>Hmmm.... "hot spots" .... Sounds like grade 9 physics :)
>
They exist at series resonances. I have seen choke fires. The trick is
to park 'em on WWV frequenciess or other out of the way spots at least 6%
away from ham (or CB) frequencies.
>Perhaps the correct utterance is that the windings gaps provide a
redistribution
>of the inter-thread capacitance that can and will form an resonant circuit
>:)
>
maxi-Chortle
>In other, simpler, words, the gaps prevent the accumulation of capacitance
>and/or inductance
>for a specific frequency. Common occurrence with LONG and NARROW coils :)
>
>The same effect can be achieved by having a coil that allows for some
>spacing (at least
>one diameter of the wire) between all threads, but this makes it to long
>for a practical application.
Agreed. The work-around is to mount the sections at right angles or
short thew big-un with a vacuum-relay on the higher bands.
>
cheers, Alex
>
>> -----Original Message-----
>> From: amps-admin@contesting.com [mailto:amps-admin@contesting.com]On
>> Behalf Of Tom Rauch
>> Sent: Sunday, June 30, 2002 8:51 PM
>> To: 'Amps'; Phil Clements
>> Subject: Re: [Amps] choke resonances
>>
>>
>> > Please inform us, Tom, if you his name, the person who
>> > wound up one of these things for the first time. I would like
>> > to ask him his reasoning for making gaps in the winding.
>> >
>>
>> Someday when I have time I will put some amplifier stuff up on my web
>> page, and testing chokes should be one of the more useful things.
>>
>> The gaps are there because those areas were "hot spots" where
>> voltages were highest when series resonances were checked. Removing
>> turns from the voltage hot spots has by far the largest effect on the
>> series resonance frequency compared to changes on other frequencies.
>>
>> With that in mind, if you want to move a series resonance don't just
>> peel turns off on the end, remove turns at the area of voltage peak.
>> Doing so will let you move the series resonance up much more rapidly,
>> because you are removing both inductance and capacitance from the
>> critical area.
>>
>> 73, Tom W8JI
>> W8JI@contesting.com
>>
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>>
>
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>
- R. L. Measures, a.k.a. Rich..., 805.386.3734,AG6K,
www.vcnet.com/measures.
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