>Although I have not seen a great many amps in my day, the few I have always
>"pigtail" the coax runs...no connectorization inside the amp at all. It
>would seem to me (and I've measured it as well) that the shield "pigtail"
>is poison to achieving good input matches at 21 MHz and above. Obviously
>the introduced inductance would be that much worse at 3rd and 5th harmonic.
>My question: is it really the coax itself that causes such pain in the
>input, or is it the lack of proper coax termination? Would using quality
>bulkhead/panel fittings allow for remoting the input network the
>traditional 6-12" from the tube filaments?
I've not fiddled with moving my networks yet. However, I can tell you
one thing for sure. Inside my amp I have a piece of thin coax coming off
the bandswitch and going to a BNC panel mount. The "matching network"
end is where you would solder the coax. The connector end is in the tube
chamber. I had grounded the shield of the coax initially on one end on
the same ground as some of the matching caps. Yes, the ground leads were
a little long. While playing with the matching circuits and the MFJ-259,
I noticed that if I connected the OTHER end of the coax to ground (by the
connector) the SWR improved a good deal (I'd been planning on doing this
all along, BTW). So I would bet coax termination is a big issue.
You can bet I'll let everyone know once I start playing around with
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