70MHz crystal oscillator

As shown in the figure, this is a 70MHz crystal oscillator circuit. It consists of a crystal oscillator, a buffer amplifier, a frequency-selective amplifier, etc. Its main function is to output a 70MHz baseband frequency signal after the weak signal output by the crystal oscillator passes through the amplifier circuit and then undergoes frequency-selective amplification.

Component selection:

Transistor VTl: 3DG5F, β≥100; VT2, VT3: G711D or 3DG5F, β=60～80; Quartz crystal SJT:

JA-72A-70MHz; color code inductors L4, L5: LX-3A-5.6μH. Other component parameter values ​​are marked as shown in the figure.