Band switching type video intermediate frequency wave circuit

Abstract

Abstract PURPOSE:To receive TV signals of plural different broadcasting types only by one receiver, by turning on and off between a bridge T type trap which is connected to the front stage of a surface wave filter and provided with a coil and the earth. CONSTITUTION:A bridge T type trap 4 provided with a coil L1 inserted on the earth side and a bridge T type trap 5 provided with a coil L2 and a resistor R2 inserted on the earth side are connected between an connection terminal 1 to a tunner and a preamplifier 3 connected to the front stage of a surface wave filter 2. A switching diode D6 is connected between the common connection point of the coil L1 and the resistor R2 and the earth and the diode D6 is connected to a power supply through a switch SW1 and a resistor R3. A filter 4 has PAL- G type characteristics and the traps 4, 5 form NTSC type adjacent video carrier and sound trap respectively and receive a PAL-G type TV signal when the SW1 is ''off'' and an NTSC type TV signal in case of ''on''.

Inventors

• 👤 Haruichi Arai
• 👤 荒井　晴市

Bibliographic Details