Tuning circuit arrangement

A circuit for adjusting a tuning circuit, the tuning circuit including at least one resonant circuit composed of a variable inductance and a variable capacitance constituted by at least one voltage-variable tuning diode, one side of the resonant circuit being connected to a point at circuit ground potential and adjustment of the resonant circuit being effected by changing the resonant circuit inductance and the resonant circuit capacitance, with changing of the resonant circuit capacitance being effected exclusively by varying the tuning voltage of the tuning diode, the tuning circuit further including a source of a variable tuning potential which is variable over a range between maximum and minimum extreme values, each extreme value being different from the circuit ground potential, and said circuit for adjusting comprising at least one adjustment potentiometer connected between a point of said source providing the variable tuning potential and a point of said source permanently providing one of said extreme values, said potentiometer having an adjustable tap connected to provide the tuning voltage for said tuning diode.