RECEIVER SELECTIVITY TEST. - TM-11-5820-401-34-30115

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

3-9. RECEIVER AUDIO RESPONSE TEST (X-MODE). (CONT)

Audio Response Test (X-Mode) at 5 kHz

26.

Turn AN/URM-127 FREQ RANGE DIAL to 50.

27.

Disconnect rf cable from Adapter UG-514. (See test setup diagram

28.

Connect rf cable to AN/USM-207 FREQ A connector.

29.

Adjust AN/URM-127 FREQ RANGE DIAL for 5-kHz display on AN/USM-207.

30.

Disconnect rf cable from ANUSM-207 FREQ A connector.

31.

Reconnect rf cable to Adapter UG-514.

STANDARD. ME-30(*)/U meter should indicate between + 2 db and -3 db of reading noted in

step 9.

32. if ME-30(*)/U meter does not indicate between + 2 db and -3 db of reading taken in step 9, see

troubleshooting chart 3-9.

Audio Response Test (X-Mode) at 10 kHz

33.

Turn FREQ RANGE DIAL to 100.

34.

Disconnect rf cable from Adapter UG-514. (See test setup diagram

35.

Connect rf cable to AN/USM-207 FREQ A connector.

36.

Adjust AN/URM-127 FREQ RANGE DIAL for 10-kHz display on AN/USM-207.

37.

Disconnect rf cable from AN/USM-207 FREQ A connector.

38.

Reconnect rf cable to Adapter UG-514.

STANDARD. ME-30(*)/U meter should indicate between + 2 db and -3 db of reading noted in

step 9.

39. If ME-30(*)/U meter does not indicate between + 2 db and -3 db of reading noted in step 9, see

troubleshooting chart 3-9.

NOTE

Before performing any other test in this section, see R-442/VRC X-MODE Setup

Procedure and do the following:

Set X-MODE-NORMAL switch S4001 to NORMAL.

Return Filter FL4002 to its original position.

3-10. RECEIVER SELECTIVITY TEST.

PURPOSE. This test checks the ability of the R-442/VRC A4000 tray IF Filters FL4001 and FL4002 to

reject unwanted signals and, thus, determine bandwidth. The R-442/VRC should have a minimum

bandwidth of 32 kHz at the filters' 6-db attenuation point and a maximum bandwidth of 80 kHz at their

60-db attenuation point. This is verified by:

1. Finding the minimum rf level which must be injected into the R-442/VRC ANTENNA port to

cause the CALL lamp to light.

2. Injecting twice the rf level found in step 1, while observing that the R-442/VRC CALL lamp is lit

when the frequency is offset 16 kHz from the carrier.

3. Injecting 1000 times the rf level found in step 1, while observing that the R-442/VRC CALL lamp

is off when the frequency is offset more than 40 kHz from the carrier.

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