Weird "holes" in getter

[Pentium100]

Hi,

I have noticed some weird "holes" in the getters of the power tubes (6N13S) of my amp. The holes are only visible if I hold the tube against light. I have not noticed such patterns on any other tubes, though I do not have any other big tubes in use.

Is this normal or a sign of some problem (too hot, too high voltage etc)?

 

[Damon Hill]

As long as there's no loose flakes or particles inside the envelope, and the color's still metallic silver rather than oxidized or burnt-looking, I'd say that was just the way the getter landed on the glass when activated.


--Damon

 

[franzm]

...too hot, too high voltage etc?

Or a electron (or even ion) beam impact pattern.

 

[wrenchone]

Maybe getter deposition over some debris left on side walls during assembly - minute mica flakes?

 

[kevinkr]

This is common in some of the Russian tubes I have, may have something to do with the getter cup design. (I am a big fan of Russian tubes of various sorts and have lots of some types.) It has not ever caused a problem with these tubes.