[ZXGuesser] has pulled off a true feat of Meccano engineering: building a Meccano Hellschreiber machine. The design is a close replica of the original Siemens Feld-Hell machine as documented here. What is Hellschreiber, you might ask? It’s a very neat method of sending written messages over the air by synchronizing a printing wheel on the receiving end with pulses generated on the transmitter. By quickly moving the print wheel up and down, arbitrary figures can be printed out. If you want to learn more about Hellschreiber, check out this excellent Hackaday post from almost a decade ago!

The Mastodon thread linked above goes into more detail about the difficulty in building this behemoth — and the slight regret of sticking with the authentic QWERTZ keyboard layout! In order to use the Hellschreiber mode, you have to keep up a steady rhythm of typing at about 2.5 characters per second, otherwise, the receiving end will see randomly spaced gaps between each letter. So while having to type at a steady speed [ZXGuesser] also had to work with a slightly different keyboard layout. Despite this difficulty, some very good quality output was generated!

Incredibly, the output looks just like the output from the original, century-old design. We think this is an absolutely incredible accomplishment, and we hope [ZXGuesser] doesn’t follow through on disassembling this amazing replica — or if they do, we hope it’s documented well enough for others to try their hand at it!

Thanks [BB] for the tip!

In the days before integrated circuits became ubiquitous, providing advanced functionality in a single package, designers became adept at extracting the maximum use from discrete components. They’d use clever circuits in which a transistor or other active part would fulfill multiple roles at once, and often such circuits would need more than a little know-how to get working. It’s not often in 2024 that we encounter this style of circuit, but here’s [Maurycy] with a cheap microwave radar module doing just that.

On the board is an RF portion with a single transistor, some striplines, and an SOIC chip. Oddly this last part turns out to be an infra-red proximity sensor chip, so what’s going on? Careful analysis of the RF circuit reveals something clever. As expected, it’s a 3.18 GHz oscillator, but how is it functioning as both transmitter and receiver? The answer comes in the form of a resistor and capacitor in the emitter circuit, which causes the transistor to also oscillate at about 20 kHz. The result is that at different times in the 20 kHz period, the transistor is either off, fully oscillating at 3.18GHz and transmitting, or briefly in the not-quite-oscillating state between the two during which it functions as a super-regenerative receiver. This is enough for one device to effectively transmit and receive at the same time with the minimum of parts, there’s no need for a mixer diode as you might expect if it were it a direct conversion receiver. Perhaps in RF terms, it’s not particularly pretty, but we have to admit to being impressed by its simplicity. He goes on to perform a few experiments with the board as a transmitter or as a more conventional radar.

This isn’t the first such radar module we’ve looked at, here’s one designed from scratch. And we love regens, since they are so simple to build.

Meshtastic is a way to build mesh networks using LoRa that is independent of cell towers, hot spots or traditional repeaters. It stands to reason that with an SDR and GNU Radio, you could send and receive Meshtastic messages. That’s exactly what [Josh Conway] built, and you can see a video about the project, Meshtastic_SDR, below. The video is from [cemaxecuter], who puts the library through its paces.

For hardware, the video uses a Canary I as well as the WarDragon software-defined radio kit which is an Airspy R2 and a mini PC running Dragon OS — a Linux distribution aimed at SDR work —  in a rugged case. GNU Radio, of course, uses flows which are really just Python modules strung together with a GUI.

The GNU blocks send and receive data via TCP port, so using the radio as a data connection is simple enough. The flow graph itself for the receiver looks daunting, but we have a feeling you won’t change the default very much.

If you’ve wanted to dip your toe into Meshtastic or you want a meaty example of using GNU Radio, this would be a fun project to duplicate and extend. While Meshtastic is generally a mesh protocol, you can set up a node to act as a repeater. You never know when decentralized communications might save the day.

Morse code, often referred to as continuous wave (CW) in radio circles, has been gradually falling out of use for a long time now. At least in the United States, ham radio licensees don’t have to learn it anymore, and the US Coast Guard stopped using it even for emergencies in 1999. It does have few niche use cases, though, as it requires an extremely narrow bandwidth and a low amount of power to get a signal out and a human operator can usually distinguish it even if the signal is very close to the noise floor. So if you want to try and learn it, you might want to try something like this Morse trainer from [mircemk].

