[evlatests] Big delay change, antennas 27

[Rick Perley]

       In reducing my 3C273 data (for the '4M' project), I note that 
antenna 27 suffered a remarkable change in delay about 6 hours into the 
run.  At L-band, the delay, on all IFs, changed by 13 nsec, while the 
amplitude appears to be little affected.  At X-band, the antenna fringe 
power dropped dramatically at that time.  There is nothing in the log 
about anything happening.

    For reference, the date was 07 April, and the time of the sudden 
change was between 07:50 and 07:56, IAT.