| 摘要 |
PURPOSE:To improve a transmission characteristic by inserting a resistor in series between a signal changing-over switching diode and a high frequency earthing capacity. CONSTITUTION:An external signal inputted from an ANT-IN passes through an RFAMP circuit 1, and one of it is outputted to a VTR-OUT at a distribution transformer T1, and the other is outputted through switching diodes D1 and D2, and is synthesized with an RF converter signal from an RF converter 2, then being outputted to an RF-OUT. The circuit is equipped with a BS circuit which operates the switching diodes D1 and D2, and a resistor R0 is inserted in series between the switching diode D2 and a high frequency earthing capacitor C2. When BS=12V, the switching diode D2 is turned on, and a load at a point A in the distribution transformer T1 becomes equal with the insertion resistor R0, and fluctuation in a load impedance in a mode switching time is scarcely recognized, and the fluctuation in the transmission characteristic to the VTR- OUT can be reduced.
|
