PS Engineering PAC24 User manual

9800 Martel Road
Lenoir City, TN 37772
www.ps-engineering.com
PAC24
Audio Control Panel and Intercom System
Document P/N 200-240-0010
Revision 13, September 2007
PS Engineering, Inc. 2007 ©
Copyright Notice
Any reproduction or retransmittal of this publication, or any portion thereof, without the expressed written permission of PS En-
gineering, Inc. is strictly prohibited. For further information contact the Publications Manager at PS Engineering, Inc., 9800 Mar-
tel Road, Lenoir City, TN 37772. Phone [phone], email [email protected].
In certified aircraft, warranty is not valid unless this product is installed by an
Authorized PS Engineering dealer.

Table of Contents
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........................................................................................................................1-2
1.6 EQUIPMENT SUPPLIED ............................................................................................................1-3
1.7 EQUIPMENT REQUIRED BUT NOT SUPPLIED...................................................................1-4
1.8 LICENSE REQUIREMENTS ......................................................................................................1-4
SECTION II - INSTALLATION.......................................................................................................2-1
2.1 GENERAL INFORMATION.......................................................................................................2-1
2.1.1 SCOPE..........................................................................................................................................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 INTERNAL DIP SWITCH CONFIGURATION ......................................................................................2-1
2.3.3 MOUNTING REQUIREMENTS...........................................................................................................2-7
2.3.4 MOUNTING RACK INSTALLATION ..................................................................................................2-7
2.3.5 TRAY AND CONNECTOR ASSEMBLY ..............................................................................................2-7
2.4 CABLE HARNESS WIRING ...............................................................................................................2-7
2.4.1 NOISE ............................................................................................................................................2-7
2.4.2 EXISTING KMA 24H INSTALLATION.............................................................................................2-8
2.4.3 POWER...........................................................................................................................................2-8
2.4.4 COMMUNICATIONS PUSH-TO-TALK (SINGLE PANEL INSTALLATION)..............................................2-8
2.4.5 AUDIO PANEL INTERFACE..............................................................................................................2-8
2.4.6 TRANSMIT INTERLOCK...................................................................................................................2-9
2.4.7 "SWAP" MODE...............................................................................................................................2-9
2.4.8 BACKLIGHTING..............................................................................................................................2-9
2.4.9 UNSWITCHED INPUTS.....................................................................................................................2-9
2.4.10 PA MUTE (J3, PIN 8)...................................................................................................................2-9
2.4.11 PUBLIC ADDRESS (J3, PIN B) ......................................................................................................2-9
2.4.12 INTERCOM WIRING.......................................................................................................................2-9
2.4.13 ENTERTAINMENT INPUT (J3 PIN 7) ............................................................................................2-10
2.4.14 INTERCOM EXPANSION (J3, PINS 22, 23 AND A) ........................................................................2-10
2.4.15 PLAYBACK BUTTON INSTALLATION (PIN 2- OPTION 1 UNITS ONLY)..........................................2-10
2.5 ADJUSTMENTS ...............................................................................................................................2-11
2.6 COMMUNICATIONS ANTENNA INSTALLATION NOTES .................................................................2-11
2.7 WIRELESS TELECOMMUNICATIONS INTERFACE ..........................................................................2-11
2.8 PAC24 PIN ASSIGNMENTS.............................................................................................................2-13
2.9 POST INSTALLATION CHECKOUT..................................................................................................2-14
2.10 UNIT INSTALLATION ...................................................................................................................2-14
2.10.1 OPERATIONAL CHECKOUT.........................................................................................................2-14
2.11 INTERNAL RECORDER CHECKOUT (OPTIONAL UNITS ONLY)....................................................2-15
2.12 FINAL INSPECTION ......................................................................................................................2-15
SECTION III OPERATION ..............................................................................................................3-1
3.1 SCOPE............................................................................................................................................3-1
3.2 PAC24 CONTROLS..........................................................................................................................3-1
3.3 POWER SWITCH (3) (EMG-FAIL SAFE OPERATION).....................................................................3-1
3.3.1 SINGLE PANEL FAIL SAFE OPERATION...........................................................................................3-1
3.3.2 DUAL PANEL FAIL SAFE OPERATION.............................................................................................3-1
3.4 MICROPHONE SELECTOR (2) ..........................................................................................................3-2
3.4.1 TELEPHONE OPERATION ................................................................................................................3-2
3.4.2 STUCK MICROPHONE PROTECTION ................................................................................................3-2

