[Amps] KK5DR's ferrite loaded plate chokes.

[Carl]

Insulation thickness comes into play here. A heavy double Formvar or other 
high heat/voltage coating can add to the apparent size.

Carl
KM1H


----- Original Message ----- 
From: "James Colville" <jimw7ry at gmail.com>
To: "Jim Thomson" <Jim.thom at telus.net>
Cc: <amps at contesting.com>
Sent: Saturday, January 16, 2010 10:36 PM
Subject: Re: [Amps] KK5DR's ferrite loaded plate chokes.


>I just wound an ameritron look alike with #28. It's larger than they use. I
> have an original ameritron choke to compare with. I think they must use 
> #29.
>
> My resistance was lower using #28 and it was less uH.
>
> 73
> Jim W7RY
>
>
>
> On Sat, Jan 16, 2010 at 6:59 PM, Jim Thomson <Jim.thom at telus.net> wrote:
>
>> 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 ??
>>
>> Type  43....  1"  OD bead's,  slid over  393 Teflon coax makes for
>> excellent Choke baluns.    The  1/2"  x 8"  long  type 43 rods  work 
>> great
>>  for   Bifilar's.  But in both those cases,
>> the Z is only  25-50 ohms.
>>
>> What would be an excellent solution,  would be a higher current version 
>> of
>> the  RF parts /Ameritron plate choke.  I have asked a few times  what ga
>>  wire is used in the Ameritron choke,
>> and can't get a straight answer.   I believe it's around 28 ga.       A
>> version made with 22 ga wire  would be  the ultimate solution.   I know 
>> how
>> Tom designed the Ameritron choke.
>> However, I'm not prepared to  sit there in the shop for months,  with a
>> vna, etc,  trying to  park  resonances.    The  2 x choke + relay version
>> was a  cheap way to get around the problem.
>> Incidentally, the choke relay coil  was activated by a 3rd wafer on the
>> tuned input switch.
>>
>> Later.... Jim   VE7RF
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