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LeCroy or Tek scope?

Discussion in 'Electronic Design' started by Klaus Bahner, Mar 5, 2004.

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  1. That's right. At which point everyone said Anritsu made great spectrum
    analysers - or was it network analysers? No matter. So one assumes
    they make great scopes as well. :)
     
  2. John Larkin

    John Larkin Guest


    A tek 7000-series scope (especially a 7104) can do magical things. The
    7A22 differential input and the 7A13 diff comparator plugins are
    fantastic for working with analog stuff in situations where a digital
    scope would only show fuzz.

    John
     
  3. John Fields

    John Fields Guest

     
  4. Nico Coesel

    Nico Coesel Guest

    One of the important things to look for on a scope is peak-detection.
    The LeCroy scope (I think 9000 series) thats at my employer's lab
    isn't capable of doing peak detection which means it won't capture
    glitches at lower sweep rates. This is a severe limitation.
     
  5. PaulCsouls

    PaulCsouls Guest


    I had a 500 MHz HP I loved. It was a model just before the changed the
    name to Agilent. I demoed one of their hybrid scope, logic analyzers
    which I liked and was much simpler to use than those HP linux
    analyzers. LeCroy I always found counter intuitive. Ya can't go wrong
    with a Tek scope though. They always seem to do what they're supposed
    to.

    Scope are expensive, demo them. Call some salesmen and try some out.
    It's fun.

    Paul
     
  6. Nico Coesel

    Nico Coesel Guest

    Which model? I'm quite satisfied with the Agilent 54622D.
     
  7. I read in sci.electronics.design that PaulCsouls
    The Tek rep that came to see me was 6 ft 8 in tall. Luckily, he believed
    me when I explained about budget limitations. (;-)
     
  8. The next scope I buy I'd like to have a 1Ghz bandwidth. I'm only
    interested in analogue stuff. My current scope is a 50Mhz Tek so it's
    quite a jump. Is the design and functionality of a 1Ghz model going to
    be fundamentally the same or am I in for an unpleasant surprise and
    period of readjustment?
     
  9. John Larkin

    John Larkin Guest

    Old Tek 7104 (or rackmount 7103) scopes are fairly cheap these days on
    ebay. They're 1 GHz analog scopes with microchannel plate CRTs, so you
    can see a single sweep in room light at 5 ns/cm or so. They are big,
    and take all the very cool 7A-series plugins, which are wonderful for
    low-level (audio etc) work too. The only annoyance is the automatic
    CRT blanking timer that protects the MCP, but you soon learn to whack
    that with your thumb without hardly thinking about it.

    7904's (500 MHz, conventional CRT) are nice and even cheaper.

    They behave just like any other analog scope, except the 1 GHz plugin
    (7A29) is single channel and only has 50 ohm inputs.

    John
     
  10. Tim Shoppa

    Tim Shoppa Guest

    I've been using LeCroy stuff in first NIM bins and then CAMAC crates for a
    long time. They are a fairly recent (late 80's? early 90's?) entrant into
    the DSO field but they are solidly in the high-end there.

    Tim.
     
  11. Oliver Betz

    Oliver Betz Guest

    In a TDS3012B I found several nasty software bugs, some of them still
    existing. For example, under certain circumstances a math result (e.g.
    multiplication for power measurement) was scaled *2 or /2 - I don't
    remember exactly.

    Tektronix was not very cooperative, and tried to tell me that some of
    my reports were not a bug, but a feature. Well, the 3012B is "low
    cost", maybe error reports of a 5054B are handled better.

    I guess that's the problem of most "modern" stuff where "innovation"
    is more important than reliability.

    Oliver
     
  12. Jim Yanik

    Jim Yanik Guest

    When buying a TEK scope,be sure to check out the Long Term Product Support
    for that model;last I recall,it was 6 yrs after being dropped from current
    production.(which happens very frequently as TEK brings out new models,even
    if an "A" version replaces that model.)
    But the LTPS periods have been shortening,and may now be even less than 6
    yrs.

    Once the LTPS period expires,you'll get NO support from TEK except for
    calibration,and they don't (or did not) include full schematics in their
    "service" manuals.The TDS scopes are intended for module exchange repair
    only,and once LTPS expires,that goes away.
    Then you're on your own for repairs.
     
  13. Jim Yanik

    Jim Yanik Guest

    The 7904A BW will usually extend out to almost 1 Ghz. with a 7A29 PI.(It's
    basically a 7104 without the MCP CRT.)
    On any 1Ghz scope,you will need more expensive probes,and connections to
    circuits becomes more complicated,if you want to retain the BW and not have
    ringing.TEK has a lot of good stuff for this in their scope accessories
    pages.
     
  14. Jim Yanik

    Jim Yanik Guest

    TEK service "support" is no longer what it used to be.
    They laid off(Rif'd) most of the service support staff several years ago;
    "there's no money in it" in their opinion.
     
  15. CBarn24050

    CBarn24050 Guest

    It's sign of the times and will only get worse. The problem is the boards are
    made by machine and tested by computer. Once a product run is over the boards
    are no longer repairable so once stocks run out, thats it.
     
  16. Guy Macon

    Guy Macon Guest

    In the long run, it's often cheaper to buy three of something than
    to buy one and then, several years later, try to get it fixed.

    The problem with doing that is that it assumes that the product
    will meet future needs. Computers are an obvious case; by the
    time the old one breaks down it's time to upgrade anyway. Scopes
    are just the opposite; you will still be measuring waveforms many
    years from now.
     
  17. I read in sci.electronics.design that Guy Macon <[email protected]?.guymacon.com>
    I used to tell people that about vinyl disc records, but hardly anyone
    listened, even though you can't 'fix' a damaged vinyl disc.
     
  18. What causes the false appearance of ringing on a scope trace? Is it
    just simply the ground loop created by the earth wire or something
    more?
     
  19. BFoelsch

    BFoelsch Guest

    Good scopes don't ring, but probes are an art form unto themselves. A good
    probe with a long ground wire will ring, a cheap probe will ring even when
    grounded directly at the tip.

    Once you can view above about 50MHz bandwidth, ANY length of ground (earth)
    lead will ring on suitably fast edges. Using an adapter that couples the
    ground directly to the tip is the only way to have a chance of seeing what
    the circuit is really doing. If you have a poorly designed probe, even that
    won't help!

    The other big "gotcha" is the probe input impedance. Just for giggles,
    calculate the impedance of a 15 pF probe at 100 MHz.

    I've been researching and measuring the performance of "commodity" scope
    probes with curious results. Some are poor, some aren't bad at all, but I
    have yet to find one that truly compares to the Tek probes. Some of the PMK
    probes are electrically very good, but the mechanics, features and
    construction are awful.

    Anybody have a "favorite" brand of passive probe they can suggest?
     
  20. maxfoo

    maxfoo Guest

    Make your own.

    I use a sma-sma dc-block and a ~0.085 semi-rigid coax with an sma connector on
    one end. The other end's ground shield is stripped back an 1/8 inch exposing the
    center conductor. This is a "RF Sniffer". DC block I use is good up to 18ghz.







    Remove "HeadFromButt", before replying by email.
     
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