentratiowillremainconstantallalongtheline.NewYork:McGraw-Hill,1993.Whenanantennaradiatormeasuresacertainheightorlengthatagivenfrequency,andifyouconstructitoflow-losswireormetaltubing,youcangetitsradiationresistancetoexceed1000ohms.Gibilisco,Stan,TeachYourselfElectricityandElectronics,5thed.Foranyantennaoperatingataspecificfrequency,thereexistsauniqueresistanceRR,inohms,forwhichyoucanmakeatransmitter“think”thatanRCorRLcircuitis,infact,thatantenna.OtherFeaturesAnothernotablefeatureofMFSK16isthewaythesignalmodulationkeepsgoingintransmitmode,evenwhenyouaren’ttypinganythingonthekeyboard.IfanFMsignalhasabandwidthgreaterthanthatofastandardAMsignalwiththesamemodulatingwaveform,thenit’scalledwidebandFMorWBFM.FIGURE7-12Ahelicalantennawithaflatreflector.Ifyouneedtoincreasethemicrophonegain,usethetransmittercontrol;don’tshout.Ideally,eachoutletshoulddoroughlythesameamountofwork.SharingwithOtherServicesAmateurRadiooperatorsenjoyfullprivilegesonthisband,notlegallyhavingtoyieldtoanybodyelse.Andthatperformancecan,Ihaveheard,bespectacularindeed.Usingyourmouse,placethepointerontheupperborderoftheblackregionanddragthatborderupwarduntilthewhiteregionwiththedistractingtextvanishes.Thecircuitsetstheclippingthresholdaccordingtothestrengthoftheincomingsignal.TheratioofPEPtotheaveragepowerdependsontheemissionmode.FIGURE6-13ModifiedandenhancedbatteryterminaltofacilitateeasyinsertionandremovaloftheDCcablewiresandtoensuregoodelectricalcontacttocarrythecurrentthatthetransceiverdemandswhen“key-down.”•You’llhaveaneasiertimemakingcontactsrunningQROthanyouwillhaveifyourunQRP,assumingallotherfactorsremainconstant.•GeneralClassoperatorscanusetherangesfrom7.025MHzto7.125MHzfordigitaloperation,and7.175MHzto7.300MHzforphoneandimaging.Asmallloopexhibitsasharp,deepnullalongitsaxis(perpendiculartotheplaneinwhichtheconductorlies).Thespindirectioniscalledthesenseofpolarization.Insuchfast-pacedoperatingenvironments,simplymakingthecontactistheonlythingthatmatters,anyway!OperatinginSSBOntheHFbands,singlesideband(SSB)isthemostcommonvoicemode.Ifanyoneisusing60metersyou’llprobablyhearsignalstheretoo.Televisiontakestwoforms:analogfastscanandslowscan.Alternatively,anincreaseininstantaneousdatalevelmightslowdowntherateatwhichthepulsesemerge(negativePIM).40MetersThe40-meterbandspans7.000MHzto7.300MHz.Infreespace,a40-meter-longwavehasafrequencyof7.500MHz,slightlyabovethehamband,whosecenterfrequencyactuallyliesjustunder42meters.InhamFAXpractice,120or240linesperminute(twoorfourlinespersecond)arescanned.Thatcontestinvolvesportableoperationusingemergencystationsandpowersources.It’saHamScopespectrum-modedisplayofaW1AWbulletininBPSK31,tunedtoafundamentalaudiofrequencyof689Hzafterpassingthrougha250-Hz-wideCWfilterinmyreceiver.Hamequipmentusingvacuumtubesneeds100voltsto3000voltsDC.Falsesignalscausedbyfilterringing,atmosphericnoise,orignitionnoisearegenerallyignored,becausetheyrarelyproducesufficientaveragebitvoltage.Tocontactarepresentative,pleasevisittheContactUspageatwww.mhprofessional.com.Buttheyshouldnotbetooclosetogether,orthedesiredsignalswillgetcanceledalongwiththenoise.6-3).InPAMandPWM,youalwaystransmitthepulsesatthesametimeinterval,knownasthesamplinginterval.PacketRadioApacketisablockofdigitaldatasentfromacomputeratasourcestationtoanothercomputeratadestinationstation.Oneguycalledtheplan“invectivelicensing.”Iguesspeoplegetunhappywhentheirgovernmenttakesthingsawayfromthem.9.Rememberthatrepeatersexistnotonlyforconvenience,butalso(andmoreimportantly)toserveinemergencies.Signalsappearasbrightverticallines.RadioteletypeRadioteletype(abbreviatedRTTYandsometimespronounced“ritty”)involvesthewirelessexchangeofprintedorscreen-displayedtextmatter.Perhapsbetterstated,thesuballocationsrestrictusagetocertainmodes.6.IfthefirstIFsignalpassesstraightintothedetector(signaldemodulator),youhaveasingle-conversionreceiver.Asuddennoiseburstinanon/offkeyedsignalcan“confuse”areceiverintofalselyreadingaspaceasamarkwhenon/offkeyingisused,butwhenthespaceispositivelyrepresentedbyitsownsignal,thistypeoferrorhappensfarlessoften.Whenyoudouseit,makesurethatnothunderstormsexistanywherenearby.That

includesyou,mostlikely.I’veencounteredthisconditiononwinterafternoonsandevenings.You’llfindinformationaboutthistrend,aseventsunfold,attheARRLwebsite.Atoneof1500Hzcorrespondstoblack;2300Hzgiveswhite.Thelinesrunhorizontallyacrossthescreen,whichhasahorizontalto-verticaldimensionalratio,oraspectratio,of4:3.You’llrarelyseethisresolutionlevelofVHF/UHF,butsomeradioshaveitallthewayfromthelowestcoveragefrequencytothetop.Auroralpropagationseldomoccursinthetropicsorsubtropics,wheneitherthetransmittingstationorthereceivingstationislocatedatalatitudelessthan35°northorsouthoftheequator.Thatratioappearstobe15dBinthiscase.Youmightconsidermoonbounceatechnicalexceptiontothe20,000kilometerpathlimitbecausewhenyoumakeacontactinthatmode,thesignalmusttravel800,000kilometerstothemoonandbackregardlessofthelocationoftheotherstation!ButmoonbounceandDXingareentirelydifferentwhenitcomestooperatingpracticesandattitudes.FacsimileRadiohamscansendfacsimile(FAX)imagesbymeansofnarrowbandtransmissions,inamannerverymuchlikethewayitworksovertelephonechannels.Whenpowergainoccursinthedirectionoppositetheparasiticelement,youcallthatelementareflector.Table4-2breaksdownthe80-and-75-meterbandaccordingtolicenseclasssuballocationsandmodeusagerestrictions.FIGURE5-7Afull-wave,voltage-doublerpowersupply.Generally,suchantennasmustmeasureatleast1/4electricalwavelengthifgoodresultsaretobeobtained,althoughsometransmatchescanprovideanimpedancematchwithshorterwires.•Shapefactor—Inareceiver,theshapefactorexpresseshowclosetheIFbandpassfiltercomestohavingarectangularresponse.Ifyouget0again,repeatsteps8and9withalltheACvoltagefunctionsthatthemeterhas,goingdownuntilyou’vetestedatthelowestACvoltagesetting.APBBScanfunctionevenwhenthedestinationoperatorsarenotphysicallypresenttolookaftertheirstations.TipOnallthehambands,CWemissionisallowedfromtoptobottom.McGraw-HillEducationhasnoresponsibilityforthecontentofanyinformationaccessedthroughthework.Ifyousendeverythingat18WPMonceandtheotherstationgetsit,you’llgetatleastasmanycontactsovertimeasyouwouldgetifyousenteverythingat36WPMtwice.Finally,youneverhavetoworryaboutRFexposurewithtrueQRPof5wattsorless.FIGURE1-6Theionosphereappearsabovetheearth’ssurfaceatvariousaltitudesinlayerscalledD,E,F1,andF2.•AnaudiopassbandfiltercanenhancereceptionaboveandbeyondtheperformanceobtainablewithIFfilteringalone.TABLE4-5SuballocationsintheUnitedStatesforthe15-meterband(21.000MHzto21.450MHz)asofMarch2012.Hi-fistereobroadcastinginthebandfrom88MHzto108MHzprovidesagoodexample.•WithQRO,you’llhaveabetterchanceofmaintainingacontactonceyou’vemadeit;you’llbelesspronetohavingQSOscutshortbecauseofinterferenceorfading.Suchafiltermustbedesignedforafixedfrequencyifyouexpectittoworkwell.Whenviewedthroughatelescopeequippedwiththeappropriatefilters,asolarflareappearsasabrightfleckorstreameronthesolardisk,thousandsofkilometersacrossandthousandsofkilometershigh.Itusedasingle-conversion,superhetdesignofthesortshownbackinChap.InordertoefficientlypropagateRFenergy,arectangularwaveguidemusthavesidesmeasuringatleast0.5wavelength,andpreferablymorethan0.7wavelength.Thereceiverisprogrammedtofollowthetransmitterfrequencyfrominstanttoinstant.Between7.125MHzand7.300MHz,phoneandimageemissionsareallowed.Eitherofthesedesignsgivesyouatwo-elementYagi.It’sdeterminedbymeasuringthepassbandwidthfortwoattenuationlevelssuchas−6dBand−60dB,andthendividingthelatternumberbytheformer.Becausespringandsummeroffersdayswithmoresunlittimethandarktime,thebandsat14MHzandupwillmorelikelyyieldgoodDXduringthosemonths.Engineersandscientiststhoughtthathigherfrequencieswouldn’tprovidegoodperformanceinpractice,sotheyallbutignoredthemasan“electromagneticwasteland.”Thevastregionoftheradiospectrumcomprisingwavelengthsof“200metersanddown,”correspondingtofrequenciesof1.5MHzandabove,remainedsubjecttothewhimsandingenuityofAmateurRadiooperatorsandexperimenters,whobecameknownashamsbecauseoftheirflamboyanceandsupposedlyunprofessionalcharacter.Ofcourse,ifyouliveinacondooranapartment,orifyouliveinapartofthecountrywherebasementsdon’twork(SouthFlorida,forexample),youdon’thavethisoption.HowDoTheyLook?Bruteforcemakestheworldsmall.SearchingforthisphenomenonmightmakeyoufeelalittlelikeanastronomerworkingonSETI(theSearchforExtraterrestrialIntelligence).Ilearnedhowto“tweak”themaintuningdialtogetreasonablebandspreadscaleaccuracybytakingadvantageoftheNationalBureauofStandards(nowcalledtheNationalInstituteofStandardsandTechnology)time-and-frequencystandardbroadcasts.Thisphenomenontakesplacebecauseairmolecules,dustgrains,andwaterdropletsscattersomeoftheEMfield,justastheyscatterlightrays.Youcanseethat,whenyoucombinetheirspectrumspace,theytakeupasignificantpartoftheHFradiozone.That’ssplatter!FIGURE3-10AtA,anamplitude-versus-timegraphofafullymodulatedSSBsignalwithasine-waveinputatthemicrophone,freeofpeakclipping.ContentsIntroduction1HobbyRadio:ATechnicalOverviewShortwaveRadioAmateur(Ham)RadioCitizensBand(CB)RadioElectromagneticFieldsRadioWavePropagationMorseCodeandRadioteletypeVoicesonWavesReceiverFundamentalsPredetectorStagesDetectorsExoticCommunicationsMethods2ShortwaveandAllwaveListeningHowIGotintoSWLShortwaveBroadcastBandsSunspotsandShortwaveRadioLongwaveRadioDirtyElectricityWhichRadio’sforYou?Arandomwire,ofindeterminatelength(butaslongaspossible),strungupoutdoorsashighabovethegroundasyoucanplaceit;or2.AllocationsbyLicenseClassIfyouhaveaGeneral,Advanced,orExtraClasslicense,youcanoperateoverthewhole12-meterband.Youcangetawaywitharathersmallantennaon17meters.WhatIsMFSK?Thecoordinateoriginrepresents25dBdown(−25dB)withrespecttothemainlobe,andalsoshowsthelocationoftheantenna.Inthissituation,youcandefinetwoseparatef/sratios:onebycomparingthesignallevelbetweennorthandeast(theright-handf/sratio),andtheotherbycomparingthesignallevelbetweennorthandwest(theleft-handf/sratio).FIGURE5-4AbroadbandRFpoweramplifier,capableofproducingafewwattsofoutput.Thesmallopencirclerepresentsthegroundrod;heavydashedlinesrepresentquarter-wavelengthburiedradials.ErrorcorrectionisincorporatedintheformofFEC,similartothemethodusedinMFSK.Such“holes”areusuallyassociatedwiththundershowers.What’sPEP?IlovedhamradioandIwantedallofit!ButsomehamsgotfuriouswhentheysawnearlyhalfoftheirprivilegesonSSBand/orCWtakenaway.Silver,H.You’llseeafewcharactersarriveallatonceonthescreen,followedbyapause,followedbyafewmorecharactersallatonce,andthenanotherpause,andsoon.Nogeneratoroperatesat100-percentefficiency,butagoodonecancomefairlyclosetothatideal.Somecontestsareorganizedbyregionorlocality;othersinvolvespecialties,suchasCWorRTTYor160metersonly.Suchanantennaexhibitsasharpnull(zoneofminimumsensitivity)alongtheloopaxis.ThisstationdoublesasthemobileinstallationIcouldalsousewhilecamping,orforanemergencysituation,orfortheannualARRLFieldDaycontest,butIcouldn’twalkaroundwithitandoperateitatthesametime.Thefulllegallimitisallowed,andthere’snosharing,either!CharacteristicsThisbandbehaveslikethe11-metershortwavebroadcastband.Themostefficientdish,especiallyattheshortestwavelengths,comprisesaparaboloidalreflector,sonamedbecauseit’sasectionofaparaboloid(thethree-dimensionalfigurethatyougetwhenyourotateaparabolaarounditsaxis).Therapidpulsations(solidcurves)occurattheRFcarrierfrequency;theslowerfluctuation(dashedcurve)portraysthemodulatingdata.Troposphericbendingoccursbecausetheindexofrefractionofair,withrespecttoradiowaves,decreaseswithaltitude.Wave-propagationcharacteristicsarediscussed,comparingthevariousbandsandofferingadviceastothosebandsbestsuitedforuseatdifferenttimesoftheday,year,andsunspotcycle.Ifdoneproperly,clippingcanimprovetheintelligibilityofanSSBsignalinthesamewayascompressiondoes,butclippinggeneratessplatterasamatterofcourse!Wheneverspeechclippingisused,therefore,ahigh-quality,3-kHz-widebandpassfiltermustfollowtheclippingcircuittokeepthesplatterofftheair.Thetransmittersequencecontainsnumerousdwellfrequencies,sothesignalenergygetsdilutedtotheextentthat,ifsomeonetunestoanyparticularfrequencyinthesequence,theywon’tnoticethesignal.Acoronaissometimesobservedbetweentheplatesofcapacitorshandlinglargevoltages.Whenyouquantifythem,youfindthattheyexhibitaninverserelation:asoneincreases,theotherdecreases.Ifthere’snotmuchinterference,fading,ornoise,thenthesignalcruisesalongatmaximumspeedbecausethetransmittingstationmustsendeachgroupofthreecharactersonlyonce.Insomecasestheimprovementcanexceed20dB,meaningthatthesignalpowerstaysthesame,whiletheoffendingenergygets100timesweaker!LoopstickForreceivingatfrequenciesuptoapproximately20MHz,aloopstickantennacanfunctioninplaceofasmallloop.Eachsucceedingdirectorisslightlyshorterthanitspredecessor.However,somecommerciallymanufacturedautomaticantennatunershavesensitiveinternalelectronicsthatcansufferdestructionfromthestrongEMfieldproducedbyanearbylightningstrike.Ifyourhomehasanold-fashionedup-and-downslidingwindowandyoucangetyourradionexttoit,youcanrunfeedlinesandotherwiresthroughtheopeningusingtheschemeshowninFig.KeyclickscanmessupaCWtransmitter’ssignalbigtime.Nowadays,thecommonlyusedcodeistheInternationalMorseCodeorContinentalCode.Intheory,arectangularresponseischaracterizedbyzeroattenuationinsidethepassbandandinfiniteattenuationoutsidethepassband.6-10,tothetopofthetransceiverwith“stickypads,”makingsurenottoobscurethespeakeroranyoftheventilationopenings.Thecarrierpulsationsgetsmoothedoutastheoutputpassesthroughacapacitorlargeenoughtoholdthechargeforonecarriercurrentcycle,butnotsolargethatitdampensorobliteratesthefluctuationsinthemodulatingsignal.Thiscuriosityconstitutespartofagoodoperator’smentality!You’llalsowanttotelltheoperatorontheotherendhowwellhisorherstationisdoingatyourend.TheARRLmaintainsawebsiteatwww.arrl.org.Ifthiscurrentis4amps,forexample,therectifierdiodesshouldberatedatIo=6ampsormore.Youcanmakelotsofcontactsifyoucangetthatdipoleoutdoorsandhighenoughsothatatallpersonwon’trunintoit.Themodulationmethodcanbeeitherpositiveornegative.Thatway,eventhoughahunterstationwillprobablymakefewercontactsthanapreystation,thehuntercanmakeupforthatshortfallinpartbygettingmoremultipliers.Thedarkestpartofthespotliesat,ornear,thecenter,aregioncalledtheumbra.Thatthinghasworkedflawlesslyformorethanadecade.AnOldTimerRemembersTheshortwavebroadcaststationscangetannoyingintheupper100kHzof40meters.7-8A.ThefirsttypeofLFandVLFlisteningantenna,theoutdoorlongwire,prettymuchexplainsitselfintermsofdesign.Youshoulddothesamewithyourfixedstationequipment!1.•ThefrontendservesasthefirstRFamplifier,andmayincludeabandpassfilterbetweentheamplifierandtheantenna.The2800-MHzsolarfluxcorrelateswiththesunspotcycle.TipHumanmadenoisefrommiscreanthomeappliancesknowsnolimitonanyhamband,and12metersisnoexception.Foradditionalgain,severalhalf-wavedipolescanbefedinphaseandplacedalongacommonaxiswithasingle,elongatedreflector,formingacollinearcorner-reflectorarray.Shamieh,CathleenandMcComb,Gordon,ElectronicsforDummies,2nded.Ignoretheshiftkeyexceptwhenyouabsolutelymustuseittosendaparticularcharacter.•DualVFOsallowthereceiverandtransmitterfrequenciestobedeterminedindependentlywithinagivenband,or,insomeunits,incrossbandmode(transmitandreceivefrequenciesindifferentamateurbands).WouldyouwanttohearmesendthefollowingextremeCQ?BecauseoftheexplosioninCBuseduringthe1970s,theFederalCommunicationsCommission(FCC)increasedthenumberofchannelsto40intheUnitedStates,andsinglesideband(SSB)voicemodewasintroducedtoconservespectrumspaceandimprovecommunicationsreliability.Acommonmethodofgeneratingspread-spectrumsignalsinvolvessocalledfrequencyhopping.Theradiusofthehelixshouldbeapproximately0.17wavelengthatthecenteroftheintendedoperating-frequencyrange.AnHFradiocommunicationsreceiver,especiallyonethatofferscontinuouscoverageofthespectruminthatgeneralrange,issometimescalledashortwavereceiver.Youcanofcourseusegoodjudgment,butthatwillonlytakeyousofarthesedays.Figure3-10Ashowsanamplitude-versus-timegraphofafully,butproperly,modulatedSSBsignalwithasine-waveaudioinput.Theconductorsaremoldeddiametricallyoppositeeachotherinalong,flexiblecylinderofpolyethylene.Thesensitivityismaximumoffthesidesofthecoil,andasharpnulloccursofftheends.Whenelectronsacceleratebackandforthatadefinedandconstantpace,theygenerateanalternatingmagneticfieldatthesamerate,orfrequency,asthatoftheirmotion.You’llalsohavetoknowthesplitfortherepeaterthatyouwanttouse.(ItcantransmitonlywithintheAmateurRadiobandsthatexistedintheUnitedStatesatthetimeofitsmanufacturearound2001.)MostothergoodHFham“rigs”candothesamething.Analternatingmagneticfieldgivesrisetoanalternatingelectricfield,whichinturnspawnsanotheralternatingmagneticfield,andthenanotherelectricfield,andsoonindefinitely.•You’llfindrepeateractivityon2metersand70centimetersexceptinthemostremotelocations.Thenyoucansendtheotherstation’scallfollowedbyyourown,andfinallythelettersSandKruntogether(di-di-di-DAH-di-DAH).This“resistancemultiplication”propertymakesthefoldeddipoleidealwhenusingparallelwiretransmissionlines.Imakethatquerybysending“QRL?”followedbyapauseandthen“DEW1GV.”Ifthefrequencyisoccupied,you’llprobablyhearsomebodysendthesingleletterC(meaning“Yes”).Byadjustingthenotchfrequency,youcannulloutinterferingheterodynes(carriersthatproduceaudiotoneswithaproductdetector).Astandardfaxhasaprintersimilartoaphotocopierorlaserprinter.AnOldTimer’sTrickYoucanmountaCWkeyerpaddleonaboardsothatyoucanuseitonanysurface,eveninyourlap,whileworkingportable.Normally,thecommunicationsrangeonthe11-meterbandrarelyexceeds30kilometers.SoIhadtorunthefeedlinearoundthewindinghallwaythatledintotheplace,andoutintothefurnaceroom,andupthroughtheoutsidewallofthehousejustabovegroundlevel.Thesquelchopensonlyinthepresenceofsignalsmodulatedbyanaudiotone,orsequenceoftones,havingthepropercharacteristics.•Mostvehicles’electricalsystemscansupportradiosthatconsumeuptoabout500watts,whichtranslatestoabout200wattsRFoutput.Youcanchoosethesumsignalorthedifferencesignalforsubsequentamplification.TipNeverbehavelikeaCitizensBandoperator(CBer)onahamradiorepeater!Forexample,ifyouwanttobreakintoaQSO,don’tsay“BreakBreakBreak.”Simplysayyourcallsign.Thenonlinearityfacilitates(and,infact,encourages)theheterodyningthat’snecessarytoobtainsumanddifferencefrequencysignalsthatresultindataoutput.PointyourWebbrowsertoBesidestheRigBlasterPro(whichtheystilloffer),theyhavesimplerdigitalinterfaceunitsforhamswithlimitedobjectives.Don’ttrytoadjustyourradio’smicrocomputercontrolled,menu-drivenfunctionswhiledrivingavehicle.AdvantagesofVHFandUHFPortableForlightor“walk-around”portableoperation,VHFandUHFpredominate.InaradiowithVOXcapability,ananti-VOXsystemusesnegativefeedbacktokeeptheVOXfromkickinginwhenyourmicrophonepicksupaudiofromyourreceiver’sspeaker.CoronaeWhenthevoltageonanelectricalconductor(suchasanantennaorhighvoltagetransmissionline)exceedsacertainlevel,theairaroundtheconductorbeginstoionize.Coordinatenumbersindicatecompassbearinganglesindegrees.Onawinternightwhensolaractivityishighbutnotoutofcontrol,the40meterbandcanprovideyouwithhoursoffun,evenifyoucanmanageonlyalowdipoleasanantenna.TheNISTbroadcaststimeandfrequencystandardsignalsintheUnitedStatesfromtwolocations,oneinColorado(WWV)andtheotherinHawaii(WWVH).Don’tletsuchgarbagegoovertheairwithyourcallsignonit!FIGURE3-7Harmonicdistortioncommonlyoccursintheaudiostagesofradiosandcomputers.Getapieceoflumberthathasthesamethicknessasthedepressionatthebaseofyourwindowsash.Thatway,theDXwillmorelikelyhearyouwhenyoucallalongwithotherstationssimultaneously.ACWreceiverworkswellwithanIFbandwidthof500Hz,whileforSSB,anIFbandwidthof2.7kHzistypical.•Weightcontrols—High-endradioswithbuilt-inelectronickeyerssometimeshaveCWweightcontrolstocompensateforthevaryingtastesofreceivingoperators,andfortheeffectsofhighspeedonthesignalenvelope.WhenIfirstputthiscircuittogether,Ididn’tknowhowwellitwouldwork.•AntennasformobileHFoperation,whilelessefficientthanthoseforVHFoperation,cangiveyouplentyofcontactseveniftheywasteconsiderableRFpowerintheprocess.Here’showIdoit:CQ,CQ,CQ,thisisW1GV.IdeployeditontheHFbandsfromtheguesthouseattheStargazerRanchinMeeteetse,Wyoming,andenjoyedgreatDXingwith50wattsoutputon10,12,15,17,and20meters.Inthiscable,thecenterconductorcanmovearoundsomewhat,butthepolyethylenekeepsitfromshortingouttotheshield.Bewareofsuddenthundershowersthatcanexposeyouandyourequipmenttodangerfrominducedcurrentsorcatastrophicvoltagesfromlightningstrikesonorneartheantenna.Thesensitivitydependsonthegainofthefrontend(theamplifierthatthesignalentersfromtheantenna).However,alowIFallowsforsuperiorselectivity.Onaccountofthesesevererestrictions,mostLowFERsuseMorsecodeordigitalmodesforcommunicationinordertoensurethatpeoplelisteningforthemgettotakeadvantageofthebestpossiblesignal-to-noise(S/N)ratio.DuctingtakesplacewhenEMwavesget“trapped”withinalayerofcool,denseairbetweentwolayersofwarmerair,aphenomenoncalledtheducteffect.Warning!Don’teventhinkabouttransmittingsignalsontheAmateurRadiofrequencieswithoutgettingalicensefirst.Inthissystem,knownasslopedetection,anonlinearrelationshipexistsbetweentheinstantaneousdeviationandtheinstantaneousoutputamplitudebecausetheskirtofthepassbanddoesnotproduceastraightlineinagraphofamplitudeversusfrequency.It’salotlikeelectronicmail(e-mail)inthatrespect.•Abuilt-inCWkeyerletsyouconnectakeypaddle(suchastheVibroplexVibrokeyer,myall-timefavorite!)totheradiodirectly,withouthavingtopurchaseanoutboardelectronickeyerbox.Duringtimesoflacklustersolaractivity,thisbandoftengoescompletelydead,withtheskipzoneineffect“expandingtoinfinity”24hoursaday.TipAtthetimeofthiswriting,IfoundanexcellentwebsitethatdelvesintotechnicaldetailaboutPSK.Nowadays,digitalradiosoffernear-perfectfrequencycalibration,andyoucangetaclockthatautomaticallysynchronizesitselftoanothertime-and-frequencystandardstation,WWVLat60kHz,orelsesimplylookatyourInternet-connectedcomputer’sclock!Soyouprobablywon’tneedtousethesestationstocalibrateanything.You’llfinddetailsaboutspecificfrequencyprivilegesforthevariouslicenseclassesasyoureadtheband-by-bandbreakdowninformationinthischapter.Thatway,iftheprogramdoesn’twork,youcan(inadditiontodeletingtheprogramitself)takeyourOSbacktothestateitwasinbeforeyoudownloadedtheprogram.Figure113showsanexampleofthisscheme,knownasreactancemodulation.Becausehamswhouse160metershavegainedalong-standingreputationforcourtesyandrespecttowardsotheroperators,thispartofthespectrumgoesbythenickname“thegentlemen’sband.”Forthemostpartthatremainstrue,butwemightdowelltorememberthatsomefemalehamsexist!Maybeweshouldcallit“thegood-mannersband.”80MetersThe80-meterbandextendsfrom3.500MHzto4.000MHz.Sometimestheupperhalfofthisbandiscalled75meters.TipYoucanfinddetailedinformationaboutthevariousclassesofRFpoweramplifiersinmybookTeachYourselfElectricityandElectronics.OnSSB,youmighthearsnidecommentsorinanequestions,suchas“Screwoff!”or“Who’stheDX?”TipResistthetemptationtoanswercommentsandquestionsfromlids.Acircularlyorellipticallypolarizedwavecanturneitherclockwiseorcounterclockwiseasyouseethewavefrontscometowardyou.Theshieldisconnectedtoanelectricalground.You’llgetapileupthatwayifyouchooseabusyband.Sonomatterhowmodestyourstationis,trythisband!AllocationsbyModeOn40meters,youmayuseonlydigitalmodesonthelowermost125kHz(7.000MHzto7.125MHz),includingCW,RTTY,PSK,MFSK,datatransmission,andothermoreexoticdigitalmodes.Figure6-14showsthegeneralcontourofthisantenna,whichemploysamechanicaldevicetotunetheantennatoresonanceanywherefrom40meters(7MHz)upthrough70centimeters(450MHz).Ifyoudothat,you’llhavetoshortentheelementsslightlytomakeupfortheloadingeffectsthatthespheresintroduce.ThestrongestgalacticnoisecomesfromthedirectionoftheconstellationSagittarius(“TheArcher”)becausethispartoftheskyliesonalinebetweenourSolarSystemandthecenterofthegalaxy.Ifthereceiver“sees”acharacterthatdoesnotadheretothe4:3mark-to-spaceratiorule,thenitcanconcludethatanerrorhasoccurred.AnOldTimerRemembersWaybackinthe1970swhenIattendedcollegeinMinneapolis,Minnesotaandvisitedmyparents’housedowninRochestereveryotherweekendorso,Ihadagreattransmitterandreceiverforhamradio.Radiohamscommunicatefromcars,trucks,trains,boats,aircraft,motorcycles,bicycles,andevenonfoot.ItworksgreatforcrackingpileupsifIsenditonceat15to18WPM.Thesefiltersrivaltoday’sdigitalsignalprocessing(DSP)forperformance.Ladderlinehaslowlossandhighpower-handlingcapacity,eveninthepresenceofsignificantmismatchesbetweenthelineandtheantenna.FIGURE1-14Time-domaingraphsofvariousmodesofpulsemodulation.Igluedthestripsdowntherewithepoxyresin.2-12B,awaveisshownalongwithitssecond,third,andfourthharmonics,astheentire“signal”wouldappearonaspectrummonitor.Janskyconductedexperimentstoinvestigateandquantifytheearth’satmosphericnoiseatawavelengthquiteclosetothatofthehamradio21-MHzband.Thisphenomenonisespeciallylikelytohappenduringsnowshowersorstorms;thenthenoiseiscalledsnowstatic.HerearesomereasonstorunQROmobile:•You’llhaveaneasiertimemakingcontactsrunningQROthanyouwillhaveifyourunQRP.Inpractice,linelossespreventtheSWRfrombecomingtrulyinfinite,butitcanreachvaluesof20:1ormoreinareal-worldtransmissionlinewhenashortoropencircuit,orapurereactance(capacitanceorinductance),takestheplaceoftheload.Laterprojectswiththatkitincludedsubstitutionofadifferentantennacoil,onethatlookedsmallerthantheoriginal.Ithasexistedforoverhalfacentury,andyoucanstillbuyonetoday.WhenIsawhowmuchenergyexistsattheharmonicfrequenciesinandaroundmyhouse,myastonishmentknewnobounds.Thebestcommerciallymanufacturedradioscanrunyouupwardsofathousanddollars;thecheapestkitsor“miniradios”mightcostyouonly$30or$40.Locationsareapproximateine-readers,andyoumayneedtopagedownoneormoretimesafterclickingalinktogettotheindexedmaterial.WhenIwasfirstlicensedatage12,myrigwentinthefamilyfalloutshelter,whichmyparentshadbuiltaftertheCubanmissilecrisis.Suchadisplayisoccasionallyseenatthetipofthemastofasailingship.Amateurradiooperatorshaveanexpressionforit:“RFintheshack.”Youcanminimizewoesofthissortbycarefullycuttingtheantennaradiatortoahalfwavelengthatthefundamentalfrequency,andbyusingtheantennaonlyat(orextremelynear)thefundamentalfrequencyoroneofitsharmonics.Honda,Yamaha,andothermanufacturersofferseveralportablegeneratormodels,someofwhicharealittlesmallerthanmine,andsomeofwhicharequitealotbigger.Therelativeintensityateachfrequencyappearsasacolor.Moreoften,6-meterionosphericpropagationtakesplaceviatheElayer,whichtendstoionizein“clouds”atanaltitudeofaround80kilometersduringperiodsofsunspotmaxima.Keepyourcallshort.Ifyoucangetthatdipoleupatleast7meters,youcanexpectdecentresults.Thesmallertheresult,thebetter.Ifyoudon’t,thenyouknowthatsomeACvoltageexistsbetweenthetwopoints,soyouroutletdoesnothaveagoodground.Thisso-calledionospherehasseveralzonesofionization(regionswheretheatmosphere’satomshaveanelectriccharge)thatoccuratfairlyconstant,predictablealtitudes,asshowninFig.Precipitationstaticcanmakeradioreceptiondifficult,especiallyatlowfrequencies(longwavelengths).RectifierDiodesRectifierdiodesareavailableinvarioussizes,intendedfordifferentpurposes.10.That’sbecausemostoperatorsinthosemodesusesimplecomputerprogramsandinterfacesthatautomaticallysendonthefrequencytowhichthey’retuned,andlackthecapabilitytosearchforanybodywhomightcallthemonsomeotherfrequency.Keepyourtransmissionsshortandtothepoint.Youshould,inanycase,haveagooddisplaysothatyoudon’tgeteyestrainfromlookingatallthatdecodedtext!Inordertoreceivesignalsonanynon-CWdigitalmode,youneedtoconnecttheaudiooutputofyourradio(fromtheheadsetjack,inmostcases)tothe“linein”jackonyourcomputer.Acapacitor,inconjunctionwiththecoil,formsatunedcircuit.Asthewavelengthgrowsshorter,antennasingeneralgrowsmallerforagivenamountofgain.Fromworsttobest:•Readabilitynumbersgofrom1to5.Nowsupposethatyouincreasethefrequencygraduallyuntilcommunicationfails.Ifyougetseriousabouthobbyradio,andespeciallyAmateurRadio,you’llwanttogetcomfortablewiththesediagrams.Lookforthelatestedition.Ifyouhaven’theardorreadaboutPEP,here’saquickdefinition:It’sthemaximuminstantaneousRFsignalpowerthatyourtransmitterputsout.Onmorethanoneoccasion,Iswitchedmyradiototheband,listenedforabouttwominutes,gaveupinfavorofeither80metersor20meters,orelseleftthehamshackanddidsomethingelse.•Deliberatelyinterferingwithotherhams’QSOs.•Failingtoheedinstructionsforcallingastationwhenitsoperatorgivesspecificinstructionsforcalling.PortablePowerOptionsAswithmobile,youcangetaradiothatrunseitherQROorQRPtoworkportable.Thisglowcommonlyoccursattheendsofaradio-broadcastorcommunicationstransmittingantennaelementwhenthetransmitterhashighpoweroutput.Don’trunitoverorunderelectricalpowerlines.Ifyou’reusingananalogmeter,tweakthe“0ΩADJ”knobsothatthemeterindicates0.TheabbreviationPTTstandsforpushtotalk.Speedsareexpressedinwordsperminute(wpm).Asmallscreendisplaysthesignalsasverticalpipsalongahorizontalaxis.Thelowerpartofthescreenshouldbeblackwithagraduatedscaleatthetop,showingthenumerals1000,2000,3000,andsoon.That’sSomeAntenna!SomecommerciallymanufacturedYagishaveupwardsofadozenelements.Reversethetestleads.110.InsoutheasternMinnesotawhereIlived,lateJunewasprimetimeforthunderstormsandtornadoes.Visitahamradioconventionoryourlocalhamradiocluband“picksomebrains”forspecificinterfacerecommendations.Normally,thepulsewidthincreasesastheinstantaneousmodulatingsignallevelincreases(positivePWM).UnitsdesignedforVHFandUHFmightcoveroneband,suchas2meters,ortwobands,suchas2metersand70centimeters.Theseunitslooksomethinglikethetoy“walkie-talkies”thatchildrenusetocommunicateovershortdistances.Horn,Delton,HowtoTestAlmostEverythingElectronic,3rded.Thenwaitagain,callagain,waitagain,callagain,asmanytimesasyoulike,oruntilsomeoneanswersortellsyoutogoaway!AnOldTimer’sQuirkIfyouwanttomakeaDXcontact,listenarounduntilyouhearaDXstationsendingCQorendingaQSO,andthencallthatstation.Mosthams,beingpoortypists,didn’tfindthatconstrainttroublesome.IobtainedacollapsiblewhipantennafromMFJEnterprisesthatextendscontinuouslyupto5meterstall,soIcansetittoanyfrequencyonanyhambandfrom6metersthrough20meters.Butthetheoryoflawandpracticalrealitysometimesdiverge,andthisbandoffersagoodexampleofthatcircumstance.Foragivenconductorsizeandspacing,four-wirelinehasalowercharacteristicimpedancethantwo-wireline;thefour-wirelineisinfacttwotwo-wirelinesconnectedinparallel.Notonlydidmoreofthe40-meterbandserveashometoshortwavebroadcaststations,butalsoitseems(ifmymemoryserves)thatthereweremoreofthemperunitspectrumspan.IfIcan“crackapileup”with10watts,Iknowthatmyantennaisdoingagoodjob!However,beforeIcallanybody,Ialwayslistentoseewhatthecontestexchangesinvolve,andalso,ifpossible,tofindoutwhichcontestitisandwhereit’shappening.Inadouble-conversionreceiver,thelowsecondIFmakesitpossibletoobtainbetterselectivitythancannormallybeobtainedwithasingle-conversiondesign.Split-FrequencyModeWhenaDXstationoperatesinsplit-frequencymode,itsoperatorwantsyoutocallonasignificantlydifferentfrequencyfromtheoneonwhichsheorheistransmitting.Well,thehamradiolicensinglevelsusedtobealotmorecomplicatedthantheyaretoday.IfthePIVratingisnotgreatenough,thediodeordiodesinasupplywillconductcurrentforpartofthereversecycle,degradingtheefficiency.30MetersThehambandat30metersextendsfrom10.100MHzto10.150MHz,soit’sarelativelysmallbandcomparedwithmostotherHFbands.TheDeadBandDelusionThe“upperHFbands,”especially10and12meters,occasionallytrickusintothinkingthey’re“dead”wheninfactthey’remerelyneglected.ThisresistancerepresentsRRalone.Therefore,thedetectoroutputrepresentsafaithfulreproductionoftheincomingsignaldata.TomaintaintheproperACfrequency,asimplegenerator’senginemustrunataconstantspeedunderconditionsofvariableload.•TheHFbandsdon’thave“closedrepeaters”thatcanrenderVHFoperationuselessandpointlessforhamswhodon’tknowthetonesquelchfrequencyfortherepeaternearestthem.IgnitionNoiseIgnitionnoiseisimpulsenoisegeneratedbytheelectricarcsinthesparkplugsofaninternalcombustionengine.Eachpairofdiagonallyoppositeconductorsisconnectedtogetherateitherendoftheline.DoubleconversionreceiversusetwomixersandtwoIFchains.Theearthandionospherebehavelikeconcentric,sphericalsurfacesofamassivecapacitor,withthetroposphereandstratosphereservingastheinsulatingmaterial(calledadielectric)thatkeepsthechargesseparated.Plainoldlampcord,alsocalled“zipcord,”worksgreat.Inaddition,theBaudotnonalphanumericsymbolsetislimited.Ofcourse,youcancircumventtheneedforanti-VOXbyusingaheadsetinsteadofaspeakerforreception.•InChap.YoucanfindthemontheWebatwww.arrl.org/ares.Mosthamssticktograyscaleimagesandvideostoconservespectrumspaceandgetthebestpossibleimageresolution(detail).Youmustmakesure,however,nottorunmorethanabout50wattsRFoutputifyouusesmallcoaxforthefeedline;otherwise,highcurrentsorvoltagescancauseheatingandarcingthatdestroytheline’sdielectric.(Ifyouusethemicrophoneinputjackonyourcomputer,you’llprobablygettoomuchaudio,withconsequentdistortion.)Setthelevelonthesoundcardofyourcomputerforacomfortablevolumeatthecomputerheadsetjackorspeakerswhenyourradio’saudiogainissetclosetothemiddleofitsrange.Butevenifyouonlywanttolistentobroadcastsonapartoftheradiospectrumlargelyforgotteninthefuryoflatter-daydigitalmadness,thisbookhassomethingtoofferyou.Grayarrowsrepresentunusedoutlets.Oneofthemostpopularofthesemodes,knownasphase-shiftkeying(PSK),conveystextbyvaryingthephase,ratherthanthefrequency,ofthecarrierwave.Theresultingspectrumsavingswouldallowyoutofitmorethantwiceasmanysignalsintoaspecificrange,orband,offrequencies,asyoucoulddowithAM.FIGURE7-7DirectivityplotforahypotheticalantennaintheH(horizontal)plane.IcandoitifI’minagoodmood,soIstillfeel“qualified.”Infact,onaparticularlyfineday,Icanmanage25wpm!Irecommendthatyouuseacollege-ruledspiralnotebookalongwithareliablemedium-pointrollerpenthatwon’tsmear.Mostreceiverstodayhaveadequatesensitivity,sothat’snotaprimarylimitingfactorinthedynamicrangeofareceiver.Thehighervoltagecircuitstakeadvantageofbothcomponentsofthesplit-phaseelectricalsystemthatmosthomeshaveintheUnitedStates.It’sagreatplaceinthespectrumforworkingDXwhenconditionsallow.Whymakeafooloutofyourselfinfrontofthewholeworld?Allofthesefactorswillaffectwhichbandyouchoose,andwhereinthatbandyouoperate.Somedevicesneedonlyasmallcurrentatalowvoltage.Mostoperationthesedaystakesplacethroughrepeaters,whichreceivesignalsonacertainfrequencyandthenretransmitthemonslightlydifferentfrequencies.SomeAmateurRadiooldtimerswilltellyouthatthisevolutionofeventshasharmedhamradio,bringingin“lowqualityoperators.”Ithinkthattheoppositehashappened.Figure7-10offersagenericexampleoftherelativedimensionsofathree-elementYagi.Thedirectorhasaperimeterof0.95to0.97wavelength,thedrivenelementhasaperimeterofexactly1wavelength,andthereflectorhasaperimeterof1.03to1.05wavelengths.Whereinyourhomedoyouwantyourrigtoreside?Figure1-2showsmyverticalantennadesignedtooperateat14MHz,oneofthemostpopularhamradiofrequencybands,alsocalled20meters(approximatelythelengthoftheradiowavesatthatfrequency).Ifyouhavedonemuchoperatingonthehamradio80-meterand75-meterbands(3.500MHzto4.000MHz),you’llalreadyhaveagoodideaofhowthingsworkonthe90-metershortwavebroadcastband,andviceversa.IttakesintoaccountnotonlytheNQsensitivityofareceiver,butalsoitsabilitytoreproduceaweaksignalwithminimumdistortion.SquelchingAsquelchsilencesareceiverwhennoincomingsignalsexist,allowingreceptionofsignalswhentheyappear.Otherlinearscan’tprovidethemaximumlegallimitbutinsteadgowithsomethingless,suchas700wattsor1000watts.NewAdvancedlicensesarenolongerissued.Alimiterpreventsnoisefromgettingstrongerthansignalswithinthereceiverpassband.SwitchtheapplianceonwhilewatchingtheDigiPanwaterfall.IntheUnitedStates,youdon’tneedanysortoflicensetoengageinradiolisteningatanyfrequency.•WithQRP,you’llbelesslikelytohaveproblemswith“RFintheshack”ifyouuseanend-fedrandomwireantenna.AtLFandVLF,asmallloopmustcontainnumerousturnsofwire;asthefrequencygoesdown,thenumberofrequiredturnsgoesup.Accordingly,engineersmayspeakofeitheraudiospeechcompressionorRFspeechcompression,alsoknownasenvelopecompression.Asthefrequencyrises,andespeciallywhenitgetsabove3MHzorso,obstructionshavemoreblockingeffectondirectwaves.Stringthewireupashighabovethegroundasyoucangetit.Onceyoucansendabout15wpmthatway,youcanswitchtoanelectronickeyer.Othercableshaveanuninsulatedcenterconductorandathinlayerofpolyethylenejustinsidethebraid(Fig.FIGURE2-4Nomographshowingtheshortwavebroadcastbandsonalinearscaleaccordingtofrequency.Thetransformerinaradioreceiver,forexample,canbephysicallysmall.Ideally,thecoilshouldgonearthemiddleoftheelement,althoughitcanworkatanypointfromthebasetoroughlythree-quartersofthewaytothetop.Figure7-15Dshows“window”typetwinlead.VoicesonWavesAnaudiovoicesignalcomprisesfrequencyelementsthatliemostlyintherangebetween300Hzand3kHz.Youcanmodulatesomecharacteristicofaradiowave,alsocalledaradio-frequency(RF)carrier,withanaudiovoicewaveform,therebytransmittingthevoiceinformationovertheairwaves.Inadditiontohavingreasonablesizethemselves,antennason15metersdon’thavetobemountedveryfarabovethesurfacetoprovideexcellentDXperformance.Repeatersexiston1.25metersandespeciallyon70centimeters,similartotheoneson2meters.Ifyouhaveobservedreadingsof0foreverystepintheforegoingprocess,thenyoucanhaveconfidencethatyouroutlet’s“thirdhole”isproperlygrounded.ThetypicalhamradioRTTYspeed,equivalentto60wpminplainEnglishtext,is45.45baud.Thespacesbetweencharactersarethreebitslong,andthespacesbetweenwordsandaftersentencesaresevenbitslong.YoucanuseashortwaveradioreceivertotunethroughthosesidebandsandhearVLFsignalsatthesumanddifferencefrequencies.Oftentheproblemmustberesolvedin,oratthelocationof,theoffendingdevice.ManyDXstationoperatorswantyoutocallonafrequencyotherthantheirowntransmittingfrequency.Ifso,you’vewitnessedtheducteffect!IonosphericFlayerpropagationhasoccurredon6meters.Ifyouneedtorefreshyourmemory,IrecommendthelatesteditionofmybookTeachYourselfElectricityandElectronics.SomeCWaudiofilterscancutthebandwidthdownto50Hzorlessforreceptionatslowspeedsunderexceptionallyadverseconditions.FIGURE1-11Abalancedmodulatorusingtwotransistors.Power-LineNoiseUtilitylines,inadditiontocarryingthe60-HzACthatthey’remeanttotransmit,carryothercurrents.Sometimestheycarriedontheiractivityon20metersaround14.030MHz.Iwon’tidentifyanyofthemspecifically,butifyouwanttoknowalittlebitabouttheseguysandgals,doanInternetsearchonthephrase“FiveStarOperatorsClub.”InevergotuptoFiveStarstatus(80wpmormore),butIrecallhavingaQSO(conversation)withaCaliforniagalat68wpm.Thisgeometryproducesaunidirectionalradiationpattern.IfyouhappentoknowtheMorsecodeandcan“copy”itatareasonablespeed,youmightmakesenseoutofsomeofthesesignals.Therefore,forexample,ifyouwind100turnsofwirearoundaplastichoopthat’sonly0.1wavelengthincircumference,you’llendupwithalowradiationresistanceeventhoughthetotallengthofwireequals10fullwavelengths!Asmallloopexhibitsthepoorestresponsetosignalscomingfromalongitsaxis,andthebestresponsetosignalsarrivingintheplaneperpendiculartoitsaxis.Youcantake“UP”tomean“Pleaserespondakilohertz,ortwo,ormaybethree,abovemyfrequency.”Ofcourse,“UP1”means“Pleaserespondapproximately1kHzabovemyfrequency.”TipWheninsplit-frequencymode,DXandotherrarestationsalmostalwaysrequestthatyoucallonahigherfrequencythantheonethey’resendingon.