[evlatests] Some low-band issues

[Rick Perley]

    Paul:

    Thanks for the reply.

    So, it seems that  ea01 and ea03 should show fringes, but don't.  
(In fact, ea01 was fringing, but the SNR was so low I had to leave it 
out when making a bandpass calibration). 

    Perhaps Ken or Barry can update the parameters database with the Cal 
values. 

    As for the F14s -- we'll try find out how to make sure these are on, 
when needed.

    Rick

   
   

Paul Harden wrote:
>
>
> Rick Perley wrote:
>  >     1) No astronomical signals came from ea03, ea08, ea26 or ea27 
> -- all
>> of which are claimed (on the Coordination Meeting Summary) to have 
>> low-band receivers. 
>
> The antennas WITHOUT low band receivers since 1 MAR are:
> 07, 08, 10, 12, 14, 16, 21 and 27
>
> Low band receivers (LBR) will be installed in EA07 and 14 next week.
> EA15 and 19 have known cable problems which should be repaired shortly.
>
> A map showing which antennas have and have not LBR receivers is at:
> http://www.aoc.nrao.edu/~pharden/LBR/lbr.htm
> I update this web page upon every low band installation.
>
>>     2) Zero-mean PDif values (or values so small they are not 
>> meaningful) were found in ea01, ea04, ea11, ea13, and ea25.   For all 
>> these, the PSum values look normal, so it appears the noise diode is 
>> not switching. 
>
> No CAL switching is a continual complaint.  I have been to every LBR 
> antenna with a spectrum analyzer, where I can clearly see the CAL 
> switching on 74MHz, even without the dipoles.  TCAL on P-band is too 
> small to see.  The LBR gets the CAL switching signal from the old F14s 
> driving the old card cages.  In many cases upon entering the Vertex 
> Room, CAL switching on the F14s is turned off.  I don't know why they 
> are getting turned off.  Regardless, on a low-band run, have the VLA 
> operator issue the command that turns on the CAL switching to the 
> F14s.   It doesn't seem to be in whatever script you use.  Trust me - 
> it works when the CAL/SOLAR CAL command is sent to the F14s.
>
>>     3) Clearly incorrect system temperature values (typically, 10K) 
>> were derived on ea13, ea22, ea23, ea24, and ea28.  The reason is 
>> simple:  These antennas have not had their Tcal values entered into 
>> the database.  (For these, and for ea01, ea04, ea05 and ea25 the 
>> value is 1.0 -- the default. )
>
> On the above linked web page, there is a table showing all EVLA 
> antennas and those with receivers installed.  The Tcal values for both 
> 4- and P-bands on each installed receiver are also shown on that 
> table.  I can provide Trx and other hot/cold test data if you need.
>
> Paul Harden