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FOr those who commented on my previous post - thank you - here is an update form Keysight themselves:"The understanding of the 5% of range and 100% of range is correct. That the guaranteed range for measurement under the 1000.0mV range would be actually 50mV to 1000.0mV. Sadly to say there is no method for the U1241B to be able to measure such a low voltage."
So, the U1241B multimeter cannot do what is claimed on P.17 of their brochure: ACV range of 0.1mV to 1000V.
Otherwise, it looks like a nice device, I think, but I really don't know if the other ranges and accuracy quoted can be trusted. I have requested that Keysight provide accurate details of all measurement ranges - I will make decision when this has been received.
Edit: actually, their datasheets can probably be trusted.
Regards,
91.
"Confusion of goals and perfection of means seems to characterise our age." Albert Einstein
Edits: 09/02/15 09/03/15Follow Ups:
Provided the input to the meter is greater than 50 millivolt it will measure it within a tenth of a millivolt. Kudos to them for making this clear.
Go look at the specs for their meters that cost WAY more money. There are the same limitations. Even something like their 3458A states accuracy is only valid for inputs greater than 10% of the scale. Keep in mind this is a $10,000 meter. Do you really think Fluke knows something about how to build meters that HP/Agilent doesn't?
Yes, Fluke knows how to build a flexible meter. AP/Agilent wants to sell you a different tool for each job.
The *accurate* measurement range has been confirmed and that is well understood now. What I am unclear on is low measurement bound, irrespective of accuracy.
Hx:
My experience suggested that the mm seemed unable to measure the low mV of DHT filament hum. I sought clarification from Keysight regarding the low measurement bound. They now appear to be stating that the mm cannot measure mV as low as I need. By contrast, the Keysight mm brochure clearly states the mm can measure from 0.1 mV. A high degree of accuracy in the low mV range is not expected, but given their brochure, some type of measurement is to be expected.
Late development: I have just received confirmation that the their brochure is incorrect and will be changed.
This clears things up.
Regards,
91.
"Confusion of goals and perfection of means seems to characterise our age." Albert Einstein
It can resolve 0.1 mV, but accuracy is not specified below 5% of full range. Seems reasonable to me. If I'm measuring in the mV range, I wouldn't be using a 1V scale - I have an audio voltmeter that goes down to 1 mV full scale. A 'scope would be questionable at these levels due to common mode effects though it's usually the best choice - the wave shape can be helpful in identifying the source of hum.
"A high degree of accuracy in the low mV range is not expected, but given their brochure, some type of measurement is to be expected."
It's still not clear what's actually meant in their reply to you:
"...the guaranteed range for measurement under the 1000.0mV range would be actually 50mV to 1000.0mV. Sadly to say there is no method for the U1241B to be able to measure such a low voltage."
The meaning of the word "measure" in this context isn't at all evident. They didn't say that it can't detect such low levels, or that it will read zero for signals below a 50mV threshold. Telling you that the brochure will be revised doesn't help either; they didn't provide the revision itself. All things considered, I don't think their reply has clarified the point you asked about.
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