5965 Telefunken tube U mh CO label ?

[dunavko1]

5965 Telefunken tube

Does anyone know what the markings U mh CO below the TELEFUNKEN 5965. I noticed when testing this type of lamps that are more balanced and less reinforcement deviation between triode, as if they were chosen in relation to the classic TELEFUNKEN 5965. In this way 5965 mh CO is slightly different structures and different sounds. Translation from Google's and such.

 

[dunavko1]

As you can see in the photo to the left is a lamp marked The CO mh, have both ribed plate, holes puncturing two holes are the same - 3 holes, anode structure is not the same outwardly.
Mali on Geter is the same, there is one carrier.

 

[Kay Pirinha]

Hi,

I think, »U« marks the TELEFUNKEN Ulm plant yout tube probably has been made at. »mh CO« perhaps is the badge number.

Best regards!

 

[dunavko1]

I guess that's the mark signified technological difference between the classical and the 5965 lamp with U mh CO. Somehow it reminds me of the CO carbon monoxide, but what will it in the tube.

 

[Sorento]

U = Telefunken production site: Ulm, Germany
mh = date code: December 1957

entire table: Fertigungsdatum Röhren: Telefunkencode zeigt Fertigungsdatum

 

[Sorento]

some more historical data:
these 2 big pdf files list each and every tube ever produced by Telefunken and their actual production volume year by year, German thoroughness to the decimal point ...

http://www.radiomuseum.org/forumdata/upload/tfk_fertigung_teil_1.pdf
http://www.radiomuseum.org/forumdata/upload/tfk_fertigung_teil_2.pdf

according to pg.68 your 5965 was one of 43,765 manufactured in business year 1957/1958 (or one of 9,583 in 1956/1957 which was the 1st year of production of this type, can't say 'cause business years ran from october to october)
maybe your specimen is from an early run ...

a combined total of 286,699 were made until 1967