PS Engineering PMA8000B Installation Manual - Manual (Page 10)

PS Engineering
PMA8000B Audio Selector Panel and Intercom System
Installation and Operator’s Manual
200-890-0100 Page 2-3 Rev. 13, Dec. 2009
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
PMA8000B units above Serial Number J01861 utilize a differential input to help prevent noise from e n-
tering the music system. This feature 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 PMA8000B. 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 ac-
tive 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 in-
stallation 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 PMA8000B will become instantly available. Be advised, the PMA8000B does not support 3 VHF
Coms, however. The PMA8000B handles two COM transceivers and a full-duplex cellular/satellite tel e-
phone.
Added capabilities include, IntelliVox®, DuTel™ duplex telephone, improved musi c fidelity and Soft
Mute™ and Karaoke™ muting modes, improved and more flexible music distribution control, internal
recorder function, and additional unswitched audio inputs.
2.4.3 Power
The PMA8000B is compatible with both 14 and 28 Volt DC systems. A five (5) Amp circuit breaker is
required for all installations. Power and ground wires should be #22 connected to J2 Pins 8 and 9. Con-
nect airframe ground to J2 Pin 10 and 11 only. No dropping resistors are required.
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 air-
craft 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 radio. If the pilot and copilot both use the PTT, the only pilot position has access to the radio.
The pilot position will have PTT control regardless of the mic selector switch or copilot PTT when the
PMA8000B 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 PMA8000B is designed to interface with standard aircraft avionics, and presents a 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.