It is basically just a very simple oscillator utilizing a hand full of standard parts. None of the component values are critical. Pretty much any transistor will work in this circuit. I included a HC-18 socket on my PCB for a fast turnaround time while selecting crystals. The output of the oscillator can be connected to a frequency counter to determine the crystals exact frequency.
One word of advise. Be careful to not hold the crystal too long between your fingers before performing the test. The body heat will alter the resonance frequency of the crystal and falsify the result.
Westerhold, S. (2012), "Simple oscillator as crystal tester". Baltic Lab High Frequency Projects Blog. ISSN (Online): 2751-8140., https://baltic-lab.com/2012/08/simple-oscillator-as-crystal-tester/, (accessed: October 3, 2023).
If you liked this content, please consider contributing. Any help is greatly appreciated.