100Mhz-vhf-crystal-oscillator

  
Diagram shows a 100MHz oscillator operating on the fifth harmonic. Again to maintain the transistor`s gain, note the increase in the collector`s load resistance Rl because of the increase in the quartz crystal`s internal series resistance R5. C3 is needed at frequencies above 50 MHz to tune out the shunting effect of LLon Rl, to maintain a high load resistance for the transistor and get enough gain for oscillation.
100Mhz-vhf-crystal-oscillator - schematic

The equivalent series RLCL load across the crystal is 8.2ohm (RL) and 200 pF (CL)·




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