[evlatests] Some low-band issues

[Paul Harden]

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