If the cable is shielded, and the garbage is on the PC's USB signal lines, an external ferrite won’t do any good. I don’t know if the cable is shielded or not, but if it is, then the garbage may not be on the shield … and perhaps the USB isolator might be worth a try. Maybe. I don’t know anything about that device …
Grant NQ5T > On Jul 21, 2020, at 5:36 PM, David Herring <[email protected]> wrote: > > Jim, > > Having percolated on this for a while longer, another thought comes to mind. > You mentioned that you tried a ferrite snap-on on the USB cable. In order to > really be effective, the USB cable would best be tightly wrapped around the > sides of the snap-on in something of a serpentine or sequential fashion, not > just randomly coiled up like a garden hose. I don’t know the specifics of how > you did it, but I mention this in case you did the garden hose method > originally…in that instance it would be a worthy exercise to rework your > choke, wrapping it properly and seeing if that then makes a difference. > > Also, it’s not unheard of to need multiple snap-ons with multiple turns each > to get enough impedance to choke out the unwanted signal. Especially if you > can’t get 6 to 8 passes through the center of a single snap-on. > > Oh, and once you get the snap-on wound, it’s highly recommended to cinch down > a zip tie around the circumference to ensure that both ends of the ferrite > material inside are making good contact with each other. If there’s the > slightest gap, the thing won’t work worth squat. > > Hope that helps, and that at least one of these suggestions you’ve been > getting on the reflector solves your artifact issue. ;-) > > 73, > David - N5DCH > > > >> On Jul 21, 2020, at 2:26 PM, Jim Brown <[email protected]> wrote: >> >> On 7/21/2020 11:10 AM, Ignacy wrote: >>> Perhaps the USB cable acts like an antenna. >> >> That often happens. But it can also excite a Pin One in whatever it is >> connected to on either end. >>> For RFI transmitted via USB cable, try USB isolator. E.g., >>> https://www.amazon.com/SMAKN-Isolator-Digital-Isolation-Industrial/dp/B00XXPO4UG >> >> If you have more money than you need, perhaps. But all it takes is to wind >> multiple turns of the "USB antenna" through a #31 ferrite clamp-on. They >> cost a few bucks if you buy from industrial vendors like Arrow and hit their >> minimum order of $50 for anything in stock. Fill up that quantity with more >> ferrite cores -- most of us need them to kill noise from the dozens of >> sources in our own homes! >> >> See http://k9yc.com/KillingReceiveNoise.pdf >> >> 73, Jim K9YC >> >> >> >> ______________________________________________________________ >> Elecraft mailing list >> Home: http://mailman.qth.net/mailman/listinfo/elecraft >> Help: http://mailman.qth.net/mmfaq.htm >> Post: mailto:[email protected] >> >> This list hosted by: http://www.qsl.net >> Please help support this email list: http://www.qsl.net/donate.html >> Message delivered to [email protected] > > ______________________________________________________________ > Elecraft mailing list > Home: http://mailman.qth.net/mailman/listinfo/elecraft > Help: http://mailman.qth.net/mmfaq.htm > Post: mailto:[email protected] > > This list hosted by: http://www.qsl.net > Please help support this email list: http://www.qsl.net/donate.html > Message delivered to [email protected] ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[email protected] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [email protected]
