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Re: Topband: Elimination of Treadmill RFI on 160 meters

To: "Richard \(Rick\) Karlquist" <richard@karlquist.com>, "Carl Clawson" <clawsoncw@gmail.com>, "Topband Reflector" <topband@contesting.com>
Subject: Re: Topband: Elimination of Treadmill RFI on 160 meters
From: "Tom W8JI" <w8ji@w8ji.com>
Reply-to: Tom W8JI <w8ji@w8ji.com>
Date: Thu, 29 Jan 2015 16:23:00 -0500
List-post: <topband@contesting.com">mailto:topband@contesting.com>
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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