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I found this Tung-Sol 12AX7 in a stash of tubes I purchased this week.
This is definitely a first for my collection. I have never seen any tube with a copper getter.
Rare?
Semi-rare?
Kinda rare?
Perhaps more rare than a Beanie Baby?
Your interest may vary but the results are the same (Byrd 2020)
I can't compete with the dead. (Buck W. 2010)
Cowards can't be heroes. (Byrd 2017)
Follow Ups:
I've looked at a lot of vintage Tung-Sol 12AX7, and have never run across one with a copper getter wire. I'd say it is a rarity. It definitely is a Tung-Sol style, mounted on a wire "stem" and with the characteristic down-angled bend. It appears to be an early version, and the plate "tabs" (portion of the plate that protrudes through the mica spacers) are cut flat like their earliest 12AX7. I'd guess it is from the mid-'50s or earlier.
Tube producers experimented a lot in those days.
If it WERE a getter, and reacted with OXYGEN, I'd expect it to turn GREEN. the photo is of a beautiful, unreacted copper.
Also? Copper Oxide is a SEMICONDUCTOR and as such was used in multi-plate recitifiers 50 or more years ago....when selenium rectifiers were 'king'....
Too much is never enough
Please forgive me. I know you already know this but the copper metal part is not the getter. It's just some metal that holds the other metal part that held the getter before it was flashed. The silver substance on the inside of the glass tube is the getter.
Again, please forgive me.
Tre'
Have Fun and Enjoy the Music
"Still Working the Problem"
Ok....getter holder.Silver - getter flash.
Your interest may vary but the results are the same (Byrd 2020)
I can't compete with the dead. (Buck W. 2010)
Cowards can't be heroes. (Byrd 2017)
Edits: 07/27/21
Thank you.
Tre'
Have Fun and Enjoy the Music
"Still Working the Problem"
Someday I'll run across, again, an article in a 1940s "Electronics" magazine that explains the why, how, when of the tube getter. Very informative.
If I find it in my hard copy, I can provide a link the the magazine issue online.
Your interest may vary but the results are the same (Byrd 2020)
I can't compete with the dead. (Buck W. 2010)
Cowards can't be heroes. (Byrd 2017)
I'd like to read an article about how tube manufacturers make this particular decision. I have a number of 9-pin minis with no getter flash at all. They seem to work OK, but it bothers me.
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Buy Chinese. Bury freedom.
Getter IMPROVES the vacuum of the tube. It's that simple.
IF they could get a sufficientyly high vacuum before sealing? I don't think they'd need a getter.
But OTOH? The matierials used in the constructin do what's called 'outgas' which in vacuum terms is the emission of reactable gasses into the vacuum
And because the restricted shape of a tube does not 'pump down' as well as a large, open volume, it is difficult to get a tube TO a respectible vacuum.
Viscous flow resembles the flow of water. Knudeson flow is more......randomized....and Molecular flow is when air molecules strike the 'walls' more often then interacting with other gas molecules.
The last is where getters come in. A reactive atom bounces around the interior of the tube and is TRAPPED in a reaction with the getter.
I've worked on vacuum systems which took HOURS to reach ultimate pressure....This after being heated......pumped THAN cooled. At the TOP of what was called the Pumping Stack, there was a Cold Trap consisting of a thimble filled with liquid nitrogen. Many Volitiles 'stuck' to that and improved vacuum level and purity.
Too much is never enough
Any chance that they have pill getters?
Tre'
Have Fun and Enjoy the Music
"Still Working the Problem"
You're probably right. It doesn't make sense that they wouldn't have any getter at all. One type I'm thinking of is the clear top 5755, but there are others. I'll try to remember to take a second look next time I'm digging around in that part of the stash.
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Buy Chinese. Bury freedom.
I was wrong. It might be the first time.It's in the 1950 issue.
Getter Materials for Electron Tubes
Electronics - October 1950
Starts at page 80.Link to master page below.
Your interest may vary but the results are the same (Byrd 2020)
I can't compete with the dead. (Buck W. 2010)
Cowards can't be heroes. (Byrd 2017)
Edits: 07/27/21
Gettering appears to be a complex topic. Like many processes, there are multiple layers of technology just under the surface.
Wasn't aware of that archive. It's kinda sad, a reminder of past accomplishments and leadership, now mostly gone.
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Buy Chinese. Bury freedom.
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