Cessna 17273274 Pilot Operating Handbook page 155

SECTION 7
AIRPLANE & SYSTEMS DESCRIPTIONS
PHONE position (or vice versa) is not normally recom­
mended as it will cause audio from both communications
receivers (and any other navigation receiver with its audio
selector switch in the PHONE position) to be heard on both
the airplane speaker and the headset simultaneously.
AUTO AUDIO SELECTOR SWITCH
The audio control panel used with three transmitters incorporates a
three-position toggle switch, labeled AUTO, which is provided to automat­
ically match the audio of the appropriate NAV /COM receiver to the
selected transmitter. To utilize this automatic feature, leave all NA V / COM
audio selector switches in the center (OFF) position, and place the AUTO
selector switch in either the SPEAKER or PHONE position, as desired.
Once the AUTO selector switch is positioned, the pilot may then select any
transmitter and its associated NAV /COM receiver audio simultaneously
with the transmitter selector switch. If automatic audio selection is not
desired, the AUTO selector switch should be placed in the center (OFF)
position.
If the NAV / COM audio selector switch corresponding to
the selected transmitter is in the PHONE position with the
AUTO selector switch in the SPEAKER position, all audio
selector switches placed in the PHONE position will
automatically be connected to both the airplane speaker
and any headsets in use.
ANNUNCIATOR LIGHTS BRIGHTNESS AND TEST SWITCH
The audio control panel used with either one or two transmitters
incorporates a three-position toggle-type switch to contr.ol the brightness
level of the marker beacon indicator lights (and certain other annunciator
lights associated with avionics equipment). When the switch is placed in
the center (DAY) position, the indicator lights will show full bright. When
this switch is placed in the up (NITE) position, the lights are set to a
reduced level for typical night operations and can be further adjusted
using the RADIO LT dimming rheostat knob. The down (TEST) position
illuminates all lamps (except the ARC light in the NAV indicators) which
are controlled by the switch to the full bright level to verify lamp opera­
tion.
SIDETONE OPERATION
Cessna radios are equipped with sidetone capability (monitoring of
the operator's own voice transmission). While adjusting sidetone, be
7-38
NOTE
CESSNA
MODEL 172N
1 July 1979