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In Reply to: Re: NO posted by Jim McShane on August 23, 2006 at 09:16:33:
OK, bad science! Lemme restate: The preponderance of evidence suggests no proven mechanism for aging within a adequately sealed vacuum tube.This is because glass to metal seals were perfected long ago and chemical reactions happen very slowly - if at all - in a vacuum. If anything is happening it would be happening outside the envelope. But, I'm open to ideas- what do you think would happen to "age" a tube in storage? And is this a continuous process or does it reach some sort of equilibrium? If so how long does it take to reach the equilibrium? And if continuous does this mean that "aging" will continue forever? If the later is true there should be some way to "measure" the aging using valves of known age whose construction changed little. Or conversely, to determine that age of a stored tube of consistent construction but unknown date (I'm trying to figure out how we could set up a "double blind" experiment.)
Again, I think not but am willing to explore the idea.
Generally I think the primary difference in new manufacture and that of the past is the loss of engineers, labor, and supply that "grew up" with the industry. You mention mica so I suppose that you are aware - at least according to my geologist friends - that most of the high quality easily exploitable muscovite deposits in the continental USA are long gone? Muscovite is a potassium aluminum silicate and not known - as best I know - to contain gasses. And I would assume that the muscovite was "baked out" before use but I could easily be wrong.
So, while we probably still disagree I'm open to any evidence that isn't based on subjective opinion cuz I love mangoes but really thing chocolate tastes nasty
. Rob
Follow Ups:
Hi, Rob. What preponderance of evidence? Would you mind detailing this evidence? Your "mango chocolate" nonsequitur stands as silent tribute to frothing confabulation - the sound and the fury!
Yes, glass-to-metal seals were perfected years ago, or as perfected as they can get.No glass-to-metal seal provides a perfect hermetic seal. They all leak albeit at an extremely low rate. But leak they do. Additionally, there is no such thing as a perfect vacuum, at least produced here on earth!
So what you actually have is a an extremely slow leak into a less than perfect vacuum. The internal getter flashing should handle these problems.
One cannot expect the internals of their tubes to be perfectly protected from the outside world. As a practical matter they are since we can look at NOS tubes that are 50+ years old that perform as they should even with less than perfect vacuum and seals.
Does this lack of perfection in vacuum and seals cause subtle changes in tubes that are decades old? Probably not, but who knows. I would not think, however that this is out of the range of possibilities.
Glass and or Vacum will only prevent outside elements from reacting. Most alloys will have atomic migration of alloying elements, as will any working of the metal becomes undone with time (ie rolling of hot or cold steel is work being put into the metal). This I know as having studies material sciences while at OSU Welding Engineering college. Other than very pure elements, such as graphite elements used in some tubes, all materials have some sort of entropy change. The rate will vary for a variety of resons but still can happen.
Tim
Tim,With all due respect your response is sorta "generic" - yes we are all subject to entropy - I'm quite "entropic" myself but this really doesn't answer the specifics of "entropic effect" on vacuum tubes. While I do subscribe to the "anything is possible" school I also retain a healthy skepticism where someone stands to profit from purveying a bit of "lore." And I've got thousands of NOS/UOS tubes - some of which I'm presently inventorying to sell - so I would actually stand to benefit should this prove to be true. But the proof is lacking so far .........
Rob
Hi there, Rob. I don't think your post really deserves any respect at all based on the "wise-ass" attitude it displays. I guess we are all aware, now, of the thousands of NOS/UOS tubes you possess. Taking inventory to sell? You wouldn't be priming the market with your comment, would you? Just exactly How would you benefit from an entropic effect on vacuum tubes? You contradict yourself in your own posting. You're sorta kinda mean spirited too, aren't you? Perhaps proof is lacking for the normal operation of the gray matter in your possession.
Elektron,Why is it "wise ass?" Do you argue that the statement seems "generic" and not specifically adressing any issue in question? And I didn't state that any tube sales I might may would benefit from "entropy" but instead a proven value in "ageing."
I'm not a tube seller just someone with more tubes than they are can possibly use! There is no "priming" as I expect to sell these to other tech's hobbyists that I already know.
And I find it funny that you accuse me of being "mean spirited" (a personal attack) when I've not done so with anyone who posts on this board and I don't mean to come off as such. Rather than attack me why don't suggest ways that I can get my message across "more gracefully?"
Hmmm, and if I seem "passive agressive" please provide examples - if I choose to be critical of something/someone I wish to be direct and those who know me have never described me a "passive" about anything
. I hope you do note that I mock myself often, I try to be amusing - even silly - sometimes, and try not to take myself seriously while I do take what I have to offer seriously. Lastly, as I've tried to address your points, how have I contradicted myself.
Rob
Time is the variable here and as of yet no one has pinned down how long it would take for yout thesis to occur. Could be 10, could be 1000 years
Who knows. The rate is slow, alot of variables will determine the rate of change, for example, temperature, strength of the vacum ie any gass in there, the material purity itself, etc etc etc.
Tim
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