[evlatests] More phenomenology

[Rick Perley]

    1) The lack of fringes from antenna 14 in our Friday morning test data
is now understood.  Bob and I left the antenna F/R controller in 'manual'. 
(We were doing Q-band efficiency tests in the afternoon). 
   
    2) A closer look at the spectral line data, for antenna 16 from that
dataset provides one more curious observation:

    The peculiar (but small) gain effects noted yesterday in the
continuum data (i.e., the 4% square-wave-like gain changes on
47 second timescales in 16A, etc.) are *not present* in the spectral
line data.  All gain solutions -- done on a 3.3 second average -- for
all IFs are fluctuations perfectly consistent with VLA antennas. 

    There is a 10% gradual loss in gain, occurring smoothly over
the 4-hour duration -- which looks like the effects of pointing errors,
but these are supposed to be long gone!  The effect is identical in
all IFs.  One scan on 3C84 has a 5% loss in gain over 15 minutes,
again seen on all IFs. 

    Otherwise, all phenomena are as described yesterday. 

    Incidentally -- spectral bandpasses were derived for all four
IFs (these data were at 12.5 Mhz BW), showing a
~20 -- 30 degree phase residual across the bandpass.