It’s been a long time since vacuum tubes were cutting-edge technology, but that doesn’t mean they don’t show up around here once in a while. And when they do, we like to feature them, because there’s still something charming, nay, romantic about a circuit built around hot glass and metal. To wit, we present this compact two-tube “spy radio” transmitter.
From the look around his shack — which we love, by the way — [Helge Fykse (LA6NCA)] really has a thing for old technology. The typewriter, the rotary phones, the boat-anchor receiver — they all contribute to the retro feel of the space, as well as the circuit he’s working on. The transmitter’s design is about as simple as can be: one tube serves as a crystal-controlled oscillator, while the other tube acts as a power amplifier to boost the output. The tiny transmitter is built into a small metal box, which is stuffed with the resistors, capacitors, and homebrew inductors needed to complete the circuit. Almost every component used has a vintage look; we especially love those color-coded mica caps. Aside from PCB backplane, the only real nod to modernity in the build is the use of 3D printed forms for the coils.
But does it work? Of course it does! The video below shows [Helge] making a contact on the 80-meter band over a distance of 200 or so kilometers with just over a watt of power. The whole project is an excellent demonstration of just how simple radio communications can be, as well as how continuous wave (CW) modulation really optimizes QRP setups like this.
When the first radios and telegraph lines were put into service, essentially the only way to communicate was to use Morse code. The first transmitters had extremely inefficient designs by today’s standards, so this was more a practical limitation than a choice. As the technology evolved there became less and less reason to use Morse to communicate, but plenty of amateur radio operators still use this mode including [Kevin] aka [KB9RLW] who has built a circuit which can translate spoken Morse code into a broadcasted Morse radio signal.
The circuit works by feeding the signal from a microphone into an Arduino. The Arduino listens for a certain threshold and keys the radio when it detects a word being spoken. Radio operators use the words “dit” and “dah” for dots and dashes respectively, and the Arduino isn’t really translating the words so much as it is sending a signal for the duration of however long each word takes to say. The software for the Arduino is provided on the project’s GitHub page as well, and uses a number of approaches to make sure the keyed signal is as clean as possible.
[Kevin] mentions that this device could be used by anyone who wishes to operate a radio in this mode who might have difficulty using a traditional Morse key and who doesn’t want to retrain their brain to use other available equipment like a puff straw or a foot key. The circuit is remarkably straightforward for what it does, and in the video below it seems [Kevin] is having a blast using it. If you’re still looking to learn to “speak” Morse code, though, take a look at this guide which goes into detail about it.
When it comes to rendering text input into an electronic form,the newest keyboards use USB for wired interfacing, while the oldest Morse keys use a single conductor. Shall the two ever meet? For [Matthew Sparks] the answer is yes, with his “The Gadget” Morse-to-USB HID interface which presents a Morse key to a computer as though it were a USB keyboard.
At its heart is a Seeduino Arduino clone, upon which the Morse key waggles a pin, and which through the extensive magic of software recognizes the keyed characters and converts them into USB key presses for the computer. It’s thus a surprisingly simple project, and the write-up spends far more time proselytizing the art of the carrier wave than it does on Arduino code.
Morse is simultaneously a manual art form, an efficient means of communicating through congested radio bands, and an anachronism, which probably explains its continued appeal in the radio amateur fraternity. We’re not sure how many keyboard warriors will switch to the single key with this project, but we can see that it might be a useful aid to learning as well as a pretty quick input method for the owner of an experienced fist.
Amateur radio operators have a saying: When all else fails, there’s ham radio. And that’s true, at least to an extent — knock out the power, tear down the phone lines, and burn up all the satellites in orbit, and there will still be hams talking about politics on 40 meters. The point is, as long as the laws of physics don’t change, hams will figure out a way to send and receive messages. In honor of that fact, the police in the city of Pune in Maharashtra, India, make it a point to exchange messages with their headquarter using Morse code once a week. The idea is to maintain a backup system, in case they can’t get a message through any other way. It’s a good idea, especially since they rotate all their radio operators through the Sunday morning ritual. We can’t imagine that most emergency services dispatchers would be thrilled about learning Morse, though.
Just because you’re a billionaire with a space company doesn’t mean you’re an astronaut. At least that’s the view of the US Federal Aviation Administration, which issued guidelines pretty much while Jeff Bezos and his merry band of cohorts were floating about above the 100-km high Kármán line in a Blue Origin “New Shepard” rocket. The FAA guidelines make it clear that those making the trip need to have actually done something to qualify as an astronaut, by “demonstrated activities during flight that were essential to public safety, or contributed to human space flight safety.” That’s good news to the “Old Shepard”, who clearly was in control of “Freedom 7” during the Mercury program. But the Bezos brothers, teenager Oliver Daemen, and Wally Funk, one of the “Mercury 13” group of women who trained to be NASA astronauts but never got to fly, were really just along for the ride, as the entire flight was automated. It doesn’t take away from the fact that they’ve been to space and you haven’t, of course, but they can’t officially call themselves astronauts. This goes to show that even billionaires can just be ballast too.
