If you order the 28S206-271N5 coaxial connector from Rosenberger it does include the cap.
| MFR PART # | 28S206-271N5 |
|---|---|
| DIGIKEY PART # | 1868-1156-ND |
| MANUFACTURER | Rosenberger |
| DESCRIPTION | QMA Connector Plug, Male Pin 50 Ohms Free Hanging (In-Line), Right Angle Solder |
| DATASHEET | Click Here |