While ham radio operators have been embracing digital mobile radio (DMR), the equipment is most often bought since — at least in early incarnations — it needs a proprietary CODEC to convert speech to digital and vice versa. But [QRadioLink] decided to tackle a homebrew and open source DMR modem.

The setup uses a LimeSDR, GNU Radio, and Codec2. There are some other open DMR projects, such as OpenRTX. So we are hopeful there are going to be more choices. The DMR modem, however, is only a proof-of-concept and reuses the MMDVMHost code to do the data link layer.

[QRadioLink] found several receiver implementations available, but only one other DMR transmitter — actually, a transceiver. Rather than use an AMBE hardware device or the potentially encumbered mbelib codec, the project uses Codec2 which is entirely open source.

There’s a lot of explanation about the data collection to prepare for the project, and then a deep dive into the nuts and bolts of the implementation. You might enjoy the video below to see things in action.

If you just want to listen to DMR, it’s easy. If Codec2 sounds familiar, it is part of M17.

It’s been a while since we’ve dunked on an autonomous taxi foul-up, mainly because it seemed for a while there that most of the companies field testing driverless ride-sharing services had either ceased operation or curtailed them significantly. But that appears not to be the case after a Waymo robotaxi got stuck in a Chick-fil-A drive-through. The incident occurred at the chicken giant’s Santa Monica, California location at about 9:30 at night, when the autonomous Jaguar got stuck after dropping off a passenger in the parking lot. The car apparently tried to use the drive-through lane to execute a multi-point turn but ended up across the entrance, blocking other vehicles seeking their late-evening chicken fix. The drive-through-only restaurant ended up closing for a short time while Waymo figured out how to get the vehicle moving again.

To be fair, drive-through lanes are challenging even for experienced drivers. Lanes are often narrow, curve radii are sometimes tighter than a large vehicle can negotiate smoothly, and the task-switching involved with transitioning from driver to customer can lead to mistakes. Drive-throughs almost seem engineered to make tempers flare, especially at restaurants where hangry drivers are likely to act out at the slightest delay. This is probably doubly so when drivers are stuck behind a driverless car, completely eliminating even the minimal decency that would likely be extended to a human driver who got themselves in a pickle. If people are willing to honk at and curse out the proverbial little old lady from Pasadena, they’re very unlikely to cooperate with a robotaxi and give it the room it needs to maneuver out of a tight spot. Perhaps that argues for a change in programming that accounts for real-world driving experiences as well as the letter of the law.

The big news from space this week was the private Fram2 mission, which took an all-civilian crew on the world’s first crewed polar flight. The four-person crew took off from Florida in a SpaceX Crew Dragon and rather than heading east towards Africa, took off due north and entered a retrograde orbit at 90° inclination, beating the previous record of 65° inclination by Valentina Tereshkova aboard Vostok 6 back in 1963. The Fram2 team managed a couple of other firsts, from the first medical X-rays taken in space to the first amateur radio contacts made from the Dragon.

It’s been a while, but Bill “The Engineer Guy” Hammack is back with a new video extolling the wonders of plastic soda bottles. If you think that’s a subject too mundane to hold your interest, then you’ve never seen Bill at work. The amount of engineering that goes into creating a container that can stand up to its pressurized content while being able to be handled both by automation machines at the bottling plant and by thirsty consumers is a lesson in design brilliance. Bill explains the whole blow-molding process, amazingly using what looks like an actual Coca-Cola production mold. We would have thought such IP would be fiercely protected, but such is Bill’s clout, we guess. The video is also a little trip down memory lane for some of us, as Bill shows off both the two-piece 2-liter bottles that used to grace store shelves and the ponderous glass versions that predated those. Also interesting is the look at the differences between hot-fill bottles and soda bottles, which we never appreciated before.

And finally, if you’ve ever been confused by which logical fallacy is clouding your thinking, why not turn to the most famous fictional logician of all time to clarify things? “Star Trek Logical Reasoning” is a YouTube series by CHDanhauser that uses clips from the Star Trek animated series to illustrate nearly 70 logical fallacies. Each video is quite short, with most featuring Commander Spock eavesdropping on the conversations of his less-logical shipmates and pointing out the flaws in their logic. Luckily, the 23rd century seems to have no equivalent of human(oid) resources, because Spock’s logical interventions are somewhat toxic by today’s standards, but that’s a small price to pay for getting your logical ducks in a row.