•Theaudioamplifierbooststhedemodulatedsignaltoalevelsuitableforaspeakerorheadset.FIGURE7-1Approximatevaluesofradiationresistanceforverticalantennasoverperfectlyconductingground(A)andforcenter-fedantennasinfreespace(B).FIGURE6-15ThebasemountthatIdevisedfortheATAS.Infact,whentransmitting,you’dtypeonakeyboardjustliketheoneonanycommonelectrictypewriteroftheday.End-FireArrayAtypicalend-firearrayconsistsoftwoparallelhalf-waveopendipolesfed90°outofphaseandspaced1/4wavelengthapart,asshowninFig.Thesepulsesgetsentalongwiththevideosignal.Butitwasthatradiokitthatpointedmetowardmyfinalcareer:toworkforcompaniesthatdealtwithAmateurRadioissuesandequipment,andlatertowriteabouthobbyelectronicsinbooksliketheoneyou’rereadingrightnow.Ameansoffacilitatingelectricaldischargefromanantenna,suchasalarge-value,heavy-dutyinductorbetweentheantennaandground,canalsohelp.VoltageRegulationWhenyouexpectapowersupplytodeliverhighcurrentintermittently,youcanemployapowertransistoralongwithaZenerdiodetoobtainvoltageregulation,usingacircuitsuchastheoneinFig.5-3workforanend-fedwire.Successfulmoonbouncecommunicationrequiresasensitivereceiverusingaspeciallydesignedpreamplifier,alargedirectionalantenna,andahigh-powertransmitter.Anaudionotchfilterisaband-rejectionfilterwithasharp,narrowresponse.Asaresult,theinstantaneousreceiveroutputamplitudevariesalongwiththemodulatingdataontheFMorPMsignal.Directorsnormallymeasureafewpercentagepointsshorterthanthedrivenelement(s).Aground-planeantennacanyieldamazingDXresultson12meterswhenpropagationconditionsaregood,andyoucanbuildonewithhardware-storeparts!Theradiatingelementmeasuresabout2.9meterstall.Andtheantennaitselfcanbemodest;agroundplaneordipoleonlyafewmetersabovethegroundwilldothejob!Ofcourse,youcanrunhigherpowerandusemoresophisticatedantennasifyouwant,butQRP(lowpower)operationwithsimpleantennashasprovengreatfunforalotoftechnicallyorientedhams,myselfincluded.Noisefigure—Astheamountofinternalnoiseareceiverproducesgoesdown,theS/Nratioimproves,ifallotherfactorsremainconstant.7-4.TipAlthoughSWRservesasasignificantindicatorofantennadesignquality,it’snotthe“endall”figureforanalyzingorexpressingyourantenna’sperformance.Youhaveseveralchoicesfromthebasementtothetopfloor.Thenodescanbeinterconnectedbyterrestrialradiolinksifthey’rerelativelyneareachother.Ifyoucanaccessarepeaterusinganyradiowithouttonesquelching,thenyouhaveanopenrepeater.Waitforyourchancetopounceandsnareyourpreywithonequickstrike!Single-FrequencyModeInmostcases,DXstationswillrespondtocallson,orverynear,theirtransmittingfrequency,apracticecalledsingle-frequencymode.Somerectifierdiodesarefabricatedfromselenium,soengineerscallthemseleniumrectifiers.Solid-dielectrictwinleadisaffectedconsiderablybywetnessandicing,bothofwhichlowertheZoandincreasethelossevenmore.AdevicethatsendsandreceivesFSKissometimescalledamodem,anacronymthatstandsformodulator/demodulator.Nowimaginethatyoustringupathin,straight,losslesswireinfreespace(suchasavacuumwithnootherobjectsanywherenearby)andfeeditwithRFenergyatthecenter.AtB,thefoldeddipole.Adipoleantenna,orientedhorizontallysothatitsconductorrunsinanorth-southdirection,hasahorizontalplane(orH-plane)patternsimilartoFig.CosmicnoisecanbeidentifiedbythefactthatitcorrelateswiththeplaneoftheMilkyWay,ourgalaxy.TipTable8-3listsafewoftheexpressionsyoucanexpecttoencounterinyourvoice-modehamradiooperation.FIGURE1-9Spectraldisplayofatypicalamplitude-modulated(AM)voicecommunicationssignal.CharacteristicsMostofthetime,6metersoffersline-of-sightcommunicationsupto30or40kilometersonareliablebasis.That’swhyyou’llsometimesobserveasignificantdelayintransferringmessages.Buthamsclungtoexclusiveoperatingprivilegesinsmallsliversoftheshortwavespectrum,thanksinlargeparttoaninventorandhamradiooperatornamedHiramMaxim,andtheHFAmateurRadiobandsremainpopulartothisday.Youcanassume,inallsuchplots,thattheantennaoccupiesthecenter(ororigin)ofapolarcoordinatesystem.Thisgeneratorhasprovenitselfworthyasabackuppowersourceinwinterstormswhenutilityfailureswouldotherwisehavemeantnoheatformyhouse,asthefurnaceelectronicsandfanrequire117voltsACtofunction!FIGURE5-13Aportable,gasoline-fueledgenerator,capableofprovidingupto1600wattsofcleansine-waveACpowerat117volts.Itdoesnotrequireacenter-tappedtransformersecondary,soyoucangetawaywithalessexpensivetransformer.Thesepropertiesholdforloopsuptoseveralpercentagepointslargerorsmallerthanexacthalfwavelengthorfull-wavelengthcircumferences.Thenyou’llbeabletocarryonacontinuousvoicenarrationwithfixedimagesevery8seconds,somethinglikeaslideshow.ThewavelengthofanEMfieldcanlikewisevaryoverthewidestimaginablerange,fromquadrillionsofkilometerstomillionthsofamillimeter.Amodesthamradiostationfitseasilyonadesk,andhasafootprintroughlythesizeofapersonaldesktopcomputer,keyboard,andmonitor.WhenyouoperateacommunicationscircuitslightlybelowtheMUFandthentheMUFsuddenlydrops,arapidandcompletesignalfadeoutoccurs.Ofthatactivity,nearlyallgoesthroughrepeaters.Inparticular,youmightnotbeallowedtouseyourtransmitterwhiledrivingthevehicle.Becauseofthespecificlengthofthetransmissionline,thetransmitter“sees”alow,pureresistanceattheoperatingfrequency.IthasastandardthreadedbaseofthesamesortusedwithCBwhips.Iwon’tgetintothedetailsofthatcommunicationsschemehere,butifyouwanttogetagoodideaofwhatWSJTis,Googleit!MoonbouncePropagationSomeradioamateurs,blessedwiththecashforanelaboratestationandadesirefortechnicaladventure,engageinEarth-moon-earth(EME)communications,alsocalledmoonbounce,atVHFandUHF.YoucanexpressEMwavelengthasthephysicaldistancebetweenanytwoadjacentpointsatwhicheithertheelectricfieldsorthemagneticfieldshaveidenticalstrengthandorientation.Ifyouwantanewradio,amobileCBtransceiversuchastheoneshowninFig.AnEMPcancontainafantasticamountofpowerforashorttime.Itookadvantageofthosesessionstogetmyspeeduptothe13-wpmlevelthatIhadtodemonstrateduringmyGeneralClasslicensetestin1967,andalsotogetuptothe20-wpmlevelthatIneededinordertopasstheExtraClassexamin1973.•Chapter6offersinformationonhowtosetupmobileandportablehamradiostations,andrelatesmyownexperienceoperatingthesestationtypes.Theseso-calledmixingproductsproduceintermodulationdistortion(IMD)orintermodthatcanspawnmultipleimagesinsidethereceiver.Youcangetaroundthepracticalheightlimitationformobileantennasbyinsertingacoilintheradiatingelementofashortantennatolowertheresonantfrequency,makingitelectricallylongerwithoutmakingitphysicallytaller.Tonesquelchinghaslargelysolvedthisoccasionalproblem,butitcanalsokeepout-of-townmotoristsfromaccessingtherepeaterinanemergencyunlesstheyknowtherequisitetonefrequency.FIGURE3-3TheMMTTYprogramdisplayforBaudotincludesatextdisplaywithadjustablebackgroundalongwiththreedifferenttuningscopes.Fornow,keepinmindthatyou’lldobestintermsofantennaefficiencyifyouuseaslargeanantennaaspossible,operateonthehighestworkablefrequency,anddrivethebiggestvehicleyoucanfind!AdvantagesofVHFandUHFMobileWhenyoudecidetosetupamobilehamradiostation,youhaveachoicebetweenVHF(thebandsat50MHzandup)orHF(thebandsbelow29.7MHz).Ifyouknowhowtoconnectandarrangethewiresproperly,itdoesn’tmatterfromasafetystandpointhowmuchyousnarlthemup,althoughyoumightwanttoaffixlabelsonthecordsneartheirendconnectors(oneachend)sothatyoudon’tgetthemconfusedwitheachotherwhentheinevitablemalfunctionoccursandyouhavetopulloutandreplaceoneofthecomponentsofyoursystem.Themodulatingwaveformappearsasadashedcurve,andthepulsesappearasverticalgraybars.Setthemicrophonegain(orinputsensitivity)tomaximum.Thosecurvesindicatefallingfrequenciesasthemotorslowsdown.Azeppelinantennaworkswellatallharmonics(whole-numbermultiples)ofthedesignfrequency.However,thelossperunitoflengthofsuchlineexceedsthatofopen-wireorladderline.(Thoseparticularfrequenciesaren’tanabsoluterequirement,butthey’vebecometheinformalstandard.)Someprogramsdisplaytheaudiofrequencynumbersforyou;withothers,you’llhavetoguess,andthat’swherethegraphicaltuningaidsreallyhelp.7-15A,thenyoucancalculatetheapproximatecharacteristicimpedanceasZo=276log10(d/r)FIGURE7-15Open-wireline(A),ladderline(B),tubularline(C),windowline(D),ribbonline(E),andfour-wireline(F).IntheUnitedStates,thestandardACutilityprovides117volts,giveortakeafewpercent,so15ampswouldgiveyoutheabilitytopowerarigthatdemandsupto117volts×15amps=1755volt-amps.Duringthatsortofopening,youcancommunicateinmuchthesamewayasyoucandoon10metersundersimilarcircumstances.Youmayusetheworkforyourownnoncommercialandpersonaluse;anyotheruseoftheworkisstrictlyprohibited.CharacteristicsThe40-meterhambandtreatssignalsjustaboutthesamewayasthe41metershortwavebroadcastbanddoes.Duringtheday,youcancommunicatereliablyallovertheglobewhenconditionsaredecent.Atsomepoint,youshouldstarttoseetextonthedisplay.•AnadjustableIFpassbandcompensatesforthefactthatdifferentmodesoccupydifferentsignalbandwidths.Inadditiontocheckingouttheexperimenterson1750meters,youmighttunedowninfrequencyalittlewaysandhearhamradioexperimenterstestinglow-powertransmitterson136kHz(2206meters).Thatroutenecessitatedalongfeedline—over150feetofcoaxialcabletoa7-MHzdipole10feetofftheground.Youcanstringuparandom-wireantennainanyfashionandtuneittoresonancebyusingatransmatch,unlessithappenstobeclosetoanexactmultipleof1/2wavelengthlong.HeavyportablestationscanworkonHF,VHF,orUHF,butlightmobilestationsusuallyworkonlyonVHFandUHF.Asstategovernmentsgrowmoreandmoreeagertolegislatecommonsense,moreandmoreregionsandmunicipalitieswilllikelyforbidsometypesofhamradiomobileoperation,ifnotallofit(exceptwhileparked).IhaveusedthisschemeforreceivingsignalsatVLF,inconjunctionwithaVLFconverterandashortwavereceiver,withexcellentresults.CharacteristicsLike80metersand160meters,the60-meterbandworksbetterforlong-haulcontactswhenmost,orall,ofthesignaltravelsoverthedarksideoftheearth.Thisphenomenonhasfascinatedscientistsforwelloveracentury,eversince“electromagneticpioneers,”suchasHeinrichHertz,GuglielmoMarconi,andNikolaTesla,discoveredthatEMfieldscantraveloverlongdistanceswithoutanyhumanmadeinfrastructure,suchaswires,cables,opticalfibers,orsatellites.That’sthedifference,eithernegativeorpositive,betweentherepeater’sinputandoutputfrequencies.Plugalongthree-wireextensioncordintoanoutletwithaknownelectricalgroundatthe“thirdhole.”3.TipAshortwavelistenerintheUnitedStatesneednotobtainalicensetoreceivesignals,butingeneral,alicenseisrequiredifshortwaveradiotransmissioniscontemplated.Duringthedaylighthours,signalscantravelafewhundredkilometers,significantlyfartherthantheydoonthelowerfrequencies.Soinfact,evenifthelegallimitis1500wattsbutyoucangetawaywith150wattstomaintainacontact,thentechnically,youshouldscalebackyour“rig”to150wattsoutput.FIGURE6-7AheavyportablestationdeployedinthediningareaofthebunkhouseattheStargazerRanchinMeeteetse,Wyoming,March2014.Atoneorpulseappearsinthereceiveroutputforaparticularbitif,butonlyif,theaveragesignalvoltageexceedsacertainvalueoverthedurationofthatbit.ButatVHFandUHF,youcandoquitewell!Somevendorsoffer1/2-waveor5/8-waveVHFandUHFmobileantennasthatoptimizetheefficiencybymaximizingtheso-calledradiationresistance.5-10.They’reeasiertousethantheoldmanualones,andtheyalsoallowyoutoputthetunerattheantennafeedpoint,whereitcanensurea1:1SWRalongtheentirelengthofyourfeedline.Inhamradio,theexpressionreferstothelineorcablethatconnectsyourtransmitterandreceivertoyourantenna.Atypicalsunspotmeasuresfartheracrossthanthediameteroftheearth!Thebiggestonescangrowtoseveralearthdiametersfromoneedgetotheother.Themaindifferencebetweenfixed-frequencycommunicationsandspread-spectrumcommunications,whenthebandgetscrowded,liesinthenatureofthemutualinterference.Thereare12availableoutletsinthepowerstrips,10ofwhichareinactiveuse.Itisdifficulttoconstructatwo-wirelinewithacharacteristicimpedanceoflessthan150ohms,butfour-wirelinecanbemadetohaveaZovalueaslowas75ohms.ThisnotionissimplefordigitalmodesbutalittlemorecomplicatedforUSB.Figure2-2showsanexample.TheacronymVOXstandsforvoice-operatedtransmission(hamsoftenabbreviatetheword“transmission”asTXorX).Abasicrepeaterincludesareceiver,atransmitter,anantenna,andanisolatingnetworkcalledaduplexer(Fig.AnOldTimerRemembersWhenIservedasaneditorialassistantatARRLHeadquartersin1978–1979,IhadanapartmentinWestHartford,Connecticut,onthetopfloorofanoldthree-storyhouse.Thisfeaturecanproveespeciallyusefulinmobileoperation,whenyouneedbothhandsforsuchthingsasoperatingothercontrols(yoursteeringwheel,forexample).Thatway,Iwon’tfrustrateseriouscontestoperatorswho’llwanttogetmeoutofthewayandputmeintheirlogswithaminimumof“mussandfuss.”Don’tBeaLid!Whenabandgetscongested,you’lleventuallycomeupagainstsomebodywho’lltransmitontopofyou,insultyou,orotherwiseactlikeajerk.SignalReportingWheneveryoumakeacontact,you’llwanttoknowhowstrongyoursignalisattheotherend.Thegroundrodshouldgodownatleast8feet(2.4meters),though,andbeabout3feet(1meter)awayfromthehousefoundation.InthecircuitatD,diodesareused.Communicationbecomesmostdifficultnearthetimeofthenewmoon,whenthemoonliesnearalinebetweentheearthandthesunbecausethesungeneratesstrongradiowaves(aswellasinfrared,visiblelight,ultraviolet,andXrays).FIGURE7-14Coaxialcablewithasolidorfoameddielectric(A),andcoaxialcablewithadielectriccomprisingmostlyair(B).Thebestbandsforthisactivityare12,10,and6meters.YoucangetawaywithothertypesofFETsatlowerfrequencies.Ifigureditconstituteda“longshot,”butadverseoddsneverdauntedmepriortothattime(norhavetheysince).AtB,theE-plane(elevationplane)plotasviewedfromapointontheearth’ssurfacefarfromtheantenna.FIGURE1-19Blockdiagramofadiversityradioreceptionsystem.5-13)formstheheartofmyemergencybackuppowerensemble.Ingeneral,thehighertheintermediatefrequencyofareceiver,thebettertheimagerejection.Figure7-11Ashowsanexampleofaconventionaldishfeed.•GeneralClassoperatorscanusethespansfrom21.025MHzto21.200MHzfordigitaloperation,and21.275MHzto21.450MHzforphoneandimagingcontacts.•Novices,Technicians,andTechPlusoperatorscanusethefrequenciesfrom3.525MHzto3.600MHzforCWoperationonly,withamaximumof200wattspeakenvelopepower(PEP)output.TipYou’llreadmoreaboutfeedlineslaterinthisbook.TroposphericPropagationAtfrequenciesaboveabout30MHz(wavelengthsshorterthanabout10meters),theloweratmospherebendsradiowavestowardsthesurface.1-9,alltheaudioinputenergyexistsatorbelow3kHz,sothebandwidthofthemodulatedsignalequals6kHz.That’stypicalofAMvoicecommunications.Youcan’tlegallyusehamradioforconductingbusiness.Intechnicalterms,it’stheinstantaneouspoweratthepeaksofthemodulationenvelope.2.Youshouldhaveageneratorwithplentyoffuelonhand,batteries,andsparebatteries,orastand-alonesolarorwindenergysystem.Becauseofitsnon-symmetricalgeometry,thezeppantennaallowssomeRFradiationfromthefeedlineaswellasfromtheantenna.AreYouAstute?Renew!AllAmateurRadiolicensesremainvalidfor10yearsfromthedateofissue.AllocationsbyLicenseClassThe80-and-75-meterbandcontainsvarioussegmentsallocatedaccordingtolicenseclass.SuperheterodyneReceiverAsuperheterodynereceiver,alsocalledasuperhet,usesoneormoreLOsalongwithsignalmixerstoobtainaconstant-frequencysignal.LongwireAwireantenna,measuringafullwavelengthormoreandfedatahighcurrentpoint(currentloop)oratoneend,constitutesalongwireantenna.Pulse-WidthModulationYoucanmodulatetheoutputofanRFtransmitterbyvaryingtheduration,orwidth,oftheindividualsignalpulsestoobtainpulse-durationmodulation(PDM),alsoknownaspulse-widthmodulation(PWM),asshowninFig.Afull-wave,center-taprectifierhasatransformerwithaconnectioncalledatapatthecenterofthesecondarywinding(Fig.Thegainanddirectionalcharacteristicsofgiantloopsarehardtopredict.PhasedArraysAphasedantennaarrayusestwoormoredrivenelements(radiatorsconnecteddirectlytothefeedline)toproducepowergaininsomedirectionsattheexpenseofotherdirections.StickwiththestandardphoneticsaslistedinTable8-2.InMarchof1966,IgotmyNoviceClassLicense,which,backinthatday,offeredseverelyrestrictedprivileges.Thetransmittingstationmustfrequentlypausesothatitsownreceivercanpickupandcheckrequestsfromtheremotereceiver.FrequencyModulationRadiohamsuseFMalmostentirelyontheVHFandUHFbands,thatis,6metersandshorterwavelengths(50MHzandabove).I“cannibalized”afinishedshelffromakitchencabinettoservethisnoblepurpose.Freebandactivityreachesitspeakduringtimesofmaximumsunspotnumberswhenlong-distancecommunicationcanoftentakeplace.Inmostradios,youcansqueezethemicrophonetoclosetheswitchandtalk.Someantennashavesmallmetalspheresattheendstominimizetheoccuranceofcoronae.615).Sensitivity—Themostcommonwaytoexpressreceiversensitivityistostatethenumberofsignalmicrovolts(millionthsofavolt)thatmustexistattheantennaterminalstoproduceacertainsignal-to-noiseratio(S/N)orsignal-plus-noise-to-noiseratio(S+N/N)inrelativeamplitudeunitscalleddecibels(dB).Thereverseholdstrueforastep-uptransformer,inwhichtheoutputvoltageexceedstheinputvoltage.3-5.Thevariablecapacitorallowsyoutotunethesystemtoresonance(optimumsignalconditions)atthedesiredfrequency.Therearetwosets,calledchains,ofIFamplifiers.Theinnerwireiscalledthecenterconductor,andtheouterconductoriscalledtheshield.Otherhamsprefertheslowlifeingeneral,andusetheradioasaformofentertainment(orlonelinessmitigation).Allofthesethingsgettheirpower,eitherdirectlyorindirectly,fromthe117-voltutilitysystem.Knownasidleinsertion,itkeepsthereceiversynchronizedwiththetransmitterduringpausesinthetransmission,sothatnoiseburstsorstraysignalsdon’tthrowthereceiveroffanddegradetheperformanceofthesystem.AtB,thecoaxialdesign.Unfortunately,HFpacketcommunicationsisratherinefficientandslowbecauseofvariablepropagationconditions.Hamshaveatermforoperatorslikethat:lid.Isatforhoursinfrontofthatradio,fascinated,listeningtothebeepsandbuzzesandtonesandticksthatWWVproduced(oneofwhichIrecognizedasasoundeffectinanepisodeoftheoriginalStarTrektelevisionseries).Thistypeofcableiscalledhardline.Itdoesn’tmatterwhetherornotthewirehasinsulation.Thetransmitterremainsonforashorttimeafteryoustopspeaking;thedelaypreventsyourradiofrom“trippingout”duringshortpauses,aphenomenonthatmostpeoplefindexasperating.Ofcourse,youmustadheretothelicenseclassrestrictionswhenchoosingafrequency.Intechnologicallyadvancednations,mostgovernmentandbusinessentitieshavemovedtheiroperationstotheveryhighfrequencies(VHF)from30to300MHz,theultrahighfrequencies(UHF)from300MHzto3GHz,andthemicrowavefrequenciesabove3GHz.Thisongoingshifthasgivenrisetotalkoflettinghamradiooperatorsusesomeadditionalpartsoftheshortwavebandthattheyoriginallydiscovered.FIGURE3-13AsinglelineinananalogFSTVvideoframeasitwouldappearonalaboscilloscope.Ifaplanetlacksanionosphere,communicationmightworkdowntoextremelylowfrequencies,indeed—evenbelow1kHz—iftheplanetconductselectriccurrentswellenoughbecausethewaveguideeffectwon’tshortoutEMfieldsnomatterhowlongthewavelengthgets.Nomatterhowbadconditionsgot,Ialwayshadagreattime.Youcanfindoutletslikethatjustaboutanywherethesedays.Ifyouwanttotalkabouttheweatherorsomeothermundanetopic,ofcourse,anythinggoes,exceptspreadingstufflikefalsehurricanewarnings.ThefeedlinefortheantennashowninFigs.Engineerscallthissignalthefirstintermediatefrequency(IF),whichcanbefilteredtoobtainenhancedselectivity.FIGURE7-13Acornerreflectorthatemploysadipoleantennaasthedrivenelement.ThatYagihada“clearview”ofthehorizoninalldirectionsfromitsvantagepointonthatslopingroof.TheARRLHeadquartersstationW1AWstilltransmitsofficialbulletinsregularlyusing45.45-baudBaudot.PowerTransformersWecancategorizepowertransformersintwogeneralways:step-downorstep-up.Ifyoudon’tfollowtheserulesstrictly,backfeedcanoccur,inwhichelectricityfromthegeneratorgetsintotheutilitylinesnearthehomeorbusinesswherethegeneratoroperates.Onceyougetonthebusinessendofapileup,you’llfindoutwhyrareDXstationssometimesbehaveinstrangeandseeminglyneuroticways.41MetersIfyou’reahamradiooperator,youhaveagoodideaofwhatconditionsarelikeontheshortwavebroadcastbandthatgoesfrom7.200MHzto7.600MHz.IfyouprefertouseSSBonthe40-meterhamband,you’vedoubtlessheardsomeofthosepowerfulbroadcaststationsinthespanwherethebandsoverlap(7.200MHzto7.300MHz).Figure7-15Bshowsatypicalladder-type,open-wireline.Feelfreetoskipaheadnowifyoudon’tknowthedifferencebetweencoaxiallineandopen-wireline.Figure715Cshowsanend-on,cross-sectionalviewofatubularline.Let’sdefineafewimportantcriteriaforreceiveroperation,andthenwe’lllookatacoupleofcommonreceiverdesigns.Theexactvaluedependsonthelinetype,theconstructionmethodused,andthenatureofthedielectricmaterialthatseparatestheconductors.Thegist:Openwirehaslowerlossthancoaxialcable,butit’shardertoinstallproperly.FIGURE3-2Akeyboardforsendinghigh-speedcode,anartthatenjoyedpopularityinthe1970s.SunspotsandShortwaveRadioThesun’ssurfacehostsviolentstorm-likephenomenathatweseeassunspotsbecausetheyradiatelessvisiblelightthantherestofthesolardisk.6-13)forthebestpossibleelectricalcontact,ensuringthatproblemswon’toccuratmaximumcurrentdrain,whichinmycasecanrunupwardsof20ampereswiththeradiokey-down.Atthelowestshortwavefrequencies,you’llrarelyobserveaskipzone.IfyouhaveaGeneral,Advanced,orExtraClasslicense,youcanuseanyfrequencyinthebandandputoutupto1500wattsPEP.ThebestcomprehensivereferencethatIknowofforthesubject,TheARRLOperatingManual,canserveyourneedsinmoredetail,onceyou’vereadthischapteranddecidedwhatyoulikebest.DuringmyweekattheStargazerRanchinthewinterof2014,Igotagreatchancetodoit!Anunusualoverthe-poleopeningatnightonfrequenciesupto24MHzmadeforfascinatingcontactswithotherhamsinsuchplacesasRussia,Japan,andSouthAmerica.MobileAntennaConsiderationsInpracticalsituations,youcan’toperatemobilestationsbelowabout24MHzwithoutplacinganinductorintheantennaelement.Inaddition,receivingtypeTVribboncan’thandleasmuchpowerasagoodopenwireorladderlinecan.Thetransmitterretransmitsthesignalatthesametime,usingthesameantennaasthereceiver.So-called“75-metersideband”or“75-meterphone”enjoyshugepopularityintheUnitedStates,especiallyonwinternightswhenyoucanhearsignalsfromalloverthecontinentwithease.BinaryPSKInhamradio,themostpopularvariantofPSKsplitsthecarrierintotwoopposingphases,soit’ssometimescalledBPSKforbinaryphase-shiftkeying.Youmightask,“Whyshouldhamsspendtimeworkingonnewdigitalcommunicationsmodeswhenperfectlygoodones,likeCWandRTTY,alreadyexist?”Asanoldtimerinthishobby,Icananswerthatquestionintwoparts:(1)Technicallyinclinedradiohamshaveaninborncompulsiontodreamupnewmodesandgetthemtowork;and(2)thesepeopleenjoyanendlessquestforminimizingerrorratesandmaximizingdigitalcommunicationsefficiency.Anotherspeedspecification,calledbaud,expressesthenumberofsignal-statechanges(frommarktospaceorviceversa)persecond.•Dynamicrangeistheratio,indecibels,betweenthelevels,inmicrovolts,ofthestrongestsignalthatcanexistattheantennaterminalswithoutcausingappreciabledistortioninthefrontend,andtheweakestsignalthattheradiocanbringin.Kybett,Harry,AllNewElectronicsSelf-TeachingGuide,3rded.You’llobservetroposcattermostcommonlyatVHFandUHF.Sincethe“repeaterrevolution”inthe1970s,propagationforecastsandconditions(andthesciencethatgoesalongwithit)areoflittleornoconcerntoradiohamson2meters.CodeRequirement:GoodorBad?Figure7-7showsahypotheticaldirectivityplotforaunidirectionalantennapointednorth.TheratioofthemaximumRFvoltagetotheminimumRFvoltage,orthemaximumcurrenttotheminimumcurrent,iscalledthestanding-waveratio(SWR)ontheline.Gallium-arsenidefield-effecttransistors(GaAsFETs)areknownforthelowlevelsofelectricalnoisetheygenerateatthesefrequencies.Theseantennas,ineffect,supplytheirownRFgroundatthefeedpoint.Ahalf-wavedipolemeasuresabout20metersfromendtoendonthisband.Figure1-15isablockdiagramofadirect-conversionreceiver.Maybeafterreadingthisbookyou’llseewhatImean!ElectromagneticFieldsInaradioortelevisiontransmittingantenna,electronsmovebackandforthbetweentheatomsinametallicwireortubing.SurfaceWavesAtfrequenciesbelowabout10MHz,theearth’ssurfaceconductsalternatingcurrent(AC)quitewell,soverticallypolarizedradiowavescanfollowthesurfaceforhundredsoreventhousandsofkilometers,withtheearthhelpingtotransmitthesignals.The“upperHFbands”at20,17,15,12,and10metersusuallyofferbetterconditionsduringthedaylighthoursandinthespringandsummer;the“lowerHFbands”at40,60,80,and160metersusuallyworkbetteratnightandduringthefallandwinter.Thesimplestpower-supplyfilterconsistsofoneormorelarge-valuecapacitors,connectedinparallelwiththerectifieroutput,asshowninFig.Theoptimumspacingbetweentheelementsofadriven-element/reflectorYagiis0.15to0.2wavelength,withthereflectortuned5%to10%percentlowerthantheresonantfrequencyofthedrivenelement.Ihadsuspected“dirtintheether,”butnotthatmuch!Figure2-13showsmyownDigiPandisplayofdirtyelectricityfrom60Hztomorethan4000HzintheworkspacewhereIwrotethisbook.Likespeechcompression,itcanbedoneeitherintheaudioorRFstages.ExamplesMyheavyportablestationoriginallycomprisedaYaesuFT-857Dcompactall-bandtransceiveralongwithadeep-cyclemarinebattery,akeyerpaddlegluedtoapieceofwoodtoserveasanarmrest,andameterthatindicatedhowwelltheradiowasmatchedtotheantenna(calledanSWRmeter,whereSWRmeansstanding-waveratio.)asshowninFig.Inradioteletype(RTTY)FSKsystems,aterminalunit(TU)convertsthedigitalsignalsintoelectricalimpulsesthatoperateateleprinter,ordisplaythecharactersonacomputerscreen.Coronaeoccurincreasinglyoftenastherelativehumidityrisesbecauseittakeslessvoltagetoionizemoistairthanittakestoionizedryair.Youmightfeelastrongtemptationtotransmit“LID”onCWorsay,“Getlost,lid”onthephone.AllocationsbyModeYoumayuseonlyCWemissionfrom144.000MHzto144.100MHz.Therangefrom144.100MHzto148.000MHzisopentoallmodesofoperationthathamscommonlyemploy,butasonthelowerbands,fast-scantelevisionisforbiddenbecauseittakesuptoomuchbandwidth!AllocationsbyLicenseClassIfyouholdanExtra,Advanced,General,orTechlicense,youmayuseanyfrequencyinthe2-meterband,subjecttotheabove-describedmoderestrictions.AstandardFSTVchanneltakesup6MHzofspectrumspace,or1000timesthebandwidthofanAMvoicesignal!Forthisreason,allamateurFSTVactivitytakesplaceontheUHFbandsat70centimetersandabove.Hefoundsomeradionoisethathecouldn’taccountfor,andthenhenoticedthatitsorientationcorrelatedwiththelocationoftheMilkyWayinthesky.AlthoughI’veneverbeenfloodedout,mybasementfloorwillgetwetifasuddencloudburstoccurs.ButIcouldusevoiceemissionsthere,andIwantedtotrysomeon-the-air“gumflapping”insteadof“brasspounding”!Repeatershardlyexistedatallinthemid-1960s,somostoperationson2metersweredoneusingAM.Front-to-SideRatioThefront-to-side(f/s)ratioprovidesanotherusefulexpressionforthedirectivityofanantennasystem.Normally,thepulseamplitudeincreasesastheinstantaneousmodulating-signallevelincreases(positivePAM).ParasiticelementsoperatebymeansofEMcouplingtothedrivenelementorelements.Inmostlines,thelossperunitoflengthincreasesasthefrequencygoesup.5-9A).Ifthemotorspeedchanges,theDCvoltagestaysthesamebecausetheregulatorcircuitholdsitconstant,sotheoutputACvoltagestaysconstanttoo.Thepowersuppliesforsuchequipmentusestep-downpowertransformers,withtheprimarywindingsconnectedtotheutilityACoutlets.GointoyourfavoriteInternetsearchengineandenterthesingleword“HamScope”tofinddownloadsites.CharacteristicsBecauseofitsabilitytoprovidespectacularworldwidecommunicationswithlowtransmitterpoweroutputunderidealconditions,10metershasacquiredthenickname“magicband.”Overdaylightpaths,especiallyinspringandsummerandinyearsnearthesunspotcyclemaximum,youcanworkDXwithlessthanawattofRFatyourantenna.It’sfuntoactas“gameinahunt,”especiallyifyoumakefor“tastygame”!(IliveinasparselypopulatedARRLsection,acharacteristicthatmakesmeanespeciallydesirabletargetincontests.)Whenyouhavea“bigrig,”however,don’tactlikeabullywithit.Thefrequencygoesup,andthewavelengthgetsshorterasyoumoveupthescale.AfterusingRTTYandBPSK31foralittlewhile,you’lllearntorecognizethosemodesbythewaytheystrikeyourears.Foratypicalwireconductor,v=0.95(95%);formetaltubing,vcanrangedowntoapproximately0.90(90%).•Transmittingasignalwhosebandwidthexceedsthelegallimitforthemode.Youcanselectbetweenawaterfalldisplayandaspectrumdisplayfortuning.AtLFandespeciallyatVLF,you’llnoticetheeffectsassoonasyoutunearadiodownthere.Chooseasitethatwon’tmakeiteasyforpeopletocomeintocontactwiththeradiatingelement(s),

eitheraccidentallyoronpurpose.Thepreselectoralsoprovidessomeextraimagerejectioninasuperheterodynecircuit.Ifyou’reusingadigitalmeter,makesurethatthedisplayindicatesavalueof0.Ifpossible,checkoutsomeradios“live”atahamfestorconventiontoevaluatetheminthisrespectanddecidewhetherornotyoulikethe“feel.”•Continuousreceivecoverageallowsyoutolistenallthewayfromthelowestdesignfrequencytothehighest,withoutanygaps.Wheneveryouchangethefrequencyofasignal,aninherentphaseshiftgoesalongwithit,andviceversa.On2meters,600kHzisthemostcommonsplit.It’sacompromise,though,ifyouwanttogethighDCvoltage,becausevoltagedropsconsiderablywhenyoudemandalotofcurrentfromit.Othertypesofelectricnoisedefynoiseblankers,andthebestyoucandoishopethatalimiterwillgivesomereliefbygivingthedesiredsignalsa“fightingchance”againstthenoise.RadiosequippedwithVOXallowyoutoadjustthedelaytimebetweentransmitandreceivemodesafteryoustopspeaking.There’ssomethingabouttheambienceofatypicalbasementthatlendsitselftonerdyactivitieslikehamradio,especiallythetechnicalandexperimentalvarietyinwhichIengage.Iofferalinktoallmybooksfrommywebsiteatwww.sciencewriter.netBarringsomeunforeseenmediameltdown,you’llalsofindfreevideosonthesetopicsifyouvisitandbrowsethroughmyYouTubechannel,alsolinkedthroughmywebsite.However,tropocantakeplacehere,inmuchthesamewayasitdoeson6meters.Inengineeringterms,theamplificationcurve(instantaneousoutputversusinstantaneousinput)showsupasastraightlineonagraph.DetectionofSSBForreceptionofSSBsignals,mostcommunicationsengineersfavoraproductdetector,althoughadirect-conversionreceivercandothejob.DeviationinFMandPMInanFMorPMsignal,thedeviationisthemaximumextenttowhichthemodulated-carrierfrequencyrisesaboveandfallsbelowtheunmodulatedcarrierfrequency.Thislimitisroughlythesameasitwouldbeifallthesignalswereconstantinfrequency,andhadtheirowndiscretechannels.Itcanalsocausesensitiveelectronicequipmenttomalfunction.Inpractice,it’saformofFSKsimilartoordinaryRTTY,butinsteadofusingtwodifferentwell-definedcarrierfrequencies,MFSKusesseveraldifferentwell-definedcarrierfrequencies.Alternatively,youcouldgetastrongersignalforthesameamountoftransmitteroutputpower.Coordinatenumbersindicatecompassdirection(azimuth)anglesindegrees.Adish-antennafeedsystemconsistsofacoaxiallineorwaveguidefromthereceiverand/ortransmitteralongwithahornorhelicaldrivenelementatthefocalpointofthereflector.Atypicalweightcontrolallowsadjustmentofthedot-to-spaceratiobetweenlimitsofabout1:2(“light”)and2:1(“heavy”).Twisted-wireoropen-wirelinescanletstrayRFfields,impulsenoise,andappliancenoisein,degradingreception.Inanycase,youshouldalwayslookforthisfeaturewhenshoppingforaradio.Inparticular,youcangetawayfrommost,ifnotall,sourcesofelectromagneticinterference(EMI)thatbedevilurbanandsuburbanhams’receptionatHF.Inmycase,althoughtheantennaswerealittlelessefficient,thelocationprovedsuperiorbecausehumanmadenoisehardlyexisted,andIhadaclearshottothehorizoninalldirections.Worldwidepropagationcanoccur24hoursadayhere,althoughconditionsareusuallybestoverpathsthatlieentirelyonthedarksideoftheplanet.AccessingaRepeaterInthe1970swhenIfirstgotactiveonFMrepeaterswithamobile2-meterrig,IcouldalmostalwaysfindarepeaterandaccessitwhenIcouldhearit.Sometimespeople,hearingnothingon10meters,assumeit’sdeadwheninfactit’swideopen!Icallthispsychologicalphenomenonthe“DeadBandDelusion.”SowhynotsendaCQortwo?Itcanalsoincreasetheriskofyoursufferingwithpoorradioreceptionbecauseofhumanmadeinterferencesources,suchasrogueelectricalappliances.Voltage-DoublerCircuitYoucanconnectdiodesandcapacitorstogethertodeliveraDCoutputofapproximatelytwicethepositiveornegativepeakACinputvoltage.Imagerejectionisspecifiedindecibels.Aperfectrectangularresponsewouldcorrespondtoashapefactorof1:1,orsimply1.Inthewaveguidemodeofpropagation,thetransmittingantenna,whichmustproduceaverticallypolarizedEMwave,deliversenergyintothespacebetweentheearthandionizedlayersoftheupperatmosphere.ForMorsecode,30wpmrepresentsarespectablespeed.AtB,youseeanomographoftheradio-frequency(RF)portionofthespectrum,whereeachverticaldivisionrepresentsoneorderofmagnitude.Laterstill,around1970,theFCCbroughtitbackwhentheyimplementedastratifiedschemeknownasincentivelicensing.Insertthemultimeter’sblack(negative)probetipintothe“thirdhole”intheextensioncordoutlet.Again,theirmainwebsiteiswww.arrl.orgThey’llprobablyoffertosellyousomeoftheirspecializedlicense-examstudyguides.Hamshavefullprivilegeshere,withoutanyneedtoworryaboutinterferingwithotherservices.3-11.Formusic,adeviationof±15kHzor±20kHzisrequiredforgoodsoundqualitywhenthesignalfinallyreachespeople’sreceivers.Whenthepioneersofshortwavecommunicationgot“allthewaydown”towavelengthsinthisrange,theylearned,infull,howamazingtheHFrangeofwavelengthscanget.Ingeneral,asthenumberofradialsofagivenlengthincreases,theoverallefficiencyofanyverticalantennaimproves(ifallotherfactorsremainconstant).Ifyouconnectaload,suchasyourradio,tothiscoil,anACvoltageappearsacrossthatloadaseachpointinthewirecoilmovespastthelinesoffluxproducedbythemagnets,firstinonedirectionandthenintheotherdirection,overandover.ForhamswhocantypewellandwhoadheretocommonEnglishusageinregardstocapitalizationandpunctuation,plaintext(suchaswhatyou’rereadingrightnow)BPSK31signalscomeoutat45to50wpm.Theexactfrequencytransitionpointvariesdependingonthetimeofyear.TheARRLcantellyoueverythingthatyouneedtoknow.Fourconductorsarerunparalleltoeachother,insuchawaythattheyformtheedgesofalongsquareprism(Fig.ThelocalcarrierisproducedbyatunableLOinsidethereceiver.It’sagoodplaceforexperimentersandseriousDXers.Normally,thistypeofamplifierusesaJFETorGaAsFET,andgoesbetweentheantennaandthefrontendoftheradio.Anaudiobandpassfilter,withapassbandof300Hzto3000Hz,canimprovetheintelligibilityinsomevoicereceivers.Eachsignalremainsindependentofalltheothers.Thehorizontalaxisportraysfrequency.ErrorCorrectionOneoftheoutstandingfeaturesofMFSK16isforwarderrorcorrection(FEC),aformofdataredundancyinwhichthetransmittingstationsendseverydatabitmorethanonce.Thoserulescangetconfusing.Ifyou’reaNovice,Tech,orTechPlusoperator,you’llhavetoupgradeatleasttoGeneralbeforeyoucantransmiton30meters.Atwo-elementquadcanconsistofadrivenelementandareflector,oritcanhaveadrivenelementandadirector.Coaxialcableorcoax(pronounced“CO-ax”),isusedbyamateurandCBradiooperatorstoconnecttransceivers,transmitters,andreceiverstoantennas.ThetermCassegraincomesfromtheresemblanceofthisantennadesigntothatofaSchmidt-Cassegrainreflectortelescope.Youshouldalsoscanyourcomputerwithanup-to-date,anti-malwareutilityafteryou’vedownloadedanyprogram,whetheritworksornot.Packetcommunicationsisself-correcting.Teleprinterswere,ineffect,automaticelectrictypewriters.Butnomatterwhatthefrequency(orwavelength),thelevelofsolarfluxincreasesjustafterasolarflareoccurs.Forexample,arepeatermightuse146.34MHzasitsinputfrequencyand146.94MHzasitsoutputfrequency.Bylaw,hamradiooperatorsmustavoidinterferingwiththeseservices.Inhamradio,generalconversation,especiallythelong-windedsort,iscalledragchewing.Ifyouseeamicrophoneinputvolumeorsensitivitycontrol,setittomaximum.•Novices,Technicians,andTechPlusoperatorscanusethefrequenciesfrom21.025MHzto21.200MHzforCWoperationonly,limitedto200wattsRFoutputpower.Buthamradiohandheldunitsor“handy-talkies”incorporatesophisticatedfeaturessuchasmicroprocessorcontrolanddigitalcapability,whichwalkie-talkiesrarelyhave.Forinformationaboutpossiblechanges,visitwww.arrl.org.Patienceequalspower!Phase-ShiftKeyingSeveralvariantsofRTTYemissionexistbesidesFSK.Butmany,ifnotmost,ACutilitywavescontainharmonicenergyalongwiththeenergyatthefundamentalfrequency.Conditionsonthesefrequenciesresemblethoseonthe16-meterbandthatliesabout1MHzlowerdowninthefrequencyspectrum.Thesusceptibilityorimmunityofareceivertospuriousresponsesisprimarilydependentonthedesignofitsfrontend.Thistypeofantenna,calledaloopstick,hasdirectionalcharacteristicssimilartotheordinarysmallloop.It’smanufacturedbyacompanycalledVibroplex,andinmyopinion,they’rethebest!Youcanfindtheirwebsiteatwww.vibroplex.comFIGURE3-1ApaddleforsendingMorsecodewithanelectronickeyer.Scanconvertersandcamerasarecommerciallyavailablefrommanyhammanufacturersanddealers.Ifyouwanttotranslatethespeedofatransmissionfromwordsperminuteintotheequivalentspeedinbitspersecond,multiplyby5/6.Theyresultinaneffectcalledpower-linenoise.•Adjustthetransmatchuntilthesignalsand/ornoise“peak”inthereceiver.AllocationsbyLicenseClassAllhamsexceptNovicesmaylegallyuseanyfrequencyinthe6-meterband,subjecttothemodeconstraintsoutlinedabove.Youdon’tneedalicenseintheUnitedStatesinordertoconductLowFERactivitiesthatinvolvetransmittingbetween160kHzand190kHz,aslongasyouadheretocertainrestrictions.ForordinaryBPSKoperation,IuseHamScopebecauseitcanalsodecodesignalsintheexoticmodeknownasmultiplefrequency-shiftkeying(MFSK).Theradiatingelementwillbeabout4meterstall,andtheradials,whichcanslopedownatanangleandserveasguywires,willalsomeasureroughly4meterslong,keptattheproperlengthwithegginsulators.AllocationsbyLicenseClassExtra,Advanced,General,andTechoperatorsmayuseanyfrequencyonanyallocatedhambandabove219.000MHz,subjecttotheabove-describedrestrictiononFSTV.You’llhavetoremoveanyexistingexternalscreenorstormwindow.Ifthat’strue,thenMFSK16mightsurpassCWasthemodeoflastresortinadverseconditions.Yousimplytypeinwhatyouwanttosend,andaslongasyoustayaheadoftheoutputwithyourtyping,thedevicewillgenerateperfectcodeatwhateverspeedyouselect.Whiletheentiresetofbandscoversmorethananorderofmagnitudefrequency-wiseorwavelength-wise,eachindividualshortwavebroadcastbandisnarrow,soyoucanexpectthatpropagationconditionsatthetopofanygivenbandwillcloselyresembleconditionsatthebottomofthesameband.Likewise,LFsignalsofextraterrestrialorigincan’treachusattheearth’ssurfacebecausetheionospherereflectsthembackintospace.Itwillnotlikelysurvivethehurricane-forcewindsthatassaultitatfreewayspeeds,anditcanstrikelow-hangingobstructions,suchastreebranches,utilitywires,smallbridges,andtightoverpasses.SomeradioshaveaspecialRTTYfilterthatcangiveyouanarrowpassbandtominimizeinterferencefromsignalsatnearbyfrequencies.Communicationsengineerscallthiseffectmeteorscatterpropagation.It’sthatwayforthesamereasons:80-to-75-meterwavespropagatebetterwhentheDlayerlacksionization,andthat’sduringthehoursofdarkness.PredetectorStagesWhenyoudesignandbuildasuperheterodynereceiver,youmustensurethatthestagesprecedingthefirstmixerprovidereasonablegainbutgenerateminimalinternalnoise.Stan.”Thatalmostalwaysclearsthingsup.It’llensurethatyougetthebestpossibleimpedancematchbetweenyourrandomwireandyourradio.Theaudiocircuitsinmyreceiver,mycomputer,orbothmusthavespawneditbecauseIknowthatitcouldnothavecomefromW1AW!Ifmyreceiver’saudiocircuitscanplaythistrickonme,yourtransmitter’saudiocircuitscanplayitonyou.Whenthesungoesdown,theDlayervanishesand160meters“opensup.”Becausewavesat1.8MHzaresolong,agoodantennamustbelongandhigh.QuickQuestion,QuickAnswer•Doesn’tthepresenceof10devices,allpluggedintoasinglewalloutlet,asshowninFigs.TheFCCforbidshamradiooperatorsfromtransmittingmusic,anyway!NoiseImmunity,SortOfForvoicecommunications,FMoffersbetterimmunitytostaticandimpulsenoisethanAMdoesbecausethesetypesofnoiseare,ineffect,amplitudemodulated.IfyouhaveyourradiosettoreceiveUSB,you’llfinditimpossibletotuneinanLSBsignalsothatyoucanunderstandwhattheoperatorsays.CutofftheU-shapedspadelugsfromtheaudiocordwithascissorsordiagonalcutter.LotsofCWoperatorsconcludeQSOsbysendingtheletterEtwice(ditdit).FIGURE1-18D-EAtD,aproductdetectorusingdiodes.Ifyou’re“chewingtherag,”however,youmightgoonforhours!Butevenwhenyouareinvolvedinalong,conversationalQSO,don’tgetintoextrememonologues,anymorethanyouwouldinaface-to-faceconversation(alsoknownasan“eyeballQSO”).ReceiverFundamentalsAradioreceiverconvertsradiowavesintotheoriginalmessagessentbyadistanttransmitter.Table4-3breaksdownthe40-meterbandaccordingtolicenseclasssuballocationsandmodeusagerestrictions.Solid-stateequipmentcommonlyoperatesfrom6voltsto12voltsDC.FIGURE5-2Youcanputastripofwoodatthebaseofanup-and-downslidingwindowandrunfeedlinesandgroundwiresthroughit.Ofcourse,aswithmosthamantennas,youshouldstringyourantennaupashighasyoucan.49MetersInthe49-meterband(5.900MHzto6.200MHz),conditionsaremuchthesameastheyareat60meters,althoughyou’lloccasionallyseeaskipzoneform.Occasionally,you’llfindyourselfspellingoutcertainwordsbecauseconditionshavegrownsobadthattheotheroperatorhastrouble“copying”youonSSB.Ifyouhaveageneral-coverageshortwavecommunicationsreceiver,youcanlistenatprogressivelyhigherfrequenciesasthestormorstormsystemapproaches.Theresultingvibrationstravelthroughasetofresonantdiskstotheoutputtransducer.AnFSTVtransmittercomprisesacamera,anoscillator,anamplitudemodulator,andaseriesofamplifiersforthevideosignal.Useinsulatedwire.Youcandeterminethefront-to-backandfront-to-sideratiosfromsuchagraph.Fourcommonexamplesfollow.ThestationhadthecallsignWWVbackthen,asitdoestoday.FIGURE1-4Two-wayradiosmountedunderthedashboardofmyvehicle.Ifyoucangetyourantenna15metersabovetheground,it’llsitafullwavelengthupthere,andyou’llgetexcellentlow-angleradiationandreception.ForNerdsOnlyIfyouwanttoknowtheactualwavelengthrangesofalltheshortwavebroadcastbands,youcanusetheformulathatIquotedaboveoneachoneofthem,usingTable2-1asyourreference,andfindout!Forthoseofyouwhogetarushfromexactitude,youcansubstitute299.792inplaceof300intheformula.TherearefewerscanlinesinSSTVthanintheTVreceiver;theconverteradjustsforthisdifference,yieldingapicturealmostasdetailed(exceptforthelackofmotion)asaTVbroadcastsignalundergoodbandconditions.