Honeywell BENDIX/KING KMA28 User manual

Installation and Operation Manual
BENDIX/KING
BENDIX/KINGBENDIX/KING
BENDIX/KING
®
KMA 28
FAA-Approved TSO C50c, C35d
JAA-Approved JTSO-2C35d, C50c
Audio Amplifier /Intercom/
Marker Beacon Receiver
Document P/N 006-10565-0000
REVISION 0, SEPTEMBER 2000
WARNING
Prior to export of this document, review for export license requirement is needed.
Honeywell International, Inc. 2000©
Copyright Notice
Reproduction of this publication, or any portion thereof, by any means without the express written permission of Honeywell
International, Inc. is prohibited. For further information contact the Manager, Technical Publications; Honeywell Business &
General Aviation, Olathe, Kansas 66061. Phone [phone].

Bendix/King
KMA28
Audio Amplifier/Intercom/Marker Beacon Receiver
006-10565-0000 Page iRev. 0, Sept. 2000
Table of Contents
1 SECTION I GENERAL INFORMATION.........................................................................1-1
1.1 INTRODUCTION...........................................................................................................1-1
1.2 SCOPE.............................................................................................................................1-1
1.3 EQUIPMENT DESCRIPTION.....................................................................................1-1
1.4 APPROVAL BASIS - .....................................................................................................1-2
1.5 SPECIFICATIONS ........................................................................................................1-3
1.6 EQUIPMENT SUPPLIED.............................................................................................1-4
1.7 EQUIPMENT REQUIRED BUT NOT SUPPLIED....................................................1-5
1.8 LICENSE REQUIREMENTS.......................................................................................1-5
2 SECTION II - INSTALLATION.........................................................................................2-1
2.1 GENERAL INFORMATION........................................................................................2-1
2.1.1 SCOPE........................................................................................................................2-1
2.1.2 CERTIFICATION REQUIREMENTS.................................................................................2-1
2.2 UNPACKING AND PRELIMINARY INSPECTION................................................................2-1
2.3 EQUIPMENT INSTALLATION PROCEDURES....................................................................2-1
2.3.1 COOLING REQUIREMENTS...........................................................................................2-1
2.3.2 MOUNTING REQUIREMENTS .......................................................................................2-1
2.3.3 MOUNTING RACK INSTALLATION ...............................................................................2-2
2.3.4 CONNECTOR ASSEMBLY .............................................................................................2-2
2.4 CABLE HARNESS WIRING ...............................................................................................2-2
2.4.1 NOISE ..........................................................................................................................2-2
2.4.2 EXISTING KMA-24 INSTALLATION.............................................................................2-3
2.4.3 EXISTING PS ENGINEERING PMA6000 INSTALLATIONS ............................................2-3
2.4.4 POWER ........................................................................................................................2-3
2.4.5 COMMUNICATIONS PUSH-TO-TALK ............................................................................2-3
2.4.6 TRANSMIT INTERLOCK................................................................................................2-3
2.4.7 "SWAP" MODE ............................................................................................................2-4
2.4.8 BACKLIGHTING ...........................................................................................................2-4
2.4.9 UNSWITCHED INPUTS..................................................................................................2-4
2.4.10 INTERCOM WIRING ....................................................................................................2-4
2.4.11 COM 3 AUDIO............................................................................................................2-5
2.4.12 PUBLIC ADDRESS FUNCTION.....................................................................................2-5
2.4.13 PA MUTE (J1, PIN 18)...............................................................................................2-6
2.4.14 CONTROL OUTPUT (J2, PIN 4)...................................................................................2-6
2.4.15 VOX OVERRIDE (J2, PIN U) .....................................................................................2-6
2.5 MARKER INSTALLATION.................................................................................................2-6
2.5.1 MIDDLE MARKER SENSE ............................................................................................2-6
2.5.2 EXTERNAL MARKER LIGHTS ......................................................................................2-6
2.5.3 MARKER ANTENNA INSTALLATION ............................................................................2-6
2.6 ADJUSTMENTS..................................................................................................................2-7
2.7 COMMUNICATIONS ANTENNA INSTALLATION NOTES..................................................2-7
2.8 WIRELESS TELECOMMUNICATIONS INTERFACE ...........................................................2-7
2.8.1 HOOK SWITCHES.........................................................................................................2-8
2.9 KMA 28 PIN ASSIGNMENTS ...........................................................................................2-9
2.10 POST INSTALLATION CHECKOUT ...............................................................................2-10
2.11 UNIT INSTALLATION....................................................................................................2-10

