This small high quality FM receiver is built around the TDA7000 IC. The TDA7000 consists of a local-oscillator and a mixer, a two stage i.f. filter followed by an I.f. limiter/amplifier, a quadrature f.m. demodulator and an audio muting circuit controlled by the I.f. waveform correlator. In a conventional portable radio, limiting at a low r.f. input level would cause instability because of higher harmonics of the clipped I.f. signal would be radiated to the aerial. With the low I.f. of 70kHz as used in the TDA7000, the radiation is negligible. The audio signal is amplified to about 1 watt by the U2822B amplifier.
Requires a speaker.
(MB090) |