PS Engineering
PAC24 Series Audio Selector Panel and Intercom System
Installation and Operator’s Manual
200-240-0010 Page ii Rev. 13, Sept. 2007
3.4.3 SWAP MODE (REMOTE TRANSFER OF COM TRANSCEIVERS) ...........................................................3-2
3.4.4 OBSERVER TRANSMIT SELECTION (PART NUMBER –0400 SERIES)..................................................3-2
3.5 RECEIVE AUDIO SELECTOR (1).......................................................................................................3-3
3.5.1 SPEAKER AMPLIFIER (4) ................................................................................................................3-3
3.5.2 KEY “CLICK”.................................................................................................................................3-3
3.6 SPLIT MODE ....................................................................................................................................3-3
3.6.1 SPLIT MODE, SINGLE PANEL..........................................................................................................3-3
3.6.2 SPLIT MODE, DUAL PANEL............................................................................................................3-4
3.6.3 SPLIT MODE, OBSERVER PANEL (-04XX) .....................................................................................3-4
3.7 INTERCOM OPERATION...................................................................................................................3-4
3.7.1 INTELLIVOX® VOX-SQUELCH.......................................................................................................3-4
3.7.2 VOLUME CONTROL (3) ..................................................................................................................3-5
3.7.3 INTERCOM MODES (5) ...................................................................................................................3-5
3.7.4 ENTERTAINMENT INPUT.................................................................................................................3-5
3.8 TELEPHONE MODE..........................................................................................................................3-6
3.9 INTERNAL RECORDER SYSTEM (OPTION 1 UNITS ONLY) .............................................................3-6
3.9.1 OPERATION....................................................................................................................................3-6
3.9.2 CONCURRENT MESSAGES ..............................................................................................................3-6
SECTION IV- WARRANTY AND SERVICE.................................................................................4-1
4.1 WARRANTY......................................................................................................................................4-1
4.2 FACTORY SERVICE..........................................................................................................................4-1
APPENDIX A – INSTALLATION DRAWING.................................................................................A
APPENDIX B SINGLE INTERCONNECT WIRING ...................................................................... B
APPENDIX B DUAL INTERCONNECT WIRING..........................................................................B
7.1 DUAL PAC24 WIRING WITH OBSERVER CONFIGURATION UNITS...................................................B
7.2 DUAL PAC24 WIRING WITH OBSERVER CONFIGURATION AND EXPANSION UNITS ........................B
APPENDIX C- INSTRUCTIONS FOR FAA FORM 337 AND CONTINUING
AIRWORTHINESS ...................................................................................................................................C
8.1 INSTRUCTIONS FOR FAA FORM 337, AUDIO PANELS......................................................................C
8.2 INSTRUCTIONS FOR CONTINUING AIRWORTHINESS, AUDIO PANELS..............................................C
APPENDIX D – RTCA DO160D (EUROCAE ED-14) ENVIRONMENTAL QUALIFICATION
FORM..........................................................................................................................................................D
Rev Date Change
9 March 2005 Clarified Expansion Grounding, also pin out diagram on 2-11
10 March 2006 Added cross reference tables for DIP switch settings 2.3.2
11 January 2007 Added Vertical Orientation Units

PS Engineering
PAC24 Series Audio Selector Panel and Intercom System
Installation and Operator’s Manual
200-240-0010 Page 1-1 Rev. 13, Sept. 2007
Section I GENERAL INFORMATION
1.1 INTRODUCTION
The PAC24 represents the finest in high-performance cockpit audio control and intercommunications. Us-
ing 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.
The PAC24 was designed to be a dual audio panel, offering convenience and utility for two-pilot crews, in
installations where a single panel is not practical.
The PAC24 –0500 is available where a vertical orientation would be appropriate.
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 PAC24.
1.2 SCOPE
This manual provides detailed installation and operation instructions for the PS Engineering PAC24-series
of Audio Selector Panel/Intercom Systems. This includes the following units:
Model Description Part Number
PAC24 Standard 050-240-0100
PAC24 Option 1, w/ Recorder 050-240-0200
PAC24 Observer 050-240-0400
PAC24 Observer Configuration with recorder 050-240-0401
PAC24 Standard, Vertical Orientation 050-240-0500
Where the functions are identical to all units, it will be referred to herein as a PAC24. Otherwise, the appli-
cable units will be specified.
1.3 EQUIPMENT DESCRIPTION
The PAC24-series is a state of the art audio isolation amplifier and audio selector that contains an auto-
matic voice activated (VOX) intercom system. It can switch up to five transceivers (Com 1, Com 2 Com 3
Com 4 and Com 5) and 4 receivers (Nav 1, Nav 2, AUX (or ADF in –0500) and MKR).
The Duplex Telephone mode allows the PAC24 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 may be prohibited by regulation.
PS Engineering is not responsible for unauthorized airborne use of cellular telephones.
For airborne use, the PAC24 must be interfaced with an approved system.
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 switch allows the user to listen to the
receiver(s) selected on the cabin speaker. Except for the unswitched inputs, all speaker audio is muted dur-
ing transmit.
Push button switches select the communication transceivers in use for the pilot and copilot position, and
allow radio transmission. In "Split Mode" the PAC24 has the ability to allow the pilot and copilot to oper-
ate different transceivers independently. The Com 5/TEL mode (selected at installation) allows the pilot to
use the audio panel for duplex operation, such as with aviation-specific cellular telephones.
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.

