[evlatests] EVLA Behavior, 7 May

[Rick Perley]

    The first half of the test run today produced a few useful results.  
Data were filled with all flags off. 

    P-Band:

    Antennas 14, 17, 21 and 23 all fringing on four IFs.  Initial (first 
30 seconds) behavior odd -- details best shown, not described. 

    L-Band:

    All 9 antennas fringing nicely. 
    Last (0.416 sec) record low.
    Curious amplitude ramps (amplitude about 3%) visible on some 
antennas, not on others. 
    Lots of 'short shallow drops' on antenna 17, 24, and 26, IFs B and D. 
    Antenna 14C still doing the 150 degree jump thing -- but only a few 
percent of the time is spent in the alternate phase state.
    Antenna 26, IFs B and D show a new phenomenon -- a 140 degree phase 
jump, whose characteristics look just like that on 14C -- except this 
one is 10 degrees shallower, and it occurs on both polarizations 
simultaneously.  Less than 10% of the time is in the alternate state. 
    Antenna 24 sensitivity very very poor.  Antennas 13, 14 and 17 are 
poorer than expected.  Antennas 18 and 26 are very good.
    Initial 30 seconds of data very odd. 

    C-Band:

    Antennas 16, 21, 23 and 26 gave no fringes. 
    Initial 30 seconds data very odd -- again, only a plot can show this 
adequately. 
    Sensitivity very good on all working EVLA antennas. 


    NB:  In general, the 'initial records' quality and flagging issues 
are seen only at P, L, and C bands. 

    X-Band: 

    All 9 antennas working well. 
    Only 26, A and C, show the 'short shallow drops'. 
    All sensitivities are about expected level. 
    All initial records are fine -- only the first second of data needed 
flagging. 

    K-Band:

    Only first second of data needed flagging. 
    8 antennas working -- no fringes from antenna 23. 
    Sensitivity of antenna 24 very poor.  13, 14, and 17 are lower than 
they should be.  Antennas 18 and 26 are excellent.