[evlatests] K band at antenna 23

[Ken Sowinski]

Antenna 23 works at K band.  It did not at first because
there was an FRM fault at the subreflector was in the
wrong position; a reset fixed that.  Delays, focus and
pointing are all in reasonable shape.  Pointing should
be could enough for the next collimation pointing run.
Relative G/T is at least as good as the best VLA antennas.
Better pointing would not make it any worse.  If B power
level might not be as stable as we would like.  Walter
set the attenuator levels yesterday, but today it was
inappropriate.  I saw TP and SD varying by a factor of
two over seconds, but later it settled down.  We should
watch it for a while to see if it was merely a burble or
is a chronic problem.

Antenna 18 works at K band, but seems to have lost its
noise diodes.  SD is 0.0 for all four IFs.  I have turned
off the Tsys correction for K band until it works again.