How to Stop Radio Frequency Interference with Ferrite Chokes

As radio frequency devices become more common, radio frequency interference is becoming more of a problem. Radio frequency interference can manifest itself as a hum or buzz in a surround sound system, radio, telephone system, etc. Ferrite chokes are an easy way to prevent and cure problematic radio frequency interference for only a few dollars at a local electronics store.

Ferrite is an iron alloy that is affected by a magnetic field. Ferrite chokes are either toroid-shaped or snap-on cylinders that are used to prevent outside radio frequency interference from entering into an electronic system. If you suspect that you a hum or buzz in a sound system, for example, is caused by outside radio frequency interference, you can try to eliminate the RFI by wrapping the device's power wires a few times around a toroidal ferrite choke. There are also smaller, snap-on ferrite chokes that are cheaper and smaller, but these can be less effective than toroidal ferrite chokes.

Unfortunately there is no way to predict whether a ferrite choke will successfully cure or prevent radio frequency interference. There are usually too many factors affecting radio frequency interference to know whether a ferrite choke will be successful. However, given that ferrite chokes cost only a few dollars, it is usually worth the risk to find out if the problem can be solved cheaply with a ferrite choke before more expensive means become necessary.

Radio Shack sells a variety of ferrite chokes in various sizes. Radio Shack part numbers 273-067 and 273-069 are smaller snap-on ferrite chokes that you can snap around a power line or audio/video cable. Radio Shack part number 273-105 is a slightly larger snap-on ferrite choke for surrounding larger wires. And Radio Shack part number 273-104 is a snap-together toroidal choke around which you can wind a wire several times for even greater protection against radio frequency interference.

Ferrite chokes work best when the radio frequency interference is not too severe, but a larger choke will likely do a better job in preventing radio frequency interference. Each of the above ferrite chokes sells for less than $10, so it is not expensive to try to solve an RFI problem yourself with one or more ferrite chokes. As mentioned above, there is no way to know beforehand whether a ferrite choke will successfully solve your particular RFI problem, but ferrite chokes are worthwhile to try because they can be moderately to highly successful in isolating an electronic system from outside radio frequency interference.