[evlatests] Global Phase Jumps upon scan change

[Rick Perley]

    A short test was run, in which I observed 3C286 in continuum, at P, 
L, C, and X bands.  There were 5 scans at each band, in succession, to 
see if 'global' phase jumps occur at scan change, with no changes in BW, 
frequency, mode, or source.  Results:

    1)  At P-band, the phases of all EVLA antennas change upon every 
scan change, on all four IFs.  The sizes of the phase change are 
different between IF1 and IF2. 

    2) At L-band, the phase changes only for IF #1 upon a scan change. 

    3) At C and X bands, there are no changes in phase upon change of 
scan. 

    As always, it is not possible to tell if it's the VLA or EVLA which 
is responsible. 

    In addition to this, the phase behavior of antenna 12 (a VLA 
antenna) is quite bizarre.   It is wandering all around, on IFs A and C.