Building A Ham Radio Data Transceiver On The Cheap

October 3, 2025 by 19 Comments

Once upon a time, ham radio was all about CW and voice transmissions and little else. These days, the hobby is altogether richer, with a wide range of fancy digital data modes to play with. [KM6LYW Radio] has been tinkering in this space, and whipped up a compact ham radio data rig that you can build for well under $100.

Radio-wise, the build starts with the Baofeng UV-5R handheld radio. It’s a compact VHF/UHF transceiver with 5W output and can be had for under $25 USD if you know where to look. It’s paired with a Raspberry Pi Zero 2W, which is the brains of the operation. The Pi is hooked up to the All-In-One-Cable which is basically a soundcard-like interface that plugs into USB and hooks up to the mic and speaker outputs of the Baofeng handheld. The final pieces of the puzzle are a USB PD battery pack and a small OLED screen to display status information.

What does that kit get you? The capability to transmit on all sorts of digital modes with the aid of the DigiPi software package. You can send emails, jump on APRS, or even chat on the web. You can configure all of this through a web interface running on the Raspberry Pi.

We’ve looked at some interesting digital ham projects before, too. Video after the break.

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The Hottest Spark Plugs Were Actually Radioactive

October 1, 2025 by 57 Comments

In the middle of the 20th century, the atom was all the rage. Radiation was the shiny new solution to everything while being similarly poorly understood by the general public and a great deal of those working with it.

Against this backdrop, Firestone Tire and Rubber Company decided to sprinkle some radioactive magic into spark plugs. There was some science behind the silliness, but it turns out there are a number of good reasons we’re not using nuke plugs under the hood of cars to this day.

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A Ham-Adjacent Portable Radio Repeater

September 26, 2025 by 45 Comments

Although ham radio offers a wide array of bands to transmit on, not to mention plenty of modes to communicate with, not everyone wants or needs to use all of this capability. For those needing simple two-way communication services like FRS or GMRS are available (in North America) with much less stringent licensing requirements, and GMRS even allows repeaters to be used to extend their range beyond the typical mile or so. [Dave] aka [N8DAV] has built an off-grid simplex repeater that can travel around with him wherever he goes.

The repeater itself is based on a pre-built simplex repeater module, which means that it has to record an incoming signal and then play it back on the same frequency. Compared to a split frequency repeater which uses different frequencies for transmit and receive this can be a bit cumbersome but simplifies the design and the use. A Baofeng UV-5R is used to perform the actual radio duties paired to a 40 watt amplifier to extend the range as much as possible. It’s all packed into a Pelican-like case and set up with a large battery that could power it for a number of days, making it useful for camping, rescue, or other off-grid activities.

For those wondering why [Dave] is using his ham call sign instead of his GMRS one, all of the equipment in this build will work in either the UHF ham bands or the channels reserved for GMRS with minor adjustments, so it’s perfectly possible to use the setup for one’s preferred license. And, for those in other parts of the world without GMRS there’s a similar class of radio called UHF CB which might be able to support similar builds, but be sure to check your local jurisdiction’s laws before hooking something like this up. For an even longer-range radio repeater using similar equipment we’d recommend looking to the skies.

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Radio Shack Rebirth May Have Gone Awry In Alleged Ponzi-Like Scheme

September 25, 2025 by 33 Comments

Oh, Radio Shack. What a beautiful place you once were, a commercial haven for those seeking RC cars, resistors, and universal remotes. Then, the downfall, as you veered away from your origins, only to lead to an ultimate collapse. More recently, the brand was supposed to return to new heights online… only to fall afoul of the Securities and Exchange Commission. (via Yahoo Finance, Bloomberg)

The Radio Shack brand was picked up a few years ago by a company known as Retail Ecommerce Ventures (REV). The company’s modus operandi was to take well-known but beleaguered brands and relaunch them as online-only operations. Beyond Radio Shack, REV also owned a number of other notable brand names, like Pier 1, Modell’s Sporting Goods, and Dress Barn.

Unfortunately, the Radio Shack rebirth probably won’t reach the stellar heights of the past. Namely, because REV has been accused of operating a Ponzi-like scheme by the SEC. Despite huge boasts allegedly made to investors, none of REV’s portfolio of brands were actually making profits, and the SEC has charged that the company was paying investor returns with cash raised from other investors — unsustainable, and a major no-no, legally speaking. In any case, the SEC charges apply directly to REV. The RadioShack brand has since been acquired by Unicomer Group, which operates the current online business, and has no ties to REV or its former operators.

