PS Engineering
PMA450 Audio Selector Panel and Intercom System
Installation and Operator’s Manual
200-450-0000
Page 2-5
Rev. 6, Dec. 2015
back lighting system to work. The photocell mounted in the unit face will automatically adjust the intensity
of the push-button annunciator LEDs.
2.4.8
Unswitched inputs
J1, pins 31 (Unsw 1), 44 (Unsw 2) 29 (Unsw 3) and J2 pin 15 (Unsw 4) are unswitched, unmuted (by
transmitter keying), inputs.
These inputs are presented to the pilot and copilot regardless of the audio configuration, and will always
mute the crew entertainment inputs. These 510Ω inputs can be used for altimeter DH audio, GPS waypoint
audio, autopilot disconnect tones, or any other critical audio signal.
Unswitched #1 is always presented to the speaker, plus to the crew headphones, and is available to the pilot
in fail-safe (off) mode.
Unswitched 1 & 2 are always presented to the speaker, plus to the crew headphones.
*Unswitched 3 and 4 inputs are always presented to the crew headphones but presented to the aircraft
speaker
only
when the speaker is selected.
Unswitched
Input
Hear in
Fail Safe
Hear in
Crew Headset
Hear in SPR
Adjustable at installation
1
Yes
Yes
Yes
No
2
No
Yes
Yes
No
3
No
Yes
When SPR Selected
Yes
4
No
Yes
When SPR Selected
Yes
Table 2-3 Unswitched inputs
The audio low for unswitched #4 (J2, pin 15) should be connected to a convenient audio low. However, this
should NOT be connected to Music Low.
NOTE
Inputs 1 and 2 are fixed (1:1), and any audio level adjustments must be made at the input source.
Unswitched #3 and #4 can be adjusted at installation. Refer to Adjustments §2.7.
2.4.9
"Swap" Mode
When a momentary, normally open, push-button switch is connected between pin 20 on the J2 connector
and aircraft ground, the user can switch between Com 1 and 2 by depressing 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. The transfer of TX indication from Com 1 to Com 2 shows that the swap has
been initiated; there is no dedicated swap indicator.
2.4.9.1 Cell phone Sidetone
The PMA450 can provide cellular telephone sidetone (the user’s voice fed back to the headset). Some cell
phones provide sidetone, and may have poor audio quality if both sources are combined. The cell phone
sidetone is adjustable in the Bluetooth® operation screen
See §2.7
.
NOTE
Unauthorized use of unapproved cellular telephone devices in aircraft is subject to FCC enforcement ac-
tion, which may include a $10,000 fine per incident.
FCC Regulation 47 CFR § 22.925
Prohibition on airborne operation of cellular telephones
.
Cellular telephones installed in or carried aboard airplanes, balloons or any other type of aircraft must not
be operated while such aircraft are airborne (not touching the ground). When any aircraft leaves the ground,
all cellular telephones on board that aircraft must be turned off.
PS Engineering, Inc. does not endorse using unapproved cellular telephone equipment in flight, and takes
no responsibility for the user’s action.
PS Engineering does not guarantee compatibility with personal cellular telephones.