Bendix/King
KMA28
Audio Amplifier/Intercom/Marker Beacon Receiver
006-10565-0000 Page ii Rev. 0, Sept. 2000
2.11.1 OPERATIONAL CHECKOUT ......................................................................................2-10
2.11.2 RECEIVER SENSITIVITY...........................................................................................2-11
2.12 CELLULAR INTERFACE CHECKOUT ...........................................................................2-11
2.13 FINAL INSPECTION.......................................................................................................2-11
3 SECTION III KMA28 OPERATION.................................................................................3-1
3.1 AUDIO SELECTOR............................................................................................................3-1
3.1.2 SPEAKER AMPLIFIER...................................................................................................3-1
3.1.3 PUBLIC ADDRESS (PA) FUNCTION .............................................................................3-2
3.2 POWER SWITCH /EMERGENCY (EMG) OPERATION.....................................................3-2
3.3 MICROPHONE SELECTOR................................................................................................3-2
3.3.1 SWAP MODE (SWITCH FROM COM 1 TO COM 2 REMOTELY) ...................................... 3-3
3.3.2 SPLIT MODE ................................................................................................................3-3
3.3.3 TELEPHONE MODE......................................................................................................3-3
3.4 INTERCOM SYSTEM .........................................................................................................3-4
3.4.1 INTELLIVOX® VOX-SQUELCH....................................................................................3-4
3.4.2 VOLUME CONTROL .....................................................................................................3-5
3.5 MARKER BEACON OPERATION ......................................................................................3-7
3.6 TELEPHONE OPERATION (IF EQUIPPED WITH APPROVED SYSTEM).............................3-7
4 APPENDIX A – INSTALLATION DRAWINGS ................................................................A
5 APPENDIX B BOTTOM CONNECTOR INTERCONNECT........................................... B
6 APPENDIX C TOP CONNECTOR INTERCONNECT..................................................... C
7 APPENDIX D- INSTRUCTIONS FOR FAA FORM 337 AND CONTINUING
AIRWORTHINESS......................................................................................................................D
7.1 INSTRUCTIONS FOR FAA FORM 337 ................................................................................ D
INSTRUCTIONS FOR CONTINUING AIRWORTHINESS, AUDIO PANELS .................D
APPENDIX E RTCA DO160C (EUROCAE ED-14) ENVIRONMENTAL
QUALIFICATION FORM.......................................................................................................... E

Bendix/King
KMA28
Audio Amplifier/Intercom/Marker Beacon Receiver
006-10565-0000 Page 1-1 Rev. 0, Sept. 2000
Section I GENERAL INFORMATION
1.1 INTRODUCTION
The KMA 28 represents the next step in cockpit audio control and intercommunications.
Using proprietary IntelliVox® design, this unit eliminates the requirements for intercom
squelch adjustments. The unit is designed for outstanding ergonomics and visually de-
fined mode annunciation and selection.
Before installing and/or using this product, please read this manual completely. This will
ensure that you will take full advantage of all the advanced features in the KMA 28.
1.2 SCOPE
This manual provides detailed installation and operation instructions for the Honeywell,
Inc. KMA 28 Audio Selector Panel/Intercom System
Model Description Part Number
KMA 28 Stereo Audio Panel with Marker 066-01176-0101
1.3 EQUIPMENT DESCRIPTION
The KMA 28 is a state of the art audio isolation amplifier and audio selector that contains
an automatic voice activated (VOX) intercom system. It can switch up to three transceiv-
ers (Com 1, Com 2 and Com 3) and six receivers (Nav 1, Nav 2, ADF, DME, MKR and
AUX).
The TEL mode allows the KMA 28 to act as an audio interface between aircraft head-
phone and microphones and specific aircraft approved (FAA/FCC) cellular telephone
equipment.
Warning : Use of non-aviation approved cellular telephone equipment may be prohibited by regulation.
Honeywell, Inc. is not responsible for unauthorized airborne use of cellular telephones.
There are two unswitched inputs, for autopilot disconnect, and/or radar altimeter warning.
Push buttons select the receiver audio source provided to the headphones. A SPR button
allows the user to listen to the receiver(s) selected on the cabin speaker. Except for the
unswitched inputs, all speaker audio is muted during transmit.
A rotary switch selects one of the three communication transceivers for the pilot and co-
pilot position, and allows radio transmission. In "Split Mode" the KMA 28 has the ability
to allow the pilot and copilot to operate different transceivers independently. The TEL
mode allows the pilot to use the cellular telephone interface. External switches permit
telephone operation for the copilot and passengers.
An emergency mode connects the pilot headphone and microphone to COM 1 if power is
removed for any reason, or if the power switch is placed in the Off (emergency ) position.
I
ntelliVox® is a trademark of PS Engineering, Incorporated, and used with their permission

Bendix/King
KMA28
Audio Amplifier/Intercom/Marker Beacon Receiver
006-10565-0000 Page 1-2 Rev. 0, Sept. 2000
A six-station voice activated (VOX) intercom is included in the KMA 28. This system
has the advanced IntelliVox® circuitry that eliminates manual adjustments. The system
contains six separate VOX mic circuits, and only opens the microphone channel in use.
The intercom system incorporates pilot isolate and crew modes, two stereo (or mono de-
pending on unit) music inputs with "Soft Mute," and LED indicators for swap and trans-
mit indications. Intercom control is through front panel-mounted knob and 3 position
mode switch. A single volume controls intercom level for the pilot and copilot. Passenger
headphone volume is factory set, and adjusted in flight with headset-mounted volume
controls. Passenger volume control is further adjustable through screwdriver access in the
top of the unit. Intercom squelch is automatic.
A 3-light Marker Beacon receiver is integrated in the KMA 28. This provides the neces-
sary Marker Beacon lights and audio indications necessary for an Instrument Landing
System (ILS) approach.
1.4 APPROVAL BASIS -
TSO Approval.
The KMA 28 Audio Selector Panel is FAA approved under TSO C50c (Audio Amplifi-
ers) and TSO C35d (Marker Beacon Receivers). In addition, they are approved by the
Joint Airworthiness Authorities under JTSO C50C and JAR-TSO 2C35d. The TSO
holder and manufacturer is PS Engineering, Incorporated, Lenoir City Tenn., USA.
The KMA28 complies with relevant portions of EUROCAE RTCA MPS WG No. 7/70,
DO-143 and (Marker Beacon Receivers), ED-14C/DO-160C (Environmental Conditions
and Test Procedures for Airborne Equipment), ED12B/DO-178B (Software Considera-
tions for Airborne Equipment) and ED- 18/DO-214 (Audio Systems Characteristics and
Minimum Operational Performance Standards for Aircraft Audio Systems).
Operation is subject to the following conditions:
This device may not cause harmful interference.
This device must accept any interference received, including interference that may cause
undesired operation.

