Ed, AG6CX reminded me of a QST article written by Phil Salas regarding a 41′ vertical that can be used on all bands 160 – 10M. Its funny, but I actually had purchased the same MFJ airdux style coil several years ago, and its sat unused in my big junk box. Well, actually, I have occasionally used it to play around with matching circuits. Luckily, the 1:4 UNUN that will be here in a few days, and the relays and the coil are already all on hand. I will think a bit about this – what Phil has done is added 160 and 80M to his 41′ vertical – that already was fine on 40 – 10M. My solution is just a different shade of grey – but both attempt to solve a very similar problem.
The Inverted L gives me top loading which I am sure is better than trying to use a 41′ vertical on 160 and 80M. But with the top loading in place – the matching at the base is fine – I don’t think just having base loading is really that efficient – at least according to the ON4UN Low Band DXing book. I went through this exercise with the Cushcraft MA-160V a few years back.
Compare and contrast Phil’s circuit with mine:
Pound for pound they are similar, but because I have an Inverted L, the biggest challenge is matching 80M. Since my tuner and amp are already happy on 160M with just the 1:1 curent choke, and because I am not stressing the 1:1 current choke – as you would trying to use an in shack tuner with a 41′ vertical with that same current choke – the Inverted L is significantly different in this regard. Its really great to look at both solutions and then consider what each is trying to solve.