[evlatests] C-Band Behavior

[Rick Perley]

    C-Band results for EVLA antennas 13, 14 and 16 from today's test are 
as follows:

    Amplitude and phase stability are fabulous, with short-term 
amplitude fluctuations
of typically 0.2%.  Phases are totally dominated by atmospheric 
variations. 
    Antenna 13, IFs B and D are doing the same thing as noted in the 
L-band report.
A small dropout, separated by 10 seconds, but not every ten-second 
interval.  For
the  C-band data, the dropout occurred 'on the 3s' (13, 23, 33 seconds, 
etc.) 

    Bandpasses, delays, etc. are fine. 

    Sensitivity:  Generally superb.  Typical VLA antennas have weights 
of 3 to 5
(these values are proportional to [efficiency/Tsys]^2).  Good ones are 6 
to 8. 
Antenna 13 has weights from 8 to 11.  Antenna 14 is also 8 to 11 (except 
IF 'C',
which is only 1.0, so is clearly not right).  Antenna 16 is 6 to 9.5 -- 
not as good,
so we'll have to look into this.  These numbers are verified by real 
noise data. 

    The elevation dependence of sensitivity is small (by VLA L-band 
standards), but there is
some hint that the EVLA elevation dependence is greater than that of the 
VLA. 
We'll need to look into this with further tests.