[evlatests] Bz error for antenna 24

[Rick Perley]

    I ran a long overnight phase stability test -- searching for a 
number of things. 

    An unexpected early result is that there is a very large error in Bz 
for antenna 24.  For two sources, separated by only 5 degrees (at 36.5 
and 41.5 degrees declination), the phases are different by 100 degrees 
for a wavelength of 20 cm. 
    My back of the envelope estimate is that we have a 10-cm error in Bz 
(only -- the temporal stability is very good).  I don't know the sign 
convention, so don't know the sign of this correction.  The higher 
declination source has the larger phase.   Presumably a typo in some 
table somewhere ...

    Rick