Telefunken C3M data

[Hearinspace]

On the Telefunken C3M data sheet Page 80 (fourth page of the file) for the plate voltage they give Ua = 220 u. 60V . It's the only one of the three curve pages where plate voltage is given this way. Does anybody know what it means?
Thanks

[tyo94]

Maybe you can ask Jac van de Walle at Jac Music. He knows a lot about this kind of tube

[radiostar]

I tested them in my experimental chassis with 220 V Ua, -4V Ug1 and 150V stabilised on G2 ... Hope it helps ...

[SY]

The u stands for "und" ("and"). They show two curves, one at 60V on the plate, one at 220V on the plate.

[Hearinspace]

That's the last thing I expected. Strange they wouldn't have used an ampersand or something. Und is only one character longer than u. , not worth the effort, and likely not something you'd ever see on an English data sheet, at least not in the land of the Red White a. Blue.

Also interesting to see on the graph how much more influence G2 has. This is my first adventure into the land of pentodes and didn't know plate current would be so close at such different plate voltages.

Thanks Sy

[kstagger]

I once built a triode-connected C3m linestage. The various brands of tubes I used were all really microphonic - reminding me off a globe 71A linestage I once built. The bounce of my Goldpoint volume control could be heard. Just something to keep in mind.

The filaments of the C3m are also very fragile. Never remove them from the sockets until the tube has been given a chance to cool. While troubleshooting my own preamp, I would pop 'em out and then when I placed them back in, suddenly I would lose a channel. This would lead me on a wild goose chase, thinking something went wrong with my circuit. Turns out the tube stopped conducting because the filament no longer lit up. Not a nice way to blow $25.