Topband: Noise levels on 160

[HankP]

Since the subject of "un-intentional radiators " has come up , I had one
appear about a week ago .  5 very clean very stable -80dBm  carriers
4 khz apart starting at 1815.957, 1819.957, 1823.957, 1827.957 ,1831.954 .

Then Sunday evening  at 0446 I moved my amp back to 160 and when I sent
 my call , looked at the P3 panadapter and there was a comb
from at least 1710 to 1910 every 4 khz. I cannot swear it changed from
5 carriers to a comb when  I popped 1500 watts out - but it is now on
24 hours a day.  

It nulls NE/SW so is possibly from a new neighbor who seems to be running 
a business about 250 feet away from my loop to SW - and I suspect some
sort of router.

Today I will wind up a ferrite rod loopstick for my R10 rx and go sleuthing
I cannot detect it anywhere except the 1710 to 1910 range - nil on 80 and above.
There may be some weaker stuff below 1710 but hard to tell . 

Any gurus out there have an idea ? 

Thanks

 Hank K7HP