radio

521 Articles

Humble Television Tubes Make An FM Regenerative Radio

November 4, 2024 by No comments

The regenerative radio is long-ago superseded in commercial receivers, but it remains a common project for electronics or radio enthusiasts seeking to make a simple receiver.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.

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Few Things Are Cheaper Than This Antenna

October 31, 2024 by 40 Comments

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.

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Turning A Quansheng Handheld Into A Neat Desktop Transceiver

October 28, 2024 by 18 Comments

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.

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Hackaday Links: October 20, 2024

October 20, 2024 by 44 Comments

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.

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FM Transmitter Remotely Controlled Via ESP32

October 18, 2024 by 13 Comments

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.

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Tiny LoRa GPS Node Relies On ESP32

October 17, 2024 by 10 Comments

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!

Supercon 2023: Receiving Microwave Signals From Deep-Space Probes

October 10, 2024 by 5 Comments

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!

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