Ferroelectric liquid crystal (FLC) materials exhibiting the cholesteric (N*), smectic A (SmA) and chiral smectic C (SmC*) phases have been studied by electro-optical and dielectric investigations. In the dielectric measurements, we have studied the soft mode in the SmC* and SmA phases. From experimental data, we have evaluated the soft mode rotational viscosity and the electroclinic coefficient in the SmA phase. All results are discussed and compared with previous studies performed on other homologues of the same series. The main result is that the relaxation process, observed in N* phase for the C8, C10 and C11 materials and identified as a soft-mode-like mechanism, disappears for C12.