[evlatests] ea20 gain variations

[Rick Perley]

     Rob:

     Ken wonders about pointing.  If so, this would affect X-band more 
than C-band.  The variations are 10% (in power) for both runs. However, 
the frequency difference was not large -- 7.0 GHz center for one, 9.0 
GHz for the other.
     I have Ku-band data, but not analyzed yet.  (Drowning in data here ...

     Rick

On 01/19/2016 03:10 PM, Rob Selina wrote:
> Hi Rick,
>
> No obvious issues with HVAC, plots attached for Sunday.
>
> Mapping of monitor points courtesy of Jerry Langevin:
>
> P301-1-EXT2 > Vertex Room Ambient
> P301-1-EXT1 > LO/IF Rack, between door and modules.
> P301-2-EXT1 > LO/IF Rack, Input plenum
> P301-2-EXT2 > LO/IF Rack, Exhaust plenum
> P302-1-EXT1 > Utility Rack, above D301
> P302-1-EXT2 > Utility Rack, above D303
>
> Any other suggestions to look into?
>
> Cheers,
> Rob
>
>
> -----Original Message-----
> From: evlatests [mailto:evlatests-bounces at listmgr.nrao.edu] On Behalf Of Rick Perley
> Sent: Tuesday, January 19, 2016 2:10 PM
> To: evlatests at aoc.nrao.edu
> Subject: [evlatests] ea20 gain variations
>
>       I noted last week how the switched power system nicely corrects gain changes at X-band.
>
>       In another 'beam holography' run, taken Sunday evening at 6cm, the same type of gain variations noted earlier in ea20 at X-band are present in that antenna at C-band.  I attach a plot of the 'PDif' values.  The gain variations are significant -- about 10% in power. The timescale is about 1 hour.
>
>       I would guess that something is quite amiss with the temperature control, since this behavior is seen on (at least) two different bands.
>
>