Overloading and spurious responses in transistor FM tuners

A transistor, when used as a mixer in an FM tuner, will produce spurious responses that cause interference from other FM stations. The use of two mixer diodes in a balanced circuit to minimize this type of response is shown. Also described is a double-tuned circuit ahead of the r-f stage which will improve the spurious response ratio along with a decreased possibility of overloading the r-f amplifier.