Bendix/King
KMA28
Audio Amplifier/Intercom/Marker Beacon Receiver
006-10565-0000 Page 1-3 Rev. 0, Sept. 2000
1.5 SPECIFICATIONS TSO COMPLIANCE
Marker Beacon: C35d, Class A
Audio Selector/Intercom: C50c, Class A
APPLICABLE DOCUMENTS: RTCA/DO-214
RTCA/DO-143
RTCA/DO-160C
RTCA/DO-178B
ENVIRONMENTAL Qualifications: A1D1/CA(MN)XXXXXXBBBBTBKXX
Temperature Range:
Operating:
Storage:
-15º C to +55ºC
-55º C to +85ºC
Altitude: Up to 50,000 feet in an non-pressurized area of
the cockpit.
DIMENSIONS: Height: 1.3 in. (3.3 cm) Width: 6.25 in. (16.9 cm)
Depth: 6.8 in. (17.3 cm)
WEIGHT (With Rack & Connectors): 1.5 lb. (0.54 kg)
POWER REQUIREMENTS (Including Internal Lighting):
Voltage: 11 to 33 VDC
Maximum Current: 2.5 Amp (Externally protected by a 3 Amp circuit
breaker.)
Typical operating current:
Speaker off:
Speaker on, 28V, full radio volume
350 mA
1.5 A
Audio Selector Specifications
Audio selector panel input impedance:510 Ω
Input Isolation: -60 dB (min.)
Speaker Muting: -60 dB (min.)
Speaker Output (into 4 Ω) with no clipping
14 VDC:
28 VDC:
3 Watts (min.)
10 Watts (min.)
Receiver Inputs:9
(Com 1, Com 2, Com 3, Nav 1, Nav 2, ADF,
DME, MKR, AUX)
Unswitched Inputs:2
(examples: GPS WPT, Value, Autopilot Discon-
nect, Altimeter DH)
Transmitter Selections:6
(Com 1, Com 2, Com 3
Com1/2, Com2/1, Telephone)
Speaker Impedance:4 Ω
Headphone Impedance:150 - 1000 Ω
Headphone Output: 38 mW each headset, no clipping <1% THD
70 mW each headset with < 10% THD into 150Ω
Microphone Impedance:150 - 600 Ω

Bendix/King
KMA28
Audio Amplifier/Intercom/Marker Beacon Receiver
006-10565-0000 Page 1-4 Rev. 0, Sept. 2000
Intercom Specifications
Intercom Positions: 6 places (with individual IntelliVOX® circuits)
Music Inputs: 2 (Stereo)
Music Muting: >-30 dB "Soft Mute" when Com or intercom active.
Distortion: <1% THD @ 38 mW into 150Ω
<10% THD @ 70mW into 150 Ω
Mic Freq. Response, 3 dB: 300 Hz - 6000 Hz
Music Freq. Response, 3 dB: 100 Hz - 18kHz
MARKER BEACON RECEIVER
Frequency: 75 MHz Crystal Controlled
Sensitivity:
Low:
High:
Capable of:
1000 µVolts (Hard)
200 µVolts (Hard)
(preset at factory for field application)
Selectivity: -6 dB at ±10 kHz
-40 dB at ±120 kHz
External Lamp Output: 9.0 (±2.5 unloaded, at maximum brightness) VDC posi-
tive when active, max. current 125 mA
MM Sense: Active high (4.7 VDC ± 0.5V) during Middle Marker
acquisition, for autopilot use.
1.6 EQUIPMENT SUPPLIED
1 ea. of the following:
Model Part Number
KMA 28 066-01176-0101
KMA 28 Installation Kit, 050-03613-0001, contains the following parts.
Description Quantity Part
Number
KMA28 install rack 1 071-00164-0001
Top Molex Connector Shell w/key, 44 pin, key 4/5 1 120-425-4402
Bottom Molex Connector Shell w/key, 44 pin, key 7/8 1 120-425-4400
Gold Plated Crimp Pins 88 425-001-0002
4 40 X 7/16 screw w/nyl patch 4 475-440-0007
Grounding strap 1 430-007-0001
6-32 X 3/4 screw php 2 475-632-0038
6-32 Nut Flat 2 475-632-0003
6-32 Lock Nut 2 475-632-0004
Cable Clamp 1 625-001-0002
#6-32 x ½” FHP screw 6 475-632-0012
#6-32 Clip Nut 6 475-630-0002
The KMA 28 install rack may be purchased separately under part number 071-00164-0001.

