Electron tube 6P1P (6П1П) from manufacturer SVETLANA, St. Petersburg (RU). A quality russian output tetrode with minimum service life of 3000 operating hours (under optimal conditions according to the datasheet). Chinese version of this tube is marked 6P1. 6P1P does not have any direct replacement. It is very similar to the EL90/6AQ5, but it has a different pinout. Year of production: 1960. New old stock and tested.