Com Radio Setup - Garmin GNS 480 Installation Manaul

3.2.1.5 COM Radio
The COM Radio Setup function is used to modify the RF Squelch and Mic Gain levels. Typical values
from the factory are RF Squelch = 56 and Mic Gain = 255, which are satisfactory for most installations.
The RF Squelch value is used by the COM function to control its squelch level. The larger the value that is
set the stronger the signal must be in order for the radio to break squelch. To edit the RF Squelch value,
press the EDIT RF SQUELCH line select key. Turn the small, inner knob to adjust the squelch value (the
RF Squelch value is restricted to a number from 25 to 100). When the desired value is selected, press the
MENU/ENTER key or the SAVE RF SQUELCH line select key to save the setting.
The microphone gain is used by the COM function to control the microphone pre-amplifier gain. The
larger the value that is set the higher the pre-amplifier gain is. To edit the Mic Gain value press the EDIT
MIC GAIN line select key. Turn the small, inner knob to adjust the gain value (the Mic Gain value is
restricted to a number from 0 to 255). When the desired value is selected, press the MENU/ENTER key or
the SAVE MIC GAIN line select key to save the setting.
3.2.1.6 Miscellaneous Setup Items
The Misc Setup function is used to configure the unit to ignore the CDI select bezel key and CDI select
discrete input (refer to 2.8.9.1). While on the Ground Maintenance SETUP menu Page 2, press the MISC
line select key.
Press the CDI SEL line select key to toggle between USE (for installations that will utilize the GNS 480
CDI bezel key to switch between NAV and GPS) or IGNORE (for installations where it is desired that the
CDI bezel key be inoperative). If the CDI Select is set to IGNORE, the field beside the CDI key will
always be GPS, regardless of CDI key presses. When set to IGNORE, the main analog CDI output (refer
to 2.8.2) will always output VOR/ILS information, even though GPS information will be displayed in the
CDI window and 'GPS' will be annunciated beside the CDI key.
Press the ALT SEL line select key to toggle between USE (Altitude can be used) and IGNORE (for
installation where the FADC is not certified for use with Transponders). If the Alt Select is set to
IGNORE, all altitude data from the FADC will be ignored. Altitude from a Altitude encoder if available
will be use in its place.
Press the ENG SEL line select key to toggle between SINGLE (Aircraft has one engine fuel flow sensor)
and TWIN (Aircraft has two engine fuel flow sensors). If ENGINE CFG is TWIN the NAV Map fields
can be configured for Fuel Flow L & Fuel Flow R. ). If ENGINE CFG is SINGLE only Fuel Flow will
be selected. If SINGLE is selected when two Fuel Flow sensors are present and no fuel remaining is
GNS 480 (CNX80) Installation Manual
Figure 3-8. COM Radio Setup
560-0982-01 Rev L
Post-Installation Configuration & Checkout
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