[ADXA] Noise

[Steven Rutledge]

Dimmers on home lights can be a real problem.  My utility company traced the noise to a neighbor’s home.  It was on the market.  I was friends with the owner.  When they moved, he gave me a key to the house and I took an electrician in with me and he removed all the dimmer switches and replaced them with conventional ones.

Another time, utility workers found a house about .5 miles from me that had a huge signal coming from inside.  They knocked on the door, owner let them in and they discovered a faulty connection in their HVAC.  Repairman called, noise gone same day.  Owner was told it was a fire hazard.

Joel is right about non-compliant devices.  As far as power line noise.  I use a small receiver, in AM mode, around two meter band.  When I find suspected pole, I hit it with a large hammer.  That will tell you if you have the right pole. Just don’t tell your utility reps.

Steve, N4JQQ

> On Mar 24, 2026, at 9:15 AM, Joel Harrison, W5ZN via ADXA <adxa at mailman.qth.net> wrote:
> 
> 
> ADXA Folks,
>  
> Second to antennas, noise is my favorite topic to discuss. Unfortunately for radio amateurs, the exponential expansion of cheap consumer devices that generate RF has significantly complicated our ability to receive weak signals and many times impacts higher amplitude signals as well. Years ago, the radio amateur was the source of RFI to televisions, stereos, and other consumer devices but today the tables have turned.
>  
> Our initial reaction to noise is it must be power line interference but in over 90% of the noise issues I am aware of today the source is not sparking or arcing from power line issues. Mark, K5OO, who has provided details here worked professionally in this area and has extensive experience and knowledge with power line interference. Power line interference has some unique characteristics and Mark has provided photos of what that looks like and it won’t occur on just one band. It is easy to identify but sometimes quite difficult to track down, especially if it is an intermittent source.
>  
> A noise source from a consumer device is much more complicated and difficult to locate. As I have noted, and Jussi is now experiencing, consumer devices can generate a significant noise source on one band in a small, discreet bandwidth or over a larger bandwidth. The source may even “sweep” across a frequency segment and most important it may not be in your house! I’ve noted my 160-meter noise source to the east is originating from 1,500 feet away, that’s over ¼ mile! One of the greatest offenders are switching power supplies, wall warts, and internet routers and other LAN equipment can be just as bad. Grow lights are notorious. Kim bought a lemon tree last year and this winter it was brought in the house and a grow light was used to provide “artificial” sunlight a few hours a day. That darn thing just obliterated my receiver!
>  
> Obviously the first approach is to kill power to your house and any external buildings and run the radio on a battery to see if the noise disappears. If it does there is a simple procedure to follow to track down the source. If the noise is still present then things get complicated because the source is outside of your control. My house, shop, and station are as clean as a hound’s tooth but I see junk originating from the neighbors’ homes.
>  
> There are tons of stories of various noise sources being identified. My buddy W0FLS in Iowa spent a year tracking down a noise source on 160 meters to the NE toward EU, a vital direction where you don’t want to have a noise source. The source was finally identified as a switching power supply out in his shop that was radiating from the power cord that was acting like an antenna. K3LR had a significant noise source appear on 15 meters one day. Everyone has seen Tim’s massive antenna farm on video but what you don’t know until you’ve been there is he is surrounded by houses. His noise source was tracked down to a battery charger at a neighbor’s house across the street.
>  
> As I noted, the examples are many but my point is we live in an RF environment that is overrun with noise generators today and power line noise is the least likely source. Over the past 15 years my noise floor on 160 meters has risen 10 dB, not from power line issues but consumer RFI generators. That is significant when trying to copy very weak signals, even with FT8.
>  
> Now, don’t just “GET IN THERE AND WORK ‘EM”, but GET IN THERE and find your noise sources and eliminate them. Noise is Grim Reaper of radio reception!
>  
> 73 Joel W5ZN
>  
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