[evlatests] Switched Power Review -- A Truly Great Result

[Rick Perley]

    It has been a few months since I last reviewed the status of our 
switched power calibration system, for all antennas and all bands.  The 
'stress test' run this morning provided an opportunity for a systematic 
review.   Only ea14 was out of the array.   All other provided good PSum 
and PDif data at all bands. 

    Bottom Line:  Only one antenna, at one band, in one polarization, 
gave a non-usable switched power:

                  ea16, in RCP, (IFs A and B) had zero-mean (just noise) 
PDif. 

    All other switched power data looked great! 

    A secondary, but still important, and definitely intriguing result 
is this:

                ea06 and ea16, at S-band, did *not* give the oscillatory 
PDif values that I saw in every other S-band database that I've ever 
looked at (and that is over 100 by now).  So what's different here?  One 
thing is that the requantizer gains were set -- but Ken and I agree this 
should have no effect on the switched power.  But maybe it does?  
Another possibility is that ea06 and ea16 were both 'being nice' at the 
time -- the stress test is only at S-band for 3 minutes, and the 
oscillatory phenomenon  is know to change its nature from time to time.  
Another possibility is that the location of the observation (in the far 
north, at declination +78) is free of whatever is bothering ea06 and 
ea16.  But I've reviewed two long runs from the ARCADE project -- 
declination +57, and these showed the phenomenon at full strength. 
              More investigation is warranted, which Ken and I will do.