PS Engineering PMA7000S, PMA7000M-S Installation And Operation Manual
9800 Martel Road
Lenoir City, TN 37772
PMA7000S
PMA7000M-S
with Options
Com 1/2
V
o
l
u
m
e
O
M
I
Push
(Fail-Safe)
High
Com 1 Nav 1
Low
Test
Iso
All
Crew
Nav 2Com 2
ENGINEERING
INCORPORATED
Com 1
MKR ADF
AUXICS
R
PMA7000M-S
DME
SPR
Com 2
Com 3
Transmit Swap
Document P/N 200-070-0006
Revision 6, Nov 1998
FAA-Approved TSO C50c, C35d
High-fidelity Stereo Audio Selector Panel
Intercom System
Installation and Operation Manual
In certified aircraft, warranty is not valid unless this product is installed by
an Authorized PS Engineering dealer.
Com 2/1
Tel
Any reproduction or retransmittal of this publication, or any portion thereof, without the expressed written permission of PS
Engineering, Inc. is strictly prohibited. For further information contact the Publications Manager at PS Engineering, Inc., 9800
Martel Road, Lenoir City, TN 37772. Phone (423) 988-9800
PS Engineering, Inc. 1998 ©
Copyright Notice
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 - FAA........................................................................................ 1-2
1.5 SPECIFICATIONS.................................................................................................... 1-3
1.6 EQUIPMENT SUPPLIED......................................................................................... 1-4
1.7 EQUIPMENT REQUIRED BUT NOT SUPPLIED................................................. 1-4
1.8 LICENSE REQUIREMENTS ................................................................................... 1-4
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 ................................................................ 2-2
2.3.1 COOLING REQUIREMENTS ...................................................................................... 2-2
2.3.2 MOUNTING REQUIREMENTS ................................................................................... 2-2
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 .................................................................................................................... 2-3
2.4.2 EXISTING KMA-24 INSTALLATION ......................................................................... 2-3
2.4.3 EXISTING PMA6000 INSTALLATIONS...................................................................... 2-3
2.4.4 POWER................................................................................................................... 2-4
2.4.5 EXTERNAL PUSH-TO-TALK..................................................................................... 2-4
2.4.6 TRANSMIT INTERLOCK........................................................................................... 2-4
2.4.7 "SWAP" MODE ....................................................................................................... 2-4
2.4.8 BACKLIGHTING ...................................................................................................... 2-4
2.4.9 UNSWITCHED INPUTS ............................................................................................. 2-5
2.4.10 INTERCOM WIRING................................................................................................2-5
2.4.11 COM 3 AUDIO.......................................................................................................2-6
2.4.12 PA MUTE (J1, PIN 18).......................................................................................... 2-6
2.4.13 VOX OVERRIDE (J2, PIN U)................................................................................. 2-6
2.4.14 IRS INSTALLATION (OPTION 1, AND 2) ................................................................. 2-7
2.4.15 AUDIO MESSAGE INSTALLATION (OPTION 1 AND 2 ONLY)..................................... 2-7
2.5 MARKER INSTALLATION (PMA7000M-S) ................................................................. 2-7
2.5.1 MIDDLE MARKER SENSE........................................................................................ 2-7
2.5.2 EXTERNAL MARKER LIGHTS (7000MS).................................................................. 2-8
2.5.3 MARKER ANTENNA INSTALLATION......................................................................... 2-8
2.5.4 MARKER INPUT (7000, 7000S)............................................................................... 2-8
2.6 ADJUSTMENTS ............................................................................................................ 2-8
2.7 COMMUNICATIONS ANTENNA INSTALLATION NOTES............................................... 2-8
2.8 WIRELESS TELECOMMUNICATIONS INTERFACE........................................................ 2-9
2.8.1 HOOK SWITCHES.................................................................................................... 2-9
2.9 PMA7000M-S PIN ASSIGNMENTS ............................................................................ 2-11
PMA7000M-S Series Audio Selector Panel and Intercom System
PS Engineering
Installation and Operator’s Manual
2.10 POST INSTALLATION CHECKOUT........................................................................... 2-12
