[evlatests] Feb 14 tests and confusion

[Doug Gerrard]

	As of late yesterday, I spoke to Matt and he told my they we "close to 
having a working L302".  I can follow up today to see when it will be 
antenna ready.

Doug


Ken Sowinski wrote:
> Barry worked on evla reference pointing at the beginning and
> fought problems in the evla script he was using as well as
> problems in the system.  
> 
> When he gave up I tried to track down what was happening.
> EVLA antennas were weaker than they ought to be, but some
> EVLA to EVLA baselines showed much larger amplitudes than 
> EVLA to VLA baselines.  After a little while I saw that
> the system would occasionally snap into proper behavior
> for a few records and then go away again.  All the EVLA
> antennas did the about the same thing at the same time.
> I tried disabling phase switching for antenna 16, the worst
> offender, and it magically began to work much more solidly
> after the Modcomp skip to get phase switching turned off at
> the correlator.  From then on only 16 misbehaved at times;
> sometimes both IF pairs at the same time and sometimes not.
> When the amplitudes came and went the phases would jump; 
> sometimes the phases would jump in anticiaption of an 
> amplitude change.  In its most broken state most of the
> phase jumps were 120 degrees.  The problem certainly must 
> be in the L302(s) or its timing signals.  Do we try to do
> something about this now or what for the new L302 firmware
> and MIB software?
> 
> There is a long track of data on 3c84 at X band that the
> brave might want to find and look at.  The synoptic view
> provided by AIPS can be of more use that my limited observations.
> IAT time
> 2300   Start X band integration
> ~2330  Turn of phase switching for antenna 16.  This
>        will be obvious because 16AC data will disappear.
> 2335   Do another Modcomp skip
> 2337   Turn phase swithcing on again for antenna 16.
> 
> Once the system started working more solidly I made a survey.
> X band
> 13A has a lower response than expected and the SD voltage in
> the T5 seems abnormally large.
> 
> C band
> 16 CD looks weaker than all the others
> 13 does not work at all. No fringes, no TP, no SD.
> 
> K band
> 16 is rather weak; most likely it is not well pointed.
> 
> L band
> 13A has a lower response than expected and the SD voltage in
> the T5 seems abnormally large, just as at X band.
> 
> 
> VLA pointing was curious, but that is a story that belongs in
> a different forum.  It may only be a combination of wind and
> daytime tilt from differential solar heating.
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