The regenerative radio is long-ago superseded in commercial receivers, but it remains a common project for electronics or radio enthusiasts seeking to make a simple receiver. It’s most often seen for AM band receivers or perhaps shortwave ham band ones, but it’s a circuit which also works at much higher frequencies. [Perian Marcel] has done just this, with a regenerative receiver for the FM broadcast band.

The principle of a regenerative receiver is that it takes a tuned radio frequency receiver with a wide bandwidth and poor performance, and applies feedback to the point at which the circuit is almost but not quite oscillating. This has the effect of hugely increasing the “Q”, or quality factor of the receiver, giving it much more sensitivity and a narrow bandwidth. They’re tricky to tune but they can give reasonable performance, and they will happily slope-demodulate an FM transmission.

This one uses two tubes from consumer grade TV receivers, the “P” at the start of the part number being the giveaway for a 300mA series heater chain. The RF triode-pentode isn’t a radio part at all, instead it’s a mundane TV field oscillator part pushed into service at higher frequencies, while the other triode-pentode serves as an audio amplifier. The original circuit from which this one is adapted is available online, All in all it’s a neat project, and a reminder that exotic parts aren’t always necessary at higher frequencies. The video is below the break.

As far as hobbies go, ham radio tends to be on the more expensive side. A dual-band mobile radio can easily run $600, and a high-end HF base station with the capability of more than 100 watts will easily be in the thousands of dollars. But, like most things, there’s an aspect to the hobby that can be incredibly inexpensive and accessible to newcomers. Crystal radios, for example, can be built largely from stuff most of us would have in our parts drawers, CW QRP radios don’t need much more than that, and sometimes even the highest-performing antennas are little more than two lengths of wire.

For this specific antenna, [W3CT] is putting together an inverted-V which is a type of dipole antenna. Rather than each of the dipole’s legs being straight, the center is suspended at some point relatively high above ground with the two ends closer to the earth. Dipoles, including inverted-Vs, are resonant antennas, meaning that they don’t need any tuning between them and the radio so the only thing needed to match the antenna to the feed line is a coax-to-banana adapter. From there it’s as simple as attaching the two measured lengths of wire for the target band and hoisting the center of the antenna up somehow. In [W3CT]’s case he’s using a mast which would break the $8 budget, but a tree or building will do just as well.

The video on the construction of this antenna goes into great detail, so if you haven’t built a dipole yet or you’re just getting started on your ham radio journey, it’s a great place to get started. From there we’d recommend checking out an off-center-fed dipole which lets a dipole operate efficiently on multiple bands instead of just one, and for more general ham radio advice without breaking the bank we’d always recommend the $50 Ham series.

The Quansheng UV-K5 is a popular handheld radio. It’s useful out of the box, but also cherished for its modification potential. [OM0ET] purchased one of these capable VHF/UHF radios, but got to hacking—as he wanted to use it as a desktop radio instead!

This might just sound like a simple reshell, but there was actually a bit of extra work involved. Most notably, the Quansheng is designed to be tuned solely by using the keypad. For desktop use, though, that’s actually kind of a pain. Thus, to make life easier, [OM0ET] decided to whip up a little encoder control to handle tuning and other control tasks using an ESP32. This was achieved with help from one [OM0WT] and files for that are on Github. Other tasks involved finding a way to make the keypad work in a new housing, and how to adapt things like the audio and data module and the speaker to their new homes.

Despite the original handheld being much smaller than the case used here, you’d be surprised how tight everything fits in the case. Still, the finished result looks great. We’ve seen some other adaptable and upgradable ham radio gear before, too. Sometimes custom is the way to go! Video after the break.

When all else fails, there’s radio. Hurricane Helene’s path of destruction through Appalachia stripped away every shred of modern infrastructure in some areas, leaving millions of residents with no ability to reach out to family members or call for assistance, and depriving them of any news from the outside world. But radio seems to be carrying the day, with amateur radio operators and commercial broadcasters alike stepping up to the challenge.

On the amateur side, there are stories of operators fixing their downed antennas and breaking out their field day gear to get on the air and start pitching in, with both formal and ad hoc networks passing messages in and out of the affected areas. Critical requests for aid and medication were fielded along with “I’m alright, don’t worry” messages, with reports from the ARRL indicating that Winlink emails sent over the HF bands were a big part of that. Unfortunately, there was controversy too, with reports of local hams being unhappy with unlicensed users clogging up the bands with Baofengs and other cheap radios. Our friend Josh (KI6NAZ) took a good look at the ins and outs of emergency use of the amateur bands, which of course by federal law is completely legal under the conditions. Some people, huh?

