[evlatests] EVLA Phase Problem

[Rick Perley]

    I ran another holography test last night (to test appropriate modes 
for measuring L-band far-out sidelobes).  All antenna moves are exactly 
as expected.  However, a particular phase issue was noted:

    For one of the ten-second measurements (at approximately the 
half-power point of the main beam), all the EVLA antennas jumped in 
phase.  We would normally blame the Flukes here, but in this case, this 
cannot be, for:

    *** Each EVLA antenna jumped by a different amount ***

    The jumps were the same in opposite polarizations for IF#1.  (IF#2 
was not used in this experiment). 

    Jump amounts varied from +80 degrees (Antenna 14, on E16) to +160 
(26, on N40).  Negative jumps were seen on three antennas.  No clear 
corrrelation with antenna number, arm, or distance, is seen.