| 摘要 |
PURPOSE:To trap disturbing frequency components by connecting a capacitor between respective intermediate points connecting the 1st and 2nd band tuning coils in primary and secondary tuning circuits. CONSTITUTION:A tuning coil T has a primary series circuit consisting of two band tuning coils L1, L2 and a secondary series circuit consisting of two band tuning coils L3, L4. Switching diodes D1, D2 are connected to an intermediate point P1 connecting the tuning coils L1, L2 and an intermediate point P2 connecting the tuning coils L3, L4 respectively. Varactor diodes D3, D4 are connected to the tuning coils L1 and L3 in parallel respectively. A capacitor C31 is connected between the connection points P1 and P2. The capacitor C31 traps disturbing frequency components without destroying the symmetry between the primary and secondary tuning circuits to reduce influences on the characteristics of a double tuning circuit. |
