[evlatests] P-band status

[Rick Perley]

    The test just reported on provides a 'status summary' for P-band:

    1) All antennas except ea17 and ea21 fringed.  I know that ea21 has 
no dipole (and probably no receiver).  ea17 was the worst behaved in my 
'flux density' test from last month.  Either it is completely broken, or 
has been removed for repairs.

    2) All antennas have consistent polarization now -- no IF-swapping 
was required.  However, the cross-polarizations remain very high. 

    3) Zero-mean PDif values (just noise) were found on ea10, ea11, 
ea13, ea19 and ea25. 

    4) Bad PDif values (meaning, unstable, or just plain crazy, but not 
zero-mean) were found on ea02L and ea12L.  (ea12L also gives highly 
variable gains -- probably the problem is in the amplifier, not in the 
switched power). 

    5) ea28's PDif is very noisy, on both polarizations.  Perhaps this 
is related to the incorrect power levels (wrong by a factor of two)?  
(But I can't see why).