[evlatests] Antenna 27B

[Rick Perley]

    Although others have noted this, and some others have seen the 
evidence, I thought it useful to broadcast the following to a larger 
audience:

    Recent data (since last night, at least) show that antenna 27, IF 
'B', is making large and abrupt changes in its gain.  The changes are 
large -- in my 6cm data from last night, there were two changes, each of 
3dB.  The effect is seen in the power sum, power difference, and fringe 
power.  Tsys is only slightly affected.  There is no significant phase 
effect.  The bandpass shape clearly changes.   All this points to the 
T304 attenuator changing.