The perfect antenna is the holy grail of amateur radio. But antenna tuning is a game of inches, and since the optimum length of an antenna depends on the frequency it’s used on, the mere act of spinning the dial means that every antenna design is a compromise. Or perhaps not, if you build this infinitely adjustable capstan-winch dipole antenna.
Dipoles are generally built to resonate around the center frequency of one band, and with allocations ranging almost from “DC to daylight”, hams often end up with a forest of dipoles. [AD0MZ]’s adjustable dipole solves that problem, making the antenna usable from the 80-meter band down to 10 meters. To accomplish this feat it uses something familiar to any sailor: a capstan winch.
The feedpoint of the antenna contains a pair of 3D-printed drums, each wound with a loop of tinned 18-gauge antenna wire attached to some Dacron cord. These make up the adjustable-length elements of the antenna, which are strung through pulleys suspended in trees about 40 meters apart. Inside the feedpoint enclosure are brushes from an electric drill to connect the elements to a 1:1 balun and a stepper motor to run the winch. As the wire pays out of one spool, the Dacron cord is taken up by the other; the same thing happens on the other side of the antenna, resulting in a balanced configuration.
We think this is a really clever design that should make many a ham happy across the bands. We even see how this could be adapted to other antenna configurations, like the end-fed halfwave we recently featured in our “$50 Ham” series.
Last week we featured a story on the new rules regarding drone identification going into effect in the US. If you missed the article, the short story is that almost all unmanned aircraft will soon need to transmit their position, altitude, speed, and serial number, as well as the position of its operator, likely via WiFi or Bluetooth. The FAA’s rule change isn’t sitting well with Wing, the drone-based delivery subsidiary of megacorporation Alphabet. In their view, local broadcast of flight particulars would be an invasion of privacy, since observers snooping in on Remote ID traffic could, say, infer that a drone going between a pharmacy and a neighbor’s home might mean that someone is sick. They have a point, but how a Google company managed to cut through the thick clouds of irony to complain about privacy concerns and the rise of the surveillance state is mind boggling.
Speaking of regulatory burdens, it appears that getting an amateur radio license is no longer quite the deal that it once was. The Federal Communications Commission has adopted a $35 fee for new amateur radio licenses, license renewals, and changes to existing licenses, like vanity call signs. While $35 isn’t cheap, it’s not the end of the world, and it’s better than the $50 fee that the FCC was originally proposing. Still, it seems a bit steep for something that’s largely automated. In any case, it looks like we’re still good to go with our “$50 Ham” series.
Staying on the topic of amateur radio for a minute, it looks like there will be a new digital mode to explore soon. The change will come when version 2.4.0 of WSJT-X, the program that forms the heart of digital modes like WSPR and FT8, is released. The newcomer is called Q65, and it’s basically a follow-on to the current QRA64 weak-signal mode. Q65 is optimized for weak, rapidly fading signals in the VHF bands and higher, so it’s likely to prove popular with Earth-Moon-Earth fans and those who like to do things like bounce their signals off of meteor trails. We’d think Q65 should enable airliner-bounce too. We’ll be keen to give it a try whenever it comes out.
Look, we know it’s hard to get used to writing the correct year once a new one rolls around, and that time has taken on a relative feeling in these pandemic times. But we’re pretty sure it isn’t April yet, which is the most reasonable explanation for an ad purporting the unholy coupling of a gaming PC and mass-market fried foods. We strongly suspect this is just a marketing stunt between Cooler Master and Yum! Brands, but taken at face value, the KFConsole — it’s not a gaming console, it’s at best a pre-built gaming PC — is supposed to use excess heat to keep your DoorDashed order of KFC warm while you play. In a year full of incredibly stupid things, this one is clearly in the top five.
And finally, it looks like we can all breathe a sigh of relief that our airline pilots, or at least a subset of them, aren’t seeing things. There has been a steady stream of reports from pilots flying in and out of Los Angeles lately of a person in a jetpack buzzing around. Well, someone finally captured video of the daredevil, and even though it’s shaky and unclear — as are seemingly all videos of cryptids — it sure seems to be a human-sized biped flying around in a standing position. The video description says this was shot by a flight instructor at 3,000 feet (914 meters) near Palos Verdes with Catalina Island in the background. That’s about 20 miles (32 km) from the mainland, so whatever this person is flying has amazing range. And, the pilot has incredible faith in the equipment — that’s a long way to fall in something with the same glide ratio as a brick.
Fox hunting, or direction finding, is a favorite pastime in the ham radio community where radio operators attempt to triangulate the position of a radio transmission. While it may have required a large amount of expensive equipment in the past, like most ham radio operations the advent of software-defined radio (SDR) has helped revolutionize this aspect of the hobby as well. [Aaron] shows us how to make use of SDR for direction finding using his custom SDR-based Linux distribution called DragonOS.
We have mentioned DragonOS before, but every iteration seems to add new features. This time it includes implementation of a software package called DF-Aggregator. The software (from [ckoval7]), along with the rest of DragonOS, is loaded onto a set of (typically at least three) networked Raspberry Pis. The networked computers can communicate information about the radio waves they receive, and make direction finding another capable feature found in this distribution.
[Aaron] has a few videos showing the process of setting this up and using it, and all of the software is available for attempting something like this on your own. While the future of ham radio as a hobby does remain in doubt, projects like this which bring classic ham activities to the SDR realm really go a long way to reviving it.
