[Amps] Rf choke

[R.Measures]

On Nov 21, 2005, at 2:07 PM, Kenneth D. Grimm, K4XL wrote:

> R.Measures wrote:
>
>> On Nov 21, 2005, at 12:08 PM, wc6w at juno.com wrote:
>>
>>
>>> Hi Jan,
>>>  The theory behind those "sectioned" chokes is that all the 
>>> resonances will fall somewhere friendly.  In the real world they 
>>> tend to behave rather similar to contiguously wound solenoids.
>>>
>>
>> In my experiences, this was also the case, Marv.  The notion that two 
>> choke sections can be decoupled by placing them end-to-end instead of 
>> at right angles is quite laughable.
>>
>> cheers
>>
>>
>>>  For some background info on plate parallel feed RF chokes and 
>>> alternative solutions see:
>>>
>>> http://wc6w.50webs.com/wc6wamps/index.html?fr62.html
>>>
>>> 73 & Good afternoon,
>>>  Marv WC6W
>>>
>>>
>>> -- jan <jan at on6zg.be> wrote:
>>> Hi,
>>>
>>> I´m building a HF gs35b amplifier, but i´m having a problem with the 
>>> rf
>>> choke in the High voltage line.
>>> On 15meters the choke gets hot.
>>> Has anyone got specifications for building a 160m to 10m rf choke? 
>>> I´ve
>>> found several amps with a choke like this inside:
>>> http://www.kvindesland.no/yl2qm/images/rfc.gif
>>>
>>> thanx for any help
>>> ON6ZG, Jan
>>>
> OK, now on behalf of us non-cognoscenti, are you guys saying that the
> segmentation of a solonoidal plate choke cannot be wound so as to
> avoid resonances at undesired frequencies?

Yes

> I don't want to waste my time trying to wind a new choke for my amp 
> that
> does unhappy things every time I try to use it on 24 MHz if it is a 
> known fact that
> segmentation doesn't work.
> Anyone want to guarantee this?  :-)

Ken -- I built two quite similar single-layer solenoid-wound HV RFCs 
suitable for one 4a tube such as the 8171.  One RFC had gaps like the 
one shown in the Handbook, the other one had no gaps.  The HF 
resonances were shockingly similar.  The lesson here is believe not 
everything in print.   Decoupling RFCs is best done by placing them at 
right angles.

- " I do not feel obligated to believe that the same God who has 
endowed us with sense, reason, and intellect has intended us to forego 
their use."
-  Galileo Galilei
end
>
> 73,
>
> -- 
>
> Ken K4XL
> k4xl at arrl.net
>
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>
>

Richard L. Measures, AG6K, 805.386.3734.  www.somis.org