RECEIVER AUDIO DISTORTION TEST. - TM-11-5820-401-34-30104

T M 11-5820-401-34-3/0967-LP-432-3060

3-6. RECEIVER AUDIO POWER TEST. (CONT)

TEST PROCEDURE

Muted Audio Power Test

1. Connect ME-30(*)/U INPUT lead A to MK-1978/VRC SPKR jack; connect lead B to GND

jack. (See test setup diagram

2. Adjust AN/URM-103 RF TUNING control for 60.00-MHz display on AN/USM-207.

NOTE

To produce a display on the AN/USM-207, the AN/URM-103 rf level must be increased

by turning the LO RF UV control clockwise. When the display appears, readjust the

AN/URM-103 RF TUNING control until the AN/USM-207 indicates 60.00 MHz, and reset

the LO RF UV control to 20 v.

3. Disconnect T-connector from AN/USM-207.

4. Turn R-442/VRC VOLUME control fully clockwise.

STANDARD. ME-30(*)/U meter should indicate at least 17 volts.

5. If ME-30(*)/U meter indication is less than 17 volts, see troubleshooting chart 3-10.

Unmuted Audio Power Test

6. Change MK-1978/VRC AUDIO switch to UNMUTED setting.

7. Step ME-30(*)/U RANGE selector switch to lower settings until reaching most exact

on-scale reading.

STANDARD. ME-30(*)/U meter should indicate at least 7.75 volts.

8. If ME-30(*)/U meter reading is less than 7.75 volts, see troubleshooting chart 3-10.

Fixed Audio Power Test

9. Connect ME-30(*)/U INPUT lead A to MK-1978/VRC INTERCOM jack.

10. Set ME-30(*)/U RANGE selector switch to lower settings until reaching most exact

on-scale reading.

STANDARD. ME-30(*)/U meter should indicate at least 0.16 volts.

11. If ME-30(*)/U meter indicates less than 0.16 volts, see troubleshooting chart 3-10.

RECEIVER AUDIO DISTORTION TEST.

3-7.

PURPOSE. This test checks the ability of the R-442/VRC to minimize distortion. It is similar to the

Receiver Sensitivity Test (paragraph 3-3), except that now a strong (20-v) rf level is used instead of

a weak (0.5-v) one. The 20-v rf level is injected into the R-442/VRC ANTENNA port. The audio

distortion, measured at the MUTED AUDIO output jack of the MK-1978/VRC, should be less than 8

percent.

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