FM radio interference from Opus 150

**cMags** · 05-01-2006, 03:58 PM

I've got a Shuttle PC in the trunk of my Subaru Outback Sport, with an Opus 150W DCX2.1215.XPC. I've got an in-glass antenna in the tailgate, which is about 3' from the power supply.

Before I got the Opus, I was using the standard PSU and an inverter. I didn't have the problems I have now. Now anytime the PC is plugged in (worse when on, but still bad when off), I get crappy radio reception. This morning I was stopped and had absolutely no radio reception, but when I unplugged the Opus, reception was clear as day.

Has anyone had this issue before? Any ideas? The Shuttle shouldn't be leaking much EMI out of the case, so I've got to assume that the noise is radiating back out the power line (unshielded, standard automotive 10-gauge). I'm going to try a ferrite bead on the line, but I'm open to suggestions.

**cMags** · 05-05-2006, 09:30 AM

Nobody's ever had any radio interference from their car PC?

I can't be the only one.

**zootjeff** · 05-05-2006, 10:13 AM

Originally Posted by cMags

Nobody's ever had any radio interference from their car PC?

I can't be the only one.

The best thing to do is make a metal box for it and ground it to the board. You can also try putting an inductor at the input. A 2-10uh that can handle 10-20 amps would be ideal, as close to the power supply as possible. The other option is a ferrite shield, or choke.

-Jeff

**cMags** · 05-05-2006, 10:37 AM

Thanks for the input, Jeff.

I tried a ferrite clamp on the power line, with one turn of wire around it, to no avail. I'm going to try putting a portable radio in my car to see if its also affected. I'm also going to try powering the PC from a jumper cable from another 12V source (funny to think about needing a jump from another car for the PC hehehe). Hopefully one of these will tell me whether I've got a radiated or conducted noise problem.

a metal cage/box is going to be a pain to build as just a test, maybe I can find someone with a birdcage or something to borrow just to try it out. I suppose I could try taping up all the edges of the PC with copper tape, but again, this is quite a pain.

Does anyone know what kind of filtering the Opus 150 has on the power input? It seems like my problem may be with stand-by power, since the problem doesn't get better/worse depending on whether the PC is on/off, but completely goes away if I unplug the PSU.

Again, I'm one of the few people who actually leave the PC's guts in a metal case (I've seen many installs in plexiglass cases, or no cases at all), and I can't seem to find any info on anyone else having RF interference problems. Why do I get to be so lucky?