2.11 UNIT INSTALLATION............................................................................................... 2-12
2.11.1 OPERATIONAL CHECKOUT.................................................................................. 2-12
2.11.2 RECEIVER SENSITIVITY....................................................................................... 2-13
2.12 CELLULAR INTERFACE CHECKOUT ....................................................................... 2-13
2.13 INTERNAL RECORDER CHECKOUT......................................................................... 2-13
2.14 DIGITAL ANNUNCIATION CHECKOUT.................................................................... 2-14
2.15 FINAL INSPECTION.................................................................................................. 2-14
3 SECTION III OPERATION .......................................................................................... 3-1
3.1 SCOPE .......................................................................................................................3-1
3.2 AUDIO SELECTOR (ALL MODELS).............................................................................. 3-1
3.2.1 SPEAKER AMPLIFIER .............................................................................................. 3-2
3.3 POWER SWITCH (FAIL SAFE OPERATION)................................................................. 3-2
3.4 MICROPHONE SELECTOR........................................................................................... 3-2
3.4.1 SWAP MODE (SWITCH FROM COM 1 TO COM 2 REMOTELY) ................................... 3-3
3.5 SPLIT MODE ............................................................................................................... 3-3
3.5.1 SPLIT MODE ICS.................................................................................................... 3-3
3.6 INTERCOM .................................................................................................................. 3-4
3.6.1 INTELLIVOX™ VOX-SQUELCH ............................................................................... 3-4
3.6.2 VOLUME CONTROL ................................................................................................ 3-4
3.6.3 INTERCOM MODES................................................................................................. 3-5
3.7 TELEPHONE MODE..................................................................................................... 3-6
3.8 MARKER BEACON (PMA7000M-S)............................................................................ 3-7
3.9 INTERNAL RECORDER SYSTEM (OPTION 1 AND 2 ONLY).......................................... 3-7
3.9.1 OPERATION............................................................................................................ 3-8
4 SECTION IV- WARRANTY AND SERVICE ............................................................... 4-1
4.1 WARRANTY................................................................................................................. 4-1
4.2 FACTORY SERVICE ..................................................................................................... 4-1
5 APPENDIX A EXTERNAL PTT HOOK UP ................................................................... A
6 APPENDIX B – INSTALLATION DRAWING ................................................................ B
7 APPENDIX C BOTTOM CONNECTOR INTERCONNECT ......................................... C
8 APPENDIX D TOP CONNECTOR INTERCONNECT ................................................... D
9 APPENDIX E- INSTRUCTIONS FOR FAA FORM 337 AND CONTINUING
AIRWORTHINESS ................................................................................................................. E
9.1 INSTRUCTIONS FOR FAA FORM 337, AUDIO PANELS................................................... E
INSTRUCTIONS FOR CONTINUING AIRWORTHINESS, AUDIO PANELS ................. E
10 APPENDIX F RTCA DO160C ENVIRONMENTAL QUALIFICATION FORM ......... F
200-070-0006 Page ii Rev 5, Nov 98
PMA7000M-S Series Audio Selector Panel and Intercom System
PS Engineering
Installation and Operator’s Manual
1 Section I GENERAL INFORMATION
1.1 INTRODUCTION
The PMA7000M-S 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
defined 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 PMA7000M-S.
1.2 SCOPE
This manual provides detailed installation and operation instructions for the PS Engineering PMA7000M-S-series of Audio Selector Panel/Intercom Systems. This includes the
following units:
Model Description Part Number
PMA7000S Stereo Audio Selector Panel 7000S
PMA7000M-S Stereo Audio Panel with Marker 7000MS
Option 1 added to any unit Same as above, with optional recorder and mes-
sage system
Option 2 added to any unit Same as above, with optional recorder and mes-
sage system for Vista Map Software
Option 3 added to any system Black bezel (no silver trim) Opt 3
Opt.1
Opt 2
Where the functions are identical to all units, it will be referred to herein as a PMA7000MS. Otherwise, the applicable units will be specified.
