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| Brymen 869s DC offset issue when reading ACmV |
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| AnalogEngineer:
Howdy, I recently got a Brymen 869s in the hopes we could find a lower cost alternative for the Fluke 289 / 189 we use on the shop floor. We need at least 20,000 counts and dBV or dBm reading so the choices are slim since few lower cost non Fluke meters include dB readings. There appears to be a show stopper bug and I wonder if anyone can confirm or knows a work around solution. I suspect the bug is the same causing this issue, but since that is an old thread I decided to start a new one. https://www.eevblog.com/forum/testgear/brymen-multimeters-fault/ What it appears is that when using the AC mV reading the meter is not AC coupled. So if there is a DC offset that is more than the maximum DCmV scale the AC mV reading will not work and you get nonsense readings. This also seems to affect frequency and AC / DC dual readings as well. In my case I am reading a 100mV signal riding on top of a 7.5VDC offset. My Fluke 289 handles this perfectly for all measurements as does my ancient Keithly and Tektronix models. The Brymen 869 cannot and I have to go to the AC Volt reading (with less accuracy due to small voltage). If I add a >0.22uF capacitor in series then it works but takes a 5-10 seconds to settle down to an accurate reading (due I assume to the meters input impedance). Smaller capacitors induce error in the value and larger increase settling time. Any ideas? This seems like such a huge fail on the meters part basically making it unusable to me in our application. Anyone want to recommend a sub $300 meter with >=19,999 counts and dBV or dBm reading capability? |
| Fungus:
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| mqsaharan:
--- Quote from: AnalogEngineer on January 19, 2022, 04:30:44 pm ---Anyone want to recommend a sub $300 meter with >=19,999 counts and dBV or dBm reading capability? --- End quote --- I am not sure about the price in your country but may I suggest UT181A. It is another blatant attempt to copy Fluke 287 externally and functionally like some others. Even though its manual does not state measurements in dBv or dBm, its VAC menu does include both. Please check out the following link for Joe Smith's video at 17:50 minutes mark It has AC coupling cap in it. And I can only hope it will also have AC coupling on mVAC range because usually the meters that have an independent mVAC range are AC coupled in that range unlike the ones that share one dial position for both DC and AC mV function. I hope some other member who owns one will confirm AC coupling as well as dBV and dBm capability on mVAC range for UT181. |
| Fungus:
--- Quote from: mqsaharan on January 20, 2022, 07:38:33 am ---I am not sure about the price in your country but may I suggest UT181A. It is another blatant attempt to copy Fluke 287 externally and functionally like some others. Even though its manual does not state measurements in dBv or dBm, its VAC menu does include both. Please check out the following link for Joe Smith's video at 17:50 minutes mark --- End quote --- It's a good meter but the the fancy screen means the battery doesn't last very long and you can't use it while it's charging becasue it charges through the input jacks. This can make it very inconvenient to use. (plus it's a LIPO battery so it won't even hold a charge a few years from now) joe says the battery lasts about 40 hours in a new meter: https://www.eevblog.com/forum/testgear/uni-t-ut181a-pictures/msg3327088/#msg3327088 |
| AnalogEngineer:
--- Quote from: Fungus on January 20, 2022, 12:42:44 pm --- --- Quote from: mqsaharan on January 20, 2022, 07:38:33 am ---I am not sure about the price in your country but may I suggest UT181A. --- End quote --- Thank you. I had not considered that before. I wonder how stable it is. I have two Uni-T ut61e meters now and they both drift like crazy and don't stay in calibration more than a few months. This is a known complaint with Uni-T. Even my cheap Anengs don't do this. I wonder if this meter suffers the same issue. I also wonder if the UT61e+ has fixed this. Otherwise it seems to be a great meter. The 61E actually meets all my needs except the dB reading so worth considering. Someone else mentioned to me the Vici VICHY VC8145 which seems possible. Alas all this trying other brands is making me a bigger Fluke fanboy. They are all so close, but I keep seeing small details that does make the fluke much nicer. I just can't afford them for every tech at the shop. Sigh. --- End quote --- |
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