Garmin GTX 327 power

[Tbone]

I?m working on a transponder install (GTX 327). I have connected the power wire to CB, the Avionics wire to a switched power. When I power up the aircraft the transponder is off. Good. When I power the Avionics master up the transponder powers up. Good. Now when I turn off the Avionics master switch off the transponder stays on. Not what I expected. Can someone tell me what is the purpose of the master avi wire going into the transponder is for? My thoughts were that the Avionics master would (should) turn the transponder on AND off. No? It it just a ?sense?wire?

[bobnoffs]

i think that it tells the transponder to power up every time the master is turned on vs. waiting for the on button on the transponder to be pushed.

[Tbone]

Yes it turns it on but when I turn avi master switch off is still stays on! Is that how it’s designed?

[g3xpert]

This is as designed behavior. The following note is from the installation manual:

"Avionics Master On, when tied to 11-33 VDC input provides automatic unit power up. When power is applied the unit will power up in the last mode selected."

If you want the unit to power down when you turn off the avionics bus, you could move the circuit breaker from the main bus to the avionics bus.

Thanks,
Levi

[Tbone]

Thank you Levi ! I thought I was going crazy. So the avi master wire is just a trigger wire to turn it on but not off? Understood.

[Geico266]

How do we set the GTX327 to turn on automatically with the avionics master?

[g3xpert]

Originally Posted by Geico266

How do we set the GTX327 to turn on automatically with the avionics master?

Hello Larry,

Just connect the avionics master power to both pins 1 (avionics master on) and 15 (input power).

Whenever the avionics master switch is turned on, power will be applied to both pins and the GTX 327 will power up automatically without pressing any buttons.

Thanks,
Steve