[volt-nuts] How can I make a 2000 V DC meter with an input resistance of at least 100 T ohms?

[Dr. David Kirkby]

On 24 March 2018 at 17:34, Jeremy Nichols <jn6wfo at gmail.com> wrote:

> I made a high-value resistor using motor oil and a couple of stainless
> bolts. It worked for what I was doing (testing an HP-425A
> Microvolt-Ammeter) but calculated as only 8,500 Megohms.
>
> Jeremy
>

I had some discussions some time ago about using oil as a dielectric in a
capacitor with someone at NPL. He said the loss of both cyclohexane and
Polydimethylsiloxane (PDMS = silicon oil) is very low. He said the only way
I would measure the loss of them was a resonate method, and detecting small
changes in Q. My thoughts on putting them as the dielectric in a capacitor
and measuring on an LCR meter would not work, nor would my transmission
line. I had already satisfied myself that using a coaxial probe and VNA
would not work.

As he said, cyclohexane is nasty stuff, but PDMS is much more
environmentally friendly.



Dave