EEVblog Electronics Community Forum
Products => Test Equipment => Topic started by: drummerdimitri on February 19, 2015, 03:36:31 pm
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Hello,
My fluke 289 was last calibrated on the 22nd of october 2011.
Fluke recommends a yearly calibration for this device but I am having a hard time justifying the 100$ yearly expense of doing so.
I will have my meter calibrate because it's been nearly 4 years since it was last calibrated but from my understanding precision remains it is just the accuracy that it adjusted am I right?
Also, can I get away with calibrating once every two or three years? How can I tell the difference in accuracy so I can justify the cost?
Thanks!
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Do you have a reference voltage to test it with?
VoltageStandard (http://) offers multiple versions. For example, the VREF-01 sells for $25.50, which is rather reasonable. Models with extra features and/or higher precision go up to $285.00.
I find that it's not generally necessary to calibrate meters and such for hobbyist use, but it is nice to have a reference voltage source to be sure they're not off the deep end (they can be had inexpensively). Also happens to be a lot easier on your wallet too. Nice to have other meters to check against when you get a weird reading as well.
If you start to get really out of whack readings and doesn't require repair (or that a new battery won't fix), then it may be worth getting the meter calibrated, depending on it's value.
Regarding your Fluke, it probably doesn't need it (shouldn't IMHO).
If however you're making a living with it, then getting it calibrated every few years (or more frequently), may be in your best interest (per customer request/directly to meet compliance requirement).
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Fluke makes great gear and so far all my Fluke DMMs stayed in spec for many years (some even decades).
So if you do not need calibration for any business reason and you did not damage/repair it,
there is probably no need to spend 100$ for calibration (which should better be called verification)
because you very likely will just get confirmation, that everything is in spec.
But if you spend the money make sure you at least get all data and not only and document that says "passed"
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Remember that calibration isn't adjusting. Calibration is just verifying that the meter still meets it's stated specs. For the most part the 289 should never go out of adjustment. I would actually wonder if something was broken if the calibration failed.
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I use my Fluke as a hobbyist and not a professional making his money off of it so yearly calibrations is out of the question.
I'd be interested in knowing by how much the meter's readings change with time so I know if It needs calibrating or not.
I would like it to be accurate within two decimal places with voltages up to 30V for example.
Also, can I use a voltage reference from some electronic device around the house? Not willing to buy a voltage reference.
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I dont think there is any reference around the house.
I have multiple Flukes at work and at home. Some are over 20 years old and NONE ever failed calibration. The only tools I have that ever needed adjustment where an >20 year old scope and function generator. So I won't waste my money on calibration (even though it's free at work :-+).
My work gear is calibrated yearly, but its used a lot and I do use my gear to adjust and test other (custom) gear.
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I made a simple Voltage check reference using a MAX6126AASA25+ (0.02%) reference I/C. They cost around $10 (US) each. You only need 2 or 3 extra parts from memory, I used the circuit shown in their data sheet.
Only having a 2.5 Voltage as a reference won't be the same as a lab cal, but if you mostly check low DC Voltages it is handy.
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I have a fluke289. I have many beefs about this meter, but accuracy and drift is not one of them! it is several years old, and still measures in-spec when compared to a handful of voltage and resistance standards.
But a more important question to ask yourself is this.
If you are measuring something as 30.00V, but that it turns out (how would you know??) that in reality the measurement was 30.03V, does that really matter? Bragging rights asside, I suggest it matters not one tinker's cuss.
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@LawrenceW, what did you not like about the 289, I had been looking at one?
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VK5RC,
WELL!....
The meter chews through six AA batteries in double quick time (several weeks). I have a 15+year old FLuke, which I think is only on it's second 9V battery!
The screen contrast is really poor. Much worse than even a cheap meter. It's a fine-pitch LCD pixel display, not a big chunky 7 segment one. The backlight doesn't really help any, and only contributes to the poor battery life.
It takes about 7 seconds to boot up. Seven. Seconds. That's an age! Especially when you want a quick measurement NOW. So what? Well, because of the power consumption, I find myslef instinctively switching the thing off after a few seconds. So that's ANOTHER seven seconds when I decide I need to take another reading...
Too big to fit comfortably in one hand, so it ends up being a bench meter. But for a Bench meter, I prefer my Kiethley 2000.
The onscreen graphical trending display of readings over time, is (just about) better than nothing. Ideally, you need to download any data that the meter captures to your PC. For this, Fluke are happy to SELL you a piece of software called FLukeView Forms. And this costs slightly in excess of the annual GDP of several south African countries. Combined.
Some things are buried down sub menus. It's a meter! I want to just grab a reading, not engage it in a dialogue.
Look, it does everything the spec says it should, it's accurate and the resolution is good (50,000 count). But it's just not my go-to meter for anything. I think a Fluke 87 V would have been a better bet, for me.
These are my opinions. Others' opinions may differ, but that doesn't change my views, I am afraid.
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The meter chews through six AA batteries in double quick time (several weeks). I have a 15+year old FLuke, which I think is only on it's second 9V battery!
I don't have a Fluke 287/289, but yes, the battery consumption is rated at 100 hours minimum and 200 hours in logging mode.
I have a 187 and it is rated at 72 hours with 4 AA. I use nimh Eneloop AA cells and it runs fine.
