How to Get Uniform, Linear Tuning Dials with Nonuniform, Nonlinear Tuning Diodes

Applying hypersensitive capacitance diodes we are faced with a wide spread of different capacitance-vs-voltage characteristics. This leads to severe problems for the calibration of dials of AM-broadcast-receivers with tuning diodes of very high capacitance ratios. A frequency-to-voltage converter solves this problem. The frequency of the local oscillator of the tuner is converted into a linearly proportional dc-voltage by a simple circuit. This dc-voltage is indicated by a meter with a linear frequency scale.