Vacuum tubes produced in the former Soviet Union and in present-day Russia carry their own unique designations.
In the 1950s a 5-element system (GOST 5461-59, later 13393-76) was adopted in the (then) Soviet Union for designating receiver vacuum tubes.
It consists of a dash ("-") followed by a single character or a combination of characters and denotes special characteristics (if any) of the tube: For instance, -YeV (Russian: -ЕВ) added after 6N2P (i.e. 6Н2П-ЕВ) signifies that this variant of the 6N2P has extended service life and low noise and microphonics.
For example, a Soviet-produced copy of the 6L6 was originally manufactured in the 1940s under its American designation (in Latin lettering), or sometimes a Cyrillic transcription of it, 6Л6.
[5][1] A number before a cathode-ray tube designation gives the screen diagonal or diameter in centimeters (rounded to the nearest whole number) The 1st element: Function The next elements are: Popular transmitter tubes include the ГУ-29, ГУ-50, ГМ-70 and Г-807 (the Russian 807 analogue).