> The 4CX1000A needs 6.0 V at 9 A, but of course when cold it will be a very
> low
> resistance. I thought of using a 7.5 V 13.5 A switch-mode supply, with a 0.17
> Ohm series resistor to drop 1.5 V. But I'm concerned the heater will never
> get
> hot, as the cold resistance of the tube will draw too much current, causing
> the
> SMPS to shut down.
Hunt around for a PSU that does current limit rather than shut
down. Some have the option to switch between the two.
Alternatively, add an external current limit circuit that's
switched out once the heater voltage rises far enough.
Steve
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