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Author Topic: Computer Tower Case - EMI/RFI  (Read 19088 times)
AA5WG
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Posts: 496




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« on: July 11, 2010, 07:12:05 PM »

Hi to all:
I am looking for a i7 930 computer with a tower case having very low EMI/RFI emissions.  Are there any solid recommendations on an outstanding EMI/RFI proof or nearly proof computer tower case?

Thank you to all.
73,
Chuck - AA5WG
Cedar, Michigan
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KQ6EA
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« Reply #1 on: July 14, 2010, 07:22:12 PM »

I like the Lian-Li cases without the side window. All aluminum construction, and very solid.
Newegg sells them at very good prices.
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KD4COX
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« Reply #2 on: July 15, 2010, 09:49:20 AM »

You MAY need to bond the panels together (I did, it helped a lot. Mine was a basic steel case though). Of course putting chokes on all the cables out helps quite a bit as well. I have 3 computers and can set my swr on top of any of them and get a readable signal on it's built in antenna now. The HF set through it's dipole can't tell if the computers are on or not.
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AA5WG
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« Reply #3 on: July 22, 2010, 05:54:10 AM »

KD4COX, KQ6EA and all:
Thank you for your ideas regarding computer cases.  I will look into this.  Anyone else have any suggestions regarding low EMI/RFI computer cases?
73,
Chuck - AA5WG
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KG0MN
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« Reply #4 on: August 04, 2010, 07:14:04 PM »

I run a computer hardware review web site and I can tell you from experience that Thermaltake cases have the best EMI shielding on the market. This will be found in their mid-priced cases and not the sub-100 dollar models. Most of them use a brass or copper finger strip that connects all side panels physically to the rest of the case. 
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AA5WG
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Posts: 496




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« Reply #5 on: August 06, 2010, 11:46:37 PM »

KG0MN:
Thank you for  your info. regarding computer cases and anti-EMI/RFI.
I will check into this company.
73,
Chuck - AA6WG
Cedar, Michigan
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LU2DFM
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Posts: 91




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« Reply #6 on: August 07, 2010, 06:17:23 AM »

Get and old good server from IBM, strip it and use the case. See that the case is complete with all the shield plugs for the disk bays unused; those plugs have large surface for good contact with the case.
The PSUs in that servers are very well filtered also.
You can get a complete working machine for less than the basic oriental case costs.
73
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AA5WG
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« Reply #7 on: August 16, 2010, 01:53:16 PM »

LU2DFM:
Thank you for your tip on computer cases.
73,
Chuck - AA5WG
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AA5WG
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Posts: 496




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« Reply #8 on: October 16, 2010, 06:09:29 AM »

Anyone else have any ideas?
Chuck
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KO7I
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Posts: 106




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« Reply #9 on: October 25, 2010, 04:11:53 PM »

Internal ribbon cable routing is a big deal. Avoid routing internal ribbon cables over the motherboard. The chips generate pretty strong EM fields and the cables can become passive antennas. Secure (tape) the ribbon cables down to the metal chassis of the pc case. These are tricks I have seen employed in the EMC test lab to reduce Radiated RF Emissions by a significant margin.
73 Don KO7i
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AA5WG
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« Reply #10 on: February 10, 2011, 05:40:13 PM »

Don:
Thank you.  Any other ideas?
Chuck
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KB4MB
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Posts: 295




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« Reply #11 on: February 11, 2011, 05:32:08 AM »

Just remember, you can usually tame any computer by following sound practices and installing a proper rfi receptacle (corcom).  I have my computer noise down to nothing by doing the following:

1.Power Supply Filtering (just had to solder the appropriate corcom filter, $10 from mouser or digikey)
2.Ferrites on noisy cables - mouse was bad, and I did all ethernet cables, speakers (line and power supply), threw one on the power cable for good measure.  Heck I just start putting some on now if they are cheap at a hamfest.
3.Make sure there are no gaps in the back where the cables come in and out, if so, cover with a metal tape or something
4.Sanded the interior lips of the case (metal, the only way to go) because paint on paint wouldn't help!

No noise, the case was an old cheapie from years ago, and power supplies are all over the place now a days, so you might spend lots and still have to solder a corcom in.

Also, if you have a CRT, junk that and get a LCD monitor.  BTW, in my experience, laptops don't seem to have these issues...  just FYI....
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AA5WG
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Posts: 496




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« Reply #12 on: February 12, 2011, 03:02:39 AM »

KB4MB:
Thank you.
Chuck
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