Ps-engineering PMA7000CAP Installation Manual User Manual download pdf (Page 11)

PS Engineering

PMA7000M-S Series Audio Selector Panel and Intercom System

Civil Air Patrol Version Installation and Operator’s Manual

200-072-0004 Page 2-4 Rev. 4, Sept. 2000

2.5.4 Power

The PMA7000M-S-Series is 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.

2.5.5 Radio 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 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 FAIL-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).

Additional capability can be added to the PMA7000MS for observer or additional transmit

stations. Contact PS Engineering for information

2.5.6 Transmit Interlock

Some communications transceivers use a transmit-interlock system. To fully utilize the Split

Mode feature, this function must be disabled. Consult that equipment manufacturer's installation

manual.

2.5.7 Required "Swap" Mode for Civil Air Patrol Versions

NOTE:

A SWAP switch is REQUIRED to access ALL of the CAP transceiver combinations

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 various transceiver combinations. In

the Com 1 or Com 2 position on the mic selector switch, the swap switch will change the

selected transceiver to the opposite unit. For instance, if the mic selector is in Com 1, and the

swap switch depressed, Com 1 is deselected and Com 2 selected.

In the PMA7000MS –CAP, the swap switch is active in the split mode. In the Com 1/2 mic

selector position, depressing the Swap switch will place the pilot on Com 2, and the

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Ps-engineering PMA7000CAP Installation Manual User Manual Page 11