QRN Any Ideas?


Steve VA3FLF/KM4FLF
 

This what I have been putting up with the last 3 or 4 weeks. It started suddenly. I have tried tracking times, driving around with AM broadcast radio on, but I can not seem to isolate this. I thought grow lights, LED's? The times are totally random but seem to be more often in the evening but sometimes goes way into the late morning.

The recording is 40M and I am 10db over. 30 /20 is effected but slowly gets weaker up the band. 40 and below become completely unusable.

Help?

Steve
VA3FLF


Stephen KO4CVU
 

Steve,

If you haven’t already watched a series of YouTube videos about radio interference on RASA’s channel https://youtu.be/bkCvjyjKtpc , you might pick up some good pointers. I built one of those non-resonant loops that is described in one of their videos. When my RFI was at the worst, I was able to trace most every run of romex in the house with the loop and my radio. The ones through the attic to the A/C heat exchangers were the worst. Like yours, my interference would come and go. Wouldn’t you know it, I had strung up a dipole in the attic that run roughly parallel with those 220 volt lines! I am confident that the interference was coming in on the power line. A “coax noise filter” in line with the antenna cable didn’t help. Neither did a phase cancelling box that I bought.

I can’t say for sure that the construction of a multi-story storage facility near the neighborhood was the source, but the noise has diminished significantly now that construction is complete. I can remember noticing that they were arc-welding the steel structure. Unfortunately, I didn’t not recognize the potential connection during construction. 

The noise that I was experiencing was more sporadic when it was there than yours is so yours may be something totally different. Since you can’t listen to the radio much due to the interference, take time to view RASA’s YouTube videos. Maybe you’ll pick up a few ideas from them.

And F. Y. I., I am still waiting for a reply from a fellow at the ARRL to a sound clip of my interference that I sent with an email. I understand that they are going through some reorganization at the HQ so I guess it will be a while before I hear anything from them.
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Stephen, KO4CVU