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Three types of HF and VHF crystal controlled transistor oscillators are experimentally studied to assess their frequency shift bandwidth and stability properties. The capacitance bridge oscillator exhibits a bandwidth under certain circuit conditions of 0.1 per cent of center frequency, with amplitude modulation of 1 db, but degraded frequency stability. Combining this oscillator with another exhibiting superior stability in the low VHF band results in a hybrid oscillator circuit in which frequency can be shifted 0.02 percent with good power regulation. Frequency stability is 0.46 ppm/ and 3 ppm/10 per cent change in supply voltage. Most of the experiments were conducted at 35 Mc, but higher order modes to 150 Mc were also investigated.