RFI problems with the computer speakers are generally due to the
absence of the bypass components recommended by the amplifier chip
designers. I have seen several inexpensive computer speakers with
holes for the bypass caps on the circuit board (the chip maker's
reference design) but no parts. Generally, all it takes to make
the speakers "bullet proof" is adding the missing parts. In the
worst cases adding a couple molded 100 uH or 1 mH chokes in series
with the speaker lines inside the "amplifier" case resolved the
remaining RFI problems.
73,
... Joe, W4TV
On 8/2/2011 11:57 AM, ke9uw wrote:
> The hum is due to magnetic field in close proximity of the speaker...usually.
> Sometimes RF gets into them usually on the power cord. Ferrite fixes this,
> moving the speakers fixes the former.
> Chuck, KE9UW
>
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