Topband: Common Mode

Mike Waters mikewate at
Mon Nov 12 20:06:26 EST 2018

Excellent! We can't attach files here, but you can download it. His website
is Download the rfi-ham PDF. There is no better information about
common-mode chokes available anywhere else.

73, Mike

On Mon, Nov 12, 2018, 5:02 PM Arthur Delibert <radio75a3 at> wrote:

> David --
> Suggest you take a look at the attached paper by Jim Brown.  I live in a
> fairly dense suburb where every house (including mine) has all the latest
> RF noise-makers.  Following Brown's suggestions, I've put large 31-material
> clamp-on ferrites on both ends of my receive antenna feedlines (and
> sometimes one in the middle), and it makes a very clear difference.
> Regards,
> Art Delibert, KB3FJO
> ________________________________
> From: Topband <topband-bounces at> on behalf of Rodman, David
> <rodman at>
> Sent: Tuesday, October 23, 2018 6:41 AM
> To: topband at
> Subject: Topband: Common Mode
> I purchased some 7mm dia snap on cores for RG6 receive antenna coax.  I
> was wondering if anyone had any experience or suggestion as to how many one
> would place on each lead.  The feed lines are about 50% on the ground with
> grass growing over or buried 2-3".  The lengths vary from 300' to 750',
> depending on the antenna I am using for listening.  I was planning to place
> them inside the station.  I have nothing now and thought this would be
> acceptable versus removing connectors and placing beads?  Thank you.
> ---
> David J Rodman MD
> Assistant Clinical Professor
> Department of Ophthalmology
> SUNY/Buffalo
> Office 716-857-8654
> _________________

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