Getting a good RF shield is a tricky affair. My company has spent considerable time working with these issues. As far as a radio wave is concerned, a very thin slot is just about as big an opening as a big hole. Think gaps around doors and drives. At one gHz you are trying to prevent any opening larger than ~ 1 centimeter. Them little copper finger seals thingies and interlocking joints really do a pretty good jog of keeping your computer off the air. Considering the difficulties, I am surprised with how well cheap cases do work. Usually not as good as they should, but better than you are likely to do on your own. I am leaning towards putting a regular case inside something else. Don't forget good cooling; excessive heat is a significant factor in reduced reliability and life. Mark Browne ----- Original Message ----- From: "Kelly Black" <kelly-black at mediaone.net> To: <tclug-list at mn-linux.org> Sent: Tuesday, January 15, 2002 6:17 AM Subject: Re: [TCLUG] Static electricity (and an offer to buy) Cant speak to the U of M's setup, but at UND they just lined the whole room with fine wire mesh. I suppose you could line the inside of a wood cabinet with a wire mesh to get an effective Faraday cage, but you should be carefull to not have the MB touch it in and have it short out the power and ground rails. The aluminum spray idea also seemed to be a good way to go, although I don't know where you find it. Kelly Black KB0GBJ On Monday 14 January 2002 09:01, you wrote: > On Mon, Jan 14, 2002 at 08:05:54AM -0600, Jared Burns wrote: > > You machine will emit RF (radio frequency) radiation at the > > frequency of your machine's clock frequency (100kHz, 133kHz, etc.). > > Boy, I wish it were that simple. And the clock freqs you list don't > make a lot of sense. > > The trouble is that for one, you have more than one frequency in the > machine -- what about the video outs? What about clock dividers / > multipliers? > > The other problem is that we like nice mostly square pulses, but that > means boatloads of harmonics -- IIRC a single Dirac pulse function is > energy at all freqs. Anyway, the upshot is that both harmonics and > sub-harmonics are generated in scads, so your radiated spectra is > anything but clean. > > (Kelly or any other Hams -- keep me honest here.) > > For that matter, you're violating some FCC rules/laws if you let these > kind of emissions out, but that doesn't mean they'd catch on. > > > Make sure you have the components inclosed in a Faraday cage or you > > and your neighbors will have a hard time picking up radio signals > > (at least around the frequency of your clock) while your machine is > > running. :) > > Speaking of Faraday cages, does anyone know what it is they do that > they needed to build one around the new Alumni center at the U? ;) _______________________________________________ Twin Cities Linux Users Group Mailing List - Minneapolis/St. Paul, Minnesota http://www.mn-linux.org tclug-list at mn-linux.org https://mailman.mn-linux.org/mailman/listinfo/tclug-list