As our lives become filled with technology, the likelihood of electronic interference increases. Every lamp dimmer, garage door opener or other new technical “toy” contributes to the electrical noise around us. Many of these devices also “listen” to that growing noise and may react unpredictably to their electronic neighbors, including Amateur Radio transmitters.
Sooner or later, nearly every active Amateur Radio operator will have a problem with interference. This could involve interference to a neighbor's equipment, or, more likely, some form of intererence to Amateur Radio from the noisy devices that can sometimes even be found in our own homes. The good news is that most cases of interference can be cured! The proper use of “diplomacy” skills to communicate with a neighbor and standard technical cures will usually solve the problem.
These Web pages provide an overview and information to help find and fix RFI/EMI problems. The ARRL Lab staff recommends that hams with RFI problems purchase a copy of the ARRL RFI Book. This book, written by a number of experts, picks up where this web site leaves off, providing detailed information on the causes and cures for nearly every type of interference problem.
If you are having an interference problem, you should read the appropriate chapters of the ARRL RFI Book and the appropriate RFI pages listed on the menu to your left. Most of these pages have a brief overview of the topic,followed by links to the definitive ARRL and other articles about the type of interference you are experiencing. Most of the pages also have links to other sites with useful information about RFI. Follow all of those links and articles, then carefully follow the steps described for each type of RFI problem, follwoing the troubleshooting steps and using the types of filters described. This is important because in many cases, hams who try shortcuts, such as assuming that a ferrite bead of unknown material is the same as multiple turns of wire on a toroidal core made of the correct material, or hams who fail to turn off the main breaker in their own house to troubleshoot electrical noise may not fix a problem that could have corrected easily.
After you have read all of the applicable material and have tried the steps that look appropriate, you may contact the ARRL Lab staff for help iwth your RFI problem. The best way to do this is by email. Desctribe your problem completely, with model numbers and specific information (including approximate dates) of the steps you have tried to resolve the problem. In some cases, after you have sent the background emaill, it may be more efficient for everyone to talk directly on the phone with one of the Lab engineers. You can reach them by telephone at 860-594-0214, asking for help with an RFI problem.
It is impoirtant that you do read all of the material and followed the intiital steps described because the Lab staff will assume that you have done so, trying to pick up where they think you have left off. It's not a good use of your time for the Lab engineers to try to describe verbally in a few minutes time the important parts of the web-page and ARRL RFI Book material, because the material was written in a thorough, systematic way that is hard to duplicate on the phone of by email.
Do take heart that most RFI problems can be cured. By carefully following these steps, you can probably get your RFI problem fixed.
- A Ham's Guide To RFI, Ferrites, Baluns, And Audio Interfacing by Jim Brown, K9YC.
- In Compliance Magazine provides a tutorial on ferrites Using Ferrites to Suppress EMI.
- Audio Systems Group, Inc. Publications
Provides a number of articles and application notes related to sound systems. Some of these articles pertain to interference to audio systems from both power and RF sources.
- The EMI - RFI Page, by Mark Demeuleneere, ON4WW. In this page, Mark provides some interesting background on some of his more memorable RFI experiences in Belgium. As Mark puts it, “It took quite some time just to document these RFI cases. Imagine how much more time was invested in finding and solving them!”
- The EMI - RFI Page, by Chris Gare, G3WOS.
- Variable Speed DC Motor Washing Machine RFI Fix, by Gene Preston, K5GP.
- Grow Light Electronic Ballast RF Interference, by W0QE.
- eEngineer provides an EMI/EMC Glossary as well as several other RFI pages pertaining to RFI.
- Lutron provides both Applications Notes as well as RFI filtered dimmers in a variety of types, including low voltage.
- V-Soft Communications® LLC
Provides AM FM Zip Code Based Signal Strengths: Field strength vs. Zip Code
- RFI Enforcement Pages
- FCC Enforcement Activities and the Electric Utility Industry
Information on the ARRL and FCC cooperative agreement followed by a link list to FCC enforcement letters sent to electric-utility companies concerning harmful interference reports.
- FCC Part 15 Enforcement Letters
Information on Part 15 rules followed by links to a list of FCC enforcement letters sent to Part 15 device operators (other than power-line) about harmful interference reports.
- FCC Enforcement News and Web Links
- FCC to Utilities: Don't Look to Hams to Pay for Your Testing (Aug 27, 2009)
- FCC Issues Citation to Washington Company for Selling, Importing Unauthorized RF Devices (August 4, 2009)
- FCC Issues Citation to Part 15 Marketer (July 30, 2009)
- FCC Issues Two Citations in Longstanding Power Line Noise Case (August 30, 2007)
- FCC Cites Florida Utility for Interference to Radio Amateur (June 8, 2006)
- FCC Continues Crack Down on Marketing of Unauthorized Equipment appeared in the April 20, 2006 of Conformity eNewsBreaks
- FCC Proposes $1 Million Forfeiture for Marketing Unauthorized Equipment appeared in the March 9, 2006 edition of Conformity eNewsBreaks.
- KCBD-TV news story video about the FCC citations to Lubbock Power and Light and Xcel Energy in Lubbock, TX A complete video of the original news broadcst is also being made available for the ARRL Web site with the permission and courtesy of KCBD-TV Channel 11 in Lubbock, TX. (Play Video): KCBD-TV Broadcast August 27, 2007
- KCBD-TV news story video about the safety hazards of poorly maintained power lines in Lubbock, TX. A complete video of the original news broadcast is being made available for the ARRL Web site with the permission and courtesy of KCBD-TV Channel 11 in Lubbock, TX. (Play Video): KCBD-TV Broadcast September 24, 2007
- ARRL Helps to Clear the Air in Line Noise Cases, August 21, 2001
- FCC Enforcement Activities and the Electric Utility Industry
- Information for Electric Utilities
- Center for Devices and Radiological Health
Addressing EMI in medical devices
- Welcome to the RSGB EMC Web Pages
E-book-"The RSGB Guide to EMC" (Electromagnetic Compatibility)
- NARTE Certified EMC/ESD Consultants
A listing of NARTE Certified EMC/EMI and ESD Professionals who offer their services as consultants and/or contractors.
- EMC Standards
Contains a list that details some of the major electromagnetic compatibility (EMC) standards in place worldwide.
- Radioing eEngineer has a page on Radio Frequency Interference (RFI)
- The United Kingdom's Radiocommunications Agency has a Radiocommunications Agency EMC Awareness page with EMC/RFI information for the non-technical person and the general public.
- FAQ: The 411 On Radio Frequency Interference
- See www.aerorfi.org for information on interference in the aircraft band. Much of this information also applies to the broadcast and Amateur bands.
Naval Postgraduate School RFI Handbooks
Special thanks to George F. Munsch, W5VPQ for providing these documents. They contain useful and comprehnsive information for both RFI locating and noise mitigation. By Wilbur R. Vincent, W6PUX, George F. Munsch, W5VPQ, Richard W. Adler, K6RWA, and Andrew A. Parker, WV1B.
- Power-Line Noise Mitigation Handbook for Naval and Other Receiving Sites
This is a comprehensive manual that describes how to understand, locate and correct power line noise. A must for every utility or RFI troubleshooter.
- The Mitigation of Radio Noise And Interference From On-Site Sources at Radio Receiving Sites
Provides information when sources are located within the boundaries of a site. In most cases, these sources are electrical or electronic consumer devices.