The receive audio signal from amplifier-modulator A2

TM 11-5820-509-35

output of this amplifier is divided between the +agc

relay K1 is energized, the 26.5-volt dc output at P1-7

circuit containing Q9, and the-agc circuit containing

also operates t/r relay K10l and screen voltage relay

CR12-CR13.

Agc amplifier Q9 is biased in the

K103 in the power amplifier compartment, and B + relay

nonlinear region of its operating characteristic and

K3, 500-kHz relay K4, and receiver antenna relay K5 in

functions as a common-emitter detector. The collector

the main chassis of the receiver-transmitter.

of Q9 is returned to ground through the bias network

associated with if. amplifiers Q2 and Q3 in amplifier-

d. The receive audio signal from amplifier-

modulator A2 and this permits a positive dc voltage to

modulator A2 is applied to driver Q10 in audio

be ap plied to these stages that is proportional to the

frequency amplifier A1 through receiver gain control

average level of receive audio signal. Audio filtering at

R54. This control is a screwdriver adjustment that sets

the output of Q9 is provided by capacitor C42. The

the maximum signal level available at the receiver

other part of the amplified output from Q8 is rectified by

audio output terminals.

Driver Q10 amplifies this

detector CRl2-CR13, filtered by capacitor C41, and is

incoming signal and routes it through transformer T3 to

then applied as a negative bias to the grid circuits of rf

push-pull audio output amplifier Q11-Q12. The resulting

amplifiers V 1 and V2 in signal data translator A3.

amplified audio signal is applied through transformer T5

Sidetone gate CR10 is enabled in the transmit mode by

and the VOLUME control to the connected audio output

sidetone bias rectifier CR101 in the power amplifier

device. A portion of the incoming receive audio s anal

compartment of the receiver transmitter.

When

is also applied to agc gate CR11 by automatic gain

engaged, the sidetone audio from output amplifier Q4 is

control R52. Agc gate CR11 is disabled during the

applied to driver Q10 through sidetone gain control R46

transmit period by a reserve bias of 26.5 volts dc that is

and receiver gain control R54. After the maximum

applied to it from vox relay K1. While disabled, no Agc

output level of audio output amplifier Q11-Q12 has been

voltages are available for if. amplifiers Q2 and Q3 of

established by the setting of R54, the sidetone output

amplifier-modulator A2 or to rf amplifiers V1 and V2 in

available during transmit periods is set by the

signal data translator A3. As a result, these stages

screwdriver adjustment of R46. In the receive mode,

operate at full circuit gain, using fixed bias during

sidetone gate CR10 is disabled and no output from the

transmit periods. In the receive mode, Agc gate CR11

microphone circuit is contributed to the driver output.

is enabled, however, and the audio signal from Agc gain

control R52 i. applied to agc amplifier OR The

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