1.3 EQUIPMENT DESCRIPTION
The PMA7000M-S-series 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 transceivers (Com 1, Com 2 and Com 3) and six receivers (Nav 1, Nav 2, ADF,
DME, MKR and AUX).
The TEL mode allows the PMA7000M-S to act as an audio interface between aircraft
headphone and microphones and specific aircraft approved (FAA/FCC) cellular telephone
equipment.
Warning
: Use of non-aviation approved cellular telephone equipment is prohibited by regul ation.
PS Engineering is not responsible for unauthorized use of cellular telephones.
The PMA7000M-S is only interfaced to the Trimble TrimConnect 3100 D at this time.
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
200-070-0006 Page 1-1 Rev. 6, Nov 98
PMA7000M-S Series Audio Selector Panel and Intercom System
PS Engineering
Installation and Operator’s Manual
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 copilot position, and allows radio transmission. In "Split Mode" the PMA7000M-S 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.
A fail-safe 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 (Fail-safe) position.
A six-station voice activated (VOX) intercom is included in the PMA7000M-S. This system has PS Engineering’s exclusive 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 depending on unit) music inputs with "Soft Mute," and LED indicators for swap and transmit 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.
An optional 3-light Marker Beacon receiver is integrated in the PMA7000M-S. This provides the necessary Marker Beacon lights and audio indications necessary for an Instrument Landing System (ILS) approach.
1.4 APPROVAL BASIS - FAA
TSO Approval.
The PMA7000M-S, and PMA7000S Audio Selector Panels are FAA approved under
TSO C50c (Audio Amplifiers) and TSO C35d (Marker Beacon Receivers).
All systems comply with relevant portions of RTCA DO-143 (Marker Beacon Receivers),
DO-160C (Environmental Conditions and Test Procedures for Airborne Equipment),
DO-178B (Software Considerations for Airborne Equipment) and DO-214 (Audio Sys-
tems Characteristics and Minimum Operational Performance Standards for Aircraft
Audio Systems).
NOTE: The optional message annunciators contained in Option 1 and Option 2 are not
TSO-approved, and the installer must determine the relevant approval basis prior to installation. Contact PS Engineering for information regarding FAA approval.
200-070-0006 Page 1-2 Rev. 6, Nov 98
PMA7000M-S Series Audio Selector Panel and Intercom System
PS Engineering
Installation and Operator’s Manual
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.
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:
Altitude: Up to 50,000 feet in an unpressurized area of the
DIMENSIONS: Height: 1.3 in. (3.3 cm) Width: 6.25 in. (16.9 cm)
WEIGHT (With Rack & Connectors): 1.5 lb. (0.54 kg)
POWER REQUIREMENTS (Including Internal Lighting):
Voltage: 11 to 33 VDC
Maximum Current: 1.5 Amp (Externally protected by a 3 Amp circuit
Typical operating current:
Speaker off:
Speaker on, 28V, full radio volume
Audio Selector Specifications
Audio selector panel input impedance:
Input Isolation: -60 dB (min.)
Speaker Muting: -60 dB (min.)
Speaker Output (into 4 Ω) with no clipping
14 VDC:
28 VDC:
Receiver Inputs: 9
Unswitched Inputs: 2
Transmitter Selections: 6
Speaker Impedance:
Headphone Impedance:
Headphone Output: 38 mW each headset, no clipping <1% THD
Microphone Impedance:
-20º C to 55ºC
-40º C to 85ºC
cockpit.
Depth: 6.8 in. (17.3 cm)
breaker.)
