For amateur radio operators, the K3NG Arduino-based Morse code keyer is nothing short of legendary. Developed by Anthony Good (K3NG), this open-source project has become the gold standard for modern keyers, offering features that rival—and often surpass—commercial units costing hundreds of dollars. From contest-grade memory functions, PS2 keyboard support, and Winkeyer emulation to touch interfaces and Bluetooth control, the K3NG keyer can do it all.
Analog pin A0 connected to wiper of 10k pot. The repack reminds: “If not used, comment out #define speed_pot_pin” in the firmware.
Wire the paddles and button to close to GND when pressed. The code uses internal Arduino pull-up resistors, but adding external 10k-ohm pull-up resistors improves stability in high-RF environments. Add 0.01µF ceramic capacitors from each input line to ground to filter RF noise. 3. Rig Keying Circuit (Optoisolator) k3ng keyer schematic repack
House the completed board in a shielded aluminum project box. Connect the enclosure chassis to the circuit ground to form a Faraday cage.
Best for the "shack mega-station." Offers massive program space and dozens of I/O pins, allowing you to run an LCD, full keyboard interface, rotary encoders, and multiple transmitter keying lines simultaneously. 2. The Repacked Master Schematic Blocks For amateur radio operators, the K3NG Arduino-based Morse
: Use an opto-coupler (like a 4N25) or a transistor to isolate the Arduino from the radio's keying line to prevent damage from high voltages. Potentiometer (Speed)
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The K3NG keyer is one of the most rewarding projects in amateur radio. It transforms a $5 Arduino into a professional-grade contest companion. But its potential has been bottlenecked by schematic fragmentation.
For the ultimate standalone experience, adding an LCD or OLED display tracks your WPM, memory slots, and sent text. Highly recommended to save pins. VCC to 5V GND to GND SDA to Arduino A4 (on Nano/Uno) or Pin 20 (on Mega) SCL to Arduino A5 (on Nano/Uno) or Pin 21 (on Mega) 3. Pin Mapping Reference Guide