[evlatests] antenna 23

[Ken Sowinski]

Rob called a little while ago and said that antenna 23 ought
to work with IFs A, B and D; C would be unavailable because
he was going to return the D303 to Socorro.  He was two-thirds
right.

Total power in IF B was a bit weak; I updated the attenuator
setting in the database from 9 to 3 dB.  IFs A and B both
looked reasonable then and delays were set.  IFs C, as expected,
and D did not work.  However I found that the output attenuator
in the T304-D was not connected to the IF D sampler.  Further
examination showed that the T304-C was connected to the IF D
sampler.  I wonder if some of the confusion with C and D is
because of this miswiring between downconverter and samplers?

I started a long track on 3C345 beginning at 2356 IAT to try to
assess the stability of antenna 23.  All the EVLA antennas were
included and claim to be working.  There was a burble at IAT
midnight which is surely due to the Modcmops.  I cursorily
watched the data go by sampling the baselin of antenna 6 with 23
and so only one interesting event at 00:06:20 IAT which changed
the phases for both IFs A and B.  Someone should examine the
data with more care to see if it was all EVLA antennas or just
antenna 23.  I also saw variations in amplitude of about five
percent on a time of minutes.  Again a more careful examination
is needed.