QRP Labs QMX
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| Frequency | Three versions: 80/60/40/30/20m, OR 60/40/30/20/17/15m, OR 20/17/15/12/11/10m. Select at purchase. |
| Bands | 5-6 bands (select version at purchase). QMX+ variant: 160-6m (12 bands incl. 60m and 11m). |
| TX power | 5 W (3-5W depending on band and supply voltage. Build for 9V or 12V (select when ordering). Safe supply 6-12V - do NOT use 13.8V, which will damage the radio.) |
| Modes | CW, digital (FT8, FT4, JS8Call, WSPR, RTTY, Olivia, most WSJT-X), SSB (USB/LSB) - official since May 2025 |
| Weight | 120 g (4.2 oz) - Approximate, without enclosure. Optional enclosure: 63×25×95 mm. |
| Connector | BNC |
| Year | 2023 |
| antenna | BNC |
| usb | USB-C (audio + CAT control — single cable to PC) |
| dc in | 2.1mm power barrel |
| audio out | 3.5mm (earphones — not speaker level) |
| paddle mic | 3.5mm (paddle, GPS, microphone, PTT — shared port) |
| ptt out | 3.5mm PTT output |
| power req | 6-12 VDC (built for 9V or 12V at order time). DO NOT USE 13.8V. RX ~80 mA. TX 1.0-1.1A at 9V for 5W, ~0.7A at 12V. |
CW, digital, and SSB in a shirt-pocket-sized, modestly priced kit. The embedded SDR has 60-70 dB sideband cancellation. It has fast, clean QSK break-in and a single USB-C cable for both audio and CAT control. Standalone CW works with good filters, and there is a WSPR beacon mode. SSB is produced by polar modulation. It is one of the more capable kits in its price class.
6-12 V only: a standard 13.8 V supply will damage it (the single most common way owners kill one). 3-5 W is QRP. It is a more advanced, tightly-packed build than the QCX-mini and the audio output drives earphones, not a speaker. SSB via the small electret mic port is functional but basic. Assembled units carry long waits, you commit to a band-version and a supply voltage at purchase, and the price has risen well above its original launch figure.
A modestly priced multimode transceiver kit doing CW, digital, and SSB. It does what the QDX does, plus CW with fast QSK and SSB, on an embedded SDR, in a shirt-pocket size. The QMX+ variant extends coverage to 160-6 m.
The QRP Labs QMX is the most ambitious of Hans Summers' little kits: a multimode HF transceiver barely larger than a pack of cards that does CW, all the popular digital modes, and - since 2025 - single-sideband voice, for around a hundred dollars. It is the multimode successor to the digital-only QDX: where the QDX is essentially a clever USB sound card with a transmitter attached, the QMX adds a display, a tuning encoder, a real CW keyer and decoder, and SSB.
Underneath is a genuine software-defined radio built on a 168 MHz ARM Cortex-M4, giving an embedded SDR receiver with 60-70 dB of sideband rejection, configurable CW filters, and fast, click-free QSK break-in. For digital work it is its own 24-bit USB sound card over a single USB-C cable, exactly like the QDX. It is sold in three band-group versions, each covering five or six bands between 80 and 10 meters, and a larger sibling - the QMX+ - covers all twelve bands from 160 through 6 meters and adds a real-time clock and an internal GPS option.
The SSB is the interesting story. Rather than a conventional voice modulator and linear amplifier, the QMX synthesizes SSB by polar modulation: it splits the speech into phase and amplitude, steers the oscillator's frequency for the phase part, and modulates the supply voltage to the switching amplifier for the amplitude, with an automatic routine that calibrates out the distortion. It is an unusual, elegant way to get clean voice from a tiny non-linear transmitter, and after a long beta it became an official, stable feature in May 2025. As with the QCX, the radio carries its own test and alignment tools.
One warning matters more than any other: the QMX runs from 6 to 12 volts only, and a standard 13.8-volt supply will damage it - this is the most common way owners kill one. Build it for 9 or 12 volts and feed it accordingly. It is a more advanced build than the CW-only QCX-mini, and assembled units carry a long wait, but nothing else at the price does CW, digital, and SSB in a shirt pocket. If you only want digital modes, the simpler QDX remains the cheaper choice.