Abstract: Systems for connecting RF coaxial cables are disclosed. In some embodiments, the systems include the following: a plug including a D-sub housing having two rows of eight RF coaxial contacts and a plurality of protrusions extending therefrom; a receptacle including a D-sub housing having two rows of eight openings and a plurality of indentations that are sized and positioned so as to mate with the protrusions extending from the plug, the receptacle including a rear unibody joined with the D-sub housing and a transition body positioned between and joining the D-sub housing and the rear unibody. The plug and receptacle are configured to provide about a 50-Ohm impedance across the system and the plug and receptacle are configured to operate under a ground-first condition.