Bendix/King
KMA28
Audio Amplifier/Intercom/Marker Beacon Receiver
006-10565-0000 Page 1-5 Rev. 0, Sept. 2000
1.7 EQUIPMENT REQUIRED BUT NOT SUPPLIED
a) Circuit Breaker: 1 ea. 3 amp
b) Speaker, 4 Ω
c) Headphone Jacks (Stereo, as Required)
d) Microphone Jacks (as Required)
e) Headphones, 150 Ω(Stereo), up to 6 as required
f) Microphones, up to 6 as required
g) Marker Antenna (75 MHz, VSWR <1:1.5, 50 ohm, and cable (RG400 R/U)
h) Interconnect Wiring
1.8 LICENSE REQUIREMENTS
None

Bendix/King
KMA28
Audio Amplifier/Intercom/Marker Beacon Receiver
006-10565-0000 Page 2-1 Rev. 0, Sept. 2000
Section II - Installation
2.1 GENERAL INFORMATION
2.1.1 SCOPE
This section provides detailed installation and interconnect instructions for the Honey-
well, Inc. KMA28 Audio Selector Panel/Intercom System with internal Marker Beacon.
Please read this manual carefully before beginning any installation to prevent damage and
post-installation problems. Installation of this equipment requires special tools and
knowledge.
2.1.2 Certification Requirements
When the digital audio warning system is installed in a certified aircraft, certification ba-
sis is the installer’s responsibility. Due to the variety and options available for interface,
Honeywell will only provide manufacturers’ data for our equipment interface.
2.2 Unpacking and Preliminary Inspection
Use care when unpacking the equipment. Inspect the units and parts supplied for visible
signs of shipping damage. Examine the unit for loose or broken buttons, bent knobs, etc.
Verify the correct quantity of components supplied with the list in Section 1.6. If any
claim is to be made, save the shipping material and contact the freight carrier. Do NOT
return units damaged in shipping to Honeywell. If the unit or accessories shows any sign
of external shipping damage, contact Honeywell to arrange for a replacement. Under no
circumstances attempt to install a damaged unit in an aircraft. Equipment returned to
Honeywell for any other reason should be shipped in the original packaging, or other UPS
approved packaging.
2.3 Equipment Installation Procedures
2.3.1 Cooling Requirements
Forced air cooling of the KMA 28 is not required. However the unit should be kept away
from heat producing sources (i.e. defrost or heater ducts, dropping resistors, heat produc-
ing avionics) without adequate cooling air provided.
2.3.2 Mounting Requirements
The KMA 28 must be rigidly mounted to the instrument panel of the aircraft structure and
within view and reach of the pilot position(s). Installation must comply with FAA Advi-
sory Circular AC 43.13-2A. The unit may be mounted in any area where adequate clear-
ance for the unit and associated wiring bundle exist.
Avoid installing the audio panel close to high current devices or systems with high-
voltage pulse type outputs, such as DME or transponders.

Bendix/King
KMA28
Audio Amplifier/Intercom/Marker Beacon Receiver
006-10565-0000 Page 2-2 Rev. 0, Sept. 2000
2.3.3 Mounting Rack Installation
Set the unit aside in a safe location until needed. Install the tray using six FHP 6-32 x ½"
screws. The audio selector panel must be supported at front and rear of the mounting tray.
2.3.4 Connector Assembly
The unit connectors mate directly with the circuit boards in the KMA 28. The connectors
are a Molex crimp-type, and require the use of a Molex hand crimp tool, EDP P/N 11-01-
0203, CR6115B (or equiv.). The connectors are mounted to the unit tray with #4-40
screws, from the inside of the tray. Ensure that proper strain relief and chafing precau-
tions are made during wiring and installation.
2.4 Cable Harness Wiring
Referring to the appropriate Appendix, assemble a wiring harness as required for the in-
stallation. All wires must be MIL-SPEC in accordance with current regulations. Two- and
three-conductor shielded wire must be used where indicated, and be MIL-C-27500 or
equivalent specification. Proper stripping, shielding and soldering technique must be used
at all times. It is imperative that correct wire be used.
Refer to FAA Advisory Circular 43.13-2A for more information. Failure to use correct
techniques may result in improper operation, electrical noise or unit failure. Damage
caused by improper installation will void the warranty.
2.4.1 Noise
Due to the variety and the high power of radio equipment often found in today's general
aviation aircraft, there is a potential for both radiated and conducted noise interference.
The KMA 28 power supply is specifically designed to reduce conducted electrical noise
on the aircraft power bus by at least 50dB. Although this is a large amount of attenuation,
it may not eliminate all noise, particularly if the amplitude of noise is very high. There
must be at least 13.8 VDC present at the bottom connector, pin 20, of the KMA 28 for the
power supply to work in its designed regulation. Otherwise, it cannot adequately attenuate
power line noise. Shielding can reduce or prevent radiated noise (i.e., beacon, electric gy-
ros, switching power supplies, etc.) However, installation combinations can occur where
interference is possible. The KMA 28 was designed in a RFI hardened chassis and has
internal Electromagnetic Interference (EMI) filters on all inputs and outputs.
Ground loop noise occurs when there are two or more ground paths for the same signal
(i.e., airframe and ground return wire). Large cyclic loads such as strobes, inverters, etc.,
can inject noise signals onto the airframe that are detected by the audio system. Follow
the wiring diagram very carefully to help ensure a minimum of ground loop potential. Use
only Mil Spec shielded wires (MIL-C-275000, or better).
Radiated signals can be a factor when low level microphone signals are "bundled" with
current carrying power wires. Keep these cables physically separated. It is very important

