[evlatests] general confusion

[Ken Sowinski]

All the antennas came and went many times today for many
reasons.  The confusion was so massive it hardly seems
possible, or worth, documenting.

In the end we are back in the state where all the antennas
work as well as we have been accustomed to expect and Rick
will use the last hour to verify that the newly fixed L302s
are really fixed and to further investigate the X band
birdies now that two downconverters have been "insulated".

The only known problem at the moment is that 16BD does
not work at Q band.  This has been the case for many weeks,
but it also seems to be intermittent.


Antenna 18 K band still does not work.  Feed aliginment was
checked and found to be (by third hand report) within half
an inch of where it should be: that cannot account for no
fringes.  I wondered if somehow the AC and BD IF pairs have
been swapped, but swapping swapping sky frequency between IF
pairs did not do it.  By the time 18 was available again, it
was too late to try to organize a test with a water maser.
Yesterday a hot load was placed over the feed and a respectable
system temperature of 60 K was deduced from the T5 SD deflection,
so we definitely have a connection from the sky, through the
K band system, to the backend.


As previously reported, antenna 24 was still quite weak in
IF C this morning.  After Rob visited to install the second
L302 the antenna was coaxed back into service again and two
changes were seen.  IF C was no longer very weak, but comparable
to IF A.  And, IF A did not work properly until a delay change
off -300 ns was introduced.  That is about the delay through
the transition module bandpass equalization filter but setting
and bypassing that filter for 24A made no difference to the
correlated signal.  The delay for IF C did not change at all.


An attempt to verify interband collimations was thwarted by an
ill-prepared file and confusion from running two executors.
Barry was at the VLA running an executor using VLA antennas
in subarray 2 to sleuth out CMP timing problems.