Andrew Rossmann hath wroth:

My guess would be that these chokes filter ripple current from a high
frequency switch mode PSU, the best way to stop them ringing is with fast
setting araldite epoxy - allow it to run into the holes through the ferrite
where the wires run through.

The power supply is your basic plug-in brick. I tried both the
original and a RadioShack that is heavy enough to NOT be any form of
switching supply. Both are standard 120V in, 12VDC/1A out.

The wall wart just supplies unregulated DC power to BEFSX41. The
switching supply inside the BEFSX41 takes the 12VDC down to 3.3VDC to
run the router. I couldn't find the FCC ID to display the inside
photos from the FCC web pile. The various WRT54G wireless routers are
similar inside. Note the photos at:
http://www.linksysinfo.org/modules.p...showpage&pid=6
In the upper left corner of the board, you'll see the same ferrite
beads. The switching regulator is nearby. The ferrite beads keep the
RFI from leaking out of the box via the 12VDC power cable.

Incidentally, I use hot melt glue instead of epoxy for vibration and
noise reduction. It makes less of a mess. If desperate, I use RTV
(silicon rubber goo).


--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558