[evlatests] status, Aug 24 2006

[Ken Sowinski]

On Thu, 24 Aug 2006, Ken Sowinski wrote:

> I spent some time looking at pointing primarily to get
> Q band to be more robust at antenna 16 and 18.  There was
> a significant focus error at 18 ( the result of a typo)
> and large collimation errors at both antennas.  All this
> has been repaired and 16 and 18 now look quite good at
> Q band.
>
> Except that the BD IFs don't work.  There is power and
> switched power at the T5 but no correlated signal at all.
> All IFs work for 13 and 14, so it is unlikely to be a
> software problem.  All IFs work at K band so it is unlikely
> to be a T303 problem.  Antenna 16 lacks an M301, so it is
> unlikely to be an M301 problem.  All the L302s *claim*
> to be in lock.  I did not try very hard to try to make
> them prove it.  I suspected the transition module parameters
> but trying all combinations of band select and inversion
> was unsuccessful.  There is probably a clue in the fact
> that earlier today 18 BD worked while 18 AC was broken.

Here is another clue to add to the confusion.  Yesterday
morning there was Q band observation in progress using
all the EVLA antennas.  At that time all four IFs worked
in antenna 16; and in antenna 18 AC was dead, but BD was
working.

I still think it could be L302s lying about their lock state.
The next step should be to investigate an L302 when Q band
is not working in some antenna.  Jerry and Rob suggest
commanding it to some distant frequency and then see if
it locks up properly when commanded back to the observing
frequency.