[evlatests] new receivers

[Ken Sowinski]

There was a report of receivers installed today.

ea12 K band works fine and pointing is likely good enough for astronomy.

ea12 L band works, but the polarizations are swapped.

ea17 Ka band doesn't work at all.  There is power in the downconverters
      from somewhere, but no hint of a fringe.  No switched power from
      the receiver.  Perhaps something is hooked up wrong, or the feed
      cover is still in place.