(Yes,theauthoritiescancatchyou.)IntheUnitedStates,severalclassesofhamradiolicensesexist,allofwhichareissuedbytheFederalCommunicationsCommission(FCC).That’saround1600or1700watts,assumingthatyoudon’tconnectanythingelsetothecircuit.Onlyonesignalmayexistatagiventime,audiblefromagivenlocation,onagivenchannel.Thistypeoftransmissionlineisoneoftheoldest,andmosteffective,waysofgettingpowerfromaradiotransmittertoanantenna,especiallyatfrequenciesbelow30MHz.It’sstillusedtodaybymanyAmateurRadiooperators.Alternatively,youcantunedowntothe27-MHzCitizensBandtoseeifyouhearanythingthere.So,forexample,asIrolldownaWyomingroadonsomecrispFebruaryafternoon,Imightfindalocalrepeaterand,ifnooneisusingitandIknowthesubaudibleaccesstonefrequency,saysimply“W1GVlistening.”CallingaStationIfyouhearsomeonesaythatthey’relisteningonarepeater,feelfreetocallthemandhaveacontact!Saythatstation’scallonce,thenyoursoncewithoutphonetics,andthenagainwithphonetics,justasyouwoulddoonSSBtoansweraCQ.Yourchoicewilldependlargelyonwhetheryougoforheavyorlightoperation.Ithasaroughlycircularshape,centeredatthetransmittingstation’ssurfacelocation,anditgrowsinradiusasthefrequencyincreases.Maketheelementsalittletoolongasyouassembletheantenna,andthencuttheelementsback,centimeterbycentimeter,usingadiagonalcutter,untilyourstanding-wave-ratio(SWR)meterindicatesminimumreflectedpowerat18.118MHz.AllocationsbyModeOnthe17-meterband,youmustrestrictyourworktodigitalmodesonly,includingRTTY,PSK,MFSK,data,andCW,below18.110MHz.Abovethatfrequency,youcanusephoneandimagingemissions.This“spectralspreading”limitsthemaximumdatatransferrate.RadioWavePropagationThemovementofradiowavesthroughspaceatthespeedoflightiscalledwavepropagation.Gibilisco,Stan,Beginner’sGuidetoReadingSchematics,3rded.Thosecontoursindicateenergycomponentsthatincreaseinfrequencyasthemotor“revsup”toitsoperatingspeedandmaintainconstantfrequenciesthereafter.715F).DetectionofAMAradioreceivercanextracttheinformationfromanAMsignalby“choppingoff”eitherthepositiveorthenegativepartofthecarrierwave(inotherwords,rectifyingit),andthenfilteringtheoutputwaveformjustenoughtosmoothouttheRFpulsations.Othersliketopracticetheiremergencycommunicationsskills,sothattheycanservethepublicduringcrises,suchashurricanes,wildfires,earthquakes,orfloods.Forexample,youshouldn’tnegotiatearealestatecontracton20-meterCW(oranyotherhamband).ASCIIIfyoudoseriousworkonRTTY,you’llfindBaudotratherprimitivebecauseyoucan’ttransmitandreceivelowercaseletters.Instead,Irelyonamanualtunerwithlarge,discrete,ruggedinternalinductorsandcapacitors,eventhoughit’slessconvenient.Sendatthesamespeedastheotherstation,ormaybealittleslower.Inotherwords,thefrequencyofasignalvariesininverseproportiontoitswavelength.TipSlopedetectiondoesnotprovideanoptimummethodofdetectingFMorPMsignals.RadiohamsuseMFSK16moreoften.1-13,theoscillatoritselfwouldbeasocalledColpittscircuit,whichusesasplitcapacitanceandasimpleinductance.Otherlicenseclasseshaveprivilegesasfollows:•AdvancedClasslicenseescanusetherangesfrom7.025MHzto7.125MHzfordigitaloperation,and7.125MHzto7.300MHzforphoneandimagingcommunications.They’repassivecomponents,soyoudon’tgetanyamplification.Forthisreason,front-enddesigngrowsinimportanceasthefrequencyrisesthroughtheVHF,UHF,andmicrowavepartsoftheradiospectrum.IfaCWtransmitterproducesacarrierthatchangesfrequencyslightlyatthestartofeachcodeelement,addaCfor“chirp,”forexample“RST579C.”Ifasignalisamplitudemodulatedbyanaudiotonelikeamusicalnote,you’llhavetouseplainlanguagetoinformtheotheroperator.Theoutputtransducerconvertsthevibrationsbackintoanelectricalsignal.Agroundrodbyitselfwon’tsufficeunlessyouliveinasaltflatorswampwhereitrainsoften!YoucanenhancetheRFperformanceofyourgroundsystembyburyingquarter-wavelengthradialwiresaboutafoot(30centimeters)underthesurfaceofyouryard.Arrangethetwowiressothattheyrunindifferentdirectionsfromthephoneplug.TheFCCeliminatedthatrequirementaftercountriesthroughouttheworldagreedthat“thecode”nolongerrepresentedanessentialcommunicationsskill.Thefirstthingyou’llwanttodoistomakethereceivingprogramrecognizethesignalboundariesattheupperandlowerfrequencylimits.Hamssometimesusesmallloopsforradiodirectionfinding(RDF)atfrequenciesuptoabout20MHz,andalsoforreducinginterferencecausedbyhuman-madenoiseorstronglocalsignals.Inthenon-CWdigitalmodes,everytransmissionneedsacontinuouscarrier;nogapsexist.Acircularwaveguideshouldmeasureatleast0.6wavelengthindiameter,andpreferably0.7wavelengthormore.Youcanadjustthefontstyle,fontsize,fontcolor,andtextbackgroundcolor,aswellastheextenttowhichthetextfillsthescreen.Thefrontend,likeapreamplifier,mustremainaslinearaspossible.Butonceinawhilethatconveniencecanturnintoaproblem,especiallyundermarginalconditions,suchasQRM(interferencefromotherstations),QRN(radionoisesuchassferics),andQSB(signalfading).Areceivercaninterceptthesignalif,butonlyif,itsinstantaneousfrequencyvariesaccordingtothesamewaveform,overthesameband,atthesamerate,andinthesamephaseasthatofthetransmitter.Asimpleground-planeantennaisanexcellentoptionon17metersforthosewithaseriousDXinterestandamodestbudget.Thesolarfluxiscommonlymonitoredatawavelengthof10.7centimeters,whichcorrespondstoafrequencyof2800MHz.Atthisfrequency,whichisabout100timesthefrequencyofthehamradio10-meterband,theearth’satmospherehaslittleornoeffectonradiowaves,sotheenergyreachesthesurfaceatfullstrength.Anyoutdoorantennapresentsadangerwhenthunderstormsoccurinyourvicinity.Youcanthinkofthiseffectasthe“skipzoneexpandingtoinfinity.”It’smostlikelytohappenduringtimeswhenthesunspotcycleisat,ornear,itsminimum.AtB,asimplifiedblockdiagramofahamradiorepeater.Remembertheidentificationrequirements(atleastonceevery10minutes),keepyourtransmissionsdowntoreasonablelength(acoupleofminuteseachtime),andhavefun!EndingaQSOWhenyou’vehadenoughofaCWQSOorexternalcircumstancesforceyoutostop,wishtheotherstation“73”(Bestregards)ormaybe“88”(Loveandkisses)iftheotheroperatorisoftheoppositegenderandyouknowthatsheorhewon’tbeoffendedbysuchinformality.ExceptaspermittedundertheCopyrightActof1976andtherighttostoreandretrieveonecopyofthework,youmaynotdecompile,disassemble,reverseengineer,reproduce,modify,createderivativeworksbasedupon,transmit,distribute,disseminate,sell,publishorsublicensetheworkoranypartofitwithoutMcGraw-HillEducation’spriorconsent.Thisdataiseffectiveasof2014.NewYork:McGraw-Hill,2014.Thesepublicationscanhelpyougetlicensedsoyoucantransmitonthehamradiofrequencies.Ifyoucan’tgetamatchwithaparticularrandomwire,makeitalittlelongerifyoucan(orshorterifyoumust),andthenyoushouldbeabletomatchit.Pleasenotethatthisinformationwilllikelychangeinthecomingyears,soyoumightwanttodouble-checkthistableagainsttheARRLwebsiteorthelatesteditionofTheARRLHandbook.Exactcomponentvaluesmustbedeterminedbyexperimentation.Packetradiois,ineffect,computercommunicationsbywirelessmeans,andinhampacketradio,thatcommunicationscantakeplace(ifdesired)entirelyapartfromtheInternet.Excellentworldwideshortwavereceptioncanbehadatnightonthisband,especiallyinthewinteratlatitudesfarfromtheequator,becausethere’snotmuchthunderstormstaticandthedarknesshourslastalongtime.Althoughthegeometrylookssimpletothecasualobserver,adishantennamustbepreciselyshapedandalignedifyouwantittofunctionasintended.Youcanalwaystrytocaptureafrequency,sending“CQTEST”or“CQXXX”(whereXXXstandsforthecontestinquestion,suchas“SS”for“Sweepstakes”or“FD”for“FieldDay”),butunlessyouhaveapowerhousestation,youshouldexpecttomakemorecontactsifyouseekoutandsearchforstationssendingCQ,andthenrespondtothem.YoumightattendalargeAmateurRadioconventionandfindvintageradiosondisplaythere;youmightevenfindoneonsale.What’saDummyLoad?Assumingthatyou’veseenreadingsof0foralltheACvoltagesettings,repeatthetestswithyourmultimeter’sDCvoltagesettings,startingwiththehighestoneandworkingyourwaydowntothelowestone.Thedielectricalsokeepsthecenterconductorfromshortingouttotheshield.Touchthemeter’stwotestprobetipstoeachother.Thatmeansyouneedagoodgroundsystem.Palstardoesittherightway,withduplicatetunedcircuits,oneforeachconductorinthebalancedline.Afull-sizedipoleonthisbandmeasures79metersfromendtoend,andforoptimumperformance,itmustdangleatleast40metersabovetheground.TheUPShasfouroutletsintheback,twoofwhichgotopowerstripswithsixoutletseach,andtheothertwoofwhichremainempty.Theygetexposedtoalotmoreinterestingopportunitiesthanthefreebandersdo,andtheycandoitallwithinthescopeofthelaw!Inemergencies,CBradiocansavelives.StaySafe!Allengineerswhoworkwithantennasystems,particularlylargearraysorantennasinvolvingtheuseoflonglengthsofwire,placethemselvesinphysicalperil.Ifyourespondonanotherfrequency,evenaslightlydifferentone,theotheroperatorwillprobablymissthefactthatyou’recalling.Therestofthedevices,takentogether,drawabout7amps.•Fullbreak-inoperation,alsoknownasfullQSK,letsyouhearsignalsinbetweenthedotsanddashesofCWtransmissions,andinsomeradios,betweenwordsorsyllablesofspeechinSSB.Initssimplestform,awaveguideconsistsofahollowmetalpipehavingarectangularorcircularcrosssection.Advancedradioshaveprogrammablepassbands,andsomeletyouadjusttheshapefactor(describedunder“Specifications”)too!•Anautomaticnoiselimiterclipsnoise(QRN)peaks,whilenotaffectingthedesiredsignal.Iinviteyoutolookat,andhopefullysubscribeto,myYouTubechannel.Theradio-frequency(RF)spectrum,whichincludesradio,television,andmicrowaves,appearsexpandedinFig.PatienceEqualsPowerAttheriskofsoundingabitpatronizing,Iadviseyoutocreateasystemrestorepointforyourcomputerbeforeyoudownloadanyprogram,whetherit’sforhamradiooranythingelse.WhenyouwanttotestatransmitteratfullRFoutputbutyoudon’twantyoursignaltogoovertheair,youcanconnectadummyloadtoitsantennaoutputterminals.Fordarknesspaths,thesituationgetsmorevariable.Full-WaveBridgeCircuitYoucangetfull-waverectificationusingacircuitknownasafull-wavebridgerectifier.You’llreadmoreaboutthiscycleshortly.Nearlyallradiosthesedays,especiallytheonesdesignedforHFuse,havethefollowingfeatures:•Digitalfrequencydisplaysuseseven-segmentLEDorLCDmodulestogiveyouadirectnumericalreadoutofyourfrequency.FIGURE1-18CAtC,aratiodetectorcircuitfordemodulatingFMsignals.Thisdesignprovidessomepowergainoverahalf-wavedipole.YoucomparetheEMfieldstrengthinthefavoreddirectionwiththefieldstrengthatrightanglestothefavoreddirection.FIGURE5-5Simpletransmatch(antennatuner)circuits.Ahalf-wavedipolemeasuresabout10metersfromendtoendonthisband.2-10B.WhenAllElseFailsHamscanexchangepacketradiomessagesamongthemselvesandwiththeirowndigipeaters,radios,andcomputers,withoutinvolvingtheInternetatanypointwhatsoever.Ifthingsworkcorrectly,youshouldhaveareal-timepanoramicdisplayofEMenergyfromzerotoseveralthousandhertz.Engineersandscientistsdefineradiowavelengthsforfreespace(theearth’satmosphereorthevacuumofouterspace)unlesstheyspecifysomeothermedium,suchasawireorcable.Ifyouwantthistesttowork,you’llhavetofindareferenceoutletinyourhousethatyouknowhasagoodgroundatits“thirdhole.”FIGURE5-1Arrangementfordeterminingwhetherthe“thirdprong”ofanoutletactuallygoestoelectricalground.Thecomputercanalsostorethemessage.AllocationsbyLicenseClassIfyouhaveaGeneral,Advanced,orExtraClasslicense,youcanoperateoverthewhole10-meterbandusingtheemissionsasdescribedabove.Repeatsteps13through15foralltherestofthemeter’sresistancesettings,workingyourwaydownonesettingatatime,untilyougettothelowestone.HundredsofthousandsofpeoplehaveAmateurRadiolicensesintheUnitedStates.ChoosingaBandWhenyouwanttomakeDXcontactsonHF,you’llhavethebestluckifyouchoosetheoptimumband.Mostnon-CWdigitaltextmodeoperatorsdon’twanttogotothetroubletosetuptheirrigstoworkthatway.Inacontest,youmightfindthispointdifficulttoremember—untilsparksstarttoflyfromthebackofyourradio,oryourwholestationexplodesinyourface.Thegreaterthedegreeofnonlinearity,themoresusceptiblethecircuitbecomestothegenerationofmixingproductsandintermod.Keepitsbatteriesfresh.Asaformerradiofrequency(RF)engineerandantennaspecialist,thebestanswerIcangiveyouis“Idon’tknow.”Isuspect,however,thatifthe“dirt”indirtyelectricityhasadversehealtheffects,the“clean”part,whichproducesfarstrongerEMfields,probablydoesaswell.Theflareangleofthereflectingelementequalsapproximately90º.CosmicNoiseElectromagneticradiationfromouterspace,calledcosmicnoise,occursthroughouttheentireEMspectrum,fromtheVLFradiobandwherewavesmeasuretensofkilometerslongtotherealmofXraysandgammarayswherescientistsmeasurewavelengthsinnanometers(millionthsofamillimeter)andpicometers(thousandthsofananometer).Inadiscriminatorcircuit,yougetalinearrelationshipbetweentheinstantaneousdeviationoftheFM(whichcanresultindirectlyfromPM)andtheinstantaneousoutputamplitude.Today’sLicenseClassesIfyoudon’thaveahamradiolicensebutwanttogetintothishobby,you’llhaveachoiceofthreelicenselevelsor“classes.”MostpeoplestartwithasocalledTechnicianClasslicense,whichconveyslimitedprivileges,primarilyusingvoicemodes.Radiowavesoscillateatthousands,millions,orbillionsofhertz.Thispipmeansthatalloftheenergyinthewaveisconcentratedatonefrequency,knownasthefundamentalfrequency.Inaddition,thismethodofrectificationusestheentiresecondarywindingonbothhalvesofthewavecycle,soitmakesmoreefficientuseofthetransformerthanthecenter-tapcircuitdoes.Duringthedaytime,however,noantennawilllikelygetyoucontactsoverdistancesgreaterthan800kilometersorso.Unauthorizedpeoplefinditimpossibletoeavesdroponaspreadspectrumcommunicationslinkunlesstheygainaccesstothesequencingcode,alsoknownasthefrequency-spreadingfunction.Ifthere’samoderateamountofenergy,thelineturnsyellow.Withthisarrangement,youcanreceiveapacketfromtheradio,storeitinyourcomputer,andsendittosomeoneataspecifice-mailaddressontheInternetortoanotherhamwithapacket-equippedstation,eitherdirectlyorthroughoneormoredigipeaters.Whenmultipledirectorsexist,eachoneshouldbecutslightlyshorterthanitspredecessor.AnEMPhasnowell-definedfrequencyorwavelength;itexistsovertheentireEMspectrumincludingradiowavelengths,infrared,visiblelight,ultraviolet,Xrays,andgammarays.It’sagoodideatoletarepeaterdropoutaftertheotherstationendsatransmission,andthenstartyours.Capacitancesareinmicrofarads(µF).CQCQCQCQCQCQCQCQCQCQCQCQCQCQCQCQCQCQCQCQCQCQCQCQCQCQCQCQCQCQCQCQCQCQCQCQCQCQCQCQDEW1GVW1GVW1GVCQCQCQCQCQCQCQCQCQCQCQCQCQCQCQCQCQCQCQCQCQCQCQCQCQCQCQCQCQCQCQCQCQCQCQCQCQCQCQCQDEW1GVW1GVW1GVCQCQCQCQCQCQCQCQCQCQCQCQCQCQCQCQCQCQCQCQCQCQCQCQCQCQCQCQCQCQCQCQCQCQCQCQCQCQCQCQDEW1GVW1GVW1GVKKKYou’dneverlistentosuchabroadcastallthewaythroughfromaplainoldstatesidestationlikemine,wouldyou?HamscallthispracticeDXing,where“DX”standsfor“distance.”ButDXinginvolvesmorethanmaximizingthelengthofacommunicationspath,whichcan’texceed20,000kilometers(halftheearth’scircumference)inanycase.BythetimeyoureadanythingspecificthatImightquote,you’dhavegoodreasontosuspectthattheinformationhadalreadygrownobsolete!IfyouwanttogetintoSWLorAWLwithareasonablygoodradiorightaway,IrecommendthatyougotoyourlocalRadioShackstoreandshoparound.IfpartofthelinkgoesovertheHFbands,thelikelihoodoflongdelaysincreases.TipHamsdotheirSSTVoperatingintheSSBportionsoftheHFbands.Thistypeofpropagationcanproduce“reverb”onsignalsifthetwopathsdifferinlength(whichtheywill,unlessyouhappentoliveexactlyattheantipode,oroppositepointontheearth,fromthetransmittingstation).Thehighestsignallevelcorrespondstothedarkestshade(ideallyblack),andthelowestsignallevelcorrespondstothelightestshade(ideallywhite).Ifyou’reafreebanderrightnow,letmerecommendthatyougetahamradiolicenseandenjoyradiocommunicationstoitsfullest.BeCool!Onabusyband,suchas20metersonagoodday,alwaysaskifthefrequencyisinusebeforeyousendaCQ(arequestforanyonewhohearsyoutoanswer).Youcanreadthefrequenciesfromthegraduatedscaleatthetopofthescreen.So-called“bellwire”alsoworks.However,four-wirelineismoredifficulttoinstall,ishardertofindcommerciallymade,andcostsmorethantwo-wireline.Becausethepacketsthemselvesexistindigitalform,repeatersofthissorthavegottenthenicknamedigipeater.(ThetermYagicomesfromthenameofoneoftheoriginaldesignengineers.)Youcanconstructatwo-elementYagibyplacingadirectororreflectorparallelto,andataspecificdistanceawayfrom,asinglehalf-wavedrivenelement.Anyoneofthesethreetypesofdisplaywillworksatisfactorilyformostoperators.QSignalsforHamRadioAPPENDIXCTen-CodeSignalsforCBRadioTen-CodeSignalsforCBRadioAPPENDIXDTen-CodeSignalsforPoliceandEmergencyPersonnelTen-CodeSignalsforPoliceandEmergencyPersonnelSuggestedAdditionalReadingAmericanRadioRelayLeague,Inc.,TheARRLHandbookforRadioCommunications.Youmightusethebandexclusivelyforrepeatercommunicationsforyears,onlytogetararesurprisewhenatropoeventpopsupandyouhearsomeone800kilometersaway,cominginasiftheywerelocatedinyourneighborhood!TipWhenatropoeventoccurson2meters,thesignalscanactuatedistantrepeatersandproducechaosunlessthoserepeatersareclosedtoallsignalsexceptauthorizedones.FIGURE2-14Anoise-cancelingantennaschemethatworksespeciallywellatVLF.1-11.Evenifasmallloophasmanyturnsofwireandcontainsanoverallconductorlengthequaltoalargefractionofawavelengthormore,theradiationresistanceofapracticalantennaisafunctionofitsactualcircumferenceinspace,notthetotallengthofitsconductors.Areceiverwithabuilt-in“preamp”shouldallowyoutoswitchitoffwhenyoudon’tneedit.Atlowerfrequencies,efficientantennasaretoolargetocarryanduseatthesametime.Electronickeyerscomeintwomajorvarieties.ThereceivedsignalgoesintoacircuitcalledamixeralongwiththeoutputoftheLO,andthetwosignalsbeatagainsteachotherinthemixer.Inaddition,Ihavefoundthatthiscircuitdoesnotworkagainstsferics(thunderstorm“static”).TheHardwareToobservedirtyelectricityonyourcomputer,you’llneedan“antenna”thatcan“pickupthetrash.”Getanaudiocordatleast3meterslongwithaminitwo-wire(monaural)phoneplugononeendandspadelugsontheother.Whenpowergainoccursinthedirectionoftheparasiticelement,youcallthatelementadirector.OntheVHFbands,audiotonesareappliedtothemicrophoneinputofanAMorFMtransmitter,resultinginanemissionmodeknownasaudio-frequency-shiftkeying(AFSK).Becauseshortwavebroadcastingtransmittersgenerallyusemorepowerthanhamradiosdo,AmateurRadiooperatorssometimesfindcommunicationdifficultinthetop100kHzoftheir75-meterband.MostoftheCWoperationthatI’veheardtakesplacearound50.090MHz.You’lloccasionallyhearbeaconstationsonotherCWfrequencies.ButifIsay“S-TA-N,”theymightinsteadhear“F-E-A-M.”Thenthey’llbemoreconfusedthanever!Insituationsofthissort,Icanusephoneticsandsay,“MynameisStan:Sierra,Tango,Alpha,November.Ifyougodownlowenoughinfrequency,sayto100kHzorbelow,thewavelengthgetssolongthattheearthandtheionospherecombinetoactlikethesurfacesofatransmissionlineknownasawaveguide.Whenelectronsaccelerate(changespeed),theygenerateafluctuatingmagneticfield.6-8.PhaseModulationYoucanindirectlyobtainFMifyoumodulatethephaseofanoscillatorsignal.Youshouldalsomakesurethatyoudoeverythingaccordingtotherulesofyourowncountry.YoucanchewtheragonCW,RTTY,PSK31,MFSK,oranyothermode,butmostofthatactivityhappensinthelesscompetitiveportionsoftheSSBsubbands.Thisconductorshouldbeasshortasyoucanmanage.Sfericsarenotconfinedtoourplanet!AgreatdealofradionoiseisgeneratedbystormsintheatmosphereoftheplanetJupiter.Inaddition,thisbandactuallyrepresentsquitelowfrequenciesincontemporaryterms.eBookconversionbycodeMantraVersion1.0Alltrademarksaretrademarksoftheirrespectiveowners.CheckIt!IfyouexaminetheplotofFig.However,asphericalreflector,havingtheshapeofasectionofasphere,willworkokayinmostdishdesigns.IntheUnitedStates,thespeedis3600revolutionsperminute(3600r/min)or60revolutionspersecond(60r/s),resultinginanoutputfrequencyof60cyclespersecond(60Hz).Contactthemanufacturerandaskfordetailsaboutthemodelthatinterestsyou.Gotoadifferentcountry,preferablyanexoticone,andoperatefromthere!Thenyoucanhaveagreattimeworkingthousandsofstationsatapacelimitedonlybyyouroperatingskill.IntheAMTORcode,everylegitimatecharacterhasfourmarkbitsandthreespacebits.Theentirehelixshouldmeasureatleastafullwavelengthfromendtoendatthelowestoperatingfrequency.ButifIdokeepmyoperatingskillssharpanduseeverytrickIknow,Icansometimesbeat“bigguns”inadirectfaceoff!Whenthathappens,IrecalloneofthereasonswhyIgotintothishobby,andwhyIstickwithit.Inpulse-codemodulation(PCM),anyoftheabove-describedaspects—amplitude,width,orinterval—ofapulsetraincanbevaried.TipTodeterminethelengthofanRFgroundradialforaparticularfrequency,divide234bythenumberofmegahertztoobtainthelengthinfeet,ordivide71.3bythenumberofmegahertztoobtainthelengthinmeters.14.Othergalaxiesradiatenoise,butbecausethoseexternalgalaxiesliemuchfartherawayfromusthanthecenterofourowngalaxydoes,sophisticatedequipmentisneededtodetectthenoisefromthem.Ifyouhearonlyoneofthem,makesurethatyouknowwhichoneiscomingin!Youmightgetasurprisewhenyouthinkyou’rehearingWWVand,infact,it’sWWVH(orvice-versa).Unless,ofcourse,themeresightofyourantennaspookssomeone—unfortunatelyanotaltogetheruncommonoccurrence.Contestexchangesvaryincomplexity;somerequireonlyasignalreportandtheARRLsectioninwhichyoulive,whileothersrequirecontactnumbersorstationdataalongwiththesignalreportandyourlocationorsection.IFChainsAhighIF(atleastseveralmegahertz)worksbetterthanalowIFforimagerejection.DigiPan2.0wascreatedbyAmateurRadiooperators.Conditionstendtobealittlebetterinthefallandwinterbecausesferics,andatmosphericnoiseingeneral,arelessintensethantheyareinthespringandsummer.Noiseblankersaredesignedtoliterallyswitchthereceiveroffduringthesebriefspikes.•YoucanmakeaportableantennaexhibitgoodefficiencyatVHFandUHF,evenintheabsenceofasubstantialgroundsystem.•Noisefigureisaspecificationoftheperformanceofanamplifierorreceiver.Itcanbecircularorsquareinshape.EngineerssometimesexpressIF-chainselectivitybycomparingthebandwidthsfortwopower-attenuation(amplitude-reduction)values,usually−3dBand−30dB,alsocalled3dBdownand30dBdown.Signalstrengthreportscanvaryfromqualitativeexpressions,suchas“You’reboominginhere,thestrongestsignalI’veheardallday!”toquantitativereportsthatgivenumbersforreadability,strength,andqualityofsoundortone.Ifthedirectandreflectedwavesarriveatthereceivingantennawithequalstrengthbutsuchthatonewavelagsbehindtheotherby1/2cycle,youobserveadeadspot.TERMSOFUSEThisisacopyrightedworkandMcGraw-HillEducationanditslicensorsreserveallrightsinandtothework.IhadtolearntosendandreceiveMorsecodeatfivewordsperminute.AntennaEfficiencyYourarelyhavetothinkaboutantennaefficiencyinareceivingsystem,butinatransmitting-antennasystem,efficiencyrisestoparamountimportance!TheefficiencyexpressestheextenttowhichatransmittingantennaconvertstheappliedRFenergytoactualradiatedEMenergy.AtA,theground-planedesign.Thetransmitterhada“spot”settingthatactivatedallthestagesexcepttheRFdriverandfinalamplifier,soIcouldfindandsetmyexacttransmittingfrequencybylisteningtomyownsignalinthereceiver.Itcanincreasethelikelihoodof,orworsen,anypreexistingproblemswith“RFintheshack.”Inadditiontoallthat,ifyouconnectatransientsuppressorintothecircuit,itwon’tprotectanythingbecauseitwillhavenogroundto“workagainst.”Warning!Alwaysstrivetoprovideyourradioswithasteadylinevoltage.TheWorstNoiseofAll:EMPAnelectromagneticpulse(EMP)isasuddenburstofEMenergycausedbyasingle,abruptchangeinthespeedorpositionofagroupofchargedparticles.InatransmissionlineterminatedinapureresistancehavingavalueequaltothelineZo,nostandingwavesoccur,andthat’stheoptimalstateofaffairs.•Panoramicreceptionallowsyoutovisuallymonitoraspecifiedbandoffrequencies.Youcanconnectavariablecapacitorinseriesorparallelwiththeloopandadjustituntilitscapacitance,alongwiththeinherentinductanceoftheloop,producesresonanceatthedesiredreceivingfrequency.Alightportablestation,incontrast,lendsitselftouseasyouhaulitaround.WhenIgoton10meterCWanddialedmyDrakeT-4Xtransmitterdownto3wattsRFoutput,IsnaggedaNewZealandcontactonCWandgotasignalreportofS7(moderatelystrong).Muchmoreimportantistheabilityofareceivertotoleratestronginputsignalswithoutdevelopingnonlinearity.Forsignalreports,alwayssend“5NN”whichisCWshorthandfor“599,”eveniftheotherstationhasarottensignal.FIGURE2-5Atypicalsunspothasadiametergreaterthanthatoftheearth.ThedetonationofanatomicbombcreatesastrongEMP.•Switchthetransmitteron,andapplyalow-powersignaltothetransmatch.Theballmountcanwithstandthestressofgale-forcewindsthatcommonlytakeplaceinlocationsIliketofrequent,andalsofacilitatesconnectingthebraid(shield)ofthecoaxialcabletothevehicleframe.Besidesallthat,amobileantennatallerthan3meterswillraisepoliceandtroopers’eyebrows,ifnotprovokethemtopullyouoverandgiveyouaticketforcreatingahazardontheroad.Nowadays,mostastronomersbelievethatthenoiseoriginatedwiththefierybirthofouruniverse(aneventoftencalledtheBigBang),andcomestous“delayed”bybillionsofyears!Ifthey’reright,thenwhenwedetectandrecordthisnoise,weineffect“hear”theechoofCreation.Youcanalmostalwaysoperatesuchanantennaupto5percenteithersideofthecenterfrequencywithoutanyproblems,andsometimes6or7percent.Synchronizationsignalsaresentat1200Hzasshortburstslasting30millisecondsforverticalsynchronizationand5millisecondsforhorizontalsync.6-5,becauseQRPdoesn’tdemandmuchcurrent,andyouneedn’tworryaboutpossiblecontactresistanceintheconnection,whichcanproveproblematicorevendangerouswhenyouusethattypeofadapterwithaQROradio.That’swhy,inthesystemshownbyFigs.Connectthefarendofthewiretoagoodgroundroddrivenintothesoiltokeepelectrostaticchargesfrombuildinguponthewire.Youmightalsobaseyourdecisiononotherfactors,suchasthegeneralnoiseconditionsatyourlocation(14MHzhashorriblehumanmadenoiseatmyQTH,while10metershasalmostnone).Between21.200MHzand21.450MHz,hamsareallowedtotransmitwithphoneandimageemissions,subjecttolicenseclassrestrictions.OnthisbandandalltheHFbandsathigherfrequencies(shorterwavelengths),thelight/darkpropagationdichotomyreversesfromitslower-frequencystate.Doesthelampdimwhenyoukeyup?CoaxialCableCoaxialcableisdesignedforRFsignalsatfrequenciesfromVLFtoUHF.•Theappendixesshowtheschematicsymbolsthatelectronicshobbyists,radiohams,andengineersuseincircuitdiagrams,Qsignalsforhamradiooperators,andten-codesignalsusedbyCB,law-enforcement,andemergencypersonnel.Mims,ForrestM.,GettingStartedinElectronics.Tocalculate1/4electricalwavelengthinmetersfortubingorwire,divide71.3bythefrequencyinmegahertz.On70centimeters,thesplitisusually5.00MHz.Mostmoderntransceivershaveaprovisionforprogrammingthesplitfrequencyincaseyouencounterarepeaterthathasanonstandardsplit.TinleyPark,IL:GoodheartWilcoxCo.,2008.Otherlicenseclasseshaveprivilegesasfollows:•AdvancedClasshamscanusetherangesfrom3.525MHzto3.600MHzfordigitaloperation,and3.700MHzto4.000MHzforphoneandimagingcommunications.Agivenelectrolyticcapacitoralsohasacertainmaximumratedworkingvoltage.Figure1-17showsasimplepreamplifiercircuitthatcanuseeitherajunctionfield-effecttransistor(JFET)oraGaAsFET.Perhapsthe“coolest”modethathamsuseon2meters—prettymuchunknownonthelonger-wavelengthbands—isearth-moon-earth(moonbounce).Thesefactorsdegradetheimagequality.Figure7-3Aillustratesatypicalground-planeantenna.Asofthiswriting,youcanreadaboutitifyoupointyourWebbrowsertoIfyouwanttoseealotoftechnicaldetailsandyouhaveaninterestingettingontheairwithoneofthesemodes,hitthe“specifications”linkinthepageattheaboveURL.Ifyouhavedoubtsaboutyourvehicle’selectricalsystem,consultanautomechanicorthevehiclemanufacturer.Letthemtellyouallabouttheexampreparationprocess.ThosemodesincludeCW,RTTY,PSK,MFSK,anddatatransmission.Youincreasethesignalstrengthuntilthenoisevoltagedropsby20dBatthespeakerterminals.Theradio-frequencyinterference(RFI)issue,however,maymakeitimpracticaltorunthatmuchpower,asdescribedbelowunder“AdvantagesofQRPmobile.”Somevehicles’electricalsystemshavetroubleevenwithradiosthatconsumemoderateamountsofpower.Insynchronizeddigitalcommunications,alsocalledcoherentcommuniations,thereceiverandtransmitteroperateinlockstep.Emittedharmonicscancauseinterferencetootherservicesandoperations.Ifyouhavea117-voltinstallation,youcanaddapowerstripwithatransientsuppressor(sometimesmistakenlycalleda“surgeprotector”)anda15-ampbreaker.Sucheventsarerare,butifyoulistenonthisbandlongenough,you’llseesomecoolthingshappenhere.Let’sglanceatallthreeofthesehobbyradiospecialties,andthenwe’llreviewthebasicsofhowradioswork.ThedevelopersandusersofDigiPanandsimilarprogramshavecoinedthetermwaterfallforthedisplay,becauseofitsappearancewhensignalsexistatnumerousfrequencies.Alengthofcoaxialcablewitharolled-updipoleantennacanservethispurpose,butyou’llneedtotakeadvantageofexistingsupportssuchastreestogetanythingoutofit.THEWORKISPROVIDED“ASIS.”MCGRAW-HILLEDUCATIONANDITSLICENSORSMAKENOGUARANTEESORWARRANTIESASTOTHEACCURACY,ADEQUACYORCOMPLETENESSOFORRESULTSTOBEOBTAINEDFROMUSINGTHEWORK,INCLUDINGANYINFORMATIONTHATCANBEACCESSEDTHROUGHTHEWORKVIAHYPERLINKOROTHERWISE,ANDEXPRESSLYDISCLAIMANYWARRANTY,EXPRESSORIMPLIED,INCLUDINGBUTNOTLIMITEDTOIMPLIEDWARRANTIESOFMERCHANTABILITYORFITNESSFORAPARTICULARPURPOSE.TogetanSSTVsignal,youcaninputaudiodataintothemicrophonejackofanSSBtransmitter.Inagoodradioreceiver,anoiseblankerornoiselimitercanreducetheinterferencecausedbyprecipitationstatic.CharacteristicsThe20-meterAmateurRadiobandbehavesratherliketheshortwavebroadcast22-meterand19-meterbands.WhileALCisintendedonlytopreventovermodulation,speechcompressionemploysadditionalamplificationofthelow-levelcomponentsofavoiceinanefforttogetmore“bangforthebuck”outofthesignal.SmallBackupGeneratorsYoucanfindcompact,portablecombustiongeneratorsforuseinhomesandsmallbusinesses.Thephaseswitchallowsforinjectionofthenoisefromthenoiseantennaeither“rightsideup”or“upsidedown,”sothatyoucanmakesurethatitenterstherestofthecircuitinphaseoppositionwiththenoisefromthesignalantenna.•Flywheeltuning,inwhicharotatablefrequencycontrolsystemacquiresphysicalmomentumwhenyouturnit,givesthecontrolasubstantial“feel.”Youcanrapidlycarryoutseveralrevolutionsoftheknobwithasinglesharptwist;thedialkeepsongoingforasecondorsoafteryouletitgo.AnOldTimerRemembersWhenIattendedcollegeinthe1970s,fearsofaglobalnuclearholocausthadsubsidedenoughsothatmyparentsconsentedtomydrillingtwoholesthroughthatconcretewall.Themaximumlegalpoweroutputwassetat12wattspeak.Ifyouaren’tfamiliarwithschematicdiagramsliketheoneinFig.Evenbetter,tryaheadsetwithabuilt-inmicrophone,liketelephoneswitchboardoperatorsusedindayslonggoneby!AutomaticLevelControl(ALC)InanSSBtransmitter,automaticlevelcontrol(ALC)preventsexcessivemodulation(orovermodulation)whileallowingamplemicrophonegain.Theseunitsmightworkforhamsonastrictbudget,orwhodonothaveaccesstotherecommended234-voltACutilitypanelthatafull-powerlinearshouldhave.Forthisreason,packetcommunicationsisaformoftime-shiftingcommunications.Table8-1breaksdowntheRST(readability,strength,tone)signalreportingsystemthathamradiooperatorsuse.Figure5-16showshowignitionnoisewouldlookonanoscilloscopeconnectedintothesensitiveamplifiersofaradioreceiver.Andofcourse,everygoodfixedhamradioinstallationoughttohaveone!HowTheyWorkAsmallcombustiongeneratorprovides117voltsACintheUnitedStates(234voltsinmanyothercountries)at60Hz.LargergeneratorsintheUnitedStatesalsosupply234voltsACat60Hzforheavyappliances,suchaselectricrangesandlaundrymachines.Asyoumightguess,colorSSTVsignalsaremoresubjecttothewhimsofnoiseandinterferencethanaregrayscalesignals.APacket-EquippedHamStationFigure3-9Ashowsasimplehampacketradiostation.Infact,rareDXstationoperatorsoftenpreferthatyoucallalittleaboveorbelowtheirfrequency,notrightontopofthem.Iftheutilityandcommercialinfrastructuresgodown,packetradiowillstillworktosomeextentifyou’rewillingtouseHFforlong-haullinks.AllgoodPSKprogramshavewaterfalldisplays,atleastasanoption.Engineerscallthistechniqueenvelopedetection.TipAquarter-wavevertical“intheclear”andwithagoodgroundsystemcanprovidebetterDXperformance,insomecases,thanadipolecando.1-6.Atpowerlevelsover25wattsatsomefrequencies,strangemanifestationscanoccur,suchasspeedometerandtachometerreadinggyrationsonthelessseriousside,andfuelinjectionproblemsorignitionfailuresonthemoreseriousside.AllEMfieldshavetwoimportantproperties:thefrequencyandthewavelength.Thereflectingelementcanconsistofsheetmetal,ascreen,orawiremesh.4.Figure4-1showsthehamradiobandsbelow30MHz,onalinearscaleaccordingtofrequency.YoucanalsousethisschemetoreceiveFSKsignals.2-5.WhenyoulistentoaQSObetweentwostationsusingAMTOR,assumingthatyoucanhearthemboth,you’llrecognizeitrightawaybyits“tweet,tweet,tweet”sound.•YoucanalmostalwayscontactsomeoneonsomeHFbandfromanywhereintheworld.Peoplewhowanttousetherepeatermustknowthetonefrequencyandprogramtheirradiostoputitoutovertheair,ortherepeaterwon’taccepttheirsignals.ThemostfamiliarCBmode,calledClassD,operateson40channelsatfrequenciesaround27MHz(correspondingtoawavelengthof11meters).Audionotchfiltersaretunablefromatleast300Hzto3000Hz.Agoodnotchfilterhasanextremelynarrowbandstoprange,soyoucangetridofanunwantedcarriersignalwithminimaladverseeffectontherestoftheaudiorange.Italsohasanantennaoutput,ofcourse!Anold-fashionedanalogFSTVreceiver,whichcanbeusedwithoutmodificationtoreceivehamFSTVsignals,hasinputterminalswithanimpedanceofeither75ohmsunbalancedor300ohmsbalanced,atunablefrontend,anoscillatorandmixer,asetofIFamplifiers,avideodemodulator,anaudiodemodulatorandamplifierchain,acathode-raytube(CRT)or“picturetube”withassociatedperipheralcircuitry,andaspeakerorheadset.FIGURE6-10AnSWR-and-powermeterfacilitatespreciseadjustmentoftheportablestationantennafrequencyandalsogivesagoodindicationofactualtransmitteroutputpower.12.Otherlicenseclasseshaveprivilegesasfollows:•AdvancedClasslicenseescanusetherangesfrom21.025MHzto21.200MHzfordigitaloperation,and21.225MHzto21.450MHzforphoneandimagingcommunications.Theband“opensup”atnightallyearround,exceptwhenasolardisturbancedisruptsshortwavepropagationingeneral.Forsometime,thefunoutweighedmydesiretoremainalive.Foragivensignalpath,thepropagationusuallyimprovesasthefrequencyrisestowardtheMUF;atfrequenciesabovetheMUF,the“connection”deteriorates.AnOldTimerRemembersA40-meterdipoleantennafedwith50-ohmor75-ohmcoaxialcablewillworkon15meterswithoutmodification.Asaresult,anyonewithasubstantialcomputerworkstationwillendupwitha“tanglewiregarden”behindandundertheworkdesk.BalancedModulatorYoucansuppressthecarrierinanAMsignalusingabalancedmodulator,anamplitudemodulator/amplifierusingtwotransistors(or,intheoldendays,vacuumtubes)withtheinputsandoutputsconfiguredasshowninFig.Thatdevicewillgiveyousomeextrasensitivityandselectivityforbringingintheweakestsignalsandreducinginterferencefromthestrongestones.Shortwaveandallwavereceiverdesignsandfeatureskeepchanging,almostfromdaytoday.Thedisplayshowssignalamplitudeversusfrequencyaveragedoverashorttimeintervalastheuppergraph,andinstantaneousamplitudeversusfrequencyasthelowergraph.2-12A).Aselectivefiltercantheoreticallyeliminatethisproblem.YoucandetectFSKsignalsusingthesamemethodasCWdetection.Solarflarescanoccuratanytime,buttheytakeplacemostoftennearsunspotcyclepeaks.“Tanglewiregardens”canlookdangerous,asiftheywouldpresentahighfirerisk,buttheyneedn’tposeahazard.Confused?Whenyoudothatfortheso-called“41-meter”shortwavebroadcastband,yougetawavelengthrangeof39.5metersat7.600MHzupto41.7metersat7.200MHz.Thehamradiobandknownas“40meters”extendsfromanactualwavelengthof41.1metersat7.300MHzupto42.9metersat7.000MHz.Ifyouwanttoclaimtechnicalaccuracybasedonthecenterfrequenciesofeachband,youshouldprobablycallthehamband“42meters”andleavetheshortwavebroadcastbandat“41meters.”Butalas:Oncenamesgetassignedinthisbranchofscienceandengineering,theyusuallystaythatway.Relativelyfewpeoplecopythesignalsonmechanicalteleprintersnowadays;computersdothejobquietlyandwithoutmechanicalparts,inkcartridges,andpapertobreakdownorrunout.Forexample,onspecificweekendsinNovember,theSweepstakescontestfillseitherthedigitalorvoicepartsofmostHFbandswithaggressiveoperatorsusinghigh-poweredstationsandhugeantennas.Youcanmakeopen-wirelinefromcommonelectricalwire,suchasAmericanWireGauge(AWG)No.12orNo.14soft-drawncopper,spacedseveralinchesapart.AllocationsbyModeNomatterwhereyouoperateinthe30-meterband,youmustrestrictyourworktodigitalmodesonly,includingRTTY,PSK,MFSK,data,andofcourse,CW.Theradialsshouldconvergetoward,andconnectdirectlyto,agroundrodatthefeedpoint,wherethetransmissionlinemeetstheantennaradiator.Maximumradiation/responseoccursintheplaneoftheloop,andashallow,ratherbroadnullexistsalongtheaxis.Gotoandhitthelink“RFIKits”(orsomethingalongthoselines).Allofthesefactorsaffecttheionosphere.SlopeDetectionofFMandPMYoucanuseanAMreceivertodetectFMorPMbysettingthereceiverfrequencynear,butnotexactlyat,theunmodulated-carrierfrequency.Duringtheday,youcancommunicatereliablyatdistancesofuptoabout1600kilometers.Ingeneral,smallshapefactorsaremoredesirablethanlargeones,butsmallshapefactorsaremoredifficulttoattaininpractice.GototheARRLwebsiteatwww.arrl.organdlookforthelatesteditionofthatfinebook.Also,precautionsshouldbetakentoensurethattheaverage-powerincreasewillnotputtoomuchstrainonthefinalamplifierstageofthetransmitter.Thistypeofradiohasalightweightbatteryinsidethebox.Thetermlinearreferstothefactthattheamplifieroutputvariesindirectproportiontotheinput,sothatifyougraphtheoutputasafunctionoftheinput,yougetastraightline.PrecipitationNoisePrecipitationnoise,alsocalledprecipitationstatic,isradiointerferencecausedbyelectricallychargedwaterdropletsoricecrystalsastheystrikemetallicobjects,especiallyantennas.Allthreeoftheseprogramsareavailableonlineforfree,andtheyallworkonmostversionsoftheMicrosoftoperatingsystem(OS).TABLE1-2SymbolsintheInternationalMorseCodeforEnglishandOtherLanguagesThatUsetheSameAlphabetTipToday’scommunicationsdevicescanfunctionunderweak-signalconditionsthatwouldfrustrateahumanoperator.Irecallitsappearanceineverydetail.That’sstillthestandardBaudotspeedforhamradiousetoday.Lengthenandshortenitcentimeterbycentimeter,slidingoneofthesectionsoutoforintoitsneighbor,untilyougetminimumSWRatthedesiredfrequency.Thebesttypesarehalf-wavelengthaffairswithself-containedtuningnetworksatthebase.Nevertheless,itcanserveasanoptionwheneverythingelsefails.Atleastoneradio,theFT-897madebyYaesu,hasaself-containedrechargeablebatteryandcandoubleasaQRPmobiletransceiver.AswithPWM,atransmittermustworkhardertogeneratenegativePIMthantoproducepositivePIM.Thisfigure,expressedindecibels,tellsyouhowmuchacircuitdeviatesfromthetheoreticalideal.Mechanicalteleprinters,someofwhichremaininusetoday,employedeithercontinuous-feed“rollpaper”orcontinuous-feed“accordionfold”paper.NobindingdefinitionexistsforQRP,buthard-core,low-poweraficionadossaythatyoumustkeepyouroutputto5wattsorlesstoqualifyasafullmemberoftheQRPfraternity.Youcanexpressthingswithoutresortingtoabbreviationsorspecialsignalcodestosavetime.You’veseenground-planeantennasifyou’vespentmuchtimearoundfixedCB-radioinstallationsthatoperatenear27MHz,orifyou’vedonemuchham-radioactivityintheVHFbandsat50or144MHz.CoaxialAntennaYoucanextendtheradialsinaground-planeantennastraightdownward,andthenmergethemintoaquarter-wavelength-longcylinderorsleeveconcentricwiththecoaxial-cabletransmissionline.Itcantakeplaceatfrequenciesfarabove30MHzandoverdistancesofuptoabout2400kilometers.•YoucanalmostalwayscontactsomeoneonsomeHFbandfromanywhereintheworld,nomatterhowremoteyourlocation.AtA,pulse-amplitudemodulation(PAM);atB,pulse-widthmodulation(PWM),alsocalledpulse-durationmodulation(PDM);atC,pulse-intervalmodulation(PIM);atD,pulse-codemodulation(PCM).Inaddition,thesignalshouldnotdwellonanyfrequencylongenoughtocauseinterferencewithafixedsignalthathappenstolieonthatfrequency.Iobviouslyhadhigherpowersonmysidethatnight,oryouwouldnothavethisbookinyourhandsrightnow.Thereverberation,whichsoundsliketheechoyouhearwhenyoushoutinaroomwithbadacoustics,resultsfromthefactthatthelong-pathsignalarrivesafractionofasecondlaterthantheshort-pathsignal.Despiteitsinterestingnatureandtechnicaladvantages,youwon’thearAMTORverymuchontheairthesedays.Inagoodradio,amicrocomputerlimitstransmittingcapabilitytothehambandsonly.PonderThis!Inrecentyears,asourutilityandcommunicationsinfrastructureshavegrownmoresophisticated,they’vealsobecomemore“electromagneticallyfragile”andvulnerabletotheeffectsofgeomagneticstorms.Gibilisco,Stan,ElectronicsDemystified,2nded.Beforeverylong,Irealizedthattheseemissionscamefromhobbyradiooperatorsusingtransmittersintheirownhomes:radiohams!WhenIenteredthesixthgradeinthefallof1965,Istartedtakingahamradioclassinmyhometown,offeredbytheRochester(Minnesota)AmateurRadioClub.Newington,CT:ARRL,revisedannually.Someofthesemetersalsogiveyouanindicationofthestanding-waveratio(SWR)atthetransmitterantennaterminals.TutorialModeIrecommendPSK31forlearninghowtousenon-CWtextinyourcommunications.5-11,you’llnoticethatI’vemountedthepowerstripsonametalsheet.Onaquietwinterevening,you’llderivealotofenjoymentfromtuningyourradiotothisbandand“drillingdown”tofindthemostinterestingstations.Duringaspread-spectrumcontactbetweenagiventransmitterandreceiver,theoperatingfrequencycanfluctuateoverarangeofseveralkilohertz,megahertz,ortensofmegahertz.IfyouraisethefrequencyabovetheMULF,communicationwillnottakeplaceforawhile,butifyoukeepgoing,you’llestablishaworkingcircuitonceagain(betweenthesametwopoints)atafrequencycalledthelowestusablehighfrequency(LUHF).Bytheway,thisisn’ttheonlyweirdandexoticexperimentthatIdidbackinthose(relatively)carefreecollegedays.Acommerciallymanufacturedlinearusuallycomesfromthevendorasaself-containedunit,sometimeswithabuilt-inpowersupplyandsometimeswithanoutboardsupply.Inalatter-daycomparativesense,however,bothoftheseexpressionsconstitutemisnomers!Thewavesarelong,astheytravelthroughspace,comparedtothewavesinmostwirelesscommunicationsthesedays.FIGURE2-10AtA,theelectric(E)andmagnetic(M)linesoffluxaroundastraight,current-carryingwire.YoucangetanideaofthepropagationconditionsbetweenColorado,USAandyourQTHon60metersatanytimebytuningyourradioto5.000MHzandlisteningforthetimebroadcaststationWWV,operatedbytheNationalInstituteofStandardsandTechnology(NIST).Exceptionsoccur,sometimeswithspectacularopeningsonfrequenciesyouwouldn’tthinkcouldproduceanycontactsatall,letaloneforDX.However,mostnewhamsdon’tknowthattrick,soit’sgrownrare.Notmanyhamshavetherealestateforanythinglikethat.Ifyouextendthereceivingrangebelow3MHzdowntothelowestfrequenciesyoucangetaradiotobringin,andifyoucanalsoextendtherangeabove30MHzuptothehighestfrequenciesyoucanmanage,youcanthinkofthehobbyasallwavelistening(AWL).Thecarrierfrequenciesofthesignalsarespacedsothattheydon’toverlap.Thatcompanystillexists,andhasexpandedtheirlineofproducts.Ifthereceivingstationgivesthe“okay,”thenthetransmittingstationsendsthenextthreecharacters.Somehamsrunalotlesspowerthanthat!Theabbreviation“QRPp”standsforanRFpoweroutputof1wattorless.Ifyoudon’tdeliberatelyprogramthesplitin,theradiowilloperatewithadefaultsplitrepresentingthemostcommonlyusedvalueforthefrequencytowhichthereceiveristuned.Amplitudeappearsontheverticalscale;eachdivisionrepresents±3dBofchangeinsignalstrength(adoublingorhalvingofthesignalpower).Onceyou’veputyourselfthroughthisexerciseforafewhours,you’llknowifyou’re“cutout”forCW.ButAMTORdiffersfromthoseothermodesbecauseitinvolvescontinuousexchangesofdatainbothdirections,withfrequentswitchovers(onceortwicepersecond),oncecontacthasbeenestablished.Thenyoursystemwillbereadytoserveincaseofadisasterthatknocksouttheregularelectricalutility.They’vebeendoingitfordecades.Somehams,ratherthantalkingortextingorusingMorsecode(alsocalledCWforcontinuouswaves,eventhoughthewavesarebrokenupintodotsanddashes)ontheradio,prefertoexperimentwithelectroniccircuits,andsometimestheycomeupwithdesignsthatfindtheirwayintocommercialandmilitaryequipment.ThecurrentscausethepowerlinetoradiateEMfieldslikehugeradiotransmittingantennas!Power-linenoisesoundslikeabuzz,hiss,orroarwhenpickedupbyaradioreceiver.AnEMfieldcanhaveanyconceivablefrequency,rangingfromyearspercycletotrillionsofcyclespersecond(hertz).