[evlatests] status, Aug 3 2006; what happened to antnna 13?

[Rob Long]

Ant 13 was out of sync this morning.  Jim re-sync'd the antenna and 
reset the DTS modules.

Rob

Ken Sowinski wrote:
> Not much was achieved today.  L band focus tests were reported
> elsewhere.  The 13C DTS module was replace and works.  Both L301s
> are now working in antenna 16.
> 
> The poor performance Michael reported for many antennas was
> verified.  Observations were made to measure the correlation
> coefficeint as well as observations with the T_sys correction
> applied to distinguish T_sys problems from other problems.
> The most striking problem is that antenna 13 is very bad at
> all bands.
> 
> X band
> 13 and 18 are really bad; about 1/3 expected power.  18 looked
> more reasonable with the T_sys correction applied suggestion
> that T_sys is too high.  Moisture?
> 
> C band
> 13 is really bad.  16CD is weak; about 1/2 expected.
> 
> L band
> 13 is really, really bad; about 1/4 or less of what is expected.
> 14 is not good; about 2/3 of expected power.
> 18 is OK, but the L302-1 consistently fails to lock at the
> standard L band setup.
> 
> K band
> 13 and 18 are really bad; about 1/3 of the expected power.
> 
> Q band
> 13 was bad, but pointing was not checked so that may be part
> of the problem.
> 
> 
> The problem with antenna 13 does not seem to have any of the
> usual explanations.  The bandpasses look OK at X band.  There
> are no delay errors.  The degradation does not scale with
> frequency so it is unlikely to be pointing or a poor LO.
> About the only thing left is extra noise getting in at or after
> the downconverter.
> 
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