[evlatests] antenna 13 moved

[Ken Sowinski]

It moved, but there are mysteries.

Shortly after it was set down and connected I was able
to get it to work and determine the delay for the new
pad.  It was about what we would expect given the OTDR
measurement.  C and X bands were checked and worked
except at IF C which did not fringe at all though there
was power and a SD signal at the T5.  I suspected the
deformatter, but poking at it did not seem to help.

A little later it was seen to work very poorly at X band
and the symptoms were of a large delay error.  I spent
some time trying to track this down and only succeeded
in confusing myself.  What I think I know know is that
with the delay set as I determined it earlier:
C band AC is fine;
C band BD is consistent with a large delay error (100 ns or more);
X band AC is about as good as C band BD; and,
X band BD is much worse than that.
I also know that no other bands were looked at, and that
no other EVLA antennas were tried.

It certainly smells like software to me, but no hypotheses
come to mind yet.  I gave up out of tiredness and impending
startup.  Tomorrow during SW time I will try to go about this
more systematically to learn what is happening.


I am sure Rob can tell us more, but it looks like antenna
24 is ready to try tomorrow with IFs A and C.  I propose to
delay testing antenna 24  until I am sure that there are no
system problems plagueing us.