| 摘要 |
PROBLEM TO BE SOLVED: To prevent a down converter to be used for frequency-converting a private incoming signal, which is frequency-converted by an up converter in a private CATV system into an original incoming signal, from transmitting a high-frequency noise generated by the operation of an internal circuit to a transmission line inside a building or to the side of a center device. SOLUTION: A shield board 45 is erected in the circumference of a high-frequency signal generating circuit 51, reference signal generating circuit 52 reference signal circuit 53 filter circuit 55, private incoming signal amplifier circuit 58, frequency-converting circuit 54 and incoming signal amplifier circuit 59 on a printed wiring board 50, where various function circuits constituting the down converter are assembled. In addition, the circuit 51 to be the generation source of a high-frequency noise, the circuits 52 and 53 and a power source circuit 75 arranged on a power source circuit substrate 70 are arranged at positions separated from the filter circuit 55, which is connected to respective terminals T1-T4, To and Ti. |