While learning CW can be quite tedious, as [mircemk] puts it, it’s actually fairly easy for a computer to understand and translate so not a lot of specialized equipment is needed. This build is based around the Arduino Nano which is more than up for the job. It can accept input from any audio source, allowing it to translate radio transmissions in real time, and can also be connected to a paddle or key to be used as a trainer for learning the code. It’s also able to count the words-per-minute rate of whatever it hears and display it on a small LCD at the front of the unit which also handles displaying the translations of the Morse code.

If you need a trainer that’s more compact for on-the-go CW, though, take a look at this wearable Morse code device based on the M5StickC Plus instead.

OK, it’s official: the Quansheng UV-K5 is the king of hackable ham radios — especially now that a second version of the all-band hardware and firmware mod has been released, not to mention a new version of the radio.

If you need to get up to speed, check out our previous coverage of the all-band hack for the UV-K5, in which [Paul (OM0ET)] installs a tiny PCB to upgrade the radio’s receiver chip to an Si4732. Along with a few jumpers and some component replacements on the main board, these hardware mods made it possible for the transceiver, normally restricted to the VHF and UHF amateur radio bands, to receive everything down to the 20-meter band, in both AM and single-sideband modulations.

The new mod featured in the video below does all that and more, all while making the installation process slightly easier. The new PCB is on a flexible substrate and is considerably slimmer, and also sports an audio amplifier chip, to make up for the low audio output on SSB signals of the first version. Installation, which occupies the first third of the video below, is as simple as removing one SMD chip from the radio’s main board and tacking the PCB down in its footprint, followed by making a couple of connections with very fine enameled wire.

You could load the new firmware and call it a day at that point, but [Paul] decided to take things a step further and install a separate jack for a dedicated HF antenna. This means sacrificing the white LED on the top panel, which isn’t much of a sacrifice for most hams, to make room for the jack. Most of us would put a small SMA jack in, but [Paul] went for a BNC, which required some deft Dremel and knife work to fit in. He also used plain hookup wire to connect the jack, which sounds like a terrible idea; we’d probably use RG-316, but his mod didn’t sound that bad at all.

Keen to know more about the Quansheng UV-K5? Dive into the reverse-engineered schematics.

Thanks to [Sam] for the heads up on this one.

We’ve said it before and we’ll say it again: being able to build your own radios is the best thing about being an amateur radio operator. Especially low-power transmitters; there’s just something about having the know-how to put something on the air that’ll reach across the planet on a power budget measured in milliwatts.

This standalone WSPR beacon is a perfect example. If you haven’t been following along, WSPR stands for “weak-signal propagation reporter,” and it’s a digital mode geared for exploring propagation that uses special DSP algorithms to decode signals that are far, far down into the weeds; signal-to-noise ratios of -28 dBm are possible with WSPR.

Because of the digital nature of WSPR encoding and the low-power nature of the mode, [IgrikXD] chose to build a standalone WSPR beacon around an ATMega328. The indispensable Si5351 programmable clock generator forms the RF oscillator, the output of which is amplified by a single JFET transistor. Because timing is everything in the WSPR protocol, the beacon also sports a GPS receiver, ensuring that signals are sent only and exactly on the even-numbered minutes. This is a nice touch and one that our similar but simpler WSPR beacon lacked.

This beacon had us beat on performance, too. [IgrikXD] managed to hit Texas and Colorado from the edge of the North Sea on several bands, which isn’t too shabby at all with a fraction of a watt.

Thanks to [STR-Alorman] for the tip.

