Emco makes a potted module that ouputs 0 to 10kv at .2ma with .7 to 15vdc
input. They are available on Ebay for about $40 by searching for "10kv".
I use one of these and my trusty old Heathkit VOM on the 5kv range as a
series current limiting resistor and leakage detector. The vom is 50 ua and
100m
resistance in this range which will limit current flow to 100ua maximum at
10kv.
In practice the meter would be pegged out in this case so one would adjust
the input voltage low enough to prevent this.
The input vs output voltage curve is virtually a straight line so it is easy
to to estimate the output voltage by monitoring the input 0 to 15v. You have
to subtract the voltage drop of the vom of course to reach total voltage across
the device being tested. In practice, adjusting the input voltage upwards
until the vom just begins to move off zero works well as you can neglect the
voltage drop related to the vom.
I didn't have an adjustable 15vdc power supply so used a 13.8vdc unit, 1k pot
and TIP120 as an emitter follower to provide 0 to 13vdc for the module. In
this case the maximum output voltage is about 8600vdc which has been plenty
enough to test tubes, vacuum devices and bypass caps for leakage. I found out
right away that almost everything in my junkbox was much worse for leakage than
I
had ever imagined.
For lazy builders, like me, it doesn't get much easier than this!
73, Gerald/K5GW
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