A yc-156 is hardly a compact tube. Why does size matter?
STAY AWAY from using toridal inductors for tank circuits. Unless its just
for the L coil in a PI-L.
Use good ole wire wound coil. #10 or 12 is more that large enough on 160
meters. I use #14 for the 160 meter coil added to my 8877 amplifier. More
that large enough, even for high duty cycle.
73
Jim W7RY
On Tue, Oct 16, 2018 at 11:31 AM Jim Thomson <jim.thom@telus.net> wrote:
> 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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