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2.4.14.1.1 Entertainment muting
The KMA 28B-system incorporates a "Soft Mute" system. This will mute the entertainment devices dur-
ing 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.
Caution: Local oscillators and internal signals from entertainment equipment can cause undesired inter-
ference with other aircraft systems. Before takeoff, operate the entertainment 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 devices.
All additional entertainment devices must be switched off for both takeoff and landing.
2.4.14.1.2 Entertainment 2 Mute (Pin V)
The ICS button on the KMA 28B controls the muting ("Karaoke mode") of entertainment source #1.
Connecting J2 pin V to ground through a SPST switch places the entertainment #2 music source into the
Karaoke 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 lesser importance.
See section 2.4.14 for alternative connection.
2.4.15 KMA 28B Intercom expansion (J2, Pins P, S, and C)
The KMA 28B contains a 6-place intercom. In applications where more intercom positions are needed,
Honeywell can provide intercom expansion units, such as the IntelliPax, part number 11606, 11606R, etc.
These can add up to six additional stereo intercom stations, plus independent music input. Interface to the
expansion unit is through J2, pins P (audio input from expansion unit), S (audio output to expansion unit),
and C (9 VDC expansion power).
2.5
Marker Beacon Installation
The marker beacon receiver is an option included in the KMA 28B. Non-marker (PMA7000) units can
provide audio interface with the external receiver (see section 2.5.4).
2.5.1
Marker Antenna Installation
A marker beacon antenna, appropriate to the type and speed of the aircraft, is required (not included).
Refer to aircraft and antenna manufacturer's installation instructions, as well as AC43.13-2A (or later
revision), Chapter 3, for information on proper antenna installation techniques. The marker beacon an-
tenna must be mounted on the bottom of the aircraft.
2.5.2
External Marker Lights (Marker version)
For installations that require external marker beacon lights, there are three outputs that can drive 12-Volt
lamps only. The external output lamps are driven high (typically +9 VDC 1.5 VDC unloaded, at MAX
brightness) when active. Maximum source current per lamp is 125 mA. Voltage varies with photocell
dimming.
2.5.3
Middle Marker Sense (Marker version)
A Middle Marker Sense output signal is available from the 7000B to flight control systems. This function
will not operate during the test mode. This output will go to +4.5 VDC ( 1.0 VDC) when a valid Middle
Marker signal is received. This output is J1, pin 2.
D201106000060
Bendix/King
KMA 28B Audio Selector Panel and Intercom System
Installation and Operator's Manual
Page 2-7
June 2011
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