320A Transponder pinout...couple of unknowns

cjensen · #1 02-17-2009, 09:40 AM

I am working on building the transponder harness, and I have all the wires matched up to the encoder for the Gillman code, and the grounds figured out. I have a couple of questions on a couple other pinouts though...

Pin 8 is the "External Ident"...???

Pin 14 is the "Switched Power Output"...???

Pin 15 is "Aircraft Power"...obviously need this, should go to the bus...

Pin 16 is "External Standby"...???

Pin 17 is "External Suppression (Suppress I/O-GTX320A)

Can someone shed some light on these five pins? Really just 4 since aircraft power is going to be used...but what about the others?

noelf · #2 02-17-2009, 10:12 AM

between the Pilots Guide and the Installation Manual.

External Ident...can be wired to a momentary (stick) push button and used in the same manner as pushing the IDENT button on the Txponder.

Switched Power Out...can be used to power an external blind encoder. This can save an external fuse (or CB) and only provides voltage when the txponder is powered on.

External STBY...sorry, I do not specifically remember this one, but I believe it can be wired in to the landing gear squat switch to automatically switch the txponder into / out of? standby operation dependent on the AC being on the ground or in the air. It seems I recall the 430 units have an output that can also be used to drive this function from a derived GPS airspeed value.

External Suppress...is used in dual txponder installations. This will inhibit the txponder from responding to interrogations...and allows the "other" txponder to respond. This can be wired to an external switch that selects one and de-selects the other txponder.

cjensen · #3 02-17-2009, 10:25 AM

Thanks Noel...looks like I don't need to worry about any of those then...

I've read the install manual, but don't have a pilot's guide for it...bought second hand.

Thanks!

hydroguy2 · #4 02-17-2009, 10:32 AM

Quote:

Originally Posted by cjensen

.... but don't have a pilot's guide for it...bought second hand.....

chad, I am actually going to be in the shop today...shocker huh! anyway, I think I have a pilot guide for the 320. I'll check and if so I could make you a copy, if needed.

647jc · #5 02-17-2009, 10:37 AM

A nice PDF format installation manual is available at http://www.fokkervliegen.nl/GTX320A_InstallManual.pdf. I'm sure you can find other online sources also.

cjensen · #6 02-17-2009, 10:38 AM

Thanks fella's...I have the install manual printed out, and I think I can get by the rest of the way with that, and the info learned here today.

647jc · #7 02-17-2009, 10:56 AM

Pilot's guide available at http://www8.garmin.com/manuals/GTX32...ilotsGuide.pdf . Not much of a guide but may be useful.