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

[Pete Smith N4ZR]

Not on mine, Jeff - all plastic.


73, Pete N4ZR

On 1/16/2024 12:04 PM, Jeff (W4DD) wrote:
> No pin is needed.  There is a metal shell around the RJ45.
>
> On Tue, Jan 16, 2024, 11:40 AM Pete Smith N4ZR <pete.n4zr at gmail.com> 
> wrote:
>
>     Oh Joy - another thing to check.  I'm using a plain Ethernet Cat 5
>     patch cable from my amp to my computer.  Judging by how floppy it
>     is, I suspect no shielding at all - but a question - if there were
>     a shield, which pin on the Ethernet connector would it be?
>
>     73, Pete N4ZR
>
>     On 1/16/2024 10:22 AM, Jeff (W4DD) wrote:
>>     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 at contesting.com>  <mailto:rfi-bounces+w4dd09=gmail.com at contesting.com>  On Behalf Of Pete Smith N4ZR
>>     Sent: Tuesday, January 16, 2024 9:32 AM
>>     To:N1MMLoggerPlus at groups.io; RFI List<rfi at contesting.com>  <mailto:rfi at 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 viagroups.io  <http://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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