Radio tower interference problem

[HP_Ellison]

Here’s the situation-

I live right down the street from a radio tower. Now, whenever I turn on the yamaha speakers that I bought for my computer, I can hear the sounds of the radio station coming through. Sometimes it’s so strong that I have to turn the speakers off, but sometimes it’s rather weak. This seems to depend on the placing of the speaker wires and even the speakers themselves, but sometimes there is simply no way to deal with it. What can I do to deal with this? Also, why is it that the problem isn’t nearly as bad with my much cheaper apple speakers?

[Duck_Duck_Goose]

From the FAQ.

http://www.altecmm.com/Altec/support/faq/m_problems.htm

If you are living near a radio tower you could have interference caused by radio frequency. Try moving your speakers to see if the RF goes away; if not, putting ferrite beads (which can be ordered from our Consumer Support Department) on the speaker cables may help. As an option, purchase a stereo cable from your local retailer that has a higher percentage of shielding.

And there’s some tech stuff here. Maybe get an “RFI filter”?

http://www.56k.com/pastnews/98090612.shtml

[Arjuna34]

There’s some good info here, especially about half-way down the page:

http://www.arrl.org/tis/info/rfiaudio.html

They describe an RFI filter you can build for about eight dollars:

Wrap ten to fifteen turns of speaker wire onto an FT-140-43 ferrite core. (Use an FT-240-43 if the speaker wires are large, and use -73 material for interference from 80 or 160-meter signals.) The common-mode chokes should be installed right at the amplifier. (If the system uses amplified speakers, you should install one at each speaker,
too.)

The FT-140 core is $3.75 from Amidon Associates. The “140” means 1.4 inches in diameter. Basically this is a ceramic iron donut 1.4 inches in diameter.

You can also buy an RFI filter kit from MFJ- it’s MFJ-701 for $14.95.
Arjuna34

[ZenBeam]

This probably won’t work, as Arjuna34’s link implies it’s a common mode problem, but it’s free to try: twist the speaker wires so they form a double-helix along their length. (Assuming he speaker wires a twin lead, not coax. If they’re coax, just ignore me. )