PS Engineering
PAC24 Series Audio Selector Panel and Intercom System
Installation and Operator’s Manual
200-240-0010
Page 3-2
Rev. 29, Sept. 2021
problem.
3.4
Communications Selection (2)
There are 10 pushbuttons associated with the communications transceivers. The lower buttons control
which transceiver is selected for transmit.
The PAC24 gives priority to the pilot’s PTT. If the copilot it transmitting, and the pilot presses his PTT, the
pilot’s microphone will be heard over the selected com transmitter.
The PAC24 has an automatic selector mode. Audio from the transceiver selected by the Xmit button is au-
tomatically heard in the headsets and speaker (if selected). You can check this function by switching from
C
OM
1 to C
OM
2 and watch the selected audio light on the selector change from COM 1 to COM 2. This
ensures the pilot will
always
hear the audio from the transceiver he is transmitting on.
When switching from C
OM
1 to C
OM
2, while C
OM
2 audio had been selected, Com 1 audio will continue
to be heard. This eliminates the pilot having to switch Com 1 audio back on, if desired.
When switching from C
OM
1 to C
OM
2 while Com 2 has NOT been selected, Com 1 audio will be switched
off. In essence, switching the mic selector will not effect the selection of Com receiver audio. This is true
of all transmitter selections.
NOTE
: The radio audio to the expansion unit is provided only by the audio panel connected. For example,
the expansion unit connected to the copilot audio panel will
ONLY
receive audio selected by the copilot.
The expansion unit connected to the pilot audio panel will
ONLY
receive audio selected by the pilot. Do
not use the expansion Mono input for radio. (11606 Pin 22).
3.4.1
Telephone Operation (S5 Switch 4 selected ON)
In a single installation, the intercom mode select switch determines who is on the phone:
ISO - pilot
CREW - pilot and copilot (passengers if IntelliPAX expansion NOT present)
ALL - pilot, copilot, passengers
In a standard dual installation, the pilot and copilot can select TEL mode independent of each other by
pressing their respective COM5 XMT button. The passengers are on the phone only when the pilot has se-
lected TEL (Com 5) mode and his switch is in the ALL position. The copilot cannot put the passengers on
the phone, and the passengers can only get on the phone when the pilot is on the phone. In an observer dual
installation, the crew box works like a single installation.
The observer is treated like a passenger, so he would be on the phone line when COM5 XMT is selected
and the intercom switch is in ALL mode. The observer cannot select telephone mode independently.
NOTE: Selecting the COM 5 –TEL– mode will disable pilot and copilot intercom, as the intercom circuit is
transferred to the telephone use. However, sidetone will be present.
3.4.2
Stuck Microphone Protection
The PAC24 has a function designed to prevent unintentional radio transmissions and blocked frequencies.
After 35 seconds of continuous PTT on any input, the PTT line is lifted, and will remain unkeyed until the
PTT input is recycled.
3.4.3
Swap Mode (Remote transfer of com transceivers)
With a yoke mounted, normally open, momentary switch, the pilot can change from the current Com trans-
ceiver another by depressing this switch. Activating the swap switch will select the next transceiver, cy-
cling from 1 to 2 to 3 etc.