Signal Paths of Simulator, Set, Radio

C2, TM 11-6625-564-45

the potentials.

The meter indicates the

d. A frequency readout mechanism is lo-

following:

cated in the radio set simulator which indi-

cates, through windows on the front panel of

( 1 ) Output level of the + 27.5-volt direct-

the radio set simulator, the exact frequency

current (dc) power source.

selected by the radio set control. The radio set

(2) Automatic direction finder (adf) con-

control cable is connected to jack J1 of the

trol circuit potential and continuity.

radio set simulator.

(3) Antenna and radiofrequency (rf) cir-

e. Six lamps on the front panel of the radio

cuit potential and continuity.

set simulator indicate continuity of their re-

(4) Shield ground circuit continuity.

spective' functions. Following is a listing of

(5) Sensitivity control circuit potential

the lamps and their functions:

and continuity.

(6) A u x i l i a r y a u d i o c i r c u i t p o t e n t i a l a n d

continuity.

(1) The SQ. DIS lamp lights when the

b. The radio set simulator contains power

receiver-transmitter squelch circuit is

converter module 1A3 that supplies +175-volt

disabled by. the radio set control

dc plate voltage to the ultrahigh frequency

squelch control. This condition indi-

(uhf) test generator (does not apply to the

cates that the path from the +27.5-

MK-731A/ARC-51X) and +225 volts dc to

volt dc supply through the SQ. DIS

the adf system in the aircraft (if so equip-

lamp, through the radio set control

ped). With the TEST SELECT switch in the

ADF position, the meter is connected to the

cable, through the radio set control

adf relay circuit to indicate the operating

squelch

control,

ground

condition of the adf equipment.

When the

continuous

PTT switch is depressed, relay K1 is ener-

(2) The XMIT LOAD lamp lights when

gized, and +175 volts dc from the power con-

the XMIT LOAD switch is de-

verter is supplied to the uhf generator plate

pressed. This condition indicates that

circuit (does not apply to MK-731A/ARC-

the +27.5-volt dc power supply oper-

51X).

In MK-731A/ARC-51X only, when the

ates under loaded conditions.

PTT switch is depressed, relay K1 is ener-

(3) The T/R lamp lights when the radio

gized, and +27.5 volts dc from the transient

set control function select switch is set

blanker is supplied to the uhf generator

to T/R. This condition indicates that

circuit.

The XMIT lamp lights to indicate

the path from the +27.5-volt dc,sup-

the transmit function.

ply through the T/R lamp and the

c. A uhf test generator module is lo-

radio set control cable to the T/R

cated in the radio set simuiator. W i t h t h e

position of the function select switch

TEST SELECT switch in either VSWR CAL

is continuous.

or VSWR TEST, this module generates a 300-

(4) The T/R+G lamp lights when the

megacycle (mc) signal that is applied through

radio set control function select

a directional coupler to the antenna or dummy

switch is set to T/R + G. This condi-

load when the PTT switch is depressed.

tion indicates that the path from the

W ith the TEST SELECT switch in the VSWR

+27.5-volt- dc supply through the

CAL position, the meter is connected to the

T/R + G lamp, relay K1, and the ra-

forward output circuit of the directional cou-

dio set control cable to the T/R+G

pler. The VSWR CAL. control varies the out-

position of the function select switch

put of the uhf test generator until the meter

is continuous.

indicates CAL on the B scale. With the TEST

(5) T h e X M I T l a m p l i g h t s w h e n t h e

SELECT switch in the VSWR TEST position,

PTT switch is depressed. This con-

the meter is connected to the reflected output

dition indicates that the radio set

circuit of the directional coupler for a stand-

simulator is generating a 300-mc test

ing wave ratio (swr) indication.

signal.