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QRP Labs QMX Gets a Serious CW Upgrade: What Firmware 1.04.004 Changes

A small firmware update with some meaningful improvements for QRP and CW operators.

A firmware update may not sound exciting, but for CW operators using the QRP Labs QMX, version 1.04.004 brings several changes worth paying attention to.

The QRP Labs QMX has become an interesting little radio for operators who enjoy QRP, CW, digital modes, portable operating, and experimenting with software-defined radio technology.

One of the advantages of a modern software-defined transceiver is that the radio sitting on your desk today doesn’t necessarily have to be the same radio you bought months ago. Firmware can correct problems, refine operating characteristics, and even add capabilities without replacing any hardware.

That’s exactly what QRP Labs continues to do with the QMX.

Firmware version 1.04.004, released July 23, 2026, includes several changes that should be particularly interesting to CW operators.

Better Control Over CW Transmit Shaping

Perhaps the most interesting part of the update is additional control over the QMX’s CW shaping.

CW isn’t simply a matter of switching an RF carrier instantly on and off. The way the transmitter brings the signal up to full power and then reduces it again can affect how the transmitted CW sounds.

Transitions that are too abrupt can contribute to unwanted key clicks and unnecessarily widen the transmitted signal.

With firmware 1.04.004, QRP Labs provides additional control over the CW shaping envelope and rise and fall times.

For the everyday operator, the important point is simple:

You have more control over how your CW signal is generated.

That’s especially welcome on a radio likely to be used by operators who care about clean CW signals.

CW Key-Down Spike Addressed

Another important change involves a CW key-down spike.

A brief power spike at the beginning of a transmission may only last a very short time, but correcting that behavior helps make the transmitter’s output more predictable and controlled.

For a QRP transceiver, where operators are deliberately working with only a handful of watts, good control of the transmitted signal is particularly desirable.

The firmware addresses this issue as part of QRP Labs’ continuing refinement of the QMX.

Semi-QSK Improvements

The update also contains a correction related to Semi-QSK operation.

QSK, or break-in CW, allows a CW operator to transition rapidly between transmitting and receiving. It’s one of those features that may not mean much to someone primarily operating SSB, but experienced CW operators quickly notice when transmit/receive switching doesn’t feel right.

Good break-in behavior can make CW operation feel much more natural.

The Semi-QSK changes therefore aren’t simply another obscure item buried in a firmware changelog. For operators who spend a lot of time behind a paddle, improvements in this area can have a noticeable effect on the operating experience.

New CAT Commands

Firmware 1.04.004 also expands computer control of the QMX through additional CAT commands.

New commands include support associated with GPS information and SWR protection.

CAT—or Computer Aided Transceiver control—is increasingly important because modern amateur-radio stations often combine the radio with logging programs, digital-mode software, station automation, and other computer-controlled equipment.

The additional commands provide developers and experimenters with more ways to integrate the QMX into a computer-controlled station.

For operators who enjoy experimenting with software and station automation, this may ultimately prove to be one of the more interesting parts of the update.

Changes to SWR Protection

SWR protection is particularly important in a small QRP transceiver.

Portable operators regularly change antennas, feed lines, bands, and operating locations. Inevitably, sooner or later, someone presses the key when the antenna isn’t quite what they thought it was.

Having the radio monitor conditions and protect its output stage provides another layer of protection for the transmitter.

The new CAT capabilities associated with SWR protection could also provide interesting possibilities for external software and station monitoring.

A 12-Watt Meter Scale Option

There’s another interesting addition for experimenters.

Firmware 1.04.004 includes a 12-watt power-meter scale option intended for configurations where the QMX power amplifier has been modified.

Most QMX operators probably won’t need this setting.

But its inclusion says something interesting about QRP Labs and its customer base. This is equipment designed for a community where experimentation and modification are still very much encouraged.

That’s something I’ve always appreciated about the QRP side of amateur radio.

SMPS Bias Pre-Warming

The update also introduces SMPS bias pre-warming.

