[Boatanchors] Question: Old tubes with brown on glass near the getters

Bry Carling bcarling at cfl.rr.com
Wed Feb 2 06:30:22 EST 2011

Sounds like they have been overheated, and mayt be burned up.
That is a trait of 6L:6s that I always associated with bad tubes, or 
tubes that have been "rode hard and put up wet."

I repaired hundreds of push-pull 6L6  X2 and 6L6  X4 amps. 
On the other hand most of the work I did on guitar amps using 6L6 bottles 
was 30-40 years ago. 

On 2 Feb 2011 at 3:55, William Morton wrote:

Hello All,

I came upon a set of electronics that happened to have a pair of Amperex 
6L6GC tubes. The electronics were all working and the tubes test very 
good on my tester (Hickok 605A). Assuming I tested them properly, there is 
no issue with gas.

The interesting 'feature' of these tubes is the color of the flashing on the 
glass near the getters. It is some sort of rusty brown color around the 
edges of what is normally silver or silver/black.

Has anyone seen such a trait and know the cause(s)?

Thanks in advance for any comments.

Best Regards,


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