Simulator, Set, Radio

C2, TM 11-6625-564-45

+ receiver circuitry; when the switch is set to

eter R2 and applied to the antenna through

the ADF position, +27.5 volts dc is applied

directional coupler DC1.

Directional coup-

to the adf relay in the receiver-transmitter.

ler DC1 provides two points for testing

When XMIT LOAD switch S4 is set to ON,

forward and reflected voltages to and from

the antenna.

+27.5 volts dc is applied through thermostat

The TEST SELECT switch

(S1) connects forward voltage to meter Ml,

S5. XMIT LOAD lamp DS4 will light if the

when set to VSWR CAL, and reflected volt-

aircraft +27.5-volt dc source is regulated cor-

age to meter Ml when set to VSWR TEST.

rectly. When the TEST SELECT switch is set

c.1. Uhf Test

Generator Module 1A5

to +27.5V, meter Ml is connected to the air-

(MK-731A/ARC-51X Only). The 27.5 volts

craft +27.5-volt dc source. The meter will

dc applied to module

1A5 is also

show a normal indication (green sector) on

supplied to relay K1. When relay K1 is en-

scale A if the voltage is correct. When PTT

ergized by depressing PTT switch S2, and

switch S2 is depressed and switch S1 is in

TEST SELECT switch S1 is in the VSWR

the VSWR CAL or VSWR TEST position, re-

CAL or VSWR TEST position, the +27.5

lay K1 is energized and B+ is applied to uhf

volts dc is applied to VSWR CAL potentiom-

test generator module 1A5.

This action

eter R2. The 300-mc output of uhf test gen-

places the radio set simulator in transmit

erator module 1A5 is controlled and varied

function, and XMIT lamp DS3 will light.

by VSWR CAL potentiometer R2 and applied

When the squelch disabling switch of the

to the antenna through directional coupler

radio set control is activated, the SG DIS

DC1.

Directional coupler DC1 provides

lamp DS6 will light.

test points for testing forward and reflected

Caution: Although the XMIT LOAD switch

voltages to and from the antenna. The TEST

when set to ON activates the transmit func-

SELECT switch connects forward voltages

tion, do not practice this method of operation.

to meter Ml, when set in VSWR CAL, and

reflected voltage to meter Ml when set in

b. Transient Blanker Module 1A4 and

VSWR TEST.

Power Converter Module 1A3. The + 27.5

d. ADF Supply Circuit. The +225 volts dc

volts dc applied to transient blanker module

generated by power converter module 1A3 is

1A4 is converted into three regulated out-

applied through relay K1 (in the deenergized

puts that include one regulated +18.9-volt dc

state) to the plate circuits in the adf equipment

filament supply, one regulated +27.5-volt dc

in the aircraft (if so equipped). When the

supply, and one regulated +20-volt dc sup-

TEST SELECT switch is set to +225V, meter

ply. The +27.5 volts dc is applied to power

Ml is connected to the +226-volt dc adf sup-

converter module 1A3 which changes the dc

ply circuit to indicate continuity and po-

to alternating current (ac), steps up the volt-

tential of the circuit to the adf equipment.

age, converts the ac voltage back to dc, and

e. Audio Amplifier Modules 1A1 and 1A2.

supplies three outputs (+175 volts, 80 milli-

The output from the pilot's headset micro-

amperes (ma) dc; +225 volts, 15 ma dc; and

phone is applied to the input of audio ampli-

an 9.65-volt ac auxiliary audio signal). The

fier No. 2 module 1A2. The signal is ampli-

auxiliary audio signal is adjusted by poten-

fied and applied to HEADSET H-101A/U

tiometer R17.

jack where the test headset receives the signal.

c. Uhf Test Generator Module 1A5 (MK-

The volume is varied by AUDIO GAIN po-

731/ARC-51X Only). The +175 volts dc gen-

tentiometer R23. The output of the test head-

erated by power converter module 1A3 is

set microphone is applied to the input of au-

applied to relay K1. When relay K1 is ener-

dio amplifier No. 1 module 1A1. This sig-

gized by depressing PTT switch S2, the +175

nal is amplified and applied to the pilot's head-

volts dc is applied to VSWR CAL. potentiom-

set. The volume is varied by the volume con-

eter R2 and the plate circuit of uhf test

generator module 1A5.

trol on the radio set control.

The 300-mc output

of uhf test generator module 1A5 is con-

f. CAR RELAY Switch S3. CAR RELAY

trolled and varied by VSWR CAL. potentiom-

switch S3 is used only when testing dual re-