PS Engineering
PAC24 Series Audio Selector Panel and Intercom System
Installation and Operator’s Manual
200-240-0010 Page 1-2 Rev. 13, Sept. 2007
A voice activated (VOX) intercom is included in the PAC24. This system has PS Engineering’s exclusive
IntelliVox® circuitry that eliminates manual adjustments. The system contains six separate VOX mic cir-
cuits, and only opens the specific microphone channel in use.
The intercom system incorporates pilot isolate and crew modes, a monaural music input with "Soft Mute,"
and LED indicators transmit indications. Intercom control is through front panel-mounted knob and 3 po-
sition 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 con-
trol is further adjustable through screwdriver access in the top of the unit. Intercom squelch is automatic.
The PAC24 is form fit and function compatible with the King Radio KMA24H, part number 066-1055-71,
and may be compatible with 066-1055-70.
1.4 APPROVAL BASIS -
FAA-TSO Approval.
The PAC24 Audio Selector Panels are FAA approved under TSO C50c (Audio Amplifiers). In addition,
the PAC24 is JAA-JTSO approved under LBA.N-O.10.510/003JTSO.
All systems comply with relevant portions of EUROCAE ED-14C/DO-160D (Environmental Conditions and Test
Procedures for Airborne Equipment), ED12B/DO-178B (Software Considerations for Airborne Equipment) and ED-
18/DO-214 (Audio Systems Characteristics and Minimum Operational Performance Standards for Aircraft Audio Sys-
tems).
NOTE: The recorder contained in Option 1 is not TSO-approved, and the installer must determine the relevant ap-
proval basis prior to installation. Contact PS Engineering for information regarding FAA approval.
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 opera-
tion.
1.5 SPECIFICATIONS TSO COMPLIANCE
Audio Selector/Intercom: C50c, Class A
APPLICABLE DOCUMENTS: RTCA/DO-214
RTCA/DO-160D
RTCA/DO-178B
ENVIRONMENTAL Qualifications: B1ZCABSRXXXXXXZBBBATMXXE2XXX
Temperature Range:
Operating:
Storage:
-20ºC to +55ºC with short term operating at +70°C
-55ºC to +85ºC
Altitude: Up to 50,000 feet in a 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) behind panel
WEIGHT (With Rack & Connectors): 1.5 lb. (0.54 kg)

PS Engineering
PAC24 Series Audio Selector Panel and Intercom System
Installation and Operator’s Manual
200-240-0010 Page 1-3 Rev. 13, Sept. 2007
Specifications, Continued.
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: 10
(Com 1, Com 2, Com 3, Com 4, Com 5, Nav 1,
Nav 2, ADF, DME, MKR)
Unswitched Inputs: 2
(examples: GPS WPT, Value, Autopilot Discon-
nect, Altimeter DH)
Transmitter Selections:5
(Com 1, Com 2, Com 3 Com 4, Com 5)
Speaker Impedance:4 – 8 Ω
Headphone Impedance: 150 – 1000 Ω
Headphone Output: 38 mW each headset, no clipping <1% THD
120 mW each headset with < 10% THD into
150Ω
Microphone Impedance: 150 - 600 Ω
Intercom Specifications
Intercom Positions: Minimum of 5 places (with individual IntelliVox® cir-
cuits)
Music Input: 1 (Monaural)
Music Muting: >-30 dB "Soft Mute" when Com or intercom active.
Distortion: <1% THD @ 38 mW into 150Ω
<10% THD @ 120mW into 150 Ω
Mic Freq. Response, 3 dB: 300 Hz - 6000 Hz
Music Freq. Response, 3 dB: 100 Hz - 18kHz
1.6 EQUIPMENT SUPPLIED
1 ea. of the following units:
Model Description Part Number
PAC24 PAC24 Audio Control Panel with intercom 050-240-0100
PAC24 Option 1 PAC24 Audio Control Panel with intercom and digital recorder, 050-240-0200
PAC24 Observer PAC24 Audio Control Panel for Observer installation 050-240-0400
PAC24 Observer Option 1 PAC24 Audio Control Panel for Observer with recorder 050-240-0401
PAC24 Vertical PAC24 Audio Control Panel with intercom, Vertical Orientation 050-240-0500

