Date: Thu, 26 Aug 2010 06:33:06 -0700 (PDT)
From: Jim Hoge <knowkode@verizon.net>
Subject: [Amps] triode or tetrode
I am kicking around the idea of a new amp ( I want 160m capability which my
current amp doesn't have) and have a few questions for the gurus and those that
have theses beasts. Am I better off with a triode or tetrode based amp? Does it
really matter? How about a one or a two holer amp? How much headroom should I
look for in a legal limit amp? Some designs are nearly at the limit of the
tube(s). How about auto tune capability? Do the amps that have this feature
find
the best match or will an override/manual tune do a better job? Any other
tidbits of wisdom?
Tnx,
Jim W5QM
Alpha 9500 Auto-Tune
HF Amateur Service
1.5 kW RF Amplifier $7,950 +
shipping and handling
Alpha 8410 Manual
HF Amateur Service
1.5 kW RF Amplifier $4,995 +
shipping and handling
## how much money do you want to spend ????
## A GG triode is the way to go. Forget the 2 x holer. If you need more HP,
you don't put
2 engines under the hood of your truck. 200 w of drive into a YC-156 will peg
a 10 kw slug,
and you can get a YC-156 for $200.00 to $300.00 200w into a 3CX-3000A7
will peg a
5 kw slug. No socket, and no parasitic suppressor required for the YC-156.
Used vac caps
are cheap. A 4800 vac 10 kva hypersil pole pig [120 lb, 1 cubic foot] will
run a YC-156
nicely. 1/4"-3/8"-1/2" copper tubing is dirt cheap at home depot. Gigavac G-2
vac relays
are cheap for hams. 6A10 diodes are cheap. HV 450 v lytics are cheap..esp the
2000-4000 uf
variety.
## You can beat Alpha, et all, at their own game, and get 6-8 X more power to
boot. You will get
30k hrs from a new 3CX-3000A7. Lowest imd tube, period. [-58 db pep]. Use a
PI net, with
a low tank Q..like 8-10..and it will be very broadband. A L-PI is used on
the upper bands.
## You can use the 225W CCS grid in the 3x3 as a dummy load for your XCVR.
Since the grid is
bonded to the chassis via a grid ring, the grid diss is actually a lot higher.
A simple grid fuse + cathode
fuse provides ample protection. A high power Glitch R + HV fuse provides the
protection in the B+ portion.
## I use the Array Solutions wattmeter for the hi-swr protection.
## Then you end up with the...'real deal'. The metering is simple. I use
separate grid/plate current
meter's.. and ditto with B+. You won't get this kind of satisfaction from an
Alpha, or any other
amp. Want QRP... use a 8877, or any of the other fine tubes out there. I
end up using vac caps
either way, so it's a moot point. Chinese 3CX-3000A7 / 3CX-6000A7's are
cheap... and will last
a lifetime. GS35B is a good tube too, no suppressor required either.
## Do you want a...'me too' shoe box on the desk ? There are plenty to
pick from.
Later... Jim VE7RF
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