Dessine-moi un tube

[castellu]

C'est fabriqué comment un tube ?

En image chez KR :



Magnifique savoir faire, j'admire ces artisans.

L'occasion de rapporter ici des documents sur la fabrication de nos chères ampoules...

B r u n o

[testi]

Nettement moins robotiser que chez Mullard à Blackburn  

[ZORGL]

Au travers des vidéos de CasseTespetitsLu (revival tube Thdg artisanalobobodiophile)  & de gitaneTesti  (working Mullard class heroes on a chain gang du tube de masse  ) je découvre totalement la réalisation en image de nos chères loupiottes !

....Désolé du léger hors sujet...



z0rgl ( White Punks & nodiophiles on dope des tubes nonos/ The Tubes  )

[castellu]

ça se passait comme ça chez Western Electric :

avant :
http://vintagetubeservices.com/we.htm

après :
http://www.westernelectric.com/history/tour02.html

B r u n o

[castellu]

et chez RCA ...

http://vintagetubeservices.com/page14.html

B r u n o

[testi]

Ballet de tubes chez Westinghouse

[lavoi]

Fabrication d'un tube chez un artisan fou
http://www.tubesusa.com/toshitubes.html

[testi]

Il y à aussi " fabrication d'une lampe triode" très artisanale ...

[castellu]

Fabrication d'un tube chez un artisan fou
http://www.tubesusa.com/toshitubes.html

En effet je me souviens d'un article dans la NRS sur ce foudingue...
Il fait les amplis qui vont bien avec aussi (en plus ses tubes sont beaux).

Sinon quand on voit les chaînes de fabrication artisanales de RCA ou Westinghouse, avec des mimines féminines au boulot le plus souvent, et que l'on écoute des tubes fait par ces personnes + de 60 ans après, c'est assez émotionnel comme dirait un pote...

B r u n o

[testi]

En effet je me souviens d'un article dans la NRS sur ce foudingue...
Il fait les amplis qui vont bien avec aussi (en plus ses tubes sont beaux).

Sinon quand on voit les chaînes de fabrication artisanales de RCA ou Westinghouse, avec des mimines féminines au boulot le plus souvent, et que l'on écoute des tubes fait par ces personnes + de 60 ans après, c'est assez émotionnel comme dirait un pote...

B r u n o

Je me dit un peut la même chose avec les fameux Victory Tubes, VT231 et autres de cette période ...difficile de trouvé plus fiables  

[lavoi]

[ En effet je me souviens d'un article dans la NRS sur ce foudingue...
Il fait les amplis qui vont bien avec aussi (en plus ses tubes sont beaux).

 

Il est parfaitement génial, un trésor vivant.

[castellu]

Mince, je n'ai pas trouvé l'article sur mes NRS

B r u n o

[castellu]

Vu sur le site Emission Labs, quelques considérations sur la structure des tubes :

Le filament

Of course, all tubes come to an end one day. For lifetime, directly and indirectly heated tubes depend on the same mechanisms, but in another order, and so the most occurring "death cause" is often another. Indirectly heated pentodes, like KT88 when constructed very good, will end their life by loss of vacuum, resulting from out gassing the plates (Anode). For KT88 and similar, this is the natural way to come to an end, if no quality issue occurred before during use. The occurrence and absorbing of very small fractions of gas gets visible by "eaten away" edges of the getter flash. Though such tubes apparently perform good, they are near the end of life and should be replaced. Once the getters can not absorb any more gas, the tube likely will self destroy during further use. Possibly damaging the amplifier, or blow the amplifier fuse. Self destruction can start with a short circuit between cathode and first grid. The short circuit can be permanent, or go away and re-occur soon. Next is severe off-bias and the tube will be severe overheated. The extreme heat may cause a vacuum leak along the pins inside the base. The tube is found with white getters one day, though it was working before. Such a tube is completely out of function, and will also not short circuit any more. In a push pull amplifier, this will now damage the other tube of the pair as well since it will try to draw the bias current for both tubes together. It must be said that indirectly heated tubes with "eaten" getter edges need to be replaced. (So the previous text only applies for KT88 and similar).

Good quality Directly Heated Tubes (DHT), like 300B normally have no out gassing problem. Their cathodes are more fragile, and such tubes must be run less hot by default. So a 40 Watt 300B is much larger size than an (appr.) 40 Watt KT88. Also cathode to grid distance is much larger with DHT tubes. So a short circuit will not take place at all. DHT with a gold grid (as we build them at EML since a few years now) will not have thermal drift away. So a severe overheating situation will probably never occur. With DHT, the filament's lower Emission and/or breakage normally ends the tube life. So great care should be taken not to underheat or overheat the filament, and switch on the tubes gently, possibly with pre-heated filaments. For this reason you can find sometimes indirectly heated tubes with +/-10% filament tolerance, whereas DHT have maximum 5% or no tolerance at all. Also for such triodes with 5% tolerance, the 100% value is the best. Since there is no considerable out gassing with EML tubes, the getter will stay good during the full lifetime. It means a DHT tube that is at the end of life, will not short circuit, and will not show a bad getter, but have a loss of bias current. However a loss of bias current is no reason to have the tubes checked, unless it is more than say 25%. Still such a tube can be "good" on a tube tester, and as long as the tube sounds good, you can use it.

