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Posted by Bruce WA1HGJ on January 15, 2025 at 14:04:25.
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For a long time I've heard pure carriers of various strengths and various frequencies in the LW band. The standard explanation of course is that these are utility signals coming in over the power lines, or something equally unknowable, so I've generally ignored them. They have tended to be in the 130-160 kHz range, but sometimes different frequencies on different days, it seems. But now and then I'll hear a really, really strong carrier which to me casts doubt on the "far away utility signal coming in on the power line" hypothesis. Plus, I can never detect any modulation or variance, pretty pure notes. Last night there was a really strong carrier at 153.93 kHz, registering 20 dB over S9, massive, with it's first harmonic at 307.86 kHz essentially the same strength. The strength of these signals, and the fact there was no harmonic filtering, suggested the source was actually inside my own house (it was an LED "light bulb over my head" moment). A little Google sleuthing revealed that switching LED driver frequencies can be 40 kHz up to 1 mHz. Of course, we've got LED lights all over the house like everyone else these days. Someday - not soon likely - I'll try to correlate specific lights being on or off with the strongest LW carriers I hear (weaker ones may be at my neighbors' places), but I wondered if anyone on this Board has any thoughts on likelihood of this? These are pretty pure, stable notes, not junky, i.e., very clean carriers. Any thoughts? Tnx es 73, Bruce WA1HGJ
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