Installation manual

AMX240 Audio Panel Installation Manual
200-890-0240 Rev. 02
Adding a high-performance audio control system, particularly in conjunction with high-performance active noise
canceling headsets, cannot improve on older avionics that were designed for cabin-speaker use. Avidyne makes no
claim that the audio panel will provide a noise-free audio quality under all installation conditions, particularly with
older avionics.
2.4.2 Power
The AMX240 is compatible with both 14 and 28 Volt DC systems. A five (5) Amp circuit breaker is required for all
installations. Power and ground wires should be #22 connected to J2 Pins 8 and 9. Connect airframe ground to J2
Pin 10 and 11 only.
2.4.3 Audio Panel interface
The AMX240 is designed to interface with standard aircraft avionics, and presents a 510  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 conductor of the twisted -
shielded cable.
2.4.4 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 radio installation manual for details.
2.4.5 Backlighting
Control of the unit backlighting and indicator intensity is through the aircraft avionics dimmer. For 14 V aircraft,
connect J2 Pins 6 and 7 to the aircraft dimmer bus, and pin 5 to ground. For 28-volt systems, connect pin 7 to the
aircraft dimmer, and pins 5 and 6 to ground.
When the aircraft dimmer is turned to minimum (or off) the lighting will automatically go to full bright.
2.4.6 Unswitched inputs
J1, pins 31, 29 and J2 pin 15 are unswitched, unmuted (by transmitter keying), inputs # 1, 3 and 4, respectively.
These inputs are presented to the pilot and copilot regardless of the audio configuration, and will always mute the
entertainment inputs. These 510Ω inputs can be used for altimeter DH audio, GPS waypoint audio, autopilot disco n-
nect 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 3 and 4 inputs are always presented to
the crew headphones and to the aircraft speaker.
Unswitched
Input
Hear in
Fail Safe
Hear in
Crew Headset
SPKR button
Select
Gain
1
Yes
Yes
No
1:1(fixed)
2
No
Yes
Yes
1:1(fixed)
3
No
Yes
No
Adjustable
4
No
Yes
No
1:1(fixed)
5 (jack)
No
Yes
No
1:1(fixed)
Table 2-2 Unswitched input table
Unswitched #2, J1 pin 44 is unswitched audio that is always connected to the Pilot’s headphone. However, this
unswitched audio is only presented to the aircraft speaker when the SPKR push button has been selected.
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.
Unswitched #1 is presented to the pilot headphone in fail-safe (off) mode.
NOTE