Oscillator circuits for wide-range tuning

The design and operation of circuits to cover wide tuning ranges at ultra-high frequency, when used in conjunction with triode valves of the disc-seal type, are described in detail. The use of coaxial-line resonators to cover various tuning ranges between frequencies of about 300 Mc/s and 3750 Mc/s, and the practical difficulties encountered with such circuits, are discussed. Alternative forms of circuits which overcome most of the problems involved have been developed and details are given of oscillator units which cover wide ranges up to frequencies of the order of 1200 Mc/s.