Some of you heard me enthusiastically describe the “QMX+” transceiver recently on one of our Wednesday evening radio nets. I’m excited about this rig for many reasons and wanted to share “why” with the check-ins that night because I just ordered mine. Now this is a QRP rig (transmits 3-5 watts), but don’t let that scare you off because it has every other feature of the of the multi-hundred $$ YeaComWood rigs we hear about all the time, PLUS some that only one other (Flex Radio) has so far – Polar Modulation, and I’ll get into that in just a moment.
The QMX+ all-band HF transceiver is small, light and appropriate for the bench or field. It has virtually every mode imaginable built into its firmware straight out of the box and is constantly being improved with more as time goes by since its intro last year this time. That’s CW, SSB, AM, WSPR & digital modes. There’s a new feature that a developer created for this open architecture allowing for an amazingly powerful 5-inch external spectrum display. The designer, Hans Summers G0OUPL, cooperatively-yet-independently developed the newest modulation scheme in Amateur Radio called Polar Modulation and implemented it in his QMX+ rig. As overviewed in QST magazine last year, and in a linked YouTube below, this mode enables super efficient linear transmissions – in the 90% range – such that classical heatsinking of finals is hardly necessary … Nearly every watt produced is sent out the coax!
One can purchase this all-band, full-featured kit for $125, or fully assembled and tested for an additional $60. It’s a wonderful POTA rig, or one for the bench. I will be selling off my $$$ Elecraft K3 once the QMX+ is built … It has everything I need in a modern transceiver. Check out the specs and links below to see for yourself. And you know that my lab is always open for anyone to visit to assemble kits here and/or test things out, so how can you go wrong?!
73, George N2APB
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QMX+ Feature Summary:
The QMX+ is a feature-packed, high performance, 160-6m 3-5W CW, Digi and SSB-modes transceiver kit (or assembled radio) from QRP-Labs. It including embedded SDR receiver, 24-bit 48 ksps USB sound card, CAT control, synthesized VFO with TCXO reference, CR2032 battery backed RTC, and internal GPS option. QMX+ may be used in CW modes standalone, or with a single USB cable to a PC for digi mode operation, or SSB (USB/LSB). QMX+ also incorporates standalone CW, FSKCW and WSPR beacon functionality (no PC connection required).
List of Features:
- Full 160m to 6m band coverage
- CW, FSK Digi, and SSB (USB/LSB) modes
- All features of QCX+ (VFO A/B/Split, RIT, Message and frequency memories, beacon, keyer, etc)
- 3-5W output at 12V supply (can be built for 3-5W at 9V supply)
- SWR bridge built in
- Internal RTC powered by the common CR2032 coin cell battery (battery not included)
- Single signal digi mode transmission (zero unwanted sideband, zero residual carrier, zero intermodulation distortion)
- Solid-state band switching and transmit/receive switching under CAT control
- High performance embedded SDR SSB receiver with 60-70dB of unwanted sideband cancellation
- Built-in 24-bit 48ksps USB sound card
- Built-in USB Virtual COM Serial port for CAT control
- Si5351A Synthesized VFO with 25MHz TCXO as standard
- Easy to build single-board design, Professional quality 6-layer, through-hole plated, silk-screen printed PCBs
- All SMD components factory assembled
- Connectors: 2.1mm power barrel connector, USB-C (for audio and CAT control), BNC RF input/output, 3.5mm jacks for audio out, paddle/GPS/mic/PTT in, and PTT out
- Built-in test signal generator and testing tools
- GPS interface for frequency calibration, real time clock and location (internal WSPR beacon)
- IQ output mode for use with SDR software
- Switched mode regulators Receive current 80mA, Transmit current 1.0-1.1A for 5W output with 9V supply (around 0.7A for 5W with 12V supply).
- Internal microphone ready for the future SSB firmware
- 11 GPIO ports including a 3.5mm stereo jack socket on the rear panel labelled “AUX” that may be configured as a serial port
- Optional aluminium extruded cut/drilled/laser-etched black anodized enclosure
- Weight: 578 grams including enclosure
QRP Labs webpage for their QMX+ Transceiver (available as kit $125, or assembled $185)
YouTube Overview of Polar Modulation High performance and efficient SSB at low cost — This lecture introduces the concept of polar modulation SSB, along with the story of the practical implementation of polar modulation SSB in the QRP Labs QMX and QMX+ transceivers. The significant benefits of polar modulation will also be discussed: higher efficiency, lower cost, higher performance.
Bringing SSB to the QMX — An overview of the QMX+ design and some of its unique and powerful features (e.g., self test, built-in instrumentation and calibration) that set it apart from other radio designs and enable the QMX+ to be easily assembled and brought ‘online’.
ARTICLE — The accompanying article is a 33-page PDF which you can DOWNLOAD HERE, and it contains a lot more details that are referred to in the presentation.
