Hi Hank, The case I'm currently working on sounds very similar to yours but at 8 Khz separation and it's due to an AC servo drive on an injection molding machine 0.5 miles away (a visiting ham in my shack said the signal just sounded like someone tuning up his rig as it's a pretty clean and narrow signal). 4 khz and 8 khz are very common carrier frequencies in the world of variable speed drives (case earlier this year that I worked on used a 4 khz carrier). In my current case I notice slightly lower signal levels on the even harmonics, and the signals appear from below 160 meters all the way through 160 meters and slightly beyond.
Generally I try not to guess at the source as that sometimes puts blinders on when tracking down the culprit. The only time I really try and figure out what the source might be is when it's broadband white noise, and then I try and determine if the interference is power line arcing related versus some other kind of source (pretty easy to do). If it looks like power line arcing then I use a AM VHF radio with directional antenna for direction finding as I approach the source versus an HF rig with directional antenna. 73, Don (wd8dsb) On Tue, Dec 15, 2015 at 1:31 PM, HankP <[email protected]> wrote: > > 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 > > > > > > > _________________ > Topband Reflector Archives - http://www.contesting.com/_topband > _________________ Topband Reflector Archives - http://www.contesting.com/_topband
