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Re: [Amps] SB-200 DATA

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Subject: Re: [Amps] SB-200 DATA
From: "Tom W8JI" <>
Date: Thu, 19 Jul 2007 10:08:23 -0400
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> I buy around 50 a year and many still have original 
> 60's-70's date code
> tubes and put out full power. I dont think that you will 
> ever see an
> Ameritron or Alpha running that long on original tubes; 
> they push them a lot
> harder

That life part is true, but the reason you give is not.

The fact is today we cannot buy tubes that are anywhere near 
as good or reliable as those made back in the 60's and 70's. 
Around the late 80's it really all started falling apart. In 
the mid to late 80's 8877's from Eimac were nearly all bad 
brand new (tube failures in MRI equipment nearly put ETO out 
of business) and Richardson's swallowed up Cetron and the 

When Ameritron started producing the AL-572B they made a 
mass purchase of Svetlana 572B's, and the majority of new 
tubes were bad (and old) right off the shelf. The only 
alternative, largely due to Richardson's swallowing up all 
the manufacturing and pricing 572's out of reach, were 
Chinese tubes. The Chinese tubes were tested only at 1500 
volts or so and a few hundred watts, and the glass and other 
materials were far substandard to the old Cetron's.

I can take 35 year old Cetrons that have been sitting up on 
a shelf and the majority high-pot to 8 or 9 kV, but about 
50% of brand new Chinese 572B tubes fail at 5kV or less.

The real truth is no matter how you run most modern tubes, 
the life on average won't be anywhere near the life of tubes 
before all the people who knew what they were doing retired 
or got fired.

The problem doesn't stop at the food supply, anything that 
requires extraordinary care (like tubes) isn't as good as it 
was. That's the real reason.

73 Tom 

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