The gaping hole in FCC EMC regs is that they fail to consider conducted
emissions on anything but the power line. Thanks to widespread "Pin One"
problems at connectors for signal and control lines, common mode current
on these cables, usually on cable shields) is a primary cause of EMC
issues, both incoming and outgoing. The "Pin One Problem," first
identified by an engineer with a ham background working in pro audio, is
the failure to terminate cable shields to the shielding enclosure at the
point of entry. A similar problem often occurs when the "green wire" of
the power line fails to contact the shielding enclosure directly at the
point of entry. The first two links were written for a newsletter for
sound contractors. The third is my tutorial for hams. The Pin One
Problem is addressed beginning on Page 8.
http://k9yc.com/Pin_1_Revisited.pdf
http://k9yc.com/Pin_1_Revisited_Part_2.pdf
http://k9yc.com/RFI-Ham.pdf
Neil Muncy's original work on this was published in the June 1995
Journal of the Audio Engineering Society, which can be downloaded from
aes.org (modest fee). JAES is in the engineering libraries of most
universities.
73, Jim K9YC
On 4/11/2022 3:39 PM, David Eckhardt wrote:
It was the ONLY product in my some 30+ years as an EMC/RFI engineer we
had to install a 35 dB, yes, you read correctly, 35 dB attenuator (!!!)
between the product connection to the AC power (LISN) and the conducted
emission receiver.
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