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1 - COM
190-00356-00 Rev B
Radio Volume / Auto Squelch
Section 1
Communicating Using the
GNC 420W/AW and GNS 430W/AW
Some models of the 400W-series feature a digitally-
tuned VHF COM radio that provides a seamless transi-
tion from communication to navigation. The GNC
420W and GNS 430W’s COM radio operates in the
aviation voice band, from 118.000 to 136.975 MHz,
in 25 kHz steps (default). For European operations, a
COM radio configuration of 8.33 kHz steps is pro-
vided (Section 9 - Aux - Setup 2). The GNC 420AW
and GNS 430AW use a 16-watt transmitter, instead of
the standard 10-watt transmitter.
“TX” appears at the upper right corner of
the screen while transmitting.
Volume
COM radio volume is adjusted using the
COM
power/volume
knob. Turn the
COM power/volume
knob clockwise to increase volume, or counterclock-
wise to decrease volume.
Squelch
The COM radio features an automatic squelch to
reject many localized noise sources. You may override
the squelch function by pressing the
COM power/
volume
knob. This facilitates listening to a distant sta-
tion or setting the desired volume level.
Press the COM power/volume knob momen-
tarily to override the automatic squelch.
Note the “RX” receive indication when
receiving a station.
To override the automatic squelch, press the
COM
power/volume knob momentarily. Press the
COM
power/volume knob again to return to automatic
squelch operation.
420W / 430W Only
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