[evlatests] L-band Status

[Rick Perley]

    Due to the quantity of data, I'll report on each band separately. 

    L-band data were taken at 1485 MHz (AC) and 1275 MHz (BD). 

    Antennas 13, 14, 16, and 18 gave good fringes on all IFs.

    Antenna 24 gave fringes only in RCP (IFs A and B).  The data from 
LCP were nonsensical, as were the Tsys values.  Something in the 
communications? 

    Stability looked fine -- but there were only a few minutes of data, 
with no changes in frequency. 

    Sensitivity was surprisingly good!  Below is a table of the *rank* 
of the antenna-IF, amongst all antennas.  A low number means very good, 
a high number is very bad.   Remember that IFs A and C are at 1485, IFs 
B and D at 1275. 

Ant/IF   A      B      C      D
-----------------------------------
13         22     4      18      2
14        19      3      20      3
16          8      6      13     14
18         4       2        6       1
24         1       1       X      X
26         not outfitted yet
------------------------------------

          Note that antennas 24 and 18 ('new') are the best, or near the 
best, in the array at both frequencies.   Also note that the trend noted 
earlier (lower frequencies are good, high frequencies not so good) 
remains for all antennas.  There is a clear trend that the higher 
numbered EVLA antennas (the newer ones) are better than the 'old' ones, 
especially at the 1485 Mhz frequency.  (So, whatever we're doing, we're 
heading in the right direction!). 
       Although the trends are good, I'd still like to know the reason 
for the poor sensitivity of the earlier antennas at higher L-band 
frequencies. 
       People interested in red-shifted HI will be pleased indeed at the 
performance!  (And they probably won't care that we can't explain why! :) )