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14th Dec 2021, 8:14 am | #1 |
Heptode
Join Date: Jun 2019
Location: Oxfordshire
Posts: 719
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Home made valves
Apologies if this has been posted before, but came across this fascinating Youtube of a French guy that makes his own valves. Not only are the valves home made, but it appears his valve making equipment is also!
https://www.youtube.com/watch?v=EzyXMEpq4qw |
14th Dec 2021, 10:20 am | #2 |
Octode
Join Date: Jul 2011
Location: Leicester, Leics. UK.
Posts: 1,681
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Re: Home made valves
There's also this chap:
https://www.youtube.com/watch?v=oSgVGwqJ2Jk http://tubecrafter.com/index.html And there was somebody in Poland, on YT in Polish, https://www.youtube.com/watch?v=PjTaLsM6Hbo&t=398s I think this is the right video ... he posted on the American forum, but I lost the link. Way beyond my present capacity, but fascinating. |
14th Dec 2021, 12:21 pm | #3 |
Nonode
Join Date: Jan 2010
Location: North Somerset, UK.
Posts: 2,129
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Re: Home made valves
I think that the first link may have been posted previously, but some considerable time ago and well worthy of repeating.
Making the electrodes of a valve is not that hard, the main challenges are in glass working and achieving a high vacuum. |
14th Dec 2021, 1:09 pm | #4 |
Dekatron
Join Date: Apr 2012
Location: Wiltshire, UK.
Posts: 13,953
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Re: Home made valves
I wonder if anyone has tried home made valves using metal envelopes??
Brazed copper for the outer envelope / anode construction would be good from the heat dissipation perspective. Anyone got access to a turbomolecular pump
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14th Dec 2021, 1:44 pm | #5 |
Dekatron
Join Date: Feb 2007
Location: Lynton, N. Devon, UK.
Posts: 7,061
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Re: Home made valves
It would need good removal of brazing flux though, and thorough leak detection testing before building-up and attempting to pump-out. I can see the attraction of glass!
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14th Dec 2021, 2:48 pm | #6 |
Moderator
Join Date: Mar 2012
Location: Fife, Scotland, UK.
Posts: 22,801
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Re: Home made valves
Firing a getter in a metal valve must be rather inconvenient, so I assume they must be pumped all the way down?
Etch-clean parts to be brazed in an inert atmosphere, keep there while brazed under induction heat. No flux needed. David
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14th Dec 2021, 2:58 pm | #7 | |
Dekatron
Join Date: Sep 2007
Location: Oxfordshire, UK.
Posts: 4,310
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Re: Home made valves
Quote:
Cheers, GJ
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14th Dec 2021, 3:17 pm | #8 |
Dekatron
Join Date: Apr 2011
Location: Cornwall, UK.
Posts: 13,454
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Re: Home made valves
Construction of a 6K7 "metal valve" etc, page 2:
http://www.nj7p.org/Manuals/PDFs/Tub...RC-14-1940.pdf Also: http://www.r-type.org/articles/art-018.htm Lawrence. |
14th Dec 2021, 5:36 pm | #9 |
Guest
Posts: n/a
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Re: Home made valves
Looking at the 6K7 the "Batalum" getter is twixt two pins in this case anode to an unused pin, it wouldn't matter if it was an active pin, the short circuit is meant to be blown up anyway. I guess it is a heater surrounded by getter, heat up getter evaporates, big current the short disappears. Ingenious.
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14th Dec 2021, 5:52 pm | #10 |
Dekatron
Join Date: Apr 2011
Location: Cornwall, UK.
Posts: 13,454
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Re: Home made valves
It's not a 6K7 per se but it shows the typical construction of those types of metal valves of which the 6K7 is one, apologies for any confusion.
Lawrence. |
14th Dec 2021, 5:54 pm | #11 |
Dekatron
Join Date: Apr 2012
Location: Wiltshire, UK.
