Hi,
All it involves is hanging the tubes on the vacuumpump for days in a row so that all remaing gasses have disappeared.
If you don't have any barium and strontium ions left, no new ones can be created hence no useful life for that tube.
The experiment was done in the Philips labs and was talked about in an addendum to Audio & Techniek, a long defunct Dutch audio magazine.
The article is an interview with Philips engineer van Mossevelde in the presence of Ed de Jong ( Audio Note NL, Audio Innovations, etc.), Menno Spijker, Guido Tent (a member of this forum), Peter van Willenswaard (technical editor pro Audio), Eelco Grimm and John van der Sluis ( editor Audio & Techniek).
Titel: Audio Discussions, Buizen: fabricage, levensduur, gebruik.
AD4 page 10, person speaking Ir. van Mossevelde.
Cheers,
All it involves is hanging the tubes on the vacuumpump for days in a row so that all remaing gasses have disappeared.
If you don't have any barium and strontium ions left, no new ones can be created hence no useful life for that tube.
The experiment was done in the Philips labs and was talked about in an addendum to Audio & Techniek, a long defunct Dutch audio magazine.
The article is an interview with Philips engineer van Mossevelde in the presence of Ed de Jong ( Audio Note NL, Audio Innovations, etc.), Menno Spijker, Guido Tent (a member of this forum), Peter van Willenswaard (technical editor pro Audio), Eelco Grimm and John van der Sluis ( editor Audio & Techniek).
Titel: Audio Discussions, Buizen: fabricage, levensduur, gebruik.
AD4 page 10, person speaking Ir. van Mossevelde.
Cheers,
Hi,
# 14 I don't have a copy myself but you can also find it in:
Selection De L'Audiophile, Tome 1: L'Electronique, page 88 and onwards.
There may be a chance that this can still be backordered, the publishing house is " Editions frequences" Paris.
Otherwise the first series of issues can be ordered on CD-R here:
CD.
Cheers,
# 14 I don't have a copy myself but you can also find it in:
Selection De L'Audiophile, Tome 1: L'Electronique, page 88 and onwards.
There may be a chance that this can still be backordered, the publishing house is " Editions frequences" Paris.
Otherwise the first series of issues can be ordered on CD-R here:
CD.
Cheers,
Valve and tube manufacture
The way a valve is made, is a rather interesting story, First all the parts are assembled and the bulb evacuuated This phase complete, the cathode must then be activated, The materials of which its coated are Thorium and Barium Carbonates, and maybe some other rare earth element carbonates.
The cathode is activated, by heating-slowly, which liberates the carbon constituants, in the form of CO2 gas which is pumped off, At this time, care is needed not to let the pressure rise above a set level, this is why the cathode is activated slowly.
When this phase is complete, the cathode is then coated with Oxides, which must now be converted into the free-metal in suspension in the oxides, This is done by heating to around 20% over-temperature, for a set amount of time.
This done, the various electrodes are induction heated to release the occluded gasses in the metal surfaces, All the while, the Vac pumps are still going.
Finally, the bulb tip-off is sealed and the getter fired to mop up.
Then its on to testing etc, and burn-in for certain valves.
The way a valve is made, is a rather interesting story, First all the parts are assembled and the bulb evacuuated This phase complete, the cathode must then be activated, The materials of which its coated are Thorium and Barium Carbonates, and maybe some other rare earth element carbonates.
The cathode is activated, by heating-slowly, which liberates the carbon constituants, in the form of CO2 gas which is pumped off, At this time, care is needed not to let the pressure rise above a set level, this is why the cathode is activated slowly.
When this phase is complete, the cathode is then coated with Oxides, which must now be converted into the free-metal in suspension in the oxides, This is done by heating to around 20% over-temperature, for a set amount of time.
This done, the various electrodes are induction heated to release the occluded gasses in the metal surfaces, All the while, the Vac pumps are still going.
Finally, the bulb tip-off is sealed and the getter fired to mop up.
Then its on to testing etc, and burn-in for certain valves.
Apparently they moved again and I quote.
http://www.audioasylum.com/audio/tubes/messages/137022.html
Does anyone know if this is indeed the case?
Not that I really care. Would never be able to really afford the WE 300B's.. But that would be quite a shock for some..
Cheers,
Bas
Hi,
Hmmm...Can't confirm this other than observing the obvious: they're way behind schedule...
The writing was on the wall in 1988 already and with the undercutting of the market by the Russian and Chinese productions this was to be expected.
If it were me, I'd remake those famous little small signal tubes like the WE317A and such and than bank on that.
Errr...not at at 900 $ a pop of course.
Cheers,
Hmmm...Can't confirm this other than observing the obvious: they're way behind schedule...
The writing was on the wall in 1988 already and with the undercutting of the market by the Russian and Chinese productions this was to be expected.
If it were me, I'd remake those famous little small signal tubes like the WE317A and such and than bank on that.
Errr...not at at 900 $ a pop of course.
Cheers,
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