A solar eclipse is coming up in just a few weeks, and although with its path of totality near the southern tip of South America means that not many people will be able to see it first-hand, there is an opportunity to get involved with it even at an extreme distance. PhD candidate [Kristina] and the organization HamSCI are trying to learn a little bit more about the effects of an eclipse on radio communications, and all that is required to help is a receiver capable of listening in the 10 MHz range during the time of the eclipse.
It’s well-known that certain radio waves can propagate further depending on the time of day due to changes in many factors such as the state of the ionosphere and the amount of solar activity. What is not known is specifically how the paths can vary over the course of the day. During the eclipse the sun’s interference is minimized, and its impact can be more directly measured in a more controlled experiment. By tuning into particular time stations and recording data during the eclipse, it’s possible to see how exactly the eclipse impacts propagation of these signals. [Kristina] hopes to take all of the data gathered during the event to observe the doppler effect that is expected to occur.
The project requires a large amount of volunteers to listen in to the time stations during the eclipse (even if it is not visible to them) and there are only a few more days before this eclipse happens. If you have the required hardware, which is essentially just a receiver capable of receiving upper-sideband signals in 10 MHz range, it may be worthwhile to give this a shot. If not, there may be some time to cobble together an SDR that can listen in (even an RTL-SDR set up for 10 MHz will work) provided you can use it to record the required samples. It’s definitely a time that ham radio could embrace the hacker community.
Amateur radio operators and shortwave listeners have a common enemy: QRM, which is ham-speak for radio frequency interference caused by man-made sources. Indiscriminate, often broadband in nature, and annoying as hell, QRM spews forth from all kinds of sources, and can be difficult to locate and fix.
But [Emilio Ruiz], an operator from Mexico, got a little help from Mother Nature recently in his quest to lower his noise floor. Having suffered from a really annoying blast of RFI across wide swaths of the radio spectrum for months, a summer thunderstorm delivered a blessing in disguise: a power outage. Hooking his rig up to a battery — all good operators are ready to switch to battery power at a moment’s notice — he was greeted by blessed relief from all that noise. Whatever had caused the problem was obviously now offline.
Rather than waste the quiet time on searching down the culprit, [Emilio] worked the bands until the power returned, and with it the noise. He killed the main breaker in the house and found that the noise abated, leading him on a search of the premises with a portable shortwave receiver. The culprit? Unsurprisingly, it was a cheap laptop power supply. [Emilio] found that the switch-mode brick was spewing RFI over a 200-meter radius; a dissection revealed that the “ferrite beads” intended to suppress RFI emissions were in fact just molded plastic fakes, and that the cord they supposedly protected was completely unshielded.
We applaud [Emilio]’s sleuthing for the inspiration it gives to hunt down our own noise-floor raising sources. It kind of reminds us of a similar effort by [Josh (KI6NAZ)] a while back.
As popular as the venerable Yaesu FT-817 transceiver might be with amateur radio operators, it’s not without its flaws, particularly in the user interface department. [Andy (G7UHN)] is painfully familiar with these flaws, so he designed this auxiliary display and control panel for the FT-817 to make operating it a little easier.
There are a ton of ways to enjoy ham radio, but one of the more popular ways is to bust out of the shack and operate in the great outdoors. From the seashore to mountain peaks, hams love giving their rigs some fresh air and sunshine. The battery-powered, multimode, all-band FT-817 is great for these jaunts, but to fit as much radio into a small package as they did, Yaesu engineers had to compromise on the controls. Rather than bristling with buttons, many of the most-used features of the radio are buried within menus that require multiple clicks and twists to access.
[Andy]’s solution is a PCB bearing an Arduino Nano, an LCD screen, and a whole bunch of actual buttons. The board sits on top of the case and talks to the radio over a 8-pin mini-DIN cable using both documented and undocumented CAT, or Computer Aided Transceiver commands. The LCD displays the current status of various features and the buttons provide easy access to changing them, essentially by sending keystrokes to the radio.
Hats off to [Andy] for tackling this project. The only other FT-817 hack we’ve seen before was useful but far simpler, and didn’t require KiCad, which [Andy] had to teach himself for this one.
Amateur radio operators like to say that working a contact in space can be done with a simple handheld transceiver and a homemade antenna. And while that’s true, it’s true only for low Earth orbit satellites such as the ISS. If you want to reach a satellite in geosynchronous orbit it’ll take a little more effort, and this dual-feed helical “ice cream cone” antenna could really help.
Until recently, the dream of an amateur radio repeater in geosynchronous orbit remained out of reach, but that changed with the launch of the Qatari satellite Es’hail-2 last year. Since then, hams from Brazil to Thailand have been using the repeater, and UK-based [Tech Minds] has been in the thick of the action. The antenna he presents is a hybrid design, needed because of the 2.4-GHz band uplink and 10-GHz downlink on the satellite, also known as QO-100. Both require a largish dish antenna, with the downlink requiring a low-noise block downconverter (LNB) and feed horn. The uplink side of [Tech Minds]’ antenna is a helical design, with three-and-a-half turns of heavy copper wire and a tuning section of copper strapping that attaches directly to an N-type connector. The helix is just the right size for the feed horn of an LNB for the downlink side, nestled in a hole in the helical antenna’s aluminum reflector disc. There are 3D-printed parts to support everything, plus a cone-shaped radome to keep it all safe from the elements.
It looks like a great design, but sadly, North American and East Asian hams can only dream about building one, since QO-100 is below the horizon for us. We’re jealous, but we’re still glad the repeater is up there. Check out this article for more on how Es’hail-2 got the first geosynchronous ham repeater.
