To auto-tune a frequency from a list displayed in the GPS window:
1. Press
C
twice to activate the cursor in the GPS window.
2. Rotate
O
to highlight the desired frequency.
3. Press
E
to make the selected frequency the standby frequency.
Another useful feature integrating the GNC 250’s navigation and communication
capabilities is the
Navigation Communications (NAVCOM)
page, which is
accessed using the
N
key. See pages 12-13 for more on the NAVCOM page.
The GNC 250’s
automatic squelch
and
volume controls
are located at the bot-
tom left of the unit, near the NavData card slot.
To adjust the radio volume:
1. Rotate the
B
knob.
Whenever the GNC 250 is powered up, the automatic squelch will be in the ‘on’
position, allowing only transmissions which are powerful enough for clear broadcast
to be received. Manual squelch control is not available.
To override the automatic squelch control:
1. Press the
Q
key. Press
Q
again to return to automatic squelch.
Whenever the GNC 250 is transmitting, a ‘tx’ icon will appear between the active
and standby frequency fields. If the microphone is stuck or accidentally left in the
keyed position, or if the headsets continue to transmit after the key is released, the
radio will timeout after 35 seconds of continuous broadcasting. You’ll also receive a
‘Stuck mic/Tx disabled’ message as long as the stuck condition exists.
31
REFERENCE
Airport
Information
‘TX’ indicating radio transmission.
SECTION
2
COMM FEATURES
Auto-Tuning/
Volume & Squelch
250 real 7/14/98 9:32 AM Page 31