Date: Mon, 15 Oct 2018 10:44:23 -0000
From: "David Robbins" <k1ttt@verizon.net>
To: "'Amps group'" <amps@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
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