Frequency converter, especially CATV converter

A CATV converter of a dual frequency conversion type, comprising an input terminal and an output terminal, an input stage (31) for tuning to a desired channel of CATV signals supplied to said input terminal (21), a variable frequency local oscillator stage for generating a first local oscillator signal, a buffer stage for said first local oscillator signal, a first mixing stage (33) connected to said local oscillator stage and to said input stage (31) for converting said selected CATV signal into a UHF-IF signal using said first local oscillator signal, a first amplifier stage (35) connected for amplifying and selectively conditioning said UHF-IF signal provided by said first mixing stage (33), a fixed frequency oscillator stage (41) for generating a second local oscillator signal, a second mixing stage (42) for converting said UHF-IF signal provided by said first amplifier stage (35) into a VHF-IF signal using said second local oscillator signal of a certain frequency, a second amplifier stage (44) connected for amplifying said VHF-IF signal provided by said second mixing stage (42), and an output signal control stage (45, 46) connected for attenuating and controlling said VHF-IF signal provided by said second amplifier stage (44) and for supplying said attenuated VHF-IF signal to said output terminal (22), said converter further comprising shielding compartments in which said stages between said input and output terminals are disposed, said shielding compartments comprising a frame base and intersecting partition walls within said frame base, and wherein said shielding compartments include separate shielding compartments (32, 55) for the respective local oscillator circuits, and a shielding compartment (37) for said buffer stage for said first local oscillator signal, a shielding compartment (59) formed by dual shielding walls, and a coupling compartment (54) for said UHF-IF signal, said last mentioned three compartments (37, 59, 54) being interposed between said compartments for said variable frequency local oscillator stage (32) and said fixed frequency local oscillator stage (41) for enhancing the isolation between said input and output terminals (21, 22), and wherein said input and output terminals are disposed apart from each other on one side of said frame base which comprises a front side and d.c. power line terminals disposed on said front side, whereby a wiring system for said d.c. power line terminals is separated from a wiring system of said input and output terminals by conductive partition plates.

A CATV converter of a dual frequency conversion type comprising an input terminal and an output terminal, an input stage (31) for tuning to a desired channel of CATV signals supplied to said input terminal (21), a variable frequency local oscillator stage for generating a first local oscillator signal, a buffer stage for said first local oscillator signal, a first mixing stage (33) connected to said local oscillator stage and to said input stage (31) for converting said selected CATV signal into a UHF-IF signal using said first local oscillator signal, a first amplifier stage (35) connected for amplifying and selectively conditioning said UHF-IF signal provided by said first mixing stage (33), a fixed frequency oscillator stage (41) for generating a second local oscillator signal, a second mixing stage (42) for converting said UHF-IF signal provided by said first amplifier stage (35) into a VHF-IF signal using said second local oscillator signal of a certain frequency, a second amplifier stage (44) connected for amplifying said VHF-IF signal provided by said second mixing stage (42), and an output signal control stage (45, 46) connected for attenuating and controlling said VHF-IF signal provided by said second amplifier stage (44) and for supplying said attenuated VHF-IF signal to said output terminal (22), said converter further comprising shielding compartments in which said stages between said input and output terminals are disposed, said shielding compartments comprising a frame base and intersecting partition walls within said frame base, and wherein said shielding compartments include separate shielding compartments (32, 55) for the respective local oscillator circuits, and a shielding compartment (37) for said buffer stage for said first local oscillator signal, a shielding compartment (59) formed by dual shielding walls, and a coupling compartment (54) for said UHF-IF signal, said last mentioned three compartments (37, 59, 54) being interposed between said compartments for said variable frequency local oscillator stage (32) and said fixed frequency local oscillator stage (41) for enhancing the isolation between said input and output terminals (21, 22), and wherein said second mixing stage (42) and said fixed frequency local oscillator stage (41) are formed as a self-oscillation mixing circuit comprising a dual-gate FET and a SAW resonator disposed in a shared compartment, said dual-gate FET having a first gate electrode used to receive said UHF-IF signal and a drain electrode used to provide said output VHF-IF signal.