[Amps] Switching Power Supplies

[Steve Thompson]

Tom W8JI wrote:
>> I'm aiming for a floating supply as the current project is a tetrode
>> running with the screen at ground potential. I initially thought about a
>> dc supply where the switching frequency can be filtered to a minimal
>> level, but then I thought about using the ac (more or less square wave)
>> instead for simplicity. Capacitive coupling from the heater to the
>> cathode is quite high impedance, and the cathode is bypassed to ground
>> so I figure that the likelyhood of heater voltage getting transferred
>> onto cathode-control grid bias voltage is low.
> 
> 
> How will a switching supply handle a HV to ground fault if the tube arcs?
For what I have in mind, the heater supply will come from the secondary 
of a fully isolated transformer. 5kV insulation is easy to achieve and 
fault current shouldn't flow through the heater. I don't see any major 
difference from what happens with a regular mains transformer.

Steve