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On Sat, 9 Feb 2019, 16:02 Askild <megafluffy@... wrote:

At work we have the Agilent liquid test fixture, use together with a LCR meter to measure the permittivity of different oil's

Is there any chance you could take some detailed photographs and detailed dimensions? I have looked at the manual, but some more details would be nice.?

What of the BNCs connect to the guard ring?

Whilst I take your point one is making comparisons to air. There is some software from Keysight that supports that fixture, which might be tailored to it.?

I believe the electrodes are plated in platinum. I don't know if that's the best possible material to reduce the barrier layer problem. I know getting things gold plated is easy, but I am unsure about platinum.

I remember that my company didn't want to buy? more than one, due to price....

Yes, I can understand that!

Keysight also has one for solids as well

The price is way to high for these, but if you study the manuals, you will see that the construction isn't that advanced, so making one should not be a problem if you have access to some proper machining tools.

I managed to pick up one of those. I have often wondered if it could be used for liquids too, if one made a small tank to fit inside - like a small fish tank! Although it would make the maths tricky, if the properties of the tanks material were first measured, an analytical solution (excuse the pun) could be derived.?

As I write before I have reasonable results with using an air spaced capacitor, but the lack of a guard ring is going to reduce accuracy.?

And the dimensions isn't that critical as you compare the dialectic of what you want to measure against the dialectic of air.

But of course you will? need a instrument to connect to the test fixture.

I have a 4284A & 4285A, which were top of the line instruments in their day. Unfortunately the fixtures sell on the used market for more than the instruments do!

BR,

Askild

Dave