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Bendix/King
KMA28
Audio Amplifier/Intercom/Marker Beacon Receiver
006-10565-0000
3-2 Rev. 0, Sept. 00
3.1.3 Public Address (PA) Function
The KMA 28 has a public address capability when an optional external PA switch is in-
stalled. When this switch is put into the PA position, the pilot’s microphone is placed on
a speaker output. The copilot can continue to use the selected Com radio.
When this PA function is installed a separate cabin speaker (rather than the cockpit
speaker) is usually utilized to prevent feedback.
3.2 Power Switch /Emergency (EMG) Operation
Unit power is turned on and off by pushing the volume knob. In the OFF or
"EMERGENCY" position, the pilot is connected directly to Com 1. This allows communi-
cation capability regardless of unit condition. Any time power is removed or turned OFF,
the audio selector will be placed in the emergency mode.
The power switch also controls the audio selector panel functions, intercom, and marker
beacon receiver. Unless the mic selector is in Com 3 mode, at least one of the selected
audio LEDs will be on (Com 1 or Com 2).
3.3 Microphone Selector
When the mic selector switch is in the Com 1 position, both pilot and copilot will be con-
nected to the Com l transceiver. Only the person who presses their Push To Talk (PTT),
will be heard over the aircraft radio. Turning the rotary switch to the COM 2 position will
place pilot and copilot on Com 2.
The KMA28 gives priority to the pilot’s PTT. If the copilot it transmitting, and the pilot
presses his PTT, the pilot’s microphone will be heard over the selected com transmitter.
Turning the mic selector fully counterclockwise places the pilot and copilot on Com 3.
Com 3 receive audio is automatically placed in the headset (and speaker if selected). Com
1 and/or Com 2 receiver audio can be selected to monitor those transceivers.
The KMA28 has an automatic selector mode. Audio from the selected transceiver is
automatically heard in the headsets and speaker. You can check this function by switch-
ing from C
OM 1 to COM 2 and watch the selected audio light on the selector change from
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 in the KMA28 audio selector will blink
as a further indication of the selected transmitter.
When switching the mic selector rotary switch from C
OM 1 to COM 2, while COM 2 audio
had been selected, Com 1 audio will continue to be heard. This eliminates the pilot hav-
ing to switch Com 1 audio back on, if desired.
When switching from C
OM 1 to COM 2 while Com 2 has NOT been selected, Com 1
audio will be switched off. In essence, switching the mic selector will not effect the se-
lection of Com audio.