Les fausses mesh plate

http://www.emissionlabs.com/html/produc ... e-mesh.htm

We have to point out here, we have seen sellers offering what they say "mesh tubes" from China, which are no mesh tubes at all.

The word MESH means woven Metal wire, and there is no other meaning. However this is a very difficult process for electron tubes, and Chinese factories do not have this process for this.

They now use metal plates such as from color TV pictures masks, that have many small holes lasered into it. Indeed on first sight it has the optics of a mesh anode. However this material does not have the mechanical damping proportions that is so typical for woven mesh. We do not say these are bad tubes, or anything like that. However we seriously protest against the use of the word MESH for this, because this is simple not what it is.

So with some sellers if they say it's mesh tubes, but they sell you punched plates instead, you are being fooled.

Parenthèse : on ne peut pas dire non plus qu'ils fassent des vrais mesh plate, avec la plaque donc constituée exclusivement de grillage, comme par exemple cette AZ1 TFK :

ou la 310A Western qui existe en mesh et aussi en punched plate :

La plaque EML, grillagée mais rapportée sur un "chassis" métallique :

La TJ mesh plate, qui est donc plus une punched plate avec perforations fines :

Les plaques carbone

We do not recommend the use of CARBON ANODES (CARBON PLATES) at Emission Labs.

At Emission Labs, we are conservative with following ideas about what we call "fun tubes". In China, at the moment, the main tube factory "SHUGUANG" is producing many such "fun tubes" for re-branding sellers. So you see interesting sounding brands come and go at the moment. Behind those brands is only a re-packing company, and what you get are nothing but SHUGUANG tubes with another jacket. So you get KT88 with black glass, faked mesh, or 6SN7 with Ceramic gold plated base, and other things that make the tubes cost more. The Chinese just produce what the markets desire, so everybody is happy. However it gets less nice, when they start "playing" around with anode materials on the cost of reliability, and tube specifications. What we think of fake mesh, you find above here.

Another trend we see is CARBON anodes (plates) for tubes that are not suited for this.

There is one golden rule with tube design, which professionals accept and understand. This rule says, do NOT try to invent something new, without looking back into history first. Tubes production was at it's top from 1930...1960 with HUNDREDS of factories producing tubes and 100.000 experienced and qualified design engineers trying to improve products and processes. it was THE MAJOR industry at the time, and world dominance of complete nations were determined by tube technology. In this environment, It can be observed that after 1940 NOTHING NEW was invented any more on the area of electron tubes. Simply nothing! The last break through was the RADAR magnetron tube, in 1938 by the British. Reason is not, these 100.000 engineers were not clever enough. Reason is simply, all technologies had been discovered and that was pretty much final. Whatever you try, it was done before by others. Only miniaturization came, and even that was on the cost of performance.

The use of CARBON Anodes was only done in Tungsten heated tubes. So the bright emitters like 211 or 845, these had CARBON tubes as an improvement. (In the beginning these had METAL anodes). For the bright emitter tubes, the good part is, the anodes can be soaked with getter material, and the great heat would in a way help to keep the vacuum good. Some carbon will evaporate, and come everywhere in the tube, mainly visible as a dark coloring on the glass. However since the almost white glowing filaments are so hot, there will be no carbon residue on the filaments. Though after long use the tubes look very "old", the ultra thin carbon layer, and coloring doesn't seem to do any negative to the tubes at all.

Today, the marketing made ideas of clever business men, have resulted in CARBON anode tubes, using modern BARIUM Cathodes. So not the bright emitter Tungsten Cathodes. Such tubes are sold as "better sounding". Well strangely, if better sound would result from such an idea, why did they not do so 50 years ago. Like, 100.000 Engineers must have been stupid.

From the experiments at AVVT, I can first hand say what the problems with such tubes are, and why this technology is not working good.

The CARBON evaporation get attracted by the Filament, and colors it dark. The filament should be cleaner than clean however, for good lifetime. Overall, with carbon contamination on the filament, such tubes have lower lifetime, and contamination starts to begin already after 500 hours. The temperature of a BARIUM OXIDE filament is not high enough to remove the carbon by evaporation. This is the main problem, and it can not be solved. The next problems, Nr2 is a matter of technology, and Nr3 is a matter of price.
There is NO monkey proof way to connect an electrical wire to the carbon. Historical tubes like the 211 and 845 used a shrink connection, which connection by definition has mechanical tension, whereas carbon is brittle. The monkeys here are the post companies. All you need to do is kick the box around, and you get micro cracks in the carbon, just where the shrink connection is. This will later on develop a whisker sound. (THE problem with Chinese 845, as we all know).
The really PURE and CLEAN carbon is simply expensive. To obtain this, you must out glow expensive (TUBE GRADE) carbon, which is very expensive. So the temptation has always been to use lower cost carbon (as used for radio batteries). This raw carbon costs almost nothing, and if you out glow this long enough, for several weeks you get useful material though still second class. However with today's energy prices, out glow it for three weeks is out of the question.
Conclusion:

Even if above points Nr2 and Nr3 can be overcome, point Nr1 remains. So for this reason you will never see a carbon plate tube with Barium Oxide filaments at Emission Labs.

.................

Intéressante mise au point d'un constructeur sur ses choix techniques, dans un marché très... concurrentiel..

B r u n o