RECEIVER AUDIO POWER TEST. - TM-11-5820-401-34-30379

TM 11-5820-401-.34.3/0967-LP-432-3060

5-5. OLD SQUELCH TEST .(CONT)

OLD SQUELCH Test at 75.00 MHz

25. Change R-442/VRC MC-TUNE-KC switch to 75.00 MHz.

26. Turn AN/URM-103 RF TUNING control for 75.00-MHz meter indication.

27. Adjust AN/URM-103 RF TUNING control for 75.00-MHz display on AN/USM-207. To produce

display, see note under step 1 and readjust RF TUNING control until AN/USM-207 indicates

75.00 MHz.

28. Repeat steps 2 through 8.

5-6. RECEIVER AUDIO POWER TEST.

PURPOSE. This test checks the ability of the R.442/VRC to drive its three audio outputs, namely:

1. The MUTED audio output, which supplies power to the speaker.

2. The UNMUTED audio output, which supplies power to the headphones.

3. The FIXED LEVEL audio output, which supplies power to the interphone system.

An rf level strong enough to drive the A4200 module into limiting (20 v) is injected into the R-442/VRC

ANTENNA port. Audio output voltages are then measured at Test Cable No. 1 terminals F, S, and K to

make sure minimum standards are met.

TEST EQUIPMENT AND MATERIALS

Matching Unit CN-901/U

Power Supply PP-1104(*)/G

Ac Voltmeter ME-30(*)/U

Resistor, 600-ohm 5%, 2-watt

Frequency Counter AN/USM-207

Resistor, 150-ohm 5%, 2-watt

Signal Generator AN/URM-103

Rf Cables (two) RG-58/U

Test Cable No, 1

Adapter (T-Connector) UG-274 B/U

NOTE

The 600- and 150-ohm resistors provide impedance matching loads for the audio

transformer. The 600-ohm resistor is used in place of Loudspeaker LS-454/U, which

would issue a loud, distracting tone when the R-442/VRC VOLUME control is adjusted

during the test. If no 600-ohm resistor is available, however, the loudspeaker must be

connected.

5-15