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FLUKE 87V High Z mode input Impedance value

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kg4arn:
I can't find any documentation on the input impedance value for the FLUKE 87V in the High Z mode (600mV) range.

In a previous thread:  https://www.eevblog.com/forum/chat/i-need-to-know-the-history-of-fluke-87-(-1998-2010-)/msg3907/#msg3907  it was said to be greater than 4000 Megaohms.

Is this the correct number?  I can measure the loading effect of the 10Meg input impedance but I am unable to measure the loading effect in the High Z mode, so I would believe the number quoted in the thread above.

alm:
As far as I know it's not specified by Fluke, but you can expect it to be >> 10 Mohm since it's just a FET input with some protection circuitry. Typical specs for similar meters would be something like >1 Gohm (note how they only give a minimum).

kg4arn:
Thanks alm

walter.aranda:
I confess that I have also had the same question, I even asked to ChatGPT IA, he told me that it is approx 10G Ohm (I attach the image, - it is in Spanish -) if it is possible using the "S" conductance reading function in nS (Available in Fluke 8X, 18X, 18X series), I have measured it, in Vac: 0.06nS = 16.67G Ohm, in Vdc: 89.36nS= 11.19M Ohm, in mVDC:43.55nS=22.96M Ohm. Which demonstrates consistency, since this function is generally useful for measuring very high voltages. Regards

tooki:
Remember that ChatGPT is not a search, and doesn’t know math, it’s just a statistical probability engine for what the next word is likely to be.

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