[evlatests] C-Band performance

[Rick Perley]

    Only antennas 13, 14 and 16 are outfitted at C-band.  All three 
worked well in all four IFs. 

    Bandpasses were good and stable. 

    None of these antennas returned to correct phase on the AC side, for the
2nd calibrator scan (an hour after the first calibrator).  All VLA 
antennas did. 
    On the BD side, antennas 14 and 16 returned to correct phases (an 
unlikely
coincidence, but maybe ...), while 13 was far off.   The BD problem noted at
X-band (Flukes?) was not evident at this frequency. 

    After removing the amplitude and phase mean values, the residual phases
and amplitudes were superb.  Short-term stability is excellent.  (I 
remind readers
that averaging time was 5 seconds, so short-duration drops will not be 
visible). 

    The sensitivity of antennas 13 and 14 is far and away better than 
any VLA
antenna, on all IFs.  Antenna 16 is not far behind (generally 3rd or 
4th, although
it slips to 12th place for IF C).   Curiously, the aips weights for IFs 
B and D
show 13 and 14 a factor of 2 to 2.5 higher than the median VLa antenna, 
while in IFs A and C, the factor is much more modest -- about 1.5.  No 
explanation is offered. 

    The listed Tsys values for these antennas is higher than expected 
(typically
mid 30s, although antenna 16 claims to have a Tsys of 22 in LCP, which is
hugely unlikely, given its only modest sensitivity).  However, all three 
antennas
have Tsys values far lower than the VLAs, which range from 40 to 80 K.