how many years can I expect a fluke multimeter to be within its specs

[45/70]

Hi Major, and welcome to CPF!:thumbsup:

......Sometimes the meters will fall within the specs and sometimes they wont. From my normal customers I would say for the most part atleast one area in the performance test has to be tweaked back into specs per year......

......One thing to consider if your thinking about just buying one cheap meter a year to replace a more expensive option is that how do you know the cheap meter works from the start? It may not be off but yearly or even every two years between calibrations gives you the piece of mind it is right.

Would you say that the likelihood that a meter needs recalibration is the same for less expensive meters vs. higher quality ones, or is the need simply proportionate to the accuracy of the meters? In other words, obviously a meter that is +/- 0.025% +1 is more likely to be out of spec than a meter that is +/- 1% +3, or is it?

I hope that makes sense. I'm in a bit of a "crunch" today.

Dave

 

[desirider]

Hi Major,

Welcome to CPF! It is good to have a calibration expert on-board I am newbie here myself.

Calibration is always fascinating. It is mind boggling how accurate the calibration equipment really are. Even an off-the-shelf Fluke 8846a is accurate to 25-40 ppm! I can only imagine the calibration standards being an order-or-magnitude more accurate.

I have a Fluke 8600A that was made in the 1970s and was used in a lab until the 2002/2003. It was last calibrated in 2002 and I just compared it to my lot-newer Fluke 175 and it is spot on. Can you imagine a 4.5 digit (20,000 count) DMM with a basic DC accuracy of 0.02% designed and built in the 1970s? Heck, even the built-in rechargeable battery works, although there is a good chance that the battery must have been replaced. Still, it is 10 years old!

Cheers,
Desirider.

 

[march.brown]

@ march.brown ... Is the 5.000 Volt (DC) reference the one from voltagestandard ? ... I haven't seen any others.

I bought mine on 17th February 2010 on Ebay ... It was advertised as "Precision Voltage Reference Source 5.000V 0.2%" ... It was certified as 5.0002V at 72F ... It cost $20-15 including postage from the US to the UK ... The Ebay seller was rdana who is actually DanaCo.net ...

I am not sure whether they are still selling these items ... It is a small PCB (30mm X 75mm) with a few components on it plus an ON/OFF switch and a mount for a small 9V (MN1604) battery ... Sorry I can't give you any more information , but it might be worth contacting DanaCo.net.
.

 

[majorm]

Thanks for the welcomes.

45/70: What I was getting at with the HF example was they built it to a more lenient spec. So depending on how wide they made it the meter could stay within that range for a long time. However on that same note with cheaper components did the meter just barely make specs when it was made? Thats where the calibration comes in. It gives you a baseline to go from. Most of the time unless there was damage to the unit a meter will drift out of tolerance. On the voltage ranges many meters will give high readings if they have low battery voltage. So thats something else to consider. Going to your accuracy tolerances that is a gray area since the meter could have fallen right at nominal when it was made or it could fall at the edges. I doubt they adjust the HF meters back into a certain spec unless they just use a couple quick test points. The Fluke however would be more likely to fall closer to nominal due to better components. The thing to think about though is the resolution was the same with your example is that even if the better meter was out even 2x to be generous the tolerance its still potentially more accurate than the cheap one brand new. I hope that made more sense.

NoI'mIm tempted to go buy a HF meter just out of curiosity. They would have to be less than a mile from the office.

desirider: Yep it is an interesting field and hard to believe how close we can create measure and create a certain value. We have a older HP 3458A that we used to use but have a Fluke 8508A too and while the 3458 is just as good in many ways the 8508 is just easier to use. Many of the older pieces of equipment were just built well and still work great. They just usually aren't as user friendly.

 

[Viking]

I bought mine on 17th February 2010 on Ebay ... It was advertised as "Precision Voltage Reference Source 5.000V 0.2%" ... It was certified as 5.0002V at 72F ... It cost $20-15 including postage from the US to the UK ... The Ebay seller was rdana who is actually DanaCo.net ...

