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

Discussion in 'Electronic Repair' started by Starflex, Mar 14, 2007.

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  1. Starflex

    Starflex Guest

    Hello!
    As you can read in my previous post, I'm watching for some meter...
    I had found some Fluke's used meter..but I have some doubts about its
    calibration: if I buy a meter that had lost its calibration, is posible to
    "recalibrate" it at home, or I must ship it to a proper center?
    Thank you!
     
  2. Starflex

    Starflex Guest

    [SNIP]

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

    N Cook Guest

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

    Starflex Guest

    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!!
     
  5. Meat Plow

    Meat Plow Guest

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

    Starflex Guest

    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...
     
  7. Meat Plow

    Meat Plow Guest

    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.
     
  8. Starflex

    Starflex Guest

    :)
    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? :)
     
  9. Franc Zabkar

    Franc Zabkar Guest

    You can build your own single-chip precision voltage reference using
    Maxim's MAX6350 (5.0V) or MAX6325 (2.5V):
    http://pdfserv.maxim-ic.com/en/ds/MAX6325-MAX6350.pdf

    "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
     
  10. Starflex

    Starflex Guest

    Ok, I had seen this chip, thank you for the link!
     
  11. N Cook

    N Cook Guest

    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.
     
  12. chuck

    chuck Guest

    You have the two choices already mentioned:

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

    2. 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
     
  13. mike

    mike Guest

    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
     
  14. JANA

    JANA Guest

    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...
     
  15. You will not be able to calibrate the meter yourself at home. You would need
    If you're talking about human safety issues, or some military spec stuff,
    3rd-party calibration certification is probably required.

    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.
     
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