Hi Eric,
Thank you for the CYLD05F measurements. Since you linked to the thread on The Audio Standard, I noticed that several people there use the CYLD05F differently: not inline in the active data path, but connected with a short Ethernet cable to an unused switch port. Some also connect the ground lead and report a slightly stronger effect.
I understand that your measurements were inline, where the CYLD05F did not improve the signal and even slightly worsened noise/jitter.
My question is narrower: from your experience with Drosselkabel/common-mode noise, could this one-sided use at an unused switch port still plausibly change the RF/common-mode behavior of the switch, even though it is not improving the active Ethernet signal?
And because you mention the old 2×2 trick for 100Base-TX: for such a short unused-port stub, would you expect a 2×2 cable to be more sensible than a normal 4×2 cable, or is that impossible to predict without measurement?
Best regards,