Would-be spooks and spies, take note: this one-transistor FM transmitter is a circuit you might want to keep in mind for your bugging needs. True, field agents aren’t likely to need to build their own equipment, but how cool a spy would you be if you could?

Luckily, you won’t need too many parts to recreate [Ciprian (YO6DXE)]’s project, most of which could be found in a decently stocked junk bin, or even harvested from e-waste. On the downside, the circuit is pretty fussy, with even minor component value changes causing a major change in center frequency. [Ciprian] had to do a lot of fiddling to get the frequency in the FM band, particularly with the inductor in the LC tank circuit. Even dropping battery voltage shifted the frequency significantly, which required a zener diode to address.

[Ciprian] ran a few tests and managed to get solid copy out to 80 meters range, which is pretty impressive for such a limited circuit. The harmonics, which extend up into the ham bands and possibly beyond, are a bit of a problem; while those could be addressed with a low-pass filter, in practical terms, the power of this little fellow is probably low enough to keep you from getting into serious trouble. Still, it’s best not to push your luck.

While you’re trying your hand at one-transistor circuits, you might want to try [Ciprian]’s one-transistor CW transceiver next.

[Jamie] decided to build a generator, and Lego is his medium of choice. Thus was created a fancy levitating generator that turns a stream of air into electricity. 

The basic concept is simple enough for a generator—magnets moving past coils to generate electricity. Of course, Lego doesn’t offer high-strength magnetic components or copper coils, so this generator is a hybrid build which includes a lot of [Jamie’s] non-Lego parts. Ultimately though, this is fun because of the weird way it’s built. Lego Technic parts make a very crude turbine, but it does the job. The levitation is a particularly nice touch—the build uses magnets to hover the rotor in mid-air to minimize friction to the point where it can free wheel for minutes once run up to speed. The source of power for this contraption is interesting, too. [Jamie] didn’t just go with an air compressor or a simple homebrew soda bottle tank. Instead, he decided to use a couple of gas duster cans to do the job. The demos are pretty fun, with [Jamie] using lots of LEDs and a radio to demonstrate the output.  The one thing we’d like to see more of is proper current/voltage instrumentation—and some measurement of the RPM of this thing!

While few of us will be rushing out to build Lego generators, the video nonetheless has educational value from a mechanical engineering standpoint. Fluids and gases really do make wonderful bearings, as we’ve discussed before. Video after the break.

When the AMSAT-OSCAR 7 (AO-7) amateur radio satellite was launched in 1974, its expected lifespan was about five years. The plucky little satellite made it to 1981 when a battery failure caused it to be written off as dead. Then, in 2002 it came back to life. The prevailing theory being that one of the cells in the satellites NiCd battery pack, in an extremely rare event, failed open — thus allowing the satellite to run (intermittently) off its solar panels.

In a recent video by [Ben] on the AE4JC Amateur Radio YouTube channel goes over the construction of AO-7, its operation, death and subsequent revival are covered, as well as a recent QSO (direct contact).

The solar panels covering this satellite provided a grand total of 14 watts at maximum illumination, which later dropped to 10 watts, making for a pretty small power budget. The entire satellite was assembled in a ‘clean room’ consisting of a sectioned off part of a basement, with components produced by enthusiasts associated with AMSAT around the world. Onboard are two radio transponders: Mode A at 2 meters and Mode B at 10 meters, as well as four beacons, three of which are active due to an international treaty affecting the 13 cm beacon.

Positioned in a geocentric LEO (1,447 – 1,465 km) orbit, it’s quite amazing that after 50 years it’s still mostly operational. Most of this is due to how the satellite smartly uses the Earth’s magnetic field for alignment with magnets as well as the impact of photons to maintain its spin. This passive control combined with the relatively high altitude should allow AO-7 to function pretty much indefinitely while the PV panels keep producing enough power. All because a NiCd battery failed in a very unusual way.

