Ethernet cable causes RF interference?

Question

Ethernet cable causes RF interference?

I have an AE that won't output audio w/o a church radio station on top of the Airtunes. It's really loud in comparison to the Airtunes signal, but when I unplug the ethernet cable the interference goes away. That's great and all, but I don't really like having a router that can't connect to my cable modem. 🙂 Interference robustness doesn't do anything. Neither does changing channels. Any suggestions? I'm also using a generic Comcast-provided Motorola cable modem. Thanks for any help.

PowerBook G4, 1.67 gHz, 1GB RAM Mac OS X (10.4.5)

Posted on Mar 12, 2006 3:10 AM

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Answer 1

Mar 12, 2006 1:41 PM in response to Brian_Rowland

You can possibly eliminate the problem with a ground loop isolator on the audio path (between the Express and the speakers). Radio Shack sells them and has a lenient return policy if it doesn't work. The other alternative is to use an optical connection if feasible.

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Answer 2

Mar 13, 2006 3:14 AM in response to Brian_Rowland

Brian,

Although Alan understands your problem exactly, I can't seem to get it. The ethernet cable is unplugged from where ? the AE unit ? and it runs alongside which other cables ? the audio cable from the AE to the stereo ? Is the audio cable high-quality shielded ? I spent that little bit extra on mine as it was going to be running alongside power cables and past one speaker, and I get scarily good sound.

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Answer 3

Mar 13, 2006 8:59 PM in response to Brian_Rowland

Well, I first suspected that it was a ground problem and started unpluging the power from anything else I had plugged into the same power strip as the AE and clearing other cables out of the way. But then I unplugged the ethernet from the modem to get to another power cable and the radio station disappeared. It doesn't matter where it's unplugged from, just as long as the modem is not connected to the router. This tells me it's not RF interference on the audio cable, cause it sounds fine once the ethernet is out. I wouldn't think Apple would have the audio out and ethernet in connected or unshielded enough to cause this kind of problem, but maybe not. I will try the ground loop isolator cause it can't hurt, but I really think it's something inside the AE or modem. And unfortunately optical is not an option.
I will let you know what the ground loop isolator does. And thanks to both of you for responding.
-Brian

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Answer 4

Mar 13, 2006 9:07 PM in response to Brian_Rowland

.

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Answer 5

Mar 29, 2006 8:59 PM in response to Alan Somers

An update for anyone searching the threads.
The problem was not with the AE, or the modem. It was the cable...uh, cable.
I wrapped a high quality copper audio cable around the threaded ring that should be the ground for the cable signal and the attached it to a ground pin on one of the other things plugged into my power strip. Noise gone. Comcast (and their installers) suck.
Thanks everyone, for the advice.

PowerBook G4, 1.67 gHz, 1GB RAM Mac OS X (10.4.2)

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Answer 6

Mar 30, 2006 8:13 AM in response to Brian_Rowland

Brian,

thanks for posting back with that. I have no idea what goes into a "cable" cable, but I'm amazed it can cause so much interference. This may help a lot of others.

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Answer 7

Apr 1, 2006 10:39 AM in response to Brian_Rowland

Could you please explain exactly what kind of cable you bought and used and what exactly you wrapped it around to? More steps would probably be helpful too. I'm getting the same kind of radio noise which is interfering w/ my Mighty Mouse and my external speakers. I suspect it had to do with the coaxial wall outlet but I no longer have Comcast and I'm sure their installers did a not-so-elegant job grounding stuff properly in the first place.

Thanks!

Power Mac G5 dual-core 2.3GHz, 15" PowerBook G4 1.5GHz, 60GB iPod (with video) Mac OS X (10.4.5) 20" Apple Cinema Display

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