Posts: 13,953
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Re: Home made valves
I guess that you could maybe re-work and stretch out 12-volt 21-Watt car brake-light bulbs for use as 'directly-heated' filaments - running them off reduced voltage since you don't need them to emit visible photons. Could some high-emission coating [Thorium?] be electro-deposited on the existing coils to get the electrons flowing more freely? A directly-heated rectifier capable of delivering quite a few milliamps of HT should be possible this way.
Envelope-construction - remember the Osram "Catkin" valves from the 1930s. Laser-welded, water-jacketed stainless-steel envelopes would seem to be the 21st-century version. And what about making a triode along the lines of the UHF 'Planar' ones from the 1950s; flat cathode, flat stressed-mesh grid and flat anode should simplify the whole 'mechanical rigidity' thing. Sealing the lead-outs through insulators would be my big problem: glass 'eyelets' were the solution for the 1930s/40s RCA metal valves, but it had all gone ceramic by the time the likes of the 4X150A came on the scene. Though I did a week-long 'laboratory glassware' course at Uni, I can weld much better than I can 'blow' Quartz/silica or Borosilicate glass!
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14th Dec 2021, 11:06 pm | #12 |
Triode
Join Date: Jan 2011
Location: Bradford, West Yorkshire, UK.
Posts: 43
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Re: Home made valves
Search for "Glasslinger" on YouTube and you will find several decent quality videos of him making diodes, nixies and triodes, he seems to have all the right equipment on a small scale & he covers the failures too.
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15th Dec 2021, 1:32 pm | #13 | |
Dekatron
Join Date: Apr 2011
Location: Cornwall, UK.
Posts: 13,454
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Re: Home made valves
Quote:
Lawrence. |
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15th Dec 2021, 2:36 pm | #14 |
Hexode
Join Date: Jul 2004
Location: Paris, France
Posts: 346
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Re: Home made valves
Hi to all,
AlekZ from Poland has built a 7 tube UltraDyne radio using Audion lookalikes he built himself : https://antiqueradios.com/forums/vie...ef69cf5ed0fb88 Also is experimenting with CRT building: http://www.videokarma.org/showthread.php?t=273434 Built himself a Monoscope test pattern CRT tube: https://www-pwl-mikrokontroler-pl.tr...en&_x_tr_hl=en The chap's resumé: https://www-pwl-mikrokontroler-pl.tr..._x_tr_sch=http Best Regards jhalphen Paris/France Last edited by jhalphen; 15th Dec 2021 at 2:41 pm. |
15th Dec 2021, 11:14 pm | #15 |
Hexode
Join Date: Nov 2009
Location: Cambridge, Cambridgeshire, UK.
Posts: 489
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Re: Home made valves
Quite a few years ago I was lucky enough to watch Gerry Wells make a valve in his shed/conservatory.
He made it look easy. |
16th Dec 2021, 10:34 am | #16 | |
Guest
Posts: n/a
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Re: Home made valves
Quote:
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16th Dec 2021, 11:47 am | #17 | ||
Dekatron
Join Date: Apr 2011
Location: Cornwall, UK.
Posts: 13,454
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Re: Home made valves
Quote:
Here's what the tube manufacturer (RCA) says about it (Mag. page 318, 2nd Para.): https://worldradiohistory.com/ARCHIV...w-1940-Jan.pdf Lawrence. |
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16th Dec 2021, 1:12 pm | #18 |
Guest
Posts: n/a
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Re: Home made valves
Indeed,, just a thought...
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16th Dec 2021, 4:28 pm | #19 | |
Nonode
Join Date: Aug 2015
Location: Cambridge, Cambs. UK.
Posts: 2,196
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Re: Home made valves
Quote:
Martin
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16th Dec 2021, 5:31 pm | #20 |
Guest
Posts: n/a
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Re: Home made valves
Here https://hackaday.com/2016/01/09/buil...blinker-fluid/ is an interesting triode.
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