The TFR group has recently employed radiofrequency powers in excess of 200 kW near the hydrogen cyclotron frequency in a predominantly deuterium plasma with some minority hydrogen. At low minority concentration, when ion-ion hybrid and hydrogen cyclotron resonance layers exist in the plasma, pronounced emissions have been observed at the hydrogen half-harmonics, accompanied by deuterium heating. It seems that the fast-wave pump decays parametrically into two short-wavelength deuterium Bernstein waves on the low field side of the cyclotron resonance layer, requiring a threshold power of less than 100 kW. The decay waves are eventually damped on the deuterium ions, thus heating them.