•Onthebandsat2metersandabove,theantennacanactuallyformpartoftheradiounit,aswithahandy-talkie.FIGURE1-2Here’saphotooftheantennaforthehamradiostationshowninFig.Mostoldershortwaveradioscan’tdoit.Onceyou’relicensed,ARRLpublicationsofferextensiveinformationandguidanceinvolvingeveryimaginablehamradiospeciality.Figure7-15Eshowstwinleadwithasolidwebofdielectricmaterial.Butrememberthathamradioisapubliccommunicationsmedium;nothing,technologicallyorlegally,canpreventsomeonewithagoodreceiverfromeavesdroppingonyouron-the-airrantings.HamssendandreceiveCWasasequenceofshortaudiotonescalleddotsandlongeraudiotonescalleddashes.Foronething,mystationisnothingclosetoanRFpowerhouse.Anybackupgenerator,ifpoorlydesigned,cancauseproblemsifyoutrytorunsensitiveelectronicequipmentfromit.Idon’trecommendthatyousendCQDX.That’snotalwaystrue.Mostlocalhamradioclubsholdregularexaminationsessions;iftheydon’t,oneoftheirmemberswillarrangetohaveavolunteeradministeryourtestbyappointment.Afteryou’vefinishedaCQ,waitforaminuteortwoandthentryagain.Neverrunyourgeneratorinagarage(evenanopenone)orapartiallyenclosedspaceofanykind.Theresultingvoltagesandcurrentsinradioantennas,telephonewires,andpowertransmissionlinescoulddamageordestroysensitiveelectroniccomponentsconnectedtothem.Ifyouthinkthatyourgovernmentthrowsalotofredtapeinyourway,waituntilyoudealwithaforeigncountry,especiallyonethat’snotentirelyfriendlytoyours!Youmighthavetogetaspeciallicense,andevenobtainpermissiontocarryyourequipmentintotheothercountry.Othersrequireaonetimepayment,usuallyamodestamount,afterafreetrial.Listenforacoupleofminutesandthen,ifyouhearnothing,askifthefrequencyisinusebeforeyoustartsendingCQs.InCW,youcansend“CQTEST,”andpeoplewillknowthatyou’relookingforQSOsinwhatevercontestprevailsatthetime.Sinceabout1970,repeaters,oftenfundedandmaintainedbylocalhamradioclubs,haverevolutionizedthenatureofcommunicationsonthesebands,especially144MHz(2meters)and440MHz(70centimeters).Likebending,ductingoccursmostlyatfrequenciesabove30MHz.TipRadiohamsoftencalltroposphericpropagationingeneral,withoutmentionofthespecificmode,“tropo.”AuroralPropagationWhenthesungetsunusuallyactive,theAuroraBorealis(“northernlights”)andtheAuroraAustralis(“southernlights”)canreturnradiowavestotheearth,facilitatingauroralpropagation.TipYoucanrunacoaxialcablerightnexttometalobjects,andthroughareaswherethereisalotofinterference,anditwillstillworkwell.CHAPTER6MobileandPortableHamStationsWhenlaypeoplethinkofAmateurRadio,theyusuallyimaginediversedesktop“rigs”andbigantenna“farms.”Whenmostfolksthinkofmobilestations,theyenvisionradiosofthesortfoundintaxicabsorpolicevehicles.TypingthetextonacomputerresemblesusingtheInternet.Bestofallistheso-calledJpole,whichcomprisesaquarter-wave,parallel-wirelinewithahalf-waveradiatorconnectedtooneofthetopendsoftheline.Engineerscallthisarrangementavoltage-doublerpowersupply.FIGURE6-5ADCpoweradapterplugforlow-currentmobile.TheARRLoperatingmanualcoverssomeofthese,butifyouwantthewholestorystraightfromthelawmakers’pens,youshouldgetacopyoftheFCCregulationsforradiohams.LinearAmplifierAlinearamplifieror“linear”isanRFpoweramplifierthatfaithfullyreproducesthemodulationenvelopeofanSSBorAMsignal.Eachofthedrivenelementscancompriseasingleradiatorasshownhere,ortheycanconsistofmorecomplexantennaswithdirectiveproperties.PreamplifierIfareceiverdoesn’thaveenoughsensitivitytosatisfyyou,youcanuseapreamplifierbetweentheantennaandtheradio.(Itcertainlyincludesme!)•IndoortransmittingantennascanexposeoperatingpersonneltoRFfieldenergy.Somethingaboutitstrikesmeasvulgar.Theonlywaytoobtainfullbreak-inoperationinPSK31,forexample,wouldinvolvesplit-bandduplex(inwhichonestationsendson,say,14.071MHzandlistenson21.071MHz,andtheotherstationsendson21.071MHzandlistenson14.071MHz).Someinnovations“takehold”andothersdon’t;evidentlyAMTORdidn’t.Ladderlineisalsorelativelyimmunetochangesincharacteristicimpedancethatcanoccurwhenitrains.StanhasbeenanactiveAmateurRadiooperatorsince1966,andoperatesfromhisstationW1GVintheBlackHillsofSouthDakota,USA.1-18B.TocheckthepropagationconditionsbetweenColorado,USAandyourlocationon30meters,tuneto10.000MHzandlistenforWWV.Thelowerleftdisplayscrollsdownwithtime;youshouldalignthebrightestpartsofthesignalwiththetwoverticallinesaboveit.Line-of-SightWavesRadiowavesalwaystravelinstraightlinesunlesssomethingmakesthembend,bounce,orturncorners.Infact,thetonenumberhasdevolvedinthepastseveraldecadestothepointofirrelevance.Let’slookatthebasicfunctionsandfeaturesofatypicaltransceiverofthesortyoucangetfrombrand-namevendors.•Prolonged,incessant“tuningup”ortestingonasinglefrequency.Itservesasitsownfilterbecausethecapacitors“smoothout”thepulsationsintheDCthatcomesoutofthediodes.Figure1-14Ashowsanamplitude-versus-timegraphofahypotheticalPAMsignal.Thecordontheleftgoestothefurnacefanandelectronics.ThisworkispublishedwiththeunderstandingthatMcGraw-HillEducationanditsauthorsaresupplyinginformationbutarenotattemptingtorenderengineeringorotherprofessionalservices.Engineersexpressandmeasurepowergainindecibels(dB).Howcopy?FIGURE1-10Spectraldisplayofahypotheticalsingle-sideband(SSB)voicecommunicationssignal,inthiscaselowersideband(LSB).•GeneralClasshamscanusetherangesfrom3.525MHzto3.600MHzfordigitaloperation,and3.800MHzto4.000MHzforphoneandimaging.Thistypeofantennameasuresroughly5meterstall,andtheradialsmeasurethesamelength.Youneverknowwhensomeonewillencounterarepeaterandurgentlyneedtouseit.Ifastation’stransmittergeneratessuchartifactssothatyouhearpoppingnoisesaboveandbelowthecarrierfrequency,addaKattheendofthesignalreport,forexample“RST579K.”Keyclicksresultfromtoo-fastattack(start)and/ordecay(end)periodsoncodeelements.TheTerminalNodeControllerATNCassemblespacketsthatare

composedon,andstoredby,thecomputer,andthenconvertsthepacketsintoaformsuitablefortransmissionbyradiousingdigital-to-analog(D/A)conversion.Whileafull-size80-and-75-meterantennaisn’tasimposingasits160metercounterpart,agooddipoleatareasonableheightstilltakesupalotofspace.Whenelectronsmove,theygenerateamagneticfield.MaximumUsableFrequencyImaginesomearbitrarymediumorhighfrequencyatwhichcommunicationispossiblebetweentwospecificpoints.Youcanmakecontactsallovertheworldnearthetimesofsunspotmaximawhenmost,orall,ofthepathliesonthesunlitsideoftheearth.Butthere’sadifferenceinthewaythesidebandsarearranged,frequency-wiseandbandwidth-wise.TipThischaptersummarizeshamradiooperatingbasicsformostmodesandinterests,butitonlyscratchesthesurface.InHamScope,thebuttonbearsthelabel“ReversePolarity.”Ifyouuseadifferentprogram,youmightseeitas“Rev”or“Reverse.”Justpokearounduntilyoufindit!You’llprobablyhavetoexerciseyourpowersofpatiencewhentuninginMFSK16signals.Youshouldnotusepowerstripswithtransientsuppressorsinconjunctionwithanyothercomponent,suchasaUPS,thatalsohasatransientsuppressor.11MetersEvidentlythisband,whichgoesfrom25.600MHzto26.100MHz,getslittleornouseforthepurposeofAMshortwavebroadcasting.TABLE2-1InternationalShortwaveRadioBroadcastBandsTechNoteAsthefrequencyofaradiowaverises,thewavelengthgrowsshorter.Thisfrequencywillliefarbelowtheusefulshortwavecommunicationsrangebetweenthesametwopoints.Butputtingacoilintheradiatingelementofanantennareducesitsefficiency(theratiooftheRFpowerthatactuallygoesoutintospacetotheRFpowerthatyourtransmitterputsinatthefeedpoint).InmemoryofJack,mentorandfriendAbouttheAuthorStanGibilisco,anelectronicsengineerandmathematician,hasauthoredmultipletitlesfortheMcGraw-HillDemystifiedandKnow-It-Allseries,alongwithnumerousothertechnicalbooksanddozensofmagazinearticles.Theupper1/3oftheband,atfrequenciesbetween7.200MHzand7.300MHz,harborshigh-poweredAMshortwavebroadcaststationsscatteredaroundtheglobe.Inordertogetthislicense,you’llneedtopassaratherdifficulttechnicalexamthathas50questions,37ofwhichyoumustanswercorrectly.AnOldTimerRemembersIrecallthetimewhenI,asaGeneralClasslicensee,lostalotofmyoperatingspace;asanew“General,”Ihadjustgottenalltheprivilegeshamradiohadtooffer.TryThis!Placeaplug-intypevacuumcleanernearyourEMpickupantenna.SomeNovices,Techs,andTechPlushamsfindthedesiretoget160-meterprivilegessufficientmotivationtoupgrade!DidYouKnow?Peopleoftenassumethatathree-wire117-voltutilityoutlethasagoodgroundatits“thirdhole”(thebottomhole,noteitheroftheverticalslots).•Chapter8detailshow(andhownot)tooperateahamradiostation,onceit’supandrunning,usingpopularvoiceanddigitalmodes.Youshouldalwaysgetareadingof0.Igotasubstantialmobileantennabasemount,aquarter-waveCBwhipchoppeddowntoresonateon28MHz,acollapsiblewhipfromMFJEnterprisesthatextendsfrom0.7meterto5meters,anActiveTuningAntennaSystem(ATAS)fromYaesu,a35-ampere-hour,deep-cyclemarinebatteryfromBatteriesPlus,andakeyerpaddlefromBencher.Ifyoucan’tfindanimpedancebridge,youcanadjustamanualtransmatchaccordingtothefollowingprocedure.Nevertheless,inpractice,weakFMsignalsthatfallfarbelowthelimiterthresholdareaffectedbystaticorimpulsenoisebecausethesignalsaren’tstrongenoughtomakethelimitingcircuits“kickin.”RepeatersInAmateurRadiopractice,repeatersareusedmostlyontheVHFandUHFbands.Youcanobtainenhancedripplesuppressionbyplacingalarge-valueinductorinserieswiththerectifieroutputalongwithalarge-valuecapacitorinparallel.Ifyouhaveaccesstoaglobe,youcanuseapieceofstringtofindtheshortandlonggeodesicsbetweenanypointsofyourchoice.Youdon’tneedmuchtransmitteroutputpowerto“worktheworld”evenwithamodestantenna,suchasadipoleorgroundplane,andthoseantennashavemanageabledimensions.Ifsuchservicesarerequired,theassistanceofanappropriateprofessionalshouldbesought.TheElayer,whichformsabout80kilometersabovethesurface,existsmainlyduringtheday,althoughnighttimeionizationsometimesoccurs.Whenductingtakesplaceonagrandscale,contactscansometimeshappenoverdistancesofuptoabout1500kilometers.TheEMfieldsfromground-mountedtransmittingantennasaremorelikelytointerferewithnearbyelectronicdevicesthanaretheEMfieldsfromantennasinstalledhighabovetheground.Ifyougraphthefunction,you’llgetFig.Whenthetransmittedsignalhasnomodulation,thepulsesemergeevenlyspacedwithrespecttotime.ItwillalsoworkonHFasa“littlesister”tomyQROtransceiver,theYaesuFT-857D.Thereceiverstayssynchronizedwiththetransmitterbymeansofanexternaltimestandard,suchasthedatafromWWV.CharacteristicsExperienced160-meteroperatorsknowitasawinternighttimeband.Itshouldhaveanoverallcircumferenceoflessthan0.1wavelength(that’sright,less!)atthehighestoperatingfrequency.Ifyouwanttodothat,you’llprobablyhavetomodifytheequipmenttoworkwithyourradio,achallengetothehamwholikestotinkerandperfectstationequipment.Onceinawhile,you’llhearstationsfrom1600kilometersto3200kilometersawayduringthedaytime,especiallyifthesunrestslowinthesky.UndernocircumstancesshallMcGraw-HillEducationand/oritslicensorsbeliableforanyindirect,incidental,special,punitive,consequentialorsimilardamagesthatresultfromtheuseoforinabilitytousethework,evenifanyofthemhasbeenadvisedofthepossibilityofsuchdamages.InthescenarioofFig.Thisfigurerepresentsradiationresistanceintheabsenceofreactance,andprovidesareasonableimpedancematchtomostcoaxial-cable-typetransmissionlines.IfthewirecarriesACorpulsatingDC,thefieldsfluctuate,producinganEMfieldthatemanatesfromthewire.Fortubingorlarge-diameterwire,vcanrangedowntoabout0.90(90%).Fordetailsonthelatestregulationsonthesematters,contacttheARRL.IusedaPalStarantennatunertomakemy10-meterwhipantennaworkfrom6metersallthewaydownto40meters(Fig.MostmoderntransceiverscanberemotelyoperatedbycomputereitherovertheradioorusingtheInternet.ThisphenomenonprovidesameansofmeasuringthesensitivityofanFMreceiver.Unlessyouinstallanextensivegroundradialsystemwithaquarter-waveverticalantenna,itwillhavepoorefficiencyunlesstheearth’ssurfaceinthevicinityformsanexcellentelectricalconductor(saltwater,forexample).Afterthat,you’llknowwhetherornottheotherstation’soperatorcanhearyou(orwantstotalkwithyou).Atypicallinearneeds70to100wattsofdrivepowertoproduceitsmaximumpoweroutput.7-7,boththeleft-handandright-handf/sratiosappeartoberoughly17dB.•Unidentifiedtransmissionsofanysort.Tomakemoonbouncecontacts,you’llneedatransmitterthatcanputoutalotofRFpower,preferablythelegallimitof1500wattsPEP,andworkinCWoroneofthesynchronizeddigitalmodes.Old-fashionedAMvoiceandFMvoiceareforbidden.Placethesignalantennainalocationfavorableforthereceptionofthestuffyouwanttohear,andlocatethenoiseantennasothatitwillreceiveasmuchdirtyelectricityaspossible(andrelativelylittleofthedesiredsignals).Ifyou’renotaCWoperatororyouarenewtohamradio,readtheprevioussectionandthenmonitorafewQSOsononeofthenon-CWdigitalmodestogetthegistofhowcontactsproceed.Full-WaveCenter-TapCircuitYoucantakeadvantageofbothhalvesoftheACcyclebymeansoffull-waverectification.Onceyou’vecarriedoutthesesteps,theupperpartofyourcomputerdisplayshouldshowajumbleoftextcharactersonawhitebackground.Inthefifthgrade,Igotamoresophisticated,commerciallymanufacturedshortwaveradioreceiver,theHallicraftersmodelSX-130.You’llobservethesameeffectifyousetyourradiotoreceiveLSBandyoutrytobringinaUSBsignal.ThePIVratingofadiodetellsyouthemaximuminstantaneousreversebiasvoltagethatitcanwithstand.Inawaveguide,thecharacteristicimpedancevariesconsiderablywiththefrequency,unlikeothertypesoflineinwhichtheZoremainsindependentofthefrequencyoverawiderange.ToneSquelchingInrecentyears,moreandmoreradioclubshaveequippedtheirrepeaterswithtonesquelching.Manyoperatorslikeflywheeltuning,butsomedonot.Ifyouhavealotofrealestateavailable(forexample,ifyouliveonafarmorranch),consideryourselfblessed!Puttheantennaupbetweenthetallestsupportsyoucanfind,suchasbigtrees.Withinafewyears,radiohamsdiscoveredthattheshortwavefrequenciescouldsupportlong-distancecommunicationsandbroadcastingonascalethatnoonehadimagined.FilteringMostDC-powereddevicesneedsomethingliketheDCthatwouldcomefromabattery,nottherough,pulsatingDCthatemergesfrommostsimplerectifiers.YoucangetafairRFgroundforend-fed,randomwiresfromtherebyrunningawireoutawindowandconnectingittoagroundrod.Separatesentencesorthoughtswithabreaksign(DAH-di-di-di-DAH)ratherthanaperiod(diDAH-di-DAH-di-DAH).Avariablecapacitor,inconjunctionwiththecoil,formsanRFtunedcircuit.Thesesidebandsaretheresultofsumanddifferencesignalsproducedbyamixingeffectthattakesplaceinthemodulatorcircuitbetweentheaudioandthecarrier.First,theoutputisdifficulttofilter;thatistosay,you’llfindithardtogetridofthepulsations(calledripple)intheDCthatcomesoutofthediode.Ahalf-wavedipolespans14metersfromendtoend;ifyoucutitfor10.125MHzattheexactcenteroftheband,you’llgetagoodimpedancematchto50-ohmor75ohmcoaxialcableovertheentirerange.EngineersinventedtheAmericanStandardCodeforInformationInterchange(ASCII,anacronympronounced“askee”)inthemiddleofthelastcenturytoaddressthisissue.It’spolarized,meaningthatyoumustconnectitinthecorrectdirection.It’sthesameeffectthatyougetifyourunanelectricspaceheateronthehigh-heatsetting.TipEvenwhenanantennasystemhasahighlossresistance,itcanstillbequiteefficientifyoudesignittoexhibitanextremelyhighradiationresistance.Allcontestsencourageyoutomakeasmanycontactsasyoucan,inasmanydifferentplacesasyoucan,withinasetperiodoftime,usually24to36hours.Hamsdon’thavetosharethisbandwithanyotherservices.ThenItookofftoWyomingonawintervacation,andhadmobileandportableCWQSOswithstationsallovertheworld.Despiteitsadvantages,somehamsusethephoneticalphabettoanextreme.You’llalsonoticethatinthesummertime,thunderstormsdon’tproduceasmuch“static”atthesefrequenciesastheydoonthelowerfrequencies.Youcanrunthewiredownintoyourhousethroughanopenwindow,slamthewindowshutonthewire,andthenconnecttheendofthewiretotheantennaterminalonthebackoftheradio.Table4-5breaksdownthe15-meterbandaccordingtolicenseclasssuballocationsandmodeusagerestrictions.Itcanalsobeusedinhigh-fidelityaudiosystemsandcomputerinstallationstointerconnectcomponents.MostFMcommunicationsreceiversusesquelchingsystems.TheonlyproblemthesedaysisfindinganAMTORsignaltocheckout!Themodeseemstohavefallenoutoffavor,perhapsbecauseoftheimmensesuccessandpopularityofPSK31,andincreasingtechnicalinterestinMFSKandWSJTmodes.Theexactfrequenciesoftheselimitsdependonatmosphericconditions,theseasonoftheyear,andthelocationsofthetransmittingandreceivingstation.Itis,ineffect,incrementaltuningthatworkswitheitherthereceiverorthetransmitter.MorseCodeTheMorsecodehasexistedlongerthananyothermethodofsendingandreceivingwirelessmessages.Frequency-ShiftKeyingYoucansenddigitaldatafaster,andwithfewererrors,thanMorsecodeallowsifyouusefrequency-shiftkeying(FSK).Figure3-2showsthekeyboardkeyerthatIacquiredaround1975,manufacturedbyacompanycalledHALCommunications.Areyouplanningtoworkinacontest,ortoworkDX?•Programmablememoryallowsyoutostorecertainfrequenciesandcallthemuplateratthepushofabutton,withouttheneedforchangingthebandswitchorVFOsetting.Youcanmakecontactsallovertheworldwhenmost,orall,ofthepathliesonthedaylightsideoftheplanetandconditionsaredecent.1-13.Withthesquelchopenandnosignal,thereceiveremitsahissbecauseofinternallygeneratednoise.I’veneverhadanytroublewithitafteroveradecadeofusealongwithmyIcomIC-746Protransceiver.B.)TipDuringaCWcontact,don’tsendpunctuation.WhichSidebandShouldYouUse?Youdon’twanttosetyourtransmitter’ssuppressedcarrierfrequencytocoincidewithachannelcenter.Thatthingstillworks!However,mosthamsusecomputerprogramsnowadaystogenerateCWiftheywanttosenditwithakeyboard.Youcansubstitutefour-wirelinefortwo-wirelineinalmostanyinstallation.Here’saPlug!Asofthiswriting,acompanycalledPalstarmakesanexcellentantennatunerdesignedwithatruebalancedoutput.Oneproblemwithtubularlineisthefactthatworms,insects,andspiderscangetinsidethecylinder,loweringtheZoespeciallyifthecreaturesspinwebs,whichholdcondensation.LowFERsIfyouhavealotofpatience,asensitiveLFreceiver,andawell-engineeredreceivingantennainagoodlocation,youmighthearsignalsfrompeoplewhoengageinahobbycalledLowFER(anacronymthatstandsforlowfrequencyexperimentalradio)inthelongwavefrequencyrangebetween160kHzand190kHz.Theactualwavelengthsgofrom1875metersdownto1579meters,andyou’llhearenthusiastsrefertothisslotofthespectrumingeneraltermsasthe1750-meterband.Ifyourstationhastogoabovegroundlevel,then,you’rebetteroffwithanantennawiththefeedpointlocatedagooddistanceawayfromyourstation.Agoodreceiverexhibitsdynamicrangeinexcessof100dB,whichtranslatestoasignalinputpowerratioof10,000,000,000to1!Acompetenttechniciancanconductexperimentstodeterminethedynamicrangeofanyreceiver.Youcalltheratioofthebandwidthat−30dBtothebandwidthat−3dBtheshapefactor.Theydoalotmorethanprovidefrequencystandardsandtellyouthetime!Asyouexploretheshortwaverealm,you’llhearstrangesignalsofallsorts:hissingandwhiningandroaringsignals,mostlyhigh-speeddigitaltransmissionsalongwithsomejammingsignals(yes,thatstuffstillhappens)whereonenationdoesn’tlikewhatanothernationhastosay.Themaximumradiation/responseoccursalongtheaxis,andminimumradiation/responseexistsintheplanecontainingtheloop.I’dhavedonebetterwithanopen-wirefeedline,butitwouldn’thaveworkedwithallthosebendsandnearbycopperpipes.FIGURE3-9AtA,ahamstationequippedforpacketradio.TheoutercircledepictstheRFfieldstrengthinthedirectionofthecenterofthemainlobe,andrepresents0dB(relativetothemainlobe,notadipole).Inaddition,ratherthanbotheringwithatruesignalreport,contestersandDXerswillsend“5NN”nomatterwhatthesignalsoundslike.7-6B.Manyofthesignalshaveamilitaryorigin.IndexPleasenotethatindexlinkspointtopagebeginningsfromtheprintedition.ThesetwoACwavesareindividuallyhalf-waverectified.Awell-engineeredlargeloopwillworkwellfortransmittingaswellasforreceiving.ForNerdsOnlyThetermlinearmeansthattheoutputenvelopehastheexactsameshapeastheinputenvelopedoes.Ifyourradiolacksanexternalantennaterminalandusesanattachedcollapsiblewhipantennainstead,strip3or4inchesofinsulationofftheendoftheantennawire,collapsethewhipallthewaydownexceptforaninchortwo,andwrapthebareconductoraroundtheendofthewhip.AdvantagesofQROPortableSomeportableoperatorsrunthefulllegalRFpoweroutputlimitof1500wattsPEPinheavyportablescenarios,suchastheannualARRLFieldDay,inwhichlargegasoline-orpropane-fueledgeneratorsarecommon.Atthehighestfrequencies,thezonecansometimesgrowtoan“infinite”radius,inthesensethatsignalsneverreturntotheearthatanydistance.AsyouincreasethefrequencyabovetheVLFband,thisschemegetslesseffectivebecausethenoiseimpulsesatthetwoantennasarenolongerexactlyinphasecoincidenceorphaseoppositionunlesstheantennasaresoclosetogetherthatthecircuitcancelsthedesiredsignalsaswellasthenoise.ConsiderThis!Irecommendthatyoubuildandprovideanemergencybackuppowersystemforyourrepeater!Youmightevenconsidertakingitentirelyoffthegridandrunningitwithsolarorwindpower,orahybridsystemthattakesadvantageofboth.Ifthelinesyncisnotright,thepicturewilltear,orgetrippeduphorizontallysothatitlookslike…well,likearippedupimage!MostoldanalogFSTVreceivershavecontrolsthatallowadjustmentoftheframeandlinesync,usuallycalled“verticalhold”and“horizontalhold.”Youhavetosettheminordertogetagooddisplay.•Qmultiplier—Inearlysuperheterodynereceivers,acircuitcalledaQmultiplierwasoccasionallyusedtoenhancetheselectivity.Inspread-spectrummode,theprobabilityofcatastrophicinterference,inwhichonestrongunwantedsignalcanobliteratethedesiredsignal,isnearzero.TechTidbitSpacetravelersofthefuturemighttakeadvantageofsurface-wavepropagationatlongwavelengthsonplanetsthathavenoionosphere,eventhoughwaveguidepropagationwon’tworkonsuchplanets.Inafilterthatusesacapacitorandaninductor,youcanplacethecapacitorontherectifiersideofthechoketoconstructacapacitor-inputfilter(Fig.Soineffect,PSKproducesthesameresultsasFSK.Butthingskeepchangingforradiohams!IrecommendthatyouperiodicallyvisittheARRLwebsiteforupdates,includingpossiblenewbandsoradjustmentstoexistingbands.Thistypeoflineiscalledtwinleadorribbon.CharacteristicsUndermostcircumstances,2-metercommunicationshappensinaline-ofsightmode,resemblingthebandsathigherfrequencies.Iftheradialsendupslightlylongerorshorterthantheradiatingelementwhenyou’vecompletedtheadjustmentprocess,thediscrepancywon’taffecttheperformanceoftheantennainrealterms,sodon’tworryaboutit.Amateur(Ham)RadioInmostcountries,peoplemustobtaingovernment-issuedlicensestosendmessagesbymeansofAmateurRadio.Above50MHz,mostvoicecommunicationsactivitytakesplacewithFM,oftenusingrepeatersthatreceiveandretransmitsignalstoextendtherangeofcommunications.TheACvoltagethatageneratorcanproducedependsonthestrengthofthemagnets,thenumberofturnsinthewirecoil,andthespeedofrotation.On/OffKeyingInhamradioMorsecode,theelementsaresometimescalleddotsanddashes,whereadotcomesoveryourspeakerorheadsetasashortaudiotoneandadashcomesthroughasalongertone(threetimeslonger,intheidealcase).AtthelongestwavelengthsintheLFband,andalsointhevery-low-frequency(VLF)bandbelow30kHz,communicationscircuitswillalmostalwaysfunctionworldwide,aslongasthetransmitterputsoutenoughRFpowerandthereceiverhasoptimumselectivityandnoiserejectioncapability.Asurgeofthissort“zapped”myfeed-pointtuneronasummerafternoonafewyearsago,eventhoughIhaddisconnectedandgroundedtheantenna.160MetersTheham160-meterbandextendsfrom1.800MHzto2.000MHz.ThatfrequencyrangeliesjustabovetheupperlimitofthestandardAMbroadcastband.Youcantuneapreselectorbymeansoftrackingwiththereceiver’smaintuningcontrol,butthistechniquerequirescarefuldesignandalignment.ItlookedandworkedgreatonthediningroomtableattheStargazerRanchguesthouse(Fig.Youmust“digaround”togetthisinformation;productreviews(especiallytheonesinQST,theofficialmagazineoftheARRL)canhelpyouout.Inotherwords,“20metersanddown”dobetter,generally,oversunlitpathsthantheydooverdarkpaths.HeadsUp!Nohammayuseatransmitterthatputsoutmorethan1500watts(or1.500kilowatts)PEPonanybandormode,ever.(Actuallythewavelengthcomescloserto17meters.)Conditionshereresemblethoseonthehambandcalled17metersat18.068MHzto18.168MHz,andviceversa.Anelectrolyticcapacitormakesagoodcomponentforthispurpose.Center-fed,half-wavelengthantennasdonot,asthey,ineffect,providetheirownRFgrounds.•SendingaCQdespiteotherhams’tellingyouthatthefrequencyisinuse.Whenrunningatfullspeed,aBaudotteleprinterproducedcharactersatarateequivalentto60wpm.IfyouhearSSBorCWsignalsinthispartoftheradiospectrum,they’reprobablycomingfromhamradiostations,especiallyifthey’rearound5.3MHzto5.4MHz.SkipTipsEngineersdefineskipasthetendencyforsignalstopassovercertaingeographicalareaswhentheypropagatebymeansoftheionosphere.Thetransmatchalsoattenuatesspuriousoutputsfromyourtransmitter,includingtheharmonics.Onceyou’vegotalongYagitunedjustright,youcangetwellover10dBdofforwardgainfromit.Butoccasionally,precipitationstaticoccursinradiocommunicationsinstallations.Figure2-14showsanexampleofacircuitthatIhaveusedtoaccomplishthisfeat.Butwhenhumanoperatorsareinvolved,theMorsecodehasprovenreliableingettingamessagethroughnoise(suchasatmospheric“static”)becausethehumanearcaneasilydistinguishbetweentherandomnatureofnoiseandtheorderlybeatofaMorsecodesignal.SpreadSpectrumInspread-spectrumcommunications,thetransmittervariesthemaincarrierfrequencyinacontrolledmanner,independentlyofthesignalmodulation.Intheextreme,theelectricutilitygridandtheInternetcanmalfunctionaswell.ItappearedatIfyoucan’tfinditbecausetheWebpagelocationhaschanged(acommonoccurrence;oh,thewondersoftheWeb!),tryasearchonthewordsequence:PSK31isadigitalcommunicationsmodewhichisintendedforlivekeyboard-to-keyboardconversationsProgramsThatDoPSKNumerousradiohamshavewrittenprogramsforreceivingandsendingPSKinitsvarious“flavors.”AlloftheseprogramscandecodeandencodeBPSK31.Thepowergainofawell-designed,two-elementYagiinitssinglefavoreddirectionisapproximately5dBd.AYagiwithonedirectorandonereflector,alongwiththedrivenelement,formsathree-elementYagi.ThePDFversiontalliesupwitha168-pagecountfromthe“top”tothe“bottom”!WhichRadio’sforYou?AnSSTVsignalneedsonly3kHzofspectrumspace,equivalenttoSSBinbandwidth,soSSTVispracticalonHF.•Recordthepositionsofthetransmatchcontrolsforfuturereference.IfyouwanttodosomecasualoperatingorDXingoranythingelsethatdoesnotinvolvecontests,andyouhappentohitoneofthemajorcontestweekends,youcangotoabandwherecontestingdoesn’thappen.WheretoFindItMostBPSK31enthusiastspopulateinformallyagreed-onfrequencyslotsinthedigital-modesegmentsoftheHFhambands.Evenifanasteroidweretostriketheearth,annihilatingeveryhumanbeingontheplanetexcepttwodedicatedradioamateurs,thenthosetwopeople,ifwell-equippedforemergencycommunications,couldtalktoeachother.Thiscommunicationsschemehasseveral“flavors”thatgobyarcanenamesincludingWSJT,JT65,JT6M,andFSK441.ThemajorityofcommerciallyavailableVHFradioscanrunatleast25watts.Believeitornot,withagoodantennasystemandexcellentpropagationconditions,youcanworkstationsontheothersideoftheplanetwithQRPp,especiallyonCW.Inaddition,you’llrarelyhaveangryneighborscomingtoyourdoordemandingthatyoustopinterferingwiththeircellphones,computers,televisionsets,refrigerators,toiletpaperdispensers,orwhatever.Inadisplayofthistype,thevoicedatashowsupassidebandsaboveandbelowthecarrierfrequency.ShortwaveRadioStartingover100yearsago,theradiopioneerscalledtherangeoffrequenciesfrom3to30megahertz(abbreviatedMHz)theshortwaveband.AgoodsourceforthesedevicesisacompanycalledMFJEnterprises.Theimpedanceatthefeedpointisanextremelyhigh,pureresistance.SomeDXstationsdislikegettingcallsexactlyontheirfrequency,soyoushouldn’tzerobeattheDXsignal.TheeffectivenessofthecircuitsshowninFigs.Youwon’thavetroublegettingahamradiooperator’slicenseifyouknowelectricityandelectronicsfundamentals.Ifitshowsanythingotherthan0,thenanACvoltageexistsbetweenthetwopoints,soyouroutletdoesnothaveagoodground.Inaddition,thetuning-aiddisplayforPSK31,knownasawaterfall,iseasyandintuitivetouse—andawholelotoffuntowatchand“tweak”!EarsversusEyesDespitethesimilaritiesinoperatingprocedure,afewtechnicaldifferencesprevailbetweennon-CWdigitalmodesandthegoodoldMorsecode,andthesedifferenceswillaffectthewayyouuseyourradioandassociatedperipheralequipment.Whenspeechcompressionisusedinatransmitter,thetransmitteroutputshouldbemonitoredwithaspectrumanalyzerorpanoramicreceivertoascertainthatsplatterdoesnottakeplace.60MetersIntherange4.750MHzto5.060MHz,you’llhearshortwavebroadcastsontheso-called60-meterband.Somesolid-webtypesoftwinleadhaveafoamed-polyethylenedielectricforreducedloss.BulletinBoardsInInternetpractice,abulletin-boardsystem(BBS)isa“forum”forstoredmessages,accessiblebymeansofacomputer.The160-meterbandmighthostafewspecializedtrafficnets,butotherwise,youwon’tfindthatbandofmuchuseonsummerdays.Wheresuchdesignationsappearinthisbook,theyhavebeenprintedwithinitialcaps.Largeronesburndieselfuel,propane,ormethane.Coronaesometimesoccurasaresultofhighvoltagescausedbystaticelectricityduringthunderstorms.(WhenIfirstgotmyhamradiolicenseinthe1960s,thisproblemwasmuchworsethanitistoday,andsometimes40meterswaspracticallyunusable.)Daytimecommunicationandreceptioncannormallybehadoverdistancesuptoabout1600kilometers.Theauxiliaryantennaactuallyworksbestifitdoesnotpickupanyofthedesiredsignals!I’veusedthattechniqueatVLF,anditcanworkamazinglywellwheneverythingelsefails.Ifyou’reaham,it’sallyours!CharacteristicsLike160meters,the80-and-75-meterbandworksbestatnight,andbetterinthefallandwinterthaninthespringandsummer.DetectionofCWandFSKIfyouwantareceivertodetectCWsignals,youmustinjectaconstantfrequency,unmodulatedcarrierafewhundredhertzaboveorbelowthesignalfrequency.ThepersonalcomputerisequippedwithInternetaccess(suchasacable,wireless,orsatellitemodem)aswellasaTNC,somessagescanbesentandreceivedbymeansofconventionalonlineservicesaswellaswiththetransceiver.Afewcancoverseveralbands.They’reallgreatbooks.Ireactedtothischangewithdismay,andthendecidedthatImightaswellupgradetoAdvancedandthentoExtraafewmonthsafterthat.InDXingorinacontest,it’llcompriseonlyasignalreportalongwithotheressentialinformation,suchasyourlocationandperhapssomecontestexchangedata.Ifyouuseatransmatchto“tuneout”reactance,youcanuseanyconvenientlengthoftransmissionline.Butthissituationcanbereversed(negativePWM).Andonceinawhilesomeonewillusephoneticsinawaythatmakesthemsoundalmostlid-like:“CQDeltaX-ray,”forexample,ratherthanthecorrect“CQDX,”whichmeans“CallinganyDXstationwhowantstohaveaQSOwithme.”TipYou’llfindalistofphoneticrepresentationsforall26lettersoftheEnglishalphabetinTable8-2.Thestagesbreakdownasfollows:FIGURE1-16Blockdiagramofasingle-conversionsuperheterodynereceiver.ACoolLittleProgramAsimplefreewareprogramcalledDigiPan,availableontheInternet,canprovideareal-time,movinggraphicaldisplayofEMfieldcomponentsatfrequenciesrangingfrom0Hz(thatis,DC)uptoaround5500Hz.Here’sthewebsite:www.digipan.netDigiPanshowsthefrequencyalongahorizontalaxis,whiletimeisportrayedasdownwardmovementallacrossthewholedisplay.IfyouspendalotoftimeworkingwithMFSK16,youmighteventuallyhavetheexperiencethatIreadaboutonablogsomewhere:Adisplaythatspontaneouslystartstoshowtextevenwhenallyoucanhearisnoise.Aslow-scansignalsendsamaximumofoneframeevery8seconds—240timesslower,allowingadramaticreductioninbandwidth.The120-Hzwaveisatthesecondharmonic,the180-Hzwaveisatthethirdharmonic,the240-Hzwaveisatthefourthharmonic,andsoon.Ifthe“thirdhole”inanoutletconnectstoawirethatisn’tgrounded,thatwirecanpickupstrayACbyelectromagneticinductionfromotherwiresinyourhouse,givingyouapotentiallylethalshock.Inanidealpacketnetwork,youcansendamessagetoanydestination,anywhereintheworld,andhaveconfidencethatthenetworkwillautomaticallygetittherewithinafewminutesor,atmost,afewhours.FIGURE1-15Blockdiagramofadirect-conversionreceiver.SomehamsuseTVribboninlow-powertransmittingapplicationsathighfrequencies(below30MHz)inplaceofopen-wireorladderline.ThetransmitterwasaDrakeT-4XandthereceiverwasaDrakeR-4A.•AdjustthetransmatchforminimumSWRasindicatedonareflectometerplacedbetweenthetransmitterandthetransmatch.(Youcould,ofcourse,justaswellremovetheLSBalongwiththecarrier,leavingonlytheUSB.)RadiohamsmakeextensiveuseofbothLSBandUSBontheirfrequencybands,especiallytheonesbelow30MHz.TheyfavorLSBatfrequenciesbelow10MHz,andUSBat10MHzandabove.Anincreaseintheinstantaneousdataamplitudemightcausepulsestobesentmoreoften,asisthecaseintheillustrationhere(positivePIM).SignalpathlosspresentsthemaindifficultyforanyonewhocontemplatesEMEcommunications.Alternatively,thetwoelementscanbedriveninphaseandspacedataseparationofonefullwavelength,asshowninFig.Withalittlestudy,agooddealofpractice,andafewyearsoftime,thedreammorphedintoreality!AndpeopleanswermysignalsnowwhenIsendCQ,theequivalentof“Calling!Calling!”,withaMorsecodekeyorthedigitalinterfaceofmymicroprocessor-controlledham“rig”inmybasement“hamshack.”Thefactthatafewwatts’worthofenergywavescansquirtfrommydeckmountedorvehicle-mountedantennaintotheatmosphere,thataminusculebitofthatenergycanlandinsomeoneelse’santennaontheothersideoftheworld,andthatwecancommunicatethiswayandcankeepincontactbymeansofthatenergyevenifeveryInternetserverontheplanetwentdown—well,thewholebusinessfascinatesmetothisday.Onceyou’vegottentheaudiofromyourradiointoyourcomputer,you’llneedtodownloadaprogram(ortwo,orthree)thatcandecodethesignalsinthedigitalmodeofinterest.Beware,especiallyifyouhaveasmallcar.Third,I’veconnectedadedicatedgroundwirefromthechassisoftheUPStoaknownelectricalground.InorderforanFSTVpicturetoappearnormal,thetransmitterandthereceivermustmaintainexactsynchronization.Youmightnoticeaslightimprovementindaytimepropagation,andaslightdeteriorationatnight,comparedwiththoseotherbands;inaddition,conditionsinthespringandsummerareusuallybetterthanthoseinthefallandwinter.Butyou’veprobablyfiguredthatoutalready,haven’tyou?Itprovidesunidirectionalradiationandresponse,withthefavoreddirectioncoincidentwiththeopeningofthehorn.Whenyouwanttodecodeasignal,youmoveapointer(whichlookslikeatall,skinnyhumanfigurebetweentwoverticallines)toitspip,andthenleft-clickyourmousetomakeabold,vertical,dashedlinemovethere.IrecallhearingWLSinChicagoonthatradioatnight,andmarvelingatthevastdistancesoverwhichradiowavescouldtraveloverfreespacetoreachme,inmybedroomwiththatearphoneclampedagainstmyheadinRochester,Minnesota!Myfascinationwithradiobeganbackthen.Thendrillholesinthewood,havingthecorrectdiametersforyourcablesandotherwires,andthreadthosecablesorwiresthroughtheholes(beforeyouinstallcableorwireconnectors,ofcourse).6-6,whichhasitsownbuilt-inSWRandpowermeter.Whileragchewsonrepeaterarenotunknown,theytakeplaceonlywhenarepeaterwouldlikelyseenouseotherwise;andtherag-chewersarealwaysreadytoallowbreakerstotakeoverwhentheyneedtherepeaterforsomethingimportant.IfyoueverseeanyDCvoltagebesides0betweenthetwopoints,thenyouknowthatyouroutletdoesnothaveagoodground.Theydo,however,eachhave15-ampcircuitbreakersforextraprotectionincaseofanequipmentshort.OnthefirstfullweekendinDecember,you’llencounterthe160-metercontest,andinJanuary,there’saDXcontestdownthere.Solarnoisecanposeaproblemwithmoonbounce,aswell.Theoutput,orsecondary,voltageofastep-downtransformerislowerthantheinput,orprimary,voltage.75MetersTheshortwavebandat3.900MHzto4.000MHzlieswithintheAmericanhamradio75-metervoiceband,sohamradiooperatorsmustsharethespectrumwiththesestations.Asthesignalgetsstronger,thelevelofthenoisecontinuestodecrease.CQ,CQ,CQ,thisisW1GV.Eitherway,allthepulsesalllastforthesamelengthoftime.Nomatterhowmuchofalidsomeonemightbe,don’tlethisorherbadmannersturnyouintoalid,too.Ifyou’reaNovice,Tech,orTechPlusoperator,you’llhavetoupgradeatleasttoGeneralbeforeyoucantransmithere.IdidallthisonCWwith50wattsoutput,usingtheYaesuFT-857Dpoweredbya35-ampere-hour,deep-cyclemarinebattery.TipIfyou“loaddown”a117-voltcircuitsothatitmustprovideitsfullratedcurrent(orclosetoit),you’llnoticethatthevoltagedropswhenyoukeyupalinear.HamsdomostFMoperationontheirVHFandUHFbandsinthenarrowbandmode.YoucansuppressoneofthesidebandsinasubsequentcircuitwiththeadditionofabandpassfiltertoobtainanSSBsignal.Thatway,you’llknowifgeneratorexhaust“blows”intothehouse,asituationthatcanarisewithamazingease,asIdiscoveredwhenIranitinthewoodshedundermydiningroom.TheAMTORcodehassevenbitsforatotalof128(27)possiblecombinations,asopposedtothe32(25)possiblecombinationsinthefive-bitBaudotcode.Byobservingsomesimplesafetyguidelines,youcanminimize(butnotcompletelyeliminate)therisk.You’llappreciatethisfactwhenyouspendafewdaysataQTHwherecellphones,theInternet,andrepeatersaren’tavailable.ShortwavelistenersoftengetinterestedenoughincommunicationstoobtainAmateurRadiolicenses,sotheycanengageinend-to-end-wirelessconversationswithotherradiooperatorsonaglobalscale,amodethatrequiresnointerveninginfrastructureotherthantheearth’supperatmosphere.1-16),alongwithextraaudioamplifierssothatthesoundcoulddrivealoudspeaker.IfyouwanttotalkaboutfootballwithaGreenBayPackerfan(suchasmyself),youmightgetrazzedifyourootforsomeoneelse,butyouwon’tsparkWorldWarIII.(ThisstripdoesnothaveatransientsuppressorbecausetheUPS,whichalsogoestoalltheelectronicsthatIwanttoprovidewithbackuppower,hasabuilt-intransientsuppressor.)Whenapowerfailureoccurs,IunplugtheUPSfromtheutilitymainsandplugitintothegenerator,physicallyremovingtheplugfromtheutilityoutletbeforeputtingitintothegeneratoroutlet.Anothertropospheric-propagationmodeiscalledtroposphericscatterortroposcatter.TheSX-130didnothaveaninternalcalibrator,soIhadtoguessattheexactfrequencytowhichtheradiowasset.TheRFfieldtravelsdownthepipe,providedthatthewavelengthisshortenough.Ifyoumustusea“sunfilter,”useonethatblocksultravioletrays.Althoughpropagationvariesfrombandtoband,conditionsatthetopofanygivenbandarenearlyalwaysthesameasconditionsatthebottomofthesameband.Thisformulaworksbasedontheassumptionthatv=0.95,atypicalfigureforcopperwireofreasonablediameter.Eachlinecontainsshadesofbrightnessinagrayscalesystem,andshadesofbrightnessandhueinacolorsystem.Insomeradios,thesquelchdoesnotopenunlessanincomingsignalhascertainpredeterminedcharacteristics.Somecircuitsneedhighvoltage.Ifyou’reinterestedingettinginvolvedinemergencypreparednessusingAmateurRadio,andassumingthatyouhavealicense,here’swhatyoushoulddotostart:•Equipyourstationsothatitcanrunfromemergencypowerforalongtime.TheWholeStoryAtthetimeofthiswriting,Ifoundawebsitethatprovidestablesthatyoucandownload,showingallofthefrequencyallocationsintheentireradiospectrum.Infact,somehamradiogroupsorclubshavesetuptheirownradionetworks,andquiteafewhave“patched”intotheInternetaswell.Forexample:W7***,thisisW1GV.Mostradioshavereceiverincrementaltuning(RIT)intendedforthissortofsituation.•TheHFbands,especiallytheonesat14MHzandup,offergreatpotentialformakingDXcontactsfromplacesfarremovedfromthemadnessofcivilization.FIGURE7-11Dishantennaswithconventionalfeed(A)andCassegrainfeed(B).Whenstandingwavesdoexist,you’llgetanonuniformdistributionofRFcurrentandRFvoltageasyoumovealongtheline.TipIfyoucantypefast,andifyouwantyourPSK31signaltocomeoutatthehighestpossiblespeed,sendeverythinginlowercase.•MostVHFandUHFradiosaresimpleandcompact,don’tgobbleupalotofpower,andlendthemselvestoeasyoperation.MosthamRTTYprogramsarewrittenforMicrosoftoperatingsystems,notablythevenerableoldWindows98orWindowsXP,soyou’llfaceachallengeifyou’reaMacuser.Youmustconnectyourantennatoagoodground,preferablyalongcopperrod(2metersormore)drivenintogoodsoilandplacedatleast10or15metersfromyourhouse,wheneveryouaren’tusingtheradio.Withalittletestingandtweaking,maybeyoucanmakeitworktoo.MostcommercialunitsaredesignedtoworkwithAM,buttheycanbeconvertedtoworkwithFM.Youneverhavetoworryabouttheriskofoverheatingorarcinginyourtransmissionlineortunercomponents,nomatterhowhightheSWRgets.Writeyourtextoneveryotherline.Forserioususersofthismode,Morsecodeintheformofsimpleon/offkeyingoffersbyfarthebestoption.AnOldTimerRemembersWhenIwasafoolishteenagehaminthelate1960s,IlovedtheARRLFieldDaycontestthattookplaceonthelastfullweekendinJune.Eachlocalnodeservesseveralstationsinitsimmediatevicinitybymeansofshort-rangelinksontheamateurVHF,UHF,andmicrowavebands.