[Open-graphics] Info on the 13W3 connector

[mykrowatt at comcast.net]

   I came across this yesterday while searching for a connector for a customer's project.
   It turns out that the full part number is DBM-13W3ST.  It comes from Cinch-Jones, which is now part of ITT-Cannon.  The 13W3 character string describes the pin layout, which means 13 pins total, 3 of them coaxial or power, in a B-size D-sub shell.  Various special options can be ordered.
   The 3 large cavities can be stuffed with 50 ohm coaxial, 75 ohm coaxial, or high-current power pins.  The short-form catalog I have says that the 50 ohm contacts are good to 900 MHz, and the 75 ohm contacts are good to 2 GHz.  No VSWR or attenuation numbers are given, but presumably a full data sheet is obtainable.

   This contrasts with the DVI connector.  I think JRT said earlier that it's rated to 400 MHz, which seems reasonable to me, given its design.  The current generation of high-end monitors is approaching its ultimate performance limits on both the analog and digital pins; I don't think it could be improved much without radical change.
   I'd expect that the present 13W3 could handle displays up to at least 6 megapixels, and there's plenty of room for further improvement in the design of the coax inserts; coaxial connectors of those dimensions routinely carry 10 GHz radar signals.  Anything over 2 GHz would require something better than cheap consumer-grade small-diameter coax, though.
   At the far end, the BNC itself runs out of flatness somewhere between 1 and 2 GHz, but there are plenty of higher performance coax connectors, including an upgraded 13W3 itself.
   Some of this may be of interest for later-generation video boards.  For the most demanding requirements, I'd put each line driver amp right next to its connector pin.