The probes are electrically shielded, active and have a sheath current attenuation. With the correction curves the output voltage of the probe can be converted into the respective magnetic field or the flowing current of the conductor. They are connected by a Bias tee BT 706 to a spectrum analyzer or an oscilloscope with a 50 Ω input. A wall plug transformer and a Bias tee are included in the scope of delivery. Both power the integrated preamplifier in the probe head.