Drift free TV tuner with gyromagnetic filler - has temp. characteristics of filter resonance and oscillator frequencies aligned for mutual compensation

摘要

The tuner unit is for TV signals, and converts the signal received by the aerial to a constant intermediate frequency. The first frequency changer (4) has a tunable oscillator and has its output fed to a gyromagnetic filter (8) and thence to a second frequency changer (10) with a fixed frequency oscillator (12). In order to avoid drift of I.F. resonance with change of temperature, the two oscillators and the gyromagnetic filter resonance are designed to have similar temperature change characteristics, whilst remaining within the passband of the filter.