This is a 35.3 to 10.7 MHz converter circuit. It converts the 35.3 MHz signal coming from a VHF/UHF tuner down to an FM tuner to decode the TV audio in FM quality. The IC being used (TBA120) is one of the most common components in radio and TV circuits. Although it was designed as an RF amplifier and FM demodulator, it can also be used for many other applications.