Phase Shift in Radio Transmitters

This paper describes a type of distortion present to some degree in most modulated transmitters. A method of measuring phase shift using the cathode ray oscillograph is shown. Also oscillograms are shown which were taken on a short-wave broadcast transmitter. It is shown that the detuning of tank circuits causes phase shift. The tank circuit of the modulated stage is especially susceptible in this regard. Other causes of phase shift are also shown. The effects of phase shift are treated mathematically, the most serious result being the creation of adjacent channel interference. The amplitude of the second order side band is roughly one per cent of the first order side band per degree of phase shift.