0
G R O U N D
MAIN GND
K E Y I N G L I N E
FIGURE 2-2
Pinout Diagram for 50 pin, 37 pin, and 15 pin “D” connectors
2.9
PTT CONNECTIONS
The Pilot, Co-pilot and rear microphones require a PTT (Push To Talk) button or switch to
key the transceivers as required. If a Hand-held microphone is used, tie the PTT button to
the appropriate key line. If the Microphone is incorporated into the Headset. An external
Switch ie/ the cyclic switch, will be required to Key the transmitter. Any audio received by
the Pilot, Co-pilot or Rear microphones without the PTT keyed, will pass through the
intercom.
The Pilot, Co-pilot, and Transceivers are keyed by applying Ground to any one of the
appropriate key lines listed in Table 2-1 (50 pin “D”).
See also connection diagram Figure 2-3.
2 . 1 0
MAIN POWER + 28VDC
The main power + 28VDC ( 20%) is connected to pin 17 of the 50 pin (lower)
“D”connector. As previously indicated, this connection should be made with #22 AWG
wire. See Table 2-l (50 pin "D”). See also connection diagram Figure 2-3.
2.11
DIR AUDIO IN
The DIR audio input is an input source which is connected directly to the headset amplifiers,
and is not affected by any of the front panel control settings. This input is typically used for
audible warning system tones or other signals which must be audible at all times. The
output level is adjustable only by the potentiometer on the left side of the unit.
See Figure 3-2.
2-3
