[Al Skierkiewicz]

The manufacturer of the original D connectors was looking to expand their product line and came up with a hybrid connector in a D shell that allowed a small number of coaxial and normal pins combined into one connector. Although the origianl application was for military or Nasa use, video manufactures and RF designers both have used them in designs for many years. I believe the connector is actually a push on SMA connector although I don't remember the exact mil spec part # off the top of my head. They are still available but expensive.