H. The VHF transceiver also contains a monitoring stage for the supply voltage
which is activated when the VHF transceiver is switched on. If the supply
voltage drops below 10.5 V, the segments of the LCD begin to flash.
I. In the mode 3, the supply voltage and temperature is displayed in the bottom
line of the LCD.
J. Aircraft internal communication is possible in the IC (intercom) mode. Activation
is by means of an external IC button (or switch) which is to be connected to the
equipment connector.
K. The AF auxiliary input enables AF signal switching of auxiliary units in the air-
craft. The switched AF signals can, however, only be monitored in the reception
mode.
L. If illumination of the LCD is required, this can be connected either directly to the
supply voltage or via a dimmer.
M. The scan function can be switched on in the service mode and called up in
mode 2. The active frequency is shown in the top line of the display and the
bottom line shows the associated storage channel with the preset CS. In the
scanning mode the stored frequencies in the storage channels are scanned in
succession at 200 ms intervals. When an evaluatable reception signal is found,
the VHF transceiver remains on this frequency until an evaluatable reception
frequency is no longer present. It then begins to scan all the stored frequencies
again in 200 ms intervals. In the service mode, the hold time between the end
of an evaluatable signal and the continuation of the scanning of the next chan-
nels can be set to between 0 and 60 seconds.
N. Special functions
VHF transceiver contains some special functions which can be set in the
service mode.
l Adjustment of volume IC, sidetone, AF auxiliary and the sensitivity of dy-
namic microphone.
l The switch-on threshold of the squelch can be set in the service mode.
l The frequency setting can be inhibited. The VHF transceiver then opera-
tes only on the frequencies stored in the storage channels.
l The storage of frequencies in the storage channels can be inhibited.
l Stored frequencies can be erased.
l Access to the service mode can be interlocked with a 4-digit password.
l The scan function can be switched on.
INSTALLATION AND OPERATION
AR 4201 - ( )
Page 1-2
23-10-01 December 15/95
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