Products > Test Equipment
Uni-T launches the UT117C multimeter
2N3055:
--- Quote from: ledtester on July 21, 2023, 06:59:41 am ---
--- Quote from: mwb1100 on July 21, 2023, 06:13:01 am ---
--- Quote from: sonpul on July 21, 2023, 05:15:47 am ---As they say, it's written on the fence.
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Sorry for going off topic, but I don't recognize that idiom. Is that a literal translation of an idiom from another language?
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I was curious too so I did some investigating. Given that the poster was from Ukraine I had Google translate "it's written on the fence" into Ukrainian: "На паркані написано".
Doing a web search for that phrase resulted in a lot of hits so it appeared that it was indeed a common expression / idiom. Translating some of those search results gave me a sense of what it meant but nothing definitive.
Finally I decided to ask Google Bard (i.e. Google's ChatGPT) for an explanation of the idiom and it responded with:
--- Quote ---Звичайно. Український ідіом "На паркані написано" означає, що щось дуже очевидне і не потребує пояснення. Він часто використовується, щоб виразити своє розчарування з кимось, хто не розуміє чогось, що, як вам здається, очевидно. Наприклад, якщо ви говорите з кимось про важливу подію, яка недавно відбулася, а вони просять вас пояснити, що сталося, ви можете сказати: "На паркані написано!" Це означає, що інформація вже доступна, і немає необхідності пояснювати її ще раз.
Ідіом "На паркані написано" також може використовуватися в більш жартівливому ключі. Наприклад, якщо ви бачите когось, хто робить щось дурне, ви можете сказати: "На паркані написано!" Це означає, що людина повинна була знати краще, і немає потреби пояснювати їй, що вона робить неправильно.
Ідіом "На паркані написано" - це корисний спосіб висловити своє розчарування або жарт з кимось, хто не розуміє чогось, що, як вам здається, очевидно.
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which translated is:
--- Quote ---Of course. The Ukrainian idiom "It's written on the fence" means that something is very obvious and needs no explanation. It is often used to express your frustration with someone who doesn't understand something you think is obvious. For example, if you're talking to someone about an important event that happened recently, and they ask you to explain what happened, you might say, "It's written on the fence!" This means that the information is already available and there is no need to explain it again.
The idiom "It's written on the fence" can also be used in a more humorous way. For example, if you see someone doing something stupid, you might say, "It's written on the fence!" This means that the person should have known better, and there is no need to explain to them what they are doing wrong.
The idiom "It's written on the fence" is a useful way to express your frustration or joke with someone who doesn't understand something you think is obvious.
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Perhaps native speakers can comment on the accuracy of this explanation.
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Meaning of that phrase in this context is "I don't care what they wrote I see meter doing much better than that and that is empirical proof instead of some irrelevant writing on the paper", as in "The proof of the pudding is in the eating"...
@sonpul insists that despite published 0.3% accuracy, meter is actually performing better and that because of that performance he considers it to be in 0.03-0.02% class.
Which is not the way it works. It might be (and usually is) that some product perform much better that spec. But fact that manufacturer specifies very low accuracy of 0.3% means that they deserve right to ship meters as bad as that. It could be that they devised very fast calibration fixture that can calibrate thousands of meters an hour but has wide variability or drifts during day... Even if you guarantee only 3 sigma variation in calibration there will be some perfectly calibrated meters in a population... And some as bad as spec allows.
Or they are just reserving right to put any quality components in there, or meter has large tempco or long term drift, so even after all this it will still perform inside specification.
Best way to guarantee that you will deliver up to spec is lowering expectations...
And you never know which one you're getting.
My Metrix and Brymens are almost an order of magnitude better than specification on some ranges and at the room temp.....And if the planets align.. But I would not trust them for more than specified for serious purposes.
That being said, 0.3% is good enough for most handheld use scenarios.
sonpul:
2N3055, Totally agree with you. It makes no sense to require an accuracy of 0.03%, but it can be obtained with a high probability. Now the price for this multimeter is about $70. And if the accuracy that we see in the reviews continues, then this is a very good choice.
alm:
--- Quote from: CosteC on July 21, 2023, 07:21:41 am ---It is stupid high resolution, 0.3% DCV meter. Well build, with couple of nice features like BT. Extra digit or two does not make it more accurate.
Short term accuracy and staiblity is far better than 0.3% - but same is true for any decent meter.
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That's true of course, but not everything is about accuracy. Say you are adjusting a trimmer for reading closest to zero. Or you want to see if a value is going up or down with ambient temperature. For that you need resolution, short term stability and linearity, but not accuracy. Quite a lot of measurements are like that. Matching resistors for a differential amplifier for example. Actual value doesn't matter much, as long as they are equal.
Of course more accuracy is better and it's to be proven if the short term stability is there or if the extra digits are just noise.
--- Quote from: CosteC on July 21, 2023, 07:21:41 am ---Possibly Uni-Trend is planning other model in same box with increased accuracy, even on "the same" hardware. Thier sweet secret however will be how they select and age references or exact tolerances and quality of components.
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That would make sense to me. Could indeed be selection or just the accuracy of adjustment.
kloetpatra:
--- Quote from: CosteC on July 19, 2023, 08:22:15 pm ---Can you test it on say, rectangular waveform instead of sine?
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Yes, but I am not sure how well the Keithley will perform as a reference. Also I don't want to consider crest factor errors.
--- Quote from: shakalnokturn on July 20, 2023, 12:49:47 am ---Don't forget that this is a simple comparison of the readings of 2 multimeters, while the Keithley seems reputable enough and frequencies low enough (at the that point) to stick with kloetpatra's statement that the uni-pee is good up to 1kHz (mV) and 10kHz (V) (sine), we don't know enough about the test setup nor have a known reference to say that one meter or the other is reading high or low into the MHz...
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True! Unfortunately I do not have any calibration standard. I only have two Keithley 2000 and one calibrated Keithley 2015. The Keithleys should be in spec up to 300 kHz. As AC source (sine) I used the 2015 source output up to 20 kHz (Accuracy: ±(0.3% of setting + 5mV)). For higher frequencies I had to use a Rigol DS1074Z source output which is specified as ±(2% of the setting value + 1 mV), but also seems to do better than specified according to the readings. Due to relocation I only had access to banana leads so higher frequencies can not be tested. Anyway the UT117C AC V reading drops to zero for frequencies > 1.5 MHz.
--- Quote from: sonpul on July 20, 2023, 04:20:27 am ---kloetpatraHow do you create such charts?
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The chart was made quick and dirty using anychart javscript library https://playground.anychart.com/h4rynMDs
I also did some DCV mesaurement comparison of the Keithleys using a AD584KH precision reference.
The shown deviation is in regard to the AD584KH chinese factory calibration values written on the back.
sonpul:
It seems to me that soon the dissatisfied will write a petition to the manufacturer so that they spoil their Uni-T UT117C to the 0.3% declared in the specifications. :)
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