Hi,
First I want to make this clear, I can still recommend Traceless the 34465a from Keysight it is not a bad DMM!
The things I show below like this concern small deviations at the PPM level when using the Autocal function.
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So I paid the higher price, but the function doesn't work well, and I find that a bit sad.
I can still take accurate measurements as needed as I also have an Agilent 3458a standing by. but for good stability this DMM will need to be on for at least 12 hours,
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Here you can see the drift on my 34465a after using the autocal function.
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It may well be that the few PPM I have experienced is the "base" drift and if the ambient temperature is e.g. 25 degrees higher in a 19-Inch rack that this base drift I am measuring will cancel out against e.g. 15PPM drift that the Autocal function corrects.
I have no way to check this, I do not own a climate box to do good measurements in this regard.
I hoop this helps and if there are question, i like to hear them.
Kind regards,
Bram
Hello Bram,
I also have the 3458A, the 34401A and bought the 34465A in 2015 as an improved version to the latter.
I already identified several bugs around the ACAL and calibration functions, which went into two improved FW versions.
I also can confirm your observation, that meanwhile after an ACAL a 10Vdc measurement drifts about -1ppm before stabilizing.. this did not happen when the instrument was new. But I find that you have totally exaggerated expectations on your 34465A, and you know that yourself, I assume.
This instrument is neither intended, nor specified to make precision measurement below 13ppm stability (24h spec), in contrast to the 3458A.
We both know, that it performs better than specified. E.g. my unit is still inside 1y spec. in most of the modes, although I experimented and modified a lot on my instrument.
The ACAL function does of course not work like the one in the 3458A, that was also never promoted that way.
It only corrects for T.C. effects, and that really works very well, of course inside its specification limits.
I did such temperature tests several times, easy in winter time, i.e. let it cool outside, power on inside directly, and attach a 10V reference. Initial reading will be far off, still in spec though, by including T.C. of course, but after ACAL, it will display within 5ppm or so, I don't remember exactly. Repeat that ACAL during warm up, it'll still always be below spec. limits. That also works at elevated room temperatures, like in my bureau, instead in my basement lab which has R.T. = 22 +/-1°C over the year. I also can't confirm that the 34465A needs 12hours for stabilization, it's warmed up after 2h.
For the other DMMs I have no experience at all, but I suggest to make fair comparisons based on the specifications only: Do they really perform better than the 344465A for such parameters?
In this context, the relevant features why I bought the 34465A are: Offset Compensation for Ohm modes, long term data acquisition and digitizing modes, low DCI ranges (pA resolution), temperature measurement, and other useful features compared to the 344401A. So I also recommend to buy the 34465A, but get the MEM option for free, because that is needed for proper use of the built in DIG function.
Frank