[evlatests] Two L-band issues

[Rick Perley]

    I'm finally getting around to looking at L-band data, taken last 
August 25. 

    Two issues stand out:

    1) There is zero-mean PDif on ea18.  Mostly likely the noise diode 
is not switching.

    2) The cross-polarization on ea19 is *huge* -- about 50%.   The 
system temperature is also very high -- 50 to 100 K.