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Desktop metal shielded PC case?
I'm looking for a solid desktop (either pizza-box or mini-tower)
computer case that has an all-metal exterior for shielding RFI. This is for use around radios etc. I realize that SVGA monitors, mice, and keyboard leak too, but right now I'm looking mainly at the PC box. Most of the cheaper cases come pretty close to good shielding, but they have these plastic filler panels in the drive bays that offer no shielding and let a lot of RF leak out. Most of the fancier cases in the computer stores around here have humongous plastic pieces on the side. I'm looking for all-metal. Rack-mount server cases seem to be pretty good in terms of metal shielding all around but I need something for desktop use. Any suggestions? If all else fails I can just put some perforated metal over the holes in a cheap case, but I'd rather just buy a good case to begin with. Tim. |
They make 'em:
http://www.directron.com/pc75.html I have even seen an all stainless steel case which is used around food production plants... can't find anything close with google though... Son has an all aluminum case, $175.00 is what he paid for it!--OUCH!!!! Warmest regards, John -- If "God"--expecting an angel... if evolution--expecting an alien... just wondering if I will be able to tell the difference! wrote in message oups.com... | I'm looking for a solid desktop (either pizza-box or mini-tower) | computer case that has an all-metal exterior for shielding RFI. This | is for use around radios etc. I realize that SVGA monitors, mice, and | keyboard leak too, but right now I'm looking mainly at the PC box. | | Most of the cheaper cases come pretty close to good shielding, but they | have these plastic filler panels in the drive bays that offer no | shielding and let a lot of RF leak out. | | Most of the fancier cases in the computer stores around here have | humongous plastic pieces on the side. I'm looking for all-metal. | | Rack-mount server cases seem to be pretty good in terms of metal | shielding all around but I need something for desktop use. | | Any suggestions? If all else fails I can just put some perforated | metal over the holes in a cheap case, but I'd rather just buy a good | case to begin with. | | Tim. | |
You could always shield the plastic panels with copper or aluminum foil or
screen--etc... (on the inside--out of sight) Warmest regards, John -- If "God"--expecting an angel... if evolution--expecting an alien... just wondering if I will be able to tell the difference! "John Smith" wrote in message ... | They make 'em: | http://www.directron.com/pc75.html | | I have even seen an all stainless steel case which is used around food | production plants... can't find anything close with google though... | | Son has an all aluminum case, $175.00 is what he paid for it!--OUCH!!!! | | Warmest regards, | John | -- | If "God"--expecting an angel... if evolution--expecting an alien... just | wondering if I will be able to tell the difference! | | wrote in message | oups.com... || I'm looking for a solid desktop (either pizza-box or mini-tower) || computer case that has an all-metal exterior for shielding RFI. This || is for use around radios etc. I realize that SVGA monitors, mice, and || keyboard leak too, but right now I'm looking mainly at the PC box. || || Most of the cheaper cases come pretty close to good shielding, but they || have these plastic filler panels in the drive bays that offer no || shielding and let a lot of RF leak out. || || Most of the fancier cases in the computer stores around here have || humongous plastic pieces on the side. I'm looking for all-metal. || || Rack-mount server cases seem to be pretty good in terms of metal || shielding all around but I need something for desktop use. || || Any suggestions? If all else fails I can just put some perforated || metal over the holes in a cheap case, but I'd rather just buy a good || case to begin with. || || Tim. || | | |
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They make 'em: http://www.directron.com/pc75.html
What about that gaping big square-foot hole in the side? I have even seen an all stainless steel case which is used around food The old "PC Power and Cooling" all-metal-tower used to be good (I think it was available in chrome!), but they don't sell them anymore (probably because they cost several hundred $). I'm not looking for anything particularly stylish. Just a case without big holes covered by plastic. Tim. |
Personally, I'd place a sheet of aluminum window screen between the acrylic
sheet and the case--that way I could still get the effect of looking into the case, and still be shielded... Other than that, I'd pick the one from their catalog which DOESN'T have the "big gaping hole" in the side... grin Warmest regards, John -- If "God"--expecting an angel... if evolution--expecting an alien... just wondering if I will be able to tell the difference! "Tim Shoppa" wrote in message oups.com... | They make 'em: http://www.directron.com/pc75.html | | What about that gaping big square-foot hole in the side? | | I have even seen an all stainless steel case which is used around | food | | The old "PC Power and Cooling" all-metal-tower used to be good (I think | it was available in chrome!), but they don't sell them anymore | (probably because they cost several hundred $). | | I'm not looking for anything particularly stylish. Just a case without | big holes covered by plastic. | | Tim. | |