Also scoring a win were the commercial broadcasters, especially the local AM stations that managed to stay on the air. WWNC, an AM station out of Nashville, is singled out in this report for the good work they did connecting people through the emergency. As antiquated as it may seem and as irrelevant to most people’s daily lives as it has become, AM radio really proves its mettle when the chips are down. We’ve long been cheerleaders for AM in emergencies, and this has only served to make us more likely to call for the protection of this vital piece of infrastructure.

Windows 10 users, mark your calendars — Microsoft has announced that you’ve got one year to migrate to a more profitable modern operating system. After that, no patches for you! If Microsoft holds true to form, the scope of this “End of Life” will change as the dreaded day draws nearer, especially considering that Windows 10 still holds almost 63% of the Windows desktop market. Will the EOL announcement inspire all those people to migrate? Given a non-trivial fraction of users are still sticking it out with Windows 7, we wouldn’t hold our breath.

Speaking of Microsoft, for as much as they’re the company you love to hate, you’ve got to hand it to them for one product: Microsoft Flight Simulator. It seems like Flight Simulator has been around almost since the Wright Brothers’ day, going through endless updates to keep up with the state of the art and becoming better and better as the years go by. Streaming all that ultra-detailed terrain information comes at a price, though, to the tune of 81 gigabytes per hour for the upcoming Flight Simulator 2024. Your bandwidth may vary, of course, based on how you set up the game and where you’re virtually flying. But still, that number got us thinking: Would it be cheaper to fly a real plane? A lot of us don’t have explicit data caps on our Internet service, but the ISP still will either throttle your bandwidth or start charging per megabyte after a certain amount. Xfinity, for example, charges $10 for each 50GB block you use after reaching 1.2 TB of data in a month, at least for repeat offenders. So, if you were to settle in for a marathon flight, you’d get to fly for free for about 15 hours, after which each hour would rack up about $20 in extra charges. A single-engine aircraft costs anywhere between $120 and $200 to rent, plus the cost of fuel, so it’s still a better deal to fly Simulator, but not by much.

And finally, we were all witness to a remarkable feat of engineering prowess this week with the successful test flight of a SpaceX Starship followed by catching the returning Super Heavy booster. When we first heard about “Mechazilla” and the idea of catching a booster, we dismissed it as another bit of Elon’s hype, like “full self-driving” or “hyperloops.” But damn if we weren’t wrong! The whole thing was absolutely mesmerizing, and the idea that SpaceX pulled off what’s essentially snagging a 20-story building out of the air on mechanical arms was breathtaking. While the close-up videos of the catch are amazing, they don’t reveal a lot about the engineering behind it. Luckily, we’ve got this video by Ryan Hansen Space of the technology behind the catch, lovingly created in Blender. The work seems to have been done before the test flight and was made with a lot of educated guesses, but given how well the renders match up with the real video of the catch, we’d say Ryan nailed it.

Imagine you’ve got an FM transmitter located some place. Wouldn’t it be mighty convenient if you could control that transmitter remotely? That way, you wouldn’t have to physically attend to it every time you had to change some minor parameters! To that end, [Ricardo Lima Caratti] built a rig to do just that.

The build is based around the QN8066—a digital FM transceiver built into a single chip. It’s capable of transmitting and receiving anywhere from 60 MHz to 108 MHz, covering pretty much all global FM stereo radio bands. [Ricardo] paired this chip with an ESP32 for command and control. The ESP32 hosts an HTTP server, allowing the administration of the FM transmitter via a web browser. Parameters like the frequency, audio transmission mode, and Radio Data Service (RDS) information can be controlled in this manner.

It’s a pretty neat little build, and [Ricardo] demonstrates it on video with the radio transmitting some field day content. We’ve seen some other nifty FM transmitters over the years, too. Video after the break.

Sometimes you need to create a satellite navigation tracking device that communicates via a low-power mesh network. [Powerfeatherdev] was in just that situation, and they whipped up a particularly compact solution to do the job.

As you might have guessed based on the name of its creator, this build is based around the ESP32-S3 PowerFeather board. The PowerFeather has the benefit of robust power management features, which makes it perfect for a power-sipping project that’s intended to run for a long time. It can even run on solar power and manage battery levels if so desired. The GPS and LoRa gear is all mounted on a secondary “wing” PCB that slots directly on to the PowerFeather like a Arduino shield or Raspberry Pi HAT. The whole assembly is barely larger than a AA battery.

It’s basically a super-small GPS tracker that transmits over LoRa, while being optimized for maximum run time on limited power from a small lithium-ion cell. If you’re needing to do some long-duration, low-power tracking task for a project, this might be right up your alley.

