Matchbox Transceiver Pushes The Spy Radio Concept To Its Limits

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.

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Open HT Surgery Gives Cheap Transceiver All-Band Capabilities

Watch out, Baofeng; there’s a new kid on the cheap handy talkie market, and judging by this hardware and firmware upgrade to the Quansheng UV-K5, the radio’s hackability is going to keep amateur radio operators busy for quite a while.

Like the ubiquitous Baofeng line of cheap transceivers, the Quansheng UV-K5 is designed to be a dual-band portable for hams to use on the 2-meter VHF and 70-centimeter UHF bands. While certainly a useful capability, these bands are usually quite range-limited, and generally require fixed repeaters to cover a decent geographic area. For long-range comms you want to be on the high-frequency (HF) bands, and you want modulations other than the FM-only offered by most of the cheap HT radios.

Luckily, there’s a fix for both problems, as [Paul (OM0ET)] outlines in the video below. It’s a two-step process that starts with installing a hardware kit to replace the radio’s stock receiver chip with the much more capable Si4732. The kit includes the chip mounted on a small PCB, a new RF choke, and a bunch of nearly invisible capacitors. The mods are straightforward but would certainly benefit from the help of a microscope, and perhaps a little hot air rework. Once the hardware is installed and the new firmware flashed, you have an HT that can receive signals down to the 20-meter band, with AM and SSB modulations, and a completely redesigned display with all kinds of goodies.

It’s important to note that this is a receive-only modification — you won’t be transmitting on the HF bands with this thing. However, it appears that the firmware allows you to switch back and forth between HF receive and VHF/UHF transceive, so the radio’s stock functionality is still there if you need it. But at $30 for the radio and $12 for the kit, who cares? Having a portable HF receiver could be pretty handy in some situations. This looks like yet another fun hack for this radio; we’ve seen a few recently, including a firmware-only band expansion and even a Trojan that adds a waterfall display and a game of Pong. Continue reading “Open HT Surgery Gives Cheap Transceiver All-Band Capabilities”

HF In Small Spaces

Generally, the biggest problem a new ham radio operator will come across when starting out on the high frequency (HF) bands is finding physical space for the antennas. For a quick example, a dipole antenna for the 20 m band will need around 10 m of wire, and the lower frequencies like 80 m need about four times as much linear space. But if you’re willing to trade a large space requirement for a high voltage hazard instead, a magnetic loop antenna might be just the ticket.

Loop antennas like these are typically used only for receiving, but in a pinch they can be used to transmit as well. To tune the antennas, which are much shorter than a standard vertical or dipole, a capacitor is soldered onto the ends, which electrically lengthens the antenna. [OM0ET] is using two loops of coax cable for the antenna, with each end soldered to one half of a dual variable capacitor which allows this antenna to tune from the 30 m bands to the 10 m bands, although he is using it mostly for WSPR on 20 m. His project also includes the use of an openWSPR module, meaning that he doesn’t have to dedicate an entire computer to run this mode.

The main downsides of antennas like these is that they are not omnidirectional, are not particularly good at transmitting, and develop a significantly high voltage across the capacitor as this similar mag loop antenna project demonstrated. But for those with extreme limitations on space or who, like [OM0ET] want a simple, small setup for running low-power applications like WSPR they can really excel. In fact, WSPR is a great mode for getting on the air at an absolute minimum of cost.

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A Ham Radio Answering Machine

For those who grew up with a cell phone in their hand, it might be difficult to imagine a time where the phone wasn’t fully integrated with voicemail. It sounds like a fantastical past, yet at one point a separate machine needed to be attached to the phone to record messages if no one was home to answer. Not only that, but a third device, a cassette tape, was generally needed as a storage device to hold the messages. In many ways we live in a much simpler world now, but in the amateur radio world one group is looking to bring this esoteric technology to the airwaves and [saveitforparts] is demonstrating one as part of a beta test.

The device is called the Boondock Echo, and while at its core it’s an ESP32 there’s a lot going on behind the scenes. It has an audio interface which is capable of connecting to a radio given the correct patch cable; in this case with a simple Baofeng handheld unit. The answering machine can record any sounds that come in. However, with a network connection the recordings are analyzed with an AI which can transcribe what it hears and even listen for specific call signs, then take actions such as sending emails when it hears triggers like that. Boondock also plans for this device to be capable of responding as well, but [saveitforparts] was not able to get this working during this beta test.