Bendix/King
KMA28
Audio Amplifier/Intercom/Marker Beacon Receiver
006-10565-0000 Page 2-3 Rev. 0, Sept. 2000
that you use insulated washers to isolate the ground return path from the airframe to all
headphone and microphone jacks.
2.4.2 Existing KMA-24 Installation
If the installation replaces a KMA-24 (series –00, -01, -02 or -03), the existing 44 pin
connector can be used for the bottom connector of the KMA 28 tray as is, providing it is
properly installed and wired. No other changes are required except for external marker
lights (see Appendix B for details). The "key" in the existing connector must be located
between pins 7 and 8. This connector will be used in the bottom connector position. (See
Appendix for complete wiring harness details.)
The existing ground bus may be reused for radio shield connections, if it was constructed
so it can be relocated to the KMA 28 tray.
2.4.3 Existing PS Engineering PMA6000 installations
In 28-Volt aircraft, the dropping resistor may be removed, however, the 2 Amp breaker
should be changed to 3 Amp. If either old unit is stereo (PMA6000S or PMA6000MS),
no rewiring is necessary unless additional features are added.
2.4.3.1 Stereo KMA 28 installations into existing monaural PS Engineering
PMA6000, PMA6000M.
Installations replacing PMA6000 or PMA6000M require re-wiring of the top connector to
accommodate the stereo configuration. See appendixes for detailed interconnect informa-
tion.
2.4.4 Power
The KMA 28 is compatible with both 14 and 28 Volt DC systems. A two (2) Amp circuit
breaker is required for 14 VDC installations, and a three (3) Amp breaker for 28 VDC
aircraft. Power and ground wires must be a twisted #18 AWG pair. Connect airframe
power ground to J1 (bottom connector) Pin Z only. No dropping resistors are required.
2.4.5 Communications Push-to-Talk
An important part of the installation is the PTT (Push-To-Talk) switches that allow the
use of your aircraft communications radio for transmissions. Only the person who presses
their PTT switch will be heard over the radio. If the pilot and copilot both use the PTT,
only the pilot position has access to the radio. The pilot position will have PTT control
regardless of the mic selector switch or copilot PTT when the KMA 28 is in the
EMERGENCY mode.
2.4.6 Transmit Interlock
Some communications transceivers use a transmit-interlock system. To fully utilize the
Split Mode feature, this function must be disabled. Consult that manufacturer's installa-
tion manual.

Bendix/King
KMA28
Audio Amplifier/Intercom/Marker Beacon Receiver
006-10565-0000 Page 2-4 Rev. 0, Sept. 2000
2.4.7 "Swap" Mode
When a momentary, normally open, push-button switch is connected between pin 10 on
the top connector and aircraft ground, the user can switch between Com 1 and 2 by de-
pressing this switch without having to turn the mic selector switch. This yoke-mounted
switch eliminates the need to remove your hands from the yoke to change transceivers.
2.4.8 Backlighting
The KMA 28 has an automatic dimming of the pushbutton annunciator LEDs and marker
lamps controlled by a photocell. Control of the unit backlighting is through the aircraft
avionics dimmer. Connect the dimmer control line to J1 pin D for 14 volt systems, and to
J1 pin F for 28 volt systems. Pin E is light ground.
If an external dimmer control is not used, a constant low level back light illumination can
be established for nighttime viewing. Pin D or F (depending on system voltage) must be
tied to power (J1, pin 20) for the back lighting system to work. The photocell mounted in
the unit face will automatically adjust the intensity of the push-button annunciator LEDs.
2.4.9 Unswitched inputs
J1, pin T is the unswitched input number 1 and J1 pin 17 is unswitched input 2. These
inputs are presented to the pilot and copilot regardless of the audio configuration, and will
always mute the entertainment inputs. These 510Ωinputs can be used for altimeter DH
audio, GPS waypoint audio, autopilot disconnect tones, air-to-ground (Flitefone) tele-
phone ringer or any other critical audio signal. This input is not related to the cellular
telephone interface.
2.4.10 Intercom wiring
The top connector (J2) is for the intercom and additional functions. See Appendix for in-
tercom connection configurations. It is critical to the proper operation of this system to
have this connector wiring made in accordance with these diagrams. Use 2- and 3-
conductor, MIL-spec cable as shown. Connect the shields at the audio panel end only, and
tie to the audio low inputs as shown.
2.4.10.1 Entertainment Input
NOTE: Use the low level output of any entertainment device to connect to
the audio panel. Maximum signal level is 1 VAC p-p.
DO NOT use a speaker-level output, this will cause internal damage in the
audio panel
2.4.10.1.1Stereo entertainment
Two stereo entertainment devices (CD player, cassette player, etc.) can be connected to
the unit. Install two 1/8-inch stereo jacks in a convenient location so that the pilot can plug

