Electron tube 6P1P-EV (6П1П-ЕВ) from manufacturer SVETLANA, St. Petersburg (RU). A quality long life russian output tetrode with improved mechanical strength. Not less than 5000 operating hours under optimal conditions. 6P1P-EV does not have any direct replacement. It is very similar to the EL90/6AQ5, but it has a different pinout. Tubes were produced in the 70's and 80's. New old stock.