Posted by Bruce WA1HGJ on January 17, 2025 at 15:14:53.

In Reply to: Re: LED driver frequencies in LW bands? posted by John Davis on January 15, 2025 at 21:54:10.

Thanks for both of your replies, Ed and John. Good information therein and more food for thought. I do have some updated information that supports John's position to not prematurely rule out PLCs as potential sources of even the strongest carriers in the LW spectrum. The other night, I woke up ridiculously early and couldn't get back to sleep, so decided I'd take advantage of the hour (4 AM) to check out the quieter LW bands. After making a pot of coffee in the near-dark (relevant to the story since there were no LED lights on in our house), I started listening and almost immediately heard a very strong carrier (20 dB over S9) on 125.67 kHz. I don't recall hearing a strong carrier on that frequency before (usually in the 130-150 kHz range as mentioned in my original post), but as I've not kept careful logs of carriers (to Ed's point - might be a good idea), I can't say for sure. Anyway, there it was booming in on 125.67 with no LEDs on in the house--so it wasn't that. Then, to my very big surprise, 45 minutes later when I went back to that frequency, it was gone. Totally gone. And I had not turned anything on or off, and there were no LEDs on in our house. So, here was a very strong pure-note carrier on 125.67 kHz at 4 AM, that just completely disappeared. Unlike my LED hypothesis in my original post, I can't see how this came from within our house, and the ridiculously early hour suggested it probably wasn't in our neighbors' houses either. So, this sounds like it might be one of PLC "go/no-go indications of transmission line integrity" that John mentioned in his post. Anyway, new information I thought I'd share here. Wish there was some way to "track" these things better - sort of a PLC DXing activity, if one could ID the originating site. Maybe that's a project we can all take up when the last NDB is finally decommissioned. 73, Bruce WA1HGJ

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