| 摘要 |
An RF switch comprises a housing in which a board is contained. To the board, two input ends connected respectively to an F-connector and an RCA plug and one output end connected to an antenna terminal of a TV receiver by an F-plug are connected. On the board, high-pass filters connected in a cascade fashion are formed, of which input is connected to one input end connected to the F-connector. The filter in each stage is earthed at the output side thereof through corresponding switching transistors. When a power switch of a main unit of a picture processing apparatus is turned on, a superposed signal of a DC signal and an RF signal is given to the remaining input end from the main unit through the RCA plug and a coaxial cable. In the RF switch, the DC signal is taken out from the superposed signal, thereby respective switching transistors are turned on. Accordingly, a TV signal from a TV antenna is flown into the earth, while the RF signal from the main unit it given to the output end through a diode biased in a forward direction by the DC signal. When the power switch of the main unit is in "off", the high-pass filters will not be inactivated and the TV signal from the TV antenna is thus given to the output end.
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