On Tue, 24 Mar 2009 14:42:02 -0700 (PDT), WILLIS COOKE wrote: >From that I would suspect that it originates in my computer or >possibly router.
Ethernet terminals (computers, routers, switches, hubs) are well known to generate interfering carriers on 30M, 20M, 15M, 10M, and 6M. The clocks are local to each system, so if you have neighbors, it's common to hear a cluster of them around 14,029, 21,052, and the low end of both 10M CW and 6M. Most, but not all, of the signal is radiated common mode by the Ethernet cable. Some of it is also radiated by wiring internal to the Ethernet terminal due to lousy shielding. The common mode part (nearly always a lot stronger than the internal wiring) can be attenuated a LOT by winding 4-7 turns of the Ethernet cable around a 2.4-inch toroid of Fair-Rite #43 or # 31 material. For long cables (more than about 1/4 wavelength), you will need a choke at each end of the cable. Each cable attached to the Ethernet hardware is capable of radiating the signal, so it may need a choke. Linksys products are well known to produce a lot of this trash. If you hear more than one of these carriers, kill power to your Ethernet router, switch, or hub to see which of those carriers goes away. That's the only one that you'll be able to choke (unless you are on really good terms with your neighbors). Now, restore power to it and apply the chokes while you listen to the strength of that carrier. More info on this in http://audiosystemsgroup.com/RFI-Ham.pdf 73, Jim Brown K9YC ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[email protected] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
