GTX 330 Transponder won't do auto airborne determination

Hey folks,

I just put a new GTX 330 Mode S tranponder in my RV-8 today. It seems to work great, displaying the TIS data beautifully, but it doesn't seem to do any "automatic airborne determination." No problem, I just turn it on after takeoff, but wondering why it won't seem to turn on automatically.

I have the GPS hooked up and inputting groundspeed, and it senses altitude as well. It is my understanding the thing is supposed to come on when it senses an altitude increase, or a groundspeed greater than 35 knots.

Anybody out there got any experience with this?

Thanks,

Rich

airplane photos at www.wilson235.com

Did you check the configuration? Squat switch should be set to NO, and Auto Standby to ON

Also check the firmware version (shown upon powering up).. At least on the 327, earlier versions required an update to get this to work.

Also check in config that you have the Serial inputs enabled...

Will check....

Thanks, that gives me a couple of things to check. Maybe my firmware is out of date, but I don't remember a page for "Auto standby ON". I do have a page with squat switch - off but not much else. Let me work with that tomorrow and maybe there's some options I didn't find.

All the RS-232 inputs are on and functioning correctly. Altitude and GS are detected properly..... so I'm guessing it will be something to do with the squat switch thing.

Thanks much,

Rich

PS - you a 777 guy?

Check your GPS settings. My GNS480 manages the transponder.

My GTX327 determines 'automatic airborne' without being connected to a GPS. So I am guessing the issue is with the settings eigher in the transponder or your encoder (I am assuming some sort of EFIS is being used as the encoder). Good luck.

Strange as it may seem

Guys,

Thanks for the inputs. Just screwing around with the transponder, I got it to auto detect buy you won't believe how.

Pushing STBY puts the transponder in standby. That seems pretty obvious. Just on a whim I tried pushing and holding the STBY button. After 5 seconds, it arms itself into an auto detect mode. And sure enough, I went flying and it worked like a charm.

This is not documented in the Garmin install manuals or the pilot operating manual anywhere, but it works. Strangest thing I've ever encountered in a Garmin unit. But at least it works.

Nowhere in the setup pages is there a configuration for auto standby or auto detect. Very odd. I'll send an email to Garmin and ask if this is how I'm supposed to be doing it and will post the answer here.


Thanks again everybody for your replies. They were ver helpful.

Rich
N707RW "Katie Sue"