Radio tuner receives broadcasts and converts them into audio-frequency signals

Scheme Radio tuner FM

Radio tuner receives radio broadcasts and converts them into audio-frequency signals which can be fed into an amplifier driving a loudspeaker. FM tuner, AM tuner, DAB tuner, etc. are types of radio tuner dealing with transmissions using different methods of modulation.

The term tuner can mean either part of a radio receiver or a standalone component of an audio system, to be connected to a separate amplifier. The verb tuning in radio contexts means adjusting the radio receiver to receive the desired radio signal or station, out of all the radio signals the receiver can pick up.

Radio tuner FM

The simplest tuner consists of an inductor and capacitor connected in parallel. The capacitor is usually made to be variable (although the inductor can made variable it requires a more complex mechanism and is rarely used). This creates a resonant circuit which responds to an alternating current of one frequency. In general, radio makers will use a rule of thumb of 1.5 picofarads per metre wavelength.

Common inductance values are 4.1 mH for long wave, 370 mH for medium, and 130 nH for VHF (FM) between 88 and 108 MHz. In a superheterodyne radio the capacitor that tunes the "tank" will be ganged with another; this alters the local oscillator to provide a constant intermediate frequency. Combined with a detector, also known as a demodulator, it becomes the simplest radio receiver, often called a crystal set.

Most of the top end audio tuner models were designed and manufactured to receive only the FM broadcast band. As FM became more popular, the limitations of AM became more apparent, and the primary listening focus, especially for stereo and music broadcasting. The bulk of tuners made for the market, however, were AM/FM design, especially in the 1980s and 1990s. Few companies even manufacture dedicated FM or AM/FM tuners now, as these bands are most often included in a low cost chip for A/V systems, more as an afterthought, rather than designed for the critical FM listener. The FM aficionado must really look to the classic tuner models and either rebuild or upgrade the unit to satisfy demanding FM listeners. A few 1970s tuners feature now-deprecated Dolby noise reduction for FM broadcasts.