Oh good grief. 3.579 (approx) MHz is the color burst frequency, and pretty much any standard NTSC color TV set (vacuum tube or solid state) has a crystal oscillator that runs on that frequency. The _horizontal_ sweep oscillator is on about 15 kHz, and the _vertical_ sweep oscillator runs at slightly less than 60 Hz. This same 3.579 MHz oscillator is the reason for the persistent weak signal on 14.312 or 14.313 (the 4th harmonic of 3.579) that plagues many of us.
Also, many devices use this same 3.579 (more or less) frequency to control some internal function or process - crystal controlled clocks, fax machines, microwave oven timers, and video games being only few examples. TV sets are locked to a particular frequency by the transmission they receive, whereas other devices are not. This is the reason you can often hear many many individual signals around these frequencies - particularly on 20 meters. I am not too sure about more modern HDTV receivers. Hopefully they use a different mechanism,. so perhaps we will see a gradual lessening of this problem as time passes. Or not. - Jim, KL7CC Monty Shultes wrote: > 3580 is a magic frequency, actually 3979.xx is the vertical (horizontal?) > oscillator frequency in OLD tube TV sets. I've been listening to that buzz > for decades. > Best Holiday Wishes to all - Monty K2DLJ > > O That said, I'm > >> seeing some noise on 80m that is always present at night, on 3580 khz >> and other places. >> > ______________________________________________________________ > 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 > > ______________________________________________________________ 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