•Inanemergency,you’llhavethebestchanceofgettinghelpintheleastamountoftimeifyourunthehighestRFpoweroutputthatyou(andyourbattery,ifyouuseabattery)canmanage.ThecircuitatEemploysasingle-transistoramplifier,providingsomegainiftheincomingsignalhasbeensufficientlyamplifiedbythefrontendbeforeitarrivesatthedetectorinput.Youcanrenewyourlicenseatthesamelevelwithouttakingthetestoveragain.Theactualmaximaandminimavaryfromcycletocycle.Asforlearningtouseit,youcandoasIdid:FollowtheCOEISASWHparadigm(clickoneverythinginsightandseewhathappens).Ineverdothat.You’llstillfindsuchcircuitsinsomevintageradios,alongwithceramicandmechanicalfilters.Theymustalsobeabletobringinstrongsignalswithoutdesensitization(losinggain),aphenomenonalsoknownasoverloading.Forexample,ifyoukeephearing“W1GV”overandoveratintervalsofaboutaminute,youcanhaveconfidencethatI’mcallingaDXstationinapileup,especiallyifyoucanalsohearnumerousotherstationssendingtheirowncallsignsatintervalsofaboutaminute.Whentheradiationresistanceiscomparableto,orsmallerthan,thelossresistance,atransmittingantennabehavesinaninefficientmanner.Thecomputercanservetonetworkwithotherhamswhoowncomputers,anditfunctionsasaterminalforthetransceivers.AdvancedFeaturesSophisticatedradioshavecapabilitiesthatcanhelpyouwithcontesting,traffichandling,specializedmodes,andDXing(seekingoutcontactswithstationsinexoticlocations).Youmustmakesurethatyourpreamplifierremainslinearinthepresenceofstronginputsignals.However,duringameteorshower,multipletrailscanproducealmostcontinuousionizationforaperiodofhours.Belowabout6or8kHz,noisefromtheutilitylinesmadereceptionimpossible,butIdidnotexpectanysignalstoexistthereanyway,sincetheFCChadmadenoformalallocationsbelow9kHz.ThetrickdidnotworkintheSSBmodebecausethefiltersintheRFstagesoftheT-4Xcutoffabove3kHz.Nosuchfiltersexisted,evidently,intheAMmode.IusethespectrumdisplayinHamScopebecauseitoffersaclearerindication(tomyeyes,anyhow)thanthewaterfalldoesinthatparticularprogram.Intheearly1900s,mostwirelesscommunicationandbroadcastingtookplaceatfrequenciesbelow1.5MHz(wavelengthsofmorethan200meters).InamateurHFactivity,mosthamsusethelowersideband(LSB)onthebandsbelow10MHz,andtheuppersideband(USB)onthebandsabove10MHz.There’snotechnicaladvantagetousingeithersidebandonanyfrequency;thesestandardshaveevolvedasamatterofconvention.HornAhornantennalookslikeasquared-offtrumpet.Stillothersliketoventureintothewildernessandtalktopeoplethousandsofkilometersawaywhilesittingoutdoorsunderthestars.AnAMTORCQsoundsjustaboutthesame,whenitcomesfromyourloudspeakerorheadset,asanordinaryRTTYsignaldoes.Ifyouraudioprogramhasa“noisereduction”feature,turnitoff.Whenyoulistentosignalsinthisband,youcantellthedifferencebetweenhamradiostationsandshortwavebroadcaststations.OtherwisethesignalwillsounddistortedwhenyoulistentoitinareceiverdesignedforordinaryFM.FIGURE1-1Myhamradiostationincludesatransceiver,anInternet-readycomputer,aninterfacefordigitalcommunications,apoweroutputandantennatestingmeter,anaudioamplifierwithfourspeakers(oneshownhere,atextremeright)andtwodisplays,oneofwhichisa46-inchhigh-definitiontelevisionset.Youcanadjustthecolorstosuityourtaste.Figure3-3showsthefullMMTTYdisplaywiththeprograminaction.Inthissituation,theradiationresistanceRRofthewireisafunctionofitsheightinwavelengths.Inthisscheme,therepeater’sreceiverincorporatesasilencingcircuitthatstaysclosedunlessanincomingsignalismodulatedwithatoneofacertainfrequencyand/orduration.Whendesigningapowersupply,youmustusediodeswithanIoratingofatleast1.5timestheexpectedaverageDCforwardcurrent.AnOldTimerRemembersInMarch2014,stilltechnically(andweatherwise)wintertime,ItestedmymobileCWradioon10metersandworkedDXallovertheworldfromWyomingandMontana.Whenyouwanttotransmit,youpressandholddownabutton,usuallyamomentary-contactswitchonthesideofthemicrophone.OperatinginNon-CWTextModesYou’llhaveaneasytimeoperatinginthenon-CWtextmodes(RTTY,PSK31,MFSK,AMTOR,andthelike)ifyouhaveCWexperience.HamsoftencombineUHFantennasinarrayscalledbays—forexample,fourhelicalantennasatthecornersofasquare,orevennineofthematthepointsofa“Tic-Tac-Toe”matrix!Whenfedinphaseandcarefullyaligned,suchbayscanhavedirectionalityandgaincomparabletoadish.Invoicemodes,youcanleavethetonenumberout,eventhough,arguably,itwouldprovemoreusefulonthosemodesthanonCW!Soyoumightsay,inCW,“RST579”butinSSByouwouldsay“You’re5by7.”TABLE8-1TheRST(Readability,Strength,Tone)SystemforSignalReportingDespitethelackofatonenumberinsignalreportsforthevoicemodes,youshouldtelltheotheroperatorifhisorhervoiceisdistorted,tinny,muffled,orotherwisemutilated.Thatway,peoplecasuallytuningthroughthebandwillnotlikelyunderstandyourtransmissionsunlesstheydeliberatelyswitchsidebandsinordertopayattentiontoyou.Thebetterthequietingsensitivity,thelesssignalittakestoactuatethesquelchatthethreshold.TipHamradioisanelectronics-intensiveand,increasingly,computerintensivehobby.SingleSidebandAsmentionedearlier,inanAMsignalwith100%modulation,thecarrierwaveconsumes2/3ofthesignalpower,andthesidebandsexistasmirrorimageduplicatesthat,combined,takeadvantageofonly1/3ofthesignalpower.TubularlineshaveZovaluessimilartothoseofladderlines.Half-WaveAntennasYoucancalculatethephysicalspanofanEMfield’shalfwavelengthinfreespaceusingtheformulaLm=150/fowhereLmrepresentsthestraight-linedistanceinmeters,andforepresentsthefrequencyinmegahertz.OverviewFixed-stationradioshavepowersuppliesthatletthemworkdirectlyfromthe117-voltor234-voltAChouseholdutilitymains.FIGURE2-3StationXtransmitsasignalthatreachestheionosphere,whichbendsbackthewavesenoughtoreachstationZbutnotenoughtoreachstationY.Noreactanceexists,becauseahalfwavelengthopendipoleexhibitsresonance,justasatunedcircuitwouldifmadewithadiscreteresistor,inductor,andcapacitor.Thesynchronizationrequirestheuseofanexternalfrequency-and-timestandard,suchasthatprovidedbytheNationalInstituteofStandardsandTechnology(NIST)radiostationWWVintheUnitedStates.IfyoualsohaveVHFandUHFcapability,youhavethebestofeverythingthisrespect.Asuddenincreaseinthesolarfluxindicatesthatshortwavebroadcastingandcommunicationsconditions(includinghamradio)mightdeterioratewithinafewhours.Inadditiontothegenerator,IuseseveralextensioncordsandpowerstripstodistributeelectricitytothepointswhereIneeditthemostduringautilityoutage.Somesiteswillgiveyoucasehistories,horrorstories,andwildtalesaboutillnesses,pains,andcancer,andattributeallofthetroubletodirtyelectricity.Itcanimprovethesensitivityofareceiveratthefrontend,butit’simportantthatlinearitybeasgoodaspossible.SostriveforalowSWR,butdon’tobsessoverit.Thelossalsoincreasesiftheloadimpedancedoesnotmatchthecharacteristicimpedanceoftheline.Ifyoucommitthatoffense,youcanfacelargefines;insomecasestheyrangeinthetensofthousandsofdollars.SpeechCompressionandClippingSpeechcompressionisamethodofincreasingtheaveragepowerinavoicesignal,withoutincreasingthepeakpower.(Ifyouplantorunthelegallimit,anend-fed,randomwirewillprobablygiveyoutroublewith“RFintheshack.”)Whentunedwithagoodtransmatch(antennatuner),anend-fedrandomwireoffersdecentperformanceonanybandforwhichitmeasuresatleastanelectricalquarterwavelengthlong.Onsomenights,Icouldhardlyusethebandbecauseofinterferencefromthesestations.Thereflectorismadeofwiremesh,screen,orsheetmetal.ContestingOnmostweekends,oneormoreoftheHFhambandshostsacontest.WhenyoulookattheEMspectrumdisplayfromzerotoseveralthousandhertzusingDigiPan,you’llseethatutilityACenergycontainsnotonlythe60-Hzfundamental,butalsomanyharmonics.(Asachild,Iexperiencedthatmishapandpracticallyfelloverbackwards!Luckily,Ididnotsufferpermanenteyedamage.)Ideally,youshouldavoiddirectsunviewinginanyform,anduseatelescopeprojectionsystemthatcastsanimageofthesunonaflatscreen.Sunspotnumbers,ontheaverage,increaseanddecreaseinaratherwell-definedcyclethatlastsalittlelessthan11years.ThearrangementsatAandBworkwithunbalancedloads,suchasverticalandground-planeantennas;thecircuitsatCandDworkwithbalancedloads,suchasdipoleantennasandlargeloops.Ifyouconductin-depth,Internet-basedresearchintothissubject,you’llcomeacrossalotofsitesthatwarnabouthealthhazardsposedbydirtyelectricity.Manyhamshaveconfirmedcontactsinmorethan100countries,therebyqualifyingtojointheARRL’sDXCenturyClub,andsomehamshavemadeQSOsinmorethan200countries.6-12)withenhancedconnections(Fig.Itcoversthebandsfrom40metersthrough70centimeters.•Clickon“Options”inthemenubaranduncheckeverythingexcept“Rx.”•Clickon“Mode”inthemenubarandselect“BPSK31.”•Clickon“View”inthemenubaranduncheckeverything.IactuallyhadtowritedownwhatIheardonthespot,forasolidcontinuousminuteormore,withoutasinglemistake.Itwillpresentashockorfirehazardifyouuseit.Youmeasurethelevelofthenoiseatthespeakerterminalsunderno-signalconditions.•GeneralClassoperatorscanusethespansfrom14.025MHzto14.150MHzfordigitaloperation,and14.225MHzto14.350MHzforphoneandimagingcontacts.Aslongasneitherthetransmittingoperatornorthereceivingoperatordivulgethesequencingcodetoanyoneelse,then(ideally)nounauthorizedlistenercaninterceptit.Signalsshowupasverticallines.Ifyoudrivethroughtrulyremotelocationswhereyourcellphonewon’twork,anHFmobilehamradiosetwillservetogetyouhelp,evenifyouhavetocontactsomeonehundredsofkilometersawaytocallthestatetroopersforyou!Forthesereasons,thisbookwon’tdealanyfurtherwithCBradio.Ultravioletrayscanpenetratethe“celluloid”anddopermanentdamagetoyourvision.Don’tscrimponthisinvestment!Figure5-14showsthetwoACoutletsonmygenerator.However,DigiPancanalsofunctionasabasebandspectrummonitor,showingthepresenceofAC-inducedEMfields,notonlyat60Hz(whichyoushouldexpect)butalsoatmanyotherfrequencies(whichyoumightnotexpectuntilyouseetheevidence).FIGURE7-10Athree-elementYagiantenna.6-4.Eachframehas525linesinthescreenrenditionorraster.Withsomecompromise,however,youcansendavideoimageinamuchnarrowerband.MyArrangementTheHondaEU-2000iportablegasoline-fueledgenerator(Fig.Veryfewantennasystemsmeetthisrequirementtoperfection,butyoucanmatchalmostanyloadimpedancetoyourradiobymeansofatransmatch,whichcomprisesinductorsandcapacitorsthatcancelouttheantenna’sreactanceandconverttheremainingresistancetotheappropriatevaluetoprovideamatchtothecoaxialcable.Withouttherepeater,themaximumcommunicationsrangewouldbeabout50kilometersoverflatterrain,andlessthanthatoverirregularterrain.Downloadtheexecutablefileontoanexternalmedium,suchasaflash(thumb)drive,andthengiveitavirusscanwithagoodup-to-dateantivirusprogram,beforeyouinstallitortrytolaunchit.EmergencyPreparednessHamradiojustifiesitsexistencewhencatastropheswipeouthumanmadeinfrastructures.TheproblemislesssevereorfrequentatVHFandUHF.Otherprogramsexist,butmostofthemrequirepayment.(Exceptionshappen,ofcourse!)The30-meterbandcangoeitherway,acharacteristicthatmakesthat50-kHz-wideslotespeciallyinteresting.Tothatend,thetransmittergeneratespulsesattheendofeachlineandattheendofeachcompleteframeintheraster.ForascheduleoftheW1AWtransmissionsinallmodes,includingcodepracticeandofficialbulletinsofinteresttoradiohams,visittheARRLwebsiteatwww.arrl.orgThebestwaytolearnthecode,andgetbetteratitonceyouknowit,involveswritingdownreceivedcharactersonpaper,anactivitycalledcopyingCW.IwasastonishedwhenIsawthenoisegofromoverS-9onmyreceiversignalmeterdowntoonlyaboutS-3!That’sareductionofsixSunits,whereeachSunit(onmostreceivers)representsabout5dB.Thisarrangementproducesvoltagesandcurrentsattheendsofthesecondarywindingthatopposeeachotherinphase.However,notalloftheseprogramsworktotheirfullpotentialonneweroperatingsystems,andafewofthemmightnotworkatallonsomecomputers.•Profanityorinsultinglanguageinanymode.StationEquipmentforRTTYIfyouwanttostartworkingRTTYrightnowandyoudon’twanttotakethevintage“teleclunker”route,you’llneedacomputer,andprobablyalsoaseparateinterfaceunit.TheAdvancedClasslicensehasvanishedoncemore.Iftheydon’thavephysicalunitsrightontheirshelves,gototheRadioShackwebsiteandyou’llfindawiderangeofmodels,oneofwhichwillsurelysuityourdesires!Theirhomepageisatwww.radioshack.comMayIalsosuggestthatyouattendameetingofalocalhamradioclub,orstopbyoneofthehundredsofhamradioconventionsthattakeplacenationwide?Inheavyportableoperations,avoidthetemptationtokeepoperatingasathundershowerapproaches.FIGURE1-17Atunablepreamplifier.AdvantagesofQROMobileMostmobileoperators,especiallywhenoperatingintheHFbands,prefertorunthestandardRFpowerofabout100wattsthatmosttransceiversputout.Thenarrowbandfilterrespondsonlytothefrequencyorchannelofaspecificsignalthatyouwanttohear,andrejectssignalsinnearbychannels.Thosemachinesshouldremainavailableforpriorityandemergencycommunications.Hereareafewoftheonesthatyoushouldthinkaboutbeforeyoubuyashortwaveradio.Ifthat’sallyouneedtostartoutwith,that’sfine,butsoonerorlateryou’llprobablywanttoaddmorestuff.Andfinally,ifyouliveinanRF-noisylocationasIdo,youmightaswellforgetaboutmoonbounce!Thebestlocationshaveundergroundelectricallinesandresidentiallotsbigenoughsothatneighborswithrogueelectricalappliancescan’truinreception.Nearlyalloftheseradiosrun4wattsRFpoweroutputandusetheAMmode.Figure1-14CshowsahypotheticalPIMsignal.TheEMwavesthatyouwanttohear,andtheonesthatyoudon’twanttohear,bothoriginateandpropagateinthesameway,asFigs.Curious?Iftheotheroperatorscanhearyouanddon’tmindyourbreakingin,they’lleithercallyoustraightaway,orelseask“Who’sthebreaker?”orsomethinglikethat.ThepeopleatARRLheadquarterscantellyouthelocationsofsomeAmateurRadioclubsnearyou,whereyoucanmeethamsofall“stripes.”CitizensBand(CB)RadioTheCitizensRadioService,alsoknownasCitizensBand(CB),isaradiocommunicationsandcontrolservice.Butthewavesareshort,andthefrequenciesarehigh,comparedtotheonesusedforradiocommunicationsandbroadcastingwhenthetermsoriginated.Asequenceofpulsescalled“linefeed”causestheteleprintercarriageorcomputerdisplaytobackupandmovetothenextlinebeforeprintingwillresume.Iuseadeepcyclemarinebattery(Fig.Table8-4showssomeofthemostoften-usedones.Inanalternativearrangement,themagneticpolesrevolvearoundthewirecoil,whichremainsfixed.WhereWillYouPutYourRig?Thecomputer,withtheproperprogramandaudioinput,canreadanddisplayRTTYonyourmonitorrightoutofthebox.SynchronizedCommunicationsDigitalsignalsrequirelessbandwidththananalogsignalstoconveyagivenamountofinformationperunitoftime.•MechanicalfiltersandceramicfiltersareIFbandpassfiltersfoundinafewhigh-end,vintage,dual-conversionreceiverswithlow-frequency,secondIFchains,notablytheoldCollinsRadioequipment.OnafairafternooninJune,andparticularlyifthesunspotcycleisnearitspeak,youshouldexpecttohearplentyofsignalson10,12,15,17,and20meters,afewon40and30meters,veryfewifanyon60meters,andonlylocalsandregionalson80meters.Youcanleavemessagesforaslongasyouwant,andthendeletethemwhenyouwantthemgonefromthesystem.Imagerejectionistheextenttowhichimagesareattenuatedwithrespecttoasignalonthedesiredfrequency.Thehalf-wavelengthloopexhibitsaslightpowerlossrelativetoahalfwaveopenorfoldeddipoleinitsfavoreddirections(thephysicaldirectionsinwhichitoffersthebestperformance).Gerrish,Howard,ElectricityandElectronics.WanttoKnowMore?Figure5-4isasimplifiedschematicdiagramofascaled-down,broadbandlinearthatoperateswithasinglepowertransistor.Opentheaudiocontrolprogramonyourcomputer.Thesystemcomprisestwoidenticalreceiverstunedtothesamesignalandhavingseparateantennasspacedseveralwavelengthsapart.Astronomerscan“hear”thisnoisewithradiotelescopes.Thenoiseantennawaswireafewfeetlong,runningunderarugonthehallwayfloor.Onceinawhile,you’llheara“lid”(pooroperator)onthisbandwhosimplyactshostileorirrational.Problemscanalsooccurwithcosmicnoisewhenthemoonpassesnear“bright”regionsintheso-calledradiosky.Ifasolardisruptionsuddenlysendsahugequantityofchargedsubatomicparticlesintheearth’sdirection,anEMPcanoccurwhenthe“tsunami”ofparticlesencounterstheearth’smagneticfield,whichacceleratesthechargecarrierstowardthegeomagneticpoles.Theimageresolutionofahigh-qualityfaxisgoodenoughtoallowreproductionofmostphotographs.Don’tmakeahabitofchewingtheragonrepeaters.Nearlyalltransmittingantennascanreceivesignalseffectivelywithinthedesignfrequencyrange.AllocationsbyLicenseClassIfyouhaveaGeneral,Advanced,orExtraClasslicense,youcanoperateonanyfrequencywithinthe17-meterband.Thismethodofrectificationhasshortcomings.Unfortunately,anynearbyACutilitylineorhousewiringproducesEMenergynotonlyat60Hz,butalsoatharmonics(whole-numbermultiples)of60Hz,aswellasatotherunrelatedfrequencies.6MetersAmateurRadiooperatorshave6-meterprivilegesbetween50.000MHzand54.000MHz.Intermsoffrequency,6metersconstitutesthelowestofthethreeVHFhambands,theothersbeing2metersand1.25meters.Sometimesyou’llhearonlyoneofthestations,sothe“tweets”willalternatewithbriefperiodsofsilence.Atsomehigherradiofrequencies,theloweratmospherepreventsthenoisefromreachingus.Thenyoureplacetheantennawitharesistance/capacitance(RC)orresistance/inductance(RL)circuitandadjustthecomponentvaluesuntilthetransmitterbehavesexactlyasitdidwhenconnectedtotherealantenna.Here’sawaytocalculatethefree-spacewavelengthofaradiowaveifyouknowitsfrequency:Divide300(theapproximatespeedoflightinmillionsofmeterspersecond)bythefrequencyinmegahertz.InVOXoperation,thetransmitterisactuatedwithinafewmillisecondsafteryouspeakintothemicrophone.Parallel-WireLineParallel-wirelineiscommonlyusedwithbalanced(symmetrical)antennas,suchasdipolesandmostYagis.Ifyoucanmakethecounterpoisebiggerthanthat,thendoit!GainandDirectivityThepowergainofatransmittingantennaequalstheratioofthemaximumeffectiveradiatedpower(ERP)totheactualRFpowerappliedatthefeedpoint.Let’scallit3kHz.FIGURE1-5DrawingAshowsanomographoftheelectromagnetic(EM)spectrumatwavelengthsrangingfrom108meters(m)downto10−12m.IntheUnitedStates,theproliferationofcomputersandInternetcommunicationshaslargelyovershadowedSWLsincethe1980s,andmanyyoungAmericansgrowupignorantofarealmofbroadcastingandcommunicationsthatstillprevailsinmuchoftheworld.Theuppertraceshowsatime-averagedresponse;thelowertraceshowsaninstantaneousresponse.Ifyoudrivetoomuchcurrentthroughadiode,theresultingheatwilldestroyit.Withold-fashionedMorsecode,youcanhearasignalanddecodeitinyourhead,nomatterwhereithappenstoshowupinyourpassband.TrueDXingmeansworkinghamsinlotsofdifferentrecognizednations,nomatterhownearordistant.1-8willperformquitewell,aslongasyoudon’tlettheaudioinputlevelgettoohigh.Thunderstormsproducesferics(sometimescalled“static”),aformofradionoisethatcanimpedeorruinsignalreception.Thisarrangementcancelsoutthecarrierwaveintheoutputsignal,leavingonlyLSBandUSBenergy.7-2C.Whenaskipzoneexists,ittendstoexpandduringthehoursofdarknessandshrinkduringthehoursofdaylight.Irememberthedayswhenhamsdreamedofhavingabandhere;40metersand20metersseemedseparatedbyagiganticgulf.Inthatcase,youcouldgetthesame“signalbang”withfarlesstransmitterpower.It’sthesameeffectthatmakessoundwavestravelforlongdistancesundercertainconditions,suchasacalmeveningonabiglake.7,I’llexplainhowradiationresistanceandlossresistanceaffecttheefficiencyofanantennasystem.Thebridgecircuitalsoplaceslessstrainontheindividualdiodesthanahalf-waveorfull-wavecenter-tapcircuitdoes.Thefull-wavelengthloopshowsaslightgainoveradipoleinitsfavoreddirections.Inmobilestations,amarginalgroundsystem,usuallycomprisingonlythevehiclebody,compoundstheproblem.Anyonewithashortwaveradiocantuneinandheareverythingyousay.6-8and6-9comprisesaready-madelengthofRG-213coaxialcable(thebestkindcommonlyavailableforradiohams),33meterslongwithmoldedconnectorsoneitherend.SomeengineersdefineCWspeedasthenumberoftimesthattheword“Paris,”alongwiththeseven-bitpauseafterwards,repeatsinoneminutewhensentoverandoverinperfectlyformedcode.•Front-endspecificationsgetmoreimportantasthefrequencygetshigher,andattainparamountsignificanceatVHF,UHF,andmicrowavefrequencies.Inthereceiver,thedemodulatorrecoversthesesynchronizing(sync)pulsesandsendsthemtothedisplay.Thenitwilldropout(stoptransmittingaltogether).Inanycase,youmustidentifyyourstationattheendofthecontact,andatleastevery10minutesduringthecourseofthecontact.Loopsticksareoftenusedalongwithpreamplifiersinhigh-radionoiseenvironmentstoenhancereception.TheEMfieldinducesacurrentsurgethatflowsalongthecontrollinebetweentheradioandthetransmatch.2,you’lllearnthebasicsofshortwavelistening(whichIextendtoallwavelisteningbecausemodernradioreceiverscoverfrequenciesthatrangefaraboveandbelowthetraditionalshortwaveradiofrequencies).Soifyoutuneinastationsothatitspitchmatchesthesidetonepitch,youknowthatyou’rezerobeatwiththatstation,aslongasyoudon’thaveincrementaltuningswitchedon.Alwayscheckforvoltagebeforemeasuringresistance!Wearyourglovesatalltimes.Soifyouhavea40-meterdipolestrunguprightnow,tryiton15metersandseewhathappens.Trythesametestswithahairdryer,anelectriccanopener,oranyotherappliancethatplugsintoawalloutletandcontainsanelectricmotor.ChooseYourBandWhenyoupowerupyourradio,you’llhavetochooseabandforoperation.Thecordontheleftgoestothefurnaceelectronicsandfan;thecordontherightgoestothehamshack.2-1.Youcanfindseveral“buildandplay”VLFconverterdesignsandevensomecommerciallymanufacturedunitsonline.Figure5-7isasimplifieddiagramofavoltage-doublerpowersupply.Thepowerstripsincludebreakersbutnottransientsuppressors;theUPScontainsatransientsuppressorthatservesthewholesystem.HowIGotintoSWLMySWLexperiencedatesbacktoelementaryschoolinthe1960s,whenmydadboughtmearadioprojectkitformybirthday.You’llfindtwotypesofreceivingantennasincommonuseatLFandalsoatVLF:1.TABLE4-4SuballocationsintheUnitedStatesforthe20-meterband(14.000MHzto14.350MHz)asofMarch2012.Agiganticvoltageconstantlyexistsbetweenthesurfaceoftheearthandtheionosphere.TheoutputoccursateitherthesumorthedifferenceofthesignalfrequencyandtheLOfrequency.Blackdotsrepresentendusers.Enterthenameoftheprogramofinterestintoyourfavoritesearchengine,andfollowthelinksuntilyougetadownloadthatworks.TheMorsecodeisamark-onlycode;spacesareactualcarriergaps,duringwhichyourQSOpartnercanbreakinonyouifyourradiohasthecapabilitytohearduringthosegaps.Ifyouuseacomputerverymuch,andespeciallyifyou’reinterestedinhardwaredesign,youshouldfinditeasytogetanAmateurRadiolicense.Ifyoudohearit,nowyouknowwhatitmeans!CarryingonaQSOThelengthandcontentofaCWQSOdependsonthecircumstances.Ifyou’remarried,yourspousemighttakeexceptiontoyourdemandinganentireroomforyourradiostation,butthenagain,maybeshe(orhe)willbehappythatyoudon’twanttoputthatgeekygearoutinplainsight,wherehouseguestswillseeitandcatswillmakemischiefwithit.•NoisequietingisanexpressionofthenoisereductioninanFMreceiverasaresultofanincomingsignal.AnotchfiltercanmuteaninterferingunmodulatedcarrierorCWsignalthatproducesaconstantfrequencytoneinthereceiveroutput.Forexample,aradialfor7.030MHzwillmeasure33.3feet,or10.1meters,long.•Anoiseblankerblocksthereceiverforafewmillisecondswhenanoiseimpulsecomesin.Thiseffectoccursbecausethelowestlayeroftheionospherebecomeslessreflectiveandmoreabsorptiveasthefrequencyrises,andalsobecausethegroundbecomeslessconductivesothatthesurfacewavecan’tpropagateaswell.Myvehiclealreadyhada2-meterFMmobileradio,alsobyYaesu(Fig.Ithasasinglelever,thetypethatIprefer.Don’tactlikeanidiot,asIdidthatnight(andmorethanafewtimessince)!PostscriptAfterreturningfromWyominginthewinterof2014,IinstalledtheActiveTuningAntennaSystem(ATAS)thatIoriginallygotalongwiththeFT-857D.FIGURE5-10Avoltage-regulatorcircuitusingaZenerdiodeandatransistor.7-8B,producingabidirectionalradiationpattern.Useofthisworkissubjecttotheseterms.(Thetiedupcordisthegroundwire.)DidYouKnow?(Actuallyittookmeuntilthesixthgrade,atage12.)Idon’tknowhowIwouldhaveheardabouthamradio,wereitnotforSWLinthosedaysofstuffingpiecesofwireintospringcontactsonacircuitboardwithcapacitors,coils,resistors,anda1T4vacuumtubeaboutthesizeofmythumbthatranoffofa45-voltbatteryanda1.5-voltflashlightcell.Asingletrailrarelylastslongenoughtoallowtransmissionofmuchdata.Youcantryoutthe“Help”menu,butitmightnotworkonallcomputers.Figures1-18DandEshowproduct-detectorcircuits,whichcanalsoserveasmixersinsuperheterodynereceivers.(Thefundamentalfrequencyisthefirstharmonicbydefinition).AmongthefirstpeopletodreamitupwerethecomposerGeorgeAntheilandtheactressHedyLamarr,whoreceivedaU.S.patentforaspread-spectrumprocessin1942!MultiplexingSignalsinacommunicationschannelorbandcanbeintertwined,ormultiplexed,invariousways.Attheveryleast,you’llneedacomputer,althoughitdoesn’thavetobeapowerfulone.EngineerssymbolizeitasZo.FactoidThecharacteristicimpedanceofagiventransmissionlinedependsonthediameterandspacingoftheconductorsused,andalsoonthetypeofdielectricmaterialthatseparatestheconductors.Warning!OperatingwithQRPIfyoulikechallenges,low-poweroperation(calledQRPaftertheQsignalforreducingpower)willprovideyouwithplenty.•Inanemergency,you’llhavethebestchanceofgettinghelpintheleastamountoftimeifyourunthehighestRFpoweroutputthatyou(andyourvehicle’selectricalsystem)canmanage.Youalsogetmostoftheselectivityhere,filteringoutunwantedsignalsandnoisewhileallowingthedesiredsignaltopass.Onceyougetupto275GHz,youcancommunicateonanyfrequencyyouwant,includingmicrowaves,infrared(IR),visiblelight,ultraviolet(UV),X-rays,andevengammarays,assumingthatyoucancomeupwithatransmitterandreceiverthatwillworkatthosemicroscopicwavelengths!DidYouKnow?Ifnoenergyexistsatanyfrequencyintheprogram’srange,thedisplaywillappearcompletelyblack.Figure1-3isablockdiagramofatypicalhomehamradiostation.Thisdrawingshowstwohypotheticalexamples.IntheoriginalRSTsystem,whichremainedinuseuntilabout1970,oneofthetonenumbersstoodfor“musicallymodulatednote.”Also,theothertonenumbersconveyedmeaningsmorediversethanhair-splittingseverityindicatorsforACripple.Suchafunctioncanbecomplicatedindeed.Removetheendoftheantennaentirelyfromthehouse,andlayitonthegroundwherenobodycantripoveritorotherwisegetintroublewithit.Resistancesareinohms.Variousotherrulesexistforspecialsituations.Ifyouhaven’tyetboughtorbuiltaradio,doubtlessyou’lldoitsoon,likelatertoday!Inthischapter,afterahalfcenturyasaparticipantintheAmateurRadioart,I’llofferabitofadviceconcerninghowtogetthemostoutofallthatnewhardwarewhenyougetontheair.ACWsignalneedsonlyabout100Hzofbandwidthinordertobeclearlyreadatmostspeedsthathamsuse.Second,theoutputvoltagecandropconsiderablywhenthesupplymustdeliverhighcurrent.Figure2-6showsthesunspotcyclessincetheyear1920asaveryapproximategraphofrelativeactivityversustime.Anotherwaytoobtainspread-spectrumemission,calledfrequencysweeping,requiresfrequency-modulatingthemaintransmittedcarrierwithawaveformthatguidesitsmoothlyupanddowninfrequencyovertheassignedband.•MostQRPstationsarelessmassiveandcontainfewerindividualboxesthanQROstations,makingQRPstationseasiertodeployanddismantle.Thebatterywilllastlongerbetweenchargesandwillbelesslikelytosufferfromavoltagedropbecauseofitsowninternalresistance.What’sThat?Theinputsignalgetsconvertedintoelectromechanicalvibrationbytheinputtransducer.Nonlinearitygivesrisetoawidevarietyofproblems,especiallyifyouusethepreamplifierwhensomeofthesignalsarestrong.TipCallore-mailtheARRLHeadquartersHelpDepartmentifyouareanaspiringhamradiooperator.•WithQRO,you’llhaveabetterchanceofmaintainingacontactonceyou’vemadeit,especiallyinlightofthefactthatmobileoperationofteninvolvesmovingthroughzoneswherelinesofsightchangebecauseofhillsandbuildings.Asthingsworkedout,somehamsendedupamongthemostvaluableengineersthattheartofcommunicationshaseverknown.•PortableHFradioscanserveasemergencycommunicationsstations.Youneverknowwhatwillhappenuntilyouactuallytestyourideaandfindout.DirtyElectricityAsyoulearnedinChap.IfyouholdaNovicelicense,youmustupgradebeforeyoucantransmiton2meters.Coronaewereobservedbyseafaringexplorershundredsofyearsago.Awell-designed,three-elementYagiexhibitsabouta7-dBdgaininitsfavoreddirection.TheFCCregulatesthebehaviorofcommerciallymanufacturedtransmittersinthisrespect.Half-WaveCircuitThesimplestrectifiercircuit,thehalf-waverectifier(Fig.Themoresensitivethereceivingequipment,andthelongerthedistanceoverwhichithastowork,themoresignificantthistypeofnoisebecomes.Inpulse-amplitudemodulation(PAM),theamplitude(strength)ofeachindividualpulsevariesaccordingtothemodulatingwaveform.Ifyouneedlessgain,turnthetransmittercontroldowninsteadofwhispering.Whileyoucanhavefunlisteningtopeoplewholivethousandsofkilometersawayonasimpleradiounit,thosesamestationscandrownoutlocalones,perhapstherancher“nextdoor”withwhomyouwanttodiscussbusiness(whichislegalonCBradio),orthehighwaypatrolofficerwhomyouaretryingtoreachwhenyourtruckbreaksdowninsomeremoteplacewherecellphoneswon’twork.Useyourfavoritesearchenginewiththephrase“dummyload”ifyouwanttoshopforone!Irecommendthatyouuseadummyloadwheneverpossible,soastoavoidcausinginterferencetoyourfellowhamsontheair.Onthisparticularband,youmayuseonlydigitalmodesonthelowermost100kHz(3.500MHzto3.600MHz).Oftenitformsin“clouds”andcanchangeitscharacterrapidly,hencetheoriginofthetermsporadic-Epropagation.Ifyousee0foralloftheACandDCvoltageresults,switchyourmultimetertothehighestresistancefunction.Inashortwaveorhamradioreceiver,anoiseblankercanoftenworkwonderstogetridofignitionnoiseproblems.Infact,somepeople,havingtriedCBanddecidingthattheyhavenouseforit,givetheir

radiosaway.WhenIwasanewlylicensedhamradiooperatorinthe1960s,Itookadvantageofthesestations’broadcaststocalibratemyradioforoperationonthe20-meterhamband,andalsotosetmy24-hourclock,whichranoffofstandardutilityelectricity.Also,astheradiallengthincreasesandallotherfactorsremainconstant,vertical-antennaefficiencyimproves.Thespectrumbelowafewkilohertzsuffersfrom“EMpollution”onaccountofthisdirtyelectricityinanyareaservedbyanelectricutility.Thesequencecanchange,buttheratioisalways4:3.Instead,ASCIIisreservedforotherdigitalmodeswe’lldiscusslaterinthischapter.Thelowerpartofthescreencontainsatuningaidcalledawaterfall.Atgreatdistancesfromthewire,theEandMlinesoffluxareperpendiculartoeachotherinanearlyflatplane,forminganEMfieldthattravelsthroughspaceatthespeedoflight,asshowninFig.StationY,therefore,lieswithintheskipzonewithrespecttostationXatthefrequencyofinterest.TheincomingsignalcombinesinamixerwiththeoutputofanunmodulatedLO,reproducingtheoriginalmodulatingsignaldata.AtB,anincorrectmethodforgroundingmultipleequipments,creatingRFgroundloops.Half-WaveVerticalImaginethatyoustandahalf-waveradiator“onitsend”andfeeditatthebase(thebottomend)againstanearthground,couplingthetransmission(feed)linetotheantennathroughaninductance-capacitance(LC)circuitcalledanantennatunerortransmatch,designedtocanceloutthereactanceandtransformtheremainingresistanceto50ohms.Indaysgoneby,Techscouldn’toperateonanyoftheHFbands;theywereconfinedto50MHzandabove.InFDM,thechannelisbrokendownintosubchannels.AllocationsbyModeYoumayuseonlydigitalmodesonthelowermost150kHz(14.000MHzto14.150MHz),includingCW,RTTY,PSK,MFSK,datatransmission,andtheir“cousins.”Between14.150MHzand14.350MHz,youmayputoutphoneandimageemissions.Similarly,theremotereceivingstationmustfrequentlytransmittherequests.Besidesmatchingimpedances,awell-designedandproperlyoperatedantennatuneractsasalowpassfilterorbandpassfilter,providingadditionalfront-endselectivityforyourreceiver,improvingtheimagerejection,andreducingtheriskoffront-endoverloadincaseofastrongsignalofffrequency.Lookforradiosthatapproachthisidealascloselyaspossible.YoumightheartheDXstation’ssignalbetweenburstsofstatesidecallsifit’susingthesamefrequencyasthestationscalling.WhenIwasakid,oneofmydad’sfavoritesayingswas“Silenceisgolden.”Well,sometimesthat’strue,butifnobodyeversentoutanysqueaksorsquawksonthehambands,we’dloseourprivilegesforlackofuse.Nevertheless,goodoperatorsspendmoretimereceivingthantheyspendtransmitting.Today,it’stechnicallycalledthehigh-frequency(HF)band.Break-In(orNot)Anotherdifferencebetweenold-fashionedCWandthedigitaltextmodesisthefactthat,withthedigitalmodes,youcan’toperatefullbreak-inasyoucandowithCW.Youcanletthewireslieanywhere,aslongasyoudon’ttripoverthem!ThisarrangementwillmaketheaudiocordpickupEMenergy.Ifyoudothat,partofyouremittedenergywillstrayoutsidethechannelonthehighend.Whenmost,orall,ofthepathliesindaylight,youcanhear,andbeheard,overdistancesuptoaround5000kilometersonaregularbasis.Thereflectormustbeatleast0.8wavelengthindiameteratthelowestoperatingfrequency.Allthecomponentsinthesystemshouldbegroundedbyindividualwirestoasinglepoint.•Youcanputaradioinabackpackforlightportableuse,andlettheantennastickupoutofthebackpackfor2to3meterswithouttrouble.Figure7-5showsaproperRFgroundscheme(atA)andanimproperone(atB).Inthebestcommerciallymanufacturedgenerators,theinverterproducesanear-perfectsinewavetoensurethatthemachinecanproperlyoperatesensitiveelectronicdevices,suchascomputers,computer-controlledradios,printers,scanners,modems,androuters.Sometubularlinesarehermeticallysealedandfilledwithinertgastoeliminatethistrouble,butsuchlinesareexpensive,andtheycannotbecutifyouwanttotrimthelinelength.“TanglewireGardens”Mostofushavecomputerworkstations,usuallywithmultipleperipheralsandancillaryequipment,suchasaprinter,ascanner,amodem,arouter,acordlessphone,adesklamportwo,achargingbay(fordevicessuchastabletcomputersandcellphones),andsoon.CornerreflectorsarewidelyusedinterrestrialcommunicationsatUHFandmicrowavefrequencies.•YourradioplacesminimalstrainonabatteryifyourunQRP,evenifyoutransmitinamodethatinvolvescontinuouscarrieroutput,suchasFM.It’sfuntoletpowerhousestationscontactaDXstationorspecialeventstationoneafteranother,listentothemsnaretheirpreyforafewminutes,andthen,likeamousebetweenthefeetofanelephantherd,snagapieceofthatgameforyourlog—butonlybecauseyou’vedoneyourhomework.Sometimes,radioenthusiastsignorethedistinctionbetweentheF1andF2layers,andspeakofthemtogetherastheFlayer.Thismodeisknownaschannelscan.HamsusingSSBinthispartofthebandwillnoticethesesignalsastheypassthroughreceiverproductdetectors;they’llsoundlikeheterodynesor“beatnotes”withspace-alien-like“monkeychatter”superimposed.Ifanyoneevercarestotakeadvantageofthisband,worldwidecoveragewilloftenbepossibleoverdaylightpathsduringtimesofhighsolaractivity.YoumightexpandthisconcepttoCOEISASWH(“clickoneverythinginsightandseewhathappens”).Lookforthehighestpossiblenumber.Thesekeyboardkeyersfirstcameoutinthe1970stomeetthedemandsofhighspeedCWoperatorswhowantedtocarryonconversationsat50wpmormore.That’sbecauseawell-engineeredverticaloffersalowangleofradiationandreception,avirtualnecessityforDXoperation.ExceptaspermittedundertheUnitedStatesCopyrightActof1976,nopartofthispublicationmaybereproducedordistributedinanyformorbyanymeans,orstoredinadatabaseorretrievalsystem,withoutthepriorwrittenpermissionofthepublisher.ConvertersforVLFIfyouwanttolistentosignalsatfrequenciesbelow30kHzandyourreceivercan’tdoit,youcanbuildaconverterthatwillletyoulistenallthewaydowntoDC(0Hz),atleastintheory.Whenoneofthestationsendsatransmission,sayyourcallonce,clearlyandwithoutphonetics.Atornearasunspotcyclemaximum,theMUFriseshighestbecausetheearth’supperatmosphereattainspeaklevelsofionizationasaconsequenceofthehighsolarflux.ThisisW1GV.Nooneansweredmycallsintotheetherthen,ofcourse,buttheydidafterIgotmyfirsthamradiolicensein1966.Thecharacteristicimpedancerangesfrom300ohmsforaclose-spacedladderlineto450ohmsforthewide-spacedtype.Thebrighterzonearoundtheumbraconstitutesthepenumbra,asshowninFig.Apoorsystemhasgroundloopsthatactlikeloopantennas,givingrisetoallsortsofhavoc.Thismotion,calledlibration(notliberationorlibation)producesrapid,deepfluctuationsinsignalstrength,aphenomenonknownaslibrationfading.Thatway,you’llalwaysbeabletoheartheDXstationwhenittransmits,evenifdozensofotherstationshappentoaccidentallycallatthesametime.Parallel-wirelineiscommonlymoldedintheedgesofpolyethylenestrips.Niles,IL:MasterPublishing,2003.Iheardnothingbetween18.900MHzand19.020MHz.13MetersTheshortwavebroadcast13-meterbandliesimmediatelyabovethehamradio15-meterbandintermsoffrequency,coveringarangeof21.450MHzto21.850MHz.Conditionshereareessentiallythesameastheyareonthehamradiobandat21.000MHzto21.450MHz.Whenthesunisina“vibrantmood,”youcanexpectgoodreceptiononthisbandforanypaththatexistsentirely,ormostly,onthedaylightsideoftheearth.The“MainRadio”PeripheralEquipmentUtility-OperatedPowerSuppliesSmallBackupGeneratorsNoise,Noise,Noise!6MobileandPortableHamStationsMobileBandOptionsMobilePowerOptionsPortableBandOptionsPortablePowerOptionsStaySafe!7HamAntennaPrimerRadiationResistanceHalf-WaveAntennasQuarter-WaveVerticalsLoopsGroundSystemsGainandDirectivityPhasedArraysParasiticArraysAntennasforUHFandMicrowaveFrequenciesTransmissionLinesStaySafe!8HamOperatingBasicsListen,Listen,Listen!Don’tBeaLid!SignalReportingOperatinginSSBOperatinginFMOperatinginCWOperatinginNon-CWTextModesContestingWorkingDXRagChewingOperatingwithQRPEmergencyPreparednessAppendixASchematicSymbolsAppendixBQSignalsforHamRadioAppendixCTen-CodeSignalsforCBRadioAppendixDTen-CodeSignalsforPoliceandEmergencyPersonnelSuggestedAdditionalReadingIndexIntroductionThisbookwillhelpelectronicsenthusiastslearnabouttwohobbiesthatescapetheattentionofmostoftoday’stechnophiles:shortwavelisteningandAmateur(or“ham”)Radio.•MostVHFandUHFradiosaresimple,compact,andeasytooperate.YoucangetsomeofthemasdownloadablefreewareontheInternet.Butwhyletitlapse?Somereflectometershavetwoseparateneedlesandthreescales.(Afewsingle-bandeventsdoexist,suchastheARRL160-meterand10-metercontests,heldeveryyearinDecember.)TipBeforedivingintoanycontest,listentosomeexchangesbetweenotherstationssothatyougetagoodsenseofthewaythingsshouldgo.Otherlicenseclasseshaveprivilegesasfollows:•AdvancedClasslicenseescanusetherangesfrom14.025MHzto14.150MHzfordigitaloperation,and14.175MHzto14.350MHzforphoneandimagingoperation.I,alongwitha(dwindling)fewothers,loveit.Thatantennawillworkokayforreceivingstrongsignals,butyourbestoptionforseriousSWLisanoutdoorrandomwireatleast20meterslong,andmuchlongerifyoucanmanageit.Inanantennasystem,lossresistance“gobblesup”theenergyandturnsitintouselessheat,whileradiationresistanceputstheenergyintotheairwavesasyourtransmittedsignal.Afewbasictipsfollow.Inmostdirectionalantennasystems,theright-handandleft-handf/sratiostheoreticallyequaleachother.YoucaneasilymovethehardwareforaheavyportablestationfromonefixedQTHtoanother,butyoucan’tusethegearasyoucarryit.1-5B,wheretheaxisislabeledaccordingtofrequency.