On 11/9/2020 4:22 PM, Steve Dyer W1SRD via RFI wrote:
Does the shielding help prevent RF getting *into* the cable?
With these new 4 wire HVAC control systems I worry about RF getting in
the system too.
Hi Steve,
In my experience, common mode is the primary issue at HF, and probably
at VHF. I say that because a clamp-on ferrite has long been the weapon
of choice to satisfy compliance testing, which only happens at VHF and
above, and wound ferrite chokes usually solve it at HF. My educated
guess is that Pin One problems inside the gear are what couples common
mode into and out of the equipment. The simple clamp-ons used by
compliance engineers are also common mode chokes, simply optimized to
place the resonance at VHF.
73, Jim K9YC
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