I agree with Phil on this choke ... as he stated. It has worked very well
for me on a couple projects.
Terry W6RU
----- Original Message -----
From: Phil Clements <philk5pc@tyler.net>
To: <W8JI@contesting.com>; <Amps@contesting.com>
Sent: Sunday, March 12, 2000 9:15 AM
Subject: Re: [AMPS] Chokes
>
> > Stray capacitance at the middle of the choke is the problem at the
> > first resonant frequency, so removing turns there and making an air
> > gap will shift the first series resonant frequency higher.
>
> The choke sold by RF Parts Co. and Ameritron has been a "God-send"
> to me in the last few amps I have built. I tried several other things
over
> the years; using two chokes and switching one in and out, (good, but
> expensive) mounting two chokes at right angles, (crispy-critter time)
> and using B&W 800's and 802's, even though the L was too low for
> adequate operation on 160 meters.
>
> Let's look at the RF parts/Ameritron choke. It is around 210 uh on a
> 1" x 5 1/2" ceramic form. The windings are split into three sections;
> 5/8" 7/8" and 1 1/2". The distance between windings is 5/8" and
> 1 1/4." The 1 1/4" gap in the winding is in the center of the form.
> The first resonance is marked on each choke, which is parked
> between 11.7 and 12 mhz.
>
> I think the reason that the "gapped choke" described in the ARRL
> handbook does not change much from a standard winding is that
> the gaps were too close to their adjacent windingsto make much
> difference, as Rich has pointed out and I have confirmed by building
> one. I saw no advantage to the ARRL choke at all.
>
> Here are some proven facts about the RF Parts/Ameritron choke.
> 1. It works in a wider variety of layouts than other chokes.
> 2. It works from 160-10 meters and runs cold on all bands @ 4 KW.
>
> The argument can now start on the hows and whys, but I use this
> choke exclusively now on all my projects. It saves a lot of time,
> money, and chassis space. It does the job on 9 ham bands and
> runs cold while doing it. Just what I needed!
>
> (((73)))
> Phil, K5PC
>
>
>
>
>
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>
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