SW on computer speakers?

[CT22]

My girlfriends computer speakers have been picking up a faint signal for some now. After some listening closely we figured out its the World Harvest Radio (religous programming) on various SW frequencies.

Somehow the computer speakers are picking it up and we dont understand how. The signal never fades and the audio is very low and you cant get it any louder by turning up the volume...

Any idea how this could be happening? Did some jesus freaks load up a streaming programming that running in the background?

We are in CT and her PC did this when she lived in MA as well.

OK, we disconnected her wireless card so the internet connection dropped out and the signal is still there, so its definetly getting into the PC somehow. Very strange!

 

[DX-300]

It definately sounds like RF noise or interference likely caused by a strong transmitter. I can make this same thing happen if I transmit my CB in the house, as when I do that I can hear my voice faintly over my RCA stereo if its on, no matter if its tuned to the radio, or cassette or CD or just idle.

One can even make a simple radio frequency signal tracer, which acts like an untuned crystal set and when you probe around metal objects it allows you to hear all kinds of AM signals and noise through the earphone. Using one I built with my electronics project kit I could hear the strongest AM station here by just touching the probes to the screws on a light switch plate or some other metallic objects around the house that are basically acting as antennas.

The only thing I don't have that much knowledge of is how to prevent/reverse this problem if its causing problems, like what filters or devices are necesary, or if something simple can be done with wiring etc. It also seems to me that some devices are more sensitive to it than others.

 

[CT22]

I thought of the same thing but no wires on the PC are long enough to be good HF antennas. I suppose the AC wiring in my condo could be good enough of an antenna. It just seems strange that the signal is always strong and clear. HF propagation changes with the daily MUF.

 

[DX-300]

Looking at the technical data for World Harvest Radio http://www.whr.org/index.cfm/fa/techinfo it appears they have a 60 million watt tower (yes I said 60 MILLION WATT!!) in Greenbush Maine transmitting to Africa and the Middle East and another in South Carolina. To my understanding of this technical data it then appears that the transmitter is both VERY strong and relatively close to you perhaps. If thats the case that would definately explain why its comming in at a constant strength.

 

[Thayne]

That's a lot of RF close to you. First I would try another speaker set; (Just borrow one to try) if that doesn't work then you probably need some kind of notch filter tuned to the Freq. It looks like they are all about 7 to 15 Mhz. If they are transmitting multiple freqs from each site you may be SOL. Try calling the station for suggestions.
We used to fight that problem in regular telephones all the time with people that lived near radio station transmitters.

 

[kb2vxa]

Hi Spatch and all,

There's a number of ways to reduce or eliminate RFI but they're well beyond the scope of this discussion. For proper information the ARRL among others have published much on the subject. In the long run it's probable that better speakers are a better solution than going through all the trouble of filtering the ones you have and if you're like most people you lack the technical skills.

What I find puzzling is how a transmitter in MA could cause RFI in CT regardless of the ERP or the fact you're on the edge of the beam path if that's the site beaming to Africa. FYI, radiant energy like gravity diminishes by half at the square of the distance so by the time that megawatt signal reaches you it can be measured in microvolts.

WHR is also carried by local brokered air time stations, do you receive any other programming at other times? How about someone with a carrier current (through power lines) intercom sort of device? Do you have a CBer nearby who likes to broadcast? Rhetorical questions, I'm not a bloodhound with a tin foil nose. (;->) That last isn't so far fetched, I once RDFed a ham broadcasting Gospel music on CB channel 14.

Like the man said, that's a lot of RF close to you so you need look no farther than your own back yard.

 

[jparks29]

I'll bet ANY amount of money that the speakers are AMPLIFIED speakers..........

they're known to have poorly shielded RF amps.......they will pick up EVERY little bit of signal that gets in it...and amplify it........

unplugging the speakers from the computer wont help it... only thing that will help it is to not use the amp, or... wrap the speakers in foil, put it in a metal box, or seal it in concrete.....hehe....

 

[N4UYV_Al]

Greenbush Maine ta East Hampton Ct is a couple hundred miles & then some...