Principles of Operation

TM 11-5821-277-20

Emitter current of shunt re-

MOD 1 10 A FS.

resistor and modulator cir-

cuit. (Meter calibrated to

read 10 amperes full-

scale.)

DRIVER V 100 V FS. - - - - Driver/amplifer collector

voltage through a series

multiplying resistor.

(Meter calibrated to read

100 volts full-scale

Driver/amplifier collector

DRIVER 1 1 A FS.

and shunt resistor circuit

current. (Meter calibrated

to read 1 ampere full-

scale.)

Power amplifier and shunt

PA GRID 1 100 MA FS.

resistor ciruit grid cur-

rent (Meter calibrated to

read 100 milliamperes full-

scale.)

PA B+ 1000 V FS.

Transmitter power supply

and rester multiplier junc-

tion circuit 400-volt out-

put. (Meter calibrated to

read 1,000 volts full-scale.)

Power amplifier plate and

PA CATH 1 1 A FS.

screen grid, shunt resistor

and plate supply line cir-

cuit current. (Meter cali-

brated to read 1 ampere

full-scale.)

PWR OUT 100 W FS.

Transmitter power output.

(Meter calibrated to read

100 watts full-scale.)

MIKE jack . . . . . . . . . . . . . . . . . . ---------------------

When microphone is connected to MIKE jack, and micro-

phone push-to-talk switch is pressed, transceiver switch -

es to transmit mode of operation and transmits voice

signals from microphone.

PHONE jack ___________________ ------------------

When headset is connected to PHONE jack, capability is

provided to monitor audio output of transceiver.

transceiver), and then transmitted into space.

3-2. Principles of Operation

When installed in an aircraft the push-to-talk

a. General. NormaIIy, the radio set is operated

switch and the microphone are usually wired to

r e m o t e l y from the aircraft cockpit with the

an intercommunication set (C1611D/AIC, or

control unit. The transceiver provides two func-

equivalent).

The

C-1611D/AIC

amplifies

the

tional modes of option: transmit and re-

a u d i o signal before application to the trans-

ceive. These modes of operation are described in

ceiver, and provides internal switching capability

b and c below.

to select the desired transceiver for transmission.

b. Transmit. The radio set functions in the

transmit mode when operating power is applied

c. Receive. The transceiver operates in the re-

and as the push-to-talk switch is held depressed.

cive mode of operation whenever power is ap-

The push-to-talk switch is not a part of the

plied to the radio set and the push-to-talk switch

radio set and may be on the microphone, the con-

is not pressed; therefore, an amplitude-modula-

trol column, the handwheel, or the cockpit floor-

ted carrier received at the antenna of the fre-

boards. When the push-to-talk switch is held de-

q u e n c y to which the radio set is tuned is

pressed and the operator speaks into the micro-

demodulated and detected by the transceiver.

phone, the audio signals from the microphone

The detected audio signals are routed through

are routed through the C-1611D/AIC and am-

the C-1611D/AIC and amplified and applied to

plitude modulate RF carrier (generated by the

the selected headset for monitoring.

3-2