Noise Spectrum of Crystal Rectifiers

Studies of the noise spectrum of crystal rectifiers were made over a frequency range of 50 cycles to 1 megacycle. The circuits used in the analysis are described. It was found throughout the range that, regardless of the type of power applied to the crystal, the noise temperature varies inversely with the frequency. The noise in the audio range is always large; a noise temperature ratio of 10⁶is not uncommon. A mechanism responsible for the observed noise has not yet been suggested.