[RFI] ethernet switch with shielded case or low emission spectrum

[Jim Brown]

On 3/28/2018 11:22 PM, Jeff Blaine wrote:
> I was hoping someone may have found a "quite" switch that could be 
> recommended.  Some of the semi-pro (e.g. Netgear home-office rack 
> mount) stuff has metal cases -- but I don't know if that actually 
> means they are quieter.

Hi Jeff,

I have no equipment recommendations, but can at least offer these thoughts.

Unfortunately, shielding requires FAR more than putting circuitry in a 
conductive enclosure. Many such boxes are "clamshells" with paint 
insulating the places where they SHOULD meet, so they're not really 
shielded. Every cable SHIELD that enters a shielding enclosure must be 
bonded to the enclosure AT THE POINT OF ENTRY. Any unshielded conductors 
must go through feed-through caps that shunt RF to the chassis, but 
doing that with data circuits would likely trash the data. :) This 
problem can be solved by one or more ferrite common mode chokes on the 
cable.

73, Jim K9YC