Bendix/King
KMA28
Audio Amplifier/Intercom/Marker Beacon Receiver
006-10565-0000 Page 2-5 Rev. 0, Sept. 2000
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.
2.4.10.1.2Entertainment 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-
vices.
All entertainment devices must be switched off for both takeoff and landing.
2.4.10.1.3Entertainment 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-
tance.
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

Bendix/King
KMA28
Audio Amplifier/Intercom/Marker Beacon Receiver
006-10565-0000 Page 2-6 Rev. 0, Sept. 2000
pilot’s PTT is activated, his voice is heard over the speaker. The copilot can continue to
use the selected com.
We recommend installing a toggle switch to connect the cabin speaker output (pin W,
bottom connector) to a rear or public address speaker instead of the cockpit speaker close
to the pilot. This will prevent feedback.
2.4.13 PA Mute (J1, Pin 18)
Pin 18 of J1 is a TTL logic output that is pulled low during PTT operation. This serves as
an input to external public address system to prevent feedback during transmissions.
2.4.14 Control Output (J2, Pin A)
Pin A of the top connector is pulled to ground whenever the AUX button is depressed.
This serves as a control line for external devices, such as a entertainment system that the
pilot wishes to control.
2.4.15 VOX Override (J2, Pin U)
Connecting pin U of the KMA 28 of J2 to ground will force the IntelliVox® open. This
can be hooked up as a hot mic switch which will place all microphones on the intercom.
This can also be connected through a momentary switch to serve as a VOX test switch, if
desired. Because the IntelliVox® will close in the presence of a steady tone, this pin is
used in testing to defeat the IntelliVox® software.
2.5 Marker Installation
The marker beacon receiver is included in the KMA 28.
2.5.1 Middle Marker Sense
A Middle Marker sense output signal is available from the KMA28 to flight control sys-
tems. This function will not operate during the test mode. This output will go to +4.7
VDC (±0.5 VDC) when a valid Middle Marker signal is received. This output is J1, pin
2.
2.5.2 External Marker Lights
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 (+9 VDC ±1.5
VDC) when active. Maximum source current per lamp is 125 mA. Voltage varies with
photocell dimming.
2.5.3 Marker Antenna Installation
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 tech-
niques. The marker beacon antenna must be mounted on the bottom of the aircraft.

Bendix/King
KMA28
Audio Amplifier/Intercom/Marker Beacon Receiver
006-10565-0000 Page 2-7 Rev. 0, Sept. 2000
2.6 Adjustments
The KMA 28 is factory adjusted to accommodate the typical requirements for most air-
craft configurations. There are five adjustments however, that will allow the installer to
tailor the specific functions.
Marker Gain
CW- Reduce
Passenger Volume
CCW Increases
Marker Audio
CW Decrease Volume
MKR Low Sense
CW Decrease Sens.
Front of Unit
KMA28 adjustment holes
Not used
Speaker Volume
CW-Increase
211
231
223
133
111
Figure 2-1- KMA 28 Adjustments
2.7 Communications Antenna Installation Notes
For best results while in Split Mode, it is suggested that the one VHF communications
antenna is located on top of the aircraft while the other communications antenna is in-
stalled on the bottom. Any antenna relocation must be accomplished in accordance with
AC 43.13-2A, aircraft manufacturers’ recommendations and FAA-approved technical
data.
Warning:
Itisprobable that radio interference will occur in the split mode when the frequencies
of the two aircraft radios are adjacent, and/or the antennas are physically close to-
gether. Honeywell makes no expressed or implied warranties regarding the suitability
of the KMA 28 in Split Mode.
2.8 Wireless telecommunications interface
The KMA 28 has interface capability with units such as the AirCell units. It is the user’s
responsibility to determine the appropriate legal use of the equiment, and provide the
services.
Interface to the AirCell unit is through J1 (bottom) connector, pins 14 and N. Pin 14, la-
beled cellphone ring, is connected to pin V of the 3100D J3 connector and pin N of J1 is

Bendix/King
KMA28
Audio Amplifier/Intercom/Marker Beacon Receiver
006-10565-0000 Page 2-8 Rev. 0, Sept. 2000
connected to pin W of the J3 connector. On the AirCell interface diagram these are listed
as data/fax lines, but they are used for voice interface in this case.
Use a 2-conductor with shield cable, and connect the shield to Pin M of the J3.
If interface is desired with another type of wireless telecommunications unit, the aircraft
owner can purchase an after-market interface cable. By Federal Communications Com-
mission (FCC) regulations, these can only be used on the ground in the United States.
Unauthorized use of cellular telephone devices in aircraft is subject to FCC enforcement action,
which may include a $10,000 fine per incident. Honeywell, Inc. does not endorse using unapproved
cellular telephone equipment in flight, and takes no responsibility for the user’s action.
2.8.1 Hook Switches
While the mic selector acts as the hook switch for the pilot, additional hook switches
must be installed to have full access to the cellphone system. The copilot hook switch is a
SPST switch that connects pin L of J2 on the KMA 28 to ground to place the copilot on
the cellphone.
KMA 28 J2, pin M is the passenger hook switch. Install a SPST switch in a location adja-
cent to each passenger headset where cellphone use is desired. When pin M is connected
to ground through any switch, the passenger microphones are all on the cellphone system.
The wireless communication “tel” system utilizes an intercom loop. Therefore, any time
the cellphone is in use from the pilot or copilot side, pilot and copilot will lose intercom
capability. In the ALL mode, when the passengers’ activate the cell phone, the pilots will
have intercom, and continue to hear and transmit over the avionics normally. However
the passengers will not have intercom, because they are on the telephone.
To prevent unwanted distractions, only the pilot and copilot will hear an incoming call
ring signal. They can then decide to allow a passenger to activate the hook switch and use
the telephone.
If the pilot has selected “TEL” mode, the passengers cannot access the telephone in the
“CREW” intercom mode, but they will hear the call.

