Textron Cessna 172S Skyhawk SP, Information Manual

Page: 441 / 491

SECTION 9' SUPPLEMENTS
SUPPLEMENT 20 - FAA APPROVED
CESSNA
MODEL 172S'
3. RECEIVE AUDIO SELECT BUDONS.. Push button audio selection is
available for two Communications receivers ("COM 1", "COM 2"), two
Navigation receivers ("NAV I" and "NAV 2"), the internal Marker
Beacon receiver ("MKR"), one DME, one ADF, one additional auxiliary
receiver ("AUX") and a speaker amplifier ("SPR"). The 'AUX" position
could be used, for exam pie, 'for a second DME or ADF, When a
receiver's audio is selected, the green annunciator illuminates at the
side '01 the button. Push the button again to deselect the 'receiver's
audio. These buttons are "latched" type switches. 'When' oneal these
buttons is pressed, if will stay in Ihe "in" position until. the button Is
pressed again and it will be put in the "out" position and removes that
receiver from the audio. To provide additional feedback lor button
operation, activate the key "click" by pushing and holding both COM 1
and COM 2 receiver buttons for five seconds, and release. Repeat to
deleat the click.
4. MICROPHONE SELECTOR SWITCH (MIC) .- Used to select the
. desired transmitter lor the cockpit microphones. The "COM 1", "COM
2", and. "COM 3" positions are lor transmitting on the Com 1, Gam 2,
and
Com
3 'communications transceivers, respectively. When -the mic
selector switch is in the COM 1 position, both pilot and copilot will be
connected 10 the COM 1 transceiver. Only the person who presses
their Push-Io.Talk (PD) switch, will be heard over th,,. aircraft radio.
TUl]ling' the rotary switch to the COM 2 position will place pilot and
copilot 6n COM 2. The KMA 28 gives priority to the pilot's PD. " the
copilot is transmitting, and the pilaf presses his PD, the pilot's
microphone will be heard over the selected COM transmitter .. Turning
the mic selector countercloCkwise to COM 3 places:both the pilot and
copilot on COM 3. Com 3 receiver. audio is automatically placed in the
headset (and speaker if selected). COM 1 and/or COM.2 receiver
audio can be sefeCted to monitor those transceivers. Audio from the
selected transceiver is automaticaJly" heard in the headsets. This
function can be checked by switching Ir~m COM 1. to COM 2 and
watching the selected audio light on the selector change Irom COM 1
to COM 2.
This ensures the pilot will always hear the audio from the
transceiver he is transmitting on. When transmitting; the COM 1 or
. COM 2 LED audio selector will blink as a lurtherindication'of the
selected transmitter. When switching the mic selector switch from
COM 1 to COM 2, if the COM.1 audio has been selected; COM 1 audio
will continue to be heard .. When switching lrom COM 1 to COM 2 it
COM 1 has NOT been selected; COM 1 audio will be switched off., ,
Figure 1. Bendix/King KMA 28 Audio Selector Panel (Sheet 2 of 5)
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DeC
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