PS Engineering PMA6000B - Manual (Page 11)

PS Engineering
PMA6000B Audio Selector Panel and Intercom System
Installation Manual
200-066-0200 Page 2-5 Rev 6, Feb. 2013
2.4.4 External 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 copilot position has access to the radio. The
pilot position will have PTT control regardless of the copilot when the PMA6000B is in the F
AIL - SAFE
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 mic 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 Transmit Interlock
Some communications transceivers use a transmit interlock system. In order to fully utilize the Split Mode
feature, this function must be disabled. Consult that manufacturer's installation manual.
2.4.6 Power
The PMA6000B-Series are compatible with both 13.8 and 28-Volt DC systems. A two (2) Amp circuit
breaker is required. Power and ground wires must be a twisted #22 AWG pair.
Included with this product is a power dropping resistor to be connected in series with the power input,
bottom connector, pin 43. This dropping resistor is supplied for 28-volt systems so that unnecessary heat
dissipation inside the PMA6000B can be avoided.
NOTICE: To reduce the amount of heat dissipated in the audio selector panel, when used in a 28
Volt aircraft, a 15 , 15 Watt dropping resistor (p/n 701-015-1501) must be installed in series
with the power input. This resistor should be mounted to aircraft structure to dissipate heat
2.4.7 "Swap" Mode
When a normally-open, momentary, push-button switch is connected between pin 29 on the connector and
aircraft ground, the user can switch between Com 1 and 2 by depressing this switch without having to
change the mic selector. This yoke mounted switch eliminates the need of removing your hands from the
yoke to change transceivers.
2.4.8 Backlighting
The PMA6000B has an automatic backlighting system controlled by a photo detector. Additional control
can be gained by the aircraft avionics dimmer control. Connect the dimmer control line to connector pin
41. The unit has an internal jumper to select between 14-volt and 28–volt electrical systems.
This installation provides the ability to bring the backlighting level to zero. If dimmer control is not used,
a constant low-level back light illumination has been established for nighttime viewing. The photocell
located in the center of the unit face will automatically adjust the backlight of the push-button lights.
2.4.8.1 Backlighting
As shipped from the factory, the PMA6000B is configured for 14V dimmer systems. For 28V dimmer
systems remove jumper J9.