Circuit arrangement for a wide-band VHF-UHF television double superheterodyne receiver

摘要

The signal transmission lines in a double conversion stage for a double superheterodyne VHF-UHF television receiver are mainly constructed of unbalanced circuits rather than balanced circuits. The circuit arrangement comprises a wide-band amplifier for receiving the incoming carrier frequency, first and second frequency conversion stages, and an intermediate frequency amplifying stage, connections between the wide- band amplifier and the first frequency conversion stage, as well as connections between the second frequency conversion stage and the intermediate frequency amplifying stage are achieved by means of unbalanced circuits. Each of the first and second frequency conversion stages comprises a mixer constructed of a single balanced circuit, a local oscillator and an unbalanced/balanced conversion circuit interposed therebetween. A filter means, having a band-pass filter, and a low-pass filter interposed between the first and second frequency conversion stages effectively blocks spurious signals.