[evlatests] (no subject)

[ksowinsk at aoc.nrao.edu]

                      EVLA Tests, Aug 11 2005

Jim and Jerry got through with the antenna a little after noon.
Two of the DTS modules needed a little more coaxing beore they
were happy.

The major lesson today was that the FRM was out of order and was
ignoring our commmands; it happened to be at the C band position
so L and especially X looked very bad.  Bob Broilo went out and
convinced it to work again.  A summary of what works and don't:
L band:  All four IFS work
C band:  A, C work; B, D not
         There seems to be adequate power at the downconverters
         and samplers for BD, but no power at the T5s.
X band:  All four IFs work
K band:  IFs C, D work A, B not
         But the pol'ns are swapped in both IF pairs.  Only
         IF C has enough power to keeb the T5 ALC happy even
         though there is a correlated signal from D.

Delays were tuned for 50 MHz continuum at X band, but not the 
other bands.

We took some data at X band to try to establish the bandpasses
to give Mike something to work with.  There are four 3 minutes
scans at 50 MHz BW, one with each IF, followed by four more scans 
at 25 MHz BW.  I adjusted the C IF downconverter attenuator during 
the first IF C scan; believe the data only after 22:01:10.  Delays
were set for 50 MHz bandwidth; the apparant delay change at 25 MHz
due the phase response was about -20 ns for all four IFs.