350 mA
1.5 A
510 Ω
3 Watts (min.)
10 Watts (min.)
(Com 1, Com 2, Com 3, Nav 1, Nav 2, ADF,
DME, MKR, AUX)
(examples: GPS WPT, Value, Autopilot Disconnect, Altimeter DH)
(Com 1, Com 2, Com 3
Com1/2, Com2/1, Telephone)
4 Ω
150 - 1000 Ω
70 mW each headset with < 10% THD into 150Ω
150 - 600 Ω
200-070-0006 Page 1-3 Rev. 6, Nov 98
PMA7000M-S Series Audio Selector Panel and Intercom System
Intercom Positions: 6 places (with individual IntelliVOX circuits)
Music Inputs: 2 (Stereo)
Music Muting: >-50 dB "Soft Mute" when Com or intercom ac-
Distortion:
Mic Freq. Response, 3 dB: 300 Hz - 6000 Hz
Music Freq. Response, 3 dB: 100 Hz - 18kHz
MARKER BEACON RECEIVER:PMA7000M-S only
Frequency: 75 MHz Crystal Controlled
Sensitivity:
Low:
High:
Selectivity: -6 dB at ±110 kHz
External Lamp Output: 9.0 (±2.5 photocell dimmed) VDC positive when
MM Sense: Active high (4.7 VDC ± 0.5V) during Middle
PS Engineering
Installation and Operator’s Manual
Intercom Specifications
tive.
<1% THD @ 38 mW into 150Ω
<10% THD @ 70mW into 150 Ω
1000 µVolts (Hard)
200 µVolts (Hard)
(Field Adjustable)
-40 dB at ±120 kHz
active, max. current 125 mA
Marker acquisition, for autopilot use.
1.6 EQUIPMENT SUPPLIED
1 ea. of the following units:
Model Part Number
PMA7000S 7000S
PMA7000M-S 7000M-S
PMA7000M-S Installation Kit: 250-007-002
Part Number Description Quantity
001-006-0001 Tray with (2) 44 Pin Connectors 1
655-000-0001 Gold Plated Crimp Pins 88
200-070-0001 Operator's and Installation Manual 1
1.7 EQUIPMENT REQUIRED BUT NOT SUPPLIED
a) Circuit Breaker: 1 ea. 2 amp. (14V) or 3 amp (28V)
b) Speaker, 4 Ω
c) Headphone Jacks (mono or stereo, as Required)
d) Microphone Jacks (as Required)
e) Headphones, 150 Ω (mono or stereo), up to 6 as required
f) Microphones, up to 6 as required
g) Marker Antenna (75 MHz, VSWR <1:1.5, and appropriate for the airspeed)
h) Interconnect Wiring
1.8 LICENSE REQUIREMENTS
None
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PMA7000M-S Series Audio Selector Panel and Intercom System
PS Engineering
Installation and Operator’s Manual
2 Section II - Installation
2.1 GENERAL INFORMATION
2.1.1 SCOPE
This section provides detailed installation and interconnect instructions for the PS Engineering PMA7000S-Series Audio Selector Panel/Intercom System and PMA7000M-SSeries Audio Selector Panel/Intercom System with internal Marker Beacon.
With the exception of the internal marker beacon receiver, the PMA7000S, and
PMA7000M-S are identical. All units will be identified hereafter as the PMA7000M-S,
where the information applies to all.
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.
NOTE: An appropriately rated Certified Aircraft Repair Station must install this equipment in accordance with applicable regulations. PS Engineering, Incorporated warranty is
not valid unless the equipment is installed by an authorized PS Engineering, Incorporated
dealer. Failure to follow any of the installation instructions, or installation by a noncertified individual or agency will void the warranty, and may result in an unairworthy installation.
2.1.2 Certification Requirements
When the digital audio warning system is installed in a certified aircraft, certification basis
is the installer’s responsibility. Due to the variety and options available for interface, PS
Engineering, will only provide manufacturers data for our equipment interface. Contact PS
Engineering for more details.
