The Return to the Chamber of Mysteries
Summary
Oxide engineers Robert and Stu discuss their recent EMC compliance testing for the Cosmo server rack, revealing the frustrating process of debugging unexpected electromagnetic emissions. They explain how accidental antennas form in hardware and describe their late-night efforts to localize a 26 GHz interference spike using methods like taping gaps and sanding paint. The episode highlights the "occult" nature of compliance engineering, where small manufacturing variations can cause major regulatory failures despite rigorous design.
Topics discussed
Adult baseball and knuckleball glove gestures
Using LLMs for HOA and planning commission disputes
Introduction to EMC compliance and accidental antennas
Electromagnetic radiation and interference basics
Antenna lengths, cavities, and PCB trace structures
Simulating emissions and signal return paths
FCC regulations and drive caddy spring fingers
The frustration of EMC chamber testing
Testing Rack Model 0.5 with 32 sleds
Unexpected emissions from QSFP transceivers
Debugging with tinfoil and baffling in the chamber
The religion of EMC and identifying the root cause
SIPI conference talk on optical transceiver analysis
Applying absorber material with tweezers
Validating the fix and factory implementation
Worst-case scenarios and driver design root causes
Final successful test and SIPI conference wrap-up
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