ATR833S / P/N 833S-(Cxxx)-(Cxxx)
Operation and Installation
44
Document-Nr.: 01.142.010.71e / Revision:1.03
4.9 Microphone / Intercom settings
The settings of MIC and VOX values are essential for Intercom. The
respective configuration options are described in section 2.5.3
(VOX=threshold level) and section 3.6 (MIC input sensitivity)
If the VOX automatic is deactivated with VOX=0 then the intercom is
activated using the intercom switch (not PTT), which connects PIN 7
(intercom) of the equipment connector to GND.
For operation with VOX activated PIN 7 has to be connected to GND
permanently. Transmission only operates when PTT is pressed.
The suppression of background noise is only possible when using
differential microphones, as they are usual with modern headsets.
Normal electret microphones are not suitable.
4.10
Post-Installation Check
When installation is completed all steering and control functions of the
aircraft are to be examined, in order to exclude disturbances by the
wiring. The SWR shall not exceed 3:1.
Furthermore a test flight is recommended in order to guarantee the
proper in-flight operation of the radio; note the following:
In a flight altitude of at least 2000 ft contact a ground station in a
distance of at least 50 km (30 nautical miles).
Pay attention to unusual electrical interference.
If possible, perform the radio test on frequencies within the upper
and lower VHF communication frequency range
The HF antenna wire must not be included in any other
cable sets, for example power supply or microphone. It must
also not be placed together with other antenna wires, for
example NAV or Transponder.
A certified maintenance shop must verify proper operation of
the VHF Transceiver System.
