  The temperature dependence of the low-temperature dielectric response is
studied in o-TaS$_3$ samples doped by Nb, Se, and Ni and for nominally pure
ones. It is found, that the low-temperature dielectric constant depends
anomalously on doping and is higher for doped crystals, whereas the temperature
dependence of the characteristic time of all samples follows the activation law
with nearly the same activation energy $\sim 400$ K (T>20 K). The observed
behaviour is inconsistent with all available explanations of the
low-temperature dielectric anomaly.
