Radio Hacks

1430 Articles

Ham Radio Memes In The 1970s

November 11, 2023 by 12 Comments

If you have a fondness for old and unusual ham gear, [Saveitforparts] has a great video (see below) about a Robot slow scan receiver he found at a junk store.  Slow scan or SSTV is a way to send pictures via low-bandwidth audio, such as you often find on the ham bands. The idea is you take a picture, send some squeaks and blips over the air, and in about 8 or 10 seconds, a single frame of video shows up at the receiver. Hams aren’t the only ones who used it. The Apollo missions used an SSTV system in some cases, too.

I’ve been a ham radio operator for a very long time. When I first heard about SSTV, I thought it sounded cool that you could be talking to someone and then show them a picture of your station or your dog or your kids. But when I looked into it, the reality was far different. In the pre-internet days, SSTV-equipped hams hung out on a handful of watering hole frequencies and basically just sent memes and selfies to each other. Everyone would take turns, but there wasn’t really any conversation.

This actually still goes on, but the hardware isn’t a big deal anymore. The Robot in the video had to decode the signal from audio and store the image somehow. On old gear — some of it homebrew — it was simply persistent phosphor that would eventually fade, but, of course, eventually, images were stored in some form of digital memory. These days, you are likely to use a PC soundcard to both send and receive the necessary audio.

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Hands On With Boondock Echo

November 10, 2023 by 23 Comments

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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Machine Teaches Morse Code

November 3, 2023 by 4 Comments

If you are a ham radio operator of a certain age, you probably remember ads for “The Instructograph,” a mechanical device for learning Morse code. [Our Own Devices] has an ancient specimen of the machine and shows us how it works in the video below. The machine is a model of simplicity. You wind up a spring-driven motor like you would for an old record player or music box. A slider sets the playback rate, and paper tape starts to spin.

The paper tape looks like computer tape, but since it only has literal long and short notches, it has two distinct sides. When you learned one set of messages, you could flip the tape over and get more practice that way. How did the machine read the paper tape? With a mechanical contact. Literally, if the paper had a hole in it, you made the circuit. If it didn’t, the circuit was broken. A buzzer and batteries or some other kind of sounder was all you needed.

The company was in business for 50 years. The newer versions had more electronics, but they always used the paper tape mechanism to store the code practice sessions. A 1962 ad noted that the machine could play back the tapes from three words a minute up to 40. You could buy or rent the machine, and we always assumed it was pretty pricey for its day. Around 1965, a new unit would cost $53 but did not include a headset or a key. So that was actually more reasonable than we expected. In 1965, a brand-name clock radio cost about $50, so it wasn’t any more than that.

Everyone has their own favorite method for learning code, especially [Ludwig Koch]. At least you don’t have to learn Alex-style.

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Pocketable Yagi Antenna Really Shoots For Distance

November 2, 2023 by 45 Comments

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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Need A Low-Mass Antenna In Space? Just Blow It Up!

October 31, 2023 by 28 Comments

A parabolic antenna is a simple enough device, a curved reflector designed to focus all the radiation from the direction it’s pointed into a waveguide or antenna at its feedpoint. They’re easy enough to make for a radio amateur, but imagine making one for a spacecraft. It must fold into a minimal space and weigh almost nothing, both difficult to achieve. An engineering academic doing work for NASA, [Christopher Walker], has a new way to make the parabolic surface that solves the spacecraft designer’s problems at a stroke, it forms its parabolic reflector on the inside of an inflatable structure. In this way relatively huge reflectors can be built in space, with easy folding and very little weight. Continue reading “Need A Low-Mass Antenna In Space? Just Blow It Up!” →

A schematic representation of the different ionospheric sub-layers and how they evolve daily from day to night periods. (Credit: Carlos Molina)

Ham Radio Operators’ Ionospheric Science During The Solar Eclipse

October 31, 2023 by 3 Comments

The Earth’s ionosphere is the ionized upper part of the atmosphere, and it’s also the most dynamic as it swells and ebbs depending on whether it’s exposed to the Sun or not. It’s the ionosphere that enables radio frequency communications to reach beyond the horizon, its thickness and composition also affects the range and quality of these transmissions. Using this knowledge, a group of ham radio operators used the October 14 solar eclipse to crowdsource an experiment, as part of the Ham Science Citizen Investigation (HamSCI) community.

A solar eclipse is an interesting consideration with ionospheric RF transmissions, as it essentially creates a temporary period of night time, which is when the ionosphere is the least dense, and thus weakening these transmissions and their total range. As with previous solar eclipses, they turned it into a kind of game, where each ham operator attempts to contact as many others as possible within the least amount of time. Using the collected data points on who was able to talk to whom on the globe, the event’s effect on RF transmissions could be plotted over time. For the August 21, 2017 solar eclipse, the results were published in a 2018 paper by N. A. Frissell et al. in Geophysical Research Letters.

One point which they wished to examine during the 2023 solar eclipse were the plasma bubbles that form near the Earth’s magnetic equator, in regions like Brazil. These plasma bubbles cause a lot of interference, which in the preliminary data can be seen as a clear Doppler shift of the signal due to the diffusion of the ionosphere as the eclipse’s effect took hold. For the next solar eclipse in April 2024 another experiment is scheduled, which will give even more ham radio operators the chance to sign up and contribute to ionospheric science.

Top image: A schematic representation of the different ionospheric sub-layers and how they evolve daily from day to night periods. (Credit: Carlos Molina)

Ham Radio May Speed Up Soon

October 29, 2023 by 14 Comments

The FCC is circulating a proposal for new rules pertaining to amateur radio in the United States. In particular, they want to remove certain baud rate restrictions that have been in place since 1980. It appears the relaxed rules would apply only to some bands, notably some VHF and UHF bands along with the 630 meter and 2200 meter bands, which — we think — are lightly used so far. We’ll save you from grabbing the calculator. That’s around 475 kHz and 136 kHz.

Ham radio operators have long used digital modes like radio teletype and with restrictions on antennas and increasing interference from wireless networking to solar panels and more, digital has become even more popular than in the past. Besides that, cheap computer soundcards make it easier than ever and sophisticated digital modulation techniques have long left the old, clunky TeleType in the dust.

However, the FCC currently limits the baud rate to 300 baud or less, ostensibly to restrict signal bandwidth. No one wants to have an entire band consumed by a 10 Gb RF network. However, modern techniques often squeeze more into less and the FCC will finally recognize that by converting the limit to signal bandwidth, not baud rate.

What’s the bandwidth? For the common bands, it sounds like 2.8 kHz is the answer. For the VLF bands, they are asking for suggestions. The 2200 meter band isn’t even 2.8 kHz wide to start with!

All this talk makes us want to build something for the 2200 meter band. We better start winding the coil now. Then again, maybe we should go piezo. You know, just in case Thomas Dolby tells us that one of our submarines is missing.