Frequency accuracy - SB-740-91-010226

SB 740-91-01

Step

Setting and Instructions

Normal Indication

(8) Check to see that AN/URM-103 Deviation

(cont.)

Meter still indicates 3 kHz. Adjust

deviation adjust control if necessary.

(9) Slowly advance AN/URM-103 control until

LO RF -V control set-

Call indicator lights. Note setting of

ting should be 0.5 pV

LO RF lV control.

or less.

(10) Slowly reduce inputs to 0.4 lV. Tone

(Call indicator re-

squelch should remain unbroken.

mains lighted.)

(11) Repeat for frequency of 64.05 MHz and by

adjusting the AN/URM-103 controls as

follows:

(a) Band Switch. D

(b) RF Tuning. 64.05 MHz

Deviation Meter still indicates

3 kHz. Adjust deviation adjust

control if necessary.

(d) Slowly advance AN/URM-103 control

LO RF lV control

until Call indicator lights. Note

setting should be

setting of LO RF pV control.

0.5 lV or less.

Frequency accuracy

With an RT unit in transmit, see if receiver will pick up the RT unit's transmission. Frequencies used

should be 30.05, 52.95, 53.05, and 75.95 MHz. Verify tone quality and function of volume control during

this test. Volume con- trol should be checked for noisiness and flat or "dead" spots.

Audio output and distortion

(a) Connect the equipment in accordance with

figure B-5.

(b) Energize all the equipment and allow for a

5 minute warm-up before proceeding.

(1) Display Control. Set for desired dis-

play time.

(2) Sensitivity. 100 V

(3) Gate Time. (sec--):106

(4) Function. Freq

(d) On AN/URM-103, set the controls as follows:

(1) Band Switch. D

(2) RF Tuning. 60 MHz

(3) Deviation Range. 40 kHz

(4) Function. 1000 Hz

B-38