• Main INDEX
  • Monthly INDEX
  • PREV
  • NEXT

    User name R. Michaels

    Log entry time 13:38:05 on October29,2007

    Entry number 210456

    keyword=trig. cleanup, redundant scaler reads

    There's been a concern about a too-high rate on L-arm. I don't
    see anything wrong with the trigger, but I'd worry about double
    pulsing at scaler, e.g. from unterminated cable. Scaler input looked
    very clean for T3 and T4. Looked on 25 nsec scale up to 1 usec scale.
    No extra features or reflections.

    However ! The module which fed the scalers (a PS 757) did have a
    reflection caused by the coax handshake cable. This cable was
    properly terminated but there is evidently some flakiness on the
    connector on the R-arm. What I did: I moved this cable to another
    fanout module which is fed by the 1st fanout. The 1st fanout feeds
    the scalers and trig. super. directly. This 2nd fanout should help
    buffer the reflections. As for what happened during runs, one can
    guess that the scope with 50 ohm termination changes the picture,
    so may well have been reflections. FWIW, looks very clean now.

    I did the same thing for T4: send a buffered copy to R-arm.

    Now T1,T2,T3,T4 are all readout on chan 1-4 of the norm. scalers
    on both HRS. I used Coax 1,2,3,5 for these resp. (coax 4 is busted).