Electronics > Metrology

Hioki DM7276-01 Precision DC Voltmeter (9 PPM)

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Alex Nikitin:

--- Quote from: wanghar on July 08, 2024, 10:01:56 am --- Is this Hioki's style that not allowing users  to do calibration  by themselves?  :o

--- End quote ---

Not just that, so far I can not get any calibration information on my new meter from them or from the seller (Farnell UK) :palm: . And I am not even sure where I could send the meter for calibration! (OK, calibration is simple and any decent calibration lab should be able to do it, however if the meter needs adjusting, it might be a problem) .

Also the 3-year manufacturer's warranty on these meters is not transferrable from the original owner, so if you sell your meter or try to buy one second hand, there is no warranty even for a relatively new meter. Don't get me wrong, I like my DM7275 , use it all the time and won't swap it for almost any other meter, including the HP3458A, however the customer service from Hioki Japan is essentially non-existent and even from the distributor I can not get much sense so far in regard of calibration data.

Cheers

Alex

HighVoltage:
I had tried a few times to the password from Hioki Japan but so far I had no luck.

Alex Nikitin:
I've measured the DCV output of my HP3245A from -10V to +10V in 1V steps with the HIOKI DM7275. The measurements were made at 10V range, SLOW speed, 10 averages per point, with the input cables polarity reversed for the second run. Vset = voltage output setting on HP3245A, V = measured voltage with the correct polarity, Vr = measured voltage with the reversed polarity. V+Vr is the difference between measuring the same output voltage in two polarities. There is a small meter/cables offset about -2.5uV which I did not null. Vertical scale is 0.5ppm = 5uV per division.

Cheers

Alex

Alex Nikitin:
And here is a 24h measurement run of 10V output from HP3245A, there is a visible tempco of about -0.5ppm/C for the two units and connecting wires. The room temperature (orange line) varied from 24.5C to 25.7C. Right now I'm running the same measurement for 1V output.

Cheers

Alex

aronake:
Has anybody managed to figure out how to adjust a DM7275/DM7276 except for using the mentioned scaling hack?

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