Thankyou for responding so soon . As I will have to find a suitable core for this , space might not be that much of a
problem . I have had a quick look in my workshop but I cannot find the original core , cant think why its not with
the bobbin . The original was potted in epoxy , it developed a short between the 2 x 1000 windings . Hard to track
down at first , then it behaved like a shorted turn after being on for a while and killed HV . I have the HV power
supply from a 545 -- dont know which version though but it does use the tube rectifiers , not solid state . Would
that be a suitable donor core ?
Yes! Any 500 series scope with plugins uses the same core +/- some
small variances that just don't matter.