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My 3.3Ghz seems to broadcast on most frequencies--from rfi in the am radio,
fm radio, sw bands, etc... toroid chokes on the phone/modem/net card cables helps a lot... Warmest regards, John -- If "God"--expecting an angel... if evolution--expecting an alien... just wondering if I will be able to tell the difference! "Jeremy Boden" wrote in message ... | In message .com, | writes | I'm looking for a solid desktop (either pizza-box or mini-tower) | computer case that has an all-metal exterior for shielding RFI. This | is for use around radios etc. I realize that SVGA monitors, mice, and | keyboard leak too, but right now I'm looking mainly at the PC box. | | Most of the cheaper cases come pretty close to good shielding, but they | have these plastic filler panels in the drive bays that offer no | shielding and let a lot of RF leak out. | | Most of the fancier cases in the computer stores around here have | humongous plastic pieces on the side. I'm looking for all-metal. | | Rack-mount server cases seem to be pretty good in terms of metal | shielding all around but I need something for desktop use. | | Any suggestions? If all else fails I can just put some perforated | metal over the holes in a cheap case, but I'd rather just buy a good | case to begin with. | | Tim. | | What band does a PC broadcast on? | | -- | Jeremy Boden |
In (rec.radio.amateur.homebrew), Michael A. Terrell wrote:
Jeremy Boden wrote: In message .com, writes I'm looking for a solid desktop (either pizza-box or mini-tower) computer case that has an all-metal exterior for shielding RFI. This is for use around radios etc. I realize that SVGA monitors, mice, and keyboard leak too, but right now I'm looking mainly at the PC box. Most of the cheaper cases come pretty close to good shielding, but they have these plastic filler panels in the drive bays that offer no shielding and let a lot of RF leak out. Most of the fancier cases in the computer stores around here have humongous plastic pieces on the side. I'm looking for all-metal. Rack-mount server cases seem to be pretty good in terms of metal shielding all around but I need something for desktop use. Any suggestions? If all else fails I can just put some perforated metal over the holes in a cheap case, but I'd rather just buy a good case to begin with. Tim. What band does a PC broadcast on? -- Jeremy Boden It depends on the computer. What he said. Usually on all harmonics of each clock in the box, from ~1.8 MHz on up to near daylight -- or at least well past 70 cm., in the case of the boxes here at home and at work. Add in all their cross-modulation products as well, and it starts to look pretty gross. One of these days I'll borrow a spectrum analyzer and see what's coming from where. I know that the bedroom TV puts out a lot of stuff around 3.5-4.0 MHz. and the cable box is pretty noisy, too. Hard to hear DX over all the in-house QRM. -- Mike Andrews W5EGO 5WPM Extra Tired old sysadmin working on his code speed |
Take a closer look at some of the higher quality cases.
All the cases I have purchased within the past few years have plastic, as you say, over the drive bays, but there is metal behind that plastic. If you want to use the bay you need to pop out the metal. Except for floppies, the drives generally have metal behind their plastic faces, too. More important is the scheme for attaching the sides. Those little drive holes will let some RF out, but long, narrow gaps in the side let out a lot more. Most recent cases seem to have fairly elaborate schemes to be sure that the sides don't leak. I can't believe many of the mass marketed cases actually make it to manufacturers who need to be certified, but the lengths they go to ensuring RF shielding lately would indicate to me they are getting pressure from somewhere. As best I can tell, the case isn't nearly the problem the wires are, but even there, it seems like the newer stuff is pretty well behaved. My radios are pracically surrounded by computers and no noise anymore. Used to be a real problem but as the computer equipment has gotten newer, the interference problems have faded. I can still hear my Ethernet on some bands, but I have a pretty ancient hub. Once that gets replaced I suspect the ethernet problem will disappear, too. ... |
xpyttl wrote:
Don't forget to throw some toroids on your cabling. I have a whole bunch of 2" cores I keep around just this purpose. My wifes machine threw out a lot of QRM. Cheap case and power supply (though all-metal). Wrapped the cord twice around a core and poof! QRM gone. -- Visit the new Unlicensed QRP website and forums: http://www.qrp.timpauly.com The site and forums are geared toward legal, unlicensed (non-ham) radio operation for low-power hobbyists around the world. |
