K3ng Keyer — Schematic

Symptom: The keyer sends random dots and dashes when you turn on your transmitter. Cause: You forgot the 4.7k pull-up resistors on pins 2 & 3. Fix: Add resistors physically or enable INTERNAL_PULLUP in the code (though external resistors are better for RF immunity).

Similar to keying, PTT requires a transistor switch. Many K3NG schematics dedicate a separate pin (e.g., D13) for PTT. This allows the keyer to put the radio into transmit mode before the first dit—essential for QSK (full break-in) or semi-break-in operation. k3ng keyer schematic

The brain of the operation is usually an Arduino Uno for basic setups or an Arduino Mega 2560 for builders who want to enable memory-intensive features like LCD displays and full WinKey emulation. Symptom: The keyer sends random dots and dashes