A Quick And Stealthy Mobile Slot Antenna From Copper Tape

October 25, 2023 by Dan Maloney 41 Comments

[Ben Eadie (VE6SFX)] is at it again with the foil tape, and this time he’s whipped up a stealthy mobile sunroof antenna for the amateur radio operator with the on-the-go lifestyle.

You may recall [Ben]’s recent duck tape antenna for the 70-cm ham band, an ultra-lightweight design that lends itself to easy packing for portable operation. The conductors in that antenna were made from copper foil tape, a material that’s perfect for all sorts of specialized applications, like the slot antenna that he builds in the video below. In the ham world, slot antennas are most frequently seen cut into the main reflector of a direct satellite dish, often in hopes of avoiding the homeowner association’s antenna police. Even in the weird world of RF, it’s a strange beast because it relies on the absence of material in a large planar (or planar-ish) conductive surface.

Rather than grabbing an angle grinder to make a slot in the roof of his car, [Ben] created a “virtual” slot with copper tape on the inside of his car’s sunroof. His design called for a 39″ (0.99-m) slot, so he laid out a U-shaped slot to fit the window and outlined it with copper foil tape. His method was a little complex; he applied the copper tape to a transparent transfer film first, then stuck the whole thing to the underside of the glass in one go. It didn’t quite go as planned, but as he learned in the duck tape antenna, the copper tape makes it easy to repair mistakes. A BNC connector with pigtails is attached across the slot about 4″ (10 cm) up from the end of one of the short legs of the slot; yes, this looks like a dead short, but such are the oddities of radio.

Is it a great antenna? By the numbers on [Ben]’s NanoVNA, not really. But any antenna that gets you heard is a good antenna, and this one was more than capable in that regard. We’ll have to keep this in mind for impromptu antennas and for those times when secrecy is a good idea.

Continue reading “A Quick And Stealthy Mobile Slot Antenna From Copper Tape” →

This Packable Ham Radio Antenna Is Made From Nothing But Tape

October 13, 2023 by Dan Maloney 46 Comments

On today’s episode of “Will It Antenna?”, [Ben Eadie (VE6SFX)] designs and tests an antenna made entirely of tape, and spoiler alert — it works pretty well.

By way of background, the basic design [Ben] uses here is known as a J-pole, a popular “my first antenna” design for amateur radio operators looking to go beyond the stock whip antenna that comes with that cheap handy-talkie you just can’t resist buying as soon as you get your license. Usually, though, hams will build their J-poles from rigid materials, copper water pipe being a typical choice. Copper has the advantage of being easily sourced, and also results in a self-supporting, weather-resistant antenna that’s easy to mount outdoors. However, copper is getting to be egregiously expensive, and a couple of meters of water pipe isn’t exactly amenable to portable operation, if that’s your jam.

To solve those problems, [Ben] decided to keep his copper use to a minimum with a roll of copper foil tape. He doesn’t provide any specs on the tape, but it looks like it’s about 6 mm (1/4″) wide and judging by a quick Amazon search, probably goes for about $10 a roll. He starts the build with a couple of strips of plain old duck tape — we’ve already had the “duck vs. duct” argument — laid out with the sticky sides together. The copper foil is applied to the duck tape backing using dimensions from any of the J-pole calculators available online. Dimensions are critical to getting good performance from a J-pole, and this is where [Ben]’s tape design shines. Element too long? No problem, just peel up a bit and tear some off. Did you go too far and make an element too short? Easy — just stick on an extension piece of foil. Tuning the location of the feedline connection was a snap, too, with movable terminals held in place with magnets.

Once everything was tuned up, [Ben] soldered down the feed points and covered the foil with a protective layer of duck tape. The antenna performed swimmingly, and aside from costing almost nothing to build, it weighs very little, rolls up to fit in a pack for field operations, and can easily be hoisted into a tree for better coverage. Looks like we’ll be putting in an order for some copper tape and building one of these too. Continue reading “This Packable Ham Radio Antenna Is Made From Nothing But Tape” →

Hackaday Links: October 1, 2023

October 1, 2023 by Dan Maloney 13 Comments

We’ve devoted a fair amount of virtual ink here to casting shade at self-driving vehicles, especially lately with all the robo-taxi fiascos that seem to keep cropping up in cities serving as testbeds. It’s hard not to, especially when an entire fleet of taxis seems to spontaneously congregate at a single point, or all it takes to create gridlock is a couple of traffic cones. We know that these are essentially beta tests whose whole point is to find and fix points of failure before widespread deployment, and that any failure is likely to be very public and very costly. But there’s someone else in the self-driving vehicle business with way, WAY more to lose if something goes wrong but still seems to be nailing it every day. Of course, we’re talking about NASA and the Perseverance rover, which just completed a record drive across Jezero crater on autopilot. The 759-meter jaunt was completely planned by the onboard AutoNav system, which used the rover’s cameras and sensors to pick its way through a boulder-strewn field. Of course, the trip took six sols to complete, which probably would result in negative reviews for a robo-taxi on Earth, and then there’s the whole thing about NASA having a much bigger pot of money to draw from than any start-up could ever dream of. Still, it’d be nice to see some of the tech on Perseverance filtering down to Earth.

Continue reading “Hackaday Links: October 1, 2023” →

Altoids Tin Spy Radio Goes Solid State

September 21, 2023 by Dan Maloney 9 Comments

[Helge Fykse (LA6NCA)] has a type, as they say. At least as far as radios are concerned, he seems to prefer elegant designs that keep the BOM to the minimum needed to get the job done. And Altoids tins — he really seems to like putting radios in Altoids tins.

