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Erratic sinewave signal generator?

Discussion in 'Electronic Basics' started by Bill Bowden, Nov 8, 2013.

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  1. Bill Bowden

    Bill Bowden Guest

    I have a Novatech 2901A 32Mhz synthesizer that increments in steps of 1Khz with digital readout from 200Khz to 32Megs. It's a cute little unit but occasionally gets locked up with a grossly distorted waveform and no frequencycontrol. It does a self test when turned on and usually works fine, but sometimes doesn't boot up right, and other times goes into a spasm when I disconnect or reconnect the output using alligator clips. I was thinking it might be a grounding problem since I have the generator connected to a different power strip than the scope. Is it advisable to connect all the instruments to the same power strip to avoid problems like this?

  2. The GROUND must be interconnected.
    Each instrument has a plus/minus supply voltage, or a direct mains
    plug and a signal input or output.
    The signal connectors have a HOT center pin and in most cases
    the other pin is equal to GROUND. Those GROUND must be interconnected,
    ground from the oscilloscope with ground from the signal generator
    and with the ground from the circuit under test.

    Sometimes one can connect the minus power also to ground,
    but not always. Sometimes it is advisable to connect protective earth
    from the mains also to the common ground potential.

    I cannot recommend a general rule, because it depends on the
    devices used and other circumstances.
    If there is a good GROUND network, this will act as a reference point
    or as reference area for electrostatic discharges and high frequency
    noise. Often it is necessary to connect the framework of the workbench
    also to protective earth from the mains.
    The minimum thing to do is to connect all instruments to the same
    protective grounding from the mains outlets.

    Sounds like a wishy-washy recept, but the precise details of your
    setup are impossible to know.

  3. Hmm google has never heard of the Novatech 2901A.
    Re: different power strips. That shouldn't matter. The grounds are 'pretty much' all the same. At the very lowest signal levels I've sometimes seen'ground loop' signals that will change if I plug the 'scope/ instrument into different AC 'branchs'... sometimes worse, sometimes better...

    George H.
  4. Hey I just got this via email.

    Maybe you can contact Novatech and ask them about it.
  5. Bill Bowden

    Bill Bowden Guest

    Yes, good idea, I'll send an email.

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