RF Emissions

[monsignor]

My apologies if this isn't technical enough for this forum but it apparently has all the other forums stumped (or at least they won't take a chance on replying to this problem)

Recently built a pc (first time). I'm using an Antec 1030 case and it came with a Turbolink Switching Power Supply rated at 420w. The problem is that the computer is putting out emissions in the lower AM band upto around 900khz. I wouldn't be concerned but I have an older neighbor who is complaining that it's interfering with his AM radio stations. Also I get a whine through my phone (phone is right next to the pc).

I talked to my brother in-law who used to deal with pc shielding (government spook stuff) but he said that even if he could hook me up with one of his old sources I'd wind up spending 100's on a shielded box - ugh!

Any thoughts on how to shunt/choke the case? Also the pc is powered through a CyberPower backup. I did try powering straight to the wall socket to see if I might be having a ground loop problem but it didn't seem to make much of a difference.

Any ideas would be greatly appreciated. If you're going to get technical on building a shunt be gentle it's been 20yrs. since I did calibration and I've forgotten more than most people will ever know.

 

[bizmark]

(bump)

I have no idea, but I'm interested to hear if others have suggestions.

found a link for HAM operators with noisy computers...

There were a lot more links that looked informative with this search

 

[CTho9305]

you sure the PSU is causing the interference? it may be something else, possibly not even the computer.

 

[Heisenberg]

Surrounding the computer with a conductor (basically a Faraday cage) would reduce the radiated EMI. It wouldn't have to be a completely solid encosure - chicken wire-type setups are just as effective as a solid piece. I'm not sure how practical of a solution this would be though. This is more or less how the gov't.-spec shielding you mentioned works. A simpler solution would be to move the computer, if that's possible. Even 10 or 20 feet can make a substantial difference.

 

[RSMemphis]

So, when the computer is completely unplugged, does the AM / phone problem still occur?

 

[dnoyeb]

Are you using a metal case?

Is your ground line properly connected and grounded?

I would NOT expect your neighbor to be feeling interference through-the-air from your computer. Maybe he is stealing power from your house illegally Meaning if your plugged into a outlet on the same or close circuit-breaker, then maybe an AM radio would see interference, but I thought am was 10KHz anyway?

 

[MillionaireNextDoor]

My thinking is that a new PSU from a non-generic source should alleviate the problem; I haven't heard of problems coming from Antec or Enermax PSUs so they're your best bet. Anyway, this will be cheaper than spending an exorbitant sum on shielding.

 

[atrowe]

Wrap your computer up in aluminum foil.

 

[MillionaireNextDoor]

err.. interesting solution but RF will easily go through foil. Try maybe 5 feet of concrete on all sides

 

[JerryM]

I would expect a metal computer case to be a reasonably good RFI shield. However, all those wires coming out of it could be acting as antennas and radiating RF generated by your power supply. If you're pretty sure it's the power supply that's creating the RFI you could try to cut down on the amount getting out by clipping ferrite cores over the cables at the computer end. Radio Shack sells something called Snap-Together Toroid Choke Cores that might work to lower the amount of RF radiated.

Jerry