[evlatests] Switched Power Effectiveness at Ku-band

[Rick Perley]

    Same intro as for X-band.  Results are:

    1) Application of PDif corrected all non-smooth variations seen in 
the raw visibilities, *except* for ea25.  See below.

    2) ea25 is weird.  Scan to scan gain variations are seen in the raw 
visibilities.  Variations are also seen in the PDif values.  For all 
other antennas, these are perfectly correlated.  On this antenna, they 
are not!  Application of the PDif did correct some of the observed 
variations, but not all.  (The variations are of the order of 10% -- 
quite significant). 

    3) We expect an antenna temperature of 3.2 K from 3C84.  This is 
beautifully seen on all the equipped Ku-band antennas.  The only notable 
issue is that the system temperature of ea21 is rather high -- 35 to 40K 
(when 25K seems to be the average for the rest).