B9D base
The 9-pin B9D (Magnoval) tube base (IEC 67-I-36a) is a larger variant of the B9A (Noval) miniature 9-pin base developed for higher-powered European tubes such as the 8608/EL5070, 8233/E55L, PL509/PL519 TV sweep tubes, etc.
It has nine pins with 1.27 mm (0.046") diameter in a 17.45 mm (0.687") pin circle diameter arc.
The similar B9E (Novar) base used by comparable American tubes has the same pin circle geometry but the tube pins have a diameter of only 1.02 mm (0.038"). Inserting Magnoval tubes into Novar sockets by force will widen the latter's contacts, thereby damaging the socket.