This application note describes testing S-parameters under pulsed conditions with the R&S ZVA vector network analyzer and either the ZVAX24 Extension unit with pulse modular option or the R&S SMF signal generator with pulse modulator as a signal source. In addition a constant power level calibration for applications requiring high drive power for test and measurement of device under test (DUT) is also included. A LDMOS S-band radar power transistor is used as example DUT. The pulse profile mode of the R&S ZVA is used to analyze the time-dependent behavior of the DUT.