| 摘要 |
PURPOSE:To prevent higher hamonics from entering a detector by closing a switch, provided to the UHF output terminal of SAW (surface acoustic wave) element 2, in UHF reception and by opening it in VHF reception. CONSTITUTION:On the reception of the UHF band, a DC voltage is applied to UHF band switch terminal 15 and diode 17 conducts to send the output of SAW element 2 to detector 3, the channel selection of the UHF band will be done. On VHF band reception, on the other hand, 0V is applied to UHF band terminal 15 and diode 17 turns off, so that even when higher harmonics of a local oscillation signal of the VHF band pass through the UHF band part of SAW element 2, they will never reach detector 3. |
