[evlatests] K-Band results

[Rick Perley]

    continuing the narrative, for K-band ...

    A) In fast continuum:

       no amplitude drops, and no phase spins.

    Antenna 14 amplitude and phase gain behavior essentially 
indistinguishable from neighboring VLA antenna
    Antenna 16A has the ubiquitous 'square wave' amplitude gain.  
Otherwise, antenna 16 gain behavior is essentially indistinguishable 
from the neighboring VLA antenna. 

    Antenna 14 and 16 back-end Tsys values are right where we expect 
them:  45K for 14, 55K for 16. 
VLA antennas show much higher Tsys values:  65 to 100 K.  But (so far as 
I understand it), they should
be the same -- they have the same receivers and feeds.  Hence, as the 
Tcals for 14 and 16 have been
updated (right?), I wonder if the Tcals for the VLA antennas are 
significantly in error.

    Sensitivity of 14 and 16, as judged by rms noise on cold sky after 
calibration on 3C84, is perhaps
10 - 20% worse for 14 than the best VLA antennas, and 20 - 30% worse for 
16, than the best VLA antennas. 

    Note:  This small degradation appears to be the same for all bands 
(except C-band, although I might
be able to convince myself that the degradation is offset by the 
improved system temperature). 

    B) In line mode:

    An unmistakable phase spin, of 11 degrees/second, was seen on 
antennas 14A and C *only*. 
14B and D, and all four IFs for antenna 16, behaved normally. 

    The 10-second amplitude drops were seen on all four IFs, with about 
6% amplitude drop on
alternate 5-second averaging.  (I used a slower integration time than I 
could have).