[evlatests] ea02 summary

[Dan Mertely]

Is the L & C problem equally bad on all 4 IFs?  -Mert

Ken Sowinski wrote:
> Collimations have now been set for all bands, including Q band.
> Performance is about what we expect at X and K bands and, maybe,
> Q band as well.  However all is not well at L and C bands.
> 
> C band is clearly worse than all the other EVLA antennas, and
> some VLA antennas.  At L band the fringe amplitude against a
> good antenna is about half what we expect; about one-fourth
> in power.  I have looked for culprits and have found none.
> since the problem is much worse at L band I have looked for
> causes there.  It is not optics or T_sys because the deflection
> in total power going on and off 3C273 is the same as another
> EVLA antenna.  Delay errors are of order a ns.  That only leaves
> an LO coherency problem, but it is hard to see why L band is
> affected more than C band; and why K and Q bands are unaffected.
> Crossed hand power in L band is a small fraction of parallel
> hand power so we do not have an OMT problem.
> 
> Any ideas?
> 
> 
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