How to pinpoint excessive radiated interference (RE) from data center switches?

Methods for locating excessive radiation emissions (RE) in the 30MHz-1GHz range for data center switches: Scan the chassis gaps, connectors, and PCB areas using a near-field electric field probe and spectrum analyzer. The peak signal frequency corresponds to a clock multiplier, such as 125MHz/250MHz. Use a current clamp to measure the common-mode current in the cable; a typical threshold >10μA indicates excessive radiation. Remove cables sequentially to narrow down the area. Connect a 10Ω-22Ω resistor in series with the suspected clock line to reduce the edge rate. Example: A certain model exceeded the 330MHz limit, located at the PLL clock pin. Adding a PBZ1005B-501Z0T ferrite bead (500Ω@100MHz) reduced the emission by 14dB, passing the Class A limit. This method allows for rapid location without an anechoic chamber.