A pulse generator comprises a header connector assembly coupled with a housing. The header connector assembly includes a connector assembly and a header enclosing the connector assembly. The connector assembly includes an electrically insulative segment, a first electrically conductive segment, and a second electrically conductive segment axially spaced apart from the first electrically conductive segment by the electrically insulative segment. Each electrically conductive segment includes a connector ring, a spring housing and a spring supported by the spring housing. The connector ring and spring housing are in electrical communication with each other. The electrically insulative segment includes an insulator ring that is positioned between the first and second electrically conductive segments. The insulator ring includes a first end and a second end axially opposite the first end. The first end includes a first recess that opens axially and receives therein a portion of the first electrically conductive segment.