While an answering machine might seem like a step backwards technologically, an answering machine like this, especially when paired with Google Voice-like capabilities from an AI, has a lot of promise for ham radio operators. Even during this test, [saveitforparts] lost a radio and a kind stranger keyed it up when it was found, which was recorded by the Boondock Echo and used to eventually recover the radio. Certainly there are plenty of other applications as well, such as using AI instead of something like an Arduino to do Morse decoding.

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A Canned Ham Ham Antenna

If you’d have asked us for odds on whether you could successfully turn a canned ham into an amateur radio antenna, we’d have declined the offer. Now, having seen [Ben Eadie (VE6SFX)]’s “hamtenna” project, we’d look at just about any “Will it antenna?” project with a lot less skepticism than before.

To be painfully and somewhat unnecessarily clear about [Ben]’s antenna, the meat-like product itself is not in the BOM for this build, although he did use it as sustenance. Rather, it was the emptied and cleaned metal can that was the chief component of the build, along with a few 3D printed standoffs and the usual feedline and connectors. This is a slot antenna, a design [Ben] recently experimented with by applying copper foil tape to his car’s sunroof. This time around, the slot was formed by separating the top and bottom of the can using the standoffs and electrically connecting them with a strip of copper tape.

Connected to a stub of coax and a BNC connector, a quick scan with a NanoVNA showed a fantastic 1.26:1 SWR in the center of the 70-cm ham band, and a nearly flat response all the way across the band. Results may vary depending on the size of canned ham you sacrifice for this project; [Ben]’s can measured just about 35 cm around, a happy half-wavelength coincidence. And it actually worked in field tests — he was able to hit a local repeater and got good signal reports. All that and a sandwich? Not too shabby.

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Hands On With Boondock Echo

Perhaps no words fill me with more dread than, “I hear there’s something going around.” In my experience, you hear this when some nasty bug has worked its way into the community and people start getting whatever it is. I’m always on my guard when I hear about something like this, especially when it’s something really unpleasant like norovirus. Forewarned is forearmed, after all.

Since I work from home and rarely get out, one of the principal ways I keep apprised of what’s going on with public health in my community is by listening to my scanner radio. I have the local fire rescue frequencies programmed in, and if “there’s something going around,” I usually find out about it there first; after a half-dozen or so calls for people complaining of nausea and vomiting, you get the idea it’s best to hunker down for a while.

I manage to stay reasonably well-informed in this way, but it’s not like I can listen to my scanner every minute of the day. That’s why I was really excited when my friend Mark Hughes started a project he called Boondock Echo, which aims to change the two-way radio communications user experience by enabling internet-backed recording and playback. It sounded like the perfect system for me — something that would let my scanner work for me, instead of the other way around. And so when Mark asked me to participate in the beta test, I jumped at the chance.

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Pocketable Yagi Antenna Really Shoots For Distance

For amateur radio operators, the quest for the perfect antenna never seems to end. Perhaps that’s because our requirements are always changing. We never quite seem to get to one design that can do everything. This copper-foil Yagi antenna might not do everything, but it really seems to tick off the boxes for gain and directionality along with ultra-portability.

If you’ve been following [Ben Eadie (VE6SFX)]’s trip down the rabbit hole of lightweight antenna building, you’ll recall that he’s already knocked off a J-pole antenna and a stealthy mobile slot antenna using little more than copper foil tape. Both of those designs performed great, but [Ben] had bigger fish to fry: he wanted to build a directional antenna for the 2-meter band and go for distance. The traditional Yagi-Uda is generally the preferred design for beam antennas, but they tend to be bulky and cumbersome. But with a roll of copper foil tape [Ben] was able to lay out a three-element Yagi on a sheet of Tyvek wrap. Reinforced with some packing tape and stiffened with a couple of fiberglass rods attached to a 3D printed handle, and it was ready to go.

[Ben]’s field test results were most impressive. Not only was he able to open up repeaters up to 90 km away, but he was getting good signal reports to boot. He was even able to reach a repeater 150 km distant, just barely though. Still, that’s mighty impressive performance from something that looks like a Union Jack and rolls up to fit in a pocket.

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