| 摘要 |
PURPOSE:To prevent the system from being decided at a fault even when an overcurrent flows due to short-circuiting of a cable or mis-wiring by inserting a switching element cutting off a current limit element between an overcurrent detection section and the current limit element. CONSTITUTION:A power supply line supplying a DC power supply to an outdoor device is coupled to an output terminal 12 via an overcurrent detection section 9, a current limit element 10 and a reverse flow preventing diode 11 and coupled further to a low noise amplifier and a down-converter 3 via a coaxial cable 13. Further, a voltage amplification and switching element 14 is coupled between the overcurrent detection section 9 and the current limit element 10, and if overcurrent takes place, a transistor (TR) of the overcurrent detection section 9 is turned on to turn on the switching element 14. Thus, the TR constituting the current limit element 10 is turned off to cut off the supply of the DC power supply. Thus, even when an overcurrent flows due to short-circuiting of a cable or mis-wiring, it is not decided as the fault of the system.
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