| 摘要 |
PURPOSE:To simplify the constitution for band changeover by utilizing the difference of impedance to a reception band to apply band changeover. CONSTITUTION:A mixer 3 is connected to a post-stage of the 1st high frequency input circuit 10 and a band changeover switching diode D22 is provided between the 2nd high frequency input circuit 20 and the said mixer 3. The output impedance of the 1st input circuit 10 is kept higher for the 2nd reception band signal and the output impedance of the 2nd input circuit 20 is kept lower for the 1st reception band signal. Thus, in throwing a band selection switch 5 to the 1st band AM, the diode D22 is turned off and the signal of the 1st input circuit 10 is inputted to the mixer 3. On the other hand, in throwing the said switch 5 to the 2nd band AIR, the diode D22 is turned on and the signal of the 2nd input circuit 20 is inputted to the mixer 3.
|
