[RFI] RFI Proof Computer speakers needed!!!

dgsvetan at rockwellcollins.com dgsvetan at rockwellcollins.com
Wed Nov 1 10:34:42 EST 2006


I read the excellent reply from Jim Brown, K9YC, and have only one other
comment to add.

As I understand it, most, if not all, sound cards in computers have the
capability to drive speakers directly (ie:  they have a built-in audio
power amp that can deliver a watt or two per channel to external speakers).
For some reason, most of the supplied speakers that come with system
packages are self-amplified, and these are the types that have most of the
problems as decribed by Jim.  It might help if your neighbor could switch
to non-amplified speakers, which is what I used for many years in my first
computer set-up.  Since the sound card is integral to the computer, it gets
a fair degree of shielding from the computer case and chassis, plus the
power source is internal.  The only "antennas" for the computer audio are
then the speaker leads themselves.  You will probably still need to treat
those with ferrites and by-passes per Jim's instructions, but it might be a
much less painful and time-consuming solution.  Of course, those ferrites
and by-pass caps would go as close to the speaker plug (where it conmencts
to the sound card) as possible.  Non-amplified speakers are just that, and
should have no non-linear devices within to become RF detectors.  Good

73, Dale

             Tim Duffy K3LR                                                
             <k3lr at k3lr.com>                                               
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             10/31/2006 11:17          [RFI] RFI Proof Computer speakers   
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               k3lr at k3lr.com                                               

I really need to find a solution for 40 and 15 meter RFI (caused by my near
field RF) that gets into my neighbors computer speakers. I have asked this
before, but I need to find a good set that is close to RF proof. I need to
them fixed once and for all and a new set of RFI proof speakers is the way

I have good ferrite rods (#43) on all leads (audio and power) now and it
but they still squawk.

Do you have any ideas?

Tim K3LR

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