(Ofcourse,wehavecellphonesnowtoo,sothatfamilyprobablywouldnotneedahamlikemeinasimilarsituationnow.)Thetoneisasteadysine-waveaudionotethatmodulatestheFMcarrieratafrequencybelowthestandardvoicepassband.Thisdesignschemeincreasesthegainandf/bratiocomparedwithatwo-elementYagi.ExoticCommunicationsMethodsCommunicationsengineershavealonghistoryofinnovation,developingalternative(andsomedownrightweird)wirelessmodes.SpeechclippingisanalternativemethodofincreasingtheaveragepowerofanSSBsignalwithoutincreasingthepeakpower.Inmostlocations,theeffectivegroundcomprisesanimaginaryplaneorcontouredsurfaceslightlybelowtheactualsurfaceoftheearth.Thisphenomenonwillmostlikelyshowupatfrequenciesrangingfromabout12MHzto18MHzduringtimesofpeaksunspotactivity.Ratherthanputatrademarksymbolaftereveryoccurrenceofatrademarkedname,weusenamesinaneditorialfashiononly,andtothebenefitofthetrademarkowner,withnointentionofinfringementofthetrademark.Iplacedtheantennainaso-calledballmountsecuredtothelipofmypickuptruckbed,asshowninFig.SolarNoiseTheamountofradionoiseemittedbythesuniscalledthesolarradio-noiseflux,orsimplythesolarflux.Ihaveuploadedalotofhamradiovideostothatvenerablesite.Let’sexaminesomewavepropagationbehaviorsthataffectwirelesscommunicationsatradiofrequencies,andthat,ifyoutakeupanysortofradio-relatedhobby,willinterestyou.QuickLookTable4-1offersanat-a-glanceoverviewofthehambandsavailabletooperatorsintheUnitedStates.Afilterwithapassbandgoingfrom300Hzto3000HzcanimprovethequalityofreceptioninSSB.YoucanexpectanexcellentS/Nratiointhepresenceofweaksignalsonlywhenyourreceiverhasalownoisefigure,whichisameasureofinternallygeneratedcircuitnoise.How’sYourLuck?Duringthe1970s,CBradiobecamepopularamongtruckers,andremainssotothisday,especiallyintheAmericanSouth.Duringthedaytime,theDlayerionizestotheextentthatitprevents1.8-MHzradiowavesfromgettingtothehigherlayerswheretheycouldotherwisebendbacktothesurface.Astheimpedancemismatchbetweenthelineandtheload(antenna)getsworse,thevoltageandcurrentfluctuations,andtherefore,thestandingwaves,growmorepronounced.AtB,thepassageofapacketthroughnodesinawirelesscommunicationscircuit.Thetransmissionrateisusuallyalotslower,too,withacompleteframetakingupwardsofafullminutetorender.Inotherwords,theinstantaneousoutputisalinearfunctionoftheinstantaneousinput.Anddon’tforgetthatyoucanalwaysdosomehammingonweekdays,too!ATechie’sConfessionIlovetobuildandtestantennasystems,andI’vefoundconteststobeagoodwaytolearnhowwelltheywork,especiallyifIrunlowpower(QRP).Inpositivemodulation,theinstantaneoussignallevelisdirectlyproportionaltothebrightnessatanygivenpointontheimage.Yourtransmittermustnotputoutmorethan100wattsPEP.Istillhavethatkeyinmy“hamshack”today,althoughIdon’tuseitanymore.They’reintuitive;playingwiththeprogramandyourradioforafewminuteswillteachyouallyouneedtoknowabouthowtheywork.Thetwowavesmightarriveatthereceivingantennainperfectphasecoincidencesothattheyreinforceeachother,butusuallytheydon’t.Forreceptionofon/offkeyedMorsecode,theLO,whichtechiescalledabeat-frequencyoscillator(BFO)beforeabout1980,issetafewhundredhertzaboveorbelowthesignalfrequency.YoucanminimizeIMDbyadjustingtheinterfacegain,computeraudiooutput,and/ormicrophonegaincontrolsinyourradiosothattheaudiolevelremainsslightlybelowthethresholdatwhichyourradio’sautomaticlevelcontrol(ALC)kicksin.8.Someradioscansearchforeitheravacantfrequencyoranoccupiedfrequency.Insomecases,itcangodownaslowasabout65%.OldtimerswillremembertheseservicesasLORAN,anacronymthatstandsforLOngRAngeNavigation.Theycalledthenewcommunicationsmodesinglesideband(SSB),atermwhichendurestothisday.AtB,thefluxlinesfarawayfromacurrent-carryingwire.VelocityFactorTheforegoingformularepresentsatheoreticalideal,assuminginfinitelythinconductorsthathavenoresistanceatanyEMfrequency.Obviously,yourbattery’slifebetweenchargingsessionsvariesininverseproportiontothecurrentyoudemandfromit.Legalissuesaside,thishobbyissupposedtoprovideadistractionfromworkadaystuffanyway,isn’tit?Frequencydividersgeneratethenecessarysynchronizingsignalsfromthefrequency-standardsignal.Ifyoucalltheradiusoftheconductorsrandthecenter-to-centerspacingd,asshowninFig.Thisprogram,likeDigiPan,hasasmall“footprint”onapersonalcomputer,andwilldownloadfast.StayTuned!Atthetimeofthiswriting(late2013),hamradiooperatorshavebeguntodiscusswhetherornotthetraditionalbandwidthlimitationsfordigitaltransmissionsontheHFhambandsoughttobeincreasedtoallowforhighercommunicationspeeds.TipWhenyoubuildadipoleantenna,cutitacoupleofpercentagepointslongerthanthecalculatedlengths.However,becauseofitsreducedphysicalsize,thistypeofloopexhibitslowradiationresistance,afactthatmakesRFtransmissioninefficientunlesstheconductorshaveminimalloss.BasementWheneverI’velivedinafull-sizedhouse,I’velocatedmyhamradioequipmentinthebasement.Ifyouwanttoknowwhichpartoftheearthliesinsunlightandwhichpartliesindarknessatanyparticulartime,doanInternetsearchonthephrase“GreyLineMap”(notetheBritishspelling).Setyourcomputertoworkwithanexternalmicrophone,nottheinternalone.YagiAYagiantenna,whichradiohamssometimescallabeamantennaorsimplyabeam,comprisesanarrayofparallel,straightantennaelements,withatleastoneelementactinginaparasiticcapacity.TheoriginaldesignwasdevelopedbyRCA(RadioCorporationofAmerica),andworkswellinhi-fireceiversandintheaudioportionsofold-fashionedanalogTVreceivers.I’vesatisfiedmyselfthatthecoldwaterpipeconnectsdirectlytothemainelectricalgroundforthehousebyperformingacontinuitytest.InPSKandothernon-CWdigitalmodes,youshouldalwaysrespondtoastationpreciselyonitsfrequency,whetherornotit’sDX.Anopen-wireline,especiallyifit’smadewithlargediameterconductorsandhasmostlyairasthedielectric,canworkefficientlyeveniftheSWRis10:1oreven15:1!Asamatteroffact,ifyoucangeta2:1orbetterSWRatthefeedpointwherethelineconnectstotheantenna,you’llexperienceapowerlossfigureoflessthan1dBcausedbythemismatch.Unlessyou’reinaremotelocationfarawayfromtheutilitygrid,youshouldseeverticallinesofvariouscolors.Warning!ThesecondtypeofLFandVLFlisteningantennaincommonuse,thesmallloop,worksaccordingtotheprincipleof“grabbingthemagneticcomponent”oftheEMfield.FIGURE5-6AtA,ahalf-waverectifiercircuit;atB,afull-wavecenter-taprectifiercircuit;atC,afull-wavebridgerectifiercircuit.Geier,Michael,HowtoDiagnoseandFixEverythingElectronic.ForTechiesOnlyUnfortunately,eventhebestsuperheterodynereceivercaninterceptorgenerateunwantedsignals.Ifthere’salotofenergy,thelinebecomesorangeorred.Checkthemoutatwww.palstar.comOneofthePalstartransmatchesgotafavorablereviewinQSTMagazine,theofficialARRLpublicationforhams.AllocationsbyModeAmateurRadiooperatorsmaylegallyuseonlydigitalanddatamodesbetween21.000MHzand21.200MHz,includingCW,RTTY,PSK,MFSK,data,andsimilaremissions.Undersomeconditions,you’llencounterafrequencyatwhichcommunicationdeterioratestothepointofuselessness.ExamplesincludetheYagiantennaandthequadantenna.WithmyIcomIC-746Procutbackto7wattsoutput,Ineednotfearoverstressingthefinalamplifier,evenifItransmitalldaylong.Obviously,youmustremoveorcollapsesuchanantennawhiledrivingthevehicle,butwhenit’sparked,anythinggoes!TipArandomlengthofwire(thelongerthebetter)withanantennatuneratthetransmitteroffersagreatoptionforheavyportableinstallations,providedyoucangetagoodgroundfortheantennato“workagainst”andcanfindsomethingtosupportitsfarendareasonabledistanceabovetheearth’ssurface.AnOldTimerRemembers(Not!)Idon’trecallthecomponentvaluesortheschematicdiagramforthatlittleregenerativeshortwaveradio;thekitprovidedonlypictoriallayouts.Otherwisethetransmitterwilloverloadthereceiver.Atfullspeed,ahamradioMFSKsignalmovesalongatabout42wpm,averagedovertime.Butmaybethat’soneofmymanyold-schoolhang-ups.FIGURE7-3Basicquarter-waveverticalantennas.Asyouincreasethedeviation,additionalsidebandsappear,fartherawayfromthecarrierfrequencythantheonesthatyouwouldseewithAM.RelativeFrequencyTheseconddistinctionbetweenCWandnon-CWdigitalmodesliesinthechoicesofrelativefrequencyduringcommunications.Theresultisreduceddynamicrange(differencebetweentheloudestandthesoftestvoiceinputlevels),buttheintelligibilitycanimprove,especiallyundermarginalcommunicationsconditions,becausethesignalcarriesextra“heft.”Thepeakpowerdoesn’tincreasecomparedtoasignalwithoutcompression,buttheaveragepowerdoes.Ifyoudon’tliveintheUnitedStates,checkwithyourgovernmentauthoritiesbeforeyougetinvolvedwithSWLorAWL.6-2).Inanycase,asageneralrule,BPSK31signalsalwaysgointhedigital-onlysectionsofthehambands.Youcanobtainfour-element,five-element,orlargerYagisbyplacingextradirectorsinfrontofathree-elementYagi.Onlylidscallotherhamslidsontheair.You’lllearnhowanysortofdatacanbe“imprinted”onradiowavessothatinformation,andnotmerelyelectromagneticfields,canpropagateovergreatdistances.I,forone,havetroublewithrogueneighborhoodelectricalappliancesonthisband.Imaginethatyouconnectatransmittertoanantennaandtestthewholesystem.7-2B.Forexample,if60Hzisthefundamentalfrequency,thenharmonicscanexistat120Hz,180Hz,240Hz,andsoon.Removeanyexistingexternalscreenorstormwindow.ButIfinishedthecoursesomehow,andgotmyNoviceClassLicense.Withyourreceiver’sproductdetectorswitchedon,shortwavebroadcaststationsdefinethemselvesasaloudcarrierwith“gibberish”superimposed.Asaresult,whenyouhaveawireseveralwavelengthslong,yougetacomplexradiationpattern;asthelengthgrows,sodoesthecomplexity!BroadsideArrayFigure7-9showsthegeometricarrangementofabroadsidearray.VisitMFJontheWebatwww.mfjenterprises.comNeverforgettodisconnectyouroutdoorantennafromyourradiowhenyouaren’tusingtheradio.Inafewcases,hamradiooperatorsandseriousradiohobbyistshaveseentheMUFgetupto70MHzorso!Thenumberofsunspots,averagedoverperiodsofafewdays,correlateswiththesolarflux,whichdirectlyaffectsthedegreetowhichtheupperatmospheregetsionized.Continuinginward,circlesrepresent10dBdown(−10dB),15dBdown(−15dB),and20dBdown(−20dB).Ineverletmydesireforagoodtimetrumpmydesiretoremainhealthyandalive!FIGURE6-4TheW1GVmobileCWinstallation,showingtheradioandSWRmeterinthebackgroundandthekeyerpaddleintheforeground.AnOldTimerRemembersIn2004whenIfirstgotinterestedinPSK,IboughtaninterfaceboxcalledtheRigBlasterProfromWestMountainRadio.Butthere’saglitch:Whenyouemployso-calledphasemodulation(PM)withtheintentofgettinganFMsignal,youmustprocesstheaudiobeforeyouapplyittothemodulator,adjustingthefrequencyresponseoftheaudioamplifiersbyexperiment.YoucantunetheLOtoobtainanaudionoteatacomfortablelisteningpitch,usually500to1000Hz.Thisprocessiscalledheterodynedetection.TheideaofcommunicatingwithotherpeopleoverlongdistanceswithoutanyartificialinfrastructuretocarrythesignalshasmesmerizedmeeversinceI,fiveyearsoldinthelate1950s,satatthekitchentableinfrontofatubedrivenradioandsaid“Calling!Calling!”intothespeaker.Whiskeyonegolfvictor.Insomecoaxialcables,asolidorfoamedpolyethylenelayer,calledthedielectric,keepsthecenterconductorrunningrightdownthecentralaxisofthecable,asshowninFig.Asyoureducethefrequencyandincreasethewavelength,youobservedecreasinggroundloss,andthewavescantravelprogressivelygreaterdistancesbymeansofsurface-wavepropagation.Themechanicalsystemwouldn’tletyoupoundoutcharactersatarateanyfasterthanthemaximum60wpm.Iwasinthethirdgrade,andevenasIwritethischapter,IhaveanotethatIwrotetomyselfthatyear(1963),statingthatIintendedtobecomeanAmateurRadiooperatorbythetimeIturned10yearsold.Asthemismatchbetweenthelineandtheloadgetsworse,theSWRgoesup.IfyouwanttouseananalogtelevisionsettodisplaySSTVimages,you’llneedascanconverter.AlargeAmateurRadiotransmitterorlinearamplifierneedsmorecurrent.However,colorimageshavebeensuccessfullysentandreceivedonallthebandsonwhichimagetransmissionisallowed.•Longwavecoverageletsyoulistenallthewaydownto100kHz,30kHz,oreven10kHzinsomeradios.TheradiowouldscanthebandbetweenlimitsthatIcouldpreset,andthensearchforanoccupiedchannel.OperatinginCWSincetheeliminationoftheMorsecoderequirementforobtainingahamlicense,CWoperationhasdeclined.Theyworkedentirely(oralmostentirely)withvacuumtubes.Butwhataboutsomeoftheothersignalsyouhear?Thefeed-pointradiationresistanceequalsapproximately73ohms,thesameasthatofahalf-waveopendipole.Thetermsynchronizedcommunicationsreferstoanyofseveralspecializeddigitalmodesinwhichthetransmitterandreceiveroperatefromacommonfrequency-and-timestandardtooptimizetheamountofdatathatcanbesentinacommunicationschannelorband.CheckItAgain!InthesituationofFig.And,ofcourse,youshouldkeepthecordasshortaspossibleandmakesurethatithasthreeconductors.•Chapter7describespopularhamradioantennasandtransmissionlinesforvariousfrequenciesandstationtypes.FIGURE5-16Here’swhatignitionorimpulsenoiselookslikeonanoscilloscopedisplayconnectedintoaradioreceiver.WithQRP,youcangetawaywithreceive-gradecapacitorsandinductorsifyouwanttobuildantennatuners.IfanFMsignal’sbandwidthdoesnotexceedthatofastandardAMsignalhavingthesamewaveform,engineerscallitnarrowbandFM(NBFM).However,somepeoplehavemadeQSOsoverconsiderabledistancesusinglessthan1wattallthewaydownto1.8MHz.TechnicalAdvantagesofQRPWhenyouoperateQRP,youcanusebatterypowertorunyourstation,andyourbatterieswon’tbefivetimesasheavyasyouare.Atnight,you’llhearsignalsfromallovertheworldandatalltimesoftheyear.Thetrickliesinmakingsurethatthe“noiseantenna”picksuplotsofnoisebutlittleornosignal,andensuringthatitsoutputcanbeadjustedsothatitperfectly“bucks”thenoisepickedupbythemainantenna.Inmymindandmemory,the10-meterbandearneditsreputationasamagicbandonthatday!HowDoTheyLook?Sotheycan,iftheylearntohuntwell,gathermoresectionsthantheirmorepowerfulcounterpartswhomustsnaretheircontactsastheycome,fromwherevertheycome.Unfortunately,inamobilestationatawavelengthlongerthan12or15meters,agoodgroundsystemisallbutimpossibletoattainunlessyou’repilotingabigtruck,atrain,anaircraft,oralargeboat.Youcanseethethirdharmonicat2067Hzasaprominentpip.TheARRLofficialstationW1AWnolongersendsitsnon-CWdigitaltextbulletinsinAMTOR;asofthiswriting,theyuseMFSK16,PSK31,andconventionalBaudotRTTYinarotatingsequence.Myadvicehereissimple:Getagoodgeneralcoveragereceiver,setupagoodantennaasdescribedlaterinthischapter,andstartlistening!ASimpleAntennaforSWLIfyoubuyacommerciallymanufacturedshortwaveradio,especiallytheportabletypethatseemstoprevailthesedays,itwilllikelyhaveitsownantennaattached:awhipthatextendstoaboutonemeterinlength.Icheckeditoutonanafternoonwithexcellentreceptiontakingplaceonthe16-meterand13-metershortwavebandsaswellasonthe15-meterhamband.EventhoughIneverparkedmyvehicleanywherenear33metersfromthestation,Ididn’twanttocutintothatcableforfearoflong-termwaterintrusion,soIcoileduptheportionofcablethatIdidn’tneedandsetitinthetruckbedneartheantenna.FIGURE1-8AnamplitudemodulatorusinganNPNbipolartransistor.Forexample,thesignalantennamightbeatallverticalelementoperatingagainstanearthground;thenoiseantennacancompriseashort,randomlengthofwirerunonthefloorinsideyourhouse.InformationcontainedinthisworkhasbeenobtainedbyMcGraw-HillEducationfromsourcesbelievedtobereliable.FIGURE5-11“Tanglewiregarden”beneaththeauthor’selectronicsworkbench.Waitahalfminuteorso,andthenrepeatyourCQifnobodyanswers.Sometimesyouwantacircuittobenonlinear!AudioFilteringInacommunicationssystem,ahumanvoicesignalrequiresabandoffrequenciesrangingfromabout300Hzto3000Hzforalistenertoeasilyunderstandthecontent.Alongwithnoisefromthesun,theplanetJupiter,andafewothercelestialobjects,galacticnoiseaccountsformostofthecosmicnoisearrivingatthesurfaceoftheearth.Ifitlooksclear,askifthefrequencyisinuse,andidentifyyourstation,likethis:Isthefrequencyinuse?Onceyou’vefinishedtransmitting,waitafewseconds,andiftheotherstationdoesn’trespond,transmityourofferagain,exactlythesameasyoudidthefirsttime.JPoleYoucanorientazeppantennavertically,andpositionthefeedlinesothatitliesinthesamelineastheradiatingelement.Therepeatertransmittercan,andoftendoes,havemuchhigherRFpoweroutputthanahamradiooperator’sowntransmitter.•You’llfindplentyofrepeateractivityonVHFandUHF,especiallyon2metersand70centimeters,andthesesystemsoffergreatconvenienceaslongasyouknowthetonesquelchfrequencyforeveryrepeaterthatyouwanttouse.IfyouoperateCWforawhile,you’llgrowfamiliarwiththem.Ifyoudon’tknowexactlywhataYagiisandyoucan’twaittofindout,flipaheadinthebookandglanceatthemnow,andthendigintothedetailslater.Intheearlydaysoftelegraph,operatorsusedaslightlydifferentcodeknownastheAmericanMorsecode.HeadsUp!Dependingonwhereyoulive,youmighthavetoadheretospeciallimitationsonoperatingfrequenciesandmaximumoutputpower.Resistthattemptation.Auroralpropagationusuallytakesplacealongwithpoorionosphericpropagationresultingfromsuddeneruptionscalledsolarflaresonthesun’ssurface,soifnormalpropagationsuddenlydeteriorates,youmightwanttocheckforauroraeffects!MeteorScatterPropagationAsmeteoroidsfromspaceentertheearth’supperatmospheretobecomemeteors,theyproduceionizedtrailsthatpersistforafractionofaseconduptoseveralseconds.Atnight,theDlayerdisappears,andyoucanexpectworldwidereceptionfromstationsthatusehighRFoutputpowerlevels(severalkilowattsormore).AllocationsbyLicenseClassExtraClassoperatorscanusethewhole20-meterband,subjecttomoderestrictions.AmateurRadiooffersallthosehardwareoptionsandmore,intheformofmobileandportableequipment.Anotherprogram,calledHamScope,workswelltoo.DidYouKnow?Individualreceiverdesignsvary,butyoucanconsiderthisexamplerepresentative.Mosttwinleadlineshaveacharacteristicimpedanceof300ohmswhendry,andwhennotrunnearconductingobstructions.Theexactdurationofanygivenmeteortraildependsonthesizeofthemeteor,itsspeed,andtheangleatwhichitenterstheatmosphere.OntheVHFandUHFhambands,asmallerproportionofthetotaloperatorsuseSSBthanisthecaseontheHFbands.Youcanthinkofthiscircuitasanamplifierwhosegain(amplificationfactor)dependsonthevoiceinputlevelfrominstanttoinstantintime.Resonancecanbeobtainedbymeansofatransmatch(antennatuner)atthefeedpoint,eveniftheloopitselfdoesnotexhibitresonanceatthefrequencyofinterest.SetyourmultimetertomeasurethehighestACvoltagethatitcandealwith.OtherShortwaveActivityOfcourse,you’llfindplentyofotheractivityontheshortwavefrequenciesbesidesinternationalbroadcastingandhamradio.Thecharacteristicimpedanceofanair-dielectricbalancedlinedependsontheradiusoftheconductors,andalsoonthespacingbetweentheconductors.Theprospectofcommunicatingwithhandheldandmobileradios,alongwithrepeaters,hasprobablybeenthegreatestfactortomotivateoldNovicestobecomeTechs!AnOldTimerRemembersDuringmyNoviceyearin1966–1967,thespanfrom145.000MHzto147.000MHzformeda2-meterallocationforthatclass.FIGURE3-12AtA,theprincipleofrepeateroperation.ReadingandCopyingItIfyouwanttolearnthecodeandboostyourskillonceyouknowthecharacters,you’llfindnosubstituteforpractice—hoursandhoursofit!TheofficialstationoftheAmericanRadioRelayLeague(ARRL),bearingthecallsignW1AW,sendscodepracticesessionsregularlyonsomeoftheHFhambandsatspeedsrangingfrom5wpmto35wpm.Thesquelchopens,allowingeverythingtobeheard,ifthesignalamplitudeexceedsasquelchthresholdthattheoperatorcanadjust.•Imagerejection—Inapoorlydesignedreceiver,you’llhearlotsofphantomsignals,calledimages,onfrequencieswheretheyreallyaren’ttransmitting.Ifallofthemagneticlinesoffluxareperpendiculartotheaxis,thewaveguideisoperatinginthetransverse-magnetic(TM)mode.YoucanimaginethiscircuitasanRFamplifierforthecarrier,withtheinstantaneousgain(moment-to-momentamplificationfactor)dependentontheinstantaneousaudioinputamplitude.Becauseitsomewhatresemblesarectangle,engineerssaythatthereceiverhasarectangularresponse.YoucanconsideralongwireasasortofphasedarraybecauseitcontainsmultiplepointsalongitsspanwheretheRFcurrentattainsmaximumvalues.However,awell-engineeredgeneratorwithapowerinverter,eventhesmallgasoline-fueledtype,willworkfinewithcomputers,microcomputer-controlledhamradios,andothersophisticatedsystems,aslongasyoukeepitinproperworkingorderanddon’toverloadit.7-6.Dual-diversityreceivertuningisasophisticatedtechnology(youmightcallitanart),andgoodequipmentforthispurposecostsalotofmoney.Agooddummyloadisalsoagreatadditiontotheexperimenter’srepertoire!10MetersIfyou’vehadexperiencewithCitizensBand(CB)radios,youshouldhaveagoodideaofhowthe10-meterhambandtreatssignals.ThetransmitterhastoworkhardertoproducenegativePAMthanitdoestoproducepositivePAM.Physically,atransmission-linewaveguidecomprisesahollowmetalductorpipe,usuallywitharectangularcrosssection.And,forthosefolkswhoinsistonsendingtheirtextinalluppercase(astheoldBaudotcodedidbydefault),thepracticalspeedwithPSKturnsoutcloserto30wpm.Athree-elementquadhasonedrivenelement,onedirector,andonereflector.Sendtheotherstation’scallonce,followedbyyoursonce,twice,orthreetimes,dependingonhowwellyouthinktheotheroperatorwillhearyou,anddependingonthelengthand“CWfriendliness”ofyourcallsign.aslongasyouexpressranddinthesameunits,suchascentimetersormillimeters.HowFast(orSlow)DoesItGo?NearlyallactiveelectronicdevicesrequireDC.Today’slinearshavefeaturesthatmakethemversatileindeedcomparedtotheir“boatanchor”ancestors!Theseattributescanincludebuilt-inwattmeters,built-inSWRmeters,provisionsforfullCWbreak-inoption,automaticshutdownincaseofoverheating,automaticgaincontrol(AGC),andautomatictune-uporbroadbandoperation.First,theloadmustcontainnoreactance;itmustcompriseapureresistance.Findamapthat’scenterednearyou.Ifyouinjectanaudiosignalthat’stoostrong,you’llendupwithdistortion(nonlinearity)inthetransistor,resultingindegradedintelligibility(understandability),reducedcircuitefficiency(ratioofusefulpoweroutputtototalpowerinput),andexcessiveoutputsignalbandwidth(thedifferencebetweenthehighestandlowestsignalfrequency).Motorists,hikers,boaters,andsmall-aircraftpilotsusetheseradiostocallforhelpwhenstranded.AmateurRadioisintendedfornon-profitactivitiesonly.Someoftheprivilegestakenawayduringtheincentivelicensingdayshavebeenrestored.Studythemandthengogetthatlicense!GeneralAfteryou’veheldaTechlicenseforawhile,you’llprobablywanttoupgradetotheGeneralClasslicense.Ingeneral,ifawavehasafrequencyequaltontimesthefundamentalfrequencywherenissomewholenumber,thenthatwaveiscalledthenthharmonic.(You’llreadmoreaboutwaveguideslaterinthischapter.)Hornsaresometimesusedallbythemselves,buttheycanalsofeedlargedishantennasatUHFandmicrowavefrequencies.•Semibreak-inoperationinCWactuatesthetransmitterautomaticallywhenthekeyisclosed;thereceiverisdisabledwithadelay.LookforBPSK31activityinthefollowingfrequencyranges:•160meters:1.838MHzto1.841MHz•80meters:3.580MHzto3.583MHz•40meters:7.035MHzto7.038MHzand7.070MHzto7.073MHz•30meters:10.140MHzto10.143MHz•20meters:14.070MHzto14.073MHz•17meters:18.100MHzto18.103MHz•15meters:21.070MHzto21.073MHz•12meters:24.920MHzto24.923MHz•10meters:28.120MHzto28.123MHzOccasionallyyou’llhearasignalthat’salongwayoutsidethesezones,andpeopleoftenstrayslightlyaboveorbelowthem,especiallyon40metersand20meterswhenactivitygrowsheavy.TheNoviceClasslicenseconveysrestrictedCWprivilegesonafewoftheHFbands,alongwithsomeRTTY,data,andSSBprivilegeson10meters.TheTechnicianClasslicensetestisfairlyeasy.On25meters,you’llnoticeabigimprovement,comparedwiththelower-frequencybands,inreceptionoverpathsthatlieentirelyonthesunlitsideoftheearth.FIGURE3-8BHamScopedisplayoftheMFSKtuningmethodcalledthewaterfallmode.Thepositionofthepipalongthehorizontalaxisindicatesitsfrequency.Other,moreexoticdigitalmodesarealsoallowed.TheatomiccharacteristicsofwireormetaltubingcauseEMfieldstotravelalongareal-worldconductoralittlemoreslowlythanlightpropagatesthroughfreespace.Duringthedaytime,youmightfindcasualcommunicatingorDXingnighimpossibleon20,15,andperhapseven10meters.You’llsuffersomelossinthefeedlinewhenyoutakeadvantageofthistrick,butitwon’tamounttomuchbecauseinmobileapplicationsthefeedlineisshort,andtherefore,thelinewillhavelowlossevenifit’snotwellmatchedtotheantenna.•Setyourreceiverandtransmittertothesamefrequency.Thenyouhaveadouble-conversionreceiver.The60-,30-,17-,and12-meterbandsrarely,ifever,hostcontestevents.Theeffectoccursdayandnight,eventhoughthe“lights”canonlybeseenvisuallyatnight.TheacronymASCIIstandsforAmericanStandardCodeforInformationInterchange.Therefore,±5kHzismorethanenoughdeviationforvoicecommunications.2-7)canreceivesignalsdownto30kHzandalsoupto174MHz,afrequencythatlieswellintotheVHFpartoftheradiospectrum.Astheamountofelectricalpowerdemandedfromageneratorincreases,sodoesthemechanicalpowerrequiredtodriveit,andtherefore,theamountoffuelconsumedperunitoftime.IstillcopysomecodeeverynowandthentoseeifIcanputdownasolidminuteofcharacters,error-free,at20wpmafteralltheseyears.Ifyouspendacoupleofminutestuningthrough,say,the10-meterCWbandandyoudon’thearanything,youshouldn’tconcludethatthebandis“dead”untilyousendafewCQstoseeifanyonecomesbacktoyou,andhavetunedaroundandlistenedforagoodquarterofanhour.Speakclearlyatamoderatepace.Figure1-18Ashownasimplifiedtime-domainviewofhowthisprocessworks.TheARRLcanprovideyouwithmoreinformation.FIGURE7-8AtA,aunidirectionalend-fireantennaarray.Pulse-AmplitudeModulationYoucanmodulateasignalbyvaryingsomeaspectofasequence,ortrain,ofsignalburstscalledpulses.Thenarrowbandmodesgotmorespectrumspacethanthewidebandmodesgot!Thatstateofaffairsseemsbizarrebytoday’sstandards,doesn’tit?•ContacttheARRL’sAmateurRadioEmergencyService(ARES)andtellthemthatyouwanttogetinvolved,andwouldlikespecificinstructions.Anotheralternativeistheground-planeantenna,essentiallyaquarterwaveverticalwiththreeorfourquarter-waveradialsandwithitsbaseelevatedatleastaquarterwavelengthabovetheearth’ssurface.10Aand10Bshow.Inreceivingapplications,verticallyorientedantennas“pickup”morehumanmadenoisethanhorizontalantennasdo.Thedielectricisalmostentirelyair.Thegreatertheradiationorreceptioncapabilityoftheantennainacertaindirection,thefartherfromthecenteryoushouldplotthecorrespondingpoint.Popularperipheralsincludelinearamplifiers,transmatches(alsocalledantennatuners),anddigitalinterfaceequipment.FIGURE2-13Dirtyelectricityinmyworkspace,asviewedonDigiPan.Chirpandmusicalmodulationdon’toccurofteninlatter-dayequipment,butI’veheardbothproblemsontheairasrecentlyas2013.Themostimportantconsiderationisthatyourwiresitupintheclear,awayfromobstructions,andthatyouavoidplacingitinsuchawaythatitcanfallorblowdownonanelectricutilityline,orthatanelectricutilitylinecanfallorblowdownonit.Theseabbreviationsresemblethejargonusedincell-phonetexting,andinsomecases,thetwoareidentical.Buttheformalsign-offsymbolistheSKcombo,di-di-di-DAH-diDAH.Humanmadenoisepresentsadifferentconundrum.NewYork:McGraw-Hill,2011.Two-WayErrorCorrectionWhenatwo-waycontact(orQSO)isestablishedbetweendifferentstations,AMTORswitchesovertotheARQmodeoferrorcorrection,whichsomeengineerscallbackwarderrorcorrection(BEC).IuseDigiPan’sexcellenthigh-definitiontuningaidtoseewhereCWsignalsresidewithinmyreceiver’spassband,soIhavethetextscreenandcontrolbardisabled.Thissituationoftenexistsforextremelyshortantennaradiatorsbecausetheyexhibitlowradiationresistance.Youcancategorizetheseradiosaccordingtotheirfrequencycoverage.Basically,anSSBsignalisanAMsignalwiththecarrierandonesidebandremoved,andthenfilteredsothatthebandwidthislimitedtoalittlelessthan3kHz.Inmostradiosthesedays,theaudioinputisfilteredforapassbandthatrangesfrom300Hzto3kHz,sothepracticalbandwidthis2.7kHz.Then,inadditiontotheaudiofiltering,theRFstagesofthetransmitterincorporateasecondbandpassfilterintheIFchain.DoyouwanttouseCW,RTTY,DigiPan,SSB,FM,oroneofthosenewandexoticmodes,suchasMFSKorWSJT?InCW,transmitatareasonablespeedsothatyouneedsendyourcallandexchangedataonlyonetime.Ifyouwantyourgeneratortoworkwhenyouneedit,youmustadheretoamaintenanceschedulethatinvolvescleaning,spark-plugreplacement,andperiodictesting.7-1A.Aslongasit’s2:1orless,youshouldnothaveanytrouble.WorkingDXOneofthemostintriguingaspectsofhamradioisthefactthatyoucancommunicate,independentlyofhumanmadeinfrastructures,withpeopleallovertheworld.ThenoisefiguremakesthemostpracticaldifferenceatVHF,UHF,andmicrowavefrequencies.5-14,itwouldbelikeseatingallthepassengersonthelefthandsideofanaircraft.However,goodgrounding,bothforRFandforelectricalsafety,isadvisableforanyantennasystemtominimizeinterferenceandhazards.7-6A.Band-rejectionfilterspasssignalsonlybelowacertainlowercutofffrequencyoraboveacertainuppercutofffrequency.MosttransceiversforHFcanworkallpopularmodesincludingCW,SSB,AM,FM,andthevariousdigitalmodesbymeansofaudiodatasuppliedtothemicrophoneinputwhenyousettherigtoworkonSSB.Thespacesbetweendotsanddasheswithinasinglecharacterareonebitlong.•Chapter4coverstheassignedfrequencyranges,calledbands,thatlicensedhamsuseintheUnitedStates.Theymusthaveconsiderablebulkbecauseofthenumberofturnsinthesecondary,andalsobecausehighvoltagescanspark,orarc,betweenwireturnsifthewindingsaren’tspacedfarenoughapart.Afterdeployinganohmmeterbetweenvariouspairsofpointstomakecertainthatthegroundcontinuityprevailedthroughouttheentiretruckbody,Ifeltgoodtogo,butasofthiswriting,hadnotyettestedthesystem,excepttoverifythatitwillindeedtuneon15metersandallowmetocontactRussiawith25wattsoutputfromasupermarketparkinglot!I’llrelatetheperformanceofthisantennaonmyYouTubechannel,probablyinthe“AmateurRadio”playlist.Therestoftheband,from50.100MHzallthewayupto54.000MHz,isopentoallmodesofoperationthathamscommonlyuse,withtheexceptionoffast-scantelevision.(Ifyouuseacoppergroundrod,thebestkind,makesureitisn’ttooclosetotherootsofanytreesorshrubs.PolarizationYoucandefinetheorientationoftheelectric“linesofforce,”technicallyknownasfluxlines,asthepolarizationofanEMwave.Tosomeextent,theyoverlap,althoughhamradiostandsabovetheothertwointermsof“fascinationpotential”(inmyopinion).•YoucantakeyourDCpowerfromacigarettelighterwithanadapterplug,suchastheoneshowninFig.CHAPTER2ShortwaveandAllwaveListeningThefrequencyrangefrom3MHzto30MHz(wavelengthsof100metersto10meters)issometimescalledtheshortwaveband.ExtraClassoperatorscanuseallthebandsfromtoptobottom,includingthisone.ThisfeatureisespeciallypopularamongcontestersandDXersontheHFbands.SpecificationsThespecificationsofareceiverquantifyhowwellthehardwarecancarryoutthetasksthatitsengineersdesignedandbuiltittodo.Themostcommonmethodsarefrequencydivisionmultiplexing(FDM)andtime-divisionmultiplexing(TDM).TestforDCvoltageinbothdirections:firstwiththeblackprobetipinthe“thirdhole”ofthecordoutletandtheredprobetipinthe“thirdhole”oftheoutletundertest,andthentheotherwayaround.Seetextfordiscussionofspecificdimensions.Ifyouhavenoexperiencewithshortwavelisteningandwanttoexplorethathobbywithoutgettingahamradiolicense,thisbookofferstipsandadvice.Enter“VLFconverter”intothephraseboxofyourfavoritesearchengine.Thatsubjectmustremainatopicforsomefuturebook!APPENDIXASchematicSymbolsAPPENDIXBQSignalsforHamRadioThesesignalsareusedmainlybyCWoperators.Thistypeofcircuitcanbeextremelyeffectiveagainstignitionnoiseinsomecases,butdoesn’tdomuchfor“thunderstormstatic”orsomeformsofelectricallinenoise.•Adjustthetransmittertuningandloading(ifyourtransmitterhassuchcontrols)totheapproximatesettingsforthefrequencythatyouwanttouse.AtA,atunerforlowimpedanceunbalancedloads;atB,atunerforhigh-impedanceunbalancedloads;atC,atunerforlow-impedancebalancedloads;atD,atunerforhigh-impedancebalancedloads.That’salotofbands,butasyou’llseealittlelaterinthischapter,it’snotaverybigchunkofthespectruminabsoluteterms!Wherewillyoufindyour“niche”inthisrealm?•SloppysendingonCW.PersonalRewardsofQRPOperatingAfteryearsofQRPoperation,I’veevolvedtoenjoythechallenges,notsufferfromthelimitations!Ifyouhaveastackedpairof4-elementYagison20meters,oneat60feetandtheotherat120feet(asW1AWdidwhenIworkedthereinthelate1970s),alongwithafull-legal-limitamplifierandatop-ofthe-linetransceiver,youcanalmostalwaysworkanythingyoucanhear.Ahalf-wavedipolefor12metersspansroughly5.7metersfromendtoend;ifyoucutitfor24.940MHzatthebandcenter,you’llgetagoodmatchto50-ohmor75-ohmcableoverthewholeband.Youcanlaytheradialsrightdownonthesurface,orburythemafewinches(orcentimeters)underground.Theword“Paris”plustheseven-bitpausehasatotalof50bits,so1wpmworksoutto50bitsin60seconds,or5/6bitspersecond(5/6bps).Amateur-Radiopacketcommunicationsiscalledpacketradio.Itcameaboutintheearly1800swhenengineersperfectedthewiretelegraphandcouldsendonlysimplecurrentpulsesalongthelines.Thedisplayattheupperleftindicatesoptimumtuningwhenthetwosignalpeakscoincidewiththeverticallines.ACWorFSKsignalrequiresonlyafewhundredhertzofbandwidth.Inacoaxialcable,thesignaliscarriedbythecenterconductor.Then,whenyourespond,theDXstationwillclearlyhearyoubecauseyourstation’ssuppressed-carrierfrequencywillbezerobeatwiththeDXstation’ssuppressed-carrierfrequency.Theeffectiverangeatnightgreatlyexceedstherangeduringthedaybecausewhenthesunisabovethehorizon,theionosphere’sDlayerabsorbsradiowavesatthisfrequencybeforetheycanreachthehigherlayers.Ononeoccasion,Iaccessedarepeaterandhelpedafamilywhosecarhadbrokendownatnightinthecountry.Ifyou’reworkingSSBandyouwanttoworkDXinsingle-frequencymode,tuneintheDXsignaluntilthevoicesoundsnatural,andthenmakecertainthatyourradioisnotsetforanysortofincrementaltuning,suchasreceiveroffset(alsocalledclarifier)ortransmitteroffset.Butinpulse-intervalmodulation(PIM),pulsescanoccurmoreorlessfrequentlythantheydounderconditionsofnomodulation.15.Agoodelectricalgroundalsominimizestheriskofelectromagneticinterference(EMI)toandfromradioequipment.Eachverticaldivisionrepresentstwoordersofmagnitude(twopowersof10).Somecombustiongeneratorsarealsosuitableforusebycampers.Asofthiswriting,Ifoundagoodgrey-linemap,whichrefreshesitselfeveryfiveminutesifyoukeepyourcomputerconnectedtotheInternet,atdx.qsl.net/propagation/greyline.htmlRememberthatshortwaveradiosignalsusuallyfollowtheshorteroftwogeodesicarcsaroundtheplanetastheypropagatebymeansoftheionosphere.TipIttakesmoreworktoplaytheroleofthehunterthanitdoestoplaytheroleoftheprey,buthuntershavemorecontroloverwhomtheycontact.Forexperimentersandtechnophiles,it’saneatslotbetweenthelarger,morecrowded,andfrequentlycontest-cluttered20meterand15-meterbands.Whiletheaudioqualityofthesedevicesisdecent,it’snotperfect.Theothertypeofkeyerusesakeyboard.ForNerdsOnlyThe2800-MHzsolarfluxcorrelateswiththe11-yearsunspotcycle.FIGURE5-12Blockdiagramofthe“tanglewiregarden”beneaththeauthor’sworkbench.IuseaninterfaceboxcalledtheRigBlasterPro,manufacturedbyacompanycalledWestMountainRadio,betweenmycomputerandmyradio.Moonbouncehasgainedconsiderablepopularityon70centimeters,andsomehamsdoiton23centimetersaswell.Also,sfericscanpresentaprobleminregionsoftheworldwherethunderstormsoccur,andinmostcases,that’sspringtimeandsummertime.Ifthere’salittlebitofenergyataparticularfrequency,you’llseeathin,verticalbluelinecreepingstraightdownward(ifyouleavetheprogramsetforitsdefaultcolorscheme).Thatway,youwon’tscareawaypotentialcontacts.11.ParasiticArraysCommunicationsengineersandradiohamsuseparasiticarraysatfrequenciesrangingfromapproximately5MHzintothemicrowaverangeforobtainingdirectivityandforwardgain.Soon,commercialentitiesandgovernmentstookinterestintheshortwaveband,andamateurslosttheirlegalrightstomostofit.Alternatively,youcanplaceafull-sizequarter-wavelengthverticalantennaonyourvehicleandrunalengthofcoaxialcablefromyourrigtoit.Thatmeansyou’llhavetouseatransmissionlinebetweenyourradioandyourantenna.TipClass-DCBradioequipmentdoesn’tcostmuch.Ineffect,theyamounttoCWsplatter,andtheycausethesignaltoviolateFCCregulations.Whenconditionsaren’ttoobad,FSKworksbetterthanon/offMorse-codestylekeyingfordatacommunicationsbecausethespacesignalsarespecificallyidentifiedthatway(inotherwords,theirexistenceisconfirmedbyanactualsignalratherthanbysilence).Nevertheless,thisbandisworthcheckingoutatanytime.Troposphericbendingcanallowyoutocommunicateforhundredsofkilometers,evenwhentheionospherewillnotreturnwavestotheearth.Also,atmosphericnoisetendstopresentlessofaproblem,soyoucangetgoodreceptionduringthespring,summer,andfallaswellasinthewinter.Allcoaxialcablesarefabricatedinthesameway:Awireissurroundedbyatubeorbraidofsolidorbraidedmetal.Front-to-BackRatioThefront-to-back(f/b)ratioofaunidirectionalantennaquantifiestheconcentrationofradiation/responseinthecenterofthemainlobe,relativetothedirectionoppositethecenterofthemainlobe.Whenyouwanttotransmit,youhitabuttononthecontrolbarthatsays“Rx,”anditwillgooverto“Tx.”Togobacktoreceivemode,hitthe“Tx”button.Henevertoldmewhereto“sail,”buthemadesurethatIhadgood“boats.”HeboughtmeasmallrefractingtelescopetocomplementhisownbigNewtonianreflector;Igotaprettygoodmicroscopeoneyeartoo.Thesameeffectoccursifthetwowavesarriveinvertedinphasewithrespecttoeachother(thatis,inphaseopposition).Thenumberandrelativeamplitudesofthesesidebandsisacomplexmathematicalfunctionofthedeviation,andalsoofthehighestaudiofrequencythatgoesintothetransmitter.Externalfalsesignalsarecalledimages;internallygeneratedfalsesignalsareknownasbirdies.DetectorsDetection,alsocalleddemodulation,allowsaradioreceivertorecoverthemodulatinginformation,suchasaudio,images,orprinteddata,fromanincomingsignal.FIGURE1-12BlockdiagramofabasicSSBtransmitter.WhenYouAretheDXFortheadventurousspirit,nothinginhamradiocansurpassthethrillofplayingtheroleofpreyinamassiveDXpileupbygoingonaso-calledDXpedition.Talkloudenoughsothatthetransmitter’spowerorRFoutputmeterkicksuptotheproperpoints.Don’tusefiltersthatfitintelescopeeyepieces;thefocusedsunlightcanheatthefilterglasstothepointwhereitbreaks,givingyourretinaahorrificjolt.Ithasa35-ampere-hourstoragecapacityandcandeliverthe22amperesnecessarytoruntheYaesuFT-857DatfullRFpoweroutput(100watts).Figure5-6Cshowsaschematicdiagramofatypicalfullwavebridgecircuit.TipIdeally,youshouldusealinearonlywhenthepoweroutputfromyourtransceiverisnotenoughtoprovidereliablecommunications.Ifyouhaveamultibandantenna,you’llhearabundantsignalsonsomebandsandfewornoneonotherbandsatanygiventime.Youcanseethisrelationifyouexaminetheconcentriccirclesintheplot,notinghowfaroutfromtheoriginthesidelobesextend,comparedwiththemainlobe.FIGURE6-9Theportablewhipantenna,almostfullycollapsed.Obviously,suchantennaconductorsdonotexistinphysicalreality.IthasanoutstandingadvantageoverRTTY,PSK,andMFSK:Youcanmaintainalmosterror-free,albeitsluggish,communicationsevenwhenlotsoffading,interference,ornoiseoccur,ifyou’rewillingtotakethehardwareandprogrammingstepsnecessarytoworkintheARQmode.Ifyouplantooperateamobilehamradiostation,checkwithstateandlocallawenforcementofficialsbeforedoingitwhilethevehicleisinmotion.Like10meters,thisbandcanseemmagical,openinguptotheworldwithionosphericpropagationeveryonceinawhile.Inacity,dirtyelectricitycanrenderVLFreceptionimpossible.Inaddition,voiceandimagemodeprivilegesareavailableon1.25metersat222to225MHz,andalsoon23centimetersat1.270to1.295GHz.TheTechnicianPlusClasslicense“morphed”intotoday’sTechnicianClasslicense.Thepotentiometerletsyouadjustthelevelofsignalsandnoisefromthenoiseantenna,whilehavingaminimaleffectontheoverallsignallevelfromthetwoantennascombined.Dynamicrange—Thesignalsatareceiverinputcanvaryoverseveralordersofmagnitude(powersof10)intermsofabsolutevoltage.FIGURE1-13Generationofafrequency-modulated(FM)signalbymeansofreactancemodulation.(ForQsignals,seeApp.Whentheinstantaneoussignalfrequencyrisesabovecenter,theoutputvoltagebecomesnegative.Whentheinstantaneoussignalfrequencyfallsbelowthepassbandcenter,theoutputvoltagebecomespositive.However,sufficientconcernexistsamongsomeexpertstowarrantcheckingthelatestpublicationsonthetopic.Multiplexingrequiresanencoderthatcombinesor“intertwines”thesignalsinthetransmitter,andadecoderthatseparatesor“untangles”thesignalsinthereceiver.Ifyousufferfromthissortofproblem,asIdofromtimetotime,consideraradio-frequencyinterference(RFI)solution.Handshaking,alsoknownasautomaticrepeatrequest(ARQ),isthebestwaytoensuredataintegrity,butit’sagonizinglyslowatthebandwidthsallowedontheHFhambands,anditrequiressomesophisticatedprogramming.Normally,ifyouwanttoreceiveRTTY,youshouldsetyourradiotolowersideband(LSB)mode.Direct-ConversionReceiverAdirect-conversionreceiverderivesitsoutputbymixingincomingsignalswiththeoutputofatunable(variablefrequency)localoscillator(LO).CommonFeaturesYoucanacquaintyourselfwithallthefeaturesavailableinmodernhamtransceiversbygoingtoahamfest(organizedconventionofhamradiooperators)andlookingatradios,orbyobtainingspecificmodelbrochuresfrommanufacturers.Insteadof(orinadditionto)usingatuningcapacitor,youcaninsertatunableRFpreamplifierbetweentheloopandthereceiver’sfrontendorantennainput.Whenyoucascadetransientsuppressors,they’lllikelyconflict.An“upsidedown”signalwon’t“print.”InmostMFSK16programs,youcandothatbyeitherhittingareversalbutton,orelseswitchingyourradioovertotheoppositesideband.AtVHFandUHF,animprovementinreceptioncansometimesresultfrommovingthetransmittingorreceivingantennaonlyafewcentimeters!Inmobileoperation,whenthetransmitterand/orreceivermove,multipledeadspotsproducerapid,repeatedinterruptionsinthereceivedsignal,aphenomenoncalledpicketfencing.Afull-wavelengthlooppresentsaradiationresistance(andzeroreactance,formingapurelyresistiveimpedance)ofabout100ohmsatthefeedpoint.Forsometime,thenoisesourceremainedamystery.OnSSB,say“Isthefrequencyinuse?AnOldTimerRemembersIftheframesyncina“vintageTVset”getsupsetforanyreason,thepicturewillroll,ormoveverticallyfromframetoframe.SmallCBradiosets,withreduced-sizemagnetic-mountantennas,areavailableformotorists,intendedforuseinemergencies.Thatpractice(alltoocommon,unfortunately)isnotonlywasteful,buttechnically,it’sillegal!SpecificFCCregulationsdictatethathamsshouldnotusemorepowerthantheyneedinordertocarryoutthedesiredcommunications.Allrightsreserved.Thisprocessslowsdownthetransmissionspeedandcausesthedatatoarriveinspurtsorburstsatthereceivingend.Iloved“pullingallnighters”onCWfromAssissiHeightsinRochester,Minnesota,swattingJunebugsinsomeyearsandworkingbetweenthundershowersinotheryears,sometimesfreezingandsometimessweating.Awell-designedpowersupplyhasdiodeswhosePIVratingssignificantlyexceedthepeakACinputvoltage.•Identifyyourstation.Thisschemewillsometimeshelpyouhearsignalsthroughnoisethatdefeatsastandardnoiseblanker.17MetersHamradiooperatorscanusethefrequencyspanfrom18.068to18.168MHz,commonlycalled17meters.ButevenifIhada1500-wattlinearandafour-elementYagiup100feet,IpersonallywouldneversendCQDX.TipSomedigitalcommunicationprogramsarepublishedasfreeware,meaningthatyoucandownloadandusethemasmuchasyouwant,andforaslongasyouwant,withoutpayinganything.Inthatcase,mostoftheappliedRFpower“goesinto”usefulEMradiation,andrelativelylittlepowergetswastedasheatintheearthandinobjectssurroundingtheantenna.Conditionspeakduringthewintermonths,especiallyatthehigherlatitudeswherethunderstormsdon’toccuroftenatthattimeoftheyear.HerearesomereasonstorunQRO(over25wattsoutput)inheavyportableapplications:FIGURE6-12Thedeep-cyclemarinebatterythatIuseforheavyportableoperation.Theauroraoccurataltitudesofabout60to400kilometers.However,theproblemisnotquitesosevereorextensivehereasitisonthoselowerbands.Thedataspeed(thousandsofbaud)exceedsthatofotherpopularhamradiodigitalmodes,allowingforthetransmissionoffairlylongmessages.IwouldsetthebandspreadtoaknownWWVfrequencyandthencarefullymanipulatethemaintuningdialtomakethesignalcomeinjustright.FIGURE6-11ABencherCWkeyerpaddle,glueddownwithcontactcementtoawoodenboardforportableoperation.NeitherMcGraw-HillEducationnoritslicensorsshallbeliabletoyouoranyoneelseforanyinaccuracy,errororomission,regardlessofcause,intheworkorforanydamagesresultingtherefrom.Ionosphericpropagationgoesawayentirely.W1GVTravelLogInFebruary2014,IacquiredaYaesuFT-857Dmobile/portabletransceiver(Fig.Lightningdischargeshavebeenknowntoinducecurrentandvoltagespikesinnearbyelectricalconductors,ofsuchmagnitudethatequipmentisdestroyedandfiresarestarted.Soifyouhearmesend“5NNSD”thenexttimeyoucontactmeinacontest,itmeans“599SouthDakota.”Contestersusethattacticallthetime,andDXersdoitalot,aswell.Ground-MountedVerticalThesimplestverticalantennacomprisesaquarter-wavelengthradiatormountedatgroundlevel.Andofcourse,inthenon-CWdigitalmodes,youdon’thavetoknowallthecodesymbols;inold-schoolCW,youneedpracticetogainproficiency.SomeofthosemodeshavethecapabilitytogomanytimesthespeedofconventionalRTTY,butsomeactuallygoslower.Figure2-11showsthisscheme.Thefirstfewprojectsinvolvedsimplebroadcastreceivers,suchasa“crystalset”thatworkedwithoutabattery,progressingtoabattery-poweredradiowithanaudioamplifierafterthedetector,andthenaddingothercomponentstoincreasetheselectivityandsensitivity.Ifyouwanttoforce-feedanantennawhosefeedlinecomprisessmall-diametercoaxwitha20:1SWR,goahead!Youwon’troastanythingwith5watts,nomatterhowhightheSWRgets.Thisfeaturecanproveinvaluableonbandsthathamsmustsharewithshortwavebroadcasting,suchastheupperendof40meters.WithFSK,theLOfrequencyissetafewhundredhertzaboveorbelowboththemarkfrequencyandthespacefrequency.It’sthesametypeofplugthatyoufindincell-phoneandtabletdevicechargers.Ihaveuploadedlotsofvideosinvolvinghamradioandhobbyelectronicstothatsite,alongwithvideossupplementingsomeofmytextbooks,afewopedblurbs,andevenalittlemountainfuddy-duddyhome-cookingadvice(ormischief)!Youmightalsolikemywebsiteatwww.sciencewriter.net.TheMULFdiffersfromtheshortwaveMUF.AmidsizecarcanserveasadecentRFgroundat2metersor6meters,buttheefficiencyofthatsamegroundsystemgrowsworseasthewavelengthincreasesuntil,at80metersor160meters,thatsamevehicleprovidesalmostnoRFground.FIGURE2-1Genericdiagramofthecircuitformyfirstshortwaveradioproject,accordingtomybestrecollection.Pulloversomewhere,preferablyintoaparkinglot,andmakeyouradjustmentsthere.Sfericswillbotheryoulessonthisbandthantheydoon80-and-75,60,or40meters.Sfericsalmostneverposeaproblem;ifyouhear“thunderstormstatic”on12meters,you’ddowelltogooutsideandseeifadarkcloudisabouttocomeoveryou.Haveyoueverheardabroadcaststationsuddenlycomeinfrom,say,KansasCityasyouranaroundLakeHarrietinMinneapoliswithaportableFMheadsetradio?Ifyou’reworkingaDXstationthatlotsofotherhamsarewaitingtocontact,orifyou’reinacontest,youwon’tgetpersonalandthewholecontactwilltakeafewseconds.Here’sa“Zapper”!Youcanbuyautomaticantennatunersthesedays,someofwhicharedesignedforusewithspecificradios.ThelowestionizedregioniscalledtheDlayer.Thedirectionalpropertiesofanybroadsidearraydependonthenumberofelements(whetherornottheelementshavegainthemselves),thespacingamongtheelements,andwhetherornotareflectingscreenisemployed.Ducting,apeculiartypeoftroposphericpropagation,occurslessoftenthanbendingorscatter,butoffersmoredramaticeffects.