Tuners are waveguide components used to match the load impedance with the source impedance. They minimize the amount of reflected power, providing the most efficient coupling of power to the load. Richardson Electronics supplies both manual 3- and 4-stub tuners, electrical and auto tuners. Auto and electrical tuners utilize motorized tuning stubs electronically controlled remotely or by a microprocessor. Auto-tuners are generally used in applications where the load impedance varies significantly due to variations in the load.