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Com 3 Audio; Public Address Function - Honeywell BENDIX/KING KMA28 Installation And Operation Manual

Audio amplifier /intercom/marker beacon receiver
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Audio Amplifier/Intercom/Marker Beacon Receiver
in the entertainment devices into the system. The audio signal at the entertainment input
must be a minimum of 500 mV P-P per channel for optimum music performance.
All entertainment devices must be switched off for both takeoff and landing. Entertainment distribution
Entertainment source #1 provides music for the pilot and copilot positions, while enter-
tainment source #2 provides music for the four passenger positions. The KMA 28-system
incorporates a "Soft Mute" system. This will mute the entertainment devices during ICS
or radio conversation.
Any signal appearing in the unswitched audio inputs will always mute the entertainment
sources, even though the passengers may not hear the audio tone itself.
Entertainment inputs #1 and #2 can be paralleled so a single entertainment source can
serve both the passengers and the crew. It is suggested however, that a switch (DPDT) is
installed between the single entertainment device and entertainment input #1. This will
allow the pilot and copilot to decide if they hear entertainment while in the Crew mode.
Caution: Local oscillators and internal signals from some entertainment equipment can
cause undesired interference with other aircraft systems. Before takeoff, operate the en-
tertainment devices to determine if there is any adverse effect within the aircraft systems.
If any unusual operation is noted in flight, immediately switch off the entertainment de-
All entertainment devices must be switched off for both takeoff and landing. Entertainment 2 Mute (Pin V)
The ICS button on the KMA 28 controls the muting ("Karoake mode") of entertainment
source #1.
Connecting J2 pin V to ground through a SPST switch places the entertainment #2 music
source into the Karoake Mode. In this mode, incoming music and intercom conversation
will not mute the music for the passengers' intercom net. This allows uninterrupted music
during casual conversation and at times when radio communications are of lessor impor-

2.4.11 Com 3 Audio

As installed in the standard configuration, the KMA 28 Com 3 audio is heard while the
mic selector switch is in the Com 3 position (fully CCW). Pushing the receiver selector
buttons can monitor Com 1 and Com 2 audio. If monitoring of Com 3 is desired in Com 1
or Com 2 mic selector position, connect Com 3 audio in parallel to the AUX input (J1,
pin 11).

2.4.12 Public Address function

The KMA28 has a Public Address function. By connecting the top connector (J2), Pin 18
to ground, the pilot's microphone audio is placed on the cabin speaker output. When the
Page 2-5
Rev. 0, Sept. 2000


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