I am not sure whether they are still selling these items ... It is a small PCB (30mm X 75mm) with a few components on it plus an ON/OFF switch and a mount for a small 9V (MN1604) battery ... Sorry I can't give you any more information , but it might be worth contacting DanaCo.net.
.

Thanks I didn't found it , but I have found another 5.0000 V DC reference with an accuracy of 0.0025%




@ majorm

Thanks for your post , it was very informative.

And BTW welcome to cpf

 

[somename]

I have a cheap meter that I've been using for the past 8 years as well as a cheap bench top multimeter and a Fluke 179 meter. Noticed the other day was gonna use the cheap one and the voltage reading with it on a 6V lead acid battery was WAY off. Figured its been many years since the battery was changed. New 9V battery and presto, reads right back with the other 2 meters again.

Seems the difference is the Fluke reads consistent all the way till the batteries are completely dead where as the cheap ~$20 meter was reading off without even the low battery light on.

 

[BringerOfLight]

The biggest problem with obtaining a voltage reference is that they are only good once you receive them, for 6 months to a year. Just like DMMs, they have to be checked/calibrated occasionally. I would think this applies to making one yourself.

Yes and no. The primary aging factor with one of those single-chip voltage references will be operating hours. If you only use the reference once a year to calibrate your multimeter, that 0.1% LM4040 will be more than sufficient for your typical 0.5% accurate multimeter for a very, very long time.

BTW, I mentioned the LM4040, not because it's particularly accurate/great, but because it's extremely cheap, easily available, very easy to use and probably accurate enough for 99% of the people...

 

[45/70]

......I hope that made more sense.

Thanks for the explanation, major. I can follow that.

Yes and no. The primary aging factor with one of those single-chip voltage references will be operating hours. If you only use the reference once a year to calibrate your multimeter, that 0.1% LM4040 will be more than sufficient for your typical 0.5% accurate multimeter for a very, very long time.

Understood. As I mentioned in another thread recently, if your serious about measuring Li-Ion cell voltages, my personal preference would be a meter along the lines of 0.1% (or better) DC Volt accuracy. It's not that you couldn't get away with 0.5, or even a 1% meter, but for example the maximum CV voltage (and thus the maximum fully charged voltage) for charging LiCo Li-Ion cells is 4.20 Volts +/- 1%, or ~4.15-4.25 Volts. So with a 1% accuracy meter it's possible that your meter is out of bounds by approximately 0.05 volt either way, if it's at the "edge". On the low end 4.10 Volts is not going to cause any problems. On the high end 4.30 Volts is not likely to either, but if your serious about it......

So anyway, it does make more sense to me now for one to obtain a voltage reference. The relatively low cost of sending one back for checking/recalibrating, as I said, is something I hadn't considered, and does make it a practical solution.

I'm not as OCD about this kinda stuff as I used to be, but as you can probably tell, there's still a hint present.

Dave

 

[Russel]

I just received received a DMMCheck from voltagestandard.com and tested a couple of my better meters. My old Fluke 863 was pretty much dead on. My newer Agilent U1251A was close, but not quite dead on. I don't remember exactly how old the 863 is, but it has never been calibrated in all the years that I have had it. When I get a chance I will post the actual numbers.

 

[Viking]

My newer Agilent U1251A was close, but not quite dead on.

Do you know , if it was still within its specs ?

 

[Russel]

I checked my old Fluke 83 III here at
work, the voltage is good, but the resistance measures pretty far
off. I'll post the numbers for all three meters when I get home
tonight. The DMMCheck standard is a pretty good alternative (I have
no affiliation with voltagestandard.com other than being a customer)
to more expensive meter calibration. I don't really need super
accuracy, but it's good to know how accurate my meters are.

Voltage standard           Fluke 83 III
5.0000V                       5.00 (40V scale)

0.9997mA                    999. micro amps (Rel used, 4000 microamp scale)

999.5 Ohms                .999K (Rel used, 4K scale)

10.005K Ohms              9.91K (40K scale)

100.07K Ohms              89.8K Ohms (400K scale)

Battery 9.52V                Battery 7.87V
                           (no low battery warning)