[en] The first experiments to be performed with ICRF heating of DT plasmas are reported. ICRF heating of minority ions, tritium (second harmonic resonance), as well as direct electron heating are being performed during the DT phase of TFTR. RF power modulation and Fourier transform techniques are used to attempt to elucidate the competition between tritium second harmonic, direct electron, and ³He fundamental heating in DT plasmas. A significant fraction of the RF power has been found to couple to the tritium ions via second harmonic heating. Relevant RF coupling physics is investigated using ³He minority heating (43 MHz), H minority heating (64 MHz), and mode conversion (43 MHz, comparable densities of ³He and ⁴He) at a toroidal field of 4.5T