Fluke MM Calibration

william1981

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Good Day All

I hope this is in the correct group for this question?

i need some advise, I received a Fluke 77 DMM and i was told i need to send it for calibration.
so here is my questions:
were do i send the meter for calibration, who can do this?
how much do they charge for this service?
can this be done by myself with some sort of accuracy? 

Thanks
 

Shonver

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What makes you think your meter needs a calibration? The only thing that goes wrong with these meters is if it becomes defective. But it is not something that "goes out of tune". What is commonly called calibration is nothing more than verification that the meter works within specification. Proper calibration entails submission to a lab, and that is not cheap. Not for private persons. I recommend doing a verification test against a known good meter. If the readings you obtain are similar, you are good to go. The only time a meter requires calibration is in a professional situation where uncertainty of calibration can have legal implications. Then you will need calibration by a certified lab, traceable to the national standard.

FYI, in some decades of experience in a manufacturing environment where the meters were in use daily, no Fluke meter ever failed calibration.
 

Family_Dog

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I think I also have a Fluke 77 amongst my motley collection, but as Shawn states above, there should be no need for re-calibration. They either work or they don't. And being Fluke, this means they usually work quite well. If it is the old grey DMM that I am thinking of, it was an excellent meter at the time, it just plods on and on.


-F_D
 

chrisc

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Get a selection of 1% resistors and check that the display is correct

I also make sure that the leads and plugs are clean.  A squirt of contact cleaner and a lappie does the trick and a cotton bud in the socket
 

d0dja

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Something that's always bothered my about my Fluke 117 is that it feels like it needs calibration ... in that on the mV setting with nothing connected it'll sti at about 20mV; and on resistance if I touch the probes directly to each other I get ~0.3 ohms.

Is this normal behaviour? I've had it for about 10 years... been consistently like this.
 

DACMan1

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d0dja said:
Something that's always bothered my about my Fluke 117 is that it feels like it needs calibration ... in that on the mV setting with nothing connected it'll sti at about 20mV; and on resistance if I touch the probes directly to each other I get ~0.3 ohms.

Is this normal behaviour? I've had it for about 10 years... been consistently like this.
It is fairly normal, the input is very high impedance, so 20mV is probably what it is measuring; and 0.3Ohm is in a normal range for test leads. What is the mV reading when you short out the leads?

Normally calibration is only necessary for qualification of equipment. Say you have to write a report for something, you will have to prove that the equipment used to do the measurements is calibrated. Where calibration typically only remains valid for 12 months.
 

william1981

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sorry correction my meter i got from my father is a Fluke 75 and i have just tested a couple of 9v battery's and it was spot on to the measurements i got from my other MM, i am going measure a couple of 1% resistors next but thanks for all the inputs this far.
 

d0dja

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DACMan1 said:
It is fairly normal, the input is very high impedance, so 20mV is probably what it is measuring; and 0.3Ohm is in a normal range for test leads. What is the mV reading when you short out the leads?

Good to know. I've always assumed that the .3R is leads, because I suppose DMM manufacturer can't assume that you'd be using their leads and pre-emptively calibrate for that.

It makes sense on the ~20mV being an artefact of noise and sampling electronics on the high impedance inputs, as on VAC it hops around 20mV, on VDC it's zero, on mVAC it's 2mV or so.

 

kolakidd

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I don't know if they have branches in other places, but Comtest in Johannesburg has an official Fluke and Amprobe calibration service, it's walk in, and reasonable when I did my calibrations around two years ago. They may be able to advise on closer calibration places.
 

william1981

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So i got a quote for calibration on my Fluke 75 and it will cost me R460,
at this stage i am in 2 minds on sending it in, if i take a 9v battery and take readings from the Fluke and from my Midas MM i am getting 0.1 - 0.17v difference, from the 2 I suspect it will go higher with higher voltages.
 

Shonver

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Maybe someone close to you with a meter of similar calibre to your Fluke will be willing to do a comparison. Unless you are using the meter to do calibrations, the observed variance you posted above will be of minimal consequence. It's about 2%, but worth checking against something better than "Midas".
 

kolakidd

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It?s a question of peace of mind. Removing a variable. When you?re measuring something critical and it seems out of whack you don?t want to be worrying if it?s the multimeter, that can end up costing more.

Also, when they calibrate it?s not at a single value, it?s across a range.
 

william1981

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the Midas meter i bought because of the big LED screen that works well if you are half blind lol
but yes to take out the question is my meter giving me the correct reading on any of the other measurable values is the big one for me, i dont us it for any other reason then on my amps and pre-amp readings but i still would like with some degree of accuracy that what i am seeing on the one side is the same or close to the same on the other side.
 
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