IF DISCRIMINATOR A4200 ALINEMENT. - TM-11-5820-401-34-30188

TM 11-5820-401-34-3/0967-LP-432-3060

3-18. TUNER A1000 ALINEMENT. (CONT)

Mixer Adjustment

31.

Set R-442/VRC MC-TUNE-KC control to 52.00 MHz.

Adjust AN/URM-103 RF TUNING control to 52.00 MHz. Check on frequency counter.

32.

33.

Set AN/URM-103 LO RF UV control for zero-rf output.

34.

Note reading on ME-30(*)/U.

35.

While observing ME-30(*)/U, increase rf output level of AN/URM-103 by turning LO RF UV

control until ME-30(*)/U drops to one-half of step 34 reading.

36.

Set ME-30(*)/U to l-volt scale.

Adjust C1404 (16) for lowest possible ME-30(*)/U reading.

37.

NOTE

The ME-30(*)/U reading can also decrease if C1404 is turned in or out too far. The first

sharp decrease in the ME-30(*)/U reading will indicate the correct C1404 adjustment.

IF DISCRIMINATOR A4200 ALINEMENT.

3-19.

PURPOSE. This procedure enables the discriminator to provide maximum separation of the audio

signal from the rf carrier. Adjusting for zero vdc at TP4003 ensures that T4206 and T4207 are con-

ducting equally around the carrier frequency. Adjusting for maximum ac at TP4007 ensures that the

discriminator is tuned exactly to the 11.5-MHz center frequency.

TEST EQUIPMENT AND MATERIALS

Matching Unit CN-901/U

Signal Generator AN/URM-103

T-Connector UG-274/U

Frequency Counter AN/USM-207

Power Supply PP-1104(*)/G

Loudspeaker LS-454/U

Maintenance Kit MK-1978/VRC

Voltmeter ME-30(*)/U

Multimeter ME-26(*)/U

TEST SETUP. Connect the equipment as shown in test setup diagram

. Remove R-442/

VRC bottom cover. (See paragraph 2-7.)

INITIAL EQUIPMENT CONTROL SETTINGS. Set equipment controls as indicated in the following table.

If using alternate equipment, inject 20-v rf at 30 MHz, 1-kHz modulation, and 8-kHz deviation.

3-102