(29-08-2011, 08:01 AM)Yorkie Wrote: Yes, if it's the post-war T16/T17 AC only version they had 6.3V parallel heaters powered from an auto transformer, using an indirectly heated cathode on the rectifier valve, powered from the same 6.3V supply, rather than from a separate winding. An auto transformer is far superior to a mains dropper as it doesn't dissipate the heat that a mains dropper does, which is kinder to the cabinet and to other components, though as you say, the same precauions must be taken as an auto transformer doesn't isolate the chassis from the mains.
David, According to my Trader service sheet the Transformer is a conventional double wound isolation type transformer and on test the windings do appear to be seperate, but both primary and secondary windings are connected to earth which would negate any isolation, so just as dangerous just a little cooler. The Bakelite case also doesn't have the Asbestos heat shield built into the top, which was probably more dangerous to life than anything else ...........
Mike
