I'm amazed you could destroy two TXs this way actually???

My plan to put a 1A fuse in the primary did the trick - with no load on the secondary it shouldn't blow but it did telling us there was an excessive load. You really shouldn't have put larger ones in at this point.

You should use fast blow types for these tests by the way.

There is still going to be an issue with a load on the secondary that has started all of this....................