Admiral 14R12 Restoration

[Electronic M]

Another thing to consider is that if it is a flat faced CRT it could have poor edge focus by design...Early rectangular and large screen tubes had flat faces which was quickly moved away from by makers...You see as the beam is swept the physical distance the electrons travel increases as you move away from center. Curved screens were designed to keep electron travel fairy constant at all points of the screen during scanning....Some makers tried to apply sweep derived AC to the focus on flat faced tubes to reduce that effect, but on sets that lacked that you kinda have to live with what you have (which usually involved setting focus for a compromise between edges and center).