PS Engineering PMA8000C Installation Manual - Manual (Page 10)

PS Engineering
PMA8000C Audio Selector Panel and Intercom System
Installation and Operator’s Manual
200-890-0303 Page 2-3 Rev. 3, May 2014
The shields can be daisy-chained together, and then connected to the ground lugs mounted on the back plate
shown in Appendix B.
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.
2.4.1.1 Music Inputs and Noise
PMA8000C units utilize a differential input to help prevent noise from entering the music system. This fea-
ture is usually transparent to the installer; however, it is important that the appropriate music signal and
ground connections are made directly to the dedicated music signal and ground inputs on the PMA8000C.
The power for IFE and audio panel should be a common bus.
If a music jack instead of a music source is installed for Music 1 or 2, we recommend grounding the jack to
airframe ground.
NOTE
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 GMA340 Installation
If the installation replaces a GMA340, no changes are necessary as long as the existing installation meets
the requirements. All existing functions of the GMA340 as well as all of the new capabilities afforded by
the PMA8000C will become instantly available. The PMA8000C does support 3 VHF COMs, or 2 VHF
COMs and HF radio, or other transceiver configuration.
Added capabilities include, IntelliVox®, DuTel™ duplex telephone, improved music fidelity and Soft
Mute™ and Karaoke™ muting modes, improved and more flexible music distribution control, internal re-
corder function, and additional unswitched audio inputs.
2.4.3 Power
The PMA8000C is compatible with both 14 and 28 Volt DC systems. A five (5) Amp circuit breaker is re-
quired for all installations. Power and ground wires should be #22 connected to J2 Pins 8 and 9. Connect
airframe ground to J2 Pin 10 and 11 only.
2.4.4 Communications Push-to-Talk
An important part of the installation is the PTT (Push-To-Talk) switches that allow the use of your aircraft
communications radio for transmissions. There are three typical configurations that can be used. Select the
case that best fits the installation. Only the person who presses their PTT switch will be heard over the ra-
dio. If the pilot and copilot both use the PTT, the only pilot position has access to the radio. The pilot posi-
tion will have PTT control regardless of the mic selector switch or copilot PTT when the PMA8000C is in
the
OFF /E MG mode.
CASE I: PTT is built into both pilot and copilot yokes.
CASE II: PTT is in pilot yoke only. This configuration requires a modified external PTT switch plugged
into the copilot's microphone jack. (See Appendix A). When the copilot's PTT is pressed, the intercom
switches the microphone audio from pilot to copilot mic.
CASE III: No built in PTT. This requires two built in PTTs to be installed, or modified external PTT
switches to be used. Modify external PTT as required. See Appendix A.
2.4.5 Audio Panel interface
The PMA8000C is designed to interface with standard aircraft avionics with 510
 receiver impedance. 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.