A dielectric-free slotted waveguide fast wave coupler (SWFWC), operating in the lower hybrid range of frequencies, has been used to drive current on the Versator-II tokamak. Up to 35 kW of radiofrequency at 2.45 GHz has been radiated into plasmas with electron densities of 2 × 10l2 cm−3 ≤ e ≤ 1.2 × 1013 cm−3 and a magnetic field of Btor = 1.0 T. When the coupler was flush with or beyond the limiter, the radiating efficiency improved linearly with increasing rig. For electron densities e ≥ 5 × 1012 cm−3, the current drive efficiency was similar to that of the slow lower hybrid wave; however, at lower densities the efficiency of the SWFWC was reduced and it drove no current when e ≤ 2 × 10l2 cm−3. During bench tests, the antenna radiated >90% of its power in the fast wave polarization. These observations suggest that the SWFWC launched primarily fast waves. However, we do not exclude the possibility that, owing to weak single-pass absorption, a substantial fraction of the power may have been converted to slow waves within the plasma, and these waves may have been responsible for most of the driven current.