On Sun, 15 May 2005 12:28:21 -0700, "John Smith"
wrote: Personally, I'd place a sheet of aluminum window screen between the acrylic sheet and the case--that way I could still get the effect of looking into the case, and still be shielded... Other than that, I'd pick the one from their catalog which DOESN'T have the "big gaping hole" in the side... grin FYI: Some plastic used in cases has a "flash" coating of aluminum (sputtered in a vacuum chamber). While the metal is extremely thin, just a few microns, it is enough to provide RFI shielding. Obviously not as good as solid metal for shielding, but good enough for many uses. Check out what sort of plastic before assuming it will not shield. Happy trails, Gary (net.yogi.bear) -- At the 51st percentile of ursine intelligence Gary D. Schwartz, Needham, MA, USA Please reply to: garyDOTschwartzATpoboxDOTcom |
In article .com,
Tim Shoppa wrote: They make 'em: http://www.directron.com/pc75.html What about that gaping big square-foot hole in the side? I have even seen an all stainless steel case which is used around food The old "PC Power and Cooling" all-metal-tower used to be good (I think it was available in chrome!), but they don't sell them anymore (probably because they cost several hundred $). I'm not looking for anything particularly stylish. Just a case without big holes covered by plastic. Tim. If you buy a brand name computer it meets some prety good FCC specs for emission. IMO if you are carefull any good all-metal case will produce an EMI-tight case. -- a d y k e s @ p a n i x . c o m Don't blame me. I voted for Gore. |
) writes: I'm looking for a solid desktop (either pizza-box or mini-tower) computer case that has an all-metal exterior for shielding RFI. This is for use around radios etc. I realize that SVGA monitors, mice, and keyboard leak too, but right now I'm looking mainly at the PC box. Have you considered trying an old used HP computer case, one that was used by government? My Linux box is an HP Kayak XA (Pentium II 350 MHz) that has a Tempest-certified case. It was used by the Canadian government for classified work and it was part of a lot that I bought from Crown Assets Disposal. I expect that anything similar would satisfy your needs. (My Linux box does't need all that shielding but why bother changing it?!) .... Martin VE3OAT |
xpyttl wrote:
[Good hints about where to look for shielded cases, esp. related to FCC standards] [...] the case isn't nearly the problem the wires are This is very true. A typical SVGA copper cable puts out all sorts of hash (as well as the monitor!). And lotsa junk is radiated and conducted out by the power supply cable, even for the "best of the best" PC clone supplies. I've discovered and/or engineered some workarounds, consisting of going to optical fiber instead of metal whenever possible. But my converters are usually outside the PC case so this doesn't completely eliminate the radiation from copper cabling. I'm starting to think I should just sit inside the Faraday cage with my computer, and put all the radios outside! Tim. |
In article .com,
Tim Shoppa wrote: xpyttl wrote: [Good hints about where to look for shielded cases, esp. related to FCC standards] [...] the case isn't nearly the problem the wires are This is very true. A typical SVGA copper cable puts out all sorts of hash (as well as the monitor!). And lotsa junk is radiated and conducted out by the power supply cable, even for the "best of the best" PC clone supplies. I've discovered and/or engineered some workarounds, consisting of going to optical fiber instead of metal whenever possible. But my converters are usually outside the PC case so this doesn't completely eliminate the radiation from copper cabling. I'm starting to think I should just sit inside the Faraday cage with my computer, and put all the radios outside! Tim. They "lumps" found on many power and data cables are ferrite cores that attenuate the RF hash that leakes out on the conductors. Building an RF-proof case is trivial if you don't need any peripherals. RF comes out on the wires. Look at a copy of the Ham Radio _The ARRL Handbook for Radio Communications_, in any decent library or bookstore. They cover RFI solutions. Do you have an EMI problem ? -- a d y k e s @ p a n i x . c o m Don't blame me. I voted for Gore. |
In message .com, Tim
Shoppa writes xpyttl wrote: [Good hints about where to look for shielded cases, esp. related to FCC standards] [...] the case isn't nearly the problem the wires are This is very true. A typical SVGA copper cable puts out all sorts of hash (as well as the monitor!). And lotsa junk is radiated and conducted out by the power supply cable, even for the "best of the best" PC clone supplies. I've discovered and/or engineered some workarounds, consisting of going to optical fiber instead of metal whenever possible. But my converters are usually outside the PC case so this doesn't completely eliminate the radiation from copper cabling. I'm starting to think I should just sit inside the Faraday cage with my computer, and put all the radios outside! Tim. Have you tried unplugging the PC from the mains? -- Jeremy Boden |