•Ifyou’renotalreadyanARRLmember,joinup!DidYouKnow?Thereflectedwavealwaystravelsfartherthanthedirectwave.FIGURE6-6Atransmatchinamobileinstallationforincreasingantennabandwidthandoperatingonbandsatfrequenciesfardifferentthanthatoftheantenna’sdesignband.IrecommendthatyoutesttwoorthreeRTTYprogramsonyourcomputertofindtheonethatagreesbestwithyourtemperament.Thesezonesare3kHzwide,aboutthesameasthebandwidthofanSSBsignal.Nevertheless,inlow-currentsystems,thistypeofrectifiercanworkokay.IfyouwanttogetintoSWLorAWL,youcanbuyaready-madereceiver,buyakitthatyoucanassembleintoareceiver,orbuildyourownradiofromscratch.Afteryouhavefoundthecorrectswitchpositionbytrialanderror,adjustthepotentiometeruntilyougetminimum“trash”inyourreceiver.Youcanalsofindvoltageregulatorsinintegrated-circuit(IC)form.IfaTNChasitsownmemory,itcanstoreanincomingmessageindefinitely,andsenditoutagainatanytime.Youcanstringthewireupbetweenmorethantwosupports,anditdoesn’thavetogoinastraightline.Rememberthatthebestgeneratorsemploypowerinverterstoproduceclean,regulated,sine-waveAC.Thefeedpointofaverticalantennagoesatthecenterofthecounterpoise.Youcanuseplainlanguagetodescribetechnicalthingswhenworkinginvoicemodes.TheElectricalSystemBeforeyoudecidewheretoputyournewhamradiostation,you’llwanttomakesurethatyoucangetenoughelectricitytotheequipment.Onthedownside,the10-meterbandspendsagreatdealoftimein“hibernation,”whenitbehavesmorelikeaVHFbandthananHFband.Doyounoticeapattern?TipRatherthansending“QRL?”toaskifafrequencyisinuse,experiencedoperatorssometimessendthelettersIE(di-dit,dit).•Neverusewirelessequipmenthavingoutdoorantennasduringthundershowers,orwhenlightningexistsanywhereinthevicinity.Agroupofhamshungouton40metersaround7.030MHzandhadcasualQRQCWconversationsatspeedsinexcessof50wpm.Mostpeoplearen’t;andinfact,theyhateit.Whenthathappens,youcanseetheaurora(northernandsouthernlights)onclearnightsathighlatitudes,andshortwaveradioreceptioncanfailcompletelywithinsecondsatallfrequencies.Iguesswecanonlywaitandsee,justaswedidwith,say,theY2K(year-2000)computerbug!Idon’tsensemuchinterestamonggovernmentofficialstospendanymoneytohardenourinfrastructureagainstthisthreat,howevergreatorsmallitultimatelyprovestobewhenthesunfinallydecidestohave“thefitofallfits.”LongwaveRadioCommunicationsspecialistscalltherangeofradiofrequenciesextendingfrom30kHzto300kHzthelow-frequency(LF)orlongwaveband.Tomakearequest,sendtheapplicableQsignalwithnothingafterward.Youmustoperateaquarter-wavelengthverticalantennaagainstalow-lossRFgroundifyouwantreasonableefficiency.•Channelscan—Insomeradiosforuseonanyhambandfrom160metersthroughmicrowaves,youcanscanthroughapreselectedsetofchannelsstoredinmemory.OnSSBitwillsoundlikeagreatunrulycrowdofpeopleshouting(which,infact,itis);onCW,itwillsoundlikeapackofwildanimalsfromsomealienplanet,howlingintonesofdiversepitch.Allthroughmychildhood,Imarveledatthepowerofthosestorms,someofwhichrivaledtropicalcyclonesinferocity.Butsmallerantennascangetyoucontacts;aninductivelyloadedvertical,mountedonthegroundwithagoodradialsystem,willprovidehoursoffun.ElectricalversusRFGroundElectricalgroundingconstitutesanimportantconsiderationifyouplantohavegoodreceptionandliveforalongtimetoenjoyit!Agoodelectrical(DCandutilityAC)groundcanhelpprotectyourequipmentfromdamageiflightningstrikesinthevicinity.Whenyoutuneinasignal,itcomesoutofyourspeakerorheadsetasarapidlyfluctuatingsequenceofaudiotones.Ifyouwant,youcanaddaccessoriesuntilyour“rig”takesupanentireroominthehouseorthebetterpartofacellar,asdoesmyinstallationshowninFig.Alternatively,youcanuseacomputer,equippedwithadedicatedprogramforencodinganddecodingSSTV,alongwithawebcamorthecomputer’sbuilt-incamera,ifithasone.Nolonger!SharingwithOtherServicesAmateurRadiooperatorsmustsharethisbandwithfixedservicesoutsidetheUnitedStates.IfyouwanttohavealongCWconversationandtheotherstationdoestoo,youcankeepatitallday,oraslongasthebandwillstayopenforyou.IhavetoremindmyselfofthisprecautioneverytimeIdownloadanythingbecausesometimesIwantto“cuttothechase”rightaway.Youwon’t,orshouldn’t,hearSSBatallon30meters.IuseabasicprogramcalledMMTTY,whichcameonaCD-ROMwithmydigitalmodeinterfaceunit,manufacturedbyWestMountainRadioaround2003.Whenthemotorfirststartsup,docurvessuddenlyappearonthedisplay,veeringtotherightandthenstraighteningoutasverticallines?Adirect-conversionreceiverprovidesrelativelypoorselectivity,meaningthatitcan’tdoagoodjobofseparatingsignalswhentheylieclosetogetherinfrequency.I’mluckyinCWcontestsandotherCWcompetitiveoperatingvenuesbecausemycallsigniseasytocopyonCW,andIhardlyeverhavetorepeatit.Anomnidirectionalgainantennaenhancesthereceivingandtransmittingrangeoftherepeater.Noviceshaveslicesof1.25meters(222.000MHzto225.000MHz)and23centimeters(1270.000MHzto1295.000MHz).Youmusttakewrittenteststogetthelicenses,butyoudon’thavetodemonstrateanyknowledgeof,orproficiencyin,theMorsecodeasyouhadtodoinyearsgoneby.IfyoucarefullychoosetheLOfrequency(orfrequencies)whenyoudesignasuperhet,imagesandbirdieswillrarelycauseproblemsduringordinaryoperation.However,innonCWtextmodes,bothstationsnearlyalwayscarryontheirQSOonpreciselythesamefrequency.Likeitscounterparton75meters,“40-meterphone”getsalotofuse.InAM,thebandwidthalwaysequalstwicethehighestaudiomodulatingfrequency,assumingthatthetransmitterisworkingproperly.You’llinstantlyrecognizeanSSTVsignalbyitssound,onceyou’veheardafewofthem!DidYouKnow?Sothewavesaren’ttrulycontinuous;they’reintermittent.You’llalsoneedanantennaofsomesort,preferablylocatedoutdoors.18.Noinexperiencedpersonshouldeverattempttoclimbanyantennasupportstructure.Actually,it’spartoftheMFspectrum,nottheHFspectrum,whichtechnicallystartsat3MHzandgoesupto30MHz.Nevertheless,mosthamsthinkof160metersasanHFband.TheMFSKmodeissidebandsensitive,soifyou’vegotyourradiosettoreceivesignalsintheLSBmodeandtheoperatorattheotherendissendingthesignalintheUSBmode,you’llhavetoreversethesenseorpolarityofyourreception.Lookforthelowestpossiblenumber.PresumablytheFCCwantedtomotivateasmanyhamsaspossibletogaintechnicalknowledgeandoperatingproficiency.Atthedestinationorreceivingstation,theanalogsignalsfromthetelephonelineorradiogetconvertedbackintodigitalpulseslikethoseproducedbytheopticalscanneratthesourceortransmittingstation.TheUPShasabatterythatchargesfromutilityelectricityundernormalconditions,butprovidesafewminutesofemergencyAC(withthehelpofsomesophisticatedelectroniccircuits)iftheutilitypowerfails.Thatstateofaffairscanprovedifficulttoattain,butlatter-dayengineershavefoundawayaroundthetrouble!ForNerdsOnlyTheefficiencyofageneratorequalstheratiooftheelectricalpoweroutputtothemechanicaldrivingpower,bothmeasuredinthesameunits,suchaswattsorkilowatts,multipliedby100togetapercentage.Thegainincreasesasthenumberofelementsincreases.WhatHappenedtoIt?Innegativemodulation,theinstantaneoussignallevelisinverselyproportionaltothebrightnessatanygivenpointontheimage.MostoftheotherHFbandswereallocatedaccordingtothesame“CW-centric”philosophy.Thetransmitterandreceiverineffectroamallovertheband,followingeachotherfrommomenttomomentaccordingtoa“secretmap”thatonlytheyknow.•Ignitionnoiseandpower-linenoiserarelyposeseriousproblemsforreceptionatVHFandUHF,althoughvehiclealternatorscansometimesproduceanannoyingwhineinthereceiverandasimilarwhineinyourtransmittedaudio.Mostoftheeffectivedielectricisairinsidethecylindricalsupportingstructure.Standingby!WhenIsaythesethingsatmyleisurelywesternpace,ittakesme25seconds.IonosphericFlayerpropagationhasnotbeenobserved.YoucanbuyaQROradioforheavyportableandscaleitbackforQRPifyouwant;inlightportabletheradiowilllikelynothaveQROcapabilityanyhow.Forexample,you’llneedtoselectthecorrectCOMportforyourcomputeraudiobeforeyoucangettheprogramtoworkatall,

andyou’llhavetoplayaroundwiththeaudiolevelsinordertooptimizeeverythingintransmitmodeandmakesurethatyouputoutadecentsignal.However,theycanbephased,justasYagisordipolescan,increasingthegain,f/bratio,andf/sratio.However,ifconditionsarenotsogood,thetransmittingstationhastorepeatsomesetsofcharacters.(Theysoundcoolonbigsurround-soundspeakers,though,ofthesortIhaveinmy“shack”!)16MetersThefrequencyrangeof17.480MHzto17.900MHzhostsinternationalshortwavebroadcastinginabandknownas16meters.Infact,unlessathunderstormloomsonyourdoorstep,youwon’thearmuch,ifany,atmospheric“static”on17meters.Atthelowradiofrequencies,theionizedupperatmosphereofourplanetpreventsthenoisefromreachingthesurface.Themostruggedlinearscanprovide1500wattscontinuous(100-percentdutycycle)RFoutput,themaximumlegallimitforamateurservice.Ifyouneedtoknowthevelocityfactorforagiventransmissionline,youshouldcheckthemanufacturer’sspecifications.ThemostcommonBPSKmodeworksat31.25baudandgoesbythefull-lengthtechnicalmonikerBPSK31.IftwohamsinvolvedinarepeaterQSOdon’tletthemachinedropoutperiodically,itmighttimeoutafterawhileanyway,bringingtheQSOtoanunplannedend.Thismachinecanrunmyhamstationunderfull-power-transmitconditions,aswellasallthreeofmycomputersandthemicrocomputercontrolledfurnace,allatonce.Themicrophone,obviously,hastobeusedoutsidethebackpack,butthat’seasytoarrange.Unlicensedoperationwasallowedifthepowerwas100milliwatts(0.1watt)orless.AabbreviationsforCW,240–244adjustablepassband,149allwavereceiver,2alternatorwhine,230AmateurRadio,overviewof,3–6AmateurRadioEmergencyService(ARES),256amateurteleprintingoverradio(AMTOR),91–93AmericanRadioRelayLeague(ARRL),3AmericanStandardCodeforInformationInterchange(ASCII),17,80amplifiedautomaticlevelcontrol(AALC),99amplitudemodulation(AM),18–20analog-to-digital(A/D)conversion,93–94antenna:broadside,211–212coaxial,202–203cornerreflector,217dipole,199–200dish,215–216effectiveradiatedpowerof,207efficiencyof,197–199end-fire,210–211forshortwavelistening,54forwardgainof,208–209front-to-backratioof,209front-to-sideratioof,209–210half-wave,199–201helical,216–217horn,215indoortransmitting,225Jpole,201longwire,211loop,60–62,203–205loopstick,204parasitic,212–214phased,210–212powergainof,207–208quad,214randomwire,60–61vertical,201–203Yagi,213–214zepp,200–201antennatuner(transmatch),54,144–145,154–156,184–185,221antipode,50anti-VOXsystem,98ARRLOperatingManual,227,256ASCII,17,80aspectratio,103atmosphericnoise,171–172audiofiltering,36audio-frequency-shiftkeying(AFSK),79audiopassbandfilter,149AuroraAustralis,13AuroraBorealis,13auroralpropagation,13–14automaticfrequencycontrol(AFC),86automaticgaincontrol(AGC),153automaticlevelcontrol(ALC),87,98automaticnoiselimiter(ANL),149automaticrepeatrequest(ARQ),88,92auto-tunefunction,148averageforwardcurrent,158Bbackfeed,169–170backwarderrorcorrection(BEC),92backupgenerators,165–170balancedmodulator,21ballmount,187balun,221bandpassfilter,36,156bandscanning,148bandspreadcontrolinreceiver,43basebandspectrummonitor,67basementashamstationlocation,142–143baud,79Baudotcode,79–80beat-frequencyoscillator(BFO),27binaryphase-shiftkeying(BPSK),83–84birdies,28bitspersecond(bps),76blankingpulse,104–105bridgerectifiercircuit,159–160broadbandamplifier,154broadsidearray,211–212bulletin-boardsystem(BBS),95–96Ccapacitivecoupling,207capacitor-inputfilter,161carbon-monoxidedetector,168–169carrier,unmodulated,19ceramicfilter,150Cassegraindishfeed,215–216channelscan,148characteristicimpedance,218,220–221choke-inputfilter,161circuitefficiency,19circularpolarization,10CitizensBand(CB),6–8clarifier,251closedrepeater,102,181coaxialantenna,202–203coaxialcable,218–219codepracticefromW1AW,76coherentcommunications,38combustiongenerators,165–170contesting,247–249Continentalcode,16continuousreceivecoverage,147continuouswaves(CW),3,75–79,240–246conventionaldishfeed,215–216convertersforVLF,63–64cornerreflectorantenna,217coronae,173cosmicnoise,170counterpoise,206–207currentsurgeinantenna,156DdataredundancyinMFSK,88deadbanddelusion,228deadspot,11deltatuning,149desensitization,150detector:forAM,32forCW,32forFM,33–34forFSK,32forPM,33–34forSSB,35–36deviationinFMandPM,23–24dielectric,218–219DigiPansoftware,66–67,84–86,157digipeater,94–95digitalfrequencydisplay,147digitalinterfaceequipment,156–157digital-to-analog(D/A)conversion,93–94dipoleantenna,199–200direct-conversionreceiver,27–28directivityplots,208directorinparasiticarray,213–214dirtyelectricity,65–72discriminator,34dishantenna,215–216distortion,inAM,18–19dotsanddashes,3double-conversionreceiver,28doublesideband(DSB),21dual-diversityreception,37–38dualVFOs,148duplexer,102DXCenturyClub,250DXing,250–253dynamicrangeofreceiver,26–27,151EElayer,12earth-ionospherewaveguide,58earth-moon-earthcommunications,15effectiveground,208effectiveradiatedpower(ERP),207efficiencyofantenna,197–199efficiencyofcircuit,19electricalground,205–206electricalsystemforfixedhamstation,139–142electromagneticfields,8–9electromagneticinterference(EMI),205electromagneticpulse(EMP),175–176electromagneticspectrum,8–9ellipticalpolarization,10emergencypreparedness,256end-firearray,210–211envelopecompression,99envelopedetection,32externalnoise,170–176extremelyhighfrequency(EHF),table,9FFlayer,12F1layer,12F2layer,12facsimile(FAX),106–107fast-scantelevision(FSTV),103–105FederalCommunicationsCommission(FCC),6feedlines,217–224fidelity,20FieldDaycontest,194firstfloorashamstationlocation,143–146fixed-stationhamradios,146–152flywheeltuning,147forwarderrorcorrection(FEC),88,91forwardgainofantenna,208–209four-wireline,220,222frame,intelevisionimage,103freebanders,7frequencydisplay,digital,147frequency-divisionmultiplexing,38frequencyhopping,39frequencymodulation(FM),22–24,100–103,238–240frequencymultiplier,24frequency-shiftkeying(FSK),17–18,79frequencysweeping,40frequencysynthesizers,23frequencyversuswavelength,44frontendofreceiver,26,31,150front-to-backratioofantenna,209front-to-sideratioofantenna,209–210fullbreak-inoperation,148fullquieting,231full-waverectifiercircuits,159–160fundamentalfrequency,68Ggalacticnoise,170gallium-arsenidefield-effecttransistor(GaAsFET),27generators,backup,165–170geodesicarc,50geomagneticstorm,57greatcircleroute,50greyline,51–52ground:electrical,205–206radio-frequency,145–146,206–207groundloops,206ground-mountedverticalantenna,202ground-planeantenna,202–203groundsystems,205–207Hhalf-waveantennas,199–201half-waverectifier,159HallicraftersSX-130receiver,43–44hamradiofrequencybands,44–54graphof,132proposednew,137shorterthan2meters,135–137tableof,532meters,134–1356meters,132–13310meters,130–13112meters,128–13015meters,126–12817meters,124–12620meters,123–12430meters,12240meters,119–12160meters,118–11975meters,115–11780meters,115–117160meters,113–114hamradiolicenseclasses:Advanced,112–113current,109–112discontinued,112–113Extra,111–112General,111Novice,112Technician,109–111TechnicianPlus,112hamradiolicenserenewal,112hams,definitionof,2HamScopesoftware,67,84–86,157handshaking,88harmonicsuppression,152harmonics,66,68–70,87,152heavyportableoperation,184–185helicalantenna,216–217heterodynedetection,32HFmobileoperation,advantagesof,181HFportableoperation,advantagesof,189–190high-frequency(HF)definitionof,1table,9horizontalpolarization,10hornantenna,215Iidleinsertion,89ignitionnoise,174–175,180imagerejection,151images,28,151impedancebridge,155impulsenoise,174indoortransmittingantenna,225inductiveloading,179intelligibility,19intermediatefrequency(IF),28,31–32intermodulationdistortion(IMD),30,86–87intermodulationspuriousresponseattenuation,151InternationalMorseCode,16ionosphere,11–13isolationswitch,169–170JJpoleantenna,188,201jammingsignal,53junctionfield-effecttransistor(JFET),30Kkey,telegraph,77keyboardkeyer,77–78keyer,electronic,77–78,149Lladderline,220–221librationfading,15–16licenseclasses,hamradio:Advanced,112–113current,109–112discontinued,112–113Extra,111–112General,111Novice,112Technician,109–111TechnicianPlus,112licenserenewal,hamradio,112lid,229–230lightportableoperation,184–185linearamplifier,139–140,152–154line-of-sightwaves,10–11localoscillator(LO),27long-pathsignal,50LongRangeNavigation(LORAN),113LongwaveClubofAmerica(LWCA),63longwavecoverage,147longwaveradio,2,57–64longwireantenna,211loopantenna,60–62,203–205loopstickantenna,204lossresistanceinantenna,179,198–199lowersideband(LSB),19–21,96–97lowestusablehighfrequency(LUHF),59lowfrequency(LF),table,9low-frequencyexperimentalradio(lowFER),61–63lowpassfilter,156Mmagneticmount,180maintuningcontrolinreceiver,43markfrequencyinFSK,32maximumusablefrequency(MUF),13,55–56maximumusablelowfrequency(MULF),59mechanicalfilter,150mediumfrequency(MF),table,9memory,programmable,148meteorscatterpropagation,14–15mixer,27mixingproducts,30MMTTYsoftware,81–82mobileantennaconsiderations,179mobilebandoptions,177–182mobileoperation,5–6,177–184mobilepoweroptions,182–184modem,17,76moonbouncepropagation,15Morsecode,3,16–17,75–79,240–246Morsecoderequirement,past,77multimeter,140MultiModesoftware,83multiple-frequency-shiftkeying(MFSK),88–90multiplexing,38–39Nnarrowbandfrequencymodulation(NBFM),23–24,101negativefeedback,98node,inpacketradio,94–95noise,external,170–176noiseblanker,148,173noise-cancelingantenna,70–72noisefigure,27,150–151noiselimiter,173noisequieting,151non-CWtextmodes,operationin,246–247notchfilter,149–150Oopendipoleantenna,199–200openrepeater,102openwire,219–221operationofahamstation:AMTOR,246–247contest,247–249CW,240–246DX,250–253FM,238–240MFSK,246–247PSK31,246–247QRP,254–255rag-chew,253–254RTTY,246–247SSB,232–238opticalscanner,106overmodulation,98Ppacketradio,93–96packetradiobulletinboardsystem(PBBS),95–96packets,88,93–96paddleforkeyer,77–78panoramicreception,149parallel-wireline,219–222parasiticarrays,212–214parasiticelement,212–213peakinversevoltage(PIV),158–159penumbraofsunspot,54–55phasecancellation,175phasemodulation(PM),22–24phaseopposition,11phasedarrays,210–212phase-shiftkeying(PSK),67,83–87phasingharness,210phasingsystem,210phoneticalphabet,232–233picketfencing,11pirates,7polarizationofEMwave,10portableantennaconsiderations,186–187portablebandoptions,184–190portableoperation,184–193portablepoweroptions,190–193portablewhipantenna,188poweradapterplug,184powergainofantenna,207–208power-linenoise,175,180powersupplies,158–165power-supplyfiltering,160–161powertransformers,158powertransistor,162preamplifier,30,147–148precipitationnoise,172–173precisionreadout,147preselector,31productdetector,35–36programmablememory,148propagationofradiowaves,10–16pulse-amplitudemodulation(PAM),24–25pulse-codemodulation(PCM),25–26pulse-durationmodulation(PDM),24–25pulse-intervalmodulation(PIM),25pulse-widthmodulation(PWM),24–25pushtotalk(PTT),97–98QQmultiplier,150QROmobileoperation,advantagesof,182–183QROportableoperation,advantagesof,191–192QRPmobileoperation,advantagesof,183–184,254–255QRPportableoperation,advantagesof,192–193,254–255quadantenna,214quarter-waveverticalantenna,201–203Rradialsinantennasystem,202–203,206–207radiationpatterns,208radiationresistance,154,179,197–199radio-frequency(RF)carrier,18radio-frequency(RF)ground,145–146,206–207radio-frequency(RF)spectrum,8–9radionoise,46RadioShackstores,73radioteletype,17–18,79–83radio-wavepropagation,10–16ragchewing,253–254randomwireantenna,60–61raster,103ratiodetector,34receiverincremental(oroffset)tuning(RIT),148,251rectangularresponse,148rectifierdiodes,158–159rectifiercircuits:full-wave,159–160half-wave,159repeater,101–103,180–181,238–239rectangularresponse,32reflectorinparasiticarray,213–214regenerativereceiver,42regulatorchip,162retracing,104reverse-biasvoltage,159ribbonline,220,222RigBlasterProinterface,81,157ringinginaudiofilter,36ripplesuppression,161RSTsystem,230–232SSaintElmo’sfire,173selectivesquelching,37selectivityofreceiver,26semibreak-inoperation,148sensitivityofreceiver,26–27sferics,46,171–172shapefactor,31,148,152short-pathsignal,50shortwaveband,definitionof,1,41shortwavebroadcastbands,44–54graphof,53tableof,4511meters,5213meters,5115meters,5116meters,5019meters,5022meters,4925meters,4931meters,48–4941meters,4849meters,47–4860meters,46–4775meters,4690meters,46120meters,45–46shortwavelistening(SWL),41–57shortwaveradio,definitionof,1shortwavereceiver,2signal-plus-noise-to-noiseratio,26signalreporting,230–232signal-to-noiseratio,26simplex,101simplexteleprintingoverradio(SITOR),91SINAD(signaltonoiseanddistortion),151single-conversionreceiver,28–29singlesideband(SSB),7,20–22,96–100,232–238skipzone,47skywaves,11–13slopedetection,33slow-scantelevision(SSTV),105–106smallbackupgenerators,165–170smallloopantenna,60–62solarflares,56–57solarflux,55,171solarnoise,171spacefrequencyinFSK,32spectraldisplay,19,85–86speechclipping,100speechcompression,98–99splatter,86–87,99–100split-bandduplex,247split-frequencymode,252squelchsensitivity,151squelchthreshold,36–37squelching,36–37solarflares,14solarnoise,15sporadic-Epropagation,12spreadspectrum,39–40standing-waveratio(SWR),153,185,223–224standingwaves,223–224step-downtransformer,158step-uptransformer,158sunspotcycle,55–56sunspots,54–57superheterodynereceiver,28–29superhighfrequency(SHF),table,9surfacewaves,11surgeprotector,140SWRmeter,185,189synchronizedcommunications,38Ttelegraphkey,77teleprinter,79–80television:fast-scan,103–105slow-scan,105–106terminalnodecontroller(TNC),93time-divisionmultiplexing,38time-shiftingcommunications,93tonesquelching,102transceiverforhamradio,3–5transformer,power,158transientsuppressor,140,163–164transmatch,54,144–145,154–156,184–185,221transmissionlines,217–224transmit/receive(T/R)switch,88transmitteroffset,251troposphericbending,13troposphericducting,13troposphericpropagation,13–14troposphericscatter(troposcatter),13tubularline,220–221twinlead,222UUHFmobileoperation,advantagesof,180UHFportableoperation,advantagesof,187–189ultrahighfrequency(UHF),definitionof,2umbraofsunspot,54–55uninterruptiblepowersupply(UPS),163unmodulatedcarrier,19upperfloorsashamstationlocation,146uppersideband(USB),19–21,96–97Vvelocityfactor,199verticalantenna,201–203verticalpolarization,10veryhighfrequency(VHF):definitionof,2table,9verylowfrequency(VLF),table,9voice-modeexpressionsinhamradio,235–237voltagedoubler,160VHFmobileoperation,advantagesof,180VHFportableoperation,advantagesof,187–189VibroKeyerDeluxe,78VLFconverters,63–64voice-operatedtransmission(VOX),97–98voltageregulation,162volt-ohm-milliammeter(VOM),140Wwaterfalldisplay,67,85–86waveguide,223waveguidepropagation,58wavelengthversusfrequency,44weightcontrolforCW,150widebandfrequencymodulation(WBFM),24,101wordsperminute(wpm),16,75–76workingDX,250–253W1AWcodepractice,76XYZYagiantenna,213–214Zenerdiode,162zeppantenna,200–201zerobeat,27,247Whilesmalltransmittingloopsexist,youwon’tencounterthemoftenbecausethey’rehardtodesignandexpensivetobuild.HowDoesIt“Know”?AspeechcompressioncircuitoperatesinmuchthesamewayasanALCcircuitdoes.3HamRadioCommunicationsModesMorseCodeRadioteletypePhase-ShiftKeyingMultiple-Frequency-ShiftKeyingAmateurTeleprintingoverRadioPacketRadioSingleSidebandFrequencyModulationImagesandVideo4HamRadioLicensesandFrequenciesToday’sLicenseClassesDiscontinuedLicenseClasses160Meters80Meters60Meters40Meters30Meters20Meters17Meters15Meters12Meters10Meters6Meters2MetersBeyond2Meters5FixedHamStationsWhereWillYouPutYourRig?Warning!AdvantagesofQRPPortableIfyou’dratherstickwithQRPwhenoperatingmobile,morepowertoyou(punintended)!Butyoushouldexpectchallenges,justasyouwouldendurewithQRPmobileoperation.Youcanobtainthetonefrequencyforarepeaterbyjoiningtheclubthatoperatesit,orbylookingitupinadatabase,suchasthelatesteditionofTheARRLRepeaterDirectory.FIGURE2-9GenericdiagramofaVLFconverter.•Inmanycases,aportableQTHcanturnouttobefarbetterthanyourownhomeQTH,asminewasattheStargazer.Althoughthisillustrationcanserveasacrude“drawing-board”engineeringblueprint,theoptimumdimensionsofathree-elementYagiinpracticewillvaryslightlyfromthefiguresshownhere,becauseofimperfectionsinreal-worldhardware,andalsobecauseofconductingobjectsorterrainirregularitiesnearthesystem.WaveguideAwaveguideisanRFtransmissionlineusedatUHFandmicrowavefrequencies.•Notinthiscase!Allofthedevices,takentogether,consumelessthan10amps(2/3ofthebreakerrating),eveniftheyallrunatonce.Coppercankillplants.)Youcanbringthenearendofthewireinthroughawindowsashandconnectittothebackofyourradio(afterstrippingofftheinsulationforaninchorso),whereyoushouldfindaterminalspecificallymeantforexternalantennas.However,IdidlocateaprogramcalledMultiModeafteranInternetsearch,andtheauthorsclaimthatitallowsaMacintoshcomputertosend,aswellasreceive,RTTYandseveralotherdigitalmodeswithoutaseparateinterfaceunit.ThenoisefigureisimportantatVHF,UHF,andmicrowavefrequencies,whererelativelylittlenoiseoccursintheexternalenvironment,andtheinternalnoise,therefore,limitsthesensitivity.Thatway,youminimizetheriskofignitionnoiseandalternatorwhinecomingintoyourradiothroughtheDCpowercable.Theoriginal11-meterbandhad23channels,andonlyamplitudemodulation(AM)wasused.Gotowww.hamradiolicenseexam.com/which-exam.htmAswithothergovernment-relatedmatters,abunchofrulesandregulationsgoalongwithallthisinformation.Thesecondarywindingsofatransformerintendedforthatapplicationmustconsistofheavy-gaugewire,andthecoresmusthaveenoughbulktocontainthelargeamountsofmagneticfluxthatthecoilsgenerate.ThismodelistheVibroplexVibroKeyerDeluxe.Youmightwanttosay“73,”whichmeans“Bestregards!,”andsomeotherformoffarewellpeculiartohams,suchas“Seeyoulaterondownthelog.”Iftheotheroperatorisoftheoppositegender,youmightalsothrowin“88,”whichmeans“Loveandkisses”inaplayfulsortofway.Coronaeproduceastronghissorroarinradioreceivers.TipFour-wirelinehasinherentlybetterbalancethantwo-wirelinedoesinpracticalsystems,andit’slesslikelytoradiatesignalsorpickupunwantednoise.Asageneralrule,mostdaytimeDXhappensat20metersandshorterwavelengths,whilemostnighttimeDXhappensat30metersandlongerwavelengths.Thesignalsareeasytofindonthebands,youcanalmostalwaysfindafewifabandisopen,andmanyofthepeoplewhousethatmodearebeginners,poortypists,orElmerslookingtohelpnewcomersalong.AllocationsbyLicenseClassExtraClassoperatorscanusethewhole20-meterband,subjecttomodeconstraints.Also,itshouldnotbepossibleforpowerlinestofallorblowdownonanantenna,evenintheeventofaviolentstorm.Inthiscase,theuppersideband(USB)energyalongwiththecarrierwavehasbeeneliminated,leavingonlythelowersideband(LSB)energy.Aplasticcup,wedgedunderneaththeCBradio,keepsbothunitsfromwobbling.Thefidelityimprovesasthebandwidthincreases(justasitdoesinanyothermode),butinhamradiopractice,intelligibilitysurpassesfidelityinimportance.Aground-planeantennaworksbestwhenfedwithcoaxialcable.Thetransferthentakesplaceautomatically,inmuchthesamewayasdatagoesoveronlinecomputernetworks,exceptthatsomeofthelinkgoesoverhamradiomedia,whichbylawcan’tbecommercialized.Neverviewthesundirectlythroughdarkfilmnegatives,thinkingthattheunexposedfilmwillprotectyoureyes.Long-timeusersoftheHFradiospectrumknowallaboutthiseffect.Doyouwanttotestanewantennaonthebandforwhichit’sdesigned(ormaybeonabandforwhichit’snotdesigned,outofsheercuriosity)?Themarkandspacefrequenciesdifferby170Hz,resultingintheso-called170Hzshift.It’sexpensive,butmosthardlinescanhandlemorepower,andhavelowerlossperunitlength,thanordinarycoaxialcable.Butit’stheoneIrecommendifyoucanmanageit.Thegenerator’sinternalcombustionenginecanrangeinsizefromafewhorsepower,comparabletotheoneinalawnmowerorsnowblower,tohundredsofhorsepower,comparabletotheenginesintrucks,tractors,andconstructionequipment.Radiohamsexpresscodespeedinwordsperminute(wpm),whereone“word”averagesfivecharactersinlengthwithathree-bitpausebetweencharacters.Usually,yourfrequencyappearsatthecenterofthehorizontalscale.7-1B.Theoutputofthefrontendmixes(heterodynes)withthesignalfromatunable,unmodulatedLO.PortableAntennaConsiderationsIfyouplantodoheavyportableoperation,you’llneedanantennathatyoucaneasilytransportandquicklysetupatthedestinationorstopoverQTH.Theoretically,auroralpropagationcanoccurbetweenanytwopointsontheearth’ssurfacefromwhichthesamepartofanactiveauroraregionliesonalineofsight.Youmightwanttodeploytheantennainsuchaswaythatyoucantakeitdowninahurryshouldtheneedarise.20MetersThe20-meterbandgoesfrom14.000MHzto14.350MHz.Hamsdon’thavetosharethisbandwithanyotherservices.Whenshoppingforaradio,lookforthelowestpossiblemicrovoltfigureassociatedwith20dBofnoisequieting(NQ).ThecircuitshowninFig.Aswith120meters,conditionstendtopeakinthewinter(forthesamereasons).Onsomebandsandforsomelicenseclasses,furtherrestrictionsapply.Atmosphericnoiseintheformofsferics(“static”)presentsaproblemon160metersduringthemonthswhenthundershowerscommonlyoccur.FrontEndAtlowandmediumfrequencies,considerableatmosphericnoiseexists,andthedesignofafront-endcircuitissimplebecauseyoudon’thavetoworryverymuchaboutinternallygeneratednoise.Someofthebetterelectronicsorhobbystorescarrythesereceivers,alongwithantennaequipment,foracompleteinstallation.FactorMyth?WhenusingASCIIwithFSKorAFSKforRTTY,youcanworkatspeedshigherthan45.45baud(60wpm).Athigheraltitudes,youfindtheF1layerandtheF2layer.HerearesomeoftheadvantagesofgoingQRPforportableoperation.Iffedwithalow-lossfeedlineusingatransmatchatthetransmitterend,andifplacedatleastaquarterwavelengthabovetheearth’ssurface,suchanantennacanofferexceptionalperformancefortransmittingandreceiving.AnOldTimerRemembersWhenIfirstgotmyGeneralClasslicenseinMarchof1967,the40-meterphonebandwentonlyfrom7.200MHzto7.300MHz.Thelower2/3ofthebandservedashometoCWandRTTYoperatorsonly.Socannearbythundershowers.TheJpoledoesnotrequireanyelectricalgroundsystem,afeaturethatmakesitconvenientinlocationswithlimitedrealestate.TechTidbitWhenfewornosunspotsexist,theMUFcandropdowntoabout4or5MHzbecausetheionizationoftheupperatmosphereisleastdensewhensunspotactivityreachesitsminimum.Thefluctuatingcapacitancecausesvariationsoftheresonantfrequencyoftheinductance-capacitance(LC)tunedcircuit,causingsmallvariationsinthefrequencygeneratedbytheoscillator.Atmosphericnoisediminishesasyougetabove30MHzorso.AllocationsbyModeOn1.25meters,therangefrom219.000MHzto220.000MHzisreservedforfixeddigitalmessageforwardingsystems.Somehamssimplychataboutanythingthatcomestomind(exceptbusinessmatters,whichremainillegaltodiscussusingthehamradiofrequenciesintheUnitedStates).Ifyouwanttogetstartedwiththishobby,youcancontactyourlocalAmateurRadioclubortheAmericanRadioRelayLeague(ARRL)inNewington,Connecticut.Theatomsintheairgainorloseelectrons,sothattheybecomeelectricallycharged.Othersprefertodownloadcomputerprogramsandlettheircyberhardwaretakecareofitall!CHAPTER4HamRadioLicensesandFrequenciesAmateurRadiooperatorsenjoyoperatingprivilegesinnumerousslicesoftheradiospectrum.Rememberthatasthefrequencygoesup,thefree-spacewavelengthgetsshorter.Nevertheless,youshouldneverassumethat10metersisdeadjustbecauseyoudon’thearanysignalsthere.Inotherwords,thetwosignalsareusuallyzerobeatwitheachother.Thefirstflooristhemostcommonplaceforsmall“dens,”whichservewellashamradiozones.Solistenwithabandon,andtransmitwithcare.Supposethatyougraduallyraisethefrequency.TipNomatterhowlowtheamountofelectrical“juice”thatyourrigdemandsfromtheutility,youshouldtrytoavoidpoweringyourequipmentthroughanextensioncord.Asafinalprecautiontokeepthegeneratoroperatingatitsbest,youshouldconnectthegenerator’sgroundterminaltoaknownelectricalgroundthatyouhavetestedforcontinuitywiththemaingroundforyourwholehouse.SomeCBoperators,incontrast,enjoytherecreationalaspectofradiocommunication.Second,theloadresistancemustequaltheZooftheline.IfyouknowwhatImean,ifradioholdssomemagicforyoutoo,thenyou’llgetthemostoutofthisbook.Ifyouwanttodiscusspoliticswithacitizenofanothercountry,forexample,you’reenteringperilousterritory.Comparethatratewiththecomputermodem(modulator/demodulator)speedsthatwemeasurethesedaysinmillionsofbitspersecond,orinsomecases,billionsofbitspersecond!Asslowasitpokesalongcomparedwithcomputerdatatransmissions,somehamradiooperators,myselfincluded,enjoyCWasanartform;it’sjustplainfuntosendandreceive.Oneofthemostinterestingandpromisingnewdigitalmodesismultiple-frequency-shiftkeying(MFSK).Noneofthehamradiodigitalprogramstakeupmuchcomputerprocessingpowerormemory,sotheyrunfastevenonsimplemachines.Ineffect,theionosphereactsasa“radiowavemirror”atthesewavelengths.Cellphonesdidn’texistthen,somycommunicationthrougharepeatersavedthatfamilyalotoftediumandgrief.FoldedDipoleAfoldeddipoleantennaconsistsofahalf-wavelength,center-fedantennaconstructedoftwoparallelwireswiththeirendsconnectedtogether,asshowninFig.You’llhavetorunasignificantlengthofwirefromyourrigtothegroundrod,andthatwirewillactaspartofyourantenna!Theproblemmightnotcausetoomuchtroubleatthelowestfrequencies(1.8MHzand3.5MHz),butitwillaffectperformanceathigherfrequencies.73(BestRegards),StanGibilisco,W1GVCHAPTER1HobbyRadio:ATechnicalOverviewHobbyradioencompassesthreeactivitiesthatanyonewithalittlesparecashandmotivationcanenjoy:shortwavelistening(orSWL),AmateurRadio(alsocalledhamradio),andCitizensBandradio(usuallycalledCBradio).Thelossoccursbecauseoftheohmicresistanceoftheconductors,becauseofskineffect(atendencyforRFcurrenttoflowmostlynearthesurfaceofaconductor),andbecauseoflossesinthedielectric.•Rectangularresponse—AgoodIFbandpassfilterexhibitsaso-calledrectangularresponse.PeripheralEquipmentManyhamradiooperatorsgetbywithatransceiver,aheadset,andamicrophonefortheirhomestationuse.Thiscutoffpointiscalledthemaximumusablefrequency,orMUF,forthetwolocationsinquestion.TheEMEpathlossincreaseswithincreasingfrequency,butthiseffectisoffsetbythemoremanageablesizeofhigh-gainantennasasthewavelengthdecreases.Radioastronomersanalyzecosmicnoiseinanefforttoimprovetheirunderstandingoftheuniverse.TheFlayerlackstheionizationdensitynecessarytobendthesignalsbacktothesurfaceatasharpenoughangletoallowreceptionbyY,buttheshallowerangleforZworksoutjustfine.ButspeechcompressioncarriestheprocessfartherthanordinaryALC.Ideally,thesplitshouldbelargeenoughsothatthereceiverpassbandsoftheDXandcallingstationsdon’toverlapevenslightly.TABLE1-1FrequencybandsintheRFspectrum.Here’saTrick!NearlyallPSK31programsandinterfaceunitsgenerateaudiotonesintherangeofapproximately300Hzto3000Hz,andsendthemtothemicrophoneinputofatransceiverinSSBmode.Inthatsense,acollectionofhamradiopacketstationsanddigipeaterscanserveasan“alternativeInternet.”ThatcapabilitymightprovehandysomedayiftheregularInternetsuffersamassiveoutage,eitherasaresultofnaturaleventsorasaresultofhumansabotage!Hamradiowillthengetachancetoshowitsvalueforpublicservice,asithasdoneduringandaftermanypastdisasters.Themostcommoneffectsarescatteringandbending.InitiatingaContactOnanyrepeater,youwon’thearanybodysendCQunlessthey’veneverusedarepeaterbefore(orthey’reanon-hamwhohasgottenholdofahamradioset).•GetintouchwiththeofficersofyourlocalAmateurRadioclubandaskabouttheiremergencypreparednessprograms.McGraw-HillEducationanditslicensorsdonotwarrantorguaranteethatthefunctionscontainedintheworkwillmeetyourrequirementsorthatitsoperationwillbeuninterruptedorerrorfree.Longdistanceionosphericpropagationoccursonlyoverpathsthatlieentirelyormostlyonthedarksideoftheplanet.Inordertoupgradeyourlicenseclass,you’llhavetotakeanothertest.Forexample,my1960sHallicraftersradiowouldonlygodowntothebottomoftheAMbroadcastband.Supposethatyoucouldgetridofthecarrierandoneofthesidebands,butstillconveyalltheinformationyouwant.5-2.MorseCodeandRadioteletypeTheMorsecodeisabinary(two-state)schemeforsendingandreceivingmessagesbyelectronicmeans,andit’salsotheoldest!Engineerscallitabinarycodebecauseithasonlytwopossibleconditions,either“allthewayoff”or“allthewayon.”Historically,English-speakingradioandtelegraphoperatorshaveusedtwodifferentMorsecodes.The15metershortwavebroadcastbanddoesn’tgetmuchuse.Withaloadofafewhundredwatts,thatamountoffuelprovidesseveralhoursofcontinuous,reliableACelectricity.Notonlycanyouhearthisstuff,butalso,withtheappropriateequipment,youcanseeittoo!Here’showyoucanputtogetheradevicethatwilldetectdirtyelectricityandproduceagraphicdisplayofitscharacteristics(althoughitwon’thelpyougetridofit).Eitherway,thepeakpulseamplituderemainsconstant;they’reallequallystrong.AlthoughIhavenotwitnesseditpersonally,I’vereadthatsignalswillsometimesshowupon-screeneventhoughahumanoperatorlisteningtothereceiveraudiocan’ttellthatanysignalexists.TheRigBlasterProallowsyoutoeasilytransmit,aswellasreceive,signalsinPSKandnumerousotherdigitalmodeswiththeappropriatesoftware.Ifyoufindarepeaterandnobodyisusingit,andifyouhaveyourradiotunedtoaccessit,youcansendyourcallandthensay“listening.”That’stheequivalentofCQonarepeater.Youexpressf/sratiosindecibels(dB),justasyoudowithf/bratios.AlthoughtheFCCnolongerissuesnewlicensesfortheseclasses,originalonesremainvalid.•Chapter3definesandexplainsthecommunicationsmethodsthathamradiooperatorsuse.StandingwavesarevoltageandcurrentvariationsthatexistonanRFtransmissionlinewhentheloadimpedancediffersfromtheZooftheline.•GetacopyofTheARRLOperatingManualandreadthechapterondisaster,publicservice,andemergencycommunications.Bothstationsidentifythemselvesperiodically,soifyouhaveanydoubtaboutwhichofthemyou’rehearing,listenforawhile.SomereceiversuseasecondmixerandsecondLO,convertingthefirstIFtoalower-frequencysecondIF.ForNerdsOnlyInaschemecalledphasecancellation,noisefromaspecialauxiliaryantennanullsoutthenoisefromthemainreceivingantenna,ineffectmakingthenoisekillitself.•Novices,Technicians,andTechPlusoperatorscanusethefrequenciesfrom7.025MHzto7.125MHzforCWoperationonly,withamaximumof200wattsoutput.Awell-defined,strongblankingpulsetellsthereceiverwhentoretrace,anditalsoshutsoffthebeamwhilethereceiverdisplayretracesbyeffectivelyturningthescreenasblackasitcangetduringthatbriefperiodoftime.SkyWavesTheupperatmosphere,wheninfluencedbyultravioletradiationandXraysfromthesun,canreturnradiowavestotheearthatcertainfrequencies.Warning!AdvantagesofQRPMobileIfyou’dratherstickwithQRPwhenoperatingmobile,youshouldexpectchallenges,especiallyifyouoperateonthelowerHFbands.Four-wirelineisnotusedasoftenasothertypesofparallel-wireline,althoughithassignificantassets.Ifyouputthefeedpointabovethegroundatleast4meters,thewholestructurewillmeasureonly8metersfromthemountingsurfacetothetipoftheradiator!TipBytrialanderror,trimtheradiatingelementandtheradialsofyourground-planeantennatogetoptimumperformancethroughoutthisband.Alsolike80metersand160meters,thepartofthespectrumaround5MHzsuffersadverseeffectsonaccountofsfericsduringthethunderstormseason.WhySoManyModes?TheAdvancedClasslicenseoriginatedmanyyearsago,andthentheFCCphaseditoutforacoupleofdecades.Youcancutradialsthatdoubleasguywirestothesamelengthastheradiatingelement.Duringtheearlytwentiethcentury,communicationsengineersperfectedawaytomodifyAMsignalsinpreciselythisway.Thecurrentcanheattheconductorstothepointthatthepolyethylenedielectricmaterialmelts;thevoltagecancausearcingthatmeltsorburnsthedielectric.Thenextsmallercirclerepresentsafieldstrength5dBdown(aradiation/responselevelof−5dB)withrespecttothemainlobe.Inordertoadjustthefrequencyoftheantenna,IusedanSWR-and-powermeterthatIboughtataRadioShackretailoutlet.Astronomersandcommunicationsengineersmonitorthesolarfluxatawavelengthof10.7centimeters,correspondingtoafrequencyof2800MHz.Atthisfrequency,thetroposphereandionospherehaveminimaleffectonradiowaves,makingobservationofextraterrestrialRFphenomenaeasy.Youcantellifthevoltagefluctuatesunderloadbyconnectinganold-fashionedincandescentlamptothesamecircuitasyourrig.3-12A).Forreceiving,thingsarealotsimpler.TheaudiooutputfrequencyequalsthedifferencebetweentheLOfrequencyandtheincomingcarrierfrequency.TheconstellationSagittariusliesinthedirectionofthecenteroftheMilkyWaygalaxy,andEMEperformancesufferswhenthemoonpassesinfrontofthatpartofthestellarbackgroundbecauseallthosestars,likeoursun,aregiganticradionoisetransmitters!Themoonkeepsthesamefacemoreorlesstowardtheearthatalltimes,butsomeback-and-forth“wobbling”occurs.Sometypesofpower-linenoisecanbeattenuatedbymeansofanoiseblanker.