[RFI] Can you identify this noise?

[K4RO Kirk Pickering]

I have a new noise in the neighborhood which appeared
about a month ago.  It caused a real problem during the 
recent ARRL Ten Meter Contest.  The noise is present from 
about 27.8 to 28.1 MHz, and it pretty well wipes out 10m CW.  

The noise seems to be there most of the time, although I 
have noticed some random periods when it is not present.
You can listen to a sound clip at the link below.  I would
appreciate any ideas on what the source might be.

http://www.k4ro.net/k4ro/audio/Noise_K4RO.mp3

Thanks,

-Kirk  K4RO