Tim Shoppa wrote: xpyttl wrote: [Good hints about where to look for shielded cases, esp. related to FCC standards] [...] the case isn't nearly the problem the wires are This is very true. A typical SVGA copper cable puts out all sorts of hash (as well as the monitor!). And lotsa junk is radiated and conducted out by the power supply cable, even for the "best of the best" PC clone supplies. I've discovered and/or engineered some workarounds, consisting of going to optical fiber instead of metal whenever possible. But my converters are usually outside the PC case so this doesn't completely eliminate the radiation from copper cabling. I'm starting to think I should just sit inside the Faraday cage with my computer, and put all the radios outside! Tim. Tim, You are really close to your own answer. I built a Faraday cage area around my laptop. And also plugged into a surge/noise filter for the AC and use metal hood cables to hook up to the radios. I hardly experience any noise at all. The reason is most manufacturer are turning to plastics and putting less and less shielding in them. Keep in mind the OEM's are building for the general public. Bruce |
Jeremy Boden wrote:
What band does a PC broadcast on? It leaks on wide range, with peaks varying on different PC's. You can certainly hear it clearly enough bringing an AM radio near your computer. |
wrote in message oups.com... I'm looking for a solid desktop (either pizza-box or mini-tower) computer case that has an all-metal exterior for shielding RFI. This is for use around radios etc. I realize that SVGA monitors, mice, and keyboard leak too, but right now I'm looking mainly at the PC box. Most of the cheaper cases come pretty close to good shielding, but they have these plastic filler panels in the drive bays that offer no shielding and let a lot of RF leak out. Most of the fancier cases in the computer stores around here have humongous plastic pieces on the side. I'm looking for all-metal. Rack-mount server cases seem to be pretty good in terms of metal shielding all around but I need something for desktop use. Any suggestions? If all else fails I can just put some perforated metal over the holes in a cheap case, but I'd rather just buy a good case to begin with. All the cases I have bought have a metal insert that mounts behind the plastic front piece. If that isn't there a simple piece of aluminum screen wire could be cut and fit on the back side of the drive bay. |
Tim.. Having dabbled around in this noisy rf environment for about 20 years..the following things will help: 1. The Antec Sonata is a good starting point as far as cases go. 2. Get away from the noise of the convential CRT monitor! Check on a good Flat panel from NEC or Samsung and many others. Study up on the FCC type shielding they adhere to...usually Canada, Japan Korea and others. Usually they are represented by the series of stickers of authenication as to rf rules they adhere to. This has improved over time. Also, some old video cards have a lot of rf type noise. If you have an older sound card, many of them have digital/analogue converters that sing with noise and Rf. Be extremely awsare of any "switching power supplies" these are a nightmare, generally, in a radio environment. Stay away from these supplies..confirm that it is not a switching supply. Also, the battery back up power supply has the same problem in a radio environment...they emit unbearable noise on most radios..particularly on the 80/75 meter bands. Put your PCI card slot metal shields in where you've removed the PCI card. Also, most of the good cases, including the Antec, have some RF shields..I've never proven to myself if these work or not..however, these in theory help maintain a lot of RF energy from escaping from the above mentioned components..however, it is best to get a better built component that does not radiate much RF. Make sure the radio is removed from the PC area as far as possible...also note the reduction in noise at different angles from the PC. Mind you, an old CRT monitor will wipe you out with noise. A small palm held am radio put next to a pc will help find out which component is offending you. Note also, on difficult situations, there are all types of shielding material. Don't overlook your AC power and noise brought in on the lines. Some power filtering supplies from some cable suppliers will help. Good luck, Leonard... P.S some cheap fans cause electrical noise. Again pc positioning is critical. Google on rf shielding material On Sun, 15 May 2005 11:00:57 -0700, shoppa wrote: I'm looking for a solid desktop (either pizza-box or mini-tower) computer case that has an all-metal exterior for shielding RFI. This is for use around radios etc. I realize that SVGA monitors, mice, and keyboard leak too, but right now I'm looking mainly at the PC box. Most of the cheaper cases come pretty close to good shielding, but they have these plastic filler panels in the drive bays that offer no shielding and let a lot of RF leak out. Most of the fancier cases in the computer stores around here have humongous plastic pieces on the side. I'm looking for all-metal. Rack-mount server cases seem to be pretty good in terms of metal shielding all around but I need something for desktop use. Any suggestions? If all else fails I can just put some perforated metal over the holes in a cheap case, but I'd rather just buy a good case to begin with. Tim. |
