Mullard detector or AF triode valve, type 904V, B5 base, short gauze anode, (RMW/F50A - McVitie Weston number), by Mullard Limited, 1931.
Mullard detector or AF triode valve, type 904V, B5 base, short gauze anode, (RMW/F50A - McVitie Weston number), by Mullard Limited, 1931.