> I have been experimenting with some NTC thermistors to use
in a filament
> transformer 120vac primary to limit the secondary (tube
filament) current flow.
> The unit showing the most promise, model CL90, is rated at
120 ohms cold,
> dropping to about 1.2 ohms hot.
Is a resistor not good enough for you? If the transformer is
not huge in
comparison to that needed, then it will limit the inrush
current. A
simple resistor will do a bit more.
Amen, David.
I always use a power resistor of the correct wattage for the
job, with a slider contact on it. This not only allows me to
set the exact operating voltage at the tube pins, but it is
also an inrush current preventor. I learned this from Henry
Radio; used on many of their amps/generators.
(((73)))
Phil, K5PC
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