[RFI] USB qrm - what to do?

[Jim Brown]

On Mon,3/13/2017 2:34 PM, Steve wrote:
> Do common, run-of-the-mill USB cables have shields? The USB page on 
> wikipedia says a shield for the data pair is part of the USB 
> specification. Just wondering if cheaper cables omit the shield?

That's hard to know without cutting one open. :)  Unbalanced audio 
cables SHOULD be shielded, but I remember seeing cheapies where the 
"shield" was a wire, or was a spiral shield (not very good for RF).

This falls under the heading of trying to identify the better quality 
products, which usually means NOT buying the cheapest. :)

>
> I see on various web sites that some USB cables are advertised as 
> having a shield, it seems that web pages for most cables do reference 
> a shield. So if you want a cable with a shield, do you need to look 
> for those cables that specifically state that they have a shield?

Dunno. See above.

>
> One more question: If a USB cable has a shield, to what is the shield 
> connected? Perhaps the USB connector's outer metal shell? On both ends 
> of the cable? 

Yes and yes.

73, Jim K9YC