PS Engineering
PAC24 Series Audio Selector Panel and Intercom System
Installation and Operator’s Manual
200-240-0010 Page 1-4 Rev. 13, Sept. 2007
PAC24 Installation Kit: 250-291-0000
Description Quantity Part
Number
PAC24 installation rack assembly 1 475-240-0040
Molex Connector Shell w/key, 50 pin, key 17/18 1 120-425-5002
Gold Plated Crimp Pins 50 425-001-0002
4 40 X 7/16 screw w/nylon patch 4 475-440-0009
Grounding bar 1 430-007-0001
6-32 X 3/4 pan head Phillips screw 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” Flat head Phillips screw 6 475-632-0012
#6-32 Clip Nut 6 475-630-0002
Parts identification sheet 1 002-250-0240
1.7 EQUIPMENT REQUIRED BUT NOT SUPPLIED
a) Circuit Breaker: 1 ea. 3 amp
b) Cockpit Speaker, 4 Ωrecommended
c) Cabin or External Speaker 4 Ωrecommended
d) Headphone Jacks (as required)
e) Microphone Jacks (as required)
f) Headphones, 150 Ωas required
g) Microphones, as required
h) Interconnect Wiring
1.8 LICENSE REQUIREMENTS
None

PS Engineering
PAC24 Series Audio Selector Panel and Intercom System
Installation and Operator’s Manual
200-240-0010 Page 2-1 Rev. 13, Sept. 2007
Section II - Installation
2.1 GENERAL INFORMATION
2.1.1 SCOPE
This section provides detailed installation and interconnect instructions for the PS Engineering PAC24-
Series Audio Control Panel/Intercom System.
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: The PAC24 requires specialized knowledge and tools for an effective installation. An appropri-
ately 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 au-
thorized PS Engineering, Incorporated dealer. Failure to follow any of the installation instructions, or in-
stallation by a non-certified individual or agency will void the warranty, and may result in an unairworthy
installation.
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 com-
ponents 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 ac-
cessories shows any sign of external shipping damage, contact PS Engineering to arrange for a replace-
ment. 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.
2.3 Equipment Installation Procedures
2.3.1 Cooling Requirements
Forced air cooling of the PAC24 is not required. However the unit should be kept away from heat produc-
ing sources (i.e. defrost or heater ducts, dropping resistors, heat producing avionics) without adequate cool-
ing air provided. Outside, ram air cooling of the unit is not permitted, and may result in damage.
2.3.2 Internal DIP Switch Configuration
The tables below describe the various internal switch selections.
The PAC24 can be easily configured for many different applications. This includes dual audio panel
installations. In a single installation, no action is required. In dual installations, place the DIP witches into
the proper position to configure the PAC24 as the pilot, or copilot panel. By designating a pilot or copilot
panel, the aircraft commander, or pilot, will have priority for transmissions and intercom mode selection.
Note:
Bold=Default settings (as shipped from factory)
Units are shipped as single unit configuration, 28V lighting.

PS Engineering
PAC24 Series Audio Selector Panel and Intercom System
Installation and Operator’s Manual
200-240-0010 Page 2-2 Rev. 13, Sept. 2007
2.3.2.1 Single/Dual configuration
Switch S5
2 OFF ON ON
3 OFF
Single
PAC24
Installation OFF
Pilot unit –Dual
Installation ON
Copilot
unit –Dual
Installation
Single System/Pilot Copilot Panel
J4 ON (installed) J4 OFF (Removed)
J5 Jumper Pins 1 & 2 J5 Jumper Pins 2 &3
S2
S3
S5
S4
4 3 2 1 4321
4 3 2 1 4321

PS Engineering
PAC24 Series Audio Selector Panel and Intercom System
Installation and Operator’s Manual
200-240-0010 Page 2-3 Rev. 13, Sept. 2007
2.3.2.2 Pass 3 / Expansion – J3, pin a configuration
As shipped, the PAC24 is 5-place intercom, and the ability to convert the system from a 5-place intercom
to use an expansion unit that will allow up to 8 places on the intercom per audio panel.
Switch S2
3 ON OFF
4 OFF Pass 3 Mic Input ON Expansion Power
out
2.3.2.3 Pass 1 / Expansion – J3, pin 22 configuration
Switch S3
1 ON OFF
2 OFF Pass 1 mic input ON Expansion audio
input
2.3.2.4 Pass 2 / Expansion - J3, pin 23 configuration
Switch S3
3 ON OFF
4 OFF Pass 2 mic input ON Expansion audio
output
2.3.2.5 CVR / IRS Control – J3, pin 2 configuration
PAC24 units can be equipped with an optional Intercom Recording System (IRS, P/N –0200, -0401),
which will store up to 60 seconds of radio traffic (on the transceiver selected for transmit). The playback
control is a normally open switch connected to ground, which triggers the stored audio.
Internal Recording System units are incompatible with the standard Cockpit Voice Recorder output
J5 J4
Pin 1

