[evlatests] 4-band and P-band report

[Rick Perley]

    I ran a full system check (all bands, all antennas) yesterday 
evening.  Here I report on the low frequency bands. 

    A)  74 MHz (4-band)

    No EVLA antennas gave fringes.  Antennas 17 and 23 gave no fringes 
-- as expected, as 23 is on the MP, and 17 is in the barn.  All other 
antennas gave good fringes, with correct polarization. 

    B)  327 MHz (P-band)

    EVLA antennas 14 and 18 gave good fringes.  Antennas 13, 16, 24 and 
26 did not -- as expected.  As noted above, antennas 17 and 23 gave no 
fringes, as expected.  All others gave good stable fringes. 
    I checked the sensitivities via AIPS weights.  Antennas 3 and 19 are 
quite poor, a factor of ~2 below normal in G/T.  EVLA antenna 18 is 
poorer than nominal by a factor ~1.5.  EVLA antenna 14 is very good.  
All others are at nominal. 
    The cause of the poor sensitivities was easily determined -- all 
three have very high X-polarization, approaching 100% (meaning that the 
fringe amplitude in the X-hand correlations is about equal to that in 
the parallel hand).  This means that one of the dipoles is not 
electrically connected to the hybrid polarizer.