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 (B). If any
claim is to be made, save the shipping material and contact the freight carrier. Do NOT
return units damaged in shipping to PS Engineering. If the unit or accessories shows any
sign of external shipping damage, contact PS Engineering to arrange for a replacement.
Under no circumstances attempt to install a damaged unit in an aircraft. Equipment returned to PS Engineering for any other reason should be shipped in the original PS Engineering packaging, or other UPS approved packaging.
200-070-0006 Page 2-1 Rev. 6, Nov 98
PMA7000M-S Series Audio Selector Panel and Intercom System
PS Engineering
Installation and Operator’s Manual
2.3 Equipment Installation Procedures
2.3.1 Cooling Requirements
Forced air cooling of the PMA7000M-S is not required. However the unit should be kept
away from heat producing sources (i.e. defrost or heater ducts, dropping resistors, heat
producing avionics) without adequate cooling air provided.
2.3.2 Mounting Requirements
The PMA7000M-S 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
Advisory Circular AC 43.13-2A. The unit may be mounted in any area where adequate
clearance 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.
NOTE: The mounting hole configuration for the PMA7000M-S is identical to the
PMA6000 series and KMA-24 Audio Selector Panels.
2.3.3 Mounting Rack Installation
Remove the unit from the mounting tray by unscrewing the 3/32" hex-head screw that is in
the center of the unit. Use caution to avoid hitting the photo-detector lens. Carefully slide
the unit free of the tray. 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 PMA7000M-S. 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 #440 screws, from the inside of the tray. Ensure that proper strain relief and chafing precautions are made during wiring and installation.
2.4 Cable Harness Wiring
Referring to the appropriate Appendix, assemble a wiring harness as required for the installation. 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 PS Engineering warranty.
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PMA7000M-S Series Audio Selector Panel and Intercom System
PS Engineering
Installation and Operator’s Manual
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 PMA7000M-S 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
PMA7000M-S 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 gyros, switching power supplies, etc.) However, installation combinations can occur where interference is possible. The PMA7000M-S 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
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 -01, -02 or -03), the existing 44 pin connector can be used for the bottom connector of the PMA7000M-S tray as is, providing it is
properly installed and wired. No other changes are required except for external marker
lights (see Section 3.7.2 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 PMA7000M-S tray.
2.4.3 Existing PMA6000 installations
In 28-Volt aircraft, the dropping resistor may be removed, however, the 2 Amp breaker
should be changed to 3 Amp. If both old unit is stereo (PMA6000S or PMA6000MS), no
rewiring is necessary unless additional features are added.
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PMA7000M-S Series Audio Selector Panel and Intercom System
PS Engineering
Installation and Operator’s Manual
2.4.3.1 Stereo PMA7000M-S installations into monaural PMA6000, PMA6000M.
Installations replacing PMA6000 or PMA6000M require re-wiring of the top connector to
accommodate the stereo configuration. See appendixes for detailed interconnect information.
2.4.4 Power
The PMA7000M-S-Series are 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 External 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. There are three typical configurations that can be used. Select the case that best fits the installation. Only the person
who presses their PTT switch will be heard over the radio. If the pilot and copilot both use
the PTT, the only 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 PMA7000M-S is in
the FAIL-SAFE mode.
CASE I: PTT is built into both pilot and copilot yokes.
CASE II: PTT is in pilot yoke only. This configuration requires a modified external PTT
switch plugged into the copilot's microphone jack. (See Appendix A). When the copilot's
PTT is pressed, the intercom switches the microphone audio from pilot to copilot mic.
CASE III: No built in PTT. This requires two built in PTTs to be installed, or modified
external PTT switches to be used. Modify external PTT as required (See Appendix A).
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 installation
manual.
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 depressing 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 PMA7000M-S has an automatic dimming of the pushbutton annunciator LEDs and
marker lamps controlled by a photocell. Control of the unit backlighting is through the air-
200-070-0006 Page 2-4 Rev. 6, Nov 98
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