In article ,
lcw999 wrote: Tim.. Having dabbled around in this noisy rf environment for about 20 years..the following things will help: 1. The Antec Sonata is a good starting point as far as cases go. 2. Get away from the noise of the convential CRT monitor! Check on a good Flat panel from NEC or Samsung and many others. Study up on the FCC type shielding they adhere to...usually Canada, Japan Korea and others. Usually they are represented by the series of stickers of authenication as to rf rules they adhere to. This has improved over time. Also, some old video cards have a lot of rf type noise. If you have an older sound card, many of them have digital/analogue converters that sing with noise and Rf. Be extremely awsare of any "switching power supplies" these are a nightmare, generally, in a radio environment. Stay away from these supplies..confirm that it is not a switching supply. All PC power supplies are of the switching type. A laptop running on it's batteries may be the quietest out-of-the-box system. A "KVM" (remote "keyboard/video/mouse") box will allow you to put your PC many feet away from your radio. Use this with an LCD screen. Some models are he http://makeashorterlink.com/?E27C22D1B -- a d y k e s @ p a n i x . c o m Don't blame me. I voted for Gore. |
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Be extremely awsare of any "switching power supplies"
these are a nightmare, generally, in a radio environment. Stay away from these supplies..confirm that it is not a switching supply. ------- Professional receivers like the ones from Watkins -Johnson have internal (obviously high quality) SMPS Also, the battery back up power supply has the same problem in a radio environment...they emit unbearable noise on most radios..particularly on the 80/75 meter bands. ------------------------------------- I have an APC - Back-UPS PRO650 less than a metre away from my TenTec transceiver and do NOT suffer from noise on any band ,because of this UPS (which is always on -line). Frank GM0CSZ / KN6WH |
I have an APC - Back-UPS PRO650 less than a metre away from my TenTec
transceiver and do NOT suffer from noise on any band ,because of this UPS (which is always on -line). ************************************************** ********************** i use 2 of the APC CS 500. lot of noise. i wraped both in alu-screening. and grounded both to third pin on the mains. cleared up that noise. and, if you use a router, check out the d-link- DI604. i used a link-sys for too many years. they were cheap and easy to set up. tried all the known name routers. ended up with the d-link DI-604. no noise at all. i have a friend who's a manager for compUSA, and she let me try a bunch. this is wired, i didn't try the wireless units... good luck/ just my 2 cents... Drifter... |
On Sun, 15 May 2005 20:08:27 +0100, Jeremy Boden
wrote: What band does a PC broadcast on? My laptop screws up my HT on two frequencies in the VHF band. I have to be at least 20 or 30 feet away before the hiss goes away. The same hiss is still present when the laptop is unplugged so it's not the power adapter. Tony |
On 15 May 2005 11:00:57 -0700, wrote:
I'm looking for a solid desktop (either pizza-box or mini-tower) computer case that has an all-metal exterior for shielding RFI. This is for use around radios etc. I realize that SVGA monitors, mice, and keyboard leak too, but right now I'm looking mainly at the PC box. I haven't seen a case that wasn't metal. Some/most have plastic fronts over the metal. Most of the cheaper cases come pretty close to good shielding, but they have these plastic filler panels in the drive bays that offer no shielding and let a lot of RF leak out. As do the expensive ones as well. The $30 - $40 ones I've used had metal pieces that had to be removed from the 5 1/4" bays to use them. Unfortunately when in use the drives have plastic fronts even if they do have a metal chassis. Most of the fancier cases in the computer stores around here have humongous plastic pieces on the side. I'm looking for all-metal. Standard is metal, fancy is a plastic insert with metal cross pieces and a lighted fan for effects. Surprisingly, those come with metal covers over the drive bays behind the plastic ones in the front panel. Rack-mount server cases seem to be pretty good in terms of metal shielding all around but I need something for desktop use. Any suggestions? If all else fails I can just put some perforated metal over the holes in