21 Pin Decoder (NEM660)
The 21 Pin MTC Connector is a Mobile Decoder Locomotive Interface intended for sound applications. This is a direct PCBconnector (there is no wiring harness), the decoder is intended to plug directly onto a fixed pin header inside the locomotive. MTC connectors have additional connections compared to regular DCC connectors to allow for loudspeakers and Hall sensors for chuff synchronization. However, while intended for sound, not all 21 pin MTC decoders are sound-capable and not all locomotives equipped with 21 pin MTC are sound-ready.