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Calibration Of Electronic Equipment In The Home Workshop

Discussion in 'Electronic Repair' started by Too_Many_Tools, Mar 1, 2007.

  1. Jim Yanik

    Jim Yanik Guest

    Then there's the Fluke differential voltmeters,that have nearly infinite
    impedance at null. ISTR a HP diff VM that had a 100Meg Z on it's off-null
    mode.Then there are Keithley hi-Z meters,with gigohm input Zs.
  2. Robert Baer

    Robert Baer Guest

  3. Robert Baer

    Robert Baer Guest

    Wouldn't be neat to have a handheld differential voltmeter?
  4. MassiveProng

    MassiveProng Guest

    NO! I said that when you get your gear calibrated, it is typically
    ONLY a verification of a good instrument.

    Being off cal usually means something is awry.

    What you are paying for is a VERY nice standard and a comparison
    check against it. Of the hundreds of calibration sessions that we
    have had done IN our lab, as opposed to sending the gear out, it was
    done without them ever opening a single instrument.
  5. MassiveProng

    MassiveProng Guest

    Lemmie guess... An RCA Master Volt Ohmist?

    I still have one of those as well.

    Have a couple Heathkit MMs around too.
  6. Pretty close to the same thing to me.
    IOW you didn't turn any screws, you just checked it.
  7. Yeah, but it's not as good looking as the other one though. I just recently
    saw another really nice, big analog meter that someone sells. It wasn't
    cheap either, but I can't recall where I saw it. I was thinking it was in
    my Jameco catalog, but I can't seem to find it in there. It looked allot
    like the older ones.
  8. MassiveProng

    MassiveProng Guest

    That is 99.999% of the time ALL they do.

    That would be worldwide practice.
  9. Jim Yanik

    Jim Yanik Guest

    why do you need that accuracy in a handheld instrument?
  10. Jim Yanik

    Jim Yanik Guest

    I would say "accurate,traceable standard".
    If it meets all specs,then there is no need for adjustment.

    In fact,you might make it worse by tweaking on adjustments.
    (some pots or trim caps on older instruments freeze in place and turning
    them breaks them or they become noisy)

    Instruments that have been adjusted have to be rechecked,as some
    adjustments interact with others.Trying to "optimize" a range may throw
    another range or ranges out of spec.
  11. clifto

    clifto Guest

    I don't *need* a Ferrari, but it would be neat to have one.
  12. MassiveProng

    MassiveProng Guest

    All great reasons to abide 100% with my original reply.

    So there, Too Much Toolessness!, you fucking RETARD!.
  13. Jim Yanik

    Jim Yanik Guest

    well,precision lab instruments are used in lab conditions,with at least 15
    minute warmup times to allow the unit to stabilize,and to expect that
    accuracy in a handheld that would be used in non-lab
    doesn't make sense.

    BTW,when calibrating precision instruments,the unit under test has to warm
    up and stabilize for 20 minutes minimum,and the lab has a controlled
    temperature and humidity,usually 73+/-2 degF. Of course,your lab standards
    have already been powered up and stabilized for the proper time.
    Insturments used outside of specified temps were derated in accuracy.

    I worked in a USAF depot-level primary standards lab.(PMEL)
    (before repairing and calibrating for Tektronix for 21.5 yrs.)
    My lab (L.G. Hanscom Fld) did the MIT-Lincoln Labs instruments,besides the
    usual USAF stuff,covered Pease,Otis,and other military bases.
  14. Robert Baer

    Robert Baer Guest

    Someone asked the same question about a pocket scope.
    I guess there are times and conditions when such "esoteric" equipment
    would be nice to have.
  15. Palinurus

    Palinurus Guest

    Odd, I've been working in a cal lab for the last few years, and I'd say
    a good 10% of what we get has something wrong with it. Some of it is
    designed-in problems, but most of the rest is due to impact damage or
    contamination. Our customers are largely the petrochemical industries
    along the Gulf Coast, and they apparently believe that if a piece of
    gear can't survive a 1 meter fall onto concrete, or being rained on and
    rattling around in the back of a pickup truck for a few weeks, than
    there's obviously something wrong with it anyway. It makes for a good
    business in replacing switching, connectors and cracked LCDs.
  16. MassiveProng

    MassiveProng Guest

    Ahhhh... the "nice" factor.

    I think it would be nice to have a nice Agilent spectrum analyser,
    or network analyser, but I don't have $60+k for each right now.

    Maybe after I win the lottery.
  17. MassiveProng

    MassiveProng Guest

    Which distinctly falls under the category of REPAIR, NOT
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