[evlatests] evla tests, Aug 25 2005

[Ken Sowinski]

                            EVLA Tests
                          August 25, 2005

The level setting software in the downconverter MIBs was intalled
Wednesday and verified today.  It works in all IFs but D , the 
downconverter for which has no power detectors.  It was verified
that -33 dBm output indication provides correct power level to the
samplers for all IFs and all bands.  Antenna 14 was tested manually 
and in general it was found that -33 dBm overdrives the sampler;
sometimes by a factor of 3 or 4.

Barry worked on using the CMP to setup VLA antennas and found lots
of little things that are being corrected.

A sequence of observations in polarization line modes (both PA and PB)
were attempted to try to get data to characterize the sensitivity of
the antennas at each band.  The L band and C band data should be little
affected by pointing errors.  In each case sampler statistics were 
looked at to verify optimal power levels to the samplers before the
data was taken.  There were strong birdies seen in autocorrelation in
16A and 16D at all bands.  These were not present in 14 and did not
show up in the 14 x 16 cross correlations.  They must originiate in or
after the downconverters.

20 51 20  Start X band PA.  16 has large crossed hand pol'n products.
20 55 00  Start PB. 
20 58 40  Stop.

21 23 10  Start C band PA.  14C is weaker than others for no obvious reason.
21 28 20  Start PB.
21 33 40  Stop.

22 03 40  Start L band PA.
22 08 40  Start PB.
22 13 00  Stop.

K band was still not all working.  16D and 14BD are all without
total power at the T5.  Delays and optimal attenuator setting 
were found for the working IFs.  Before doing the sensitivity
test and attempt was made to improve the pointing of antenna 16 by 
accounting for the tilt error measured last week in the pad tilt 
rather than the antenna tilt terms.  This did not seem to improve
things but was left in place for the K band measurement.

22 58 30  Start K band PA.
23 05 00  Start PB.  Only 16B is likely to have any data.
23 07 00  Stop.


Claire's time tonight will be used to try to measure pointing again.
Both antennas will be used, and having learned caution it will be
done at L band.