SB-200 users: a question.

[Bob, W5UQ]

572B's are much better than 811's. 
811's will destroy long before 572B's.

He's getting bad 572b's... buy new ones or get used ones from someone 
you trust... too many sell duds and weak ones just to get money...greedy 
people.

Be careful who you buy them from and 572B's are the  best choice, no 
question.
Bob W5UQ

-- 
W5UQ.com
QRZ.com 

A man in earnst finds means or if he cannot find, creates them.
Channing

Success needs help....as does failure.  And just possibly, about the same amount. 
Bob Hardie 10/87



 



Wilson Lamb wrote:
> Won't 811As run in that thing?  They are nearly indestructable and 
> you'll never notice a little powr loss. When I was a kid, I ran them 
> at 1500-1600V, zero bias, in a modulator for several years.  You'll 
> need some bias, I expect, but that's not hard.
>
> If you run a lot of CW, it would be good to add a grid leak, maybe 
> that you can switch in/out, and drive them into class C.  Your output 
> would be increased somewhat over the linear case.
> Wilson
> W4BOH
> ----- Original Message ----- From: "Kenneth G. Gordon" 
> <kgordon2006 at VERIZON.NET>
> To: <HEATH at LISTS.TEMPE.GOV>
> Sent: Monday, April 19, 2010 12:11 AM
> Subject: SB-200 users: a question.
>
>
>> Well...since I have had both my SB-200s, I have been
>> having considerable difficulty obtaining 572Bs that are
>> reliable and will output what they are supposed to for more
>> than about a month.
>>
>> I run them as I am supposed to, keeping the grid current
>> well below 100 mA, but they seldom last. I don't abuse
>> them, and run mostly CW. I never allow them to show
>> color.
>>
>> I am very seriously considering replacing my 572Bs with
>> 813s, or some other heavy-plate tube of about the same
>> physical height.
>>
>> What do others use? How long do they last in normal
>> service?
>>
>> I am NOT pleased... :-(
>>
>> Ken Gordon W7EKB
>>
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> Products bought, sold or traded here is the responsibility of the
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> for losses or misrepresentations of any kind.  Buyer beware!
>
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Products bought, sold or traded here is the responsibility of the
parties involved.  This list and the City of Tempe are not responsible
for losses or misrepresentations of any kind.  Buyer beware!

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This list is a public service of the City of Tempe, Arizona
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