[ARC5] Use of a Variac

[Hubert Miller]

A current - metered variac is a rare and expensive animal and I'm not sure the resolution of the meters on those is even useful for small current draw.
Some VOMs have AC current scales which may be more useful.
If the equipment has a tube rectifier, one could remove it, bridge one side with a ss diode with a DC current meter in series. Assuming no other shorts
exist already in the equipment. 
I dislike lytic caps, especially HV ones, because those are the component most likely to fail. But there's not yet a really ready replacement. Poly caps
are wondrous but they tend to be large and expensive and limited in capacitor size. HV FET regulators are another possibility but not a trivial plug-in
replacement.

Tom, I worked the formula for 500 volts and 20 uF and got a limit of 0.1 mA.  Did I do it right? That seems a pretty rigorous standard.
-Hue