(!!!) (Single) KT66 Osram UK black base used 1950's (57ma) (Gm=60%)
(!!!) (Single) KT66 Osram UK brown base used 1950's (62ma) (Gm=65%)
(Display Tube) KT66 GEC 1960's (WEAK TUBE: LOW Ma and LOW GM) - for display purposes only
(Display Tube) KT66 GEC 1971 purple gas - for display purposes only
KT66 GEC UK brown base used/70% 1966 (64ma)
