Cessna 1980 182Q Pilot's Operating Handbook And Flight Manual page 269

PILOT'S OPERATING HANDBOOK
SUPPLEMENT
17
CESSNA 300 NAV/COM
(TYPE RT-385A)
The Cessna 300 Nav / Com incorporates a variable threshold automatic
squelch. With this squelch system, you set the threshold level for auto-
matic operation - the further clockwise the lower the threshold - or the
more sensitive the set. When the signal is above this level, it is heard even
if the noise is very close to the signal. Below this level, the squelch is fully
automatic so when the background noise is very low, very weak signals
(that are above the noise) are let through. For normal operation of the
squelch circuit, just turn the squelch clockwise until noise is heard - then
back off slightly until it is quiet, and you will have automatic squelch with
the lowest practical threshold. This adjustment should be re checked
periodically during each flight to assure optimum reception.
All controls for the Nav / Com, except the standard omni bearing
selector (OBS) knob or the optional automatic radial centering (ARC) knob
located on the course deviation indicator, are mounted on the front panel of
the receiver-transmitter. Operation and description of the audio control
panels used in conjunction with this radio are shown and described in
Section 7 of this handbook.
SECTION 2
LIMITATIONS
There is no change to the airplane limitations when this avionic
equipment is installed.
SECTION 3
EMERGENCY PROCEDURES
There is no change to the airplane emergency procedures when this
avionic equipment is installed. However, if the frequency readouts fail, the
radio will remain operational on the last frequency selected. The fre-
quency control should not be moved due to the difficulty of obtaining a
known frequency under this condition.
1 October 1979 5