[evlatests] Data taken with 20 Hz

[Rick Perley]

    Ken took 40 minutes of data, at X-band, with the 20 Hz synchronous 
power enabled.  He arranged a new scan (but with the same mode -- OSRO1) 
to occur every 40 seconds, to look for scan-induced phase jumps. 

    Results:

    a) No phase jumps were seen associated with any of the scan changes. 

    b) Only one phase jump of any kind was observed: on both the AA and 
CC correlations on antenna 23, about 5 minutes into the test. 

    c) Two '1dB' amplitude jumps were noted, one on antenna/IF 28C, one 
on antenna/IF 25A. 

    d) 26 antennas fringed nicely (6 and 10 are still out of the 
array).  Antenna 4 was about 3 minutes late to get on source.

    e) IFs AC showed now blanks in any polarization.  IFs BD were 
littered with blanks -- not antenna based.  On the LCP side (correlation 
DD), baselines 5 x 8, 13, 15, 17, 21, 24, 25 and 27 were 99% blanked 
(the surviving 1% looked fine).  Also, 2 x 9, 4 x 7, 7 x 9, 8 x 19 and 8 
x 23.  A different set of baselines were absent most data on the BB 
(RCP) correlation. 

    g) Various periodicities were seen in phase -- all periods were 
longer than 40 seconds, and have nothing to do with scan changes.  The 
amplitudes were small (few degrees) -- could be atmosphere? 

    h) Amplitude stability was poorer than expected (variations of 1% or 
so -- my standards are high!).  We await gain correction via switched 
power before offering a speculation as to origin.