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Message-ID: <34E0A2C7.EFE3AE9A@ibm.net>
To: <amps@contesting.com>
Date: Tue, 10 Feb 1998 13:56:07 -0500
From: Doug Person <DougPerson@ibm.net>
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To: Rich Measures <measures@vc.net>
Subject: Re: [AMPS] Contemplating Building of First amp
References: <19980206020922.AAA2135@[205.231.11.89]>
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To Rich and and everyone else who responded to my post: Thanks!
Rich, Thanks for your offer of some tubes. My concerns about the
5-150B are the 4KV needed to feed it and the possibility that someday
they may go soft and need replacing.
They seem well-suited to what I'm interested in doing otherwise.
Looks like an easy 700 watts out on SSB.
Having done a little research, I was wondering what you thought of
the 4CX400A. Looks to be able to deliver 600 watts with 2.5KV
on the plate. One 4CX400A is only a few bucks more than a pair of
572B's. I like the simplicity of a single tube. Fewer components
are required, saving a few $ and offseting the cost difference
from 572B's or others like it.
I also note that Svetlana now makes an 812 tube. Not sure how they
compare to 811's, but recall they are a hotter version of the same.
Had orginally thought to use 4 6KG6 tubes. These only require
1KV on the plate and I thought to build something like the
the DenTron GLA-1000B. Many of these little amps are lying around
dead and available for parts scrounging for next to nothing. This,
since 6LQ6's are going for $50 each, makes the little amp not worth
re-tubing. Just not sure what the 6KG6 is capable of in this kind
of service.
I am most interested in the 4CX400A, or perhaps there is another
tube even more suitable. The 4CX400A looks to need 2.5KV at 400ma
to deliver 600 Watts (ICAS). It is certainly more effcient than
811's or 572B's. Svetlana has a doc on their 4CX400A at
www.svetlana.com.
Is anyone aware of a project similar to this that I might reference
as a starting point? I have a lot to learn about power supplies
and output circuits, and I'm determined to learn it.
Thanks again,
Doug -- W4DXV
>I am contemplating a first attempt at building an amplifier. I am
>thinking of one that could produce a half KW (or more)on all bands from
>160 through 10 meters, be seriously rugged with a heavy duty cycle, and
>yet be made of parts that are readily available.
>
>I have been reading the posts to this reflecter and have been most
>impressed with the kind of knowledge possesed by several participants.
>
>It has become more and more difficult to find interesting projects with
>which to enjoy this hobby
amen
>(I've built so many antennas), that I thought
>assembling an amp would be interesting, educational, fun, and result,
>hopefully, in a very usable piece of equipment.
>
>I would sincerely welcome everyone's input. What type of tubes,
I have some unused Eimac 5-125B pentodes I will donate if you pay the
freight. The rating is 200mA each. The filament draws half as much
current as a 3-500Z -- 5v@7.5a. Although the 5-125B may be used in
Class
AB1 grid-driven service, I recommend g-g service. The socket is the
same
as for an 813, which is available at swap meets. In RTTY service, one
tube will put out around 240w max.. In SSB service, one can put out
around 380w max. . . At 4kV, the drive requirement is about 25w per
cathode. Less anode supply v means more drive needed. A 5-125B is
fairly exciting to watch doing it's job. It uses a tantalum anode. At
full throttle, you can read a newspaper by the brilliant yellow-white
light from the anode.
- Some amplifier design info is on my Web site.
www.vcnet.com/measures
cheers, Doug
Rich...
R. L. Measures, 805-386-3734, AG6K
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