EVALUATE OPERATION OF AN/GRC-193A RADIO SET
Upon completion of this lesson, you will be able to verify the proper operation of
an AN/GRC-193A radio set.
This subcourse is based on TM 11-5820-924-13 and other material approved for US
However, development and progress render the text continually
subject to change. Therefore, base your examination answers on material presented
in this lesson rather than on individual or unit experience.
As an organizational maintenance person, you must be able to
perform an operational check on all radios for which you are responsible to
classify malfunction or determine operability of the set. You may be told to check
a radio set as a routine check, or it could be because of an operator-reported
problem. To aid you in this, the AN/GRC-193A has indicators built into the set to
tell you about equipment condition. You must know the meaning of these indicators.
For any operational check, you must verify proper installation; that is, all
cabling is correct, items are correctly mounted and clamped in place, and proper
connections are made for the mode of use. (See the safety summary in Lesson 1.)
8. CONTROLS, INDICATORS, AND CONNECTIONS.
Tables 1 through 4 list controls,
indicators, and connections for the four major components.
To do an operational
check in voice mode, the test frequency must be set on the RT-1209 (must be above 2
MHz). The SB switch should be set to USB. The VOLUME control should be set to the
OFF position. The MODE switch is set to V-TR. On AM-6879, the TTY ON/OFF/SPKR ON
switch should be set to OFF. The SQUELCH control should be OFF. On AM-6545, CB1
and CB2 must be pushed in (the buttons, protected by a plastic boot, pop out on
overload and must be reset). Make certain that the correct antenna, as determined
by frequency, direction, time of day, distance, etc., is connected to CU-2064. If
the site you must contact is on the other side of the mountain, use near-vertical
incidence sky wave(NVIS). Turn the VOLUME control switch to a midrange position.
Press the FAN/LAMP TEST button on the face of AM-6545, see that the six LEDs across
the face of the AM-6545 light, and listen for the fans to run. Allow the system to
warm up for about 90 seconds. The amber TUN lamp comes on in the AM-6545, and a
beeping 1-kHz tone is heard in the handset during warm-up. When the set has warmed
to operational condition, the green RDY lamp lights and the beeping tone stops.
Listen to the test station, turn the SPEAKER switch on, adjust the VOLUME OFF/MAX
for a comfortable listening level, and then adjust the SQUELCH control on AM-6879.
Momentarily depress the PTT switch on the handset. The green XMT lamp and yellow
TUN lamp will light, and a 1-kHz tone will be heard for less than 20 seconds. When
the green RDY lamp lights, tuning is complete.
Contact your test station, and
ensure two-way communications.
Change the SB switch to LSB, and ensure two-way
communications. Sidetone will be heard in the transmit position, and the M1 meter
deflects to the right when you whistle or talk into the microphone.
should be silenced in the transmit position.
If the yellow FIL lamp lights, it
indicates low RF power out and requires that the AM-6545 be