[evlatests] P-band status

[Paul Harden]

On 1/15/2014 3:52 PM, Rick Perley wrote:
>      2) Weak/dead polarizations:
>                  ea06R  (down by a factor of 15 in power)
>                  ea25L  (down by a factor of over 400)
>                  ea13L  (down by a factor of a few, and also highly
> variable in gain)
>                  ea04L  (down by a factor of about 2).

Some of these receivers have been checked for proper output power.  Some 
of these power problems *may* be in the LO/IF system.  Will start 
checking if receiver or downstream problem.

>      3) Unsteady or bizarre behavior:
>                  ea13L  (as noted above)
>                  ea19L  highly variable -- hard to summarize.

Will replace those two receivers fairly quickly to diagnose and repair. 
  Unsteady and bizarre receivers have our highest priority!

>      4) Switched power status:
>
>                  Nearly all antennas give PDif values between 0.1 and 0.6
> counts.  Exceptions are:

Will check the noted antennas for proper CAL switching and CAL power. 
Two of those antennas are known outstanding problems.

>      5) Polarization status:
>
>                Much improved!  All the really high polarization antennas
> are much better.

Thanks.  The antennas reported previously with high cross polarization 
were found to have dipoles misaligned by 15-20 degrees.  All fixed.

>                The list of high polarization antennas is now:  (all have
> X-pol between 10 and 25%, mostly at the low end):      ea11 (the worst
> at 25%), ea04, ea15, ea20, ea26 and ea28.

We'll check for dipole misalignment on the above and correct if needed. 
  This requires a physical realignment of the dipoles from inside the 
apex barrel.

EA15 - We realigned this dipole Wednesday while we swapped receivers. 
It was somewhere around 5-10 degrees off.  It was fixed, apparently, 
shortly after your test run.  EA15 hould be OK now.  We'll check the others.

Thanks for the fresh update on the low band.  It is good to see most of 
the antennas with previously reported problems now working well, and 
we'll continue to tackle the existing problems.

On some of these, we have gone as far as we can with spectrum analyzers 
and test equipment.  Your feedback is always valuable to address the 
problems we can't really see (like weak CALs).  Thanks.

Paul