The MFJ-1312D is a 13.8 Vcd 500 mA AC Adapter with a 2.1mm jack. It is used to supply 110V power to a large range of MFJ devices.
AC SW ADAPTOR, 13.8VDC,500MA,100-240VAC,2.1MM PLUG
Description
MFJ Power Supply AC Adapters are 12 or 13.8 V DC adapters featuring 2.1mm power plugs. They provide DC current to power anything from automatic antenna tuners to QRP rigs and other small-equipment applications. They are available in several current ratings.