[evlatests] Addendum to 16D amplitude oddities

[Rick Perley]

    A couple of added notes:

    1) At L-band, the change in amplitude occurred between the first two 
scans -- which were observed consecutively.  That is, there was not a 
change of band between these two observations.  (The first was the 
'dummy' scan, to allow the antennas to get on source).  Note that no 
other IF at this band saw any change in amplitude between these first 
two scans.

    2) At Ka-band, where no change in amplitude was found (the only band 
this occurred at), the frequencies were 33.43 and 33.56 GHz -- which 
doesn't use the converted path.