[evlatests] Switched power Quick-Look

[Rick Perley]

    A hour-long correlator test for Ken, done at noon today, utilized 
all bands.  I took a quick look at the data to see if there are any 
major problems with switched power. 

    There are only a very few serious issues found:

    1) L-band: 

    ea23C:  The PDif values vary by +/- 300 millicounts, on second 
timescales, while the mean value is about 100 millicounts (close to 
normal).  The others IFs of this antenna are fine. 

    ea25C and D:  PDif is zero to within the noise (a few millicounts). 

    2) S-band:

    ea06A:  The long-standing issues of variable PDif remains.  The 
values change by >10 percent on timescales of ten seconds or so.  The 
variation is smooth, but there is not a single timescale.  The effect is 
absolutely *not* due to variable gains, as the fringe power is steady.  
All other IFs from this antenna, at this band, are fine. 

    ea16A:  Same issue as for ea06A, but much less strong. 

    That's All!  All other antennas at all other bands give good, 
seemingly reliable PDif and PSum data.