[evlatests] More Q-band oddities

[Michiel Brentjens]

** [2011-11-01 Tue 13:51] More Q-band oddities

The antenna 7 Q-band system showed a couple oddities over the past
weekend. First, the PDIFs of channel 7R behaved erratically, being
sometimes piece-wise constant, and showing sharp excursions at other
times. It varied by 20 - 40%. These variations were also present in
the visibilities and were fully corrected after applying the PDIFs
with AIPS task TYAPL. This smells like a problematic receiver.

During the 3C454.3 observation after sunset, the delays of IF 7C were
usually around 0.4 ns, but sometimes briefly jumped to 2.9 ns. The delay
subsequently returned to its previous value. This occurred several
times.

The delay of 23AC was 80 (A) ns and 40 (C) ns at the first scan, but
settled at a reasonable value from the second scan onwards.

- Michiel