| 摘要 |
PURPOSE:To save the choke coil and to prevent abnormal oscillation, by supplying power supply to the amplifying element via the coil of 1/2lambda type tuning circuit. CONSTITUTION:The tuning circuit consists of the coils 22, 23 in direct connection, tracking capacitor 21 in parallel connection in high frequency, and varactor diode 21 in parallel connection in high frequency, and varactor diode 7. The inductance of the coil 23 is selected so that the parallel resonance frequency with the varactor diode 7 is lower than the UHF reception frequency band. Accordingly, this parallel resonance circuit shows capacitive at the UHF frequency band and forms the 1/2lambda type tuning circuit together with the tracking capacitor 21 and the coil 22. Thus, one end of the coil 23 is lower in potential and suitable for the direct coupling of the power supply. |
