An oven includes a cooking chamber configured to receive a food product and an RF heating system configured to provide RF energy into the cooking chamber using solid state electronic components. The solid state electronic components include power amplifier electronics configured to provide a signal into the cooking chamber via a launcher assembly operably coupled to the cooking chamber via a waveguide assembly. An isolation assembly is provided between the launcher assembly and the power amplifier electronics. The power amplifier electronics are controlled at least in part based on an efficiency parameter determined from a forward power value and a reflected power value that are each measured after the isolation assembly.