| 摘要 |
A radio frequency input circuit of tuner is provided to prevent the signal interference due to the citizen band by removing the citizen band from the high frequency signal. A high pass filter(21) is comprised of a coil (L21) and a condenser (C21). The high pass filter passes through only the high pass of the high frequency signal received from the antenna(ANT). In the high frequency signal which the citizen band trap(22) is filtered from the high pass filter, the frequency of the citizen band is removed. The citizen band trap is comprised of a condenser (C23) and a coil (L22). The high frequency signal trapped in the citizen band trap is switched by a switching unit(23). The switching unit is comprised of a switching diode (D22). A low noise amplifier(24) amplifies the high frequency signal from which the citizen band is removed. The low noise amplifier is comprised of the transistor. The loop through(26) outputs the high frequency signal separated from the balloon to the external instrument. A zero power circuit(27) outputs the high frequency signal outputted from the high pass filter to the loop through. |
