Input selection arrangement for applying different local oscillator signals to a prescaler of a phase-lock loop tuning system

Apparatus, comprising:

• frequency divider means having an input terminal for dividing the frequency of a local oscillator signal applied to said input terminal;
• a first local oscillator for generating at a first output point a first local oscillator signal having a frequency in a first band of frequencies when enabled to operate;
• a second local oscillator for generating at a second output point a second local oscillator signal having a frequency in a second band of frequencies lower in frequency than said first band when enabled to operate;
• band selection means for selectively enabling said first and second local oscillator means to operate to generate respective ones of said first and second local oscillator signals;
• input means including reactive components coupled between said first and second output points and said input terminal;
• and
• configuration selection means coupled to said input means and said band selection means for selectively configuring said input means to form a first reactive network having a first frequency response characteristic for passing signals in said first band when said first local oscillator is enabled and configuring said input means to form a second reactive network having a second frequency response characteristic different from said first frequency response characteristic for passing signals in said second band and rejecting signals in said first band when said second local oscillator is enabled.