[RFI] Bonding to a PC

[Thomas Mills]

Thx Gedas, now I’m checking cables. 😳
Tom JWM

Sent from my iPhone

> On Feb 28, 2019, at 6:36 PM, Gedas <w8bya at mchsi.com> wrote:
> 
> Speaking of shielded cables I wanted to share something I have encountered on more then one occasion when I worked in the aerospace industry.
> 
> We had an issue with a product during some specialized radiated tests. Tasked with the investigation I found that the item was using shielded USB cables, as expected, the only problem was the maker of the cables (a large company that starts with an L and ends with a com) was not terminating the cable shield in any way. What was more disturbing to me was that I had to explain to two of their engineers that the shield had to be properly terminated to do any good. Just because it has a shield or braid around the conductors means absolutely nothing.
> 
> So, just because a cable says "shielded" do not assume it is properly terminated on both ends.
> 
> Gedas, W8BYA
> 
> Gallery at http://w8bya.com
> Light travels faster than sound....
> This is why some people appear bright until you hear them speak.
> 
>> On 2/28/2019 5:12 PM, Jim Brown wrote:
>>> On 2/28/2019 11:34 AM, N4ZR wrote:
>>> I want to try to manage RFI in my shack, among other things, by bonding all chassis together, including my shack computer, but the question has come up - where can I find chassis ground on a PC without serial or parallel ports? Is there a design standard, such as connecting the power supply chassis to ground buses on the motherboard, that makes this easy or does it have to be figured out PC by PC? 
>> 
>> Bonding should always be to the shielding enclosure (chassis) if there is one, and this is the required connection point for the Green wire. DB-connectors are sometimes bonded, so consider the VGA connector (if there is one). To make that connection to my laptops, I solder a short bonding conductor to a lug small enough to fit under the retaining screw for the DB connector, with a single Power Pole on the other end.
>> 
>> If your PC only has USB ports, try making the connection to the shell of one of them by sacrificing a USB cable like one of these.
>> 
>> https://www.amazon.com/Cable-Matters-USB-Black-Feet/dp/B00C7RXR72
>> 
>> USB is carried on twisted pairs, and cheap cables are often unshielded.  If you're experiencing RFI, using shielded cables might help.
>> 
>> 73, Jim K9YC
>> 
>> 
>> 
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