Bendix/King
KMA28
Audio Amplifier/Intercom/Marker Beacon Receiver
006-10565-0000 Page 2-9 Rev. 0, Sept. 2000
2.9 KMA 28 Pin Assignments
Pilot Phone Audio Hi (Left)
Copilot Phone Audio (Lt)
Copilot Phone Audio Lo
Copilot Phone Audio (Rt)
Pass 1 Mic Audio Hi
Pass 1 Mic Audio Lo
Pass 2 Mic Audio Lo
Pass 2 Mic Audio Hi
Pass 3 Mic Audio Hi
Pass 3 Mic Audio Lo
Pass 4 Mic Audio Hi
Copilot Mic Audio Hi
Pass Cellphone Off Hook
Copilot Mic Key
Copilot Mic Audio Lo
Swap Switch
Pass 4 Mic Audio Lo
Copilot Cellphone Off Hook
Passenger Headphone Audio (R)
Passenger Headphone Audio (L)
Passenger Headphone Audio Lo
Entertainment #2 In (R)
Entertainment #1 In (R)
Ent 2 Mute
Entertainment # 2 Lo
Entertainment #1 In (L)
Entertainment #1 Lo
Ground
IntelliVOX Over ride
Reserved
1
A
2
B
3
C
4
D
5
E
6
F
7
H
8
J
9
K
10
L
11
M
12
N
13
P
14
R
15
S
16
T
17
U
18
V
19
W
20
X
21
Y
22
Z
Entertainment #2 In (L)
J2 Top Connector
Pilot Mic Audio Hi In
Com 3 Audio Hi
Com 1 Audio Hi
Com 2 SPKR Load
AUX Audio Input Hi
Com 1 Spkr Load
Com 2 Audio Hi
Aircraft Power 11-33 VDC
ADF Audio Hi
Com 2 SPKR load
Unswitched Audio In #1
Unswitched Audio In #2
Com 3 Mic Key
Com 1 Mic Key
Nav 2 Audio Hi
Com 1 Mic Audio Out
Cellphone ring
Cellphone tip
Nav 1 Audio Hi
Com 2 Mic Audio Out
28V Lights Hi
Light Lo
14 V Light Hi
Amber Lamp Out
PA Mute
Chassis Ground
Aircraft Ground
Cabin Spkr Lo
Pilot Mic Key
Cabin Spkr Out
Com 1 SPKR load
DME Audio Hi
Blue Lamp Out
White Lamp Output
Pilot Headphones
MM Sense Output
MKR Coax Lo
Com 3 Mic Audio Out
Com 2 Mic Key
MKR Antenna
1
A
2
B
3
C
4
D
5
E
6
F
7
H
8
J
9
K
10
L
11
M
12
N
13
P
14
R
15
S
16
T
17
U
18
V
19
W
20
X
21
Y
22
Z
J1 Bottom Connector
Ext. Marker Audio In
PA Activate
AUX Control Out
Reserved
Reserved
Reserved
Reserved
Reserved
Reserved
Reserved

