[RFI] PC Speaker "Buzz"

[Paul Christensen]

You've gotten good advice so far.  If RFI ingress is occurring on the input
to a PC *power-amp* speaker system, then probably the most effective and
least invasive way to mitigate the common mode current is to wrap several
turns of the input cable through #31 mix ferrite cores.  Wrap as close as
possible to the PC speaker's amplifier input.   It's the *turns count* that
adds series common mode impedance.  Have a look at K9YC's materials in the
link below.  For several mix types, he shows the number of turns required to
achieve a target choking impedance for a given frequency.

http://audiosystemsgroup.com/RFI-Ham.pdf

Paul, W9AC

-----Original Message----- 
From: Tony
Sent: Tuesday, June 30, 2015 8:08 PM
To: rfi at contesting.com
Subject: [RFI] PC Speaker "Buzz"

All:

What is the best method of reducing RF getting into ones PC speakers? Is
it best to use ferrite beads and toroids in mix 31, 43 or a combination
of both?

Thanks

Tony
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