Street Lamp QRM?
After many months with severe buzzing on the HF bands in the evenings it looks like there is a promising lead finally.
The buzzing has been S6 to S9 with the worst being 40m. It has been especially maddening as sometimes it would randomly stop and the clarity would be amazing.
But what was causing this? Power lines someplace seemed like a culprit, but where? Driving around trying to find noise peaks from the mobile wasn't to help as the antenna on the car just wasn't as sensitive as the big antennas at the house and the ignition noise was just as strong as the noise being hunted.
A friend then mentioned how he was having bad noise and found it to be the street lamps on his road. That after getting the power company to service the lights the bands were once again quiet for him.
So what is up with the lights? Apparently it is normal during turn on of those popular yellow/orange street lamps for them to make RF noise that lasts a short bit (20 or 40 seconds).
When these lights start to go bad they can sit in a perpetual turning-on state. They can turn on and as soon as fully on immediately turn off and then start turning on again. Or they can sit in a half turned on state. When neither fully off nor on fully on they make RF noise.
A few days later while listening to 20M in the afternoon with the band sounding clear, the buzzing suddenly started. A quick look out the window shows it was starting to get dark out. The street lamp in front of the house was still out but it was that time of day street lights would be turning on. After 20 seconds or so the buzzing stopped. Was that a street lamp turning on? Not sure, none within view of the house are on. The buzzing starts again, a quick look out the front window and the street lamp in front of the house is just starting to turn on. Shortly thereafter the buzzing stops, another look at the street lamp and it looks fully on.
Back to the radio, more buzzing starts but is fainter, perhaps a lamp further away? More listening and the pattern keeps repeating, sometimes stronger, sometime weaker, sometimes overlapping. But it is a buzzing that occurs for a 10s of seconds and then goes away. Yes it makes sense, it is the different street lamps coming on in the area.
Eventually a buzz picks up and doesn't go away expect for the occasional few seconds. Perhaps this is a faulty light? It is now dark out, all lights should be on. The street lamps that can see from the house are all fully on, but are there any in the area not working right? Its time for a drive.
During a drive around the neighborhood reveals three street lamps stuck in a half on condition, one turning off every time it turns on and two completely off. A total of 6 faulty lights within a mile. One of the ones completely off is behind the house and if that is making noise that could be the biggest culprit.
With the pole number recorded for the problem lights and reported to the electric company now we just need to see how long it takes for them to get fixed and see if this resolves the nighttime buzz.
Keeping our fingers crossed on this one.