The 70 series multimeter is rated 2000 hours on a standard 9v alkaline battery. The Fluke 87 I has a battery life of 500 hours and the 87 V has a battery life of 400 hours.
So yes, there is a huge difference in battery life. All quoted battery hours are straight from the user manuals.
It takes about 7 seconds to boot up.
Yes, I have read that as well. If you just want a quick reading, the 289 probably won't be your first choice. The 187 boots instantaneously.
The 289 also has a potential problem with its supercap and you need a firmware upgrade to fix the IR problem.
https://www.eevblog.com/forum/testgear/fluke-189-with-leaking-surface-mount-coin-cell/ (https://www.eevblog.com/forum/testgear/fluke-189-with-leaking-surface-mount-coin-cell/)
https://www.youtube.com/watch?v=VySoQ5CLmF0 (https://www.youtube.com/watch?v=VySoQ5CLmF0)
https://www.youtube.com/watch?v=16hXJukpGiI (https://www.youtube.com/watch?v=16hXJukpGiI)
With respect to the two problems above, if you buy a new Fluke 289 from an authorized dealer, both problems are likely to be solved with the newest pcb/firmware from the factory. If you buy an used 289, then you might need to fix these on your own?
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Look, it does everything the spec says it should, it's accurate and the resolution is good (50,000 count). But it's just not my go-to meter for anything. I think a Fluke 87 V would have been a better bet, for me.
I picked one up from Ebay and agree completely. Its a great meter, but no way in hell would I want it to be my only meter. There are a whole bunch of frictions involved in turning it on and navigating through the menus. Using it for routine measurements feels like a chore.
Its a great second meter though.
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Also, can I get away with calibrating once every two or three years? How can I tell the difference in accuracy so I can justify the cost?
That depends on how important the calibration is to you.
What you need is some sort of reference to check it against. Precision voltage reference ICs are cheap enough, get yourself one (eg. http://www.ti.com/product/ref102 (http://www.ti.com/product/ref102) or whatever precision you need - look around)
You can also get a precision resistor. They're quite expensive to buy new but I've bought second hand ones on eBay and had no problems (yep, second hand resistors on eBay... ;) )
http://www.ebay.com/sch/i.html?_nkw=0.01%25+metal+foil+resistor (http://www.ebay.com/sch/i.html?_nkw=0.01%25+metal+foil+resistor)
Put a couple of things like that on a little PCB and you can have a lot more confidence in your equipment for very little money.
OTOH if you're selling things where there might be some liability you should get yourself a proper calibration + certificate.
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@lawrenceW, thanks, one of my pet dislikes is viewing angle, invariably when I really need to read the dmm there is stuff all over the bench, the dmm is just out of reach, off angle and I have to read it now!
Otherwise the 289 looks pretty good really.
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Yes, RetiredCaps is quite right about the firmware upgrade and leaking backup battery, both of which I had to fix myself. I am sure that these issues would not apply to newer instruments.
The "100 hours" run time is not a figure I've ever obtained, however, as the meter sips juice, even when switched "off". I tried Eneloop Rechargeable AA batteries, but becauase they only start at 1.2V and run down from there, the elapsed time between recharges was quite short, making frequent recharges more of a pain!
It's not all bad news! If the meter tells me that my supply voltage is 5.056V, or that the resistor value is 10.045K, I can be pretty damn sure that it is.
But going RIGHT BACK to your first question, you need to ask yourself - "does it really matter whether that 5V rail is around 56mV high, or that my 10K resistor is indeed within its rated 1% tolerance, or not? Most times, the answer is "no". But, being curious engineers, sometimes we just like to know!
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I have a Fluke 867B that is still well within spec.
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VK5RC,
WELL!....
The meter chews through six AA batteries in double quick time (several weeks). I have a 15+year old FLuke, which I think is only on it's second 9V battery!
The screen contrast is really poor. Much worse than even a cheap meter. It's a fine-pitch LCD pixel display, not a big chunky 7 segment one. The backlight doesn't really help any, and only contributes to the poor battery life.
It takes about 7 seconds to boot up. Seven. Seconds. That's an age! Especially when you want a quick measurement NOW. So what? Well, because of the power consumption, I find myslef instinctively switching the thing off after a few seconds. So that's ANOTHER seven seconds when I decide I need to take another reading...
Too big to fit comfortably in one hand, so it ends up being a bench meter. But for a Bench meter, I prefer my Kiethley 2000.
The onscreen graphical trending display of readings over time, is (just about) better than nothing. Ideally, you need to download any data that the meter captures to your PC. For this, Fluke are happy to SELL you a piece of software called FLukeView Forms. And this costs slightly in excess of the annual GDP of several south African countries. Combined.
Some things are buried down sub menus. It's a meter! I want to just grab a reading, not engage it in a dialogue.
Look, it does everything the spec says it should, it's accurate and the resolution is good (50,000 count). But it's just not my go-to meter for anything. I think a Fluke 87 V would have been a better bet, for me.
These are my opinions. Others' opinions may differ, but that doesn't change my views, I am afraid.
Off-topic:
I have the same meter (well, 287) and agree with all of your points. This results in me not using it as often as my other meters, which is a shame. But I will pull it out to cross-check because I trust it more than my other handheld meters. The plus is the batteries last forever in a unit you barely use :P.
I still find the on-screen logging display useful and do use it. And in case you lost the FlukeView forms software, I posted a thread recently on how you can restore it for free. ;)