I was talking with an avionics guy yesterday and we were talking about using my existing transponder and something like the uavionix skybeacon. He said that the older tube transponders had a variance of +/- 5% and if you pulled one out of your plane and looked at it on the scope it was probably worse. Apparently the new spec is +/- 1% and this could cause problems. I'm sure that he would like to sell me new equipment and installation services to put it in my Cherokee (my 14 won't be done by 2020), but is this a problem people are running into?