VLA Test/Observation Coordination Meeting
                           B.G. Clark
                          May 19, 2005

1.  EVLA

R. Perley now understands the efficiency measurements at K band after
correcting for the finite opacity of the atmosphere.  The K band feed
is small enough to hold a nitrogen-cooled load over it, as well as the
usual hot load, calibrating the switching cals.  The receiver temperature
is about 20 K over its entire frequency range.  Separating out the 
atmosphere he finds that there is an additional 12 K contribution to
the system temperature coming from above the mouth of the feed, extrapolated
to zero atmosphere.  (3 K from the microwave background.  The rest comes
from scattered radiation from the feed legs to ground or possibly from
reflection losses.)  It is very difficult to do total power measurements
at this band because of the variable sky.  However, an attempted measurement
gave a deflection of 11% of system on Jupiter, which would give an efficiency
of 50%, with a large uncertainty.

The previous L band measurements (on antenna 13) have been repeated on 
antenna 14.  Zenith temperature is about 30 K across the whole 1425-1975
MHz band.  Antenna 13 showed increasing efficiency toward the high end of
the band, a poorly measured 55% at 1975.  The antenna 14 measurements are
well determined, but seem to show only 45% at the top of the band.

K band is showing a very large loss in correlation coefficient, perhaps
an order of magnitude.  The origin of the loss has not been determined.
Phase noise measurements on the LOs tentatively indicate that LO purity
is not a problem.

K. Sowinski reports that antenna 14 pointing is now working much better,
but is not yet understood.  There is a sign error in applying corrections
when observing over-the-top, but even when solutions are restricted to 
elevations below 90d, the post-fit residuals are larger than other antennas.
There is clearly an unmodeled or incorrectly modeled term in the pointing.

2. 196 MHz system.

R. Perley reports that they managed to get the UNM channel 9 digital TV
station turned off for a few hours, and find that with that done, interference
seems to be present but manageable.  There is a problem with the calibration
system - it is completely unusable on antenna 6, and, taken at face value
on the other three antennas, indicates an antenna efficiency of 15%, 
unbelievably low.  J. Ulvestad complains that the impact on VLA engineers
and technicians has been much higher than projected, and since Chris 
Carilli will be gone for the summer, the project seems way too short on 
scientific guidance.

3.  Long Wavelength Demonstration Array

The array station (or patch, or element, whatever) to be located on the 
VLA site is nearly ready to begin construction.  This will be 256 dual
polarized dipoles in the 30-80 MHz range.