[evlatests] system summary

[Ken Sowinski]

Some time was spent today seeing what works and doing a little
tuning.

L, C and X bands seem to be in good order.

Antenna 17 seems dead at K band.  There looks to be no receiver
probelm but it is perfectly incoherent which leads me to suspect
the L301-1 is not working, but telling us it is OK.

Antennas 3 and 22 are still flagged at Q band because the F12
is not reporting the right lock bits.  Attenuators for 17 BD
were adjusted a little.

Antenna 26 is still very weak at Q band.  A raster should be
done to see if we are peaked on a sidelobe.  Focus and delays
look to be OK, so if it is not pointing it has to be a very
bad receiver.

Except as already noted, both K band and Q band look reasonable
when referenced pointing is used.

P band looks good.  14AC is dead.  Again I suspect one of the
synthesizers.  VLA antenna 4, IF B is erratic.  Backend total
power and sync det fluctuate a lot, but the FE looks OK.
Antennas 13 and 16 don't work, but we don't expect them to.


Some oddities.  While Barry was testing setting of the analog sum
control bits the array seemed to go incoherent for 30 seconds
beginning at 20h35m50 IAT.  No explanation is offered; the
correlator log stream had nothing in it at that time.

It is still often the case that VLA antennas do not set up when
a script is begun.  We experimented with the 'hardware reset'
command, but that did not work either.  It was clearly seen to
arrive at the CMP, but the hardware was unaffected.  I want to
investigate whether deferred commands are tossed if the CMP things
the command execution time has already passed.  Still unexplained
is why the execution time should already be past, if it is not why
the CMP should think that it is.