Modified G3UUR crystal testing and screening circuit

This circuit is based on the G3UUR crystal testing and screening circuit introduced in the ARRL manual, replacing the crystal with a DIP8 socket, adding an output BNC, and replacing the test switch with a 6mm self-locking key switch.

use

• The circuit is powered by an external 12v DC power supply, and the current is about 6mA during operation.

• Connect a digital multimeter to H1 to measure the DC voltage to determine the output signal strength.

• When H2 is powered off, connect a digital multimeter to measure the resistance value to determine the crystal ESR value.

  • S1 is closed, S2 is open
  • Insert the crystal under test into the DIP8 socket and measure the output signal voltage V1 on H1
  • When two crystals are connected in parallel (purpose of DIP8 socket) R7 is adjusted to get the same voltage on H1 as V1
  • Measure H2 after power off to get ESR

• Output BNC is connected to an oscilloscope to observe the output waveform and judge the quality of the crystal.