[AMPS] Chokes

[measures]

>
>
>>    An article by Bill Deane in "73 Magazine", September 1969, p. 147
>> describes a 90 uH choke with a (first) resonance at 43 Mhz.
>>
>>    The cogent details, to save everyone a trip to the library, are sixty
>> turns of #20 wire, space wound 4" long on a 3/4" diameter form with a 3"
>> x .33" ferrite rod mounted in the center of the form.
>>
>Hi Marv, and everybody,
>
>I ran this article by the reflector a couple of years ago. Very interesting.
>I saw a 3-30 mhz Harris amp some years back with an unbelievably
>short plate choke in it. (about 2 1/2 inches long) Turns out, this choke
>had a ferrite rod inside the form also. B&W uses this technology in their
>BBC model hi-power chokes.
>
>Mr. Measures quickly poo-poohed the usage of ferrite in an RF deck,
>but several commercial designs have been very successful with this.
>A caveat is that I have never seen a version of this choke work all the
>way from 1.8 to30 mhz. These appeared in articles and  amps
>before 160 meters and the WARC bands were of concern.
>There must be a reason that nobody I know of picked up the ball and
>ran with it after Mr. Deane's article was published.
>
Air core HV-RFCs never saturate.  Air cores never conduct.  Most of the 
articles I have read that use ferrites do the testing at around 5w.  .  
Presumably, a ferrite core HV-RFC works ok in 5w amplifiers.  

later, Phil,


-  Rich..., 805.386.3734, www.vcnet.com/measures.  
end


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