[evlatests] PDif Survey

[Rick Perley]

    I stole 20 minutes of time this afternoon, to check how antenna 
behavior in fringes and PDif at all bands.
    Antenna 5 and 9 were out of the array.

    Results:

    1) L-band

          ea10 gives no fringe power, but PDif is o.k.
          All antennas gave good PDif.

    2) S-band

          No fringes from ea03 -- no receiver, presumably.
          No fringes from IF1 on ea21 --- but PDif values were fine.
          ea26 was flagged on all four IFs, but the fringes look fine, 
and PDif values were fine.
          All other antennas gave good visibility and PDif.

    3) C-band

         all antenna fringed and gave good PDif.

    4) X-band

         No fringes in 2nd IF from ea 3, 8, 15, 20 and 28 -- presumably 
due to old receivers.
         Zero-mean PDif on  ea02 (all IFs), and ea12D. 

    5) Ku-band

         No fringes (no receiver) on ea03, 8, 15, and 28
         All other antennas gave good fringes and good PDif.

    6)  K-band

         ea21 and ea27 gave no fringes, but both give good PDif on all IFs.
         ea23 and ea25 gave good fringes, but zero-mean PDif on all IFs. 
         All other antennas behaved normally.

    7)  Ka-band

          No fringes (no receivers) on ea03, 08, 15, and 28.
          All other antennas behave normally

    8)  Q-band

          No fringes from ea27, but PDif is present. 
          No fringes, and PDif is zero-mean, from ea08 -- receiver is 
out, I think.
          all other antennas are o.k.

     There is strong evidence that 'set and remember' is not working 
correctly on some antennas (ea20 stood out!), but I'll have to leave 
this report to another day.