[AMPS] New 572B's needed Any thought of what Brand?
km1h@juno.com
km1h@juno.com
Fri, 5 Mar 1999 16:38:44 -0500
On Fri, 05 Mar 1999 08:18:02 -0500 Scott Gordon <kq8rp@primenet.com>
writes:
i
>The Chinese Star tubes require the automatic tuner in the transceiver
>to get above 200 watts output. Even with the transceiver tuner in
>line, they put out only about 700 watts. The Chinese tubes clearly
>are inferior. At least, this set has a problem.
The original buyer went on price only, not quality. There are Chinese
versions that equal or exceed Cetron.
>
>In the past, I have owned Heath SB200 amplifiers, also with Cetron
>572B tubes, and can attest to the consistent performance of those
>tubes from one to another.
>
>I can buy 4 Cetrons that are a known quantity. They cost more, and I
>don't really know who sells these any longer?
Richardson owns Cetron. Take it from there. They also helped to destroy
Eimac.
>
>I can save some dollars buying the Svetlanas. But to me, the
>Svetlana
>tubes may be just as risky as the Chinese tubes.
Svetlana is much worse than any others, stay away from them except for AM
modulators.
>
>Please answer a few questions for me.
>
>o I can buy more Star tubes and take a chance, but experience says
> that is what I would be doing. Please comment based on your
> experience?
>
>o Should I buy Svetlana tubes that RF Parts promotes?
I sell my own brand from a select Chinese factory. A full 1yr no
questions asked warranty. Got so pissed off at the other versions I
spent considerable effort doing it "my way"
I can sell you a guaranteed matched quad for $230 shipped. I challenge
others to "show the beef".
No magazine advertisements, no BS, my customers are mostly contesters and
other serious users.
>
>o Why should I feel comfortable that they have the same consistent
> quality as the Cetrons?
There are many competing factories and some US distributors have name
brands based upon price only.
>
>o Do you know of any reason Svetlanas would not work well in the
> Clipperton L?
Do you have enough time for me to answer that ?? Untamed prasitics are
just the first reason. I was a Svetlana dealer, no longer.
>
>o Should I expect the Svetlanas to be as good as the Cetrons?
See above.
>
>o Anyone else using the Chinese Star tubes, but do you have any
> experience that will help me understand them?
Star is an entry level brand, also privately labeled by some distributors
selling price only.
>
>o What about this talk about a matched pair? Is it worth the extra
>$$$$????
In the Clipperton L it can be an important issue. In a 2 holer, probably
less important.
>
> Supposedly a matched quad, the Chinese 572B tubes were marked with
> handwritten figures of 103, 125, 126, and 131. By itself, the one
> marked 103 produced 30 watts out for 100 watts in and clearly has a
> serious problem. The other three each produced 200 watts when
> tested one at a time in the same socket. All the Chinese tubes,
> either together as a quad, or one at a time, required the
> transceiver antenna tuner to be used.
Unknown markings and probably based upon a static test only, if even that
much. I have purchased/evaluated a few brands that the markings show no
bearing upon matching, etc.
>
> The old Cetrons in the same one-at-a time test situation offered
>250
> watts, 250 watts (requiring the tuner), 350 watts and 350 watts.
>
> Why would 2 year old Star tubes have such a bad input impedance as
> to require an antenna tuner between them and the transceiver?
Several reasons. I could test, evaluate and mark any that you wish to
send...any brand.
I have a modified Clipperton L and SB-200 here that I use as test
platforms.
>
>o Besides the lower output and the requirement for the tuner, is
>there
> any problem running the Clipperton L with the 3 Star 572Bs that
>have
> reasonable output?
No problem except the slight loss in output C and keep the drive below
100W.
>
>Thank you in advance for your assistance as you guide me in my
>probable purchase of 572B tubes. Thanks Scott KQ8RP
There are a few other simple mods to improve the L performance, I can go
into that later if there is enough interest.
73 Carl KM1H
>
>
>
>
>--
>FAQ on WWW: http://www.contesting.com/ampfaq.html
>Submissions: amps@contesting.com
>Administrative requests: amps-REQUEST@contesting.com
>Problems: owner-amps@contesting.com
>Search: http://www.contesting.com/km9p/search.htm
>
>
___________________________________________________________________
You don't need to buy Internet access to use free Internet e-mail.
Get completely free e-mail from Juno at http://www.juno.com/getjuno.html
or call Juno at (800) 654-JUNO [654-5866]
--
FAQ on WWW: http://www.contesting.com/ampfaq.html
Submissions: amps@contesting.com
Administrative requests: amps-REQUEST@contesting.com
Problems: owner-amps@contesting.com
Search: http://www.contesting.com/km9p/search.htm