DIY Antennas, QRP, SDR & Ham Radio Projects from VU3DXR
Got dead crystals? Build a UJT tester to check them! Plus crystal-controlled FM & CW transmitter projects for ham radio DIYers
Stop guessing if your quartz crystals are dead or alive! Learn how to build a Simple UJT Crystal Checker circuit to test your components like a pro. This DIY guide includes a full schematic, 2N2646 UJT tips, and step-by-step instructions for quick troubleshooting.
Build a simple 40 m CW transmitter using a 2N2222 and 7 MHz crystal oscillator — a minimalist QRP design with keyed oscillator and low-pass filter for clean HF Morse transmission.
This crystal tester method lets you confirm a crystal’s “active” status by comparing its output to a known good crystal available
A crystal controlled FM transmitter is a radio frequency (RF) circuit that uses a quartz crystal oscillator to generate a stable, precise frequency for FM radio transmission. Unlike simple LC oscillator circuits, crystal-controlled transmitters offer superior frequency stability and accuracy, making them ideal for applications requiring consistent performance.