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Re: [RFI] USB Cable Shield Resistance was: Re: [N1MM+] open question abo

To: "'Pete Smith N4ZR'" <pete.n4zr@gmail.com>, <N1MMLoggerPlus@groups.io>, "'RFI List'" <rfi@contesting.com>
Subject: Re: [RFI] USB Cable Shield Resistance was: Re: [N1MM+] open question about RFI & USB
From: "Jeff \(W4DD\)" <w4dd09@gmail.com>
Date: Tue, 16 Jan 2024 10:22:21 -0500
List-post: <mailto:rfi@contesting.com>
Pete, just another data point based on my experience with shielded Ethernet 
cables.  Excerpt from one of my PPT's follows.  I found the shield connections 
to be intermittent.



Do Not Use Shielded Ethernet Cables from the Common Internet Sites
The shield is not soldered to the metal RJ-45 shell.  I measured 2-20 ohms on a 
group of 5 jumper cables shell to shell.  Mouser Electronics has Amphenol 
Ethernet cables ($7) with the drain wire soldered to the metal RJ-45 shell at 
both ends.  Resistance was less than 1 ohm for each of 5 cables measured (view 
the spec sheet at Mouser.com).

Jeff, W4DD

-----Original Message-----
From: RFI <rfi-bounces+w4dd09=gmail.com@contesting.com> On Behalf Of Pete Smith 
N4ZR
Sent: Tuesday, January 16, 2024 9:32 AM
To: N1MMLoggerPlus@groups.io; RFI List <rfi@contesting.com>
Subject: [RFI] USB Cable Shield Resistance was: Re: [N1MM+] open question about 
RFI & USB

Interestingly, I just tested the shielding on a USB A to USB C cable I have, 
which looked like it should be fine, with a transparent jacket over woven 
shielding and a big ferrite bead - about 1 meter long, and measured 2.7 ohms - 
not good.  What should be consider to be the upper permissible shield 
resistance?

Moving this issue to the RFI reflector now...

73, Pete N4ZR

On 1/16/2024 5:01 AM, Janez Majdic via groups.io wrote:
> Maybe also good to read:
> https://www.yoctopuce.com/EN/article/usb-cables-shielding-matters-as-w
> ell
>
> Regards, Janez - S51J
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