The "QRM" on 14.316 is unlikely to go away, ever. This is the 4th harmonic of 3.579 MHz, the TV color burst frequency, and a popular choice for oscillators in all sorts of consumer and office devices (not necessarily TV receivers). This has been a problem on 20 meters for at least 30 years that I know of, perhaps longer. Also, because many devices that use this frequency derive it from a square-wave oscillator (a couple of gates). the harmonics of these devices are often prodigious. Another considerations is that because some designs need to have this frequency only approximately correct, it is no surprise to find some units running up to a few hundred Hertz plus or minus from 3.579, and thus (after multiplication by harmonics) hams end up with a broad band of QRM that can be 2 or 3 kHz from 14.316, or anywhere in between.
Are all these sources "illegal", and thus covered by part 15 rules? Yes, they are. This is part of what manufacturers "certify" on those Part 15 labels you see on so many items of consumer electronics. Technically, the owner of the device is at fault, and could be made to cease and desist using the offending item. However, then we have the real world. Identifying, finding and fixing what could be several dozen such sources in your immediate vicinity can be and for practical purposes is an unsurmountable problem. The FCC literally cannot help you here, as much as they might want to. They have neither the budget or time to solve literally tens or even hundreds of millions (no exaggeration here!) of these cases. Pandora is well and truly out of the box on this one. I would respectfully suggest a permanent change of net frequency to something less likely to have this problem. - Jim, KL7CC Phil and Christina wrote: > We kept our frequency on 14.314 MHz again today to try to dodge some QRM > that has been persistent on 14.316 for some people. ______________________________________________________________ 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
