Re: Calibration of 4285A Precision LCR meter 75 kHZ to 30 MHz. 0.1%
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Dr. David Kirkby from Kirkby Microwave Ltd
On Mon, 1 Oct 2018, 04:10 Don Bitters via Groups.Io, <donbitters= [email protected]> wrote: All, please note that where 5V is referenced in the ¡°strange readings¡± it is actually 5mV and the high allowed reading is 6.42mV.? This would not be out of range accuracy as this is probably the bottom of the 100mV range.? If the range accuracy is 1.5% (1.5mV) then this is the tolerance.? The actual reading is better than that.? The actual reading tolerance is described in a more complicated but more precise fashion.
See the manual for the exact description of the accuracy and the calculations that derive it.
Thank you for the explanation.?
The 4284A/4285A/4286A family of LCR meters is my favorite of all of the HP, Agilent, Keysight LCR meters.
I also have an old 4263A LCR meter I bought fairly cheaply. It has a rather annoying user interface.? The interface on the 4284A & 4285A is 100 dB better than the 4263A.
They always read more accurate than the spec. and were extremely repeatable.
Don Bitters
That's an interesting comment you make about thei accuracy if the 4284A & 4285A.? One of the other things I found odd on the 4285A cal certificate was the use of a 4284A (20 Hz to 1 MHz) LCR meter as equipment used for calibration. It is not obvious to me what measurement is taken with the 4284A.?
Also I note that the 4285A was calibrated in June 2012, but Agilent's own 4284A was not due for calibration until January 2014 - a period of more than 18 months.? That struck me as a bit odd given the calibration interval recommended for the 4284A LCR is only 6 months.?
I often wondered if the short (6 month) calibration interval of the 4284A was a reflection of the fact it drifted quite a bit.?
Although I have a 4284A which I had calibrated by Keysight about 2 years ago, I don't know if my 4284A was received in spec or not. Keysight kindly agreed to give me the software option 006 (4 m lead length) free. As such it was considered a new/refurbished instrument, with no "before data" available.?
I wonder why Keysight discontinued the 4285A. There is no obvious replacement for it. The highest frequently 4TP LCR meter Keysight now have is 2 MHz, but the 4285A covered up to 30 MHz.?
Dave.?
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