Osram Catkin tetrode valve, type MS4B, B5 base, with screening can and top terminal, (RMW/G63 - McVitie Weston number), by Osram, 1933.
Osram Catkin tetrode valve, type MS4B, B5 base, with screening can and top terminal, (RMW/G63 - McVitie Weston number), by Osram, 1933.