Overview:
The Open CW Keyer MK2 is a small, finished kit housed in a blue aluminum case. The unit ships with the assembled keyer and a single cable; no other accessories are included. The enclosure and electronic components combine to create a compact device measuring approximately 50 x 58 x 24 mm.

Core capabilities:
This keyer supports adjustable sending speed from 1 to 999 WPM. It provides a PTT output whose lead, tail, and hang times can be tailored. Programming and host interfacing are handled via a USB "line interface," and two onboard memories can store macros for rapid message sending. A front-panel speed potentiometer is provided, and speed may also be changed by command.

Keying modes and timing:
Multiple keying modes are supported, including Iambic A and B, straight key, ultimatic, and bug emulation. Additional timing options include Farnsworth spacing, Dah-to-Dit ratio adjustment, keying compensation, and weighting. Sidetone frequency is adjustable and can be disabled when the paddle is repurposed for menu navigation or memory programming. Modes such as QRSS and HSCW beacon/fox are available for specialized transmissions.

Practice, stacking, and interfacing:
The firmware includes practice tools (callsign receive and send practice) and supports memory stacking. It can emulate K1EL Winkey 1.0 and 2.0 protocols for logging and contest software integration. Serial access via a terminal program (for example, Putty or similar) allows keyboard-style control and advanced configuration.

Reliability and customization:
Non-volatile storage preserves most settings between power cycles. A "Dead Operator Watchdog," autospacing/wordspace adjustment, pre-configured and custom prosigns, and modular code design let users enable or disable features and simplify firmware modifications.

Package contents and notes:
Included: 1 x Open CW Keyer MK2 KIT, 1 x cable. No other items are supplied. Because of screen and lighting differences, the product color may look slightly different in photos. Physical measurements can vary by ±1–3 cm.

VerdictA compact, feature-packed CW keyer finished in an aluminum shell that gives hobbyists plenty of flexibility: wide speed range, PTT control with adjustable lead/tail/hang, USB programming, and support for multiple paddle and keying modes. It’s a strong option if you want a highly configurable keyer and don’t mind doing a little setup or firmware work. Some users report reliability or configuration

John II 1/5

Looks great but failed to key my radio

It arrived quickly and the blue aluminum case is attractive, but I couldn't get it to key my transceiver. The device itself powers up and emits an error beep whenever I send data. I verified the virtual serial port, updated drivers, and tried different baud and port settings. I also reflashed the board and loaded alternative sketches (tried both K3NG and the ka-keyer sketch), but every attempt produced the same error tone and no transmit action. My paddles work directly on the radio, so the radio side is fine. I wanted a plug-and-play experience, but this unit required more troubleshooting than I could resolve.

reliability guru 5/5