[evlatests] new Ka band receivers

[Ken Sowinski]

ea06 and ea23 had Ka band receivers installed over the last few days.
Both work and have had the usual parameters set.

ea23 is about as good as the other Ka band receivers; ea06 is poorer
by about one-third.  It is not possible to set the T304 attenuators
to get the power levels we desire.  the 4 GHz input attenuator must
be set high to get the -20 dBm we expect, and then there is not enough
gain to deliver the -30 dBm expected in the 1 GHz output band.  I
deduce that there is extra out of band (the 1 GHz output band) noise
that is confusing the downconverter.