[RFI] Recommended PC Components for Low EMI/RFI?

[Rob Atkinson, K5UJ]

My experience has been the tough thing is keeping rf out of the pc's audio 
speaker system.  for a lot of hams it may not matter if they don't have 
sound from the pc but if you want to run your rig and Echolink at the same 
time it is an issue.   A lot of hams use Echolink as a sort of free "order 
wire" (signal corps term) to coordinate on-air stuff...EME, mw shots, 
testing new setups on HF etc.

For the other RFI avoidance, I'd consider simply positioning the pc away 
from the RF gear and running long mouse, keyboard and monitor cables.  At or 
near each end you can put a bunch of ferrite chokes on them and use a LCD 
monitor too by the way.   Well, I guess on the mouse and keyboard wires you 
only need to have chokes near the pc.  The hash field around a pc varies but 
usually drops off around 4 feet away so at that point it's not overwhelming 
things you want to protect.   Note:  I have not done this--just an idea to 
consider--I do not know if it will work or not, but it's probably nice to 
get the pc away anyway, since that reduces operating position clutter.   
comments on whether or not this is bad advice welcome but please post to the 
list; not me.  Tnx.

Rob Atkinson
K5UJ

From: Phil Duff <na4m at arrl.net>
To: rfi at contesting.com
Subject: Re: [RFI] Recommended PC Components for Low EMI/RFI?
Date: Sun, 28 Dec 2003 05:50:23 +0000

At 04:10 12/28/2003, Colburn wrote:
>I am about to assemble a new PC.  I would like to select
>components that have better than average resistance to
>external RF and minimal output of same.
>
>I'd like to start with the motherboard.  While I am fond
>of the features of the EPoX 8KRA2+ (I am told that it is
>just now out of production and replaced by the 8KRAI so
>dealers still have them). I cannot find any data re.
>EMI/RFI specs. (Indeed there is little if any comparative
>data between mobos anywhere.)
>
>Then I need to select a case and power supply:  ATX,
>400 watts or better, front panel USB access ... but
>aluminum or steel?  I don't care about looks, certainly
>not about clear side panels or colorful lights ... just
>stability and low EMI/RFI.

I went thru this same exercise about 2 years ago.

My approach was to select the case and power-supply first as it's the 
computers first line of "defense" in EMI/RFI suppression.

I chose an Antec steel mid-tower case and power-supply.  The Antec cases are 
well designed and the power-supplies seem quiet.

I've had two different mobo's in this Antec case both running an AMD Athlon 
Thunderbird cpu at 1.2ghz - the first was a ASUS mobo with which I was 
disappointed when one of it's EIDE channels died and corrupted a harddisk 
after a few months.  I replaced the ASUS with a FIC mobo and have been very 
pleased.

As a point of reference - this 1.2ghz system has far and away much less EMI 
than my old generic case and p.s. that ran a Cyrix P166+ cpu.  I have no 
noticeable EMI or digital noise in my receivers that I can blame on the 
computer.   And have never had the system crash due to RF getting into the 
system at power levels up to 1.5kw.  The computer is in the radio shack BTW.


73 Phil NA4M




_. ._ ...._ __   _. ._ ...._ __   _. ._ ...._ __   _. ._ ...._ __
Phil Duff  NA4M   Ann Duff  Georgetown, Texas


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