PS Engineering
PMA7000M-S Series Audio Selector Panel and Intercom System
Installation and Operator’s Manual
200-070-0006
Page 2-4
Rev. 6, Nov 98
2.4.3.1 Stereo PMA7000M-S installations into monaural PMA6000, PMA6000M.
Installations replacing PMA6000 or PMA6000M require re-wiring of the top connector to
accommodate the stereo configuration. See appendixes for detailed interconnect informa-
tion.
2.4.4 Power
The PMA7000M-S-Series are compatible with both 14 and 28 Volt DC systems. A two
(2) Amp circuit breaker is required for 14 VDC installations, and a three (3) Amp breaker
for 28 VDC aircraft. Power and ground wires must be a twisted #18 AWG pair. Connect
airframe power ground to J1 (bottom connector) Pin Z only. No dropping resistors are
required.
2.4.5 External 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 con-
figurations 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 PMA7000M-S 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 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).
2.4.6 Transmit Interlock
Some communications transceivers use a transmit-interlock system. To fully utilize the
Split Mode feature, this function must be disabled. Consult that manufacturer's installation
manual.
2.4.7 "Swap" Mode
When a momentary, normally open, push-button switch is connected between pin 10 on
the top connector and aircraft ground, the user can switch between Com 1 and 2 by de-
pressing this switch without having to turn the mic selector switch. This yoke-mounted
switch eliminates the need to remove your hands from the yoke to change transceivers.
2.4.8 Backlighting
The PMA7000M-S has an automatic dimming of the pushbutton annunciator LEDs and
marker lamps controlled by a photocell. Control of the unit backlighting is through the air-