  Layered van~der~Waals materials of the family TaTMTe$_4$ (TM=Ir, Rh, Ru) are
showing very interesting electronic properties. Here we report the synthesis,
crystal growth and structural characterization of TaIrTe$_4$, TaRhTe$_4$,
TaIr$_{1-x}$Rh$_{x}$Te$_4$ ($x = 0.06$; 0.14; 0.78; 0.92) and
Ta$_{1+x}$Ru$_{1-x}$Te$_4$ single crystals. For Ta$_{1+x}$Ru$_{1-x}$Te$_4$
off-stoichiometry is shown. X-ray powder diffraction confirms that TaRhTe4 is
isostructural to TaIrTe4. We show that all these compounds are metallic with
diamagnetic behavior. Ta$_{1.26(2)}$Ru$_{0.75(2)}$Te$_{4.000(8)}$ exhibits an
upturn in the resistivity at low temperatures which is strongly field
dependent. Below $T \approx 4$K we observed signatures of the superconductivity
in the TaIr$_{1-x}$Rh$_{x}$Te$_4$ compounds for $x = 0.92$. Magnetotransport
measurements on all samples show weak magnetoresistance (MR) field dependence
that is typically quadratic-in-field. However, for TaIr$_{1-x}$Rh$_{x}$Te$_4$
with $x\approx 0.78$, the MR has a linear term dominating in low fields that
indicates the presence of Dirac cones in the vicinity of the Fermi energy. For
TaRhTe$_4$ series the MR is almost isotropic. We have performed electronic
structure calculations for isostructural TaIrTe$_4$ and TaRhTe$_4$ together
with the projected total density of states. The main difference is appearance
of the Rh-band close to the Fermi level.