This QRP transceiver for the 60-meter amateur radio band is a perfect example of that ethos. For the unfamiliar, QRP is Morse code shorthand for decreased power, and is generally used when hams are purposely building and operating radios that radiate very little power, typically below a watt. For this transceiver, [Helge] chose to use modern components, a marked but interesting departure from his recent tube-powered spy radios. The design is centered on a custom oscillator board he designed using an Arduino Pro Mini and an Si5351 oscillator chip. Other components include an ADE-1ASK frequency mixer, an antenna tuner module that can be swapped out for operating on different bands, a receiver that’s little more than a couple of op-amps, and a Darlington pair for an RF power amplifier. Everything fits neatly on a piece of copper-clad board inside the tin box.

As is his tradition, [Helge] was on the air in the field with this radio almost before the solder had time to cool. His first contact was a 240-km shot to a friend, who reported a fine signal from this little gem. And that’s with just powering it off a 9-volt battery when it’s designed to the typical 12-volt supplies hams favor; he estimates this resulted in a signal of about 200 mW. Not too shabby.

Honestly, we’d love to learn more about that oscillator board [Helge] used, and maybe get a schematic for it. We found a little bit about it on his web page, but not the juicy details. If you’re out there, [Helge], please share the wealth.

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All-Mechanical Coil Winder Is A Scrap-Bin Delight

August 30, 2023 by Dan Maloney 10 Comments

If there’s something more tedious than winding coils, we’re not sure what it is — possibly rolling and wrapping coins; that’s really a bother. But luckily, just like there are mechanical ways to count coins, there are tools to make coil production a little less of a chore, but perhaps none that have as much charm as this all-mechanical coil winder.

We’d say that [Ralph (VK3ZZC)]’s amazing invention firmly falls under the “contraption” category, without a hint of the term being used as a pejorative. The rig was based on the MoReCo Coilmaster, a machine that was once commercially available at a fairly steep price, according to [Ralph], and still seems to command a premium even today. Never being able to afford an original, [Ralph] spun up his own from scrap metal and tooling no more sophisticated than a drill press. It’s a riot of brass and steel, with a hand crank that drives the main winding shaft while powering a cam that guides the wire along the long axis of the coil form. Cams can be changed out for different winding patterns, and various chucks adapt to hold different coil forms to the winding shaft.

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Break Free From Proprietary Digital Radio

August 5, 2023 by Bryan Cockfield 51 Comments

Digital modes are all the rage these days in amateur radio — hams are using protocols like WSPR to check propagation patterns, FT8 to get quick contacts on many bands with relatively low power, and MSK144 to quickly bounce a signal off of a meteor. There’s also digital voice, which has a number of perks over analog including improved audio quality. However, the major downside of most digital voice modes, at least those in use on UHF and VHF, is that they are proprietary with various radio brands having competing digital standards. To get above the noise a more open standard can be used instead.

The M17 standard, originally created by [Wojciech Kaczmarski] aka [SP5WWP], uses Codec 2 to convert voice into a digital format before it is broadcast over the air. Codec 2 is an open standard unlike other audio codecs. M17 also supports reflectors, which can link individual radios or entire repeaters together over the Internet. While you can make purpose-built modules that will interface with most standard radio inputs, it’s also possible to modify existing hardware to support this standard as well. The video below from [Tech Minds] shows this being done to a radio with only a few hardware modifications and the installation of a new firmware.

For anyone who has been frustrated that there’s no real universal standard for digital voice in VHF and above, M17 could be a game-changer if enough people get tired of their friends being on other proprietary digital systems. There’s plenty of supported hardware out there that most hams probably already have already, including a number of TNC devices like the Mobilinkd and the DigiRig, so it shouldn’t be too hard to get started. If you’re more into networking over radio, though, take a look at this method for sending high-bandwidth IP networking over the UHF band. Continue reading “Break Free From Proprietary Digital Radio” →

Inexpensive Ham Radio Gets Upgrades Thanks To A Trojan

July 6, 2023 by Dan Maloney 21 Comments

Love them or hate them, the crop of cheap hand-held amateur radio transceivers is here to stay. They’re generally horrible radios, often smearing spurious emissions across the spectrum, but they’re cheap enough to throw in a glove box for emergencies, and they invite experimentation — for instance, modifying the firmware to add functionality the OEM didn’t think to offer.

The new hotness in this class of radios is the Quansheng UV-K5, a two-band transceiver you can pick up for about $40, and we suspect it’ll get hotter still with this firmware trojan by [Piotr (SQ9P)]. We’ve already seen a firmware hack for these radios, one that aimed at unlocking the full frequency range of the RF chip at the heart of the radio. Honestly, we’re not huge fans of these mods, which potentially interfere with other allocations across multiple bands. But [Piotr]’s hacks seem a bit more innocuous, focusing mainly on modifying the radio’s display and adding useful features, such as a calibrated received signal strength bar graph and a numerical RSSI display. The really neat new feature, though, is the spectrum display, which shows activity across a 2-MHz slice of spectrum centered on the currently set frequency. And just because he could, [Piotr] put in a game of Pong.

[Piotr]’s description of the mod as a trojan seems apt since his new programs run in parallel to the OEM firmware by wrapping its vector table. We’d imagine other mods are possible, and we’re keen to see what people come up with for these hackable little units. Just make sure you’re staying within the law, especially in the United States — the FCC does not play games (third item).