Products > Test Equipment
Brymen 869s DC offset issue when reading ACmV
Caliaxy:
--- Quote from: Neutrion on January 24, 2022, 07:24:50 pm ---The 87V has no mV scale so if we are talking about the V AC scale the Brymens read also correct on the v AC scale.
--- End quote ---
That's actually the interesting thing we noticed while having this discussion in the BM789 thread.
Fluke 87v has a DC mV position on the dial (with a single 600mV range). There is no AC mV position on the rotary dial per se, but there is a 600mV AC range on the AC V position of the rotary dial. I suspect they did this precisely to avoid the issue under discussion here without adding an extra position on the dial (the alternative would have been having a common AC/DC mV position on the rotary dial and switch between AC and DC with a soft touch button).
bdunham7:
--- Quote from: Neutrion on January 24, 2022, 07:24:50 pm ---The 87V has no mV scale so if we are talking about the V AC scale the Brymens read also correct on the v AC scale.
--- End quote ---
It actually does, in fact IIRC in Hi-res mode it has a 200.00mVAC range, so 10uV resolution.
Caliaxy:
A quick fix for the OP (other than a capacitor) would be to use a lab power supply to subtract the offset. Set the output of the power supply to the offset voltage (7.5V), connect (V-) to the GND of the DUT and use BM689S to measure the AC voltage between the measuring point and (V+) on the power supply (as opposed to GND or V-).
Fungus:
--- Quote from: bdunham7 on January 24, 2022, 07:50:06 pm ---
--- Quote from: Neutrion on January 24, 2022, 07:24:50 pm ---The 87V has no mV scale so if we are talking about the V AC scale the Brymens read also correct on the v AC scale.
--- End quote ---
It actually does, in fact IIRC in Hi-res mode it has a 200.00mVAC range, so 10uV resolution.
--- End quote ---
So the OP can simply use AC range (or AC+DC range) with no problems?
Neutrion:
--- Quote from: bdunham7 on January 24, 2022, 07:50:06 pm ---
--- Quote from: Neutrion on January 24, 2022, 07:24:50 pm ---The 87V has no mV scale so if we are talking about the V AC scale the Brymens read also correct on the v AC scale.
--- End quote ---
It actually does, in fact IIRC in Hi-res mode it has a 200.00mVAC range, so 10uV resolution.
--- End quote ---
Maybe this one goes to the 87V but it would be still interesting to compare the 87Vs 200,00mVAC range(0,7%+1d) with the 789s 6,0000VAC range 0,5%+30d in an actual test.
Did by the way anyone tested this scale of the 87V with a DC bias, and for overrange indication?
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