The QMX uses sophisticated power-management techniques inside a remarkably small package. Changes such as bias pre-warming are aimed at improving the way those internal systems behave as the radio transitions into operation.

It’s one of those behind-the-scenes refinements that may never receive the attention of a new menu item or flashy feature.

But these small engineering changes can contribute to making a mature radio more polished.

Why This Update Matters

None of these changes individually turns the QMX into a completely different transceiver.

• Cleaner CW behavior
• Better transmit control
• Improved Semi-QSK operation
• More flexible CW shaping
• Expanded CAT control
• Better protection and monitoring
• Support for experimentation and modified hardware

And that’s actually the point.

Good firmware development isn’t always about adding a spectacular new feature.

Sometimes it’s about improving the details:

Meta description: QRP Labs QMX firmware 1.04.004 adds CW shaping controls, Semi-QSK improvements, CAT commands, SWR features and other refinements for QRP operators.

Put those improvements together and you have a radio that’s continuing to mature after it has already reached operators’ shacks.

The QMX and the Modern QRP Radio

The QMX represents an interesting change in what we expect from inexpensive QRP equipment.

Years ago, buying a small QRP transceiver generally meant that its capabilities were essentially frozen the day it left the factory.

Modern SDR-based radios have changed that.

Today, manufacturers can continue refining receiver behavior, transmit characteristics, digital interfaces, CAT commands, keying behavior, and other features through firmware.

Your radio can literally operate differently after an update.

For experimenters, that’s exciting.

It also means amateur-radio operators should start treating firmware updates much like we treat adjustments and maintenance elsewhere in the station.

Should You Install Firmware 1.04.004?

If you’re operating a QMX—particularly if you’re an active CW operator—this is an update worth investigating.

The improvements to CW shaping, keying behavior, Semi-QSK operation, and CAT control are more than cosmetic changes.

As always, read the QRP Labs release notes and firmware installation instructions before updating your radio. Confirm that you’re installing the correct firmware for your hardware and preserve any settings or configuration information recommended by QRP Labs.

There’s rarely a prize for being the first person to install new firmware.

There is considerable value, however, in understanding what the update changes before pressing the button.

Final Thoughts

The QRP Labs QMX is a good example of where amateur-radio equipment is heading.

It’s small. It’s software driven. It’s affordable compared with many full-size transceivers, and it’s designed for the sort of operator who isn’t afraid to experiment.

Firmware 1.04.004 doesn’t reinvent the QMX.

Instead, it tackles exactly the kind of details serious CW and QRP operators tend to appreciate.

And for a little QRP radio, that’s probably more important than adding another flashy feature to the menu.

73,
KE2YK

Portable Antennas for Serious DXing: Don’s Field Tests from Parks to the Open Road (Part 1)

https://swling.com/blog/2025/12/portable-antennas-for-serious-dxing-dons-field-tests-from-parks-to-the-open-road-part-1/

#AirspyHFDiscovery #Antennas #DmgicProMLA30 #DonMoore #DrakeR8 #EladFDMS2 #FieldAntennas #LoopAntennas #MLA30MegaLoop #PA0RDTMiniwhip #RoelofBakkerPA0RDT #SonyICF2010 #WellbrookALA100LN

Landsat At Work – Better Wireless Communication - National Land Cover Database (NLCD), Based On Landsat, Helps Plan Clear Signal
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https://www.usgs.gov/centers/eros/news/landsat-work-a-path-better-wireless-communication <-- shared article
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https://www.usgs.gov/landsat-missions <-- shared about Landsat
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https://www.usgs.gov/centers/eros/science/annual-national-land-cover-database <-- shared about NLCD
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#GIS #spatial #mapping #Landsat #remotesensing #satellite #earthobservation #fedscience #usecase #USGS #EROS #cellphone #mobilephone #telecommunications #communications #cost #benefit #wireless #towers #antennas #landcover #landuse #NLCD #radio #frequency #siting #lineofsight #clutter #economics #risk #hazard #signal #signalquality #USA #value #returnoninvestment
@USGS @USGS_EROS