[evlatests] 36 GHz 'RFI'

[Chuck Kutz]

We could easily unplug  the x-band receiver and see if the birdie goes away.
Would Monday be soon enough?

 

Chuck

 

From: evlatests-bounces at nrao.edu [mailto:evlatests-bounces at nrao.edu] On
Behalf Of Emmanuel Momjian
Sent: Thursday, February 10, 2011 5:48 PM
To: Rick Perley; evlatests at aoc.nrao.edu
Subject: Re: [evlatests] 36 GHz 'RFI'

 

Perhaps it is worth noting that antenna 10 had a couple of internal birdies
at Ka-band, and one of them was at 36286 MHz (very close to the frequency
that Rick has reported for antenna 22's birdie). See
http://science.nrao.edu/evla/observing/RFI/Ka-Band.shtml

The problem on antenna 10 was fixed early October 2010, and I believe the
cause was a faulty X-band LNA (Dan and Chuck may elaborate on the details).
I am reporting this just in case the problem seen on ea22 has a similar
origin to what ea10 had some months ago.

em



On Thu, Feb 10, 2011 at 5:32 PM, Rick Perley <rperley at nrao.edu> wrote:

   I got some time to look more closely at the 36280 MHz 'birdie'
reported on yesterday.

   It is only on antenna 22, in both RCP and LCP, but stronger in the
former.  It is seen on all baselines between 22 and other antennas, but
on no other baselines -- even those comprising adjacent antennas.  The
strength of the 'line' is much stronger on short baselines to 22 --
indicating that fringe winding is operating.

   So this would presumably be an internal signal.


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