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Picking up AM radio on laptop - how to cope?

  • I hope this is the proper subforum for this, if not apologies. I recently bought an ASUS laptop from newegg (specs unchanged so far) and since buying it I've only used it at home. It picks up an AM radio station nearby and plays it quite loud whenever I use the headphones. There may be an improper ground on our house's electrical system because on my old laptop and speaker system I could hear a very faint radio signal; however on this one it is LOUD and it simply doesn't go away unless I unplug.

    If there's any sound playing, then the radio interception stops. It only occurs on headphones. Before anyone says "well don't plug in your headphones if you aren't listening to anything, dummy" it is pretty annoying to be doing some audio editing, and in between playing clips I get blasted with Spanish radio. It's like constant bachata torture.

    I don't know if this is related, but when the headphones are plugged in, more than one audio stream will cause it to "switch" to the speakers. This is my first experience with IDT audio, so no idea if this is a common problem. Obviously this is a minor annoyance when I'm playing a game at night and suddenly I get a skype message, causing my game sound to blare out of the speakers and wake everyone up. However this would be a huge problem at a library or if I took my laptop to the office when everyone hears about 5 seconds of my music every time something else on the machine causes a sound. Since these both only occur when using headphones I think the problems are connected.

    Could I use some sort of AC filter? Is there something I can do to make sure the laptop is properly wired? 

  • Hi Torgo!

    The problem you're having is common to Amateur Radio and CB with near by radio stations. The problem is the power cord and your headphone cable are acting as an antenna.

    Normally we fix that by adding a "Magnetic Ferite Choke" to both cables. You should be able to pick those up at your local Radio Shack Store. You want the chokes close to the computer as you can get them.

  • Thanks n0lxx. As I understand it, if the power supply adapter should eliminate this problem (in theory) IF the outlet is truly grounded, but a slight variation from "zero voltage" on the ground prong will cause enough current to create the "antenna effect". Is there any other cause? I ask because after a lot of remodeling, we had an electrician come in specifically to inspect and test all outlets and we paid good money to make sure there were no problems like this.

     A little inconvenience of getting a small device is no problem, but if there is an improper ground then I'm worried about the safety hazards. Is there anything else that could be causing it?

     Two things I noticed:

    1.  My power supply that the mfgr provided already has a ferrite bead on it, right next to the point where it attaches to the laptop.
    2. When I roll back my audio driver (IDT High Definition Audio codec), the problem stops. However I also lose the StereoMix option for my recording devices, which means I can't record my audio and that is more important to me than blocking out Spanish radio.
    Don't know if that's relevant...with the ferrite bead on the power supply I shouldn't be hearing any of this. Also I have no idea why audio keeps getting routed from my headphones to my speakers, but it seems related and almost like a problem with the internal wiring of the computer.

    Thanks again!

    [edited by: Torgo]
  • What we run into is the length of the power cord. What you're getting is called a "harmonic" of the frequency that the radio station transmits on. Also, since you're close to it, the power alone can cause it. Adding a bigger ferrite choke SHOULD help eliminate it. Radio Shack has 6 different ferrite chokes available. The third and sixth on the list are common ones Ham Operator's would use. (See how the cord wraps through the center of the core. Each time you go a full circle and come back to the same side you started at, we call that a turn. A few turns like that should help.)

    It sounds strange that simply rolling back the driver should eliminate it to me though. Make sure there isn't a more current driver for the laptop. Check other boards to see if anyone else is having the same problem as you are with their same model laptop.