[RFI] Update - USB RFI

[Pete Smith N4ZR]

Plugged each of my usb devices into the computer separately, and 
discovered that most of the RFI is coming from the cable to my Seagate 
USB hard drive.  It is a USB 3.0 device fed off a USB 2.0 port,  I then 
wound 5 turns of the cable - all that would fit - on a Type 31 big 
snap-on, and all but 1-2 dB of the RFI disappeared, roughly a 10 dB 
improvement from this device alone.

Next step is to wind 10 or more turns on a USB extension cable as Dave 
suggested and see if it reduces further.

On the audio display of HDSDR I can see pretty distinct hum lines at 
multiples of 120 HZ.  I intend to bring everything I can to a common 
ground bus and see if that helps, then go sniffing for other hum genrators.

Thanks everyone for your suggestions!


-- 

73, Pete N4ZR
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