We were cautiously optimistic when we heard about the REV buyout back in 2020, but at this point, it’s probably best to come to terms with the fact that Radio Shack won’t be returning to its former glory. The name will linger in our hearts for some time to come, but the business we knew is long gone. Sometimes it’s better to look to the future than to try and recreate the magic of the past, especially if you’re doing inappropriate things with other people’s money in the process.

Meter Mods Make Radioactive Prospecting More Enjoyable

September 24, 2025 by 1 Comment

While we often get a detailed backstory of the projects we cover here at Hackaday, sometimes the genesis of a build is a bit of a mystery. Take [maurycyz]’s radiation survey meter modifications, for instance; we’re not sure why such a thing is needed, but we’re pretty glad we stumbled across it.

To be fair, [maurycyz] does give us a hint of what’s going on here by choosing the classic Ludlum Model 3 to modify. Built like a battleship, these meters would be great for field prospecting except that the standard G-M tube isn’t sensitive to gamma rays, the only kind of radiation likely not to be attenuated by soil. A better choice is a scintillation tube, but those greatly increase the background readings, making it hard to tease a signal from the noise.

To get around this problem and make rockhounding a little more enjoyable, [maurycyz] added a little digital magic to the mostly analog Ludlum. An AVR128 microcontroller taps into the stream of events the meter measures via the scintillation tube, and a little code subtracts the background radiation from the current count rate, translating the difference into an audible tone. This keeps [maurycyz]’s eyes on the rocks rather than on the meter needle, and makes it easier to find weakly radioactive or deeply buried specimens.

If you’re not ready to make the leap to a commercial survey meter, or if you just want to roll your own, we’ve got plenty of examples to choose from, from minimalist to cyberpunkish.

Radio Apocalypse: Clearing The Air With SCATANA

September 18, 2025 by 7 Comments

For the most part, the Radio Apocalypse series has focused on the radio systems developed during the early days of the atomic age to ensure that Armageddon would be as orderly an affair as possible. From systems that provided backup methods to ensure that launch orders would reach the bombers and missiles, to providing hardened communications systems to allow survivors to coordinate relief and start rebuilding civilization from the ashes, a lot of effort went into getting messages sent.

Strangely, though, the architects of the end of the world put just as much thought into making sure messages didn’t get sent. The electronic village of mid-century America was abuzz with signals, any of which could be abused by enemy forces. CONELRAD, which aimed to prevent enemy bombers from using civilian broadcast signals as navigation aids, is a perfect example of this. But the growth of civil aviation through the period presented a unique challenge, particularly with the radio navigation system built specifically to make air travel as safe and reliable as possible.

Balancing the needs of civil aviation against the possibility that the very infrastructure making it possible could be used as a weapon against the U.S. homeland is the purpose of a plan called Security Control of Air Traffic and Air Navigation Aids, or SCATANA. It’s a plan that cuts across jurisdictions, bringing military, aviation, and communications authorities into the loop for decisions regarding when and how to shut down the entire air traffic system, to sort friend from foe, to give the military room to work, and, perhaps most importantly, to keep enemy aircraft as blind as possible. Continue reading “Radio Apocalypse: Clearing The Air With SCATANA” →

Naturally Radioactive Food And Safe Food Radiation Levels

September 17, 2025 by 25 Comments

There was a recent recall of so-called ‘radioactive shrimp’ that were potentially contaminated with cesium-137 (Cs-137). But contamination isn’t an all-or-nothing affair, so you might wonder exactly how hot the shrimp were. As it turns out, the FDA’s report makes clear that the contamination was far below the legal threshold for Cs-137. In addition, not all of the recalled shrimp was definitely contaminated, as disappointing as all of this must be to those who had hoped to gain radioactive Super Shrimp powers.

After US customs detected elevated radiation levels in the shrimp that was imported from Indonesia, entry for it was denied, yet even for these known to be contaminated batches the measured level was below 68 Bq/kg. The FDA limit here is 1,200 Bq/kg, and the radiation level from the potassium-40 in bananas is around the same level as these ‘radioactive shrimp’, which explains why bananas can trigger radiation detectors when they pass through customs.

But this event raised many questions about how sensible these radiation checks are when even similar or higher levels of all-natural radioactive isotopes in foods pass without issues. Are we overreacting? How hot is too hot?

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