[evlatests] EVLA Health Check, Monday AM

[Jim Jackson]

Antenna 23 K and Q-bands should now be working.  There was a problem with 
the L300 which Rob has now replaced.  Someone (probably Walter) needs to 
determine the BD attenuator settings for Q-band on 23. I'm not sure if 
anyone ever did K-band either.

The P-band polarizations are being swapped on 21 this afternoon

I'm not sure what is going on with Ant 26 Q-band. Someone will look at it 
tomorrow.

With 14C and 26D, we are probably back to changing DTS modules though, 
unfortunately, they may have been put into 19 today.

Jim



At 02:14 PM 4/30/2007, Rick Perley wrote:
>     An hour of dynamic time was put to good use this morning, checking
>on EVLA viability.
>
>     The usual setup -- fast continuum, and spectral line, on a strong
>calibrator.
>
>     Referenced, and double-referenced pointing was done at C, X, K, and
>Q bands.
>
>     Results:
>
>     A) Global Observations
>
>     1) All referenced pointing scans worked beautifully.  Even the
>Q-band double-referenced pointing worked on all antenna with working
>receivers.
>
>     2) Phase stability (on the two-minute timescales I'm using) was
>outstanding, with the single exception of 14C, where the 150-degree step
>is back at P and L bands.  However, the character of this has changed,
>with a least 95% of the observations now in one phase state, and only
>occasional steps to the other state.
>
>     3) Antenna 26D has its multiple amplitude states back, visible at
>all bands.
>
>     4) All bandpasses and delays look great.
>
>     5) Antenna 13D has a 'ramp-like gain' function:  the amplitudes drop
>by ~3% over 30 seconds, then discontinuously return to the higher
>state.  Seen at all bands.
>
>     6) The usual, uncommon, short and shallow amplitude drops are present.
>
>     B) Band Specific Observations
>
>     1) P-Band:  Antennas 14, 17, and 23 working on all IFs.  Antenna 21
>has its polarizations reversed.
>
>     2) L-Band:  Antenna 13B and D (IF #2) was dead.  Antenna 24 B and D
>has a very unstable amplitude, particularly notable on D.
>
>     3) C-Band:  No fringes from 16, 21, 23 or 26.  I think all of these
>are known to be non-functional or not yet outfitted.
>
>     4) X-Band:  All 9 antennas working very well.  An peculiar gain was
>seen on 14C and D (i.e., in LCP) whereby they jumped up by 10%, then
>slowly settled back over 15 seconds to normal.  Looks like a rogue Tsys
>value.
>
>     5) K-Band:  Antenna 23 gave no fringes, but has a receiver.  Antenna
>18 was weak, and the cause is easy to determine -- a failed primary
>reference pointing because of a large (>1 arcminute) elevation error.
>Ken has convinced me that this is due to solar heating.  (Most other
>antennas showed similar offsets, but just a little bit smaller.
>
>     6)  Q-Band:  No fringes from 17, 21, 23 or 26.   The last two are
>supposed to have a receivers installed -- right?
>
>
>_______________________________________________
>evlatests mailing list
>evlatests at listmgr.cv.nrao.edu
>http://listmgr.cv.nrao.edu/mailman/listinfo/evlatests