| 摘要 |
PURPOSE:To attain simplification and miniaturization of shield and to prevent deterioration of the characteristic due to heat by revising the oscillating frequency of an oscillator of a switching power supply circuit in response to the reception frequency of a tuner so as to avoid the effect of noise of a switching power supply onto a reception signal. CONSTITUTION:A frequency variable means 16 is controlled by an output of an oscillation frequency detection means 15 detecting the oscillation frequency of a local oscillation circuit 3 to control the oscillated frequency of the oscillator 11a of the switching power supply circuit 7. In this case, the oscillation frequency of the oscillator 11a of the switching power supply circuit 7 is changed so that the high frequency does not give effect on the reception frequency depending on the oscillation frequency of the local oscillation circuit 3, e.g., in a way that the reception frequency is an intermediate frequency between the 1st harmonic and the 2nd harmonic of the switching frequency. Thus, the shield of the switching power supply circuit 7 is simplified and miniaturization is attained and the heat is discharged excellently.
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