[evlatests] Switch STability tests, cont.

[Ken Sowinski]

On Mon, 1 Aug 2011, Rick Perley wrote:

>    1) Ku-band is unique in its poor amplitude stability (defined here
> as scan to scan, not within any one scan).  In all cases, all four IFs
> change in similar ways -- this looks like pointing, but this conclusions
> is not supported by review of the higher frequency stability.  This
> could be pointing nonetheless, *if* the collimation values are very
> poor.   For some antennas, the variation in one polarization is similar,
> but larger than, that in the other.  This can also be due to pointing,
> so long as the collimation values are poorly determined.

There was a very short collimation pointing run late last week
using only the antennas with Ku band receivers to determine the
collimation offsets for the new Ku band receiverin ea21.  I only
examined the result for ea21 at that time.

I have now looked at all the antennas paying particular attention
to the Ku band offsets.  Below I list the worst offenders, including
the errors in arc-minutes when significant.  A comparison of this
list with the antennas having poor stabilty at Ku band would be
interesting.

5  Out of service
6  OK
7  OK
10 OK
12 OK
13 OK
14 Ku  (0.14, -0.28)
16 Ku  (-0.16, -0.40)
18 Ku  (-0.64, 0.38)   all bands were bad for this antenna!
20 Ku  (-0.13, -0.27)
21 Ku  (-0.31, -0.28)  this was fixed on Friday
22 OK
23 Out of service
24 OK
26 OK