QRP Labs QMX Assembly Manual

Introduction to the QMX

The QRP Labs QMX is a high-performance, five-band 5W CW and Digital modes transceiver. It features CAT control and a built-in USB sound card, making it a versatile tool for amateur radio enthusiasts. This manual provides detailed instructions for assembling the QMX, including component identification, soldering tips, and final checks.

Key features of the QMX include:

• Five-band operation (80m to 10m options available)
• 5W output power (9V or 12V supply options)
• Clean signal output with zero residual carrier
• Sunlight-viewable LCD display
• Built-in SWR metering and protection
• Lightweight design
• Solid-state filters and switching
• High-performance embedded SDR receiver
• Built-in USB sound card and Virtual COM port for CAT control
• High-precision Si5351A synthesized local oscillator
• Built-in signal generator, configuration, and analysis tools
• Iambic keyer and on-screen S-meter
• CW decoder and fast break-in capability
• Beacon mode and GPS interface
• Lifetime free firmware upgrades
• SMD components pre-installed

This assembly manual is essential for a successful build. Please read all instructions carefully and follow them step-by-step. Attention to detail is crucial due to the compact nature of the QMX design.

Assembly Guidelines

The QMX kit includes pre-assembled SMD components, simplifying the building process. However, it is important to follow general kit-building recommendations:

• Work in a well-lit area with minimal distractions.
• Observe Electrostatic Discharge (ESD) precautions, as some semiconductors are sensitive.
• Use a jeweler's loupe for inspecting small components and soldered joints.
• A fine-tipped, high-power soldering iron (e.g., 60W) is recommended.
• Ensure good, clean solder joints, especially for grounded components.
• Be careful when soldering and clipping component leads to avoid damaging nearby SMD components.
• Remember to install diodes correctly oriented.
• Check all solder joints with a loupe after soldering.
• Install connectors squarely and ensure they are well-seated.
• The QMX is supplied without firmware. You must install the latest firmware after the first power-up, as described in section 2.33.

The manual also details the 6-layer PCB structure, including layer functions and via types. It emphasizes the importance of not drilling into the PCB and provides guidance on breaking out the various boards from the main panel.

Important Notes

• Ensure you decide on the 9V or 12V operation at the beginning of the assembly process.
• Operation at more than 5W output is not recommended and may lead to overheating.
• When using a 12V supply, a modified transformer winding (3:2 ratio) is recommended for optimal performance and to prevent overheating.
• Take care when handling the 3D printed parts and installing them to protect delicate components.

Resources

For further information and support, refer to the QRP Labs website for additional resources and community forums.