Mission Accomplished!

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!

3 Comments on “Mission Accomplished!

    • Thanks again Ed – I’m going to try the other ideas that you have floated as well. Isn’t funny how a “simple vertical” can be so complex?

      Now I understand why there aren’t many 160 / 80M antennas out there!

      Like

      • Sadly the Johnson Matchbox link-coupled tuner didn’t cover 160 as built. But there have been various mods, like switching in sets of doorknob caps in parallel. I’ve not done other than breadboard with it, but see no reason it wouldn’t work.

        Best to you, OM.
        AG6CX

        Liked by 1 person

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