[evlatests] EVLA Status, Wednesday 9 Jan

[Charles Kutz]

P-Band:
        Antenna 1 does not have the T301 installed yet. All FE cable 
repairs are complete.
         Antenna 13 is being worked on. It should not be working in any 
IF from all appearances, it has a very high level CW spike at 333MHz in 
all IFs. This problem is proving to be difficult to track down. The 
first receiver pulled for a similar behavior checked out fine on the 
bench. We took another look yesterday afternoon and are taking more 
measurements today and also taking out yet a third receiver just in case.
         Antenna 26 LCP is broke, there is a WO on it and we are trying 
to get to it.


Q-Band:
        Antenna 1 does not yet have its Q-Band installed. It is almost 
ready.


X-Band:
        Antenna 14: There is a WO open on this, FE attempted to run a 
hot/cold test last week, but bad weather prevented making any attempts. 
The Tsys calculated at the T5 agrees with stress test observations. FE 
needs to run the H/C test asap.


K-Band:
       FE will investigate.




Chuck






Rick Perley wrote:
>     Following the 2-day maint period, I checked EVLA performance with 
> the usual stress test. 
> 
>     Short Version:
> 
>     The EVLA (and VLA) are working better than I've ever seen it 
> before.  (And I hope somebody mentions that at the NRAO Town hall 
> meeting ... hint, hint, hint).
> 
>     All antennas working well at all bands except: 
> 
>                   a) antenna 1 at Q-band,  (No receiver yet, i guess)
>    
>                   b) antennas 1, 13, and 16 at P-band.  (No rcvr in 16, 
> 13 and 1 are still broken). 
> 
>                   c) VLA antenna 2 is out of the array, with a bad modem. 
> 
>                    d) The only antenna with significantly low 
> sensitivity is antenna 25 at K-band -- sensitivities low by a factor of 
> about 5 in all IFs. 
> 
>      Longer Version:
> 
>     A)  The usual bad initial record is seen on all scans, except at 
> X-band, where it follows an x-band referenced pointing. 
> 
>     B) The file was in durations, and the last scan was ended earlier 
> than it should have been -- instead of being 80 seconds long, it was 22 
> seconds long.  We lost about a minute. 
> 
>     C) The usual SSDs (short, shallow drops) were seend. 
> 
>     D) P-band (sigh):  Antenna 1 still giving essentially no fringes, 
> and is flagged.  Antenna 13 is flagged in IF#1, but not in IF2 -- but 
> should be!  Antenna 23 is unflagged in IF 2, and shows very poor data. 
>     All amplitudes were very ratty in IF 2 -- I'm pretty sure this is 
> RFI.  Other than these issues, the rest of the antennas gave acceptable 
> sensitivities. 
> 
>     E) Antenna 14 at X-band in LCP is about 20% weaker than it should 
> be.  Likely a high Tsys ...
> 
>     F) Q-Band gave excellent fringes on all antennas except #1.  This 
> despite a high (20 mph mean) wind.  Referenced pointing was successful 
> in getting the antennas more or less on source.  This was for the first 
> scan.  On the second scan, referenced pointing failed, and the antenna 
> were clearly well off the beam and moving about! 
> 
> 
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