Random observation on unboxing BeePre kit

[dave-tx]

Finally getting around to starting the BeePre, and had to comment...This is my first time holding a 300B in my hand, and my god, that is one beautiful tube.

[johnsonad]

Lol, they get better but the feeling is still the same. I've got tubes that I show guests just to see and feel the build quality.

[Chris]

Is it true that if you get oil or grease on the tube that it can crack when hot?

[Paul Birkeland]

Is it true that if you get oil or grease on the tube that it can crack when hot?

The glass used to make the tube would have to be extremely thin, or the tube enormously hot in order for that to happen.

(IE - this is not true)

[STURMJ]

This might be true of high output halogen lamps, used in microscopes, projectors, headlamps. The finger grease might cause heat to acccumulate at those oily areas, ant not in the others.  With the high heat these put off you get different expansions in the glass, causing cracking (maybe).  With tubes they have much thicker glass, not nearly as hot, and much larger ( they don't heat up as fast ).

[Chris]

Yes, sturmj says exactly what I have heard, but I just didnt know audio tubes are too  thick for that so thank you both... STILL, I will clean very well all my NOS tubes just in case...

[Doc B.]

Vacuum tubes are not halogen lamps. You want to keep fingerprints to a minimum because they can cook onto the surface over time and become fairly permanent. There is also a theory that the contaminants will migrate thru the glass over time and eventually get inside the glass. But I suspect the amount of time necessary would far exceed the time it takes for more plausible scenarios like intrusion of air into the envelope thru the pin seals.

A counter argument to being overly concerned about cleaning the glass is that the lettering on some very collectable tubes comes off very easily (read "ah shit" way too easy). If you wipe that Telefunken logo off the tube it looses some value.

[KevO]

So, if you 'add' a Telefunken logo does it increase the value?

My Pope tubes now read ope or maybe Dope.....

300B's are pretty cool looking. Now using carbon plate Sophia. Mesh plates are probably the nicest looking.

-Kevin

[Chris]

Yes, true Doc, thank you... I have teles also and I just give them a nice buff with a lens cloth making sure the logo is avoided... seems to be good enough..