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Amprobe AM-220 out of calibration in less than 18 months.

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I have had this AM-220 for a year and a half now and when compared to my other 2 multimeters it seems to be out of spec. I am measuring a -0.6% error (with 2 counts added just in case, could be worse) on the lowest DC volt range. The accuracy is reported to be 0.5%. This worsens on higher ranges, up to 0.8% on the 4V range!. The other 2 multimeters measure exactly the same voltage on most conditions. These are an Extech EX330 (0.5% accuraty ±2 counts) and a Keithley 191 (0.007% ±3 counts 1 year accuracy).  As you can see, the odds are against the Amprobe being in-spec.

I am starting to dislike Amprobe for this. They are supposed to be more reputable, but this meter drifted out of spec very quickly. It also has some issues with the range switch, which has become a bit erratic. I suspect it has to do with the contacts having some issues. This multimeter hasn't been dropped. It hasn't even been out of the lab (the Extech one has). I am looking to adjust it back to spec, but I want to hear your opinion on this.


I have a Uni-T that is rated at 0.025% at lowest voltage range, and 0.05%, at +5 counts. It arrived at close to 0.4% accuracy. Even at the number of counts out it could be at the test voltages, it was still way out of spec. Now I am griped like crazy and still do about this, but it really is only a sample of one and I cannot be so emphatic about the lack of accuracy of all Uni-T meters based on that one meter. Sure I should have received one that was within spec. Can I say that from one example from a manufacturer that all of their meters are not to be trusted? No. Should I base my opinion on Uni-T solely on that one experience? No. I have other  Uni-T meters and based on my experience with them I would be able to say that their quality and accuracy are variable.

The same applies to your meter. It can not be the basis for a fundamental conclusion that all Amprobes are bad. You have a sample of one. One also needs to ask whether the other meters are at the limit on one end and the Amprobe is at the other when you are cross checking. You are probably right and the Amprobe is out. The Amprobe might have been just in spec when you got it and is moving outside of spec now.

Don't let one bad example makeup your mind on all.

I have had my AM-220 for about 2 years now. I see no problems with mine...yet.

Lots of components to go bad, get knocked out of adjustment,  or get zapped.   You can't tell from just one experience.  Maybe others here can let us know if they have had better luck or similar problems.  There is usually a lemon in every batch though no matter what brand.

30+ years is pretty good though.  Here's my Flukes.

I have two Fluke 8000 series bench meters that are dead on and never been touched also.

I've been thinking about buying a AM-270 to try out for a while and then giving it to one of the kids who needs a good meter for automotive work.

I don't know why you are so surprised. A drift on any new multimeter is quite normal after a period of one year, at least until all components have aged and settled. Most companies recommend a calibration every year. If the meter has some adjustment pots, it would be a painless exercise to bring it back in line with your other multimeters.
Keep in mind that a 'new' multimeter may not be new at all, the date of manufacture is the guideline here, not the sale date.


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