PS Engineering
PMA8000 Series Audio Selector Panel and Intercom System
Installation and Operator’s Manual
200-890-0000
Page 2-2
Revision 9, June 2005
FHP 6-32 x ½" screws (475-632-0012). The audio selector panel must be supported at front and rear of the
mounting tray.
2.3.4 Audio Panel Tray and Connector Assembly
The rack connectors mate with two 44-pin connectors in the PMA8000. The connectors are a sub miniature
crimp-type, and require the use a hand crimp tool, from table below (or equiv.). The connectors are
mounted to the tray back plate with #4-40 screws (475-440-0007), from the inside of the tray. Ensure that
proper strain relief and chafing precautions are made during wiring and installation, using the cable clamp
(625-001-0002).
Manufacturer
Crimping
Tool Positioner Extraction
tool
AMP
601966-1 601966-6 91067-1
Daniels AFM8 K42
M24308-1
ITT-Cannon 995-0001-584 995-0001-739 91067-1
Table 1 Connector Pin crimping tools
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 PMA8000 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 connec-
tor, J2 pins 8 & 9, of the PMA8000 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 inter-
ference is possible. The PMA8000 was designed in a RFI hardened chassis and has internal Electromag-
netic 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.
The shields can be daisy-chained together, and then connected to a ground lug mounted on the corner of
the back plate.
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.