[via r/amateurradio]

We’ve been harping a lot lately about the effort by carmakers to kill off AM radio, ostensibly because making EVs that don’t emit enough electromagnetic interference to swamp broadcast signals is a practical impossibility. In the US, push-back from lawmakers — no doubt spurred by radio industry lobbyists — has put the brakes on the move a bit, on the understandable grounds that an entire emergency communication system largely centered around AM radio has been in place for the last seven decades or so. Not so in Japan, though, as thirteen of the nation’s 47 broadcasters have voluntarily shut down their AM transmitters in what’s billed as an “impact study” by the Ministry of Internal Affairs and Communications. The request for the study actually came from the broadcasters, with one being quoted in a hearing on the matter as “hop[ing] that AM broadcasting will be promptly discontinued.” So the writing is apparently on the wall for AM radio in Japan.

There was another close call this week with our increasingly active sun, which tried but didn’t quite launch a massive stream of plasma out into space. The M-class flare was captured in the act by the Solar Dynamics Observatory, which keeps an eye on what’s going on with our star. The video of the outburst is fascinating; it almost looks like a CGI render, but it’s real imaging and pretty spectacular. The active region on the sun’s surface suddenly belches out a few gigatons of plasma, which quickly get sucked right back down to the surface. You can actually see the material following ethereal lines of magnetic force, and the way it splashes when it hits the surface is just beautiful. Seeing this puts us in the mood for a feature on the SDO and how it gets these fascinating images, so stay tuned for that.

Also in space news, we’re saddened by the sudden loss of yet another of the Apollo astronauts. Bill Anders, lunar module pilot on Apollo 8, died Friday in a small plane crash off San Juan Island in Washington. Anders, 90, was piloting the Beechcraft T-34 Mentor, a single-engine military trainer aircraft from the 1950s. Anders’ only trip in space was Apollo 8, but what a trip it was. Along with Commander Frank Borman and pilot James Lovell, they were the first humans to leave Earth’s gravity well and visit another world, riding the mighty Saturn V rocket all the way to the Moon for a ten-orbit visit that paved the way for the landing on Apollo 11. He is also officially the luckiest photographer in history, having been in just the right place at just the right time to snap the famous “Earthrise” picture that gave us for the first time a Moon’s-eye-view of our fragile little world:

Godspeed, Major General Anders.

In more mundane news, a story from Maryland that should give anyone who depends on tools for a living a moment’s pause. Police cracked a massive tool-theft ring thanks to the actions of a carpenter who, sick of having his tools ripped off repeatedly, stashed a couple of AirTags among his stock in trade. When the inevitable occurred and his tools took a walk yet again, he tracked them to a storage facility and alerted police. They in turn conducted an investigation and got search warrants for twelve locations, where the scale of this criminal enterprise became apparent. Check out the photos in the story; mountains of cordless tools sorted by brand, DeWalt yellow here and Milwaukee red there. There’s a surprising amount of puke-green Ryobi, too; are people really trying to make money with those tools? Between the piles of cordless tools and the rows of air compressors, the total value of the haul is estimated to be from $3 to $5 million. Hats off to the carpenter for running his own mini-sting operation.

And finally, from the Genuinely Interesting Apps files we have ShadeMap, which does exactly what you think it does: plot shade and shadow on a map. It has controls for time and date, and zooms down to a pretty fine level of detail, even for the free version. Shadows from buildings, terrain, and trees are calculated and displayed, making it perfect for surveys of locations for solar power installations. There’s also supposed to be a way to virtually remove shadow-casting features, although we couldn’t find it; perhaps in a paid version? That would be a handy tool indeed to see which trees need to be cut down or which buildings demolished to improve your solar aspect. YMMV on that last one, of course.

Are you tired of the same old music, but can’t afford any new tunes, even if they’re on dead formats? Boy, do we know that feeling. Here’s what you do: build yourself a GlobeTune music player, and you’ll never want for new music again.

The idea is simple, really. Just turn what we assume is a nice, clicky knob, and after a bit of static (which is a great touch!), you get a new, random radio station from somewhere around the globe. [Alexis D.] originally built this as a way to listen to and discover new music while disconnecting from the digital world, and we think it’s a great idea.

[Alexis D.] has production in mind, so after a Raspberry Pi Zero W prototype, they set about redesigning it around the ESP32. The current status seems to be hardware complete, software forthcoming. [Alexis D.] says that a crowdfunding campaign is in the works, but that the project will be open-sourced once in an acceptable state. So stay tuned!

