I am in the throes of building a grid-driven amplifier using a tube
with a thoriated-tungsten filament that has a rather unusual filament
voltage, and my filament transformer has no center tap.
I know about the "trick" of using a smallish center-tapped
transformer to provide the cathode return, where the transformer
needs to be rated for the DC cathode/anode current. I am prepared to
do this, but...
I have seen designs for using such directly-heated cathode tubes
which simply attach the cathode common return to one of the filament
connections. (The filament connections have multiple RF bypass
capacitors between them, and to ground.)
What are the arguments for and against each of these approaches to
providing the "cathode return"?
George T. Daughters, K6GT
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