tubes

[David C. Hallam]

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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>   
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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