Considering multiple turns through a ferrite 'bead': Yes, more turns will
yield better isolation. However, much beyond 3 or 4 turns, and one
approaches a limit of effectiveness. Cram as many turns as is possible on
a single bead increases capacitive coupling between the turns and
ultimately limits the effectiveness. The windings should be 'ordered' and
not wound in a hap-hazard manner which also reduces inter-winding
capacitance.
Best practice: Employ shielded cables with the shield terminated on both
ends. CAUTION: Many of the modern "shielded cables" may be rather
compromised due to cost cutting regarding integrity of the shield
installation and type. When choosing a shielded cable, its best to test a
reasonable length before buying a significant amount of the cable.
Dave - WØLEV
On Tue, Feb 25, 2020 at 2:13 PM Joe <nss@mwt.net> wrote:
> Want to make sure RF stays out of my audio and Mic wires.
>
> Now I see many small clip on ferrites like these,
>
>
> https://img2.freepng.es/20180420/bgw/kisspng-ferrite-bead-ferrite-core-electronic-filter-electr-bead-5ad99198298d83.5874384515242080241702.jpg
>
> Now is it better to get some with a larger hole, so that multiple passes
> can be made, like this?
>
>
> https://www.gearslutz.com/board/attachments/remote-possibilities-in-location-recording-amp-production/610734d1480262732-led-lights-hum-how-best-deal-ferrite-chokes-_.jpg
>
> And when it comes to doing multi pass if that is better to do,
> What is best performance, just cram in as many turns as you can as seen
> above?
>
> Or wind the turns in an organized fashion, like a toroid inductor, where
> the turns do not overlap each other, kind of like this?
>
> https://i.ytimg.com/vi/LuMlM8zWQFk/maxresdefault.jpg
>
> What is best practice to keep RF out of audio and Mic lines? 160 through
> 10 meters.
>
> Joe WB9SBD
>
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> http://lists.contesting.com/mailman/listinfo/rfi
>
--
*Dave - WØLEV*
*Just Let Darwin Work*
*Just Think*
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