6C33

[Bigun]

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[Alastair E]

At 'End Of Life' --3000 hours plus if used well within ratings,--the Cathode-emission goes below that needed to supply sufficient current for the circuit to work properly!

What you mean I think, is what happens when a 6C33 isnt burned-in properly and used 'raw' and goes bang!

Normally a destructive flashover/arc occurs which strips cathode material off the cathode, liberates gas and causes even more arcing to take place!

A Properly burned in 6C33 is quite happy up to 300 volts plus on the plate....
--Not that I run them at this high voltage, but they are more than happy with 150-200V on the plate, which is where I run 'em....

Also, I NEVER 'pre-heat' any tubes. Its FULL +B at switch-on as well as heaters. Never had a problem with Any tubes doing this....
Several hundred Million Tubed TV sets over 50 odd years Cant Be Wrong IMHO!

 

[tiefbassuebertr]

Bigun, Thank you for this insightful information

At 'End Of Life' --3000 hours plus if used well within ratings,--the Cathode-emission goes below that needed to supply sufficient current for the circuit to work properly!

What you mean I think, is what happens when a 6C33 isnt burned-in properly and used 'raw' and goes bang!
Normally a destructive flashover/arc occurs which strips cathode material off the cathode, liberates gas and causes even more arcing to take place!

Good explanation - thanks.

 

[tiefbassuebertr]

There are a lot of suppliers:
6C33 | eBay
Hard to say for me, where I can order at best.

Which companies produces still currently this tube model ?
And from where I can expect in this days the highest possible quality standart?

A friend need a new set-up in the next months for his OTL model "GM-20" from the Italian brand GRAAF.
Thank you for advices.