a cheap case, but I'd rather just buy a good case to begin with. Find a local computer store and look at the cases they handle. Look them over and find which ones have the metal pieces over the drive bays. They aren't inserts, they are actually part of the front stamping and have to be broken out. Sorta like knockouts in electrical boxes. However, I doubt you will find much relief even with a full metal case. I built up all 4 computers we use here using standard parts. Now, I have one of those with the plastic insert on the side setting about a foot and a half below my rigs (Icom 756 Pro, Alpha 76A, Alinco DR610T, and Kenwood TMV7A. The computer is an MSI K7N2Delta Platinum with a 3.2 Gig Athlon, 1 Gig 400 MHz CAS-2 DDR Ram, 400 Gig SATA RAID, and three EIDE 7200 RPM HDs totaling 920 Gig. The monitor (19" CRT)sets directly above the two duobanders. About three feet to the left is this computer which is the standard all metal case with an MSI K8N Neo Series with a 3.4 Gig 64-bit Athlon, 2 Gig 400 MHz Dual, DDR RAM.and about 650 Gig of HD space. (I don't have the SATA RAID installed yet.) The monitor is a 17" NEC 1760v. Each computer is on its own UPS. All have the dual layer, high speed DVD R/W drives and are part of a gigabit network that has two more computers. There is a 5 port gigabit switch, router, and cable modem less than two feet to the left of the duobanders and just over three feet from the HF rig. (I also run the legal limit from 160 through 10) I have no detectable interaction between the rigs and the computer system in the house. The one in the shop will break the squelch if you put the HT next to the case, or hold the antenna for the best pick up, out to about 3') I just brought the HT (VX-7R) in and the squelch did not open even when touching the antenna to the individual computer cases. I should add that right now the network is running near capacity with backups across the network and several large downloads from the cable modem. My wife's computer is about 15 feet to the south (in another room) and I do not hear it with the HT in there. The one is the shop is at the end of about 115 feet of Cat-5e and I use the HT within a foot of the monitor. That one is only a 2 Gig Athlon, but it too has 620Gig of HD space and a 19" CRT monitor. Those too are MSI motherboards with my wife's being a K7N2 Delta series and 2.8 Gig Athlon. I've forgotten the model of the one in the shop, but it's the oldest of the four. BTW, that case is also one of those with the plastic side windows and lighted fan.:-)) Whether it's the motherboards, the cases, grounding, or a combination, I don't know, but interference has not been a problem...unless you count the electric fence across the road. Why I can not pick up the computers at all in here, but can open the squelch out to about 3' from the computer in the shop under ideal conditions I have no idea. I think it's more of a crap shoot. Some high end systems bother as bad as some low end systems while some low end systems cause no problems. All four computers run 24 X 7. Roger Halstead (K8RI & ARRL life member) (N833R, S# CD-2 Worlds oldest Debonair) www.rogerhalstead.com Tim. |
On 16 May 2005 01:13:01 GMT, (Martin Potter)
wrote: ) writes: I'm looking for a solid desktop (either pizza-box or mini-tower) computer case that has an all-metal exterior for shielding RFI. This is for use around radios etc. I realize that SVGA monitors, mice, and keyboard leak too, but right now I'm looking mainly at the PC box. Have you considered trying an old used HP computer case, one that was used by government? My Linux box is an HP Kayak XA (Pentium II 350 MHz) that Most of the new boxes are very well shielded with knockouts in the drive bays. . Roger Halstead (K8RI & ARRL life member) (N833R, S# CD-2 Worlds oldest Debonair) www.rogerhalstead.com has a Tempest-certified case. It was used by the Canadian government for classified work and it was part of a lot that I bought from Crown Assets Disposal. I expect that anything similar would satisfy your needs. (My Linux box does't need all that shielding but why bother changing it?!) ... Martin VE3OAT |
writes: I'm looking for a solid desktop (either pizza-box or mini-tower) computer case that has an all-metal exterior for shielding RFI. This is for use around radios etc. I realize that SVGA monitors, mice, and keyboard leak too, but right now I'm looking mainly at the PC box. I know this is an old thread, but I have a related question: Quite a few people are building their own PC cases these days-- for example, http://www.mini-itx.com (follow the links on the right side of the page). As far as I can see, none of these has *any* RF shielding at all. And I have yet to hear of them causing any problems (these are not ham radio operators). The only RF problems I've heard of recently (with consumer electronics) are microwave ovens interfering with some kinds of cordless phones. I'm thinking maybe the only kind of RFI "the masses" are worried about is TV, and they all have cable... So I'm thinking of building a computer case for a specific use, and I'm wondering if I should bother to worry about shielding (evidence suggests maybe not). My first thought was aluminum foil, but aluminum forms a non-conductive oxide, and I don't know if it would ground reliably (not to mention the "tinfoil hat" jokes). My second thought was copper foil from http://www.onlinemetals.com (around $.98/sq ft, but shipping adds quite a bit). Any comments? PS: I like this one: http://www.mini-itx.com/projects/cardboardcube/ |
