Fuji, for the record, I asked a Dutch glider pilot who has the same type of glider as mine how he was able legally to fit a transponder, when under EASA there was at that time no approved scheme as far as I could find out.
I had hoped to be able to do what he did.
He sent me a drawing, and implied that they just did it without EASA approval. As far as I could find out, there was no EASA approval for installing one of any make at that time in this glider type. As I have posted before, there is now, but limited to three specific models of transponder which does not include Trig.
I don’t know which model transponder he fitted, but I don’t think Trig was available then. Without a major instrument panel change – and even then I don’t know how I would make more room – the Trig TT21 appears to be the only one I can fit, and it is not covered by an EASA approved modification for my glider. Other people with different instrument levels and specifications may have more room for other transponders. The Trig is the only one I am reasonably sure will fit in mine.
Chris N.