[evlatests] Antenna issues from 28 July

[Rick Perley]

    Some interesting oddities occurred during the 5-hour run on 3C286, 
last Tuesday night:

    1) Antennas 3 and 23 have a large residual phase wind -- 3 to 3.5 
turns over the 5 hours.  No other antenna has a net phase slope. 
    2) Antenna 2 showed a 50% drop in visibility phase over the last 
hour -- this was a smooth drop, as if  pointing had wandered off 
somewhat.  No other antenna had any such effect. 
    3) Antenna 25 had numerous stepwise amplitude gain changes -- the 
ratio of the highest to lowest is a factor of 2 (equivalently, a factor 
of four in power).  These changes were accompanied by distinct changes 
in bandpass ripple.  Are we sure the attenuators weren't changing on 
this antenna?