Products > Test Equipment
EEVBlog 121GW Discussion thread
dcac:
--- Quote from: J-R on February 10, 2021, 09:06:49 am ---Is there a discussion about the fact the 121GW is 99,999 count when in calibration mode?
--- End quote ---
Not that I can recall - other than it’s been mentioned Agilent U1282 which is a 60,000 count meter also uses the HY3131.
And then there's this: https://reference.digilentinc.com/reference/add-ons/dmm-shield/reference-manual which is also based on HY3131 and claims to be a 5 1/2 digit meter.
But HY3131 is only rated for 50,000 count at a specified sample rate, accuracy and linearity in the datasheet. But it is in fact a 24bit ADC so theoretically you could get 2^23 or 8388608 count - in a perfect world that is.
But I noticed that too with 121gw in calibration mode that many modes/ranges acts as a 99,999 count meter. But I think the 5M and 50M ohms ranges only reaches 67,000 or something like that.
J-R:
Ran a bunch of tests and was surprised that specifically all the DCV & DCmV ranges were quite accurate all the way up, for example 9.87654V on the calibrated supply was 9.8764V on the 121GW. Past about 2 9's on the display and things were a bit off, however.
mA and A gained the extra headroom but the accuracy wasn't quite worth it. Capacitance and resistance were spotty as well. Some useful information could possibly be found under certain conditions.
Pushed 990V through it for about a minute with no issues. It still beeped constantly despite happily displaying the correct voltage...
skysurf76:
Anyone have any idea how often Dave gets shipments of 121GWs? I'm wanting to pick up another but they are currently out of stock.
Brumby:
From what Dave has said recently, I don't think even he can answer that at the moment. It appears there are supply issues with some of the components - which would make it difficult for even the manufacturer to give a date.
skysurf76:
I figured that might be the case. Thanks Brumby.
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