[Test-Equipment] HV probe resistor selection

[David]

On Sat, 23 Feb 2013 02:10:56 -0800, DaveC <davec2468 at yahoo.com> wrote:

>Thanks for your comments.
>
>The 25 M resistor is 4 inches long. No room in the probe body for 3x.

The 25 megohm 3.8 watt resistors are just over 1 inch long.

>I'm leaning toward the 1 G resistor and selecting an appropriate R2 plus 10- turn pot to calibrate.

That will certainly work.

>But still open to suggestions.

If you are interested in accuracy, then the physically longer
resistors have a lower voltage coefficient of resistance.  You can
also get better accuracy by using multiple resistors in series which
lowers the effect of the voltage coefficient of resistance.