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Cable interface for HP 54120A/B to 54121a test set.

Discussion in 'Electronic Equipment' started by Don W, Sep 22, 2004.

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  1. Don W

    Don W Guest

    Does anyone know where I can find an interface cable for the HP 54120A/B Mainframe oscilloscope.
    The interface cable attaches a test set such as a 54121a. AFAIK HP no longer manufactures the cables.

    The interface looks like one of the older Centronix SCSI connectors. Does anyone know what the
    pinout on the cable is, or where to find it?

    Also--looking for 54120t or 54121t HP original manuals. I've got Xerox copies from Manuals Plus,
    but would like to find the printed copies or someone that has them in PDF form.


    Don W.
  2. Hi Don,

    i've just disconnect the cable that connects my HP 54120B with
    the 54124A Test Set.
    I have measured Pin for Pin and they are connectet straightforward,
    Pin 1 is connected to Pin 1 ; Pin 2 to Pin 2 and so on and so on.
    I have opened one Connector and have looked inside,
    it's just a ordinary 50 pole gray flat 3M Ribbon cable, exept it's
    screened, but it looks like the screen is hand made by HP,
    wrapped around copper mesh which is connected to the metal housing
    of the plug.
    It looks to me that you can build your own cable by using
    those 50 pole cable and plugs, and to wrap around some kind of
    screen, i think that will work.
    I hope that helps you a bit,


    For direct reply please remove all the " x " in the mail adress.
  3. Don W

    Don W Guest

    Hi Jorgen,

    Thanks for your post. I suspected that the cables might be straight through, but thought it better
    to find specs, than to end up messing up my units. I bought a 54120B, and a 54121a (20Ghz) test set
    through Ebay, and they came without the cable. Now I'm trying to get them working together so that
    I can use the set to test some Microwave equipement that I'm designing.

    How do you like your 54124t set? Have you used it up through its max bandwidth (50Ghz)?

    Don W.
  4. Hello Don,

    i like that scope very, but til now i havn't used the
    Very High Bandwidth Inputs.
    Mostly used the TDR and the other 3.5mm Input.
    I hope for you that the units are all OK and no input is blown,
    this could be very expensive...
    How much have you paied at ebay for those fine pices?

  5. Don W

    Don W Guest

    Hi Jorgen,

    I bought two mainframes from different individuals. One is a 54120A, and the other a 54120B. I
    also bought two test sets from a company. They are both 54121a's. I'm hoping that at least one of
    my test sets will prove to be completely working. If not, the IC's were still available from
    Agilent last time I checked their website. I've checked out the mainframes, and both appear to be
    working fine as far as I can tell without connecting up the test sets. I had access to a similar
    setup while working at Cypress Semiconductor, and liked it a lot. We used it for edge jitter
    analysis on some SONET parts that we were designing.

    I've seen 54120(a/b) mainframes bring anywhere from $500 to $1500 USD on Ebay, while complete units
    with a mainframe and test set tested are bringing ~$3500 USD. The only test sets that I've seen so
    far are the ones that I bought, and I paid about $500 USD each for them. Of course, that is with no
    guarantee that they are in working condition, so I may have more invested in them by the time they
    are working and calibrated. My first issue to resolve is getting them connected together with the
    interface cables. Those cables were no longer available from HP/Agilent.

    Don W.
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