08-11-2012, 09:31 PM
(08-11-2012, 07:17 PM)Skywave Wrote: To the best of my knowledge, it was only Mullard who produced 'magic eyes' on the side-contact base. The possibilities are TV4, EM1, EM3 and EM4. Identification can be determined by inspection of the valve socket wiring and a heater voltage measurement. The TV4 is the only one with a 4-v. heater; the others are 6.3-v. The EM1 is effectively a 6.3-v. version of the TV4. The EM3 is a more sensitive version of the EM1. The EM4 is a dual sensitivity version of the EM3.
Al.
Hi Al, there was also the EFM1 also CT base, it was the pentode version, doesn't look like thats the one in Andrews unit though.
lawrence.
