Version 16.10 AF-6600 AF-5000 Series Install Manual 61
Shielded audio cable is required In an audio system such as the AF-INTERCOM-2S, it is required to
use separate shielded cables for microphone and other input signals, and headphone and other output
signals. If separate shielded cables are not used, squealing, hum, and other undesirable audio will likely
be heard. To reduce electrical noise from being induced into audio circuits, separate the audio wiring
as much as possible from other electrical wiring.
Audio cable shields must terminate at a common point A ground loop is more than one
electrical path to ground. Ground loops are a common source of noise with audio systems. Because
other electrical loads can cause large current flows in a ground path, audio system grounds should be
isolated as much as possible from electrical ground. Except where specifically directed in the diagrams
above, the shields for all audio cables should terminate at a single point, with that point connected
directly to Pin 1 (Master Ground) of the AF-INTERCOM-2S. Additionally, the point should be as close to
the AF-INTERCOM-2S side of your harness as possible.
Dual Radio PTT Installation
The AF-INTERCOM-2S has two separate radio outputs that can each be connected to an individual
COM radio. The PTT output, therefore, needs to be externally switched so that you can control which
radio receives the PTT signal (and therefore transmits). An external single pole, double throw (SPTD)
switch (not provide) should be installed to select which radio the PTT is connected to. See the wiring
schematics above (AF-INTERCOM-2S pin 12) for a depiction of this connection.
Headset jacks must be electrically isolated from the panel If your panel is
electrically conductive (such as aluminum), the headset jacks must be electrically
isolated from the panel. Insulating washers are included with the headset jacks.
Another method is to mount the jacks on a small plastic plate instead of mounting
the jacks directly to the panel.
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