[Elecraft] RFIth

[Bob McGraw]

For those using the clamp-on ferrite devices, when installing them, be 
sure part A closes completely and solidly contacts part B.   Otherwise, 
there is no flux path and the device is ineffective.  If it is closed 
and loose on the cable, then that's good.   If it is closed or difficult 
to close, it isn't large enough for the cable and will likely not be 
effective.   Any gap between the halves renders it worthless for the 
application.

73

Bob, K4TAX


On 12/20/2021 6:18 PM, elecraft-request at mailman.qth.net wrote:
> Message: 11
> Date: Mon, 20 Dec 2021 08:34:24 -0800
> From: Dave<dave at nk7z.net>
> To:elecraft at mailman.qth.net
> Subject: Re: [Elecraft] RFI
> Message-ID:<8cdb19ae-b111-5a6c-3f2a-d29efdd25351 at nk7z.net>
> Content-Type: text/plain; charset=utf-8; format=flowed
>
> Hi,
>
> Purchase some FT240-31 ferrite cores,
> (https://www.farnell.com/datasheets/1912768.pdf), and wind at least 5
> turns of each cable going to, or from, the computer through the ferrite.
>
> I have several of these, and they stopped ALL of my RFI issues with my
> computer, and with a weather station I have as well.
>
> Shop around looking for the best price, some folks are asking 10 bucks
> for one of these, others are asking 5 bucks...  I use Newark, and
> Digikey as my goto places.
>
> Also look to K9YC's site, for more information on how to make the chokes...
>
> http://k9yc.com/2018Cookbook.pdf
>
> 73, and thanks,
> Dave (NK7Z)
> https://www.nk7z.net
> ARRL Volunteer Examiner
> ARRL Technical Specialist, RFI
> ARRL Asst. Director, NW Division, Technical Resources