PS Engineering
PMA7000BT Series Audio Selector Panel and Intercom System
Installation and Operator’s Manual
200-780-0204
Page 2-5
Rev. 1, July 2015
2.5.4
Audio Panel interface
The PMA7000BT is designed to interface with standard aircraft avionics, and presents a 500
receiver
impedance. For best results, a twisted-shielded cable is recommended from the avionics audio source to the
audio panel, with the shield grounded at the audio panel end.
Some avionics do not provide a separate audio low, and may introduce additional electrical noise into the
system. For best results, connect the audio low from the audio panel to the radio ground, using one conduc-
tor of the twisted-shielded cable.
2.5.4.1
Speaker Load
The PMA7000-series contains a speaker amplifier. Some units with internal speaker amplifiers, such as the
King Radio KX170-series, require a resistive load to prevent damage if their speaker amplifier is not used.
Connect the speaker output from the unit to the load input on the PMA7000BT (J1, pins 19 and L, 16 and
M. The speaker load is 16
, 3W.
2.5.4.2
Fail Safe Connection
The PMA7000BT connects the pilot microphone and headphone directly to COM 1 input when power is
removed. The headphone failsafe is the RIGHT channel, connected to the TIP of the headphone jack, to be
compatible with monaural headphones. Unswitched input #1 (Bottom Connector pin T) is also provided to
the pilot headset, right channel, in fail-safe.
NOTE: The pilot headphone MUST be wired in accordance with Appendix C, Bottom connector Pin 3 to
Pilot headphone tip (right) to ensure proper failsafe operation. Verify failsafe operation in accordance with
Section 2.11.2, step 3.
2.5.5
Com 3 Duplex (SAT PHONE) Function for COM 3
As installed in the standard configuration, the PMA7000BT Com 3 function operates conventionally. Push-
ing the Com 3 Xmt button places the transmit and receive audio from Com 3 in the headset and applies the
pilot or copilot microphone to the Com 3 when the appropriate PTT is activated.
If J2, Pin J is connected to aircraft ground, the PMA7000BT is forced into Com 3-Duplex mode.
The pilot can select phone booth mode by just pressing Com 3 transmit button on the audio panel. The co-
pilot and passenger audio require hook switches to connect the COM 3 output; the PTT for Com 3 is inac-
tive. Audio from Com 3 is presented to the headset. This allows a telephone-like audio interface. The COM
3 input and output are compatible with aviation radios.
The COM 3 input and output are compatible with general aviation radios. Push-To-Talk might be desired
during satellite telephone communications; this can be accomplished by J2, Pin J open on the connector.
However, if J2, Pin J is connected to aircraft ground (either directly or through a switch), the PMA7000BT
is forced into Com 3-Duplex mode. In this mode, the COM 3 input and output is compatible with many
satellite telephones utilizing the hands-free headset interface
Unauthorized use of unapproved cellular telephone devices in aircraft is subject to FCC enforcement
action, which may include a $10,000 fine per incident. PS Engineering, Inc. does not endorse using
unapproved cellular telephone equipment in flight, and takes no responsibility for the user’s actio
n.
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 manufacturer's installation manual.
2.5.7
"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 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.