[evlatests] Broken Switched Power on ea27C at Ka-band

[Rick Perley]

     The Feb 05 and Feb 14 elevation test gave good switched power 
data.  From these, I can list the antennas/IFs/polarizations which are 
clearly broken.

     It's a short list -- one, and only one, entry.

     ea27C has no useful switched power at Ka band -- the values are 
nearly constant at a low (noise) level, and are actually negative.  But 
the PSum (digital power) is fine.   This was the case on both days.

    There are, as usual, lots of 'oddities'.  But only two stand out for 
report:

     ea05 at X band -- the PDif values are highly irregular, and are not 
reflected in the visibility data.

     ea23 at X-band -- there is a remarkable 3-hour periodicity in the 
switched power data -- and these reflect real gain changes. Although 
visible in all four IFs, the effect is much stronger in the A/C pair, on 
both days, especially in LCP.  The variation is seen in Tsys as well as 
in PDif and PSum -- this means it's not simply a gain effect.  The 
fractional variation is larger in PSum than in PDif.