Base Bias Tuned VFO

VE7BPO describes the interesting article called Base Bias Tuned VFO. The VFO is based on the common base colpitt's oscillator and tries to change the bias voltage. The 2N3904 transistor is used for the VFO.

I made the VFO with this schematics but the capacitor 220pF is not good for my built VFO. Therefore, the capacitor 220pF and L1 have been changed to make the oscillation. My VFO has got the 7MHz band. Since the VFO is the L/C oscillator, the stability should be managed with the L/C value.