Garmin GTN 725 Cockpit Reference Manual page 19

Transponder Panel Page (Non-GDL 88 Installations with Mode C Transponder)
Standby Touch to place transponder in Standby mode. It is still
powered, but will not transmit information. STBY displays in
the squawk code field.
Ground Touch to place transponder in Ground mode. Refer to the
documentation provided with your GTX transponder for specific
information on this mode of operation.
On Touch to turn transponder On for Mode A operation. Will
transmit the squawk code when interrogated. ON displays in
the squawk code field.
Altitude
Touch for Mode C operation. The transponder will be on and
will transmit its squawk code and altitude when interrogated.
Reporting
ALT displays in the squawk code field.
VFR Touch to set the squawk code to 1200.
Enable ES Touch to toggle extended squitter.
Flight ID This field is inactive in non-GDL 88 installations.
190-01007-04 Rev. D
GTN 725/750 Cockpit Reference Guide (CRG)
Transponder
Mode - Green
indicates
current
condition
11