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RE: Effect of cold on tubes/valves

PostPosted: Fri Dec 09, 2005 9:00 pm
by blues power
[updated:LAST EDITED ON Dec-09-05 AT 04:01 PM (EST)]sounds like he heated up and burned the socket.
loose conntection=high resistance. high resistance=heat
heat=melting pastic

RE: Effect of cold on tubes/valves

PostPosted: Fri Dec 09, 2005 9:30 pm
by jeffl
Maybe checkin' yer tubes to make sure they're in tight ain't such a bad habit to get into....especially if you're switchin' back and forth at all.

RE: Effect of cold on tubes/valves

PostPosted: Wed Dec 14, 2005 4:38 pm
by blues power
any truth to this:

i heard you should never touch tubes with your bare hands cus the oils will cause heat spots and burn up the tubes?

others tell me they pull and replace tubes all the time with there fingers and have no probs at all.

RE: Effect of cold on tubes/valves

PostPosted: Wed Dec 14, 2005 10:29 pm
by bosco
I don't think there's any truth to that BP. I've been pulling them with fingers for years with no adverse affect.

I surmise that tale started when someone pulled a hot tube with a rag or glove to avoid burning their fingers and someone else misconstrued it as a finger oil deterrent as with halogen light bulbs.

Bosco

RE: Effect of cold on tubes/valves

PostPosted: Wed Dec 14, 2005 11:00 pm
by jeffl
The guy who owns the music store where I buy most of my stuff cautioned me against pulling tubes with oily fingers,but I don't know if he really knows anything about that firsthand, or if he was just told that by someone years ago. In general,the guy is extremely knowledgable,owns his own sound gear,and does sound for high school and civic choral and instrumental concerts,as well as for touring bands that use auditoriums around here. He also is a blues guitar virtuoso who has gigged for around 35 years. You would think that a little googling would turn up some discussion of this.... At any rate, I've pulled my tubes with a cloth since he told me that,lol.

RE: Effect of cold on tubes/valves

PostPosted: Thu Dec 15, 2005 2:07 am
by nhslim
The tube radio in my Buick died out in the cold and it's only 49 years old.

RE: Effect of cold on tubes/valves

PostPosted: Thu Dec 15, 2005 2:59 am
by ricochet
[updated:LAST EDITED ON Dec-14-05 AT 10:00 PM (EST)]It's a total myth about touching tubes with bare fingers being harmful to the tube. There is no factual basis to that whatsoever. As noted, it's true of quartz-halogen lamps. The reason there is that salts from perspiration, not oils, combine with quartz at highly elevated temperatures to produce glasses that expand thermally at different rates than pure qurtz, which can lead to fractures. No such effect occurs with glasses used in tube envelopes at tube operating temperatures.

Go to http://tubesandmore.com/ and get a reprint of one of the last RCA Receiving Tube Manuals, I believe it's RC-31. There's lots of good information in there about tubes in general, along with data for most of the commonly encountered types. None of the old tube manuals or electronics books had any caution about handling tubes with bare fingers in them, and I can tell you from direct observation that professional TV and radio repairmen routinely handled them that way.

In fact, the (nearly entirely female) workforce that assembled tubes worked bare handed, as gloves would've unacceptably hindered their manual dexterity. Certain tubes that used very fine grid wire suffered clusters of failures that were traced to being assembled by women on their menstrual periods, which apparently caused some detrimental effect on their fingers' perspiration, resulting in unacceptable corrosion of the ultra-fine wire. Due to the well known effect of women together in confined spaces becoming synchronized, they'd actually have to shut down those assembly lines for several days each month. But they didn't cause any problems with the glass.
:)

(That's not out of a tube manual. I got that from some of the retired guys who designed and produced tubes, on the Tube Collectors' Association mailing list.)

"A cheerful heart is good medicine."

RE: Effect of cold on tubes/valves

PostPosted: Thu Dec 15, 2005 2:32 pm
by jeffl
Geez,Rico..we know we can normally count on you for some technical direction,but the part about the synchronization effect of assembly lines on womens' cycles was really moving the bar up! If I'd have known that kind of stuff when I was a kid, I would have tried to get all my 5 sisters synchronized so I didn't have to put up with somebody's mood cycles all the time. My mom wouldn't let my sisters talk about their periods with me or my dad around, so I was left to guess most of the time.

RE: Effect of cold on tubes/valves

PostPosted: Thu Dec 15, 2005 2:36 pm
by ricochet
Some men will tell you that women leave you guessing most of the time in any case.

"A cheerful heart is good medicine."