[evlatests] Pdiff compression, hardware update

[Keith Morris]

On Monday, Rick conducted another pdiff compression test, this time 
observing Taurus A at 5 different receiver bands -- L, S, C, X, and Ku. 
  Nothing* in these tests suggests a clear correspondence between the 
most compressed antennas and any particular receiver band; the most 
compressing antennas seem to be randomly distributed across receiver 
bands.  For example, at L-band, ea23 is the 7th most compressed antenna, 
while ea23 is the most linear antenna at C-band.

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*The one possible exception is ea25, which showed rather bad compression 
at L, S, and C bands.  This could be a coincidence, or it could be due 
to unleveled receiver outputs coupled with a misbehaving T302.  We will 
swap the T302 tomorrow.
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At the most recent pdiff compression meeting, it was suggested that we 
should identify two or more antennas to modify next.  We will visit 
ea18, ea21, and ea25 tomorrow, and set receiver output levels at the 5 
bands that Rick tested in the Taurus A script.  Rick -- can you re-run 
the test after we do this?

-- 
Keith Morris
National Radio Astronomy Observatory
1003 Lopezville Rd.
Socorro, NM 87801
575-835-7060 (phone)
575-835-7027 (fax)