PS Engineering
PAC24 Series Audio Selector Panel and Intercom System
Installation and Operator’s Manual
200-240-0010 Page 2-4 Rev. 13, Sept. 2007
Switch S2
1 ON OFF
2 OFF CVR Output ON IRS Playback Input
2.3.2.6 Backlighting / Swap – J3, pin 18 configuration
The installer has the option of implementing PS Engineering’s patented “Swap” function, which allows the
pilot to switch between Com 1 and Com 2 with an external switch. The Swap command is controlled
through the unused backlight input, and selected by the internal DIP switch.
Switch S4
1 ON OFF
2 OFF 14 V lighting
control ON Swap switch
2.3.2.7 Backlighting / Swap – J3, pin U configuration
Switch S4
3 ON OFF
4 OFF 28 V lighting
control ON Swap switch
2.3.2.8 Backlight 14/28V
Switc
h 14 V 28V
1 On
Off
2 Off
On
3 Off
On
4 On
Off
14 V Aircraft 28 V aircraft
Pin 18= 14 V input Pin 18=Swap
Pin U=Swap Pin U =28 V input
2.3.2.9 Expansion Mode / Telephone S5 configuration
Switch S5
1 On Expansion Unit Present (11606 installed)
4 On Duplex Telephone mode for Com 5
NOTE: Set both audio panels the same in a dual installation

PS Engineering
PAC24 Series Audio Selector Panel and Intercom System
Installation and Operator’s Manual
200-240-0010 Page 2-5 Rev. 13, Sept. 2007
2.3.2.10 Observer Installation Configuration (S5)
When the Observer versions are used (Part Number 050-240-0400, -0401, -0403, -0404) the cockpit unit is
configured as “Pilot” and the Observer station is configured as “Copilot.”
Switch S5
2 ON ON
3 OFF
Cockpit unit –
Observer Installa-
tion ON
Observer unit –
Installation
Switch S3
1 OFF
2 ON Expansion In
enabled
3 OFF
4 ON Expansion Out
enabled
Switch S2
3 ON
4 OFF Pass Input
In an observer unit, jumpers J4 and J5 should be configured like a copilot's unit in dual installation.
2.3.2.11 DIP Switch Cross reference.
Single Installation- 28 Volt Aircraft Single panel with Expansion - 28 Volt
Aircraft
SW2 SW3 SW4 SW5 SW2 SW3 SW4 SW5
1 ON ON OFF OFF 1OFF OFF OFF ON
2 OFF OFF ON OFF 2ON ON ON OFF
3 ON ON ON OFF 3OFF OFF ON OFF
4 OFF OFF OFF See
notes 4ON ON OFF See notes
J4- On/ J5- Pins 1 & 2 J4- On/ J5- Pins 1 & 2
Table 2-1 Single Audio Panel DIP switch settings

PS Engineering
PAC24 Series Audio Selector Panel and Intercom System
Installation and Operator’s Manual
200-240-0010 Page 2-6 Rev. 13, Sept. 2007
Dual PAC24 - Pilot Panel- 28 Volt Aircraft Dual PAC24- Copilot Panel- 28 Volt Aircraft
SW2 SW3 SW4 SW5 SW2 SW3 SW4 SW5
1 ON ON OFF OFF 1 ON ON OFF OFF
2 OFF OFF ON ON 2 OFF OFF ON ON
3 ON ON ON OFF 3 ON ON ON ON
4 OFF OFF OFF See
notes 4 OFF OFF OFF See
notes
J4- On/ J5- Pins 1 & 2 J4- Off J5- Pins 2 & 3
Table 2-2 Dual Audio Panel DIP Switch Settings without expansion
Dual PAC24 with Expansion- Pilot Panel- 28
Volt Aircraft Dual PAC24 with Expansion- Copilot Panel- 28 Volt Aircraft
SW2 SW3 SW4 SW5 SW2 SW3 SW4 SW5
1 ON OFF OFF ON 1 ON OFF OFF ON
2 OFF ON ON ON 2 OFF ON ON ON
3 OFF OFF ON OFF 3 OFF OFF ON ON
4 ON ON OFF See
notes 4 ON ON OFF See notes
J4- On/ J5- Pins 1 & 2 J4- Off/ J5- Pins 2 & 3
Table 2-3 Dual Audio Panel DIP Switch Settings with expansion
Dual PAC24 Observer- Cockpit
Panel- 28 Volt Aircraft Dual PAC24 Observer- Observer Panel- 28 Volt Aircraft
SW2 SW3 SW4 SW5 SW2 SW3 SW4 SW5
1 ON OFF OFF OFF 1 ON ON OFF OFF
2 OFF ON ON ON 2 OFF OFF ON ON
3 ON OFF ON OFF 3 ON ON ON ON
4 OFF ON OFF
See
notes 4 OFF OFF OFF See notes
J4 - On/ J5- Pins 1 & 2 J4 - Off/ J5- Pins 2 & 3
Table 2-4 Dual Audio Panel with Observer Function, DIP switch settings
Dual PAC24 Observer w Expansion-
Cockpit Panel- 28 Volt Aircraft Dual PAC24 Observer w Expansion- Ob- server Panel- 28 Volt Aircraft
SW2 SW3 SW4 SW5 SW2 SW3 SW4 SW5
1 ON OFF OFF ON 1 ON OFF OFF ON
2 OFF ON ON ON 2 OFF ON ON ON
3 OFF OFF ON OFF 3 OFF OFF ON ON
4 ON ON OFF See
notes 4 ON ON OFF See notes
J4- On/ J5- Pins 1 & 2 J4- Off/ J5- Pins 2 & 3
Table 2-5 Dual Audio Panel with observer and with Expansion
General Notes
• If telephone is connected, turn SW5-4 to ON for all panels. Otherwise set it to OFF
• For 14V aircraft, change SW4 1-4 to ON, OFF, OFF, ON
• For CVR output, change SW2 1-2 to ON, OFF. NOTE: IRS cannot be used
• For IRS, change SW2 1-2 to OFF, ON. NOTE: CVR cannot be used