In article ,
Ron Bean wrote: writes: I'm looking for a solid desktop (either pizza-box or mini-tower) computer case that has an all-metal exterior for shielding RFI. This is for use around radios etc. I realize that SVGA monitors, mice, and keyboard leak too, but right now I'm looking mainly at the PC box. I know this is an old thread, but I have a related question: Quite a few people are building their own PC cases these days-- for example, http://www.mini-itx.com (follow the links on the right side of the page). As far as I can see, none of these has *any* RF shielding at all. And I have yet to hear of them causing any problems (these are not ham radio operators). The only RF problems I've heard of recently (with consumer electronics) are microwave ovens interfering with some kinds of cordless phones. I'm thinking maybe the only kind of RFI "the masses" are worried about is TV, and they all have cable... So I'm thinking of building a computer case for a specific use, and I'm wondering if I should bother to worry about shielding (evidence suggests maybe not). What are you worried about? Ham and short wave fans have a legit issue, and I guess people doing *very* high quality audio do also. If you don't fit in a special catagory try taking the top of a standard PC and hold an AM and an FM radio right next to the running PC and listen for the noise. You won't hear much. Try it again with the lid on. PC cases are built to FCC and European specs for radio emissions. They are fairly tightly sealed. The vast amount of emmisions that *do* come out go over all the wires connected to the PC. Pick up an ARRL handboox about sheilding and RF interferance if you want to learn more. http://www.arrl.org/ -- a d y k e s @ p a n i x . c o m Don't blame me. I voted for Gore. |
Just get one of the name brand pc's from a yard sale, or thrift shop. These cases have paint inside that helps stop the emi from getting out. Good quality cables are also a must. case_dude |
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case_dude writes: Just get one of the name brand pc's from a yard sale, or thrift shop. These cases have paint inside that helps stop the emi from getting out. I would have no problem spending money on a commercially made case, if I could find one I liked. IMHO, they all suck. Flashy plastic and poor access even with all the covers off (I didn't consider rackmount cases because I'd like it to be semi-portable). I do have one "beige box" here, but I seldom open that one, so I don't care how awkward it is to mount stuff in it. The other one I frequently swap out components and I want one that gives me better access with the covers off. I'm considering a "semi-monocoque" design with no frame. |
I worked for weeks to get the RFI out of my computer. It was coming
from within a commerical RFI protected case. I had S-9 plus readings on 40 and 80 meters. When I finally turned my attention to AC power cord and filtered it, levels dropped into the normal band noise. win w0lz |
Ron Bean wrote:
I'm not worried about anything specific, but I know the manufacturers go to great lengths to pass an rfi test, and yet it seems they are solving a non-problem. I do occasionally run PCs with the covers off, but I seldom have a radio or TV on, so if I were causing any interference anywhere (eg in the apartment nextdoor) I wouldn't notice it. I've heard urban legends about early microcomputers causing interference, were they noisier or were old TVs more sensitive to it? Early PCs had a lower frequency system clock so there were more harmonics to beat against other signals to cause interference. The original IBM PC had a 4.77 MHz system clock that caused all kinds of problems. There wasn't' a TV channel that didn't have at least one harmonic, and some had two. The interference dropped off as the frequency went up, but some early computers could wipe out the upper UHF TV channels. -- Link to my "Computers for disabled Veterans" project website deleted after threats were telephoned to my church. Michael A. Terrell Central Florida |
Many of the pc power supplies used in the clones
have minimal or no filtering inside them, once they get the contracts, they strip them down, eliminate filters and add jumpers to them. Win wrote: I worked for weeks to get the RFI out of my computer. It was coming from within a commerical RFI protected case. I had S-9 plus readings on 40 and 80 meters. When I finally turned my attention to AC power cord and filtered it, levels dropped into the normal band noise. win w0lz |
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