Three new silicon-carbon chains, SiC4H, SiC5H, and SiC6H, have been detected in a supersonic molecular beam by Fourier transform microwave spectroscopy. A detailed spectroscopic characterization of these and the previously described chains SiCCH, SiCN, and SiNC is given here. All six radicals are linear chains with (2)Pi electronic ground states and all have resolvable hyperfine structure in their lower rotational transitions; all except SiC5H have resolved lambda-type doubling. Because transitions of SiCCH, SiCN, and SiNC were also detected by millimeter-wave absorption spectroscopy in both spin components, for these the rotational, centrifugal distortion, and fine structure and hyperfine coupling constants were determined to high precision using the standard Hamiltonian for a molecule in a (2)Pi state. For SiC4H, SiC5H, and SiC6H, at least seven transitions in the lowest-energy fine structure component were measured between 7 and 30 GHz, and, at most, five spectroscopic constants were required to reproduce their spectra to a few parts in 10(7). The hyperfine coupling constants of the SiCnH radicals are fairly close to those of isovalent Cn+1H, indicating that the chemical bonding may be similar. The missing radical in the present sequence, SiC3H, may soon be found along with cyclic isomers of SiCCH and SiC4H. If SiC5H possesses strong electronic transitions in the visible like isovalent C6H, its spectrum should be detectable by long path optical spectroscopy.