In this paper, we present a new dynamic-bias measurement setup and its application to the extraction of a nonlinear model for microwave field-effect transistors. The dynamic-bias technique has been recently proposed and relies on the use of low-frequency (LF) and high-frequency (HF) vector-calibrated measurements acquired, for instance, by means of a large-signal network analyzer. In this paper, we propose a new and alternative technique to perform the dynamic-bias measurements, based on relatively low-cost instrumentation commonly available in microwave laboratories. The new acquisition system is composed of a four-channel vector LF receiver (e.g., an oscilloscope) and a one-channel HF scalar receiver (e.g., a spectrum analyzer), which replace the eight-channel vector receiver. Moreover, the proposed architecture greatly simplifies the measurement setup and the calibration procedure. As a case study, a 0.25-μm GaN HEMT is considered. Dynamic-bias measurements, carried out by means of the proposed measurement setup, are used for the identification of a nonlinear model of this device. Finally, the model is fully validated through comparison with time-domain harmonic load–pull measurements carried out at 5 GHz.