THE DESIGN BRIEF

You're designing power conditioning for CE102 conducted emissions (10 kHz–10 MHz) but forgetting that same circuit has to survive CS101 bulk current injection up to 150 kHz. I've seen three designs this month fail CS101 at 100-150 kHz because their input filtering created resonances right where the susceptibility test hits hardest.

The rule: Keep your LC filter resonant frequency either below 50 kHz or above 200 kHz. Calculate it: f₀ = 1/(2π√LC). If you're between 50-200 kHz, you're asking for 20+ dB of amplification right in the CS101 test band. For AC inputs ≤100 A, I've measured 40 dB swings in transfer impedance when designers ignore this.

Your CE102 emissions filter and CS101 susceptibility response are the same network — design for both simultaneously, not sequentially.

• • IEC 60601-1-2 testing: Use manufacturer-specified cables port-by-port, not generic test cables — I've seen 15 dB difference in CISPR 11 radiated results
• • RE102 now covers 10 kHz–18 GHz in MIL-STD-461G — that upper frequency catches switching harmonics most contractors forget about
• • FCC Part 15 Class B limits are 14 dB tighter than Class A above 1 GHz — verify your home-use classification before test
• • CS114 bulk cable injection hits 10 kHz–200 MHz on all interconnects — your "clean" digital lines aren't exempt

• • MIL-STD-464 system-level EMC pairing with 461G for platform integration requirements
• • CISPR 11 harmonic distortion cross-references with IEC 61000-3-2 creating dual compliance headaches

Have you measured CS101 transfer impedance across your power input filtering? Reply with what frequency gave you the worst response — I'm collecting resonance data.

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