There's Made in Germany stamped on it, isn't it? Most probably it was made at one of the RFT tube plants in former Eastern Germany (so called GDR).
Best regards!
Best regards!
Exactly. There were many of them, for instance Röhrenwerke Neuhaus or Mühlhausen, Oberspreewerk, Werk für Fernsehelektronik, Funkwerk Erfurt...
Best regards!
Best regards!
Well, after the West German major tube manufacturers shut down their plants in about 1975, any of them bought tubes from GDR's RFT and just relabelled them. I think this deserves some interest, as eastern tubes didn't have the best reputation formerly.
The OP's tube is easy to recognize 'cause GDR manufacturers used the same ECC81/EC92 plate structure also for their ECC82 and ECC83 double triodes, whereas West Germany's had that plate only in ECC81's and EC92's, whilst ECC82 and ECC83 had another, but again identical structure.
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The OP's tube is easy to recognize 'cause GDR manufacturers used the same ECC81/EC92 plate structure also for their ECC82 and ECC83 double triodes, whereas West Germany's had that plate only in ECC81's and EC92's, whilst ECC82 and ECC83 had another, but again identical structure.
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I could not in the slightest way have known this although my electronics education was mainly in that period of time : roughly between 1960 and 1975.
Very enlightening! Haven't tested it or anything yet. Came out of an old piece of test equipment. May be nice to keep for a conversation piece.
Thank you very much!
Thank you very much!
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Yes, keep it, despite of it's somewhat unusual plates 😉. Most probably it was made according to West German ECC83 standards, i.e. with bifilarly wound heaters, hence improved hum suppression in comparison with a plain 12AX7.
Best regards!
Best regards!