Helping Secure Amateur Radio’s Digital Future

July 15, 2022 by Tom Nardi 54 Comments

The average person’s perception of a ham radio operator, assuming they even know what that means, is more than likely some graybeard huddled over the knobs of a war-surplus transmitter in the wee small hours of the morning. It’s a mental image that, admittedly, isn’t entirely off the mark in some cases. But it’s also a gross over-simplification, and a generalization that isn’t doing the hobby any favors when it comes to bringing in new blood.

In reality, a modern ham’s toolkit includes a wide array of technologies that are about as far away from your grandfather’s kit-built rig as could be — and there’s exciting new protocols and tools on the horizon. To ensure a bright future for amateur radio, these technologies need to be nurtured the word needs to be spread about what they can do. Along the way, we’ll also need to push back against stereotypes that can hinder younger operators from signing on.

On the forefront of these efforts is Amateur Radio Digital Communications (ARDC), a private foundation dedicated to supporting amateur radio and digital communication by providing grants to scholarships, educational programs, and promising open source technical projects. For this week’s Hack Chat, ARDC Executive Director Rosy Schechter (KJ7RYV) and Staff Lead John Hays (K7VE) dropped by to talk about the future of radio and digital communications.

Rosy kicked things off with a brief overview of ARDC’s fascinating history. The story starts in 1981, when Hank Magnuski had the incredible foresight to realize that amateur radio packet networks could benefit from having a dedicated block of IP addresses. In those early days, running out of addresses was all but unimaginable, so he had no trouble securing 16.7 million IPs for use by licensed amateur radio operators. This block of addresses, known as AMPRNet and then later 44Net, was administered by volunteers until ARDC was formed in 2011 and took over ownership. In 2019, the decision was made to sell off about four million of the remaining IP addresses — the proceeds of which went into an endowment that now funds the foundation’s grant programs.

So where does the money go? The ARDC maintains a list of recipients, which provides for some interesting reading. The foundation has helped fund development of GNU Radio, supported the development of an open hardware CubeSat frame by the Radio Amateur Satellite Corporation (AMSAT), and cut a check to the San Francisco Wireless Emergency Mesh to improve communications in wildfire-prone areas. They even provided $1.6 million towards the restoration of the MIT Radio Society’s radome and 18-foot dish.

Of all the recipients of ARDC grants, the M17 project garnered the most interest during the Chat. This community of open source developers and radio enthusiasts is developing a next-generation digital radio protocol for data and voice that’s unencumbered by patents and royalties. In their own words, M17 is focused on “radio hardware designs that can be copied and built by anyone, software that anyone has the freedom to modify and share to suit their own needs, and other open systems that respect your freedom to tinker.” They’re definitely our kind of folks — we first covered the project in 2020, and are keen to see it develop further.

John says the foundation has approximately $6 million each year they can dole out, and that while there’s certainly no shortage of worthwhile projects to support as it is, they’re always looking for new applicants. The instructions and guides for grant applications are still being refined, but there’s at least one hard requirement for any project that wants to be funded by the ARDC: it must be open source and available to the general amateur population.

Of course, all this new technology is moot if there’s nobody to use it. It’s no secret that getting young people interested in amateur radio has been a challenge, and frankly, it’s little surprise. When a teenager can already contact anyone on the planet using the smartphone in their pocket, getting a ham license doesn’t hold quite the same allure as it did to earlier generations.

Depending on how old you are, this might have been one of the most shocking moments in *Stranger Things*.

The end result is that awareness among youth is low. During the Chat, one participant recounted how he had to put Netflix’s Stranger Things on pause so he could explain to his teenage son how the characters in the 1980s set show were able to communicate across long distances using a homemade radio. Think about that for a minute — in a show about nightmarish creatures invading our world from an alternate dimension, the hardest thing for this young man to wrap his head around was the fact a group of teenagers would be able to keep in touch with each other without the Internet or phone lines to connect them.

So its no surprise that John says the ARDC is actively looking for programs which can help improve the demographics of amateur radio. The foundation is looking to not only bring younger people onboard, but also reach out to groups that have been traditionally underrepresented in the hobby. As an example, he points to a grant awarded to the Bridgerland Amateur Radio Club (BARC) last year to bolster their youth engagement program. Funds went towards putting together a portable rig that would allow students to communicate with the International Space Station, and the development of hands-on workshops where teens will be able to launch, track, and recover payloads on a high altitude balloon. Let’s see them do that on their fancy new smartphone.

We want to not only thank Rosy Schechter and John Hays for taking part in this week’s Hack Chat, but everyone else at Amateur Radio Digital Communications for their efforts to support the present and future of amateur radio and digital communication.

