tubes

[David C. Hallam]

David C. Hallam wrote:
> Jack Schrader wrote:
>> Need some help on tubes.
>>
>> My sx101a lost part of its hearing and selectivity and when I checked 
>> the tubes I found that the 12BY7 was weak. I replaced it with one 
>> that tested better along with a different 12AT7 and it seems to work 
>> much better.
>>
>> My question is this. Is there one brand of tube, namely the 12BY7, 
>> that is better then another and the same goes for the 12AX7 and 12AT7?
>>
>> I have never paid particular attention to what brand of tube I use.
>>
>> Tnx & 73
>>
>> Jack
>>
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>>
>>  I should have said consistant difference between brands.  There may 
>> be a difference between individual tubes but it would be rare to find 
>> a consistant difference between bands
David
KC2JD/4
> Just because a tube is marked GE, RCA, Sylvania, etc., doesn't
> necessarily mean they made it.  Tube manufacturers geared up for long
> runs and would make tubes for a number of different suppliers during a
> run.  For the miniature type tubes it is rare to find any difference
> between brands.  For any given type tube there may be improved versions,
> i.e., 6AU6, 6AU6A, 6AU6W, 6AU6WC, etc.
>
> David
> KC2JD/4
>
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>

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