Radio spectra of our sample of nine quasars observed with GMRT and including LoTSS-DR2, RACS, FIRST, and VLASS measurements. Non-detections in the FIRST and VLASS survey are given as 3σ upper limits. Each spectrum is well described by a power law with varying spectral indices (indicated in the bottom left corner) and there is no evidence for a spectral turnover, except for J0309+2717 (see Sect. 4.2.2). The upper x-axis indicates the rest-frame frequency. The flat or negative slopes of these spectra suggest a turnover below 1 GHz in rest-frame.