Speaking of dead-ish formats, here’s an Internet radio in a cassette form factor.

We’ve all been there. You left your Walkman at home and only have your trusty Game Boy. You want to take a break and just listen to some tunes. What to do? [orangeglo] has the answer now with the Orange FM cartridge.

This prototype cart features an onboard antenna or can also use the 3.5 mm headphone/antenna port on the cartridge to boost reception with either a dedicated antenna or a set of headphones. Frequencies supported are 64 – 108 Mhz, and spacing can be set for 100 or 200 kHz to accomodate most FM broadcasts setups around the world.

Older Game Boys can support audio through the device itself, but Advances will need to use the audio port on the cartridge. The Super Game Boy can pipe audio to your TV though, which seems like a delightfully Rube Goldberg-ian way to listen to the radio. Did we mention it also supports RDS, so you’ll know what that catchy tune is? Try that FM Walkman!

Can’t decide between this and your other carts? Try this revolving multi-cart solution. Have a Game Boy that needs some restoration? If it’s due to electrolyte damage, maybe start here?

Stay in the amateur radio hobby long enough and you might end up with quite a collection of antennas. With privileges that almost extend from DC to daylight, one antenna will rarely do everything, and pretty soon your roof starts to get hard to see through the forest of antennas. It may be hell on curb appeal, but what’s a ham to do?

One answer could be making one antenna do the work of two, as [Guido] did with this diplexer for dual APRS setups. Automatic Packet Reporting System is a packet radio system used by hams to transmit telemetry and other low-bandwidth digital data. It’s most closely associated with the 2-meter ham band, but [Guido] has both 2-meter (144.8-MHz) and 70-cm LoRa (433.775-MHz) APRS IGates, or Internet gateway receivers. His goal was to use a single broadband discone antenna for both APRS receivers, and this would require sorting the proper signals from the antenna to the proper receiver with a diplexer.

Note that [Guido] refers to his design as a “duplexer,” which is a device to isolate and protect a receiver from a transmitter when they share the same antenna — very similar to a diplexer but different. His diplexer is basically a pair of filters in parallel — a high-pass filter tuned to just below the 70-cm band, and a low-pass filter tuned just above the top of the 2-m band. The filters were designed using a handy online tool and simulated in LTSpice, and then constructed in classic “ugly” style. The diplexer is all-passive and uses air-core inductors, all hand-wound and tweaked by adjusting the spacing of the turns.

[Guido]’s diplexer performs quite well — only a fraction of a dB of insertion loss, but 45 to 50 dB attenuation of unwanted frequencies — pretty impressive for a box full of caps and coils. We love these quick and dirty tactical builds, and it’s always a treat to see RF wizardry in action.

In the 1960s, if you were a teenager in the United States, a big part of your life was probably music. There was a seemingly endless supply of both radio stations and 45s to keep you entertained. In the UK and other countries, though, the government held a monopoly on broadcasting, and they were not always enthralled with the music kids liked. Where there is demand, there is an opportunity, and several enterprising broadcasters set up radio stations at sea, the so-called pirate radio stations. In 1964, Irish businessman [Ronan O’Rahilly] did just this and founded Radio Caroline. Can you imagine that 60 years later, Radio Caroline is still around?

Not that it has been in operation for 60 years in a row. There were a few years the station’s ship had been impounded by creditors. Then, the ship ran aground on the Goodwin Sands and was damaged. You can see a news short from 1965 in the video below (Radio Caroline shows up at about the 1:50 mark).

True, Radio Caroline isn’t quite the same as it was. They operate mostly from a legal onshore studio now. But one weekend a month, a crew operates from the ship now in British waters.

Back in 1964, you might have had problems picking up Radio Caroline from far away. Now, the pirate station is as close as your web browser. The other big pirate station was RNI, and they are still around, too.

