Tuner

This article should be divided into sections by topic, to make it more accessible. Please help by adding section headings in accordance with Wikipedia's style guidelines. (October 2009)

This article may require cleanup to meet Wikipedia's quality standards. Please improve this article if you can. (September 2009)

A 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 is used both for part of a radio receiver which also contains an amplifier section and for a boxed piece of equipment to be connected to a separate amplifier.

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 milliHenries for long wave, 370 microHenries for medium, and 130 nanoHenries 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. Standalone audio stereo FM tuners are sought after for audiophile and TV/FM DX applications, especially those produced in the 1970s and early 1980s, when performance and manufacturing standards were among the highest. In many instances the tuner may be modified to improve performance. A growing hobby trend is the electronics specialists that buy, collect and restore these vintage FM or AM/FM audio tuners. The restoration usually begins with replacing the electrolytics (capacitors) that age over time. The tuner is outfitted with improved tolerance and better sounding upgraded parts. Prices have increased relative to the increasing demand for the older audio tuners. Those with the most value are the best sounding, most rare (collectible), the best DX capable(Distance Reception)and the known build quality of the component, as it left the factory.^[1]

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.

See also

• Receiver (radio)

Notes