Can someone ID this =C= tube for me?

[KissTone]

Sorry, I don't have a picture, but it's a big rectifier tube, coke-bottle shaped, with a 54 in a diamond printed on the glass. The only other thing I can see printed on it is 5"mu"3 ("mu" = the Greek letter). Thanks to anyone in the know!

[vibroverbus]

=C= is a Svetlana

The character is cyrillic...
Lots of info in the Interweb about translating russian tube designators..
Probably a 5 volt heater rectofrier, roughly equivalent to a 5Z4.

http://www.ominous-valve.com/russtube.html
http://en.wikipedia.org/wiki/Russian_tube_designations
http://www.valveheart.com/theory/rus_tube.html

[KissTone]

Thanks---that valveheart site seemed the best.