Fake and Rebranded Tubes

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Απο το site του φιλου Jac Van De Walle

http://www.jacmusic.com/nos/images/Fakes/index.htm

 

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Σε αλλο σημειο του παραπανω site βρισκεται το εξης


Why TESLA KT88, is NOT JJ KT88!

The Czech Republic State TESLA electron tubes factory was split in several companies, during privatization. Here is as far as I can reconstruct what happened. Some parts manufactured those yellow color street lamps, and mercury light bulbs, etc. I don't know what happened to this part.
The part that made the Audio tubes, like EL34, ECC83 etc, was sold to Jan Jorgo, who owns now the JJ company.
The part that made the transmitter tubes, and some magnetron tubes was sold to Mr. Malinivic, who called this factory TESLA VRUSOVIC. He bough this plant including the buildings. They made some pretty interesting transmitter tubes, some had laser cut grids from a solid block of graphite. So they just blast away all graphite, until a solid part is left that is actually is as fine as a tube grid, with very fine "wires" of graphite. These are miracles of manufacturing. Just touch this grid, and it breaks. Once in the tube they are indestructible.

TESLA VRUSOVIC had found out, they would have liked to build a KT88 also, because profits were better than on transmitter tubes, but all tools were in the hands of JJ, so he had to remake them all, which he actually did.


HOWEVER.... it is not only tools that make a tube. They found that out the hard way. They lost most of the knowledge, lost unreplaceable machines, and happily fired what they thought were useless old man. Modern times were coming. Good-bye Lenin. They later learned these that KT88 senior tube experts can't be found, and they couldn't make (good) KT88 without them. When they realized what they had done, they couldn't get them back. I have visited that production line myself, in 2003, but that was after the loss of expertise, and it was in a dying condition. They were building the KT88 line up from scratch, re-furbishing broken tubes, etc. All if that was very hard to do, and actually what I saw was a big mess.

Getting back 25 years of experience, but from whom, and how? Questions.... questions... Many bad tubes were the result of these attempts.
There was from 2001--2003 some retro production of the TESLA KT88, with the blue logo. I had three charges of them, and the overall failure rate was 10% within the first six months use. From this the statistic calculations say you have 35% chances on ONE bad tube in a QUAD. As you can understand, this made this business not very pleasant to do.
LATEST NEWS: APRIL 2006 FACTORY PERMANENTLY CLOSED. This moves TESLA KT88 permanently to the Hall of NOS Tubes - END OF PRODUCTION - FINISHED - OVER AND OUT.

 

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Επισης προσφορα του JAC το εξης



[SIZE=+2]Why JJ tubes are not Tesla tubes.[/SIZE]
There is a common misunderstanding in the internet called TESLA-JJ tubes. I don't know which duck invented this word, but such tubes don't excist. There are TESLA tubes, and there are JJ tubes, both made in different factories, by different people, with different technologies. Only the machines are the same. The used materials definitely are not. For instance TESLA has used the cathodes from the former TESLA Rosnov factory, but this factory is closed now. So Tesla gets them somewhere else. Cathodes are elementary for tube performance.
May be you know that Yugoslavian "EI" ECC-series tubes are made on old Philips machines. This is EXACTLY the same situation, but I hear nobody talk about EI-Philips tubes. They are regarded something different, which is correct.
Until 1997, the world market prices of tubes of the ECC series were relatively low. There was enough NOS around. Many people thought this situation would allways stay that way, and the TESLA management thought so too.
The Russians sold NOS EL84 for 400$ per 1000, and from China you could buy good EL34 and ECC83 for increadible low prices, if you knew the way. It was b ythat time that Tesla decided to sell off their line of Audio tubes to JJ. In the last years, the TESLA ECC83 was sold for only 2Euro in OEM quantities, by company in Austria, who claimed to be their exclusive distributer. From this you can see that the factory price must have been very low. After selling off the audio line, TESLA went on making transmitter tubes, and other devices like vacuum capacitors, and military devices, which they considered more profitable.
So the TESLA ECC-series, EL34, and KT88 was out of production now. The machines were moved out of the building and re-enstalled at the JJ factory.
Unfortunally for TESLA, this was a big mistake. In the years after that, Ebay made the NOS prices soar, and today in 2004 they still rise 20..30% per year. NOS is practically unavailable in quantities. Russians and Chinese tube factories raise thier prices twice a year due to higher energy costs and higher cost of all kinds. It appears that JJ made a perfect buy!
Since most JJ tubes are mader with old TESLA tools, differences are small. They do use a different cathode, because the TESLA cathode factory in Rosnov is closed now. Both TESLA and JJ used to get their cathodes there. So NOS TESLA tubes have cathodes from Rosnov, and where JJ has their cathodes from today, I don't know. This is one difference.

Indentical tools are used



Another difference is in the part numbering. E88CC originally is a long life version with gold plated leads, but the TESLA version has only normal leads. In the below picture you can see this difference clearly.

Gold pin TESLA tubes.



The next differnce I noted, are some costs savings on the shielding. With this tube there is a shielding plate between the two triodes. With the TESLA tube, they did someting nice. The shielding plate was coated black, and is used to transport the heat out of the tube center. So is is used a cooling fin. This is great, because the center anode plate is already hotter than the outside anode plate.

Grey coated shield by TESLA
With the JJ tubes, exactly the same shielding plate is used as with the TESLA tube. Only JJ uses lower cost, untreated white nickel, so the cooling fin function is not present any more. This will give the old TESLA tubes a better lifetime expectation. In vacuum, only black material will radiate heat very good.

For the Czech Post, a GOLD GRID version was made. These are little jewels. Highly underestimated. Most of them have yellow printing. These are from the 1960's.

Here you see a close up of the gold plated grid bars coming out of the mica. So obviously they did not use just gold plated grid wire, they gold plated the complete grid after it was made. What a quality this is!

 

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Μιχάλη, να ανεβάσω καμιά και από μένα; Έτσι για σχολιασμό...

 

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Μιχάλη, να ανεβάσω καμιά και από μένα; Έτσι για σχολιασμό...

Φυσικα. :cool_4:
Γιατι ρωτας ?

 

[Costas Coyias]

 

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