Figure 3-8 - Com Radio Setup - Garmin GNS 480 Installation Manual

Post-Installation Configuration & Checkout
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. The
Misc Setup page is shown in Figure 3-9.
It may be necessary to disable (IGNORE) the GNS 480 CDI select key for installations
with certain EFIS systems, where the navigation sensor selection must be accomplished
on the EFIS or its control panel.
3-8

Figure 3-8 - Com Radio Setup

NOTE
560-0982-01 Rev A GNS 480 (CNX80) Installation Manual