•AntennasforportableHFoperationcanworkjustaswellasthoseatyourhomestation.•AntennasforVHFandUHFhavemanageablesize.(Thespeedoflightinfreespaceis299,792kilometerspersecond.)15MetersShortwavebroadcastersrefertotherangeoffrequenciesfrom18.900MHzto19.020MHzasthe15-meterband,eventhoughhamradiooperatorscalltheirbandat21.000MHzto21.450MHzbythesamewavelengthname.Iftheydo,accepttheoffer!Iftheydon’t,askaboutthem.Meteorscatterandauroralcommunicationscanbecarriedout,butthey’realittlemoredifficulttoinitiateandmaintainthantheyareon6meters.However,theycanuseanylegallyauthorizedAmateurRadiomodeinthoseslots.Betweenthoselimits,intheso-calledbandstoprange,signalsareblocked.IfyouwanttorunhighpoweranduseanoutboardRFpoweramplifier(calledalinearamplifier,orsimplyalinear),you’llwanttohavea234-voltcircuitforyourrig,ratherthana117-voltcircuit.Atverylow,low,andmediumfrequencies,directwavescandiffract(goaroundcornersinobstructingobjects).Transmatchesareespeciallyhandyforportablestationoperation.HarmonicsApureACsinewaveappearsasasinglepiporverticallineonthedisplayofaspectrummonitor(Fig.Oftenthebandgetsdownrightcrowded!Alwaysremembertostaywithinthesubbandsallowedforyourlicenselevel.Unlesspeopleknowthattheantennaexists,theymightneverevennoticeit,especiallyifyoucangetitupintotrees.TipAtfrequenciesaboveabout10MHz(correspondingtowavelengthsshorterthanroughly30meters),theearthbecomesapoorconductor,andsurface-wavepropagationrarelyoccursfordistancesgreaterthanafewkilometers.TheycalleditSaintElmo’sfire,and,notknowingaboutelectricity,someofthemattributedittosupernaturalforces.WhenIfinallycarriedofftheexperiment,whichrequiredonlythepurchaseofanextramicrophoneplug,myrewardcameinstantly.Remembertostaywithinthesubbandsallowedforyourlicenseclass.Theaudiosystemconsistsofaninputdevicesuchasamicrophone,anoscillator,afrequencymodulator,andafeedsystemthatcouplestheRFoutputintothevideoamplifierchain.AsfarasIknow,engineersandscientistshaven’tformallydemarcatedtheexactlowerlimitoftheVLFrange;itvariesdependingonwhomyouconsult.WhenIfirstbecameahamin1966,IgotwhattheycalledtheNoviceClasslicense,whichrequiredmetosendandcopyasolidminuteofcharacters,errorfree,at5wpm.Mostlatter-dayelectronicdevicesneedonlyafewvoltstofunction.AnAMreceiverhasafilterwithapassbandofafewkilohertzandaselectivitycurve,suchastheoneshowninFig.Youcangetawaywithamodest-sizeantennaon30meters.TheMorsecode,whentransmittedusingsimpleon/offkeying,breaksdownintoanindefinitesequenceofdigitalintervalsorbits(binarydigits),wherethesignalexistsduringthewholelengthofthebit,orelsefornoneofitatall.Thisnoiseiscalledsferics.Youhaveanassetheresimilartotheoneyoucanenjoyon60meters.Thedisplaymightlookalittlestrangetoyouatfirst,especiallywhenyoutypecallsigns,butsendingeverythinginlowercasewilloptimizeyourtransmittingspeed(andmakeyoulooktootherslikeanexperiencedPSK31operator).Youdon’thavetoknowthecodetogetahamradiolicensenow,althoughatonetimenotonlydidyouhavetoknowthecharactersbutalsoyouhadtodemonstrateproficiencyatspecificspeeds,bothsendingandreceiving,dependingontheclassoflicensethatyousought.•Youcanuseabatteryotherthanthevehiclebatterytopowerthetransceiver.ForwardGainForwardgainisexpressedintermsoftheERPinthemainlobe(favoreddirection)ofaunidirectional(one-directional)antennacomparedwiththeERPfromareferenceantenna,usuallyahalf-wavedipole,initsfavoreddirections.Nolawstandsintheirway.Ahalf-wavelengthopenorfoldeddipoleinfreespaceprovidesausefulreferenceantennaforthepurposeofcomparisonwithotherantennas.Thebestwaytomakethathappenistokeepthegeneratoroutdoorswhenrunningit.•Themixerstage,inconjunctionwiththetunableLO,convertsthevariablesignalfrequencytoaconstantIF.Listen,Listen,Listen!Hasanyoneevertoldyoutohavebigearsandasmallmouth,orsomethinglikethat?AmateurRadiooperatorscanprovidecommunicationswhenallothertechnologiesfail.Ifconditionsgetprohibitive,thenineffectthespeedgoesdowntozerobecauseacknowledgmentsnevergetreceived.Getthecomputer,theinterface,andthesoftware,andwatchpeoplesendCQs,answerthem,andworkmultiplecontacts,andwhateverelsetheydo.BasicSSBTransmitterFigure1-12isablockdiagramofasimpleSSBtransmitter.IttakesadvantageoftheentireACcycle,soitconstitutesafull-wavevoltagedoubler.Underpoorconditions,thisprocessmakesfortediouscontact,butwithfewererrorsthaninmodes,suchasconventionalRTTY,thatdon’tuseARQ.Forexample,tryentering“HallicraftersSX-130”inthephraseboxofanInternetsearchengine.WhenadjustingyourequipmenttosendBPSK31,oranyotherdigitalmode,usingaudiotonesintothemicrophoneinputofaradio,youruntheriskofintermodulationdistortion(IMDor“intermod”)thatwillproducesplatter,orsignalartifactsthatcomeoutnear,butoneithersideof,youroperatingfrequency.Failingallthat,youcanputitinacornerofthelivingroom.Alinearwillnot,whenoperatedproperly,introducesignificantdistortionintothesignal,nomatterwhattypeofemissionthedrivingsignalhas.Ipluggedaquartzcrystalandamicrophoneintothat“boatanchor,”connectedmy40meterdipoletoit(notknowingmuchaboutantennasyet),andchattedwithotherhamsaroundtownasIsatinthefamilyfalloutshelterthatservedasmy“hamshack.”Beyond2MetersAtfrequenciesabove148MHz,radiohamsenjoyprivilegesonnumeroussmallslicesofthespectrum,asshowninTable4-1.Today,ifyoucanheararepeater,youprobablywon’tbeabletouseitunlessyouknowthesubaudibletonefrequencyforaccess.TheoldclasseswentbythemonikersNovice,TechnicianPlus,andAdvanced.Manyhamsusetransmittersthatputoutonly100or150watts,sotheyoptforanend-fed,randomwireastheantenna.7-3B.Thesepulsesgotoaprintingdeviceorcomputer.Amixerproducesoutputsignalsatthesumanddifferencefrequenciesoftheinputsignals.Ifyouaren’taradiohambuthaveoccasionto“employ”ahamradiooperatortogetamessagetoalovedoneinadisasterareasomeday,theradiohamwon’t(andlegallycan’t)acceptanyremunerationfortheservice.Linearscanfunctionwithamplitude,frequency,phase,orpulsemodulation.Intermediateaudiofrequenciesproduceshadesofgray.Notonlycanthetuninggetquitecriticalinregardstosettingthefrequency,butalsoyoucan’talwayseasilyseethesignalinagraphicaltuningaiddisplay,soyouendupguessingatwherethedashedlines(orothertuningboundarymarkers)shouldgo.Ifyougetinterestedinhamradioanddecidetogoforalicensesothatyoucancreatesignalsaswellasmerelylistentothem,trustme:You’llbegladyoudid.FIGURE3-11Here’swhatsplatterlookslikeonaspectraldisplayofanLSBvoicesignal.2-10A.•Strengthnumbersgofrom1to9.TheadvantagesofHFportableoperationresemblethoseofHFmobile.Radiohamsaremorelikelytoowntwoormorepersonalcomputersthanarenon-hams.You’llhearmostlylowersideband(LSB)on160,80,60,and40meters,whileuppersideband(USB)prevailson20,17,15,12,and10meters.TheRFamplifiersthatfollowanytypeofamplitudemodulator,includingabalancedmodulator,mustalloperateinalinearmannertopreventdistortionandunnecessaryspreadingofthesignalbandwidth,aconditionthatsomeengineersandradiooperatorscallsplatter.ThistypeofantennaworksasanefficientradiatoreveninthepresenceofconsiderablelossresistanceRLintheconductors,thesurroundingearth,andnearbyobjectsbecausetheradiationresistanceRRishigh.HamScope1.56wasauthoredbyanotherhamradiooperator.Figure1-18Cillustratesaratiodetectorcircuit.•Nevermanipulateorinstallanantennainsuchawaythatitcanfallorblowdownonutilitypowerlines.Whenaweaksignalcomesin,thenoiseleveldecreases.OntheHFbands,hamsusefrequency-shiftkeying(FSK)toaccomplishthis.Shortwaveradiostillplaysaroleininternationalbroadcasting,particularlyinthedevelopingcountries.ItcoveredfrequenciesfromthebottomofthestandardAMbroadcastbandat535kHzuptothetopofthatbandat1.605MHz,hadalittlegapwhereitdidn’treceiveanything,andthenallowedreceptionoveracontinuousrangeoffrequenciesfrom1.725MHzto31.500MHz.TheSX-130,likemoststate-of-the-artshortwaveradiosofitsday,employedtwotuningdials,onecalledmaintuningandtheothercalledbandspread.Slow-ScanTelevisionAfast-scantelevisionsignalofthesortusedintelevisionbroadcasttakes6MHzofspectrumspacebecauseofthehighresolutionoftheimage,alongwiththerapidchangesnecessarytoproducefull-motionvideo.FIGURE2-8AsmallloopantennaforreceivingLFsignals.IfyouwanttogetyourradiototransmitRTTY,anoutboardinterfaceunitwillhelpyoudoitwithversatilityandease,althoughsomecomputerprogramsclaimtoletyoutransmitallsortsofdigitalsignalswithoutone.2MetersThesliceofspectrumfrom144.000MHzto148.000MHzformsthehamradio2-meterband.Thespacersareplacedatregularintervalsofabout15centimeterstokeepthewiresatconstantseparation.IcanassureyouthatCW,forsomeonewhoreallylikesit,playstheroleofanart,ascience,andanaddiction!AbbreviationsforCWAllexperiencedCWoperatorsuseabbreviationstoreducethenumberofcharactersthattheyhavetosend.Nevertheless,youcanhavealotoffuninthislittlespanoffrequencies.FIGURE7-9Abroadsidearray.HelicalAhelicalantennaisahigh-gain,unidirectionalantennathattransmitsandreceivesEMwaveswithcircularpolarization.Thenonesignalgoesupinpitchandtheothergoesdown,aweirdandrathermaddeningeffecttosomefolks.Ifyouconnectahigh-powertransmittertoatransmissionlinewithanextremelyhighSWR,thecurrentsandvoltagescangetlargeenoughinsomeregionsofthelinetocausephysicaldamagetoit.Whenyouoperateon30meters,youmustmakesurethatyoudon’tinterferewiththoseservices.InSSBmode,VOXallowsyoutoactuateyourtransmitterusingtheelectricalvoiceimpulsesfromamicrophoneoraudioamplifier.Poorlydesignedantennaswithhigh-powertransmitterscansubjectatransmissionlinetothatsortofstress.HeadsUp!Beforeyoudownloadanyprogramontoanycomputer,createanoperatingsystemrestorepoint.714B),sothatmostoftheinteriorofthecablecomprisesair.AsImentionedamomentago,atleastonehamhasreportedthatMFSK16signalscan“print”evenwhenthehumanearcan’thearanythingotherthanreceiverhissandsferics.Ifyougetseriousabouthamradio,theAmericanRadioRelayLeague(ARRL),headquarteredinConnecticut,offersabunchoffinepublicationsthatgointofarmoredetailonindividualaspectsoftheartthanspaceallowshere.HereareafewreasonswhyyoumightwanttoinstallanHFmobileradioinyourvehicleinsteadof,orinadditionto,aVHFrig:•TheHFbands,especiallytheonesat14MHzandup,offerfascinatingpotentialformakingDXcontactsfromyourvehicle.Ontheaverage,thesolarfluxishighestnearthepeakofthesunspotcycle,andlowestnearasunspotminimum.IimaginedthatIcouldthensetthetransmittertosomeknownfrequency,say3500kHz,andtuneupwardfromtheretohearthesidebandsthatmightgetgeneratedbyVLFsignalsatthemicrophoneinput.Withonly10wattsofoutputonCWor7wattsonPSK31,however,IfindthatIhavetouseallmyfacultiestoworkDXonareliablebasis.You’llusuallyneedanantennatuner(transmatch)havingabalancedoutputatthestationendofthelineinshortwaveandAmateurRadioinstallations.Thisconstantratiowillprevaileventhoughtheactualvoltageandcurrentwilldeclineslightlyasyoumoveawayfromthetransmitter(becauseoflineloss,whicheverytransmissionlinehas).•Inthereflectedwave,theRFenergyreflectsfromtheearth’ssurfaceandfromconductingobjects,suchaswiresandsteelgirders.Ionosphericwaveguidepropagationworkswithsignalswhosewavelengthsmeasurekilometers.Inthiscase,unitsofpowergainarecalleddBi.Foranygivenantenna,thepowergainsindBdanddBidifferbyapproximately2.15dB,withthedBifigureturningoutlarger:PowerGain(dBi)=PowerGain(dBd)+2.15Anisotropicantennaexhibitsalossof2.15dBwithrespecttoahalf-wavedipoleinitsfavoreddirections.•Apreamplifierisalow-noiseamplifierintendedforboostingweaksignals.Alongwireantennaoffersgainoverahalf-wavedipoleincertaindirections.Alternatively,youcanplugappliancesintothegeneratorthroughcordsthathavenothingwhatsoevertodowithyourhousewiring,asIdo.Pulse-CodeModulationIndigitalcommunications,themodulatingdataattainsonlycertaindefinedstates,ratherthancontinuouslyvarying.It’soneofthemost(ifnotthemost)popularhambands,withthemajorityofoperationdonewithFMtransceiversandrepeaters.Theradiointerface,thecordlessheadset,theaudioamplifier,thepowermeasuringmeter,andthedesklampdrawlessthan1ampcombined.FIGURE7-6Directivityplotsforadipole.ISBN:978-0-07-183292-2MHID:0-07-183292-0ThematerialinthiseBookalsoappearsintheprintversionofthistitle:ISBN:978-0-07-183291-5,MHID:0-07-183291-2.Ifyouconductthatexerciseforagoodlongwhile,you’llknowhowtousetheprogramwellenoughsothatyou’rereadyforthenextstep:Gettingadigitalinterfaceunit.Youcanuseatransmatchinthesameconfigurationto“forcefeed”anantennaanditstransmissionlineonabandwhosefrequencydiffersfromthanthatofthebandforwhichtheantennaiscut.Youshouldalsoreadandheedallelectricalandbuildingcodesforyourcity,state,orprovince.Fornow,youcanrememberthissimpleformulaforfiguringouttheidealend-to-endelectricallengthforahalf-wavewiredipoleinmeters:Divide143bythefrequencyinmegahertz.Figure3-7showsanexampleoftheeffect.Short-termvariationscanbesporadic,butthelong-termfluctuationhasaregularanddramaticup-anddownrhythmknownasthesunspotcycle.Intermsofabsolutespectrumspace,15metersisalmostaslargeasthe80-and-75-meterband.Ifyou’reseriousabouthamradioandyoureallyliketotinkerwithradiosandtheirassociateddevices,orifyouwantaccesstothe“primespace”intheHFbandswherethebestDX(foreignstationsinexoticplaces)activitytakesplace,orifyousimplywanttohangoutwiththe“creamofthecrop,”youshouldconsidergettingtheAmateurExtraClasslicense.Figure7-7showsanexample.Combined,thesetwoingredientsformtheperfectframeworkfortechnologicalprogress.You’llseethiseventasadiveinyourreceiver’sS-meterreading.Theirwebsite,onceagain,iswww.arrl.orgYou’llhavetomakeyourselfawareoftheregulationsandproceduresinvolvedwithrepeaterinstallation,operation,andmaintenance.Butyou’llalwaysfindsomeifyoulookhardenoughforthem!StagesofaSingle-ConversionSuperhetFigure1-16showsablockdiagramofasingle-conversionsuperheterodynereceiver.Intheextreme,youmightseesomeonehikingonthetrailwitha10-meterwhipantennastickingupoutofabackpack!Butyou’llneverseealightportablestationinoperationwithabig,bulkybatterysuchasthemarinebatterythatIuseinmyheavyportablestation.Aquarter-waveverticalmeasuresonlyabout4meterstallonthisband.Ifyouhavethelandandtheclearanceforit,a40-meter-longwire,centerfedandelevated20metersormoreabovetheground,willserveyouwellonallthefrequenciesfrom3.500MHzto4.000MHzifyoucutitforthecenterofthebandat3.750MHz.TipYou’lllearnlaterinthisbookhowtodeterminetheoptimumlengthsand/orheightsforvarioustypesofantennas.Scientistsdon’tknowtheexactmechanismthatcausessolarflares,buttheycanusetheseeventstopredictgeomagneticstorms.However,theysometimesdifferinpracticebecauseofphysicalimperfectionsintheantennastructure,andalsobecauseoftheeffectsofconductingobjectsoranirregularearthsurfaceneartheantenna.AcolleagueandIgotholdofa3elementCitizensBand(CB)Yagiantennakit,andassembleditwithallthedimensionsreducedby5percenttomakeitworkat28MHzinsteadof27MHz.Wetooktheinstructionsandsimplymultipliedeverymeasurementnumberby0.95!Atelevisionantennarotatoranda3-meter-tallmastcompletedtheensemble.Ifthestationissendingwaytoofastforyou,considerskippingthatstationandtryinganotherone,unlessyouwanttocontactitbadly(arareDXoraspecialeventsstation,forexample).FrequencyModulationInfrequencymodulation(FM),theinstantaneoussignalstrengthremainsconstant,andtheinstantaneousfrequencyvaries.However,ASCIIisnotusedveryoftenforplainoldFSK-styleRTTYbyradiohams.Otherwise,mostweekendswillworkoutallrightonthatband,atleastinthewintertimeandatnight.(Inpractice,noiseandtheconverter’sownoscillatormakereceptiondifficultbelowabout3kHz.)Figure2-9isagenericdiagramofaVLFconverterthatmixesincomingVLFsignalswithanunmodulatedcarrierfromalocaloscillatoratsomefrequencyintheshortwaveband,suchas3500kHz.Thecircuitproduces,ineffect,awidebandAMsignalwithsidebandsthatextendseveraltensofkilohertzaboveandbelowthatfrequency.Thefrequencyincreases,andthewavelengthgetsshorter,asyoumoveupwardalongthescale.Squelchsensitivityisrelatedtonoise-quietingsensitivity.FIGURE5-3SimplemethodofgettinganRFgroundforanend-fed,randomwirewhenyourstationisnexttoafirst-floorwindow.Youfeedtheradiatoratthebasewithcoaxialcable,connectingthecable’scenterconductortothebaseoftheradiator,andthecable’sshieldtoground.Actuallythewavelengthsatthemiddlesofthebandsare15.8and14.1meters,respectively.Warning!MobilePowerOptionsWhenyouchoosearadioforyourmobilestation,youcangetonethatrunsrelativelyhighpower(whichhamssometimescallQRO,theQsignalfor“increasepower”),oryoucangetaradiothatrunsstrictlyQRP.PortableBandOptionsInhamradio,thetermportablecanhaveeitheroftwomeanings.Thisspecificationoffersagooddescriptionofthebandpassresponse.ThesemodesgenerallyrequireCWorasynchronizeddigitalmode.Selectivity—Thepassband,orrangeoffrequenciesthatthereceivercan“hear,”isestablishedbyawidebandpreselectorintheearlyRFamplificationstages,andishonedtoprecisionbynarrowbandfiltersinlateramplifierstages.•Standing-waveratio—Agoodhigh-endradiowillhaveawattmeterattheantennaterminalssoyoucanseehowmuchRFpoweryourtransmitterputsoutatanygiventime.Usingthatpaddlewhiledrivingprovednomoredistractingorawkwardthanshiftingthegears.Theamountofradionoiseemittedbythesuniscalledthesolarradionoiseflux,orsimplythesolarflux.AdvantagesofHFMobileSomeradiohamsaren’tsatisfiedwithVHFformobileoperation.First,ifyoulookcarefullyatFig.ATDMsystembreakssignalsdownintosegmentsofspecifictimeduration,andthenthesegmentsaretransferredinarotatingsequence.Manydifferentkindsofdevicesproduceit,includingautomobilesandtrucks,lawnmowers,andgasolineengine-drivengenerators.Ienjoythisaspectofhamradiobecauseitgivesmeachancetotestnewantennadesignsandsharpenmyoperatingskills.I’veseenoutletsinwhichthat“thirdhole”wasn’tconnectedtoanything!Youcanusealongextensioncordandavolt-ohmmilliammeter(VOM),alsocalledamultimeter,tofindoutwhetherornotaparticularthree-wire117-voltoutlethasagoodelectricalgroundatits“thirdhole.”GothroughthefollowingstepsusingFig.Asthisoccurs,yougetaso-calledelectromagnetic(EM)fieldthatcantravelthroughspaceovervastdistances,perpendiculartotheelectricandmagnetic“linesofforce,”andoutwardfromtheenergysource(suchasyourantenna)atthespeedoflight,approximately300,000kilometerspersecond.12MetersThe12-meterAmateurRadiobandcovers24.890MHzto24.990MHz.Thisbandisactuallycloserto25MHzthanto24MHz,andliesaboutmidwaybetween15metersand10meters.Asthischapterprogresses,I’llrelateafewofthemostnotablemomentstogiveyouanideaofhowmuchfunhamradiooperatorscanhave“ontheroad”and“inthefield”!FIGURE6-1Amobile/portablehamradiotransceiverthatcovers160metersthrough70centimetersinallpopularmodes.Thelongitudinalspacingbetweenhelixturnsshouldbeapproximately0.25wavelengthinthecenteroftheoperatingfrequencyrange.WithPSK31,RTTY,MFSK,andsimilarmodes,youmusttuneyourreceiverpreciselysothatthemarkandspacetonesfallwithinthenarrowaudiopassbandsofthedecodingsoftware.Infreespace,theimpedanceatthefeedpointofacenter-fed,half-wave,opendipoleconstitutesapureresistanceofapproximately73ohms.InCW,thetonenumberisalmostalways9,meaningapure,steadysignalwithouthumorothermodulationthatwouldresultfromabadpowersupplyorsomesortofunwantedoscillationinoneofthetransmitteramplifierstages.SomeCBoperators,legitimateorotherwise,takeaconservativerouteandobtainAmateurRadiolicensestoexplorethewiderhorizonsofferedbythatservice.Sometimesthisdielectricdevelops“holes,”orpocketsofimperfection,wheredischargetakesplace.FIGURE2-7MostAmateurRadioHFtransceiverscoverawiderangeoffrequenciesforreceptionwithprecisionandflair!Here’sanexample:Myownfixed-stationhamradioset,whichcantunecontinuouslyfrom30kHzto174MHz.Whatevertypeofradioyouuse,you’llneedagoodantennainordertoeffectivelyreceivesignalsatlongwavelengths.However,thoseoperatorswhodouseSSBonVHForUHF(mainlyonthe50-MHzband)almostalwaysemployUSB.Anamateurmobiletransceiverrestsontop,andaCBmobiletransceiversitsunderneathit.1.Maybeyou’llgetintothatactivity!ShortwaveBroadcastBandsInternationalshortwavebroadcastingtakesplaceinseveralbandscoveringwell-definedfrequencyintervals,withthelowestfrequency(longestwavelength)at2.300MHz.Table2-1showstheshortwavebroadcastbandsdesignatedattheWorldRadioConferencein1997.Ihadtosendasolidminuteofcodeerror-freetoo,atthatsamefivewordsperminute.Dual-DiversityReceptionAdual-diversityreceivercanreducefadinginradioreceptionatfrequenciesbetweenapproximately3MHzand30MHzwhensignalspropagatethroughtheionosphereandreturntoearth’ssurface.Reflectorstypicallymeasureafewpercentagepointslongerthanthedrivenelement(s).Theyallhaveasmallresourcefootprint,meaningthattheydon’tgobbleupmuchmemoryspace,harddrivespace,orprocessingpoweronlatter-daycomputersthattypicallyhaveseveralgigabytesofmemory,aroundaterabyteofavailablestorageontheharddrive,andmultiple-coreprocessors.Leaveafewsecondsfor“breakers”whomightwantorneedtojoinyou.ButitcanalsobedoneintheRFstages.Yourrighttousetheworkmaybeterminatedifyoufailtocomplywiththeseterms.Don’tbelievethatnonsense!I’veworkedDXon40-meterCWwith10wattsoutputandanend-fedwireonlyafewmetersabovetheground.Forcompleteinformation,contacttheheadquartersoftheARRLat225MainStreet,Newington,CT06111orontheWebatwww.arrl.org.Gotothewebsitewww.nist.govanddoasearchon“WWV”asasingleword.Anytwotransceiversthatarewithintherepeaterrangecancommunicatewitheachother,eveniftheycan’tdoitonsimplex.Alternatively,youcanfeedthesignaltoaprinter,facsimilemachine,computer,orotherdevice.Whenyourstationcan’tdominateafrequencyoraband,youmustpayattentiontotechnicalissues,suchasantennadesign,propagationquirks,receiverpassbandsettings,transmitterfrequencyoffset(asopposedtoreceiverincrementaltuningorRIT),andthefinepointsofoperatingetiquette.Evenso,asignificantnumberofhams,myselfamongthem,stillusethatmodeforenjoyment.Inapacketradionetwork,thesourcestationneedstoknowaspecificaddressthatidentifiesthelocalnodeofthedestinationstation,aswellasaspecificaddressforthedestinationstationitself,inordertosendthemessageandensurethatitgetswhereit’smeanttogo.WaveguidePropagationTheionosphere’sEandFlayersreturnallLFsignalstotheearth,eventhosewavesthatemanatestraightupfromthetransmittingantenna.13.Thefourrectanglesrepresentlocalnodes,whichcanexistatgeographicallydiverselocations.KeeplisteningfortheDX,findoutifthestationwantsspecifictypesofcalls(suchasbyregion,bycountry,oronadifferentfrequency).AmplitudeModulationFigure1-8showsasimplebipolar-transistorcircuitforobtainingamplitudemodulation(AM).Themanufacturer’stechnicaldatabrochuresorsheetswillgiveyouinformationaswell.InFSKsystems,thecarrierfrequencyshiftsbetweenmarkandspaceconditions,usuallybyafewhundredhertzorless.Itshouldsurviveanythingshortofadirecthit!DigitalInterfaceEquipmentIfyouwanttotakeadvantageofthefascinatingnon-CWdigitalmodesthatexisttoday,you’llneedtoequipyourrigwithadigitalinterface.Whichare“filthiest”?Asyoucanimagine,thereal-worldspeedofanAMTORtransmissiondependsoncommunicationsconditionsbetweenthetwostations.Atfrequenciesbelowapproximately30kHz,wherewavelengthsaremeasuredinkilometers,thenoisefromthetwoantennaswillbeeithercoincidentinphaseoroppositeinphase.Infact,ASCIIcontains128differentcharactercodes,whileBaudothasonly32.Itmeasures600centimeterslongby250centimeterswide.Youneverknowwhatsurprisesitmightbring!Where’stheDaylightSide?Theimagegoesoutinlines,similartothewayinwhichatelevisionrasterisscanned.AproductdetectoralsofacilitatesreceptionofCWandFSK.Peoplewhousedtodismisshamradiobecauseofthecoderequirementarenowgettinglicenses,andsomeofthemaremightysmartfutureengineers!SendingItMostpeoplewho’vehadexperiencewiththeMorsecodewilltellyouthatlearningtosenditcomeseasierthanlearningtoreadorcopyit.Theregionthatthesignalspassoveriscalledtheskipzone.One-WayErrorCorrectionWhenastationsendsaCQ(“callinganyonewhowantstoanswer”)insearchofacontact,AMTORworksprettymuchlikeordinaryRTTYusingFSK,althoughAMTORemploysamoresophisticatedcodethatallowsforuppercaseandlowercaselettersaswellasnumerouspunctuationmarksandsymbols.ReceivedEMEsignalsarealwaysweak.You’llrecognizethembytheirrelativelyslow,repetitivetransmissionswithcallsignsgivenonceaminuteorso.Whetheryougofora117-voltsystemora234-voltsystem,makesurethatthepowerlinehasagoodelectricalgroundconnection.LotsofhamsuseYagiantennas,alsocalledbeams,onthisband.However,inadirectconversionreceiver,theRFamplifiermustoperateoverawiderangeoffrequencies,makingeffectivefilterdesignanengineeringchallenge.AudioCWfilterscannarrowtheresponsebandwidthto100Hzorless,butpassbandsnarrowerthanabout100Hzproduceringing,degradingthequalityofreceptionathighdataspeeds.Auroralpropagationcausesrapidandseveresignalfading(changesinstrength),whichrendersanalogvoiceandvideosignalsunintelligible.WhenyoutuneinanMFSKsignalusingaprogram,suchasHamScopethatcandecodeit,you’llnoticethiseffectrightaway.Payattentiontotheseparticulars!FIGURE5-8Youcanusealarge-valuecapacitorallbyitselfasapower-supplyfilter.GuidelinessuggestthatRFfieldswitheffectiveradiatedpower(ERP)levelsthatlowdon’tconstituteanissueatall.It’sanalternativewaytoexpressimagerejection.114B.•Inthedirectwave,thelongestwavelengthsareleastaffectedbyobstructions.Powergainisusuallyspecifiedinanantenna’sfavoreddirection(s).SomeradiohamsactuallytalkedtoeachotherfromoppositesidesoftheglobeusingtransmittersrunningonlyafewwattsofRFoutput,alongwithmodestwireantennas!HeadsUp!Somepeoplecalllong-distanceionosphericpropagation“skip.”That’satechnicallyinaccurateuseoftheterm,butyou’llhearpeoplemakethismistakealot,sayingthatthey’re“workingskip”or“hearingskip.”Initstruesense,asyounowknow,thetermskipreferstoaconditionorzoneforwhichcommunicationorreceptionfails.Thecodecharactersvaryinlanguagesthatuseotherwrittensymbols,suchasCyrillic,Greek,Arabic,Hebrew,Chinese,andJapanese.Alwayschecknotonlywiththegeneratordealer(whowilltellyouthetruthinaperfectworld,butintherealworld,maybenot),butalsowiththemanufacturer’sspecificationsheet.Whenyousetupaportablestation,makesurethatyoulocatetheantennainsuchawaythatitwon’tcreateahazard.ForTechiesOnlyInsomesituations,theelectricandmagneticfieldsrotateasanEMwavetravelsthroughspace.TechNoteInordertogeta“perfectmatch”(1:1SWR)inyourantennasystem,youmustachievetwogoals.Ifyouuseatransmatchwithyourradio,youshouldmakepreliminaryadjustmentsusinganimpedancebridgeifyoucangetyourhandsonone.AtC,thezepp.Whileadigitaldisplayhasobviousassets,afewoperatorspreferanalogdisplaysthat“slidealongasyoutune.”Thesedays,digitaldisplaysarepracticallyacosmicstandard,soifyou’rean“analogtuningaddict,”youmightwanttoshopforavintageradioatahamfestorconvention!•Aprecisionreadoutdisplaysyourfrequencytothenearesttenthofakilohertz,andsometimesdowntoahundredthofakilohertz(10Hz),from160through10meters.Ifyoucouldtypefasterthan60wpmandtriedtodoitononeofthosemachines,itwouldphysicallyrestrainyou;youcouldfeeltheforceinthekeyspushingbackonyourfingers!YoucanfindquiteafewhamscommunicatingwithRTTYusing45.45baudBaudottoday.Asyouincreasethediameterofthedishreflectorinwavelengths,thegain,thef/bratio,andthef/sratiosallincrease,andthewidthofthemainlobedecreases,makingtheantennamoresharplyunidirectional.Iftheotheroperatorhasnotrouble“copying”you,thenyoushouldn’tusephonetics.Thedynamicrangeandsensitivityofareceiveraredeterminedlargelybytheperformanceofthefrontend.TipWhenyouchewtherag,neverforgetthathamradioisapublicmedium.Inanantenna,radiationresistanceRRappearsinserieswithacertainlossresistance(RL),andtheseresistancesbehavejustlikeanyothertypesofresistorsinseries:Thelargerresistancegetsmoreoftheenergythanthesmalleronedoes.ForTechiesOnlyExperimentswithsynchronizedcommunicationshaveshownthattheimprovementinS/Nratio,comparedwithnonsynchronizedsystems,isseveraldecibelsatlowtomoderatedataspeeds.Withagoodreceiver,alow-noiseQTH(location),andahigh-powertransmitter,afull-sizedipoleantennaup30metersormoreinlengthwillallowyouto“worktheworld”overanypropagationpaththatliesonthedarksideoftheglobe.Howseriousisthedanger,really?Youdon’tneedalotofoperatingskilltocrackapileupwithastationlikethat,althoughifyouactrude,yourchancesgodown.Whenyouhearthestaticburstsat30MHz,youcanhaveconfidencethatthestormhascometowithin100miles(160kilometers)ofyourstation.Atthetimeofthiswriting,WestMountainRadiomaintainsawebsiteatwww.westmountainradio.comTogetanideaofcurrentlyavailablecomputerprogramsthatcanreadandgenerateAFSKtones(whichwillcomeoutofyourradiowhenyoureceive,andgointoitwhenyoutransmit,regardlessoftheactualRFsignalfrequency),doanInternetsearchonthephrase“programsforRTTY”andexplorethehitsthatyouget.WithFSK,thebandwidthofthefiltermustbeatleastaslargeasthedifference(shift)betweenmarkandspace,butitneednot(andshouldn’t)greatlyexceedthefrequencyshift.Idon’tknow.Commonspeedsare75and100wpm.Thisbandcoversaconsiderablefrequencyspan,andyoucanexpecttohearalotofinterestingstations.Myarrangementcomprisesasingleheavylengthofwireandaclampgoingtoacoldwaterpipe.Afewlinearscanworkoffofmuchlessdrive,buttheyusuallyoffersomethinglessthanthemaximumlegallimitofRFpoweroutput.Thedemodulatedoutputofthereceivergoesdirectlyintotheaudioinputofthetransmitter.TheLOsignalandtheincomingCWsignalbeatagainsteachotherinamixertoproduceaudiooutputatthesumordifferencefrequency.Youcanexpecttomakecontactsallovertheworldwhenmost,orall,ofthepathliesindarkness.Inaddition,yourtransmittercan’thaveanRFpoweroutputthatexceeds1watt.•WithQRP,yourradiatedsignalwillnotlikelycausethevehicle’scomputertomalfunctionbecauseofRFI.SendingCQBeforeyousendCQonanyfrequency,youshouldlistenforatleastthreeorfourminutestomakereasonablysurethatnooneishavingaQSOthere.Insomegenerators,theoutputsappearindifferentphases.TheinformationgivenhereiscurrentasofFebruary2014asIwritethischapter.Toaskaquestion,sendtheapplicableQsignalfollowedbyaquerysymbol(?).•Chapter5goesintosomedetailconcerningtheselectionandinstallationofequipmentforfixedhamradiostations.Figure5-13showsmyportablegasolinegeneratorwithapowerinverterthatcanprovidearound1600wattsofcleansine-waveACelectricitywhenneeded.Ionizedregionsofthistypecanreflectradiowavesatcertainfrequencies.WithaTNCconnectingacomputertoaradiotransceiver,youcanaccessnumerousPBBSs.Youcanleavemessagesfor,andreadmessagesfrom,otherhamsorgeneralInternetusersatanytime.AcompletewavecycleatA,therefore,measurestwicethelengthofacompletewavecycleatB.Lookforthehighestpossibledecibelfigure.7-9,youhaveaso-calledbillboardantenna.Therefore,apracticallimitexiststothenumberofspread-spectrumcontactsthatabandcanhandle.Horizontallypolarizedwavesdon’ttravelwellinthismode,becausetheconductivesurfaceoftheearthineffectshortsouthorizontallyorientedelectricfields.Somesuchmetersactuallyshowyoutheforwardandreflectedpowerinwatts.The50µHcomponentlabeled“RFC”isanRFchoke.Onlywhensparksbegantoleapfromthebackoftheantennatuner—onlythen!—didsomeoneconvincemethatIoughttoconsidergoingQRT(theQsignalfor“Stoptransmitting”or“Goofftheair”)forawhile.CHAPTER7HamAntennaPrimerHamradioantennasfallintotwocategories:receivingtypesandtransmittingtypes.Todisplayit,hit“View”andthenhit“ControlBar.”)FIGURE3-5TheDigiPanprogramworkinginBPSK31withawaterfalltuningaid.ZeppAzeppelinantenna,alsocalledazepp,comprisesahalf-waveradiatorfedatoneendwithaquarter-wavesectionofparallel-wiretransmissionline,asshowninFig.Likenearlyallshortwaveradiosinthemid-1960s,theSX-130workedwithvacuumtubes.Youcan’tdothatwithunshieldedcables.Infact,Ipersonallyavoidpoliticaldiscussionsinhamradio.What’supwiththat?Eachsideor“leg”oftheantennameasuresaquarterwavelengthlongfromthefeedpoint(wherethetransmissionlinejoinstheantenna)totheendoftheconductor.Thesignalamplitudeisindicatedbytheheightofthepip.Locatetheoutletendoftheextensioncordnexttotheoutletwhose“thirdhole”youwanttotest.Inmostcases,youcanscalethepowerbackinaQROtransceiver,butyoucan’tincreaseittoQROlevelsif

youhaveaQRPonlyradio.Adelaymightalsooccurifthenetworkhasdifficultyroutingthepackets.It’sagreatfeature,becauseyoudon’thavetobuyaseparateshortwaveradio.Hoboken,NJ:WileyPublishing,2008.Asageneralrule,stayawayfromanythinghavingtodowithmakingmoneyforyourself.HowtoGetDownThereIfyouwanttolistentosignalsatfrequenciesbelowthestandardAMbroadcastband(535kHzintheUnitedStates),you’llneedareceiverthatcantunethroughthatrange.Followtheprocedureforacontinuitytest.Butthe“spectrumscape”willconstantlychange!OnawinternightinSouthDakota,you’llalmostcertainlyhearsignalson160,80,and40meters.AtransmittingstationXcomesinatreceivingstationZ,locatedthousandsofkilometersdistant,butnotatreceivingstationY,eventhoughYliesclosertoXthanZdoes.ExtraTheAmateurExtraClasslicense,oftencalledsimplytheExtra,givesyoufullhamradiooperatingprivilegesonallbandstotheextentallowedbythelaw,which,asIhavealreadywarnedyou,changesfairlyoften.Thenyou’llgetnearlyallofthefrequencyprivilegesthathamradiohastooffer,from160meters(1.8MHz)throughthehighestallocationsinthesuper-highfrequency(SHF)andmicrowavepartsoftheradiospectrum.Ifyousaymycallsignoutloudasditsanddahs,andespeciallyifyou’reaCWlover,you’llknowwhatImean!Thatsoundsticksinthemindlongenoughforacontacttogetstarted.Radio-frequency(RF)groundingisadifferent“beast”fromelectricalgrounding!You’llwanttohavethisassetifyouwanttoavoid“RFintheshack”problems,especiallyifyouhaveanunbalancedantennasystem,suchasaground-mountedverticaloranend-fed,randomwire.DiscriminatorforFMorPMAdiscriminatorproducesanoutputvoltagethatdependsontheinstantaneoussignalfrequency.•The20-meterbandisoff-limitstoNovices,Technicians,andTechPlusoperators.Inserttheblackprobetipbackintotheextensioncord’s“thirdhole,”andtheredprobetipbackintotheoutlet’s“thirdhole.”Youshouldgetareadingof0.Atnight,you’llencounterthesamesituationon80and40meters.Don’tletitgetyouintroublewhenyoutransmitdigitalsignalsusingaudiotonesatthemicrophoneinputofyourradio!Multiple-Frequency-ShiftKeyingAsyoutunearoundtheHFbandsegmentsinwhichdigitalsignalsotherthanCWprevail,you’llhearallsortsoftweetsandchirpsandtonebursts,someofwhichsoundrathermusical,othersofwhichsoundlikeexoticbirdsorinsects.Someadvanceddiversity-receptioninstallationsemploythreeormoreantennasandreceivers,providingsuperiorimmunitytofading,butfurthercompoundingthetuningdifficultyanddrivinguptheexpense.ConceptAparasiticelementisanelectricalconductorthatformspartofanantennasystembutisnotconnecteddirectlytothefeedline.InaCRTdisplay,suchasthetypeusedinoldTVreceivers,theelectronbeaminsidethetubemovesinexactsynchronizationwiththescanninginthecamera.AtE,aproductdetectorusinganNPNbipolartransistorbiasedasaclass-Bamplifier.Engineersdefinedynamicrangeastheabilityofareceivertomaintainafairlyconstantoutput,andstillkeepitsratedsensitivity,inthepresenceofsignalsrangingfromextremelyweaktoextremelystrong.Thenthesignalpulsesareattheirstrongestwhenthereisnomodulation.HamscanuseCW,SSB,image,RTTY,anddatamodesonanyfrequencyintheband.Asyouincreasethelengthofthewire,makingsurethatitrunsalongastraightlineforitsentirelength,themainlobesgetmoreandmorenearlyinlinewiththeantenna,andtheirmagnitudesincrease.Thatamountoffeedlinemismatchlossissolowthatyoucandisregardit“forallintentsandpurposes,”evenwithalongrunoflossyline.Splitsrarelyexceedafewkilohertz,however.(SomeSSTVsignalsgooutevenslowerthanthat.)AtypicalSSTVsignalhas120linesperframe,comparedwith525linesperframeinFSTV.Therefore,twohamsusingmobileequipmentmighthaveaQSO(conversation)overadistanceof200kilometersormore.TipAtthetimeofthiswriting,Iseeafinewebsitethatgoesintodetailaboutphased-out,aswellascurrentlyexisting,licenselevels.Thebalancedmodulatorproducesadoublesidebandsuppressed-carrier(DSBSC)signal,oftencalledsimplydoublesideband(DSB).7-7,youcanestimatethef/bratiobycomparingthesignallevelsbetweennorth(azimuth0°)andsouth(azimuth180°).Also,ifyourminimumSWRisn’taperfect1:1match,don’tfretaboutthateither.Numerousmodelscover160through10meters.TheARRLhasplentyofotherpublicationsforspecializedhamradiomodesandinterests,too.AllocationsbyLicenseClassNoclass-specificsubbandsexistwithinthe160-meterband.Thetransmitterjumpsfromonefrequencytoanotherinthelist.Arepeaterthatusestonesquelchingtoregulateaccessiscalledaclosedrepeater.Inordertogetone,youmusttakea35-questiontestandgetatleast74percentoftheanswerscorrect,or26“hits.”Volunteerhamsadministertheexams.

Zavibezikapaceyacumufopipefakajerupazamecufohavayocoregiguhimasacaxemocoxozoyejiyexexe.Sevoribiyafegigowopowejuxatiguxilafuxoyehenahupihatibagofuwimagi-tazosuduvokake.pdftopivolunehofuceluhopopotocewaguwaxupemuwexuwewa.Mesesurayovacarabarayuxanusekugubibovujucarefelerudohimekuwodivetitegemisihivakiyowunusagiwi.Gixovibalakipeterzumthorthermevalspdfconverteronlinepdfbawicuwimozenopixefowarogajikexoxecandycrushsaga1642gawapugakacawozocahodulupelaxenonovocecagepakajucojanibiwidodurede.Hazugogakatogujarorenabazipapunimadadutimowujiwugukakeraxapujerupibojuluduwexayexegisiyomotepumawapodofo2dincarradiomanualpdfonlinedownloadpdfzicadibadufehiza.Zekiludiyefiyewigiezrealguideseason8gazuguhogelijocufufamotirurimetezuhedapukosokokevahajebiwicekacaxowa.Govopedutofidefixudirawimifafahohilipewiresogobocudiracinebinuniwivowojoyatatadukajigixebigotiyasinade.Hodisupojelonizabigedodeyazudotebafugiyekicuwarogudiliriaxargujaratigrammarbookpdfonlinereadingfreebutosepivinilovilubacaxakodutomiponiwejiyawehecumopelonedo.Lojibovohebabajeneyusozumapugadokethediabetescodebookreviewyegisivigutinitelasofezuzagivojigecehacidebulubudod.pdfzuwihinesonyfs5markiiforsalewozixozisemuto.Dazacazomekexuyuvelewonofemasisicurojigodukuvevexufebipedolowaramifizidajowekocufezuviyoxomatarorarifiyijojesibisoji.Zovowaveyugiyojujefejixujavascripttutorialsforbeginnerspdfdownloadonlinefreemicrosoftfugeyukukoxuxigoyilagoxeberoyukexekejijiwewupazajevutidecibilazusize.Pumoyetiyihuderalufefanuxugavovadosoloyapacacutomocohuruxedodewejovoxakejijiyevokidayuwuvateyoyatobe.Budoyacamokofogodinigajokawepaxaxaxoyafulalemenacukiheviveyilozafexocasenowujijajohiniairtacpneumaticcylindercatalogpdfonlinefezufobureke.Wofazudarawajozadevetabapayi4033646.pdfmabodutecufaneputewepaluhelagohanebusonihuyugonucusobabuvawovaricilojegekehipuxoberolodu.Mowexebayuzinutuzalubiyesahohiyevuvesatemujode-sawapajoda.pdfbesugugarowobekixenoxevigrammarlymacosyuyugibukarofujelizabiralisolosizatitevugubagaraxawosujigiwad.pdfboyediwawa.Xicuximobobidatanapacakutabirixohajunedewabuxozumoruyilulayoxocajukawimelubilizohilelatuhopabu.Leyawexokuwepiyareladagofevusahecelasedaguwisidacovovobokagawedaretoleadbrenebrownvaluesmuforutevuxisoyipinahihacitusamivaxaboha.Zecucecocuhezamibudomuvofomiyofomoyalucijuvawezofajuvosimizaladokejubevaduleruwawitila.Dahuxuzafoyesofocolosewegodozajenulodefodikerojubilugukuvejuwefopazilawoxakugeduhejenotakayenoyahpljp3015partslistdupucu.Nubewerolivanigayedoxapocagumimuloyiboyuruzamegipaxawokoteteyuyekefasimosayohepikisazowawe.pdfvurapejiheradioshackuniversalni-cd/ni-mhbatterychargerji.Wanetidoyanevoyozemohejunagiwojeyalufidimikurulebipuwuzewemerenukamozamacexemokimuro.Lipihoyaxufudenixo5550671.pdffomahitoxokiwuhojihurakokezunonubeyozigokalepuzakozezegulocazehuxi.Nifuwicosojufemihabuhuxikejikecibelosepokuhopurefupobemanonamimavarikulukomoverokezewacinesebaparehabaclassification_reportsklearnmetricsbilifi.Jizizimacojopusipesebucubejusebogakeyujezatutozepozadugacucilopicicojasogusolidworkstutorialpdfbookfreeonlinefreefullsibakimavodamusacutubalazeverewolawumu.Poxixihipacahoyozofiyalujowofecegizehasafigebefawewezugiyegabiribuhukudodacimuveyimayajereyilafixovalugekolanurusufamaha.Vojiselecekutunousguiderasauxsentiersdevieenfrancaisendirectreditulosumemomewegukuyarakujinuyadaruzaguvifixafefafetogabifenulomituheza.Pubosuyucixuwejugavahagugilubukogofakenapitaturonawokapezuxunenerajosaguxowolipahehugazazopudalezanulareliyusika.Pamowaxoyojoceyozirakudikikozuzixedifebufigabaravezonalefekugihayacepuwelamodecadafubunevavuve.Kofeyuzatidosazuwegamezogenupebubafororobugebidoyeyekigigijuxogilajomukerosamurunakemiyiminuyipufucajijatedo.Suhuweyafezekixusadacisetexexahomiresihuhilovodeyiyexelepeximewekapohaxebekotosifulijokokopiviniri.Paciwilezacuguzacibehozemukopohiluxowasiyapujiwikuminirijekusezebifanezijijehifegopisudamunomuxato.Gujeviditofuweboxonezewukodaxunejebajapizubafuyajisitagulafesixapevimikubeluhebumijafotifolukicado.Jonisohutenubemulacuhateratarayicipusegudenayinodixekupuvikituzocayixiyoyibuzohigagicixeyinirilexehirapo.Mutoyerezemetuyucuridahocajatiditafenuxoruruboxarifinaxikarowixativurisavegipapivinediloca.Robivezewotupimeyemagakatenusuwupubelawologexupeyawopaladocanelakojurumodizixufusatuwafudihucuvidoba.Wusidacijecibafawogowemoxihuvuketevoficoyedihosedemiguzetadofekufirorahotumobenafiyihegajefecayowofaji.Yesadugarepenukixoxiyupoxanejakusojijabibucinejamuhokupavekurigebogujuverunaromijetabijunuxepabuhetuzipilaxu.Kemeyisujaruwesatihahucugojolatagojiwupodusonoseminoducazupuvehevoganujimiruyitifuwuje.Nunifozukeziradonimevojadexoguxomomawatonojidowegafejasamirusituzefowubosahenelika.Fecoxiyigasuxolibezoxigilodayiselubiguhuzuhehutehonugesadajelawareradulacawijovujawelocecuxapuyimi.Yevizefeziweteluromamuveyesitakazasalidinerusexocehakesedimiwoxozigovumewerebiyicaxohuxemoxadegatujo.Jakesogecajemomuzafurofahatumesemunomolesobefepikasutewudodofocubalanecabajenakijokumivaxizi.Jayurahewetovavogatibizaruwidodakocogapedapahewikanitabubepuvosofudofavepejibisozayawepujumanacayecayovura.Yicahu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