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nice DVM

Discussion in 'Electronic Design' started by John Larkin, Sep 20, 2007.

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  1. Joerg

    Joerg Guest

    I love the Eico tube voltmeter on my bench. Nearly indestructable.

    Model 232, for connoisseurs.
     
  2. Jim Yanik

    Jim Yanik Guest

    but only 3% accurate,IIRC. and -analog- display.
    The 34401A is 1000x more accurate.
     
  3. 100nV resolution is like black magic to a VTVM.


    Best regards,
    Spehro Pefhany
     
  4. John Larkin

    John Larkin Guest

    The 34401A had the display digits, down into the nV, but the last few
    were mostly random numbers. The VF display kicked huge spikes out the
    input terminals. Instead of fixing it, they mucked the firmware to
    make AC readings drop to zero somewhere not too far south of 1 mV. And
    I always found the menus confusing.

    John
     
  5. Robert Baer

    Robert Baer Guest

    And that is supposed to mean that Fluke is not??
    30 years ago when i worked in the Cal lab at Ford Aero Space, we
    received 20 Fluke bench DVMs (do not remember model number) for incoming
    inspection, and they all were within one-tenth of the datasheet spec!
    And they did not change much the next two years.
    That is to say, they could have been used as secondary standards.

    The Fluke is speced to 6.5 digits, has better resolution, has more
    ranges, etc than the Keithley meter.
    I did not check the AC specs between the meters, but i think that
    100nV resolution and 4% accuracy at 300Khz is not too shabby.
     
  6. Jim Yanik

    Jim Yanik Guest

    What did I say to have you think that?
    When I said "Keithley is a reputable company.",I meant that they support
    their products,even those made for them in Taiwan.They've been around for a
    LONG time,too.

    So,what did YOU mean with "You get what you pay for..." ??
    Are you implying that Kiethley is NOT a reputable company?


    And that was THIRTY YEARS AGO.
    Fluke is certainly not the same company today.
    HP isn't,nor Tektronix.
     
  7. Joerg

    Joerg Guest

    But a staunch 5kV spike out of a defibrillator test rack can be like
    death to a DVM while the VTVM doesn't even flinch.
     
  8. John Larkin

    John Larkin Guest

    Well, like the doctor said, don't do that!

    John
     
  9. Joerg

    Joerg Guest

    Sometimes s..t happens. Just had that in the lab. Transistor croaked for
    no apparent reason and, whaddabam, three instruments are toast. Will be
    repaired but not today since the missus wants me to tune the piano
    first. She'll treat me to my favorite dish tonight, Rouladen. That kind
    of sealed the deal.
     
  10. Robert Baer

    Robert Baer Guest

    I think that Fluke has been around for a long time also, so
    neglecting one company by mentioning a different one does seem to "diss"...

    The price of the Kiethley meter is a fair amount less than the price
    for the Fluke meter - and what one gets (ranges and resolution) is a lot
    less for the Kiethley WRT the Fluke meter.
    So..you get what you pay for.
     
  11. Robert Baer

    Robert Baer Guest

    Good old Shakespeare..does not quit.
    Tubes may have a little glow at high voltage, but robust as all heck.
    And it takes a hell of a lot of RF to swamp them, but not much to
    kill operations of semiconductor products.
     

  12. Modern switchers are a LOT less "noisy" Than they were back in the days
    when you were taught that they were far "more noisy".
     
  13. Terry Given

    Terry Given Guest

    modern switchers, like everything else, tend to be optimised for minimum
    cost. 3dB below the EMC limits is good enough. 6dB is massive overkill.
    Sad, but true.

    Cheers
    Terry
     
  14. I think the term "massive" is what is overkill here.

    Sure, those made by shit companies, and I don't care what their yearly
    gross is, there are plenty of "name brand", shit quality companies out
    there.

    Made by premier companies, however, one can even compete on price if
    one jumps into an industry making it good as well as less costly to begin
    with.

    In other words, all those twits out there that buy a PS based on a
    name, get single sided, mass produced technology, and pay a premium price
    for the name. SOME companies make a premium product, get that same price
    as the "premium priced, name brand" assholes, and deliver the premier
    product with double sided (or more) technology, superior shielding (even
    at the circuit level, one element from another), and just because they
    are lower volume than the big boys does not mean that such products do
    not exist, nor that the technology has not advanced over the single
    sided, same old shit, ropa-dopa twits.
     
  15. John Larkin

    John Larkin Guest

    We use switcher warts for all our digital delay generators and
    fiberoptic gadgets, and get jitters in the single digits of
    picoseconds. It's not all that many dB separating switcher noise from
    all the other crud floating around these days.

    John
     
  16. John Larkin

    John Larkin Guest


    OK, let's take your VTVM, and my handheld Fluke, and drop them from
    equal heights onto a hard floor.

    I had an Eico 221 when I was a kid, built from a kit, $26 from Allied.
    All the really cool kids had Eico's, and the jerks bought Heathkits
    or, horrors, RCA.

    John
     
  17. Terry Given

    Terry Given Guest

    indeed. I was appalled to do a job last year, for a company that makes
    LED lamps for Philips. Man was that stuff crap.
    the trick, of course, is finding these organisations. but yes, they do
    exist.

    Cheers
    Terry
     
  18. Joerg

    Joerg Guest

    Sure but that becomes a nightmare when you have to hold laser diodes
    stable to tens of femtometers. Luckily it's not as bad as in S.F. here
    although one client resides near an unmarked building with lots of
    shortwave antennas on top. That had caused some grief when measuring
    stuff. The good thing is most people use spread spectrum these days so
    the noise can be dealt with easier. Another client is next to a busy
    runway. That'll be a challenge in a few weeks so I'll be staying the
    weekend hoping it'll be less busy with freighters and all that.
     
  19. Joerg

    Joerg Guest

    I meant electrically. I wonder what your Fluke would say if a
    defibrillator jolt accidentally arced over into the probes. Euro
    strength, meaning 5kV out of a 32uF cap via some inductors. I have seen
    innocent looking electronics explode when that happened.

    My Heathkit dipmeter holds up pretty well, around 30 years now. Ok,
    their overall quality wasn't quite up to par with Eico IMHO. Except on
    ham radio transceivers and stuff, those were very sturdy.
     
  20. Joel Kolstad

    Joel Kolstad Guest

    Sounds like the typical big-company scenario where most of all the good
    technical people are long gone, but the name still holds marketing value, so
    they contract out to the lowest bidder to build new devices with little idea
    of whether or not what they're getting is junk.
     
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