A simple, classic 4:1 current balun based on proven technology for 60 years. For matching balanced line (ladder line) to unbalanced line (coax) such as feed line to tuner applications. Attach a PL259 to the unbalanced port on the back of a tuner through a terminal block (p/n 865) to ladder line. Device matches balanced to unbalanced feed line and centers tuner’s matching capability.