--------------------------------------------------
From: "Missouri Guy" <n0tt1@juno.com>
Sent: Saturday, January 16, 2010 8:22 PM
To: <Jim.thom@telus.net>; <Amps@contesting.com>
Subject: Re: [Amps] KK5DR's ferrite loaded plate chokes.
>
> On Sat, 16 Jan 2010 18:59:18 -0800 "Jim Thomson" <Jim.thom@telus.net>
> writes:
>> I Checked a bunch of really old e-mail, and notes. The folk's who
>> duplicated the KK5DR plate choke, using 1/2" type 43 rod, stuffed
>> into the inside of a hollowed out 1" OD Teflon rod
>> had nothing but grief. All the rods overheated ! In some cases,
>> the rod actually launched itself out the top !
>>
>> Either 1" type 43 rod is required, [like several type 43, 1"
>> Od beads slid over the 1/2" rod].... or several type 43 rods
>> bundled together.
>>
>> Perhaps type 43 material is the wrong stuff to be using for a
>> plate choke...esp considering the typ plate load Z's involved ??
>
> Yes, wrong stuff to use. As an experiment, I made a much smaller choke
> using #43, then measured the reactance with a small current flowing
> through the windings. The reactance dropped dramatically!
> Then I used a powdered iron core and that made a huge
> difference, with almost no reactance decrease at all.
## well, that IS a stunning revelation.
## I was sure powdered iron might be the ticket.
Powdered iron has less mu, so it wouldn't provide as much uh.
Perhaps #2 mix would work. [ red cores] I don't think u can get #2 mix
in rods though ?
#2 is used in tank coils.. like T-225-2B, etc. Still, it might provide
enough MU, to do the job,
but I doubt it. The stock coil couldn't be much more than 45-50 uh [ so
1st series resonance >35 mhz]
The #2 powdered iron [ or another type of powdered iron mix] would have to
have enough MU, to increase the
uh up to at least 150uh. Perhaps if you had enough of it stuffed in
there, you could get the 150-180 uh.
## For a good laugh, check out KK5DR's ultimate.... 'choke resonance
test setup',
complete with scope, sig gens etc, it's on his site. That set up is
totally flawed, and got trashed on
the other amp reflector months ago.
Later... Jim VE7RF
>
> 73,
> Charlie, N0TT
>
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