PS Engineering PAC45 User Manual

PS Engineering
PAC45 Audio Selector Panel and Intercom System
Installation and Operator’s Manual
200-045-0000 Page 2-3 Rev. 7, May 2019
2.4 Cable Harness Wiring
Referring to the appropriate Appendix, assemble a wiring harness as required for the installa-
tion. All wires must be MIL-SPEC in accordance with current regulations. Two- and three-con-
ductor shielded wire must be used where indicated, and be MIL-C-27500 or equivalent specifica-
tion. 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 43.13-2B 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.
See Appendix C and D for intercom connection configurations. It is critical to the proper opera-
tion 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 controller end
only, and tie to the audio low inputs as shown.
2.4.1 Electrical Noise
Due to the variety and the high power of radio, equipment often found in today's aircraft, there
is a potential for both radiated and conducted noise interference.
The PAC45 power supply is specifically designed to reduce conducted electrical noise on the air-
craft power bus by at least 50dB. Although this is a large amount of attenuation, it may not elim-
inate all noise, particularly if the amplitude of noise is very high. 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 PAC45 was designed in a RFI hard-
ened chassis and has internal Electromagnetic Interference (EMI) filters on all inputs and out-
puts.
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 dia-
gram 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 the ground.
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 mi-
crophone jacks.
2.4.1.1 Music Input and Noise
PAC45 units utilize a differential ground input to help prevent noise from entering the audio sys-
tem. This feature is usually transparent to the installer; however, it is important that the appro-
priate music signal and ground connections are made directly to the dedicated music signal and
ground inputs on the PAC45. The power for IFE and audio controller should be a common bus.

PS Engineering PAC45 Specifications

General

Brand	PS Engineering
Model	PAC45
Category	Recording Equipment
Language	English