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What is RFI?

What is “RFI”?

  • You are chasing an elusive DX station and you finally found him on 7.215MHz.  You get ready to push the button on the microphone, and your significant other turns on the stereo to listen to some music.  As soon as you start talking, you hear your own voice in the stereo speakers, and then the yelling starts.     
  • You just finished installing that new dual band radio in the car.  You hop in the car and drive off to check your signal from several locations.  You get on the local repeater for a signal check and get a reply that there is a ticking noise on your signal.  You pull over and shut the engine off, the other ham says the ticking noise is gone now.     
  • You install a 3500 watt solar power system on your roof with inverters, batteries, a transfer switch, and all the necessary wiring.  Your power bill is half of last month’s so you feel good about this investment until you find out that the noise level on all your radios has increased dramatically, especially on bright sunny days.     
  • You decide to make some changes to your home to save money on your power bill along with your newly installed solar power system so you go out and buy LED lighting to replace the old incandescent lights.  The up-front cost is high but the new lights last a lot longer and use a lot less energy, ahh the savings!  You then find out that the new lighting is driving the S-meter on your HF rig to new high’s.  You test this theory by turning off all the lights and watch as the S-meter slowly goes back to normal.

These are but a few examples of what is commonly referred to as “RFI” or “EMI”, (Radio Frequency Interference or Electro-Magnetic Interference). There is a long list (and getting longer with new energy technology devices) of things that cause RFI.  The ARRL is working with industry representatives to incorporate design elements in these new devices that will reduce or eliminate RFI, but it’s a slow process. The ARRL has an extensive library of information on RFI at http://www.arrl.org/radio-frequency-interference-rfi. Check out some of the sources and mitigation methods to help you with your own RFI issues.  Another source of information is the regulatory information at http://www.arrl.org/rfi-regulatory-information