K3ng Keyer Schematic [2021] -

Whether you are printing the k3ng_keyer_schematic.pdf to build a contest-grade station or just to understand how interrupts work, this design represents the pinnacle of DIY radio culture.

Start with the minimal build (Arduino + 2 resistors + 1 transistor + 2 paddles). Once you get a "dit" on the air, add the LCD. Then add the encoder. Then add the PS2 keyboard. The schematic supports it all. k3ng keyer schematic

Solder two 4.7k resistors from pins 2 and 3 to +5V. Solder your left paddle wire to Pin 2. Right paddle to Pin 3. Whether you are printing the k3ng_keyer_schematic

Some schematics show a 10kΩ resistor specifically for the straight key input (Pin 7). Straight keys are mechanical switches that bounce. The firmware handles debouncing, but the resistor ensures the logic level is valid. Section 3: The Output Stage – Don't Fry Your Arduino The biggest mistake new builders make is connecting Pin 9 (Key Out) directly to their radio's "CW Key" jack. Then add the encoder

For high-voltage tube transmitters (e.g., Johnson Ranger), you cannot use a 2N2222. The schematic allows for a 4N25 optoisolator . You bridge the Arduino side with a 330Ω resistor, and the transistor side connects directly to the tube rig's 150V key line.

Plug USB into Arduino. Done.