COMTEK M-216 - Manual (Page 17)

Page 15
Possible Causes of Noisy Audio
1. Excessive Distances
Operating at a distances greater then 200 ft. may cause excessive noise.
2. Channel Selection
Operating on non-companded channels 1-40 will inherently have much
noisier characteristics. Companded channels 41-60 will produce the
best signal-to-noise performance.
3. Gain Problem
Check the microphone gain setting on the M-216 transmitter for normal
operation with the “voice” modulation indicator (See page 2 section d.)
Low modulation will render poor signal-to-noise ratio.
4. Channel Interference
Monitor the PR-216 receiver with the headphone plugged in and with
the transmitter turned “OFF” on the channel that the transmitter is
tuned to. Check the PR-216 receiver status indicator LED. If a steady
slow flash is indicated, the receiver is receiving a signal on the transmitter
channel and a new channel must be selected. If the status indicator LED
on the PR-216 receiver is illuminated continuously and noise is no
longer heard, then the channel is clear and channel interference is not
the problem.
5. Transmitter Power and Receiver Sensitivity
Check the M-216 transmitter for normal R.F. power and the PR-216
receiver for normal R.F. sensitivity. This can easily be done by range
checking the receiver and transmitter with the microphone cord antenna
removed from the transmitter. Turn on the transmitter and place it on a
non-metallic table. Turn on the receiver and plug in the headphone cord
into the receiver like it would normally be used. Then walk away from
the transmitter while listening for noise build-up just before the squelch
action takes place. A distance of 30-50 ft. should be obtained. Use
companded channels 41-60 for this test. If the receiver and transmitter
do not pass this test, both receiver and transmitter must be returned to
COMTEK for service.
M-216 TROUBLE SHOOTING (Continued)