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Re: [RFI] just what everyone needs!

To: "Cortland Richmond" <ka5s@earthlink.net>, rfi@contesting.com
Subject: Re: [RFI] just what everyone needs!
From: "Dale Svetanoff" <svetanoff@earthlink.net>
Reply-to: svetanoff@earthlink.net
Date: Mon, 10 Sep 2012 14:49:02 -0500
List-post: <rfi@contesting.com">mailto:rfi@contesting.com>
Cortland,

Thanks for the info.  I had not heard about the rather significant product
failure that you describe, but I believe it.  I don't know if that is the
same product to which I was alluding, but the name that comes to mind is
"Eupen".  Failure of the sort you describe is probably why I have not seen
any ads for that product in a very long time.

73, Dale
WA9ENA  


> [Original Message]
> From: Cortland Richmond <ka5s@earthlink.net>
> To: <rfi@contesting.com>
> Date: 9/10/2012 10:52:08
> Subject: Re: [RFI] just what everyone needs!
>
> There was a (German?) firm some 10 or 125 years ago selling cable and 
> coax whose jacket was loaded with ferrite powder. However, over  a 
> relatively short time, years, not decades, and maybe less than that, the 
> binder failed and pieces started falling-off. This happened in some 
> other rubber-plastic/ferrite sheet and tubing materials of the time, 
> too. I forgot the company name -- and I don't need it!
>
> Before retiring from GE I once used some newer absorbing sheet material 
> to trouble shoot a GHz range immunity problem in a less than adequately 
> shielded cabinet. But I wouldn't trust it to stay put in an airplane.
>
> And WRT to ferrite on coax, I once found a lab problem where conducted 
> emissions on the OATS table power got onto the coax shield and then (via 
> LPDA imbalance) back to the EMI receiver. That was fun.  Instead of 
> putting ferrites on the antenna coax, they rerouted power through a 
> different conduit.  Some will know the lab, up Silverado Canyon.
>
> Cortland Richmond
> KA5S
>
>
>
> On 9/10/2012 1107, Dale Svetanoff wrote:
> > ... On a related note, back in the 1990s, I was Chair of an IEEE
standards
> > writing working group making major revisions to IEEE Std-299, which
deals
> > with measuring the RF shielding effectiveness of shielded enclosures. 
Some
> > of the working group members noted that coax cable with ferrite-loaded
> > jacket was a (then) new item available from at least one manufacturer,
in
> > Europe, I believe.  We ran some actual tests using ferrite loaded coax
(in
> > the outer jacket) to see if the ferrites affected readings being taken
when
> > making measurements (the coax was being used to carry signal from a
sense
> > antenna to a spectrum analyzer or EMI receiver).  Yes, it did, so we
had to
> > specify use of cable that had continuous (or multiple load areas) on the
> > coax, as opposed to single point loading, because the ferrites caused
> > either suck-outs or reflections (depending upon frequency) when used
within
> > an enclosure being measured.  Continuous jacket loading minimized these
> > effects.  Note that loaded jacket coax does not affect the signal within
> > the cable itself.
> >
> > 73, Dale
> > WA9ENA
> >
> >
> >   
>
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