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On Sun, 31 Dec 2017 13:40:21 -0600, W7RY wrote:
>
>Tapped tank circuits are a problem.
REPLY:
The solution is not to tap them. Wind a separate coil for each band
and orient them 90 degrees to each adjacent coil. Takes up only a
little more space than a tapped coil and avoids the problem of
unwanted coupling within the coil.
Join them together on a series of ceramic standoffs and run the joined
point to the bandswitch. Put the ten meter coil closest to the
bandswitch of course. Works like a charm.
In my homebrew 8877 amp I used #4 solid copper wire for each coil. Big
enough to never overheat and rigid enough to be self supporting
without any kind of braces except for 160 meters. The 160 meter coil
was so long I did add a third standoff in the center for support.
73, Bill W6WRT
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