[RFI] 160M RFI - 4 khz combs-

[HankP]

For several weeks I have been plagued with a comb of extremely stable , clean RF carriers spaced exactly 4 khz. 
At various times the comb might be only 4 or 5 carriers - at other times it will cover from about 1710 to 1910 khz . 

Day after day these carriers will be within a few cycles of the same frequencies . Typically for instance 
1811.955 , 1815.955 , 1819.955 , 1823.955. For a few days when this started appearing only three to 5 of these 
carriers would be there. Then some nights or days there would be a comb covering 1710 -1910 or so .. 

One night I returned to 160 from 40 and was happy to see no carriers at all. I preset the Alpha tune/load 
kicked it on and maybe 3 to 5 seconds of carrier for a touch up. When I stood by , the band was full 
from 1710 to 1910. - carriers at roughly -80 dBm plus minus 5 dB or so.. The first time 
this happened I was not 100 percent sure I had just not noticed the carriers had popped on before 
I fired up. (These carriers appear to stay on for a day or so after the event ) . 

This morning , I checked and the band was clear of these carriers . I keyed the K3 at about 33 watts 
a couple times and two carriers popped up 1831.950 and 1827.950 . I keyed again for maybe 2 
seconds and another carrier popped up at 1823.950 then sent Vs for about 5 seconds and another 
carrier popped up at 1835.950. As I kept this up each time another carrier or two would show up 
1839.950 etc up to 1851.950 . I just looked and now after about an hour more have appeared 
every 4 khz up to 1817.950 . Strangely the two at 43.95 and 47.95 have dropped about 8 dB 
as has 55.95 .. 

WOW - was going to pop on te ALPHA but just for hell of it sent some Vs in the middle of the 
comb - nothing changed - moved below the lost carrier sent a couple V and another carrier 
popped up. Each time I moved down another would pop up .Ahaa - if I key at freqs just above 
the comb - new carriers start popping up but I do not have to move freq -(found same was true for 
low side , carriers popped up below 1800 keying around 1810. ) 

OK after keying at 1500 watts it spreads for 1727.950 to 1891.950 . I might add that my 160 loop will null 
these sigs NE/SW and that is NOT pointed at my house. I have probed all around the house - turned router 
off . DirecV etc etc . That same heading also drops a broadband noise 10 dB at that heading . 


I built a ferrite rod antenna that tunes 160 so will see if I can snoop outside some .today with my R10 rx. . 

Hank K7HP 

What am I looking for ?