Multichannel Crystal Control of VHF and UHF Oscillators

Single-crystal control of a multiplicity of uhf channel frequencies is obtained by periodic phase control of a variable oscillator. Its output consists of a spectrum of harmonically related frequencies. The bandwidth of the spectrum envelope can be kept so narrow that the amplitude of any single desired frequency of the very large number of available ones is emphasized up to 40 db over the amplitudes of the adjacent harmonics. Suppressions of the undesired frequencies in this order of magnitude are obtained in oscillators which cover a frequency range of from 250 to 900 mc and are simultaneously excited at a crystal-controlled fundamental frequency in the range of from 1 to 10 mc. Thus, utilizing one single triode this uhf oscillator may put out any desired one of a very large number of crystal-controlled frequencies. It is continuously tunable over a wide frequency range, acting as though it were electronically detented.