It is the MFJ927.
There is a control unit that goes inside. It connects to the output of your
rig, and to a DC power source.
This box puts the voltage onto the coax line to get power to the outdoor
portion of the tuner.
The QST article said it will tune with as little as 5 watts of rf.
Mike Duke, K5XU
American Council of Blind Radio Amateurs