Quote:
Originally Posted by maxhifi
Of course, I didn't answer the actual question. The grey coating inside of tubes is RF shielding, it's used on power tubes which were designed to be used at RF frequencies. Some audio tubes like the 6V6GT have it because they were dual rates for RF use too.
I agree it does tend to make tubes a bit uglier, but even the famous GEC KT66 has it
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Neat. Guess that must be the answer then and that makes sense. I can't help but think I remember seeing a few tubes that were not RF related that had that coating too though
