[evlatests] ea13 is radiating at L-band!

[Terry Cotter]

The VOIP box is contained inside a shielded "rack". There are low pass 
filters that are used for the voice pair that goes to the analog phones 
in each antenna. Since ant 13 was the first antenna something might be 
amiss with the filtering, turning the phone pair into an antenna. We 
will check this out.

Vivek Dhawan wrote:
> 
> VOIP phones were found to be quite noisy, with a 25 MHz comb. Is the phone
> off the hook at ea13? or is the converter box (not sure of the correct term)
> doing some radiating?
> 
> http://www.aoc.nrao.edu/evla/geninfo/memoseries/evlamemo99.ps
> 
> On Sun, January 20, 2013 11:51, Rick Perley wrote:
> |     The latest 'spectra sweep' shows clear evidence that ea13 is
> | seriously polluting our spectrum at L-band.  In trolling through the
> | spectra provided from the data, some baselines common to ea13 show
> | strong RFI at multiples of 25 MHz, extending from ~1200 MHz through
> | ~1500 MHz.  There are only a few baselines on which this comb is easily
> | visible -- these are 13 with 9, 14, 24, 25, and 26.  All of these are
> | antennas adjacent to 13!
> |     It's quite clear from this that ea13 is probably the sole source of
> | the interference.
> |
> |
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> 
> 
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