Practical advice needed: What do I do now?

Bob DeMattia
Fri Oct 1 10:31:24 EDT 2010

The noise doesn't necessarily have to follow the AC power line...the power
cord itself can
serve as an antenna.  Noise generated in the power supply radiates out of
the power cord.
An RF choke (as  I mentioned in my earlier post) placed around the power
cord and as close
as possible to the computer chassis will block the RF noise from going down
the power cord.

This assumes of course that the power cord is the culprit, which you won't
know unless you
look for the leak first as I suggested.


On Fri, Oct 1, 2010 at 10:25 AM, Dan.Strassberg <>wrote:

> Not suppressor--filter. But that assumes that the noise is getting
> into your radio via the AC power line. If the radio is battery powered
> (and you unplug it from the AC line), do you still have the problem?
> If yes, filtering the AC that feeds the computer system will not help
> or won't help much. However, if unplugging the radio from the wall
> helps, then filtering the AC that powers the computer might work. It
> is likely to (but not guaranteed to) work better than filtering the AC
> line that powers the radio because filtering the line that powers the
> computer will reduce the noise that is getting onto the house's AC
> wiring and is radiating into the radio. The kind of filter you need is
> a low-pass filter, which lets the AC power through but carries the
> noise to ground. Ideally, you should plug the filter into a three-wire
> AC outlet (one with receptacles for two parallel blades, of which the
> narrower one is AC Hot and the wider one is AC Return. A third round
> or U-shaped opening is the ground receptacle). If you don't have
> three-wire outlets in the room, or if the ground terminal is
> electrically floating--which is illegal and hazardous but is often the
> case--the filter is unlikely to be effective.
> -----
> Dan Strassberg (
> eFax 1-707-215-6367
> ----- Original Message ----- From: "Doug Drown" <>
> To: "=?utf-8?b??=" <>
> Sent: Friday, October 01, 2010 9:52 AM
> Subject: Practical advice needed: What do I do now?
>  I just set up my old computer in the house where I'm newly residing,
>> and the noise interference on AM is awful. FM is fine.
>> I didn't have this problem at all with the computer I had borrowed
>> for the past several months. II gather what I need is some kind of
>> suppressor, but I have no idea what. When it comes to computers, I
>> can write, send, save, upload, download, maneuver around the
>> Internet, and create a website (kinda-sorta), but when it comes to
>> the tech ends of things I'm pretty ignorant.
>> -Doug

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