We know how [Techmoan] feels. In the 1980s we had a bewildering array of oddball gadgets and exciting new tech. But as kids we didn’t have money to buy a lot of what we saw. But he had a £5 note burning a hole in his pocket from Christmas and found a Casio RD-10 “card radio” on sale and grabbed it. He’s long-ago lost that one, but he was able to find a new old stock one and shows us the little gadget in the video below.

The card-thin (1.9 mm) FM radio had many odd features, especially for the 1980s. For one thing, it took a coin cell, which was exotic in those days. The headphones had a special flat connector that reminded us of an automotive fuse. Even the idea of an earbud was odd at that time.

It was a good idea not to lose the earbud, as it had that strange connector. The earbud worked as the antenna and power switch, too. Oddly enough, you could get a slightly fatter AM radio version, and they even made one that was AM and FM. Unsurprisingly, Casio even made a version with a calculator built-in. It had a solar cell, but that only powers the calculator. You still needed the coin cell for the radio.

The sound? Meh. But what did you expect? There was a stereo version, too. However, that one had a rechargeable battery, which was not in good health after a few decades. He also shows a Sony card radio that is a bit different. We were hoping for a teardown, especially of the rechargeable since it was toast, anyway, but for now, we’ll have to imagine what’s inside.

We love nostalgic radios, although usually they are a little older. We miss the days when a kid might think it was cool to see an ad touting: “Oh boy! We’re radio engineers!”

GPS is an incredible piece of modern technology. Not only does it allow for locating objects precisely anywhere on the planet, but it also enables the turn-by-turn directions we take for granted these days — all without needing anything more than a radio receiver and some software to decode the signals constantly being sent down from space. [Chris] took that last bit bit as somewhat of a challenge and set off to write a software-defined GPS receiver from the ground up.

As GPS started as a military technology, the level of precision needed for things like turn-by-turn navigation wasn’t always available to civilians. The “coarse” positioning is only capable of accuracy within a few hundred meters so this legacy capability is the first thing that [Chris] tackles here. It is pretty fast, though, with the system able to resolve a location in 24 seconds from cold start and then displaying its information in a browser window. Everything in this build is done in Python as well, meaning that it’s a great starting point for investigating how GPS works and for building other projects from there.

The other thing that makes this project accessible is that the only other hardware needed besides a computer that runs Python is an RTL-SDR dongle. These inexpensive TV dongles ushered in a software-defined radio revolution about a decade ago when it was found that they could receive a wide array of radio signals beyond just TV.

There’s something magical about the clunk of a heavy 1950s portable radio – the solid thunk of Bakelite, the warm hum of tubes glowing to life. This is exactly why [Ken’s Lab] took on the restoration of a Philco 52-664, a portable AC/DC radio originally sold for $45 in 1953 (a small fortune back then!). Despite its beat-up exterior and faulty guts, [Ken] methodically restored it to working condition. His video details every crackling capacitor and crusty resistor he replaced, and it’s pure catnip for any hacker with a soft spot for analog tech. Does the name Philco ring a bell? Lately, we did cover the restoration of a 1958 Philco Predicta television.

What sets this radio hack apart? To begin with, [Ken] kept the restoration authentic, repurposing original capacitor cans and using era-appropriate materials – right down to boiling out old electrolytics in his wife’s discarded cooking pot. But, he went further. Lacking the space for modern components, [Ken] fabbed up a custom mounting solution from stiff styrofoam, fibreboard, and all-purpose glue. He even re-routed the B-wiring with creative terminal hacks. It’s a masterclass in patience, precision, and resourcefulness.

If this tickles your inner tinkerer, don’t miss out on the full video. It’s like stepping into a time machine.

[Tech Minds] built one of those cheap automatic antenna tuners you see everywhere — this one scaled up to 350 watt capability. The kit is mostly built, but you do have to add the connectors and a few other stray bits. You can see how he did it in the video below.

What was very interesting, however, was that it wasn’t able to do a very good job tuning a wire antenna across the ham bands, and he asks for your help on what he should try to make things better.

It did seem to work in some cases, and changing the length of the wire changed the results, so we would guess some of it might be a resonance on the antenna wire. However, you would guess it could do a little better. It is well known that if a wire is one of a number of certain lengths, it will have extremely high impedence in multiple ham bands and be challenging to tune. So random wires need to not be exactly random. You have to avoid those lengths.

