Thx Gedas, now I’m checking cables. 😳
Tom JWM
Sent from my iPhone
> On Feb 28, 2019, at 6:36 PM, Gedas <w8bya@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
>>
>>
>>
>> _______________________________________________
>> RFI mailing list
>> RFI@contesting.com
>> http://lists.contesting.com/mailman/listinfo/rfi
> _______________________________________________
> RFI mailing list
> RFI@contesting.com
> http://lists.contesting.com/mailman/listinfo/rfi
_______________________________________________
RFI mailing list
RFI@contesting.com
http://lists.contesting.com/mailman/listinfo/rfi
|