Transponder installation article- Soaring Magazine

On Wednesday, December 23, 2020 at 8:49:56 PM UTC-5, John Johnson wrote:
On Wednesday, December 23, 2020 at 12:11:12 PM UTC-7, Dan Marotta wrote:
On 12/21/20 5:19 PM, John Johnson wrote:
Should I assume it is not legal in the US to use a TT21 with a TN72 for ADS-B out in an experimental glider? That combination is ok in Europe (I think) with the difference being the US wants 2x the xmit power for ADS-B (TT22 at 250W) vs the 125W output of the TT21. I would like to think that having otherwise compliant, lower power ADS-B out is better (and not illegal) than no ADS-B out in an aircraft that is legal without ADS-B.
Probably not a realistic hope - but it would save me the not trivial expense of upgrading my TT21 to a TT22.

JJ

I don't see why you couldn't use the TT21, but the price difference
between the TT22 and the TT21 is only $157. Why wouldn't you go for the
higher power and legality above 15,000'?

Rather than upgrade, why not sell the 21 and buy a 22?

--
Dan
5J
Dan, I suspect the cost to replace my TT21 with a TT22 is a lot more than $200 - probably closer to a $1000. Since I can legally use my TT21 for ADS-B out everywhere I fly (and I can always upgrade to a TT22 later for no additional cost penalty), I'm not sure what I gain. As near as I can tell, I'll essentially have the same ADS-B out visibility and be experimental glider legal everywhere I fly. I do appreciate the advice.
In the meantime, if anyone is looking for a used TT21, let me know and I'll consider your offer.
JJ
The 21 can be upgraded to a 22 by Mid Continent and then you can add the TN 72 as the ADS B out. Don't know today's price for the conversion, but when I did it a year ago, it was very reasonable.