LOCAL OSCILLATOR A1500 ALTERNATE ALINEMENT PROCEDURE.

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

3-17. LOCAL OSCILLATOR A1500 ALTERNATE ALINEMENT PROCEDURE.

PURPOSE. This procedure permits alinement of the local oscillator without the use of a signal

generator. The frequency of the local oscillator is checked directly with a counter; therefore, the

presence of an audible audio tone is not important. Thus, alinement does not depend on the per-

formance of the A4000 or A5000 sections of the receiver. The CRS Test must be done prior to

performing this alinement.

TEST EQUIPMENT AND MATERIALS

Frequency Counter AN/USM-207

One extra SMC rf cable

Amphenol Adapters (two) M-39012/16

T-Connectors (two) UG-274/U

Multimeter ME-26(*)/U

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

INITIAL EQUIPMENT CONTROL SETTINGS. Change the final settings used in the CRS Test as

follows:

1. Set R-442/VRC MC-TUNE-KC control to 30.00 MHz.

2. Set AN/USM-207 SENSITIVITY switch as necessary to trigger frequency counter.

ALINEMENT PROCEDURE

1. Connect ME-26(*)/U positive lead to TP3001 (1) and negative lead to ground. (See test setup

diagram

NOTE

In the following adjustments, it may not be possible to achieve zero-frequency error and

zero-vdc indication on the ME-26(*)/U. Local oscillator tolerance with the CRS

connected is 3.5 kHz. The ME-26(*)/U should not exceed 0.5 vdc.

2. Adjust L1502(2) for 41.5-MHz reading on counter and zero vdc (midscale) on ME-26(*)/U.

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

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