[evlatests] P-Band, this day

[Rick Perley]

    A short observation this morning reveals some significant issues 
with P-band, some of which are so gross that I hope the problems can be 
identified relatively quickly:

    1) Antennas 4, 13, 16 and 25 give no fringes -- and none of them 
should! 

    2) VLA antenna 8, on all IFs, is showing two different gain states, 
differing by a factor of about 5 in amplitude.  The pattern of up and 
down are different on all IFs.  The recorded system temperatures are 
highly variable, ranging from a relatively normal value  of ~150K to 
values of up to 100,000 K (!) on all IFs.  Pretty gross! 

    3) EVLA antenna 21 also shows two different states on all IFs, and 
also has Tsys values varying over a range of ~100 K to over 150,000 K.  
Something seriously broken here. 

    4)  EVLA antenna 23 is very unstable in IF 'A' only, and has 
similarly unstable Tsys values -- varying from a few thousand to 100,000 
K.  All other IFs look normal. 

       5) EVLA antenna 20, IF 'A' only, has a Tsys two times too high, 
and a statistical weight low by a factor of four -- clearly due to the 
Tsys. 

        6) EVLA antenna 26 has system temperatures typically about 
1000K, and has very low amplitude (and very, very low weights) on the BD 
side. 

        7) EVLA antenna 24 has system temperature a factor two to four 
too high, and an amplitude -- only the A side only -- a factor of 3 too 
low.  The Tsys for that IF shows a sinusoidal variation of period 15 
seconds, range of (only!) 3 K, and a mean of 535 K.  These values are 
not reasonable. 

         8)  EVLA antenna 11 has Tsys of 1000K on IFs A and C (but 
reasonable values on B and D).  Gain solutions appear fairly normal, but 
the statistical weights indicate the antenna's sensitivity is low by a 
factor of 5 to 10 on all IFs.