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RFI From Miscellaneous Sources

The files in this section are recordings of RF noise from other sources that aren't as easy to categorize. If you can match noise at your location to one of these files then you can be confident that you know where your noise is coming from. Now all you have to do is find it and fix it!

  • Electric Fence

    Contributor: Mike, W8MW
    Noise Source: Electric fence, 1/8 mile away.
    Where Found: S9 on all frequencies below 10 MHz. Gradually weaker above 10 MHz
    Notes: " was an electric fence consisting of about 1000 feet of wire in a rectangle. Electrically, the fence was a full wave horizontal loop antenna resonant in the vicinity of 1 MHz, smack dab in the AM broacast band. With his permission I checked the fence charger unit and walked the fence line. Numerous poor connections were easy to spot along the length of the fence and especially around the gate area. It would have been nice to find a clear visual indication of arching or burning; or at least have the radio detect a louder signal to localize the exact spot, but no such luck. I suspected at some point a spark gap was the culprit and possibly the gap was intermittant causing the noise to temporarily go away."

    Click this link to listen: Sounds/w8mw-elec-fence.mp3


  • Carwash

    Added July 9, 2004

    James Lauth, Longwave DXer

    Noise Source:

    A local carwash

    Where Found:

    Recordings were made on 300 kHz in the longwave band.


    A very interesting recording. Here's what James said when he submitted the file: "As spring of 2003 approached, my longwave listening sessions were occasionally interrupted by a strange type of interference. It consisted of a distinct series of whirring, growling, and humming noises that lasted about a minute, and sometimes repeated themselves. The interference was relatively strong, and more or less blanketed the longwave band, which made beacon hunting impossible. As the days got warmer, the interference became more frequent.


    I bought and read a couple books on RFI, and began checking the electrical appliances around the house. I eliminated all of them, and so concluded that the source of the noise must be outside the house. I really had no idea where to start looking, but the nature of the noise made me think of motors and pumping, like a dishwasher.

    Then I recalled that there was a gas station about a block from my house that had an automatic car wash. I walked to the car wash and waited for a car to pull up. Sure enough, the equipment was making basically the same noises I heard on the receiver. My guess is that the pump motors are dumping noise onto the power line.

    I made the attached recording this morning on 300 kHz in CW mode. It is a bit longer than you wanted, but the wash cycle is almost exactly one minute long, plus five seconds of silence on each end, or at least as silent as longwave ever gets.

    Click this link to listen: Sounds/carwash.mp3


  • Invisible Dog Fence

    Added August 31, 2005

    Jim, W1UK

    Noise Source:

    Invisible dog fence

    Where Found:

    VLF through 5 MHz


    "The manufacturer is Innotek Inc.

    The model is UltraSmart IUC-5100. FCC id KZ3050241. The label states it is a Part 15 device. The modulated crud is detectable from VLF up through 5 MHz and is S-9+ on 160. The harmonic appears every 8 kHz. My recording is from 160m and is in this order:
    1. AM 6 kHz bandwidth
    2. LSB 3 kHz bandwidth
    3. Tuning up from 1800 in LSB showing harmonics every 8 kHz.

    You can hear how loud it is as I tune through W1AW!"

    Click this link to listen: Sounds/w1uk-dogfence.mp3