PS Engineering PAC24 Installation Manual - Manual (Page 15)

PS Engineering
PAC24 Series Audio Selector Panel and Intercom System
Installation and Operator’s Manual
200-240-0010 Page 2-8 Rev. 24, Dec. 2013
 For IRS, change SW2 1-2 to OFF, ON. NOTE: CVR cannot be used
2.3.4 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.
2.3.5 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.
2.3.6 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, shield-
ing 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
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 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