In addition, we were surprised there wasn’t more RF protection on the power lines. We would probably have suggested winding some coax to act as a shield choke, RF beads, and even extra bypass capacitors.

Another possible problem is that the diodes in these units are often not the best. [PU1OWL] talks about that in another video and bypasses some of the power lines against RF, too.

If you have any advice, we are sure he’d love to hear it. As [PU1OWL] points out, a tuner like this can’t be any better than its SWR measurement mechanism. Of course, all of these tuners take a few watts to light them up. You can, however, tune with virtually no power with a VNA.

We used to say that fixing something was easier than bringing up a design for the first time. After all, the thing you are fixing, presumably, worked at one time or another. These days, that’s not always true as fixing modern gear can be quite a challenge. Watching [Ken’s] repair of an old 1955 Silvertone radio reminded us of a simpler time. You can watch the action on the video below.

If you’ve never had the pleasure of working on an AM radio, you should definitely try it. Some people would use an amplifier to find where the signal dies out. Others will inject a signal into the radio to find where it stops. A good strategy is to start at the volume control and decide if it is before or after that. Then split the apparently bad section roughly in half and test that portion—sort of a hardware binary search. Of course, your first step should probably be to verify power, but after that, the hunt is on.

There’s something very satisfying about taking a dead radio and then hearing it come to life on your bench. In this case, some of the problems were from a previous repair.

Troubleshooting is an art all by itself. Restoring old radios is also great fun.

Shortwave radio has a charm all its own: part history, part mystery, and a whole lot of tech nostalgia. The Hallicrafters S-53A is a prime example of mid-century engineering, but when you get your hands on one, chances are it won’t be in mint condition. Which was exactly the case for this restoration project by [Ken’s Lab], where the biggest challenge wasn’t fried capacitors or burned-out tubes, but a stubborn band selector switch that refused to budge.

What made it come to this point? The answer is: time, oxidation, and old-school metal tolerances. Instead of forcing it (and risking a very bad day), [Ken]’s repair involved careful disassembly, a strategic application of lubricant, and a bit of patience. As the switch started to free up, another pleasant surprise emerged: all the tubes were original Hallicrafters stock. A rare find, and a solid reason to get this radio working without unnecessary modifications. Because some day, owning a shortwave radio could be a good decision.

Once powered up, the receiver sprang to life, picking up shortwave stations loud and clear. Hallicrafters’ legendary durability proved itself once before, in this fix that we covered last year. It’s a reminder that sometimes, the best repairs aren’t about drastic changes, but small, well-placed fixes.

What golden oldie did you manage to fix up?

Making a multi-band amateur radio transceiver has always been a somewhat challenging project, and making one that also supported different modes would for many years have been of almost impossible complexity best reserved for expensive commercial projects. [Bob W7PUA] has tackled both in the form of a portable 10-band multi-mode unit, and we can honestly say he’s done a very good job indeed.

As you might expect in 2025 it’s a software defined radio (SDR), but to show how powerful the silicon available today is, it’s all implemented on a microcontroller. There’s a Teensy 4 with an audio codec board that does all the signal processing heavy lifting, and an RF board that takes care of the I/Q mixing and the analogue stuff.

Band switching is handled using a technique from the past; interchangeable plug-in coil and filter units, that do an effective job. The result is a modestly-powered but extremely portable rig that doesn’t look to have broken the bank, and since the write-up goes into detail on the software side we hope it might inform other SDR projects too. We might have gone for old-school embossed Dymo labels on that brushed aluminium case just for retro appeal, but we can’t fault it.

It’s not the first time we’ve looked at a small multi-band SDR here, but we think this one ups the game somewhat.

Thanks [Pete] for the tip!

We hear a lot about how ham radio isn’t what it used to be. But what was it like? Well, the ARRL’s film “The Ham’s Wide World” shows a snapshot of the radio hobby in the 1960s, which you can watch below. The narrator is no other than the famous ham [Arthur Godfrey] and also features fellow ham and U.S. Senator [Barry Goldwater]. But the real stars of the show are all the vintage gear: Heathkit, Swan, and a very oddly placed Drake.

