[Elecraft] RFI

[Fred Jensen]

The fact that clamp-ons reduced but didn't cure is a good sign.  A few 
turns thru ferrite toroids are ever so much more effective than the 
clamp-ons which I think is what you mean by "beads."  Mix 31 is best for 
HF, but 43 will also work well.  USB cables with an A-connector on one 
end and a B on the other will support 3 or 4 turns on a 1 1/2" toroid if 
you wind it using the B-end.  The finally wound toroid should be placed 
at the end of the cable connected to the device experiencing the RFI.  
Larger clamp-ons will often let you get two passes thru the ferrite for 
thicker power cords.  Common mode chokes are usually placed at the feed 
point of the antenna, but there are times when one on the coax at the 
rig will reduce RFI also.  And, don't forget any audio, keyboard, or 
mouse cables.  Visit k9yc.com for more exact, specific research on every 
choke known to humankind. 😉

73,

Fred ["Skip"] K6DGW
Sparks NV DM09dn
Washoe County

David F. Reed wrote on 12/19/2021 4:24 PM:
>
> Due to some HOA C&R, I am confined to attic and gutter antennas for 
> the time being.
>
> I am getting a bit of RFI on occasion into my PC; it manifests itself 
> mainly by apparently disconnecting the com port from Commander.  When 
> this happens, I can restore functionality by selecting a different com 
> port, and then re-selecting the original correct com port.
>
> I am grounded to a 10' ground rod about 8 ft. from the station via 2" 
> copper strap. I did install ferrite beads on the USB cables at the 
> back of the PC as well as on the power cord, and this has reduced the 
> frequency of occurrence, but I would like to eliminate it altogether.
>
> Any other ideas and suggestions would be most appreciated!
>
> Thanks & 73 de Dave, W5SV
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