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RF interference on AM/FM

Posted by macmaven (My Page) on
Sun, Dec 24, 06 at 14:39

We just finished remodeling our house, adding several dimmer switches for the lighting. I now find that our old radios are getting so much interference from these things that I cannot listen to anything, AM or FM, unless I turn off all the lights in the other rooms. (We have no cable radio or external antenna option here, so we are stuck with traditional broadcast radio.)

Does anyone know of a solution, short of uninstalling all the dimmer switches?

Are newer radios any better at filtering out this stuff? I'm talking here about older (20 years or more) table and clock radios.

Is there some sort of filter we could install on the radios?

Follow-Up Postings:

RE: RF interference on AM/FM

AM radio accepts every bit of electrical inteference out there including lightning strikes miles away. FM grew because it did not. I think I would invest in an inexpensive FM radio and if you still have interference I would suspect those switches or something in the wiring.

RE: RF interference on AM/FM

Move the radio to other locations around the house and see what happens. Lots of the white noise in AM can be caused by poor reception. If you have a lot of wiring and electrical appliances on the walls around the radio, these too can interfere with reception. You can improve AM reception by adding an AM antenna to it, but you can only do that if the radio has an external AM antenna connection. If you buy a new AM/FM receiver, you will notice that it comes with an external AM antenna for connecting to the back of the receiver. That's the type of antenna I am talking about.

Check with Radio Shack and see if they sell um-powered AM antennas that you can connect to the radio, but make sure that the radio has such a connection at its back.


I went back and re-read your message, and realized that the problem is with both AM and FM.

1. Move the radio to other locations around the house
2. Try external (not outdoors) antennas
3. Make sure that the electric ground rod near the electrical meter (outside the house) has been properly installed, and that the clamps are tight around the rod, and the electric box. Also, find out from an electrician if the ground wire should also be clamped to the plumbing in the house. I have no idea if this is a code requirement, but my house was built with the breaker box grounded in a "Y' type of connection.

Finally search "AM radio antennas" on the Internet. Here is one (cut & paste):

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