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Re: [Amps] Ferrite Core for 160M PI Output ?

To: "Jim Thomson" <>,<>
Subject: Re: [Amps] Ferrite Core for 160M PI Output ?
From: Paul Baldock <>
Date: Sat, 10 Jun 2017 22:45:11 -0700
List-post: <>
Thanks for the info Jim.

I'm working on converting and SB220 to a dual 6M, 160M amp. I've done lots of single band 6M conversions, so this will be interesting.

- Paul

 At 09:20 PM 6/10/2017, Jim Thomson wrote:
Date: Sat, 10 Jun 2017 14:09:05 -0700
From: Paul Baldock <>
To: "Amps group" <>
Subject: [Amps] Ferrite Core for 160M PI  Output ?
Message-ID: <>
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?


- Paul

##  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

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