Cessna 1980 172RG Cutlass Pilot Operating Handbook page 131

.3
CESSNA 300 NAV/COM
(TYPE RT-385A)
17.
NAV/TO-FROM INDICATOR - Operates only with a VOR or localizer signal.
Red NAV position (Flag) indicates unusable signal. With usable VOR signal,
indicates whether selected course is TO or FROM station. With usable localizer
signal, shows TO.
18. RECIPROCAL COURSE INDEX - Indicates reciprocal of selected VOR course.
19.
OMNI BEARING SELECTOR (OBS) - Rotates course card to select desired
course.
20.
AUTOMATIC RADIAL CENTERING (ARC-PUSH-TO/PULL-FR) SELECTOR -
In center detent, functions as conventional OBS. Pushed to inner (Momentary On)
position, turns OBS course card to center course deviation pointer with a TO flag,
then returns to conventional OBS selection. Pulled to outer detent, continuously
drives OBS course card to indicate bearing from VOR station, keeping course
deviation pointer centered, with a FROM flag. ARC function will not operate on
localizer frequencies.
21. AUTOMATIC RADIAL CENTERING (ARC) LAMP - Amber light illuminates
when Automatic Radial Centering is in use. Light dimming is only available
when installed with an audio control panel incorporating the annunciator lights
DAY/NITE selector switch.
22.
COURSE CARD - Indicates selected VOR course under course index.
Figure 1. Cessna 300 Nav/Com (Type RT-385A), Operating Controls
and Indicators (Sheet 2 of 3)
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PILOT'S OPERATING HANDBOOK
SUPPLEMENT
1 July 1979
PILOT'S OPERATING HANDBOOK
SUPPLEMENT
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 rechecked
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 July 1979
.3
CESSNA 300 NAV/COM
(TYPE RT-385A)
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