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INSTALLATION SECRETS
Automatic GPS Gain Enhancement Selection Using the Garmin 430

Rodney Sinclair, Tech Rep

Since the S-TEC Systems Twenty, Thirty, 40 & 50 have advanced GPS gain enhancement circuits which require an external ground, why not have the Garmin automatically switch this feature on and avoid adding another switch?

The Garmin 430 can automatically enable this feature by providing a signal called GPS annunciate which transitions to logic low when GPS is selected. By placing a common rectifier diode between this output and the GPS Gain Enhancement Input, switching will occur at the required time without the use of extra contacts.