Hi Vic,
For some time now I've mulling over a very similar set-up here...only in my
instance, I was thinking of somehow shorting the bigger inductor whenever I
wanted to use the higher frequency bands, and letting the two chokes stay in
series for operation on 160-meters...
I was hoping to use a 200-uh. solenoid choke for the high frequencies, and a
multi-pi National choke (3.0 mh.?) for Topband.
I wasn't planning on using anything more fancy here for a switching medium than
a manually-inserted (by way of a wooden dowel) shorting banana plug. That, or a
mercury switch that might be somehow made to tilt "on command". I s'pose it'd
be a requirement, too, to somehow mount the coils at right angles to one
another...?
Interesting stuff, indeed...
I sure would be appreciative if you might keep us all informed as to your
progress in this regard, Vic, with my sincerest of thanks in advance...
~73~ de Eddy VE3CUI - VE3XZ
**********************************************************************************************************************
On 2011-06-09, at 8:43 PM, Vic K2VCO wrote:
> I'm planning another amplifier (2 x 4-400A, 1.8-28 mHz) and I was thinking
> that I would
> deal with the "RF choke problem" by having two chokes in series. The one
> nearest the
> plates will have enough inductance for 20-15-10 meters with no series
> resonances below 30
> mHz. The second will be 1 or 2 mh to provide enough inductance for the 1.8-7
> mHz bands. I
> will use a vacuum relay to connect a bypass capacitor from the junction of
> the two chokes
> to ground on the high bands. Of course there will be further bypassing at the
> cold end of
> the big choke.
>
> That way, both chokes will always be in the circuit to help keep RF out of
> the power
> supply but the resonances and distributed capacity of the large one won't
> upset the higher
> bands.
>
> Is this a good idea or am I missing something?
> --
> Vic, K2VCO
> Fresno CA
> http://www.qsl.net/k2vco/
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