The EMCO 3701 is a wire clamp-on device designed to be attached directly to the mains cable going to a piece of equipment. The purpose is to measure conducted emissions on the line where its impractical to use a LISN e.g. the cables feeding a distribution panel. The probe will exhibit a blocking effect on the power frequency whilst permitting measurement of the RF content. It presents an impedance of at least 1500 ohms to all voltages on the line.