ORIGINAL MESSAGE:
On Thu, 09 Aug 2012 15:55:21 +0000, Manfred wrote:
>Instead of a simple plain parallel resonant circuit, which would need to
>be bandswitched, a simpler solution is to include a basic low pass
>filter section in PI configuration, that cuts above the highest band,
>and absorb the tube's capacitance in it. Such a basic low pass section,
>designed to cut off above the 10 meter band, will require about 100pF on
>each side. So it can be built with the 100pF on the input side but only
>20pF on the output, and the tube's capacitance will complete it. The
>result will be low SWR on all bands, without needing a band switch
>section at the input.
REPLY:
Thanks, Manfred. I will have to try that when I get some time. As I mentioned
in another post I had no success trying to broadband the input. Perhaps your
approach is the answer.
Unfortunately, the amp I built back then has been cannibalized for parts so it's
no longer available to experiment with.
Someday....
73, Bill W6WRT
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