If it's not found to be a TV monitor with an approximate 40 kHz horizontal sweep rate, then the next most likely will be a switching power supply that runs at 40 kHz, rich in harmonics. I'd look for LED lighting that comes on in the evening, like under-cabinet kitchen lighting, or low-voltage yard lights. I had a couple of light sensor sockets in my front and back porch lights that were radiating when the lights came on automatically in the evening. Also found an automatic coffee maker making a racket, and a switching power supply in a laser printer.
You may be able to isolate it to something in your house by turning off circuit breakers in your electrical panel one at a time (or if you like to split the dictionary faster, do one-half at a time, and then cut that in half again, and again). Once you know the circuit, then you can start unplugging or turning things off or on. Having a handheld radio that picks up the noise will be helpful. Hope that helps, -- Dave, N8SBE > -------- Original Message -------- > Subject: [Elecraft] P3 Noise signature > From: Fred Jensen <k6...@foothill.net> > Date: Mon, April 29, 2013 10:17 pm > To: Elecraft Reflector <elecraft@mailman.qth.net> > > > I usually check into the No Cal Net on 3533 each night. I've begun to > get predictable noise with a unique signature on the P3 WF. It's a > series of bands, the first [around 3545] is the widest, they get > narrower up from that and the separation seems to be about 40 KHz. The > higher components get narrower but aren't any weaker. > > Occasionally I've see it come on to an otherwise quiet band, and all the > "bands" on the WF drift some before stabilizing. > > I have a screen shot from the P3 I'll send, anyone have any idea what > this is? I never see it in the daytime on any band, just in the > evening, which is suspicious ... plasma TV? > > If it's my neighbor Casey, I'll just need to live with it, we don't do > battle with our neighbors. Besides, Sampson, their cat, gets along with > ours and shares his food. > > 73, > > Fred K6DGW > - Northern California Contest Club > - CU in the 2013 Cal QSO Party 5-6 Oct 2013 > - www.cqp.org > > ______________________________________________________________ > Elecraft mailing list > Home: http://mailman.qth.net/mailman/listinfo/elecraft > Help: http://mailman.qth.net/mmfaq.htm > Post: mailto:Elecraft@mailman.qth.net > > This list hosted by: http://www.qsl.net > Please help support this email list: http://www.qsl.net/donate.html ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
