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Telefunken tube codes

vendo81

vendo81

AK Subscriber
Subscriber
I've read the charts that give the codes on Telefunken tubes for dating, but have a couple questions for the experts out there.
I've read where they didn't use the letter "J" but have found several used ECC83/12AX7's with codes of "JO" and "JQ". I've also have a Tele 12AT7 I pulled from a oscilloscope with the same "JO" code.
Could this be a marking from a manufacturer that used Tele tubes? The codes are in the same location on other ECC83's that are listed in the charts. I know they are genuine tubes as years ago I had pulled several ECC83's to test, that had the "JQ" code, from a Marantz preamp my Dad hadn't used since the early 70's. Whats with that?? Marantz coding?

I also have several Tele ECC83's that came from a piece of medical equipment that have red or blue dots and the numbers "211" and "238" on top. I'm thinking the dots mean they were select tubes but what about the numbers on top? They are missing the usual date codes as well :scratch2:
 
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I also have some red dot Tele 12AX7s out of EEG amplifiers and was told they are hand picked ultra low noise. Given the amplitude of an EEG signal, I'd have to agree.....
 
Here are some of the tubes in question. Yes they are printed on the tubes....OEM codes? The photo with 2 Teles have a JO and JQ code. The "Fisher" labeled Tele 12AX7's came from a unrestored 400 I bought years ago.
 

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Just remember the best way to identify tubes is by internal construction...Telefunken printing is notorious for coming off easily!
 
Yeah, most of the writing on my Tele AX and AT7's went away long ago.
The only way I can identify them now is by the construction.
 
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