Topband: Elimination of Treadmill RFI on 160 meters

Tom W8JI w8ji at w8ji.com
Thu Jan 29 16:23:00 EST 2015


> Ferrites on the cord don't work on 160 meters if they are of
> the single turn class:  easy to use, but ineffective, clamp on beads.
> What does have a chance of working is 15 or so turns on a 2.4 inch O.D. 
> toroid.  Impedance varies as the square of the number of turns, so
> 15 turns is like 225 beads.  Fair-Rite Products also makes some large
> clamp on ferrites that you can wind with a lot of turns.  The advantage
> of these is that the plug on the end of the cord is no longer a
> constraint.

People just love adding series impedances, that what we do as hams. :)

Bypassing is usually much more effective than simply adding series 
impedances. Sometimes bypassing alone is more than enough. 90% of the time 
when I clean up an offshore SMPS for Ham use, it is just moving ground leads 
and bypassing.    :)

73 Tom





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