--------------------------------------------------
From: "Carl" <km1h@jeremy.mv.com>
Sent: Sunday, December 04, 2011 6:04 PM
To: "Jim Thomson" <jim.thom@telus.net>; <amps@contesting.com>
Subject: Re: [Amps] 2 x 3-500Z filament choke + 30/60/80A fil chokes
> The 33 Mix is what gets you down to 160 without having to get fancy with
> using the choke as part of the input network. The network programs dont
> calculate for the hammy hambone "engineering".
>
> Carl
> KM1H
>
### say what? 33 mix is low freq stuff...and will also work just fine. It
has a mu of
600. Type 43 has a mu of 800. I had zero access to type 33 material in
rod form.
What you don't want is type 61, with it's mu=125. It won't provide
enough uh
on the low bands at all. If type 61 is used, the type 61 rod can be
removed, and type
33/43 slid into place.
## The only place where you will ever see the fil choke being part of the
tuned input
is on Rich measures 160m SB-220 conversion article. The stock heath fil
choke is just
9 uh per winding. Instead of installing a bigger one, he instead adds an
additional 900 pf in parallel
to the C2 cap [closest to the cathode] of his new 160m tuned input PI
net.
That extra 900pf cap will parallel resonate with the 9uh fil choke on 160m
only. That makes the
sb-220 fil choke look like a High Z on 160m. That was a one off unique
method to get around
installing a bigger fil choke for the 160m mod. What's slick about his mod
is... the extra 900 pf
is only added in..via the 160m tuned input. It's out of the circuit on all
other bands.
## The story I got was the fil chokes XL should be 4 x the cathode Z.
With a 50 ohm input Z,
that equates to 200 ohms of XL on the lowest freq... which equates to 9 uh
on 80m....and 18 uh
on 160m.
## what's hammy hambone engineering, your typ arrl fubar handbook ?
## hey carl, what was that giant rod you used to sell way back in the
80's ? It was
12" long x 1" diam. I kicked myself for not stockpiling a few of em.
Thought it was
type 33 ? I see you can get 6-8-10 ga magnet wire easily like from
planet wire etc.
Apparently you can get 4 ga magnet wire in chile.
later... Jim VE7RF
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