Fluke 189: it is possible to calibrate it "at home"?

Uhm.. I've read the manual...and I think that isn't possible... :-(

See threads , titled Digital Voltmeter Calibration and also Calibrate source how? both last year

-- Diverse Devices, Southampton, England electronic hints and repair briefs , schematics/manuals list on

N Cook wrote: [SNIP]

Ok, thank you a lot. I'm sorry for this question : I don't know that you have already spoken about this argument, I' m Italian (as you can see reading my post in poor englih!) and I don't read often this newsgroup...!

Thank you a lot!!

Che cosa li incita a pensarli per avere bisogno di di calibrare il vostro tester? E quanto esatto deve essere?

Ehi! Un altro italiano?? Italiano o sei stato in Italia? Ok, I prefer to write in English, so also the other readers can understand (..I think..but with my language probably is not simple!!) My problem is that I need a general purpose, unique, affordable meter. I had read that Fluke produces very good meter, but I have also read that our calibration center - in Italy- ask over 100 Euros for a calibration of a meter. You can understand that it is a problem for me (I'm a student..)..especially when I read that "Accuracy is specified for a period of one year after calibration". Probably, it is a cautelative operation....but is very expensive, too... Moreover, if I buy a meter that is declared for "0,025% precision" in DC measurement (example)...well...I'm spending a lot of money for a "almost perfect" meter..and I don't want use it out of calibration... To use a tester out of calibration after a year, I buy a cheaper "Meterman" for about 100 $ (that I have read is also a good meter..)..and when it start to be out of calibration, I change it... So, this is my problem. I don't want to buy a meter that, after two years of random usage, need a calibration that cost about 40% of its total cost...

I own a 20 year old Fluke 77 that for all practical purposes is as measurement precise as I need it to be. Buy a used meter and don't worry about it.

:-) Ok, I'm watching some auction on Ebay. But, you don't have answero to my question: why do you speak Italian? Are you italian, or you had used babylon translator? :-)

On Wed, 14 Mar 2007 21:07:18 +0100, "Starflex" put finger to keyboard and composed:

You can build your own single-chip precision voltage reference using Maxim's MAX6350 (5.0V) or MAX6325 (2.5V):

"The MAX6325/MAX6341/MAX6350 are low-noise, precision voltage references with extremely low, 0.5ppm/°C typical temperature coefficients and excellent, ±0.02% initial accuracy. These devices feature buried-zener technology for lowest noise performance. Load-regulation specifications are guaranteed for source and sink currents up to 15mA. Excellent line and load regulation and low output impedance at high frequencies make them ideal for high-resolution data-conversion systems up to 16 bits."

- Franc Zabkar

Ok, I had seen this chip, thank you for the link!

to

I would suggest a precision source like that plus a high precision resistor to check your meter against, once a year , noting the results in a record, also cross-checking all 3 with someone else's calibrated meter every now and then , also recorded.

-- Diverse Devices, Southampton, England electronic hints and repair briefs , schematics/manuals list on

You have the two choices already mentioned:

1. Compare your meter readings to those of a meter known to be calibrated.

1. Build an accurate voltage source.

In either case, you need only note the error and record it on a label stuck to the back of the meter. In those very rare instances in which the instrument's ultimate accuracy is required, simply correct the reading using the recorded information.

I understand your concern, but I believe that digital multimeters tend to hold their calibration extremely well, even with "rough" handling and the passage of many years. It is quite unusual, but certainly not impossible, that one will require recalibration. Meters given away as promotional items by distributors (i.e., very cheap meters) compare very favorably in accuracy with Wavetek, Fluke, and HP instruments.

There are other reasons to purchase quality instruments, of course.

Good luck.

Chuck

----== Posted via Newsfeeds.Com - Unlimited-Unrestricted-Secure Usenet News==----

----= East and West-Coast Server Farms - Total Privacy via Encryption =----

Depends on what you want to do with it. If you're in an industrial situaiton, you don't have much choice but to have it professionally calibrated...whether it needs it or not. In the US, when ISO9000 started, management looked at the cost of continuous calibration of EVERY peice of equipment in the plant and dumped everything that wasn't absolutely necessary. Was a great couple of years for hobbyists.

As for actual calibration...most of the time, if you stay away from the bleeding edge of specs...a modern 3.x digit multimeter is always in calibration or it's broke bad. If you have two different types of meters, check them against one another. IF they're the same, they're PROBABLY both ok.

Of course, all bets are off if someone has tried to "calibrate it" without proper tools and experience.

Simplest thing is to checkit against another meter and not worry about it. You'll want to do this at least once when you buy a used meter. If you build calibration sources, then you have to worry about their calibration.

For most of us, accuracy ain't what it's cracked up to be. I have two 5.5 digit meters in the attic. Found I never needed the resolution and all the noise in the last digits was more distracting than helpful. When you want to know if a 9V battery is good, you don't need much precision or accuracy. mike

You will not be able to calibrate the meter yourself at home. You would need the proper set-up and proper calibration references for the particular voltage ranges (AC and DC), and the precision resistance references. These reference units also follow scheduled calibrations.

When considering the new price of a Fluke meter and its reputation for precision and performance, the calibration cost is worth it. Fluke meters are an industry standard.

Ideally, the meter, or any precision electronic test instrument should be calibrated once a year. But, for general use it can go a long time without re-calibration if it is used in an environment where it is not knocked around or abused.

In the lab where I work, we are having our instruments calibrated according to their manufacture schedules. We must to this in order to maintain our high standard of calibrating and checking our customer's devices. We have some devices for measuring UV intensity that have to be calibrated every 6 months because of safety issues.

--

JANA _____

Ehi! Un altro italiano?? Italiano o sei stato in Italia? Ok, I prefer to write in English, so also the other readers can understand (..I think..but with my language probably is not simple!!) My problem is that I need a general purpose, unique, affordable meter. I had read that Fluke produces very good meter, but I have also read that our calibration center - in Italy- ask over 100 Euros for a calibration of a meter. You can understand that it is a problem for me (I'm a student..)..especially when I read that "Accuracy is specified for a period of one year after calibration". Probably, it is a cautelative operation....but is very expensive, too... Moreover, if I buy a meter that is declared for "0,025% precision" in DC measurement (example)...well...I'm spending a lot of money for a "almost perfect" meter..and I don't want use it out of calibration... To use a tester out of calibration after a year, I buy a cheaper "Meterman" for about 100 $ (that I have read is also a good meter..)..and when it start to be out of calibration, I change it... So, this is my problem. I don't want to buy a meter that, after two years of random usage, need a calibration that cost about 40% of its total cost...

If you're talking about human safety issues, or some military spec stuff,

But you can do pretty good yourself at home. There are many circuits available that show how to build (or buy) very accurate voltage references. Precision resistors can be purchased for quite affordable prices.

If it's just your home lab, a few tenths of a percent of accuracy is probably OK.