On Thursday, April 2, 2015 at 5:42:12 PM UTC-7, Bill T wrote:
John, I'm sure Darryl will be along shortly.
Gliders are not required to have a transponder or ADS-B Out.
You are not required to add Out GPS data to the Trig unless you chose to. But if you do it must meet the standards.
FAA has recently reworded the language that allows "Experimental" kit built aircraft to install non TSO'd ADSB out systems as long as they meet the same standards. I'm not sure if that applies to experimental gliders.

We have Trig21 on some of our gliders, inside the Mode C Veil, we are not planning to add GPS to the Trig.
BillT

Bill is right. You won't need to do this, not unless the regulations are changed, and that would be a huge surprise.

You need to read 14 CFR 91.225.

Because of the the glider/electrical system exemption you can fly within a Mode C Veil after 2020 without ADS-B Out. Obviously when that close to lots of traffic I'd hope glider owners do equip their aircraft with a transponder, as you have--thanks! And that transponder provides lots of protection, importantly it makes you visible to the TCAS systems in just about all airliners and fast jets.

If you chose to install ADS-B Out and your glider is certified then you must meet all the requirements of the 2020 ADS-B Out Mandate, that unfortunately is not something that a Trig TT-21 transponder can do, you need to have a TT-22 because of FAA's silly power requirements for ADS-B Out. And yes you would also likely need a TSO-C145a (or later) GPS source. If your glider is experimental then you have cheaper options (but you need to be careful that say if you connect a commodity GPS to the Trig it won't give you any post 2020 mandate privilege e.g. not allow your glider to enter class B or C airspace... probably not an issue :-)).