----- Original Message -----
From: "Jim Thomson" <jim.thom@telus.net>
To: "Carl" <km1h@jeremy.mv.com>; <amps@contesting.com>
Sent: Monday, December 05, 2011 4:19 AM
Subject: Re: [Amps] 2 x 3-500Z filament choke + 30/60/80A fil chokes
>
>
> --------------------------------------------------
> 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.
** I dont know where you are getting 43 mix rods Jim since Fair-Rite doesnt
make them.
The 33 mix is the choice plus it is temperature stable to a high degree.
>
> ## 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.
** Rich must have copied that from Dentron which used a 4" 33 mix down to
160.
>
> ## 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 ?
** Also a lot of the garbage called engineering on many web pages.
>
> ## 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 ?
** R33 -75-1200. I saved a few for myself but finally put them on Fleabay
back when I told you I was going thru old stock here. I dont build 3X3's any
longer.
I see you can get 6-8-10 ga magnet wire easily like from
> planet wire etc.
** I still have a lot of 10, 12 and 14.
> Apparently you can get 4 ga magnet wire in chile.
>
> later... Jim VE7RF
Carl
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