On Jun 12, 5:00 pm, "Ross, NS7F" wrote:
In a circuit with two 6.3V tubes, can I just series the filaments so
that I can use a 12-13.8V supply? Or are there subtleties that I'm
missing?
Thanks,
Ross NS7F

Depends on the tubes . If the two are same type ,you can series
them ,no problem.. If the two tubes draw different current,then you
can use a parallel resistor to equal the current in each tube...Old
radio amateurs handbook is a good source fr this inf... GL W4PQW