[Alex R2AUK] has been busy creating version two of a homebrew all-band ham radio transceiver. The unit has a number of features you don’t always see in homebrew radios. It covers the 80, 40, 30, 20, 17, 15, 12, and 10 meter bands. The receiver is a single-IF design with AGC. The transmitter provides up to 10W for CW and 5W for single sideband operations. There’s a built-in keyer, too. A lot of the documentation is in Russian (including the video below, which is part of a playlist). But translation tools are everywhere, so if you don’t speak Russian, you can still probably figure it out.

The VFO for both transmit and receive is an Si5351. The transmit chain is straightforward. The receiver reuses many of the same filters.

Like many projects these days, an attractive 3D-printed case gives the radio a polished look. If you prefer using a straight key to a keyer, the transmitter will use either. The microphone amplifier has built-in compression for good audio levels.

If you don’t want to roll your own, you can get similar ham gear that is ready-built. If you want to go minimal. we’ve seen a less-capable transceiver built with only seven transistors.

A perk of writing for Hackaday comes in the vast breadth of experience represented by our fellow writers. Through our colleague [Voja Antonić] for example we’ve gained an unparalleled insight into the cutting edge of 8-bit computing in 1980s Yugoslavia, of his Galaksija home computer, and of software being broadcast over [Zoran Modli]’s Ventilator 202 radio show.

We’re strongly reminded of this by hearing of the Slovenian Radio Študent broadcasting the classic Slovenian ZX Spectrum text adventure game Kontrabant 2, at the behest of the  Slovenian Computer History Museum. It’s been four decades and a lot of turbulent history, but once again 8-bit code will be heard on FM in Europe.

Some of our younger readers may never have experienced the joy of loading software from cassette, but in those days it represented a slow alternative to the eye-wateringly expensive floppy drives of the day. The software was represented as a serial bitstream translated into tones and recorded on a standard cassette recorder which was standard consumer electronics back then, and when played back through a speaker it was an ear-splitting sound with something in common with that of a modem handshake from a decade or more later. This could easily be transmitted over a radio station, and a few broadcasters tried experimental technology shows doing just that.

We haven’t heard from any listeners who managed to catch the game and run it on their Spectrum, but we hope that Slovenia’s retrocomputing community were out in force even if Audacity and a n emulator replaced the original hardware. Given that more than one hacker camp in our community has sported radio stations whether legal or not, it would be nice to hear the dulcet tones of 8-bit software on the airwaves again.

Meanwhile if cassettes are too cheap for you, feast your eyes on Sir Clive’s budget storage solution.

Thanks [Stephen Walters].

The Altoids tin has long been the enclosure of choice for those seeking to show off their miniaturization chops. This is especially true for amateur radio homebrewers — you really have to know what you’re doing to stuff a complete radio in a tiny tin. But when you can build an entire 80-meter transceiver in a matchbox, that’s a whole other level of DIY prowess.

It’s no surprise that this one comes to us from [Helge Fykse (LA6NCA)], who has used the aforementioned Altoids tin to build an impressive range of “spy radios” in both vacuum tube and solid-state versions. He wisely chose solid-state for the matchbox version of the transceiver, using just three transistors and a dual op-amp in a DIP-8 package. There’s also an RF mixer in an SMD package; [Helge] doesn’t specify the parts, but it looks like it might be from Mini-Circuits. Everything is mounted dead bug style on tiny pieces of copper-clad board that get soldered to a board just the right size to fit in a matchbox.

A 9 volt battery, riding in a separate matchbox, powers the rig. As do the earbud and tiny Morse key. That doesn’t detract from the build at all, and neither does the fact that the half-wave dipole antenna is disguised as a roll of fishing line. [Helge]’s demo of the radio is impressive too. The antenna is set up very low to the ground to take advantage of near vertical incidence skywave (NVIS) propagation, which tends to direct signals straight up into the ionosphere and scatter them almost directly back down. This allows for medium-range contacts like [Helge]’s 239 km contact in the video below.

Banging out Morse with no sidetone was a challenge, but it’s a small price to pay for such a cool build. We’re not sure how much smaller [Helge] can go, but we’re eager to see him try.