PS Engineering
PAC24 Series Audio Selector Panel and Intercom System
Installation and Operator’s Manual
200-240-0010 Page 2-7 Rev. 13, Sept. 2007
2.3.3 Mounting Requirements
The PAC24 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 out-
puts, such as DME or transponders.
NOTE: The mounting hole configuration for the PAC24 is identical to the
KMA-24H -71 Audio Selector Panels.
2.3.4 Mounting Rack Installation
Remove the unit from the mounting tray by unscrewing the 3/32" hex-head screw that is between the RCV
and XMT legends. 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 clip nuts (475-630-0002),
and six FHP 6-32 x ½" screws (475-632-0012). The audio selector panel must be supported at front and
rear of the mounting tray.
2.3.5 Tray and Connector Assembly
The unit connector mates directly with the circuit board in the PAC24. The connector is a Molex crimp-
type, and requires the use of a Molex hand crimp tool, EDP P/N 11-01-0203, CR6115B (or equiv.). The
connector is mounted to the unit tray with #4-40 screws (475-440-0009), from the inside of the tray. En-
sure that proper strain relief and chafing precautions are made during wiring and installation, using the
cable clamp (625-001-0002). Secure the ground bar (430-630-0002), if desired using, #6-32 nuts (475-632-
0003) and #6-32 lock nuts (475-632-0004).
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.
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 PAC24 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 25, of the PAC24 for the power supply to work in its designed regulation. Otherwise, it can-
not 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 inter-
ference is possible. The PAC24 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).Under no
circumstances combine a microphone and headphone wiring into the same shielded bundle. Always use a
2- or 3-conductor, shield wire as shown on the installation wiring diagram.

PS Engineering
PAC24 Series Audio Selector Panel and Intercom System
Installation and Operator’s Manual
200-240-0010 Page 2-8 Rev. 13, Sept. 2007
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.
Adding a high-performance audio control system, particularly in conjunction with high-performance active
noise canceling headsets, cannot improve on older avionics that were designed for cabin-speaker use. PS
Engineering makes no claim that the audio panel will provide a noise-free audio quality under all installa-
tion conditions, particularly with older avionics.
2.4.2 Existing KMA 24H Installation
If the installation replaces a KMA-24H (series –71), and it is properly installed and wired, no other
changes are required except for removal of the keying pin. Other options not present in the KMA24H,
such as entertainment or “Swap” may require additional wiring. Speaker Power (J3, pin 7) is not required.
NOTE:
Many installation use external switching to provide crewmember isolation. These can usually be
eliminated. See below for details.
2.4.2.1 Single KMA24H -71 Installation
If the switch, labeled Isolate/Normal/Private is installed, the Primary/Secondary headphone switch should
be maintained. However, the connection to P241, Pins 21, 24, and Y should be removed.
2.4.2.2 Dual KMA24H -71 Installation
In a dual KMA24H-71 installation, we recommend that the ISO/Normal/Private switches be removed.
These switches apply a ground to logic inside the KMA24H.
THE CONNECTIONS BETWEEN THE AUDIO PANELS MUST BE LEFT INTACT. This includes Pins
V to V (Key Enable), 21 to 24 (Isolate /Isolate 22) and Y to Y (Private). PS Engineering uses these lines
for data bus communications between panels.
2.4.3 Power
The PAC24-Series are compatible with both 14 and 28 Volt DC systems. A three (3) Amp breaker is re-
quired. Power and ground wires must be a #18 AWG pair. Connect airframe power ground to J3 Pin 25
only. No dropping resistors are required.
2.4.4 Communications Push-to-Talk (single panel installation)
Unless the system is in split mode, only the person who presses their transmit 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 PAC24
is in the OFF/EMG mode.
2.4.4.1 Communications Push-to-Talk (Dual Panel Installation)
The PAC24 automatically senses if the other audio panel is transmitting. If communications transceivers
selected for transmit are different (Com 1 pilot, Com 3 copilot), both panels will allow simultaneous, dual
transmission (split mode). If the same radio has been selected for transmit on both audio panels, the pilot
mic will have priority, and the copilot will not transmit.
2.4.5 Audio Panel interface
The PAC24 is designed to interface with standard aircraft avionics, and presents a 500Ωreceiver imped-
ance. For best results, a twisted-shielded cable is recommended from the avionics audio source to the audio
panel, with the shield grounded at the audio panel end.
NOTE

