[Amps] Ferrite Core for 160M PI Output ?

[Carl]

----- Original Message ----- 
From: "Jim Thomson" <jim.thom at telus.net>
To: <amps at contesting.com>
Sent: Sunday, June 11, 2017 12:20 AM
Subject: [Amps] Ferrite Core for 160M PI Output ?


> Date: Sat, 10 Jun 2017 14:09:05 -0700
> From: Paul Baldock <paul at paulbaldock.com>
> To: "Amps group" <amps at contesting.com>
> Subject: [Amps] Ferrite Core for 160M PI  Output ?
> Message-ID: <593c5ff4.4bd1620a.e42b5.0bd9 at mx.google.com>
> Content-Type: text/plain; charset="us-ascii"; format=flowed
>
> <When I said Ferrite I should really have said Toroidal so as to
> include Iron Powder.
>
> - Paul
>
>
>
>
> What's the best PI Output Ferrite Core(s) to use for a 1.5KW tube amp?
>
> Thanks
>
> - Paul
> KW7Y
>
> ##  Powdered Iron.   #2  MIX.   These are the RED ones.
> T225-2B.   Beware, the T225-2A  is only .5 inch thick ...
> IE  laying on the table with hole pointed at the  ceiling,  its
> .5 inch tall.
>
> ##  The T225-2B  is  a full 1 inch thick.    You require at least 2 of 
> them
> for  1.5 kw out for cw  and  ssb.    For RTTY, you require 3 of them.
>
> ##  these have been in use since the 70s..for  160 + 80m.
>
> ##  I think marv calculated the heat at aprx 57 watts of diss, regardless
> of how many core are used.   They run hot..normal.
>
> ##  If 3 used, the entire mess ends up being  2.25 inch OD  x 3 inches 
> long.
> Bigger OD and length, once the wire is wound onto them.
> I found some air dux..which used 12  or 14 gauge wire.... and had the 
> turns
> spaced closer than normal air dux.   Worked perfect for the 160M 
> conversion
> project I was working on.   Zero heat vs the stack of torroids.  The air 
> dux
> weighed nothing vs the hefty weight of the 3 stack I also tried.   The 
> airdux
> ended up being aprx the same diam and length as the torroid stack.
>
> ##  space wide, the torroid stack save me nothing.  160m is pretty 
> forgiving,
> with long leads, coil close to cabinet side walls etc.
>
> Jim   VE7RF



** The T225-2B is sometimes hard to source so a pair of the A version is 
equivalent. A pair of the more common T200-2A or 2B is what was used in most 
amps.
Ive run two 200-2A's on 160 for about 30 years in a modified NCL-2000 
without problems at 1200W including AM.
Dont forget to wrap each one with a layer of Scotch 27 HV tape and then wrap 
the stack before winding. I also used #14 stranded Teflon wire as that was 
what I found on a big reel at a scrap dealer.

Carl 


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