RL-903 Receiver
Glenayre Document Number: 9110.00148
MAINTENANCE
Issue 1, Rev. C: 12/10/96
8.
Repeat sensitivity check at 3 MHz below carrier frequency. Set synthesizer and signal
generator back to carrier frequency when done. Be sure to have front-end adjustment
performed by factory personnel as soon as possible.
9.
Refer to Figure 7-5. On IF board, adjust Ll, L3, L5, L7, and L8 for maximum sensi-
tivity. Repeat this step until no further improvement is noted.
10. (narrowband receiver only) Adjust C51 for maximum sensitivity.
11. Place audio analyzer probe at ac_audio line, J1-1 (TB2-1).
12. Adjust L5 for minimum distortion with 100-Hz audio signal.
13. Set signal generator level to -47 dBm and restore audio frequency to 1000 Hz. Distor-
tion may be minimized by slightly detuning L1, L3, and L7 for minimum distortion,
as observed on distortion analyzer. Use audio oscillator and distortion analyzer to
measure distortion at 1000 Hz and adjust for best overall distortion. Do not detune
components more than 1/4 turn.
14. Adjust second l.o. at C52 for minimum distortion. If using internal reference oscilla-
tor, adjust trim cap on U6 for minimum distortion. Do not detune more than 1/4 turn.
15. Restore jumpers and controls to normal positions.
7.6
Squelch and RSSI Adjustment (IF board unless noted)
The following procedure sets TIGHT squelch for normal operation.
TIGHT Squelch Adjustment Procedure
1.
Set signal generator level for the desired signal quality (typically 30 dB SINAD, ap-
proximately -100 dBm).
2.
Set front-panel SQUELCH switch to TIGHT to enable carrier squelch.
3.
Set front-panel TIGHT squelch control so that signal is barely squelched. (If signal
cannot be squelched, leave control completely cw. This is highly unlikely.) Front-
panel SQUELCH LED should go on and off, depending on squelch status.
The following procedure sets NORMAL squelch. Perform the procedure after completing
the TIGHT squelch procedure.
NORMAL Squelch Adjustment Procedure
1.
Set signal generator level for desired signal quality (typically 12 dB SINAD, approxi-
mately -116 dBm).
2.
Set front-panel SQUELCH switch to NORMAL to enable noise squelch.
3.
Adjust front-panel NORMAL SQUELCH control to barely squelch receiver. Verify
level. UNSQUELCH LED4 should go on and off, depending on squelch status.
4.
Set front-panel SQUELCH switch to TIGHT.
Page: 7-6
Copyright © 1996 Glenayre
Print Date: 12/05/96