[Amps] stuff forsale!

[Jim Thomson]

Date: Mon, 15 Oct 2018 10:44:23 -0000
From: "David Robbins" <k1ttt at verizon.net>
To: "'Amps group'" <amps at contesting.com>
Subject: Re: [Amps] stuff forsale!

<They 'might' be ok on 160m, there are no big rtty contests on that band so
<haven't actually tested one there.  The problem with 40m and 80m is due to
<the shorted turns on the toroid creating lots of 
<heat which eventually melts
<down the plastic support.  I went through several of them before I modified
<one for 80m single band and this one forsale for 40-10m.  For the 80m single
<band one  I removed the network for the high bands and put a larger toroid
<on top of the rf deck.  For the 40-10m mod I replaced the 3 band toroid with
<one that has only turns for 40m on it and also opened up the tiny air holes
<a bit more.  As an added advantage they tune much nicer and run cooler than
<the originals since the toroid isn't wasting all that rf making itself hot!

<David Robbins K1TTT

## Why bother using a torroid at all ?   To actually do it right,  you end up with a lot of
bulk and weight.   3 X   T-225-2B  torroids in a stack, wound with  10 or 12 gauge wire ends
up being heavy. That was on a 160M  conversion.  Replaced that mess with a light weight piece 
of airdux...which ran stone cold.   You require at least  2 of the above torroids, each of which is
one inch thick, to handle 1.5 kw on SSB  +  CW.   And you need 3 of em, to handle  RTTY. 
This was using the red, type  2 powdered iron cores. 

##  I am in the process  of  helping to design a 160m  mono band  YC-156  for a friend. 
I have access to  .375 inch edge wound ribbon coil stock.... and also .5 inch, edge wound ribbon stock.
That will make for  the most compact  coil assy..... vs  using a tubing  coil.   Ceramic vac  tune cap used,
plus a 50-4000 pf  ceramic  vac load cap.   Vac relays on both input and output, full qsk, since the fellow is
a hard core  QSK  operator.   I also have some  8 gauge airdux coils, large diameter types, that would also work. 

##  although  160 M  RTTY might not be as popular as other bands,  newer mode like  FT-8, esp on bands like 160M,
would require a robust tank output  configuration.   This is not  rocket science.  The way to deal with heat...is to not generate
it in the  1st place. 

Jim   VE7RF