PS Engineering PA50 - Manual (Page 7)

PS Engineering
PA50 Four-channel Audio Summing Amplifier
Installation and Operator’s Manual
200-150-0100 Page 2-2 October 2006
2.3.3 Connector Assembly
The rear of the PA50 contains a male DB25 connector. In the parts kit is a female shell with qty. 12 crimp
type pins. The appropriate crimper is Paladin PA1440. Ensure that proper strain relief and chafing precau-
tions are made during wiring and installation.
2.4 Cable Harness Wiring
Referring to the 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 solder-
ing technique must be used at all times. It is imperative that correct wire be used.
Refer to FAA Advisory Circular 43.13-2A (or later revision) 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.
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 audio signals are "bundled" with current carrying power
wires. Keep these cables physically separated.
2.4.2 Power (Pin 25)
The PA50-Series are compatible with both 14 and 28 Volt DC systems. A one (1) Amp circuit breaker is
required. Power and ground wires must be a twisted minimum #20 AWG pair. Connect airframe power
ground to Pin 13 only.
2.4.3 Unswitched Inputs (Pins 3, 4, 15, and 16)
Four 510 Ω unswitched inputs are provided for audio summing on pins 3, 4, 15, and 16 with respect to
(WRT) pin 18. These can be used to add audio capability such as TAWS, autopilot audio, etc, to an audio
panel that only has two inputs. The output is on Pin 14.
2.4.4 Output wiring
The output on Pin 14 (WRT Pin 18) of the PA50 is usually presented to the unswitched audio panel or in-
tercom input. It is critical to the proper operation of this system to have this connector wiring made in ac-
cordance with these diagrams. Use 2- and 3-conductor, MIL-spec cable as shown. Connect the shields at
one end only, and tie to the audio low inputs as shown.
2.5 Adjustments
The PA50 is factory adjusted to accommodate the typical requirements for most aircraft configurations.
The output volume can be adjusted by turning “VOL ADJ” clockwise to increase the volume or counter-
clockwise to decrease. The gain adjust affects all four inputs. See Appendix B for locations