If you don’t know Morse code, you probably think of a radio operator using a “key” to send Morse code. These were — and still are — used. They are little more than a switch built to be comfortable in your hand and spring loaded so the switch makes when you push down and breaks when you let up. Many modern operators prefer using paddles along with an electronic keyer, but paddles can be expensive. [N1JI] didn’t pay much for his, though. He took paperclips, a block of wood, and some other scrap bits and made his own paddles. You can see the results in the video below.

When you use a key, you are responsible for making the correct length of dits and dahs. Fast operators eventually moved to a “bug,” which is a type of paddle that lets you push one way or another to make a dash (still with your own sense of timing). However, if you push the other way, a mechanical oscillator sends a series of uniform dots for as long as you hold the paddle down.

Modern paddles tend to work with electronic “iambic” keyers. Like a bug, you push one way to make dots and the other way to make dashes. However, the dashes are also perfectly timed, and you can squeeze the paddle to make alternating dots and dashes. It takes a little practice, but it results in a more uniform code, and most people can send it faster with a “sideswiper” than with a straight key.

Don’t like radio? Use Morse Code as your keyboard. Want to learn code? It isn’t as hard as you think.

We were sad to hear that after 52 years in operation, iconic ham radio supplier MFJ will close next month. On the one hand, it is hard not to hear such news and think that it is another sign that ham radio isn’t in a healthy space. After all, in an ideal world, [Martin Jue] — the well-known founder of MFJ — would have found an anxious buyer. Not only is the MFJ line of ham radio gear well regarded, but [Martin] had bought other ham radio-related companies over the years, such as Ameritron, Hygain, Cushcraft, Mirage, and Vectronics. Now, they will all be gone, too.

However, on a deeper reflection, maybe we shouldn’t see it as another nail in ham radio’s coffin. It is this way in every industry. There was a time when it was hard to imagine ham radio without, say, Heathkit. Yet they left, and the hobby continued. We could name a slew of other iconic companies that had their day: Eico, Hammarlund, Hallicrafters, and more. They live on at hamfests, their product lines are frozen in time, and we’re sure we’ll see a used market for MFJ gear well into the next century.

Maybe you aren’t a ham and wonder why you would care. Turns out MFJ made things of interest to anyone who worked with RF transmitting or receiving. If you were a shortwave listener, they had antennas and related gear for you. They also made antenna analyzers and network analyzers that were very cost-effective compared to other options. If you wanted clean power supplies, MFJ had quite the selection of those. They even had a great selection of variable capacitors and inductors, which are tough to find in small quantities. You could even get air-wound coil stock, knobs, meters, and toroids.

Sure, most of what they sold was things only hams or other radio operators wanted—that was the nature of the company. But their loss will be felt by more than just the ham community. Someone, of course, will step into the void as they always do.

So farewell MFJ. We will miss you, but we look forward to meeting your replacement, whoever that might be. While you can spend a lot of money on ham radio, you can get started for $50 or less. Oddly, we haven’t directly featured much MFJ gear on Hackaday over the years, but we have mentioned a few.

Like most waves in the electromagnetic spectrum, radio waves tend to bounce off of various objects. This can be frustrating to anyone trying to use something like a GMRS or LoRa radio in a dense city, for example, but these reflections can also be exploited for productive use as well, most famously by radar. Radar has plenty of applications such as weather forecasting and various military uses. With some software-defined radio tools, it’s also possible to use radar for tracking aircraft in real-time at home like this DIY radar system.

Unlike active radar systems which use a specific radio source to look for reflections, this system is a passive radar system that uses radio waves already present in the environment to track objects. A reference antenna is used to listen to the target frequency, and in this installation, a nine-element Yagi antenna is configured to listen for reflections. The radio waves that each antenna hears are sent through a computer program that compares the two to identify the reflections of the reference radio signal heard by the Yagi.

Even though a system like this doesn’t include any high-powered active elements, it still takes a considerable chunk of computing resources and some skill to identify the data presented by the software. [Nathan] aka [30hours] gives a fairly thorough overview of the system which can even recognize helicopters from other types of aircraft, and also uses the ADS-B monitoring system as a sanity check. Radar can be used to monitor other vehicles as well, like this 24 GHz radar module found in some modern passenger vehicles.