The Hack Chat is a weekly online chat session hosted by leading experts from all corners of the hardware hacking universe. It’s a great way for hackers connect in a fun and informal way, but if you can’t make it live, these overview posts as well as the transcripts posted to Hackaday.io make sure you don’t miss out.

Bringing Some Discipline To An SDR Transmitter

July 13, 2022 by Dan Maloney 16 Comments

The proliferation of software-defined radio (SDR) technology has been a godsend for RF hobbyists. SDR-based receivers and transmitters have gotten so cheap that you’ve probably got a stick or two lying around your bench right now — we can see three from where we sit, in fact.

But cheap comes at a price, usually in the form of frequency stability, which can be prohibitive in some applications — especially amateur radio, where spectrum hygiene is of the utmost concern. So we were pleased to see [Tech Minds] tackle the SDR frequency stability problem by using a GPS-disciplined oscillator. The setup uses an ADALM-PLUTO SDR transceiver and a precision oscillator from Leo Bodnar Electronics. The oscillator can be programmed to output a rock-solid, GPS-disciplined signal over a wide range of frequencies. The Pluto has an external oscillator input that looks for 40 MHz, which is well within the range of the GPSDO.

Setup is as easy as plugging the oscillator’s output into the SDR’s external clock input using an SMA to UFL jumper, and tweaking the settings in the SDR and oscillator. Not all SDRs will have an external clock input, of course, so your mileage may vary. But if your gear is suitably equipped, this looks like a great way to get bang-on frequency — the video below shows just how much the undisciplined SDR can drift.

Like any good ham, [Tech Minds] is doing his bit to keep his signals clean and on target. His chief use case for this setup will be to work QO-100, amateur radio’s first geosynchronous satellite repeater. We’ve got to say that we hams living on the two-thirds of the globe not covered by this satellite are just dying to get a geosynchronous bird (or two) of our own to play with like this.

Continue reading “Bringing Some Discipline To An SDR Transmitter” →

Wind-Up Tape Measure Transformed Into Portable Ham Antenna

March 30, 2022 by Dan Maloney 21 Comments

If there’s one thing that amateur radio operators are good at, it’s turning just about anything into an antenna. And hams have a long history of portable operations, too, where they drag a (sometimes) minimalist setup of gear into the woods and set up shop to bag some contacts. Getting the two together, as with this field-portable antenna made from a tape measure, is a double win in any ham’s book.

For [Paul (OM0ET)], this build seems motivated mainly by the portability aspect, and less by the “will it antenna?” challenge. In keeping with that, he chose a 50-meter steel tape measure as the basis of the build. This isn’t one of those retractable tape measures, mind you — just a long strip of flexible metal on a wind-up spool in a plastic case. His idea was to use the tape as the radiator for an end-fed halfwave, or EFHW, antenna, a multiband design that’s a popular option for hams operating from the 80-m band down to the 10-m band. EFHW antennas require an impedance-matching transformer, a miniature version of which [Paul] built and tucked within the tape measure case, along with a BNC connector to connect to the radio and a flying lead to connect to the tape.

Since a half-wave antenna is half the length of the target wavelength, [Paul] cut off the last ten meters of the tape to save a little weight. He also scratched off the coating on the tape at about the 40-meter mark, to make good contact with the alligator clip on the flying lead. The first video below details the build, while the second video shows the antenna under test in the field, where it met all of the initial criteria of portability and ease of deployment.

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Boat Anchor Twins Get A Little Digital Help Staying On Frequency

March 11, 2022 by Dan Maloney 9 Comments

In the ham radio trade, gear such as the old Drake units [Dr. Scott M. Baker] has in his radio shack are often referred to as “boat anchors.” It refers to big, heavy radios that were perhaps a bit overengineered compared to the state of the art at the time they were designed, and it’s actually a shame that the name has taken on something of a pejorative connotation, since some of this gear is rock solid half a century or more after it was built.

But older gear is often harder to use, at least compared to the newer radios with microcontrollers and more stable oscillators inside. To make his 1970s-era Drake “Twins” setup of separate but linked receiver and transmitter a little more fun to use, [Scott] came up with this neat Raspberry Pi-based DDS-VFO project to keep his boat anchors afloat. Compared to the original mechanically tuned variable frequency oscillator in the Drake receiver, the direct-digital synthesis method promises more stability, meaning less knob-nudging to stay on frequency.

The hardware used for the DDS-VFO is actually pretty simple — just a Raspberry Pi Zero W driving an AD9850-based signal-generator module. Sending the signal to the Twins was another matter. That was done by tapping into the injection cable linking both units, which meant a few circuit complications to deal with signal attenuation. [Scott] also added amenities like a digital frequency display, optical encoder with crank-style knob to change frequency, and a host of Cherry MX keyswitches for quick access to different features.

