Placement of the Ferrite Bead 2

[Chris0222]

I have a wiring harness that calls out the use of a Ferrite Bead. The drawing is not clear if to terminate the sheld to ground before or after the Ferrite Bead. The sheld is already grounded on the other end of the harness, about 3 feet away.

Thanks, Chris

 

[hacksaw]

sort of depends on the designers intent, but if placed on the outside of the shiled it does not interfect with the signal being carried by the coax

 

[VEBill]

To expand upon hacksaw's response, if the ferrite bead is installed around only the center conductor (terminating the shield "before" the bead), then the inductance of the bead *will* potentially impact the signal carried within the coaxial cable. It's not likely the desired outcome, but one never knows...

More typically, they're installed over the entire coaxial cable to help reduced common mode currents.

The relative size of the specified cable and specified bead should provide a strong hint.

 

[zappedagain]

Most EMI/EMC issues are common mode, so typically your shield will be going through the bead too.