The switched transformer Inverted L matching circuit works as designed. The biggest take away is that now I can run full power on 80M, which was the biggest challenge. This morning I woke up, came out to the shack and did one last test and found that the 160M position was not isolated when I was switched in position 1 and 2 – so I had to add another relay:
I know it has something to do with the fact that I changed the 160M position (which only goes through the 1:1 current choke) to be a switched on position instead of a default position. The additional relay ensures that all three positions are isolated – that there is no way to transmit back into another current choke or UNUN. I’m still scratching my head – but I probably need to create a switching “truth table” that has the NC, NO and voltage ON positions – then I might see what I experienced with the DVM. It seems redundant to have that new relay . . .
The biggest deal is 80M, and the fact that now the tuner sees what makes it happy range wise – so there is no folding back over 300 – 400 watts, and I can run full power. When I look at the Rig Experts AA-30 plots I don’t see why this is the case, but on the air, everything is great.
So while it has all worked out – there are two “mysteries” to solve with data. And this will be fun, but for now I can kick back and enjoy success with something I designed from scratch and built that helps me in a very practical way.
The UNUN’s “almost” obviated the need for the AT2K, but the SPE Expert 1.3K ATU is just “OK” – it really can’t match a 3:1 – its more like 2:1 which is the biggest disappointment with this amplifier – the Elecraft KAT-500 is WAY better. I would not recommend the SPE ATU at all.
But all in all I’m happy with this latest project – I’ve learned a lot and really like a switched circuit way better than one that uses a Stepper motor as the URAT project did. I’ll be pursuing high power switched circuits from now on.
I have two 160M 1/4 wl stubs at 75 ohms and will play with feeding this contraption with those stubs. I also have a massive coil that Ed, AG6CX gave me – and will see if maybe a switched hairpin is another option.
Thankfully, while DXCC runs out of gas after so many years, experimenting and trying new things seems to be an endless pursuit – hence why this hobby is as much a journey and expedition as VK0EK was!