The spectrum analyzer runs all the time, usually showing the range from 150kHz to 1800kHz, and today I noticed a pulsing wide-band peak centered on about 400kHz and spilling into the low AM band, with a reading of 30dBm.
I tuned the Zenith to 400kHz and there was a blasting buzz that sounded like the radio was next to a microwave oven or x-ray machine.
Yikes, I thought, must be HAARP blasting our internal organs with radiation just like Alex Jones foretold. As the day went on the analyzer reading increased to 50dBm!
So I recorded the sound for another “strange reception report” for the next Low Power Hour.
But that hidden voice that tells me secrets of existence suggested I flip off the wall switch feeding 3-LED light bulbs in the ceiling fixture. The buzz totally stopped.
How come I hadn’t noticed the buzz before? Those bulbs were put in over a month ago to replace the compact fluorescents, which produced a terrible quality of light. Originally I’d only installed two of the LED bulbs, and they seemed fine, but the other day I added a third bulb.
Either the three bulbs together are generating the noise, or the third bulb has a problem.
Let’s devote a day to figuring that out.
Bulbs that radiate the public? Is that what they’re giving us?
Are the bulbs radiating? Or, are the bulbs injecting a carrier-current buzz that travels on the AC line? Can’t have it.
Please send reports of your bulb experience.
Oh Man!
Oh man, Carl! What an unexpected
problem!
I never would have thought that
LED bulbs would do that, and it
seems to me (radio aside) that
they are the best solution to
lighting. I hate the CFLs.
Can you switch them around, or
try them in different lamps, or
something like that? Or try various
combinations of them in that lamp?
Maybe we will all learn something.
I don’t know what, but you never
know.
Bruce, THE SLUDGE BROADCASTING NETWORK
Thanks and Some Results
Thanks Bruce, the SLUDGE BROADCASTER.
I have tried a few things with more to try at a later time.
I held a portable radio up toward the ceiling fixture and the buzz wipes out most of the AM dial, up to about 1500 kHz, where some stations start poking through.
Walking away, foot by foot, the buzz diminishes, but it can be heard all the way out 10-feet from the house.
I held the radio toward the power wires out in the yard and there was no buzz at all, so it is NOT carrier currenting its way into the neighborhood.
I just think that standing here at the work station, down below all that radiation, is probably not healthy.
Coming soon I will analyze each bulb individually.
LED’s and Switching Power Supplies
We changed out all of our traffic signal incandescent lamps for LED lamp assemblies.
The power savings is dramatic. But, we have noticed increased interference to AM vehicle radios at some intersections.
Each LED lamp assembly contains a small switching power supply. I’ll assume it is the source of our noise.
Each assembly carries the FCC Part 15 notice regarding interference.
Valuable Input
MRAM has given the cause of the RFI (Radio Frequency Interference) from SOME LED bulbs. Those switching power supplies.
I now have good reason for limiting the problem to only some of the bulbs and not all.
I removed bulb number three, that is, the 3rd bulb recently added to the ceiling light. Result?
The LW (Long Wave) radio spike is gone.
I have two good bulbs.
Since they are somewhat expensive, I will return the offending bulb for an exchange. Maybe the next one will be alright.
Other Vulnerabilities
“We changed out all of our traffic signal incandescent lamps for LED lamp assemblies. The power savings is dramatic. But, we have noticed increased interference to AM vehicle radios at some intersections.”
Those also have a vulnerability to…..well perhaps I shouldn’t say it here because that might cause a “monkey read..monkey do” scenario.
But I will say this..those LED traffic light assemblies not only cause localized broadband spurious interference, but they are vulnerable to being interfered with as well. With what..that is confidential. So are the remote water and electric metering modules they use these days…also subject to causing broadband spur interference and vulnerable to being interfered with. Again, with what…that is confidential.
RFB