Racal Loudspeaker Amplifier MA.909

8/19/2019 Racal Loudspeaker Amplifier MA.909

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ΜΑ.909LoudspeakerAmplifier

Racal-TacticomLimited,Ñ,Ο.Βοχ º º 2,472 BasingsτokeRoad, Reading,Berks.RG2ooF.Tel. Reading (0734)83312. Telex: 848Ο1 1 Grams: TacticomReading.Prepared by Central HandbooksDepartment, RacalGroupServicesιimited.

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The ElectronicsGroupPrinted ßη England Ref. 3º θ lssue 3.1 1.78-25


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coNTENτs

ΙNTRODUCΤΙON

CONSΤRUCTΙON

CΙRCUΙΤDESCRΙPTΙON

TESΤΙNG A,ND FAULTLOCATΙON

COMPONENTSLIST

ΙLLUSΤRAΤΙONS

Circuiτ:ΙγÞΑ.909 LoudspeokerAmplifier

ComponentLoyout:ΙýΑ.909LoudspeokerAmplifier

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Ι NTRODUCTΙONANDOPERATIOΝl. The loudspeokerAmplifierUnitprovidesο loudspeokerfacilityfor ο rnonpack.

The power source for the unif is derived from the manpock.The οηΙγ operationrequired to bring the unit into use is to connect the plugοη the unit to one of the AUDIOsockets οη the rnonpack

CONSTRUCTlON2. The omplifier unitis ossembled ßη ο cost metol case as illustrated ßη Fig.2.

The cose is complefelywoterproof . The moiorityof the components of the unitore ossembled οηο printed circuitboord vvhichis mounted ιτßhßη the cose. The bock panelof the cose is removable, and is heldßη positionby four screu/s. Αsealing gasket is fittedbetιyeen the bock ponel and the cose.

CΙRCUITDESCRΙPΤΙON3. The circuit(Fis. l) consists ofο three tronsistor, transformerless poιrer

amplifier,designed to feed υñ to 5Φ mWinto α35 ohm lood. The pσ,verconsumptionof the amplifierat moximumoutput is approximatelyü0 mAfromοη Ι8ýοΙtsupply.

4. The input signol is applied to the base of ο η.ñ.η. transistorTRl,νßα thecapocitor Cl. TRIoperates os ο driver stage for the output transistors TR2ond

TR3connected ßη the compIementory symmetry mode, vlhichoperotes os follows:

5. TR2is α η.Ñ.η. type transistor, connected os αη emitter folto,aer ι^ιßh TR3providingthe emitter lood. ΤR3is α ñ.π.Ñ. type tronsistor connectedos οη

emitfer follolverιy,ith TR2octing as its emitter lood. TR2base ond TR3base ore bothconnected to fhe driver stoge output

ü. Οη the negotive portionof the input signalTR3conducts ond TR2is cut-off .Οη the porh of the signal ι,,rhichore positive TR2conducΕand TR3is cut-off .

Resistor R4 and diode Dlprovldebose bias for the output tronsistors, preventingcrossoverdistortion.DiodeDlhos α temperature choracteristic similorto the emitter-bose iunctionof α transistor, ond tends to compensote for resistance voriotionwith temperoture of TR2and TR3.

7, The octuoloutput ]ood is the loudspeakerιyhichis connected, νßα copocitorC4, το τhe emiττers TR2ολd TR3,and therefore posses current οη both holf

cyclesof the input signol.

ΙιΛΑ.909


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8. D.C.negative feedbock,whichstobilizesthe ιvorking voltageof the outputtransistor, is provided by resistor R§, connected between the commoι]emitter

iunctionof TR2ond TR3ond the bose of TRl. ResistorRllimihthe minimumvolue of sourceimpedonce.TESΤΙNGANDFAULΤLOCAΤΙON9. Το goin occes for testing or foult locotion remove the four scre\^/s ι̂ ιhßòh ore

locoted ßη the corners of the bock ponel. Ensure that the gasket is not dornoged,,yhen removing theponel.

Ιο. The omplifiercomponentboord is mounted οη pil|ors vvithinthe unit ond removalis self-evident.

Ιl. The followingtesf figures shouldbeobtgined vvithο serviceobleunit:

(q) SupplyVolmge- Ι8 volts(b) CurrentConsumptionι^ιßh ηο input signal - betιyeen ü ond Ι0 mA.(c) Currentconsumption οt fulloutput (500 mW) should be bet,,veen 59ond

ü5 mA.

ΝΟΤΕιThe omplifieris not connected to eorth.

'νlΑ.909


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Cct.Ref. Value Description

COMPONENTSLΙST

- Τοl. RocalKat' ο/ο ÑοττΝο.

RιR2R3R4R5

Resistors

Capocitors

òιc2

c3

c4

330Ω390Ωι .5κΩüα)5. üκΩ

*νγ ι0*νγ ι0*νγ ι0*νγ ι0*νγ ι0

35ν 2025ον ß13

ι üν ßß3

9ι 99039Ι99ο49ι 99089|98979199Ι4

9Ι4ν6

9ι üι 87

92Ι5¸

909γ279106829Ι 0ü8ι

906720

AD.700380AD.700487

9ιü258

Transistors

τRιτR2TR3

Diodes

Dι

Miscellaneous

CompositionCompositionCompositionCompositionComposition

Tanto lum

Ceramicon

Electrolytic

Ν. Ñ. Ν. SiliconΝ. Ñ.Ν. SiIiconÑ. Ν. Ñ. Silicon

Silicon

Czasket, loudspeakerGasket, back panel

Loudφeaker(35Ω)

4.7yF

.0Ι µF

Not Used

Ι ωµt

LSι

ΜΑ.909


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COMPONENΤSLΙST

Cct.Ref. Volue Description

- Τοl. RacalKat' ο/ο Parτ Νο.

Resistors

RιR2R3R4R5

Capacitors

Cl 4.7yFC2 ,0ΙµFC3 Not UsedC4 Ι ΦµF

Trons istors

ΤRιTR2TR3

Diodes

Dι,

Miscellaneous

CompositionCompositionCompositionCompositionComposition

Tontalum

Ceromicon

Electrolytic

Ν.Ñ.Ν.SiliconΝ.Ñ.Ν.SiliconÑ. Ν.Ñ. Silicon

SiIicon

Gasket, loudspeokerGasket, back ponel

Loudspeaker(35Ω)

330Ω390Ωι .5κΩü8ò)5. üκΩ

*νγ ι0*νγ ι0*γγ ι0ßνγ ι0*νγ ι0

9ι 99039199049ι 99089|9897919914

914Φ6

91ü187

921529

909φ79ι 0ü829ι 0ü8ι

9α6720

AD.700380AD.700487

9ιü258

35ν 20250ν ]13

ιüν :ß3

LSι

ΜΑ.909


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PLiΑ.7

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Fig. 1


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Fig.2

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ΜΑ.θ09LoudspeakerAmpiifier

Racal Loudspeaker Amplifier MA.909

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