Radio continuum spectra of the ten sources in our sample. Black points indicate total flux density data from single-dish and low-resolution interferometric measurements. The black dashed lines show the best-fit spectrum (power-law or log-parabolic). The parameters of the spectral fits are given in the insets and listed in Table 4. The red data points are the 1.7-GHz EVN flux density measurements presented in this paper. The red dashed-dotted lines for J0616−1338 and J0747+1153 show the power-law function fitted to the only available two flux density data points (VLASS and EVN), with the assumption that all the radio emission is confined to a small spatial scale corresponding to the compact VLBI component.