Ident Button

Reply Light

 

 

 

 

 

 

 

 

 

Code Selection Knobs

Function Selection Knob

Function Selector Switch:

The function selector switch is a five position rotary switch. The five positions are:

OFF-Turns off all power to the GTX 320A (the unit should be turned off before starting aircraft engine(s).

SBY-Turns the transponder on, but when in SBY the unit will not reply to any interrogations.

ON-The transponder transmits the aircraft’s identification code (Mode A) but does not include altitude information.

ALT- The transponder transmits the aircraft’s identification code, in Mode A and pressure altitude (29.92 inches Hg) information in Mode C provided the aircraft is equipped with an optional altitude encoder. The unit is normally operated in the ALT position at all times unless otherwise directed by ATC.

TST-Moving the switch to the TST position tests the reply light. The function selector is spring loaded and must be held in TST position. When released, it automatically returns to the ALT position.

Any time the function switch is in the ON or ALT position the transponder becomes an active part of the Air Traffic Control Radar Beacon System (ATCRBS). The transponder also responds to interrogations from TCAS equipped aircraft.