From the look of the video below, the Twins are now rock-solid and a lot easier to use. This project is loosely based on a recent panadapter project [Scott] undertook for the receiver side of the Twins.

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Retro And New Tech Combine In This Hybrid Ham Transmitter

February 27, 2022 by Dan Maloney 9 Comments

We’ve said it before and we’ll say it again: the best part about holding an amateur radio license is that it lets you build and use your own transmitting equipment. Hams have been doing this for more than a century — indeed, it was once the only way to get on the air — using whatever technology was available. But the mix of technologies in this low-power transmitter for the 80-meter band is something you don’t see every day.

As ham [Helge Fykse (LA6NCA)] describes in the video below, the project began when he came into possession of a bonanza of vacuum tubes — 12A6 tetrodes, specifically. The new-old-stock tubes were perfect for an RF power amplifier, but that left the problem of what to use for an oscillator. [Helge] chose to meld the old with the new and used oscillator board that he designed. The board has an ATmega88 microcontroller and an Si5351 oscillator, along with a 3V3 regulator to let the module run on 12 volts. And for a nice retro touch, [Helge] put the board in a 3D printed case that looks like an old-fashioned quartz crystal.

There are some other nice design touches here too. A low-pass filter cleans up the harmonics of the oscillator’s 3.5-MHz square wave output before feeding it to the amplifier, in a nod to proper spectrum hygiene. The primary for the amp’s air-core output transformer is hand-wound, with 3D printed spacers to keep the winding neat and even. The tuning process shown below is interesting, and the transmitter was used to make a solid contact with another ham about 100 km away. And we really liked the look of [Helge]’s shack, stuffed as it is with gear both old and new.

We’ve personally tried the Si5351 for QRP transmitters before, but this blend of the old and new really makes us want to find some tubes and get to playing.

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Work The World On A 555

January 13, 2022 by Jenny List 14 Comments

Over the years the humble 555 timer has been used in so many unexpected places, but there’s a project from [Frank Latos] which we think may be a first. On a piece of stripboard sit a pair of 555s, and instead of the usual passives there are a set of LC circuits. This is no timer, instead it’s a CW (Morse) transmitter for the 80 metre amateur radio band.

One 555 is configured as a feedback oscillator through a toroidal transformer with a tuned circuit to set the frequency of oscillation. The other takes an inverted input from the oscillator to produce complimentary push-pull outputs from both 555s, which are fed to another transformer that in turn feeds a low-pass filter and thus the antenna.

Free-running squarewave oscillators of this type are not unusual for the lower HF bands, but we think this is the first 555 design we’ve seen. As shown it doesn’t produce much in the way of RF power, but remembering half-decent motor drivers using a 556 dual timer we think that selection of one of the more powerful 555 variants might deliver some more punch. We commend his creativity though, and hope he can get that all-important entry in the log to prove it works.

If you’re curious about low-power radio operation, it’s something we’ve explored before.

Four Band Digital HF SDR Transceiver Offers High Performance For Only $60

December 8, 2021 by Ryan Flowers 31 Comments

Amateur radio is a hobby that is often thought of as being exclusive to those with a healthy expendable income. In recent years however, the tides have turned. Cheap microcontrollers and signal generators have helped turned things around, and the $60 USD QDX from QRP Labs goes even further by sending the performance/price ratio through the roof. You can see more details in the video below the break.

The QDX is the creation of [Hans Summers] who is well known for producing affordable high performance amateur radio kits that are focused on low power transmission, called “QRP” in ham radio parlance. What is it? It’s a pocket sized four band (80, 40, 30, 20 Meters) software defined radio (SDR) that is designed to be used with some of the most popular digital radio modes: FT8 and JS8Call, as well as any other FSK based mode such as RTTY. It’s also been tested to work well (and within spec) on 60 Meters.

While classic radios have to be connected to a computer through a special hardware interface, the QDX is designed to connect directly to a computer through a standard USB A>B cable. CAT control, PTT, and Audio are all handled directly by the QDX, and no special interface is needed. While the radio is essentially plug and play, configuration, testing, and troubleshooting can be done by connecting to the QDX’s unique serial console, which among other things contains a text based waterfall. For those who want to run their own SDR receiver, I/Q output can be sent directly through the sound card.

Now for the bad news: due to global chip shortages, the QDX is out of stock at the moment, and there’s no telling when they might start shipping again. QRP Labs is looking to source parts wherever they can to get more of the units made, but of course, so is everyone else right now. Continue reading “Four Band Digital HF SDR Transceiver Offers High Performance For Only $60” →