The PA 3010 is connected to the 50 Ω input of a spectrum analyzer or oscilloscope. The PA 3010 is powered by a provided plug-in power supply. The preamplifier can be used, for example, to amplify the measurement signals of the Langer near-field probes. For this purpose, a near-field probe with a suitable frequency range and corresponding cable is connected to the input of the preamplifier.