Products > Test Equipment
Brymen 869s DC offset issue when reading ACmV
joeqsmith:
--- Quote from: mqsaharan on January 21, 2022, 05:19:25 am ---And for 61E drifting problem, watch the following video from Joe.
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--- Quote from: AnalogEngineer on January 23, 2022, 03:38:13 am ---As to the 61E comment. My issue with Uni-T is not temperature drift. It's time drift. Take a Ut-61E and wait 6 months and it will be way out of calibration, unacceptably so. That doesn't help me trust Uni-T. Even the cheap Anegs and Harbor Freight meters hold calibration. Not so much Uni-T.
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I continue to monitor the long term drift after making those modifications. It appears it has been almost a year since the I last checked.
Martin72:
--- Quote from: bdunham7 on January 23, 2022, 04:08:11 am ---The 289 can be fairly criticized--it is expensive, big, cumbersome to use according to some and it eats batteries like popcorn.
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:-DD
So damn true....
2N3055:
--- Quote from: Fungus on January 23, 2022, 08:05:07 am ---
--- Quote from: _Wim_ on January 23, 2022, 07:14:42 am ---I wonder if this could be related to the fact that the OP does not achieve the expected accuracy? Many he could try manual ranging and see if the accuracy improves on a high range for his test signal.
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A BM869S can easily read a 100mV AC signal with 7.5V DC offset in the normal AC+DC range.
I think the problem is that he wants it in dBm
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And it can easily do the dBm too, and at the levels OP asked for.
It won't be accurate down to 0.1 dBm, mind you... It will be inside 0.3-0.4 dBm of reading.
But if you ask me, it this is critical testing, for pretty much the price of F289 + a bit more you can get DMM6500 and do it right...
Precision testing is not a handheld job. Also, you might need some kind of record or printout of "Passed" label....
bdunham7:
--- Quote from: 2N3055 on January 23, 2022, 10:10:17 pm ---And it can easily do the dBm too, and at the levels OP asked for.
It won't be accurate down to 0.1 dBm, mind you... It will be inside 0.3-0.4 dBm of reading.
But if you ask me, it this is critical testing, for pretty much the price of F289 + a bit more you can get DMM6500 and do it right...
Precision testing is not a handheld job. Also, you might need some kind of record or printout of "Passed" label....
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F289 will do that measurement (100mVAC @500Hz, -17.78dBm) 10X more accurately (+/- 0.02dBm) if that's what he needs. The errors get down to the point where the typical 1M input impedance of a bench meter may affect the results more than the lesser precision of the F289, if the source is actually 600 ohms.
joeqsmith:
--- Quote from: 2N3055 on January 23, 2022, 10:10:17 pm ---.... But if you ask me, it this is critical testing, ....
...Precision testing is not a handheld job. ...
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I would be concerned if I worked for a company who was having problems buying a few new handheld meters let alone trying to save the cost of their production testing. :scared:
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