My tiny indoor loop

As I have been asked about this, here are some details.

It has been used for 20m,17m and 15m. with powers up to just over 10W. It should work even better on 12m and 10m. This was a gift many years ago from the people who designed the Whizz Whip.  I have to admit that it works far better than I expected. As you know, it is tiny and just sits on the windowsill of the shack.

My main issue is getting a good match on the FT991A: if the SWR is too high the auto ATU just gives up, so my technique is to connect it first to the FT817ND on AM, tune initially for maximum noise, then tune the loop for lowest SWR then connect to the FT991A and engage auto-ATU. This seems to work just fine. Of course, with the FT817ND I just tune for lowest SWR. When tuned, the SWR is very low.

It looks like the match is made with a tapped toroid which is part of a tuned circuit. Being a loop, it is narrow band. With a thicker loop it could be even better, but even more sharply tuned.