PS Engineering
PAC24 Series Audio Selector Panel and Intercom System
Installation and Operator’s Manual
200-240-0010 Page 2-9 Rev. 13, Sept. 2007
Some avionics do not provide a separate audio low, and may introduce additional electrical noise into the
system. For best results, connect the audio low from the audio panel to the radio ground, using one conduc-
tor of the twisted-shielded cable.
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 U (14 V) or 18 (28V
lighting) on the unit connector and aircraft ground, the user can switch from Com 1 to 2 to 3 etc. 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 controls to change transceivers.
NOTE: Swap mode is active if the proper DIP switch selection is made internally to the unit.
2.4.8 Backlighting
The PAC24 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 dim-
mer control line to J3 pin 18 for 14-volt systems, and to J3 pin U for 28-volt systems. Pin 17 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 18 or U (depending on system voltage) must be tied to power (J3, pin 25) for
the back lighting system to work. The photocell mounted in the unit face will automatically adjust the in-
tensity of the push-button annunciator LEDs.
2.4.9 Unswitched inputs
J3, pin 10 is the unswitched input number 1 and J3 pin 14 is unswitched input 2. These inputs are presented
to the pilot and copilot regardless of the audio configuration, and will always mute the entertainment in-
puts. These 510Ωinputs can be used for altimeter DH audio, GPS waypoint audio, autopilot disconnect
tones, air-to-ground (Flitefone) telephone ringer or any other critical audio signal.
2.4.10 PA Mute (J3, Pin 8)
Pin 18 of J3 is a TTL logic output that is pulled low during PTT operation. This serves as an input to exter-
nal public address system to prevent feedback during transmissions.
2.4.11 Public Address (J3, Pin B)
When the Speaker mode switch is in the PA mode, and the pilot’s PTT is activated, his voice is heard over
the PA speaker output on J3, Pin B. The copilot can continue to use the selected com.
NOTE: Connecting two audio panels to a single speaker for cockpit or cabin ad-
dress can result in weak and distorted audio.
2.4.12 Intercom wiring
See Appendices for intercom 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.
2.4.12.1 Push to talk intercom
The PAC24 can be used as an IntelliVox® intercom, or, as a keyed intercom. Switching J3 pin W to
ground will inhibit the IntelliVox® and the intercom squelch will not open until the ICS PTT switch is
activated.

PS Engineering
PAC24 Series Audio Selector Panel and Intercom System
Installation and Operator’s Manual
200-240-0010 Page 2-10 Rev. 13, Sept. 2007
The following pins are used to control the intercom when PTT ICS is desired. Pin 11 must be grounded
through a momentary switch for the pilot to talk on the intercom (with W also grounded). Pin M must be
grounded through a momentary switch for the copilot to talk on the intercom (with W also grounded).
2.4.13 Entertainment Input (J3 Pin 7)
If music or entertainment is desired, a monaural input can be applied to Pin 7 of J3.
NOTE: Use the low level output of any entertainment device to connect to the audio
panel. Maximum signal level is 2 VAC p-p.
DO NOT use a speaker-level output, this will cause internal damage in the audio
panel.
PS Engineering offers an aviation Compact Disk player, the PCD7100 (Part Number 11952), designed to
interface with the audio panel.
All entertainment devices must be switched off for both takeoff and landing.
2.4.13.1 Entertainment distribution
The entertainment source provides music for all intercom copilot positions. In ISO, it is removed from the
pilot. The PAC24-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 some entertainment equipment can cause undesired
interference 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, immedi-
ately switch off the entertainment devices.
All entertainment devices must be switched off for both takeoff and landing.
2.4.13.2 Entertainment inhibit
The music input to the PAC24 uses the existing Speaker Power input from the KMA24-71. This pin should
be removed even if music is not desired. However, if avionics power remains on Pin 7, there is the possi-
bility of power ripple entering the system. The Music input can be deactivated from the front panel by
pressing the NAV 1 and AUX (DME in –0500) buttons for at least 3 seconds. The audio panel will then
ignore any signal on this input, until the Music Off mode is toggled again.
2.4.14 Intercom expansion (J3, Pins 22, 23 and a)
The PAC24 contains a five-place intercom (pilot, copilot and three passengers). In applications where more
intercom positions are needed, PS Engineering can provide intercom expansion units, such as the Intelli-
PAX, part number 11606, 11606R, etc. These can add up to six additional stereo intercom stations, plus
independent stereo music input. Interface to the expansion unit is through, pins 22 (audio input from ex-
pansion unit), 23 (audio output to expansion unit) and a (9 VDC expansion power).
These pins are shared with the microphone inputs; therefore the internal DIP switched must be correctly
configured (see above).
2.4.15 CVR Output/Playback button Installation (Pin 2- Option 1 units only)
As shipped from the factory, the PAC 24 has a CVR output on Pin 2, J3. In option 1 units (-0200 & -0401)
this output must be converted to a digital logic input by configuring the DIP switch (see 2.3.2.5).
To activate the Recording System playback, a momentary push button switch is required. This switch can
be located anywhere in cockpit convenient to the pilot's reach. The normally open switch must be con-

