Interference caused by ATI 550 Pro

[riles]

Edit: I realize that the title makes it look like I'm blaming the interference on the ATI card. I'm not. The card worked great in a normal tower. It was my cramming of components next to each other in a small footprint case that is causing the interference...
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Hi Guys. I have been using GBPVR for well over a year now, and love everything about it. Up until about 2 weeks ago, I was using an old Dell tower to do everything, and it all worked great

Recently, I decided to splurge and built a very small HTPC, using a Flex mobo and other small pieces, including a very small custom built case. Needless to say, everything is crammed in the case, with literally millimeters seperating the different parts.

Now, I am getting some interference on my cable signal. It only affects a few channels, and it isn't very severe. My concern is that it affects all tv's connected to my cable line.

Is there a way to isolate the interference so that only my PVR is affected? I'm thinking like a coax version of a diode? Would a ferrite clamp help?

I don't really care about a little interference on my recordings since I just watch the things on my iPod, but I don't want to see the lines on all of my tv's.

[JimF]

You could try an amplifier with its output connected to your HTPC. The TVs would then be connected to a splitter that feeds the input of the amplifier. That will provide some isolation to the HTPC, and introduce some loss going back to your other TVs. It will at least attenuate the interference, assuming that it originates with your HTPC.

One minor problem is that these days many amplifiers are designed to allow signals to feed from the output back to the input, in order to allow cable modems or signaling for video on demand to reach the cable company. That in effect reduces the isolation. The older amplifiers did not have that, and will provide more isolation. If you use a splitter amp, place 75 ohm dummy loads (resistors) on the unused outputs, to prevent the amplifier from becoming unstable, which will just produce more interference. Also, to increase the loss back to the TVs, you can put in an attenuator at the input of the amplifier. They used to sell 6 dB and 20 dB attenuators at Radio Shack in the U.S., but I don't know what they have anymore. In fact, if you have enough signal, you could just try the attenuators without the amplifier; it might work.

There is also an old trick of just coiling up 10 feet or so of the coax cable that feeds your HTPC into a loop maybe six inches in diameter. That eliminates some forms of interference which propagate along the outer shielding of the cable by introducing inductive reactance. It may take some experimenting to find what works.

[riles]

Thanks for the tips. I'll definitely try the coiled cable- cheap and easy.

If that doesn't work, I'll just have to run a dc-dc power supply with an external power brick. Heck, that would let me make the thing so much smaller anyway, so I could even consider it an "upgrade".