| 摘要 |
PURPOSE:To facilitate optimum tuning, by controlling a voltage control amplifier, which is connected to an AFC circuit, by a DC voltage proportional to a local oscillation frequency. CONSTITUTION:A voltage control amplifier 8 is connected to a low-pass filter 7 which takes out a DC voltage proportional to a detuning frequency, and the output of this voltage control amplifier 8 is led to a local oscillating circuit3. A frequency- voltage converter 9 is connected between the local oscillating circuit 3 and the voltage control amplifier 8, and the degree of amplification of the voltage control amplifier 8 is controlled by a DC voltage proportional to the local oscillation frequency. That is, the gain of the voltage control amplifier 8 is changed in accordance with a receiving frequency to make the control range of the frequency control constant when the receiving frequency is any of frequencies between the upper limit and the lower limit. |
