We report on the radiofrequency (RF) dynamics of intracavity frequency doubled Nd : YVO4 /KTP laser operating in mode-locked regime. For a certain parameter range, the second harmonic is weakly modulated while the fundamental output remains not modulated. The effect manifests itself as weak sidebands of the beat note signal and a low-frequency signal (order of 50–100 MHz) in the RF spectrum. Applying additional cavity length modulation via a piezoelectric transducer leads to occurrence of a squared Lorentzian shaped spectrum for the weak sidebands and low-frequency signal but the beat note is not affected. We propose that this regime is an evidence of the phase bounding effect in the mode locked state.