[Amps] [Bulk] Re: 572B - News?

[Dave]

The service bulletin was in the bias system for the FL-2100B.   Improper
bias triggered instability.  There were not RF related changes.The FL-200Z
has a different bias system but I don't remember if it fixed the problem.
The problem does not exist in the 30L1 or the SB-200 .All the details are on
the Web.  I Svetlana's plate dissipation rating is 160 watts, just like the
572B.  Yes, the plates are smaller but they are also thicker and are made of
graphite like the original T160 (original nomenclature for what became the
572B.  I have a set of original ceramic base 572B in my 30L1 and they have
worked perfectly for over 5 years of daily use and the amplifier is stable
on all bands.  I wish I had bought a spare set back when they were current
production.  

Dave
W7VM


-----Original Message-----
From: Amps [mailto:amps-bounces at contesting.com] On Behalf Of Al Kozakiewicz
Sent: Friday, November 07, 2014 10:56 AM
To: amps at contesting.com
Subject: [Bulk] Re: [Amps] 572B - News?

Plus, if I recall, there was a service bulletin on the 2100 (not sure it it
applied to the Z variant) regarding the use of the Svetlana tubes.  The amp
needed a modification (probably to the parasitic suppression?) to use that
tube.

Al
AB2ZY
________________________________________
From: Amps <amps-bounces at contesting.com> on behalf of Carl
<km1h at jeremy.qozzy.com>
Sent: Friday, November 7, 2014 1:03 PM
To: David Harmon; 'Marcelo Cabral'; amps at contesting.com
Subject: Re: [Amps] 572B - News?

The Svetlana works OK but has a smaller anode and less dissipation. They
havent been made in several years now.

Carl
KM1H


----- Original Message -----
From: "David Harmon" <k6xyz at sbcglobal.net>
To: "'Marcelo Cabral'" <py1kr.marcelo at gmail.com>; <amps at contesting.com>
Sent: Friday, November 07, 2014 12:25 PM
Subject: Re: [Amps] 572B - News?


> Marcelo.....
> Try to find some 572-B made by Svetlana.......they are much better 
> quality.
> I have had several sets of them and I prefer them over the Chinese 
> mfgd tubes.
>
>
> 73
>
> David Harmon
> K6XYZ
> Sperry, OK
>
> -----Original Message-----
> From: Amps [mailto:amps-bounces at contesting.com] On Behalf Of Marcelo 
> Cabral
> Sent: Friday, November 7, 2014 11:18 AM
> To: amps at contesting.com
> Subject: Re: [Amps] 572B - News?
>
> Hi, Carl!
>
> Good news at the end!
> Sincerely, I will try a MP pair of these new tubes after January, but 
> I haven't big expectations about their reliability.
> But, if them survive at least one year, I must be finished the others 
> projects and be able for start this mod for GI7B. For today, I'll buy 
> some GI7B's from UR4LL, must be useful in a near future.
> Thanks everyone, hope to meet everybody in CQWW CW soon.
>
> Marcelo - PY1KR
>
> -----Original Message-----
> From: Carl [mailto:km1h at jeremy.qozzy.com]
> Sent: sexta-feira, 7 de novembro de 2014 14:52
> To: Marcelo Cabral; amps at contesting.com
> Subject: Re: [Amps] 572B - News?
>
> RF Parts will be taking new 572B orders in Jan 2015, Id rather wait 
> than hack up a perfectly good amp for an inferior tube.
> http://www.rfparts.com/tubes/tubes-572b.html
>
> Carl
> KM1H
>
>
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