Electron tube SG13P (СГ13П) is a voltage regulator 149±6V. Operating current range: 5 to 30mA. SG13P may be a better option (comparing to the SG1P) when replacing similar tube types like 11TA31, STV150/30, STR150/30, 0A2, 150C2. Pinout is identical, parameters are +/- the same and SG13P has also thinner (typical heptal type) glass envelope. Comparing to the 11TA31 is the SG13P significantly lower, but that is not such a problem. The only disadvantage of this tube is its lifespan: not less than 1000 operating hours. New old stock tubes, directly from the factory packing. Years of production: 1974, 1979 and 1982.