Summary: A crimp on connector originally used for telephone equipment. It is also used for LocoNet and XpressNet connections.
The connector was originally used for telephone equipment. The RJ means Registered Jack.
The six conductor connector (sometimes only the center two or four are used) that is typically used for connecting telephone equipment. Widely used in DCC for bus connections and cab plugins.
The RJ11, 12, 14 and 25 are the same physical size, the difference is the RJ12 is a 6 position, 6 conductor device (6P6C). See the LocoNet article for more information on the RJ connector series.
- RJ12 is for solid wire
- RJ25 for stranded wire
Using the incorrect type for the wire will result in problems later. The "stabs" on each pin are designed for a specific wire type.
To identify the pins, hold the RJ connector with the tab facing down, and the opening for the cable facing you. Pin #1 is the leftmost pin.