PS Engineering
PAC24 Series Audio Selector Panel and Intercom System
Installation and Operator’s Manual
200-240-0010 Page 2-11 Rev. 13, Sept. 2007
nected to pin 2 of J3 of the PAC24, and ground. This pin is shared with the CVR output; therefore the in-
ternal DIP switched must be correctly configured (see above).
2.5 Adjustments
The PAC24 is factory adjusted to accommodate the typical requirements for most aircraft configurations.
There are two adjustments however, that will allow the installer to tailor the volume controls to suit spe-
cific functions.
Figure 2-1- PAC24 Adjustments
2.6 Communications Antenna Installation Notes
For best results while in Dual installations or Split Mode (two communicates transceivers active at the same time), we
recommend that the one VHF communications antenna is located on top of the aircraft while the other communications
antenna is installed 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 together. PS Engineering makes no expressed or implied war-
ranties regarding the suitability of the PAC24 in Dual or Split Mode.
2.7 Wireless telecommunications interface
The PAC24 has interface capability with units such as the AirCell Guardian. It is the user’s responsibility to determine
the appropriate legal use of the equipment, and provide the equipment and services.
As installed in the standard configuration, the PAC24 Com 5 function operates conventionally. Pushing the Com 5
Xmt button places the receive audio from Com 5 in the headset and applies the pilot or copilot microphone to the Com
5 when the appropriate PTT is activated.
If telephone mode is selected by the internal DIP switch the PAC24 is forced into Com 5-Duplex mode. This mode is
designed to operate with telecommunications systems, such as the AirCell AGM.01. Intercom Audio streams are pro-
vided to the COM 5 output, the PTT for Com 5 is inactive, and audio from Com 5 is presented to the headset. This
allows a telephone-like audio interface. The COM 5 input and output is compatible with aviation radios.
In a DUAL Audio Panel installation, the telephone mic audio input should be connected to the PILOT COM 5 Mic
output (J3 pin only).
PS Engineering makes no expressed or implied warranty that the equipment will be compatible with any devices other
than AirCell.
PA Volume
Master Volume

PS Engineering
PAC24 Series Audio Selector Panel and Intercom System
Installation and Operator’s Manual
200-240-0010 Page 2-12 Rev. 13, Sept. 2007
Unauthorized use of cellular telephone devices in aircraft is subject to FCC enforcement action,
which may include a $10,000 fine per incident. PS Engineering, Inc. does not endorse using unap-
proved cellular telephone equipment in flight, and takes no responsibility for the user’s action.

PS Engineering
PAC24 Series Audio Selector Panel and Intercom System
Installation and Operator’s Manual
200-240-0010 Page 2-13 Rev. 13, Sept. 2007
2.8 PAC24 Pin assignments
PA Speaker
Entertainment in
Pilot Mic Key
Com 3 Mic Key
Com 4 Mic Key
Copilot Mic Audio Hi
Com 3 Audio
Com 2 Audio
Unswitched Audio In #1
Com 4 Audio
Com 1 Mic Key
Nav 2 Audio
Marker Audio
Com 2 Mic Key
Com 4 Mic Audio
Light Lo
14 V Light Hi
PA Mute
Speaker Lo
Aircraft Ground
Pass 2 Mic Audio Hi
SDA
Cockpit Spkr Out
Com 5 Mic Audio
Pilot Headphones
Com 3 Mic Audio
SCL
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
J3 Connector
PAX out ICS Cross Tie 2
Com 1 Mic Aud
Pilot ICS PTT
CVR Output
28 V lights Hi
23
24
25
a
b
c
DME Audio*
Unswitched Audio In #2
Pass 3 Mic Audio Hi
PAX IN- ICS X tie 1
11-33 Aircraft Power
Com 2 Mic Audio
Com 5 Mic Key
ADF Audio
Nav 1 Audio
Com 1 Audio
ICS Key
Copilot Mic Key
Pilot Mic Audio Hi
Pass 1 Mic Audio Hi
Copilot/Pass phones
Audio Low
Copilot ICS PTT
*No Connecttion (-0500)