[RFI] Finding noise source

[Yuri]

For a couple of years now, I am suffering from terrible noise at my place 
which covers pretty much all HF bands when it's on.
You may listen to it here: http://www.rigexpert.net/noise.wav
The noise seems like a power line one, and it stays on for days, but 
sometimes (very seldom though) when I listen to the bands in the morning 
before going to work, the noise is not there, which makes me think that this 
might not be the power line noise.
I can easily determine the direction where it's peaking from - my 
neighbour's house, but this is also a direction to the street power lines.
Since I only have one tower with rotatable beam (TH6DXX), I decided to built 
4 element 2 m yagi and try to determine the bearing from outside of my front 
yard, using IC746 radio on 2 meters. But, either the sensitivity of the 
receiver on 2 meters is not enough, or the noise itself is not strong on 2 
meters, I can not tell by looking on S-meter, where the noise is coming 
from - S-meter stays on "0" all the time though the noise is still audible.
The question is, what would you recommend me to use as a "noise finding" 
device? I don't really have enough time to build something complicated. I 
have to find out either it's power line noise, or the one coming from my 
neighbour's.
Thanks in advance for the tips.

Regards,

Yuri  VE3DZ