[evlatests] November 22 2005 Tests

[Ken Sowinski]

                          EVLA Tests
                      November 22, 2005

The major accomplishment today is that Mike installed the FPGA firmware 
in the deformatters for IFs A and C in both antennas; the B and D 
deformatters were left unmodified.  After delays were corrected at 
C and X bands the system was given to Rick to see if he could see any 
difference.  A quick check of the SD as a function of Gain in the 
deformatter suggests that the range over which the SD volatage is 
maximized has not changed much.  A more careful check will have to be 
done later.

After Rick's observation the remainder of the deformatters were
modified.  Delays were tuned at all bands and IFs and appear to be
reasonable at the moment.

No correlated signal was seen from the Q band system just installed
in antenna 16.  When the levels are set properly the SD looks fine.  
Pointing was tried at a narrow continuum bandwidth, but still there was 
no hint of fringes.  Is it possible that something is miswired between 
the receiver and the UX converter?  If not, we point at the sun and look 
for the total power deflection.

In the waning minutes a quick check was made of G/T.  The most 
salient result is that 16 looks pretty good at C band: RCP is a
little better than LCP, but there are many worse VLA antennas.

It was noted that the attenuators in the downconverter are no longer
all set optimally.  We will have to make a pass through this again
sometime when we do not have array time.