LOC DDM PERFORMANCE TEST.

TM 11-6625-2975-40

TEST EQUIPMENT REQUIRED: Decade Resistor, Windslow 338

Differential Voltmeter, Fluke 887AB/AN

RF Cables, RG-58/U with BNC plug-to-double banana plug termina.

tions and RG-58/U with double banana plug terminations

EQUIPMENT SETUP: Connect test set to 115 vac power source.

Connect differential voltmeter to test set as Indicated In the following diagram.

EL9LY017

Turn on test equipment. Allow at least 30 minutes for warmup.

PROCEDURE

Enter frequency 108.10 MHz into test set.

Extinguish 150 Hz TONE SELECT key and record 90-Hz differential voltmeter Indication.

Extinguish 90 Hz TONE SELECT key and press (to light) 150 Hz TONE SELECT key.

Record 150-Hz differential voltmeter indication.

Divide value recorded in step 4 by value recorded In step 2. Resulting voltage ratio should be

between 0.99950 and 1.00050. If not, go to troubleshooting chart 2-1, sh 9.

Disconnect differential voltmeter from test set COMP connector and connect to DEMOD

connector.

Extinguish 150 Hz TONE SELECT key and press (to light) 90 HzTONE SELECT key.

Record differential voltmeter indication.

Extinguish 90 Hz TONE SELECT key and press (to light) 150 Hz TONE SELECT key.

Record differential voltmeter indication,

10.

Divide the value recorded in step 10 by value recorded in step 8. Resulting voltage ratio should

11.

be between 0.99950 and 1.00050. If not, go to troubleshooting chart 2-1, sh 9.

Disconnect differential voltmeter from test DEMOD connector.

12.

13.

Connect equipment as indicated in the following diagram.