Hoffman Amplifiers Tube Amplifier Forum

Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: plexi50 on June 07, 2015, 06:13:15 pm

Title: Telefunken Date Code's
Post by: plexi50 on June 07, 2015, 06:13:15 pm

I have (3) Telefunken ECC83 / 12AX7 and (1) 12AU7 with the following letters and numbers on them.
Does anyone know the date these tubes were made?

12AX7 / B io O1

12AU7 / B hm 25

I have looked online but dont quite understand what there saying. The 2 digit code is pretty self explanitory. But after that i get lost.

Title: Re: Telefunken Date Code's
Post by: VMS on June 07, 2015, 06:51:05 pm

If we go with the info on this page:

http://tctubes.com/telefunken-date-codes.aspx (http://tctubes.com/telefunken-date-codes.aspx)

The way I interpret the code is
 
B io 01 = Manufactured in Berlin - May 1963 (or could be 1961) - internal number is 01

B hm 25 = Berlin - Ferbruary 1963 - internal number 25

Title: Re: Telefunken Date Code's
Post by: plexi50 on June 07, 2015, 07:00:57 pm

Thanks VMS. I am looking at that page now and am starting to get it.