| 摘要 |
PURPOSE:To execute the coarse adjustment of tuning based upon a first frequency and to execute the fine adjustment of a tuning based upon a second frequency by obtaining the first frequency to beat down an intermediate frequency and the second frequency lower than the first frequency. CONSTITUTION:A first oscillating frequency foscl(63.75 MHz) is supplied from an oscillating device 5 to a first mixer 6, and then, an IF signal is beaten down and supplied to the 1/10 frequency dividing circuit 8 of a next step. A second oscillating frequency fosc2 (59.25 MHz) is supplied to a second mixer 7 and the IF signal is beaten down. When the IF signal is a regular value, a first frequency f<1> outputted from a first mixer 6 comes to be 5 MHz and a second frequency f<2> outputted from a second mixer 7 comes to be 500 KHz. When the IF signal is in the scope of 58.75+ or -5MHz, in such case while the output of wind comparators 12a-12d of a fine tuning adjusting part B is detected so as to be in the scope of 58.75+ or -0.5 MHz, a tuning voltage is adjusted, and in the same way, the tuning voltage is adjusted so that the IF goes into the scope of 58.75+ or -0.2 MHz.
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