Morse Code Practice Oscillator Type C Powered CW Trainer with 3.5mm Key and LED Audio Feedback

K4 Key Trainer CW — compact practice oscillator for Morse code training with 3.5mm key input and Type C power What it does Provides a compact, portable oscillator that generates a clear Morse code tone for practice with a vertical hand key. Accepts a standard 3.5mm key plug for direct connection to most singlelever vertical hand keys. Powered by a Type C source for convenient use with modern power banks, laptop USBC ports, and USBC wall adapters. Gives immediate feedback through an audible buzzer and a visible LED rhythm indicator to help you monitor dot and dash timing. Why you need it Improves timing and send accuracy by converting key presses into a stable audio tone and synchronized LED pulses. Eliminates the need for larger transceivers or bench equipment when practicing sending skills. Lets you practice anywhere thanks to its low power requirement and Type C compatibility. Key benefits and features Compatibility: 3.5mm key interface works with standard vertical hand keys designed for singlelever CW practice. Power flexibility: Type C power input allows safe, convenient operation from common USBC power sources. Immediate feedback: Buzzer provides audible confirmation while LED rhythm shows signal timing visually. Portable design: Small and lightweight for practice at home, in the field, or at club meetings. Simple setup: Plug the key into the 3.5mm jack, connect a USBC power source, and start practicing. Performance highlights Stable oscillator output suited for learning and refining sending technique. Synchronized buzzer and LED ensure consistent timing cues for both hearing and sight learning styles. Low power draw for long practice sessions using portable power banks. Practical use scenarios Home practice: Use a USBC wall adapter to power the trainer at a desk or workbench for regular sending drills. Field or portable operation: Power from a USBC power bank during outdoor events, field days, or portable radio outings where a full transceiver is not practical. Club training sessions: Provide quick, shareable practice stations for learners to work on timing and rhythm without setting up radio equipment. What to expect in use Straightforward connection and operation for immediate practice. Clear audio tone and visible LED pulses that correspond to your keying for real time correction. A compact solution that supports focused skill development for beginners and experienced operators refining timing. Includes K4 Key Trainer CW unit with 3.5mm key interface and Type C power input, builtin buzzer and LED rhythm indicator. Simple, reliable, and designed for practice: the K4 Key Trainer CW helps you develop consistent Morse code sending skills in a compact, portable package.