Bendix/King
KMA28
Audio Amplifier/Intercom/Marker Beacon Receiver
006-10565-0000 Page 2-10 Rev. 0, Sept. 2000
2.10 Post Installation Checkout
After wiring is complete, verify power is ONLY on pin 20 of the J1 (bottom connector),
and airframe ground on bottom connector pin Z. Failure to do so will cause serious inter-
nal damage and void the warranty.
2.11 Unit Installation
To install the KMA 28, gently slide the unit into the mounting rack until the hold-down
screw is engaged. While applying gentle pressure to the face of the unit, tighten the 3/32"
hex-head in the center of the unit until it is secure. DO NOT OVER TIGHTEN.
Warning: Do not over-tighten the lock down screw while installing the
unit in tray. Internal damage will result.
2.11.1 Operational Checkout
1. Apply power to the aircraft and avionics. Switch on the unit by pressing the volume
knob.
2. Plug headsets into the pilot, copilot, and occupied passenger positions.
3. Rotate the Mic Selector Switch to the Com 1 position.
4. Verify that the Com 1 button lights. Verify that the green transmit LED (Light Emit-
ting Diode) near the mic selector is not illuminated. If the LED is on, stop testing and
troubleshoot the microphone PTT installation.
5. Verify proper transmit and receive operation from the copilot position, noting that the
copilot PTT switch allows proper transmission on the selected transceiver.
6. Verify that pushing the COM 2 button causes the button to illuminate, and the Com 2
receiver to be heard. Verify operation on Com 1 from the pilot position.
7. Repeat for Com 2 and Com 3, (if installed).
8. Rotate the mic selector switch to the COM 1/2 position. Verify that the pilot commu-
nicates on Com 1 and the copilot on Com 2.
9. Rotate the mic selector switch to the COM 2/1 position. Verify that the pilot commu-
nicates on Com 2 and the copilot on Com 1.
10. Rotate the mic selector switch to the TEL position. Verify that the pilot headset is
connected to the cellular telephone system (if installed). Verify that by using the pilot
side PTT, the pilot can transmit on Com 1. The copilot has no transmit capability in
TEL mode.
11. Verify proper operation of all receiver sources by selecting them using the button.
Note that the button for the receiver sources stays in, and the button illuminates to
show which source is in use.
12. Push in the SPR button. Verify that all selected audio is heard in the cockpit speaker.
Verify that the audio mutes when the mic is keyed.
13. Verify that the LED in the lower right side illuminates when either push to talk is
keyed.
14. Verify proper Intercom system operation in the ALL, ISO and CREW modes (see Ta-
ble 3-1).

Bendix/King
KMA28
Audio Amplifier/Intercom/Marker Beacon Receiver
006-10565-0000 Page 2-11 Rev. 0, Sept. 2000
15. Verify that the audio selector panel system does not adversely affect any other aircraft
system by systematically switching the unit on and off, while monitoring the other
avionics and electrical equipment on the aircraft.
2.11.1.1 Marker Checkout
1. Connect a ramp generator at the antenna end of the marker coax. With the unit under
test in HI sensitivity, verify that a 160 µV, modulated 95% with 1300 Hz, signal will
illuminate the amber (M) marker light, and that marker audio is present in the head-
phones when the Marker Audio (MKR) push-button has been depressed. Select SPR
for speaker to verify marker audio availability on the cabin speaker. Verify that the
white (A) and blue (O) lights will illuminate within ±3dB of the amber lamp, with
3000 HZ and 400 Hz applied, respectively.
2. Repeat with the unit in LOW sensitivity, with 430 µVolts applied.
3. Connect the marker antenna and verify proper operation.
2.11.2 Receiver Sensitivity
Although the KMA28 meets FAA TSO-C35d sensitivity specifications, the sensitivity of
the receiver has been adjusted to meet real world requirements (150µV and 430µV, soft).
This will usually eliminate the need for the avionics shop to reduce the sensitivity in the
field so as to prevent early detection of the marker beacons. If your particular installation
requires more or less sensitivity, see adjustment section 2.6, and figure 2-1.
2.12 Cellular Interface Checkout
When a wireless telecommunication system is installed and configured, a dial tone will
appear in the headset of the pilot when the mic selector is in the “Tel” position. In “ALL”
intercom mode, a dial tone will be heard whenever the copilot or passenger’s hook switch
is closed.
2.13 Final Inspection
Verify that the wiring is bundled away from all controls and no part of the installation in-
terferes with aircraft control operation. Move all controls through their full range while
examining the installation to see that no mechanical interference exists. Verify that the
cables are secured to the aircraft structure in accordance with good practices, with ade-
quate strain relief. Ensure that there are no kinks or sharp bends in the cables and coaxial
cables. Verify that the cables are not exposed to any sharp edges or rough surfaces, and
that all contact points are protected from abrasion.
Complete log book entry, FAA Form 337, weight and balance computation and other
documentation as required. Sample text for FAA Form 337, and instructions for continu-
ing airworthiness can be found in Appendix D.
Return completed warranty registration application.

Bendix/King
KMA28
Audio Amplifier/Intercom/Marker Beacon Receiver
006-10565-0000 3-1 Rev. 0, Sept. 00
Section III KMA28 OPERATION
GENERAL INFORMATION
KMA28 controls
3.1 Audio Selector
Receiver audio is selected through two momentary and six latched, push-button, backlit
switches. Com 1 and Com 2 are the momentary switches.
Because the rotary microphone selector switch controls what transceiver is being heard,
the Com l and Com 2 push-buttons are of the momentary type and do not remain in when
selected. This is also part of the "auto” function. You will always hear the audio from the
transceiver that is selected for transmit by the rotary mic selector switch.
The users can identify which receivers are selected by noting which of the green switch
LEDs are illuminated. Push buttons labeled Nav 1, Nav 2, DME, MKR (Marker), ADF,
AUX (auxiliary), and SPR (Speaker) are "latched" type switches. When one of these
buttons is pressed, it will stay in the "in" position. Press the switch again and it will be in
the "out" position and remove that receiver from the audio.
3.1.1.1 Key “click”
The KMA28 is equipped with an electronic “click” to provide additional feedback for
button operation. To activate the key click, push and hold BOTH COM 1 and COM 2 re-
ceiver buttons for five seconds, and release. Repeat to defeat the click.
3.1.2 Speaker Amplifier
The "SPR" in the push-button section stands for speaker. This switch will place all se-
lected audio on the cockpit speaker when this switch is selected.