Microphone Amplifier Assembly A80, Circuit Functioning

11-5820-401-35-1/NAVELEX

0967-432-3020

minal T of W701J702, through W701S702, to

microphone output of the audio accessory has

erminal S of W701S701. An operator can listen

been amplified in microphone amplifier A80 (para

to either of the channels being used for retrans-

33), it is applied through switch W701S701 and

mission but cannot key either transmitter. How-

terminal U of connector W701J701 to the trans-

ever, he can modulate the keyed transmitter de-

mitting circuits of the receiver-transmitter.

pending on the position of RAD TRANS switch

(2) When RAD TRANS switch W701S701

W701S701. Similarly, when the C-2299/VRC is

is at position 2, muted audio from the second re-

connected to the AM-1780/VRC (fig. 3-1), crew-

ceiver-transmitter is fed from terminal J of

members cannot key the recei ver-transmitters be-

W701J702 through the same circuit as given in

cause the INSTALLATION switch on the AM-

(1) above. The audio accessory will control the

1780/VRC is set to RETRANS position which

second receiver-transmitter connected to W701-

opens the keying control lines.

J702 through the same circuits described in (1)

above.

3-3. Microphone Amplifier Assembly A80,

b. When RETRANS switch W701S702 is in

Circuit Functioning

ON position, the monitor amplifier output of the

(fig. 3-4)

first receiver-transmitter is fed to the microphone

Microphone amplifier assembly A80 is a three-

line of the second receiver-transmitter from ter-

stage, direct-coupled amplifier used in the C-

minal K of W701J701 and terminal U of con-

2299/VRC (fig. 32) and also in control boxes of

nector W701J702. Similarly, the monitor ampli-

Intercommunication Set AN/VIC-l (V) (TM 11-

fier output of the second receiver-transmitter is

583034012): C-2296/VRC, C-2297/VRC, and

fed to the microphone line of the first receiver-

C-2298/VRC. The A80 receives its input signal

transmitter from terminal K of W701J702 to ter-

from the dynamic microphone connected to the

minal U of W701J701. When a keying signal is

control box. Its output is fed to the speech ampli-

received (by operation of squelch and retransmit

fier of the receiver-transmitters or to the inter-

relays) by the first receiver-transmitter, the sec-

phone amplifier of the AM-1780/VRC.

ond receiver-transmitter will be keyed through a

a. The input from the dynamic microphone is

circuit from terminal T of W701J701 through

fed through an RF filter network composed of

W701S702, to terminals S of W701J702. Sim-

capacitors C81 and C82 and inductor L81;

ilarly, when a keying signal is received by the

through impedance-matching resistor R81 and

second receiver-transmitter, the first receiver-

coupling capacitor C83 to the base of transistor

transmitter is keyed through a circuit from ter-

Figure 3-4. Microphone amplifier assembly A 80, schematic diagram.

3-5