[evlatests] X-band over the weekend

[Ken Sowinski]

Rick reported:
>     3) On Sunday afternoon, things were not so good.  Antennas 13 and
> 18 gave close to normal amplitudes against VLA antennas.  Antenna 16
> was down by a factor of 10,  and antenna 14 down by a factor of 3.  But
> these two were o.k. with each other.  Do we have timing problems again? 

This was also happening late Saturday night during the pointing run.

However by Monday morning during POLCAL all the EVLA antennas in use
(13, 14, and 16) looked normal once again.  The default explanation
is that timing had slipped up again for a while.  If this should 
happen again a diagnostic for a timing error is to turn off phase
switching and see if the data is correct.