> 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.
(((73)))
Phil, K5PC
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