The story starts with a QSO between a Mexican grocer and a U.S. teenager. But it quickly turns to a Field Day event. Since the film is from the ARRL, the terminology and explanations make sense. You’ll hear real Morse code and accurate ham lingo.

Is ham radio really different today? Truthfully, not so much. Hams still talk to people worldwide and set up mobile and portable stations. Sure, hams use different modes in addition to voice. There are many options that weren’t available to the hams of the 1960s, but many people still work with old gear and older modes and enjoy newer things like microwave communications, satellite work, and even merging radio with the Internet.

In a case of history repeating itself, there is an example of hams providing communications during a California wildfire. Hams still provide emergency communication in quite a few situations. It is hard to remember that before the advent of cell phones, a significant thing hams like [Barry Goldwater] did was to connect servicemen and scientists overseas to their families via a “phone patch.” Not much of that is happening today, of course, but you can still listen in to ham radio contacts that are partially over the Internet right in your web browser.

Just when you thought the saga of the Bitcoin wallet lost in a Welsh landfill was over, another chapter of the story appears to be starting. Regular readers will recall the years-long efforts of Bitcoin early adopter James Howells to recover a hard drive tossed out by his ex back in 2013. The disk, which contains a wallet holding about 8,000 Bitcoin, is presumed to be in a landfill overseen by the city council of Newport, which denied every request by Howells to gain access to the dump. The matter looked well and truly settled (last item) once a High Court judge weighed in. But the announcement that the Newport Council plans to cap and close the landfill this fiscal year and turn part of it into a solar farm has rekindled his efforts.

Howells and his investment partners have expressed interest in buying the property as-is, in the hopes of recovering the $780 million-ish fortune. We don’t think much of their odds, especially given the consistently negative responses he’s gotten over the last twelve years. Howells apparently doesn’t fancy his odds much either, since the Council’s argument that closing the landfill to allow him to search would cause harm to the people of Newport was seemingly made while they were actively planning the closure. It sure seems like something foul is afoot, aside from the trove of dirty diapers Howells seeks to acquire, of course.

When all else fails, blame the monkey. The entire nation of Sri Lanka suffered a blackout last Sunday, with a hapless monkey being fingered as the guilty party. The outage began when a transformer at a substation south of the capital city of Colombo went offline. Unconfirmed reports are that a troop of monkeys was fighting, as monkeys do, and unadvisedly brought their tussle over the fence and into the substation yard. At some point, one of the warring animals sought the high ground on top of a transformer, with predictable results. How turning one monkey into air pollution managed to bring down an entire country’s grid is another question entirely.

From the enshittification files comes this horrifying story of in-dashboard ads. Stellantis, maker of Jeep, Dodge, Chrysler, and other brands that can reliably be counted upon to be littered with bad grounds, has decided to start putting full-screen pop-up advertisements on infotainment systems. As if that’s not atrocious enough, the ads will run not just when the car is first started, but every time the vehicle comes to a stop in traffic. The ads will hawk things like extended warranties, at least initially, but we predict it won’t be long before other upsell attempts are made. It would be pretty easy to pull in other data to customize ads, such as an offer to unlock heated seats if the outside temperature gets a little chilly, or even flog a pumpkin spice latte when the GPS shows you’re near a Starbucks. The possibilities are endless, and endlessly revolting, because if one car company does it, the rest will quickly follow. Ad-blocking wizards, this may be your next big target.

And finally, calling all hams, or at least those of us with an interest in digital modes. Our own Al Williams will be making an appearance on the DMR Tech Net to talk about his Hackaday recent article on Digital Mobile Radio. The discussion will be on Monday, February 17 at 00:30 UTC (19:30 EST), on Brandmeister talk group 31266. If you’ve got a DMR-capable radio, DMR Tech Net has a handy guide to getting the talk group into your code plug. If none of that makes any sense, relax — you can still tune in online using this link and the Player button in the upper right. Or, if ham radio isn’t your thing, Al will be making a second appearance the next night but on a Zoom call to discuss “How to Become Rich and (almost) Famous on Hackaday,” which is his collection of tips and tricks for getting your project to catch a Hackaday writer’s eye.