tulk1 Posted January 10, 2017 Posted January 10, 2017 Figured my JCM900 post had run it's course before I posted these. Maybe not. Maybe I'm post trolling!!! Either way, these were in the JCM900 when I took a peek inside. Anyone got the scoope` on them?
notbillgelder Posted January 10, 2017 Posted January 10, 2017 Tesla history 1922 Company was founded in 1922 under a name Radioslavia Ltd. which was changed into share-holding company earlier in 1923 with shares of French company Comanie General. Its main concern was business and import of first radiotelegraph transmitters and receivers. There was a strong competition on Czechoslovakian market due to companies such as Philips or Telefunken. 1932 -connection with UK company Marconi Wireless Telegraph Co. Radislavia begun assembly of first radiorecievers from parts imported from UK. This start was successful which is documented as many transmitters build in Czechoslovakia. 1936 First transmitter electron tubes are being build. International situation caused need for small transmitting tubes for army and huge ones for maintenance of transmitters. Choice was put on Radioslavia, which was able to make first tubes already in 1936 but they were made under a name Marconi. This first generation of tubes were heavily influenced by Marconi designs of power triodes. They were made with outside copper anode cooled by water or air cathode made from pure wolfram and Isolating vacuum chambers were made from leaded glass. Typical type of those tubes is 150kW triode RD 150 YA.Through second World War no tubes changed thou some of the equipment was lost to fights. All the saved technology was moved to central Prague – Vrsovice. All of the remaining employees that came here had to reinvent the technology on the memories of old engineers and half missing documentation. They had to succeed so transmitter network in Czechoslovakia wouldn’t have to be shut down. 1948 After year 1948 Radioslavia changed its name and status into TESLA Vršovice. At the beginning they heavily focused on reaserch of new kinds of tubes. So new types of tubes were invented not only for radio network but even for newly emerging TV network in Czechoslovakia and other countries in Europe, later even for many countries in Afrika, Asia and Amerika. Power of those tubes merged form hundreds of watts to 150 Kilowatts. Isolation parts of vacuum chambers were firstly glass but in sixties came technology of Ceramics – metals. Cathodes from pure wolfram were partially replaced with Throated wolfram. Some of the types were equivalents for tubes from other manufacturers and countries but mostly they were OEM made for TESLA Hloubětín which made and researched new transmitters. Well known types of those tubes are RE 5 XN, RD 10 XL RD 70 VL, ZD 70 VL etc. Anodes were cool not only by water or air but also vapor cooling was put in place. Increase in production called for new spaces such as stores, research labs and assembly lines. It forced TESLA to make new franchises in Prague and all around Czechoslovakia. 1970 – 1980 Research of huge radio transmitters put TESLA Vršovice under pressure to make tube that is heart of those devices. This task was phenomenally huge for company that required new staff technologies research and manufacturing line. The final product was power triode full ceramics 250 kW RD 250 VM fallowed by line of ceramics tubes mainly tetrodes for TV transmitters or FM radio. Besides electron tubes portfolio of product increased in medical supplies and diagnostic devices for radiolocation – Betatrons and hydrogen Thyratrons. For IV. and V. Bandwidth power klystrons were made with the cooperation of research institute. TESLA Vršovice underwent a lot of management changes which were tightly connected with implementation of National Company TESLA. In seventies TESLA regained its position as Private company. 1980 In 1980 TESLA was connected with Research institute for Vacuum Technology in conclusion of trend of discontinuing ineffective research centers. This fusion took almost 10 years. 1990 In 1990 was TESLA Vršovice truly finally free. 1994 1994 – TESLA Vršovice transformed once again into Private limited company TESLA Vršovice Ltd. continued in a making and research of transmitting tubes, tubes used in industrial generators, Powerklstrons and vacuum interrupters. Product of TESLA went into most of the old stats of Soviet Union and Middle Europe. Our products came also into some parts of Africa and Amerika. Many old types of tubes were modernized and uses technology of ceramics isolating parts. New products as equivalents to old or discontinued tubes of other companies were made. Trend of acoustic amplifiers with tubes was followed. 2006 In 2006 TESLA Vršovice s.r.o. got new owners and was yet again renamed into TESLA ElectronTubes s.r.o. 2007 – 2008 On the verge of 2007 and 2008 production was moved into new places at Ricany u Prahy All the product lines have continued but research and capacity was increased. 2009 – 2012 Research and beginning of making of semiconductor middlewawe transmitters of line Radioslavia MWT of POWER 1 kW, 5kW and 10 kW so they could be presented and offered at IBC2013 at Amsterdam. 2013 -Cooperation on project KV MOB – making and research of special antenna for Army CZ. -Research of spark gaps for flight industry in cooperation of First Brno machine factory. -Begging of the research of 5kW triode for use in induction and welding plastics and 3kW triode for system Izodent and spectral analyzers. 2014 - Research of 35kW triode for woodworking textile and food making industry. -Research of 30kW tetrode for amplicon in HF generators for industry grade lasers with power up to 5 kW. Those lasers are used for metal working such as burning thick metal sheets or welding. 2015 -Beginning of the research of 22kW triode for application in HF generators in industry lasers for mettelcutting of power between 1 and 3.5 kW. 2016 Research of line of triodes ranging from power of 9kW to 17kW for HF generators for PVC welding and material drying. Slowly falling market with transmitting tubes due to digitalization of transition Made TESLA ElectronTubes to reevaluate their product portfolio. Company began to be oriented mostly at making of industrial tubes at the ceramics-metal basis used for generators of CO2 lasers and tubes for HF generators focused mainly on textile, food, woodworking and metalworking industry. Current trends in modernization of electro distribution network in Eastern Europe allows research of new types of vacuum interprets http://www.electron-tubes.cz/en/history
212Mavguy Posted January 10, 2017 Posted January 10, 2017 Don't get rid of those el34's. I have a pair in very good shape, they deliver a very nice, detailed sound, more detailed than my RFT's and Mullards. Lots of harmonics! The Tesla e83cc and ecc803s have a frame grid construction, resistant to microphonics and were built on the tooling they bought from Telefunken, formerly used to make the Telefunken ecc803s. That TFK tube type goes for incredibly stupid money nowadays. Tesla ecc803s/e83cc frame grid NOS go for 75-100 bucks a pop, the TFK's three to four times that.
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