[evlatests] 4-band fringing

[Rick Perley]

    A look at 4-band over lunch today shows:

    a) No fringes from antenna 1, 8, 24, 25, 26 or 28.
    b) Weak fringes from 2 and 14. 

    I looked only on the AC IFs, where autoleveling is working. 

    I find that Tsys/effic ~ 20,000K.   Better than I expected, given 
that this was on Cyg A, where the system temperature is perhaps 8000K 
(so efficiency may actually be close to 0.33)  .  I'll need to look at 
3C123 (off the galactic plane, and weak enough so it doesn't perturb 
Tsys itself) to get a better measure of the actual efficiency.