Frequency characteristics in the case of resonance at self-oscillation harmonics

Theoretical and experimental results are presented on the frequency characteristics of a Thomson oscillator coupled inductively with a resonance circuit whose frequency is close to the harmonic frequency. It is shown that the frequency dependence in the case of locking at the harmonic frequency differs in character from that in the case of locking at the fundamental tone; the difference corresponds to an additional phase shift of pi/2. Mechanisms leading to an asymmetric frequency curve are examined.