[Amps] World's worst coax connectors

[Jim Brown]

Interesting indeed -- I first proposed a concentric capacitance in the 
course of an AES EMC WG meeting as a solution to the need to break the 
shield at one end of a cable to prevent excitation of legacy Pin One 
Problems. I was thinking "feed-thru" for the shield. Joanne Dow, a WG 
member based around LAX, suggested the addition of the bead. This was in 
the late '90s, and I knew nothing of ferrite then! It was John Woodgate, 
from the UK, who proposed the circumferential array of SMT caps, and who 
subsequently ran extensive tests of an engineering sample. Engineering 
people from Neutrik had long been active in the WG.

Another critical piece of this series of Standards came from Bill 
Whitlock, whose work on the Balanced Interface showed that if the cable 
shield is interrupted, that the interruption must be on the receiving 
end. This was counterintuitive to some of us, including me, but Bill 
changed our brand of booze. In addition to being Chief Engineer of 
Jensen Transformers, the world's best, and having done extensive design 
work at major LA recording studios, Bill has had serious RF consulting 
projects in the UHF range. :)

The resulting product was a quite effective band-aid for VHF and UHF in 
legacy equipment with Pin One Problems. Most (but not all) of the WG 
members who made the most important contributions to AES EMC Standards 
were hams.

I was (and still am) Vice-Chair of the EMC WG, and chaired the writing 
group that developed that series of Standards.

Also critical to our final product was understanding the difference 
between shielding and grounding. We connect the shield to the shielding 
enclosure NOT to "ground" it, but to make the shielding continuous! It 
was the late Ray Rayburn (a ham) who came up with the phrase "shielding 
enclosure" to solve some arguments with the "physics-challenged."

I learned a LOT from the serious brain-power during my work on AES 
Standards. It was like free grad school!

73, Jim K9YC

  On 4/23/2023 4:07 PM, Paul Christensen wrote:
> The discussion in the link above concludes with a reference to the Neutrik
> EMC series XLR connector.  It uses an integrated capacitor between Pin 1 and
> the shell.  For anyone not yet bored by the discussion, have a look at the
> bottom table, "Pin 1 Problem" in this Neutrik application note where the EMC
> capacitors are shown:
> 
> https://www.neutrik.com/media/9117/download/typlical-application-emc-xlr.pdf
> ?v=1
> 
> I'm a bit skeptical of the effectiveness across a broad range of EMI/RFI but
> it looks like it may be an "AES acceptable" way to join two midpoint XLR
> connectors.  The top of the application points to my original concern.  See
> "Interrupt of Circumferential Shield," and "Connector Shell Floating."
>