REPEATERS SIERRA INTERMOUNTAIN EMERGENCY ASSOCIATION.

REPEATERSREPEATERS

SIERRA INTERMOUNTAIN EMERGENCY ASSOCIATION

WHY REPEATERS?WHY REPEATERS?

1. Extend the range of our low power portables and mobiles.

2. Provides the means for communications throughout a geographic community.

THE SIERA THE SIERA REPEATERREPEATER

• Located on Leviathan peak, about 30 miles south of Gardnerville at about 8900 ft.

• Receives on 147.930 MHz• Requires a PL of 123 Hz• Transmits on 147.330 MHz, ERP 25 watts

LEVIATHAN VIEWED FROM MONITOR PASS HIGHWAY

GEORGE UEBELE AND

WILL LEWISJULY 29, 2005

Leviathan Repeater building

Leviathan equipment room

SIERA repeater

LEVIATHAN SOLAR PANELS

LEVIATHAN LOOKING EAST

LEVIATHAN LOOKING NORTHEAST

LEVIATHAN LOOKING NORTH

LEVIATHAN LOOKING WEST

LEVIATHAN LOOKING SOUTH

TARA REPEATERTARA REPEATER

• Located on East Peak at about 9500 feet• Receives on 147.840 MHz• Sometimes requires a PL of 123 Hz• Transmits on 147.240 MHz

East Peak Antenna Tower

East Peak View of Lake Tahoe

East Peak View of Lake Tahoe to North

East Peak View of South Lake Tahoe

East Peak View to Southeast towards Carson Valley

East Peak View to East towards Carson Valley

East Peak View to Northeast towards Carson City

W7DI REPEATERSW7DI REPEATERS• Located on McClellan Peak, north of Carson City

at about 7400 ft• Two repeaters linked together

• Receives on 147.870 MHz• Requires PL of 123 Hz• Transmits on 147.270 MHz, ERP 100 watts

• Receives on 446.250 MHz• Requires PL of 123 Hz• Transmits on 441.250 MHz, ERP 80 watts

McClellan Peak Antenna Farm

April 13, 2011McClellan Peak North Side of Equipment Building

McClellan Peak W7DI RepeatersVHF in front on bottom

UHF in back on top

MINDEN REPEATER

Receives 448.750 MHz - No PLTransmits 443.750 MHz - ERP 20 watts

Linked to McClellan repeaters

REPEATER REPEATER REQUIREMENTSREQUIREMENTS

• Must be able to transmit and receive simultaneously

• Requires two antennas or a duplexer• Requires a controller• Must meet Site Managers specifications

DUPLEXERSDUPLEXERS• Duplexers allow you to

transmit and receive simultaneously on a common antenna

• Duplexers are made up of 4 or more cavities

• A cavity passes a narrow bandwidth centered on its resonant frequency

DUPLEXERSDUPLEXERS

rTransmitter147.330

Receiver147.930

147.330147.330147.930147.930

COAXIAL CABLECOAXIAL CABLE

COAX TYPEATT/100

FEET AT 2 METERS

POWER OUT WITH 100 WATTS IN

ATT/100 FEET AT 70

CENTIMETERS

POWER OUT WITH 100 WATTS IN

COST/FT

RG58 6 db 25 watts 9 db 13 watts 0.30RG8 1.5 db 71 watts 3 db 50 watts 1.00

1/2" Heliax .8 db 83 watts 1.4 db 72 watts 3.007/8" Heliax .45 db 90 watts .8 db 83 watts 7.00

• Loss in coax cable increases with frequency• Larger cable has less loss than smaller

TARA repeater has 410 ft of 7/8” Heliax with a loss of 1.85 db

CONTROLLERSCONTROLLERS• Must be able to turn the repeater off and on• Must ID at required intervals• Needs a timeout timer

• Other options:o Courtesy toneso Hang timeo Announcementso Auxillary controls

CONTROL OPERATORCONTROL OPERATOR• A control operator is required any time an

amateur transmitter is in operation• For repeater operation, the FCC allows remote

control. The repeater control operator(s) can monitor and control its operation by some form of control link from one or more distant locations.

• A radio control link uses an auxiliary frequency to control the repeater. Auxiliary frequencies must be above 222.15 MHz

• Control codes should be known only by the licensee and control operators

AUTOMATIC AUTOMATIC CONTROLCONTROL

• (Automatic control) the use of devices and procedures for control of a station when it is transmitting so that compliance with the FCC Rules is achieved without the control operator being present at a control point. §97.3 (a)(6)

• In the event of improper use of the machine, the licensee is responsible for correcting the problem as soon as practicable and for making sure that the problem will not happen again (ARRL rule book)

• Although no control operator is required to be present at a control point while the repeater is operating under automatic control, it is still the station licensee’s responsibility to see that the repeater operates properly at all times (ARRL rule book)

FREQUENCY FREQUENCY MODULATIONMODULATION

• Frequency modulation is the process of using an audio signal to cause the RF carrier frequency to swing up and down

• The audio level determines how far the RF carrier swings

• The ideal audio level for ham radios will cause the frequency to deviate by ±5 KHz

COMMON PROBLEMSCOMMON PROBLEMS

• Improper modulation

o Low audio levels will result if deviation is less than ± 5KHz

o Audio levels exceeding ± 5KHz can result in distortion

o Radios and microphones vary in sensitivity

COMMON PROBLEMSCOMMON PROBLEMS• Not enough power

o The RF signal into the repeater is not enough to “quiet” the receiver.

o There will be background noise or you may not “hold” the repeater

o Yelling into the microphone will usually not improve your signal if you have low power into the repeater

o Most repeaters “talk out” further than they can “hear”

PUBLIC SERVICEPUBLIC SERVICE• §97.1 Basis and purpose (of amateur radio)

• (a) Recognition and enhancement of the value of the amateur service to the public as a voluntary noncommercial communication service, particularly with respect to providing emergency communications.

• Our ability to have repeaters located in public facilities is because of agreements with public officials to provide these services.