[R-390] Re 26Z5 replacement

[Bill Hawkins]

pete williams said,

" The power xfmr has a 12 V tap
unused at terminal #9. Rewiring to put the  fils in series  may not
cause   a load problem especially if  ovens  not  used. The  seriesed
fil  current would be 0.9  amp .
Any prohibitions ? "

Well, I've done no research, but rectifiers have heater-
cathode voltage concerns. These go away if you connect
one side of the heater to the cathode, but then you have
to worry about the transformer insulation for the heater
winding.

You could wire the tube heaters up for the glow, and conceal
diodes under the tubes. 'Course, nobody's going to see the
glow in the normal operating position.

No worries, mate, you'll think of something ...

Regards,
Bill Hawkins