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Fluke 233 cut off under 20mA
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J-R:
The DMM development process definitely leads to some odd results, such as the 233 missing the mA/uA function.  Another one is why the yellow select button is on the body and not the detachable screen portion.

I suspect things start with a marketing drone inventing a product design based on some competitor, imaginary use case or random customer requests.  Then the engineers have to make it.

Another major oddity is how few clamp meters have a mV range.  None of Brymen's do, for example.  The Uni-T UT210D has only DCmV.  The UEi DL489 does have it for both AC and DC, and is the only clamp meter I have with such a feature.  Someone probably thought having a major missing feature like that would require everyone to have both a clamp meter and a regular DMM, boosting sales.
bdunham7:

--- Quote from: J-R on April 24, 2023, 12:28:05 am ---https://web.archive.org/web/20121104004609/http://www.gellerlabs.com/34401A%20AC%20zero.htm

--- End quote ---

I'm not convinced that the 34401A is actually one of the meters that uses a simple "display zero if reading is below x.xxxmVAC" in software because it doesn't quite behave like that.  Perhaps they selected all the AD637 chips for negative residuals or perhaps the circuit can be tweaked to acheive this reliably?  Or there is something I don't see in the schematics that simply tapers off inputs below some threshold?  It isn't a clean zero, there's always a few counts hanging about.

Edit:  I should mention that my 34401A sample size is one and my firmware version is 10-05-02.
alm:

--- Quote from: bdunham7 on April 24, 2023, 12:32:20 am ---I agree--the datasheet is both technically wrong and badly misleading in this regard.

--- End quote ---
I agree it's misleading, but the form 0.1 mA - 6 A is commonly used to indicate 6 A with 0.1 mA resolution. It's not like the unit will read 0.1 mA DC with any kind of accuracy or stability. Although in the case where it won't even display 0.1 mA AC it is obviously misleading. Since the OP is in the EU, they could complain to the seller (not Fluke) that they received a non-conforming product that does not meet reasonable expectations based on the data sheet.


--- Quote from: J-R on April 24, 2023, 01:03:44 am ---The DMM development process definitely leads to some odd results, such as the 233 missing the mA/uA function. 
[...]
Another major oddity is how few clamp meters have a mV range.  None of Brymen's do, for example.

--- End quote ---
That's just them targeting specific markets. Clamp meters are usually aimed at (industrial) electricians who don't have much use for mV. Having more functions would clog up the function dial and make it more expensive. Fluke used to have a 112 DMM aimed at HVAC technicians which had 6A/10A and an uA range. The uA range was aimed at measuring flame sensors. It had no mA ranges because this is not necessary for troubleshooting HVAC systems. If you need the missing functions/ranges, then don't buy that meter.
J-R:
The F233 is only capable of 1mA resolution, so 0.1mA is completely wrong in all respects.

I do not agree with the argument that clamp meters are missing mV because they are targeted for industrial electricians.  It's very hard to find this feature missing on an industrial handheld DMM.  Also, many DMMs combine the mV range into the V switch position.  The 87V does this for mV AC, the UT210D does this for mV DC, the U1233A does this for both AC & DC.
Fungus:

--- Quote from: J-R on April 25, 2023, 07:55:28 am ---I do not agree with the argument that clamp meters are missing mV because they are targeted for industrial electricians.  It's very hard to find this feature missing on an industrial handheld DMM.  Also, many DMMs combine the mV range into the V switch position.  The 87V does this for mV AC, the UT210D does this for mV DC, the U1233A does this for both AC & DC.

--- End quote ---

That's just Fluke protecting their 87V cash-cow. All their other meters are designed around not being a substitute for the 87V, eg. missing mV, missing uA, or whatever.

They're a business and out to make as much money as possible, let's not pretend they're anything else. They're certainly not competitive or innovative any more.
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