[Lowfer] Noise I've never heard - Anyone recognize it

[Andy - KU4XR]

https://dl.dropboxusercontent.com/u/49203948/Noise%20at%20KU4XR%202-10-2014.mp3

I have not heard this noise before today.. In A.M. mode - 6 KHz BW with NB, it's 8-1/2 S-units..
without the NB, it is 15 over S-9 .. Without the NB, the pulsing noise is everywhere on LF, and on
any antenna.. With the NB, It starts at 127 KHz, Peaks at 135.5 KHz, and stops at 144 KHz..
The mp3 is 40 seconds.. The first 20 seconds is with the NB ON, and the last 20 seconds is
with the NB OFF .. Regardless of the mode used; it is impossible to hear anything thru this noise..
Nothing has changed in the house.. It may be no relevance at all, but on Sun. morning on the way 
to work, I saw a power crew working on one of the High Tension towers about 3/4 miles from me..
They had the dirt around all the base pylons dug out, and I have no idea what they were working on..
It could be purely coincidental, but the timing surely raises suspicion.. I had my A.M radio on in the
van earlier today as I drove under that tower, and I didn't hear any strange noise on the BCB, but
the radio went totally dead while under the wires.. 

73 to all, and I hope I will be able to hear again someday soon...

Andy - KU4XR