The Henry 8K uses 2 chokes and so do several commercial 2-30MHz amps. Some
switch, some dont.
Carl
KM1H
----- Original Message -----
From: "Eddy Swynar" <deswynar@xplornet.ca>
To: "Vic K2VCO" <vic@rakefet.com>
Cc: "Amps reflector" <amps@contesting.com>
Sent: Thursday, June 09, 2011 10:10 PM
Subject: Re: [Amps] RF choke switching
> 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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>> Amps@contesting.com
>> http://lists.contesting.com/mailman/listinfo/amps
>
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