I’ve got a headphone type wire that goes from the speaker output on my computer to the aux input of my stereo. This wire acts like an antenna for a local talk radio station & it’s driving me nuts. Not only is it talk radio, it’s wacko conservative talk radio.
Anything I can do prevent this?
You can try a snap-on ferrite choke, available at RadioShack and other electronic component dealers.
You might also just try re-orienting the wire. Wrap part of it in a loop. Properly grounded sheilded wire shouldn’t do this.
The shield isn’t always grounded, particularly in battery-powered devices. In cases like this, it’s usually the shield itself carrying the RFI, not the inner conductors.
I wouldn’t think the sheild would be touching the inner conductors and conveying the radio energy to the speakers unless the wire was bad, if indeed that was what was picking up the signal. In which cased I would recommend getting a new wire.
The long interphone cords I used to work on would get this problem all the time. The sheilding would wear out from the heavy (ab)use the cords got, once this happened they invariably became antennas when oriented correctly, usually to an AM band station.
Ground can be the metal case of an object, it doesn’t neccesary have to be earth ground. Airplanes use the airframe, for instance.
The shield is often used as the common conductor in stereo headphones and similar applications. In other words, it’s part of the signal path.
Not to mention Walkmen are made of plastic. The tuner circuit itself will be shielded in a metal “can” but everything else is open, so to speak.
I’d try a ferrite at the headphone plug - usually what happens is the RF is picked up by the outer conductor (in the case of Walkman headphones, it’s not a shield) and gets rectified and demodulated and goes back out to your ears. If you’re capable at soldering, try putting a couple small ceramic caps across the headphone leads (each inner conductor to the braid) at the plug. My memory’s really fuzzy on the specifics - perhaps something like .001 uF? The idea is to short out the AM radio and not affect the audio.
Thanks for the suggestions, all.
Thought I’d let you know I solved the problem tonight while being forced to listen to some late-night jack ass talk show host.
I just plugged the cord into the headphone jack on my computer instead of the speaker jack. Voila, no more radio bleedover, but I still get the high quality sound from my stereo.
Don’t ask me why that worked, but I’m thankful it did.
…How 'bout a Faraday Cage?