[evlatests] EVLA System Check, 29 march

[Jim Jackson]

Antenna 21 is clearly not working at all.  I even tried power cycling the 
entire LO/IF rack using the new ON/OFF command in the P301's.  After 
resyncing everything, it came back to the exact same same state - IF's A & 
C are completely dead and IF's B&D show no switched power on X or K 
-band.  Jerry and I are going out to look at it tomorrow (and taking some 
of Antenna 19's modules in case we need them).

We are also hoping to install the T301 4P converter in 21 at the same time.

If  antenna 14 is available, I'll also try to look at that strange behavior 
in 14C at P and L bands.

Jim

At 12:01 PM 3/29/2007, Rick Perley wrote:
>     I used 30 minutes at the end of Dynamic Time this morning to check
>out what's working, and what isn't.
>
>     I did the usual things:
>
>     1) Fast continuum dumps (0.42 seconds) at L, C, X, and K bands to
>check for stability behavior,   (I didn't do Q, for lack of time, and
>out of general distrust of pointing.  A mistake.  See below).
>     2) Spectral line, mode '4', to check bandpasses and sensitivity, and
>P, L, C, X bands.  (I forgot to add K in, in my rush to beat the ticking
>clock).
>
>     Primary referenced pointing was done at C, X and K bands.  Winds
>were light.
>
>     Results:
>
>     General Results:
>
>     1) Referenced pointing worked!  So it appears that either:
>              somebody fixed the flagging problems overnight, or
>               the flagging of EVLA antennas (other than #14) which
>caused pointing tests to fail the last two days, is triggered by wind.
>(A hair-trigger, I would venture to say).
>
>     2) Other than oddities at the beginning of the L-band continuum
>observation, the performance of the EVLA antennas is very good indeed.
>
>     3) No phase drifts were noted at any band -- however, the scans were
>less than 2 minutes long, so the limits on temporal phase slopes are not
>small.
>
>
>     Specific Results, organized by band.
>
>     1) P-Band.
>
>     As already widely known, antennas 14, 17 and 23 are outfitted at
>P-band.
>
>     14 A and C gave no fringes.  14 B and D were find.  Antennas 17 and
>23 were good on all IFs.
>
>     2) L-Band.
>
>     I elected to observe simultaneous a new pair of frequencies -- 1465
>and 1835 MHz, now that we have a pair of VLA antennas that work at that
>upper frequency.
>
>     The first minute of the continuum (fast-dumped) data showed bizarre
>amplitudes and phases on nearly all antennas (both VLA and EVLA).  As
>this behavior did not show up on any other scan at any other frequency,
>I'm going to ignore it for now.
>
>     The phase of 14C is oscillating back and forth by 150 degrees, on
>timescales of a few seconds.  This behavior was also seen yesterday at P
>and L bands *only*.   The oscillation is absent today also at C, X, and
>K bands.
>
>     Antenna 21 has no receiver.
>     Antenna 24 gave no data on any IF.
>     All other EVLA antennas worked fine.  Sensitivities are all within
>normal bounds, at both frequencies.
>
>     3) C-Band
>
>     Antennas 21 and 23 have no C-band receivers.
>
>     Antennas 26 and 24 gave no data (and did not return pointing
>solutions either).
>
>     The remaining 5 antennas (13, 14, 16, 17, 18) all worked well.
>     Antenna 17 showed occasional (1 in 100) small dropouts in
>amplitude.  No phase effect noted.
>     Sensitivities for 14, 16, and 18 are the best in the array.
>Antennas 13 and 17 are like VLA antennas.
>     Tsys for 13 and 17 are too high -- particularly 17, which has Tsys
>between 65 and 110 (depending on IF).   Antenna 13 Tsys is about 60,
>explaining why its sensitivity is like the VLA norm.
>
>     4)  X-Band.
>
>     All 9 EVLA antennas are outfitted at X-band.
>     Antenna 21 gave no sensible fringes.  21A and C are truly dead, B
>and D are sort-of alive (but not useful).
>     Antenna 24 gave a pointing solution, but no continuum data.  It
>returned for the line data.  I have no idea why it was missing for one
>of these three scans.
>
>     Otherwise, all others are just fine.
>
>     Antenna 26 A and C have occasional amplitude drops (about 1% of the
>data), lasting a single 0.416 second integration.  The two IFs drop in
>synchronism.
>
>     Sensitivies of 13, 14, 16 and 26 are excellent -- better than all
>VLA antennas.
>     Sensitivities of 17 (all IFs) and 14C and D are poor.  These
>antennas have high Tsys.
>
>     5) K-Band.
>
>     Eight EVLA antennas are outfitted at K-band, and they all work just
>fine!!!
>
>     Antenna 26 has occasional drops, identical to those noted above for
>C and X bands.
>
>     Sensitivies of 14, 16, 23, and 26 are all excellent.  Antennas 13,
>17 and 18 are all about the same as average VLA.
>     Only 24 has poor sensitivity -- clearly due to the reported high
>Tsys of over 100 K.
>
>
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