Find some one with a Swan Mark 6 and look at it. See what they did
25 years ago.
Art
KB7WW
"a.p." wrote:
>
> Amp aficionados, et al;
>
> I have a 6 M SB-220 conversion that works quite well with
> one tube. Input SWR is 1.1:1 and output plate tune is at
> about 1/3 mesh. Efficiency is as expected. However, when I
> put two tubes in the beast I have to go to min plate C for
> max output. There's plenty of plate current and input SWR is
> just as good as for the one tube case. The output coil has
> been modified from 1.5T to 3T with out much change in the
> two tube performance. Any one got any ideas on "optimizing"
> the output pi for two tubes? Note I have done a few of these
> successfully but this particular amp is weird.
> Any ideas on what might be causing this?
>
> TIA
> Art
>
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