Good news, everyone — if you had anything that was being transported aboard the Ever Given, your stuff is almost there. The Suez Canal-occluding container ship finally made it to its original destination in Rotterdam, approximately four months later than originally predicted. After plugging up the vital waterway for six days last March, the ship along with her cargo and her crew were detained in Egypt’s Great Bitter Lake, perhaps the coolest sounding body of water in the world next to the Dead Sea. Legal squabbling ensued at that point, all the while rendering whatever was in the 20,000-odd containers aboard the ship pretty much pointless. We’d imagine that even with continuous power, whatever was in the refrigerated containers must be pretty nasty by now, so there’s probably a lot of logistics and clean-up left to sort out.
I have to admit that I have a weird love of explosive bolts. I don’t know what it is, but the idea of fasteners engineered to fail in a predictable way under the influence of pyrotechnic charges just tickles something in me. I mean, I even wrote a whole article on the subject once. So when I came across this video explaining how the Space Shuttles were held to the launch pad, I really had to watch it. Surprisingly, the most interesting part of this story was not the explosive aspect, but the engineering problem of supporting the massive vehicle on the launch pad. For as graceful as the Shuttles seemed once they got into orbit, they really were ungainly beasts, especially strapped to the external fuel tank and booster. The scale of the eight frangible nuts used to secure the boosters to the pad is just jaw-dropping. We also liked the idea that NASA decided to catch the debris from the explosions in a container filled with sand.
What attracts a lot of people to amateur radio is that it gives you the ability to make your own gear. Scratch-building hams usually start by making their own antennas, but eventually, the itch to build one’s own radio must be scratched. And building this one-transistor transmitter is just about the simplest way to dive into the world of DIY radio.
Of course, limiting yourself to eight components in total entails making some sacrifices, and [Kostas (SV3ORA)]’s transmitter is clearly a study in compromise. For starters, it’s only a transmitter, so you’ll need to make other arrangements to have a meaningful conversation. You’ll also have to learn Morse code because the minimalist build only supports continuous-wave (CW) mode, although it can be modified for amplitude modulation (AM) voice work.
The circuit is flexible enough that almost any part can be substituted and the transmitter will still work. Most of the parts are junk-bin items, although the main transformer is something you’ll have to wind by hand. As described, the transformer not only provides feedback to the transistor oscillator, but also has a winding that powers an incandescent pilot lamp, and provides taps for attaching antennas of different impedances — no external tuner needed. [SV3ORA] provides detailed transformer-winding instructions and shows the final build, which looks very professional and tidy. The video below shows the rig in action with a separate receiver providing sidetone; there’s also the option of using one of the WebSDR receivers sprinkled around the globe to verify you’re getting out.
This little transmitter looks like a ton of fun to build, and we may just try it for our $50 Ham series if we can find all the parts. Honestly, the hardest to come by might be the variable capacitor, but there are ways around that too.
You really should learn to read Morse code. But if you can’t — or even if you can, and just want a break — you can always get a computer to do it. For example, [jmharvey1] has a decoder that runs on a cheap Bluepill dev board.
The device uses a touchscreen and a few common components. The whole thing cost about $16. You can see it at work along with a description of the project in the video below.
If you look at the computer in front of you, it will have an array of input devices. A keyboard and mouse, a touch screen, maybe a microphone, or even a gamepad. Each of them will have its moment to shine, and you’ll probably have put some effort into their selection. But when it comes to a computer, almost anything connected to it can be an input device in some form, as long as it provides some form of machine readable parameter.
Consider your laptop: it knows when its lid is closed such that it can put itself to sleep. Even that can be used as an input device with a little ingenuity, as [veggiedefender] has done with “open and shut“, a Morse keyer using opening and closing the laptop lid as its key.
The software for GNU/Linux distributions is a surprisingly accessible set of shell scripts that attach themselves to ACPI events surrounding the lid switch. In use it seems a little cumbersome, but we suspect its real value is not in repeatedly slammin the lid to produce Morse text input. Instead with many lid switches being magnetic reed switches an operator could simply wear a ring with a magnet and tap out their text every bit as quickly as they could using a traditional key.
