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#4
March 10th 07, 03:11 PM
posted to rec.radio.scanner,alt.radio.scanner,alt.ham-radio.hf
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Carrier tones every 15 kHz in 10m band
"Edmund H. Ramm" wrote in message ... In "Ron Baker, Pluralitas!" writes: "DougSlug" wrote in message ... While tuning through the 28.3 to 28.5 MHz portion of the 10m band in USB mode, I get what sound like carrier tones very evenly spaced every 15 kHz starting at about 28.3 MHz. I am using an AOR AR8600MkII receiver with an AOR SA7000 antenna mounted on a mast outside. I am located in central NJ in the Princeton/Trenton area. What is the source of these tones? Thanks, Doug The horizontal sweep of television sets is 15750 Hz. Switch mode power supplies operate anywhere from 10 kHz to 100 kHz. It is not uncommon for either of them to ring and generate harmonics in HF. In the case of switch mode power supplies the spikes IMO would be 120Hz apart (100Hz where I live). And most of the rf energy is spilled from abt. 1 to 7 MHz, with almost nothing left to be found on 28MHz. 73, Eddi ._._. -- e-mail: dk3uz AT darc DOT de | AMPRNET: If replying to a Usenet article, please use above e-mail address. Linux/m68k, the best U**x ever to hit an Atari! The mains frequency has little to do with the noise that a switcher can generate. A switcher rectifies and filters the mains to DC then uses a switching transistor to drive a transformer at a much higher frequency. Tens of kHz typically. The higher frequency allows the "magnetics", i.e. the tranformer, to be much smaller physically than a 60 (50) Hz transformer. That plus the on-off and not linear nature of the switch allows switching power supplies to be smaller and more efficient than linear supplies. It is the switching, with sharp edges, that generates high frequency components. I've seen poorly designed switchers generate harmonics into the hundreds of MHz. -- rb |
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