LoRa is a useful technology for radio communications, as we’ve been saying for some time. Meanwhile, if you’ve got your own nifty radio comms build, or anything in that general milleu, don’t hesitate to drop us a line!

Here’s the thing about radio signals. There is wild and interesting stuff just getting beamed around all over the place. Phrased another way, there are beautiful signals everywhere for those with ears to listen. We go about our lives oblivious to most of them, but some dedicate their time to teasing out and capturing these transmissions.

David Prutchi is one such person. He’s a ham radio enthusiast that dabbles in receiving microwave signals sent from probes in deep space. What’s even better is that he came down to Supercon 2023 to tell us all about how it’s done!

Space Calling

David notes that he’s not the only ham out there doing this. He celebrates the small community of passionate hams that specialize in capturing signals directly from far-off spacecraft. As one of these dedicated enthusiasts, he gives us a look at his backyard setup—full of multiple parabolic dishes for getting the best possible reception when it comes to signals sent from so far away. They’re a damn sight smaller than NASA’s deep space network (DSN) 70-meter dish antennas, but they can still do the job.  He likens trying to find distant space signals as to “watching grass grow”—sitting in front of a monitor, waiting for a tiny little spike to show up on a spectrogram.

The challenge of receiving these signals comes down to simple numbers. David explains that a spacecraft like JUNO emits 28 watts into a 2.5-meter dish, which comes out to roughly 44.5 dBm of signal with a 44.7 dBi gain antenna. The problem is one of distance—it sits at around 715 million kilometers away on its mission to visit Jupiter. That comes with a path loss of around -288 dB. NASA’s 70-meter dish gets them 68 dBi gain on the receive side, which gets them a received signal strength around -131 dBm. To transmit in return, they transmit around the 50-60 kW range using the same antenna. David’s setup is altogether more humble, with a 3.5-meter dish getting him 47 dBi gain. His received signal strength is much lower, around -152 dBm.

His equipment limits what he can actually get from these distant spacecraft. National space agencies can get full signal from their dishes in the tens-of-meters in diameter, sidebands and all. His smaller setup is often just enough to get some of the residual carrier showing up in the spectrogram.  Given he’s not getting full signal, how does he know what he’s receiving is the real deal? It comes down to checking the doppler shift in the spectrogram, which is readily apparent for spacecraft signals. He also references the movie Contact, noting that the techniques in that film were valid. If you move your antenna to point away from the suspected spacecraft, the signal should go away. If it doesn’t, it might be that you’re picking up local interference instead.

THIS. IS. JUST. AWESOME. !!!

This is video decoded from the 8455MHz high rate downlink @uhf_satcom received yesterday. All the work on the decoder and data analysis really paid off in the end!

Video shows solar panel of Chang'e-5 glistening in the sun and dust floating around. pic.twitter.com/FKc92kgskl

— r00t (@r2x0t) November 25, 2020

Some hobbyists have been able to decode video feeds from spacecraft downlinks. 

However, demodulating and decoding full spacecraft signals at home is sometimes possible—generally when the spacecraft are still close to Earth. Some hobbyists have been able to decode telemetry from various missions, and even video signals from some craft! David shows some examples, noting that SpaceX has since started encrypting its feeds after hobbyists first started decoding them.

David also highlights the communications bands most typically used for deep space communication, and explains how to listen in on them. Most of it goes on in the S-band and X-band frequencies, with long-range activity focused on the higher bands.

Basically, if you want to get involved in this kind of thing, you’re going to want a dish and some kind of software defined radio. If you’re listening in S-band, that’s possibly enough, but if you’re stepping up into X-band, you’ll want a downconverter to step that signal down to a lower frequency range, mounted as close to your dish as possible. This is important as X-band signals get attenuated very quickly in even short cable runs. It’s also generally required to lock your downconverter and radio receiver to some kind of atomic clock source to keep them stable. You’ll also want an antenna rotator to point your dishes accurately, based on data you can source from NASA JPL. As for finding downlink frequencies, he suggests looking at the ITU or the Australian Communication and Media Authority website.

He also covers the techniques of optimizing your setup. He dives into the minutae of pointing antennas at the Sun and Moon to pick up their characteristic noise for calibration purposes. It’s a great way to determine the performance of your antenna and supporting setup. Alternatively, you can use signals from geostationary military satellites to determine how much signal you’re getting—or losing—from your equipment.

Ultimately, if you’ve ever dreamed of listening to distant spacecraft, David’s talk is a great place to start. It’s a primer on the equipment and techniques you need to get started, and he also makes it sound really fun, to boot. It’s high-tech hamming at its best, and there’s more to listen to out there than ever—so get stuck in!