Hams Cross The Atlantic On UHF

We often think of ham radio operators talking to exotic faraway lands, and that’s true for hams using the HF bands (below 30 MHz), especially if they have nice antennas. Modern living has made it much harder to have those big antenna farms, and today’s ham is more likely talking on VHF or UHF frequencies with very limited range under normal circumstances. Sure, you can use a repeater or bounce your signal from a satellite or the moon, but normal direct communication is normally going to be less than a typical commercial FM radio station. But on April 7th, two hams communicated across the Atlantic on 432 MHz — a UHF frequency. The distance was almost 4,000 km.

Notice we didn’t say they talked, but they communicated. The contact was via a somewhat controversial mode called FT8 which uses weak signal techniques to allow two computers to send limited amounts of information to each other. However, on April 10, the two stations reported a single sideband voice contact after they noticed the band conditions improving on the FT8 signal.

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Hackaday Links: March 22, 2020

Within the span of just two months, our world of unimaginable plenty and ready access to goods manufactured across the globe has been transformed into one where the bare essentials of life are hard to find at any price. The people on the frontline of the battle against COVID-19 are suffering supply chain pinches too, often at great risk to their health. Lack of proper personal protective equipment (PPE), especially face masks, is an acute problem, and the shortage will only exacerbate the problem as healthcare workers go down for the count. Factories are gearing up to make more masks, but in the meantime, the maker and hacker community can pitch in. FreeSewing, an open-source repository of sewing patterns, has a pattern for a simple face mask called the Fu that can be made quickly by an experienced threadworker. Efficacy of the masks made with that pattern will vary based on the materials used, obviously; a slightly less ad hoc effort is the 100 Million Mask Challenge, where volunteers are given a pattern and enough lab-tested materials to make 100 face masks. If you know how to sew, getting involved might make a difference.

As people around the world wrap their heads around the new normal of social distancing and the loss of human contact, there’s been an understandable spike in interest in amateur radio. QRZ.com reports that the FCC has recorded an uptick in the number of amateur radio licenses issued since the COVID-19 outbreak, and license test prep site HamRadioPrep.com has been swamped by new users seeking to prepare for taking the test. As we’ve discussed, the barrier for entry to ham radio is normally very low, both in terms of getting your license and getting the minimal equipment needed to get on the air. One hurdle aspiring hams might face is the cancellation of so-called VE testing, where Volunteer Examiners administer the written tests needed for each license class. Finding a face-to-face VE testing session now might be hard, but the VEs are likely to find a way to adapt. After all, hams were social distancing before social distancing was cool.

The list of public events that have been postponed or outright canceled by this pandemic is long indeed, with pretty much everything expected to draw more than a handful of people put into limbo. The hacking world is not immune, of course, with many high-profile events scuttled. But we hackers are a resourceful bunch, and the 10th annual Open Source Hardware Summit managed to go off on schedule as a virtual meeting last week. You can watch the nearly eight-hour livestream while you’re self-isolating. We’re confident that other conferences will go virtual in the near-term too rather than cancel outright.

And finally, if you’re sick of pandemic news and just want some escapist engineering eye candy, you could do worse than checking out what it takes to make a DSLR camera waterproof. We’ve honestly always numbered cameras as among the very least waterproof devices, but it turns out that photojournalists and filmmakers are pretty rough on their gear and expect it to keep working even so. The story here focuses (sorry) on Olympus cameras and lenses, which you’ll note that Takasu-san only ever refers to as “splash-proof”, and the complex system of O-rings and seals needed to keep water away from their innards. For our money, the best part was learning that lenses that have to change their internal volume, like zoom lenses, need to be vented so that air can move in and out. The engineering needed to keep water out of a vented system like that is pretty impressive.

Link Coupling Antenna Tuner Wordless Workshop

Remember “Wordless Workshop” in Popular Science? [Roy Doty] illustrated a household problem and the solution for it cobbled up in the main character’s garage workshop. We wonder what [Roy] would have done with YouTube? Maybe something like the video from [VE2TAE] and [VE2AEV] showing their link coupling antenna tuning build. You can watch the video after the break, and if you aren’t a fan of Jazz, you can mute the volume.

Like [Doty’s] cartoons, the video presumes you are going to have your own idea about dimensions and component values to fit your needs. But the construction is beautiful in its own right. The tubing wound into giant coils is impressive and brings back memories of the old days. However, the construction of the variable capacitors really got us excited. Big air variable caps may be hard to find, but the video makes them look easy to make.

A couple of nice looking knobs and panel meters make for a great looking tuner. With that spacing, we imagine it would handle full legal power without any difficulty at all. If you want to learn more about this type of tuner, [VK1OD] had a great page about it which seems to be defunct now. But the Internet Archive comes to our rescue, as usual.

The design is quite old, so even a 1934 copy of “Radio” can explain it (look on page 6). If you want to see a more wordy example of making variable capacitors — although they are smaller, the same principles apply — [N4DFP] has a good write up for that.

Of course, these days, most people expect their antenna tuning to be automatic. With some Lego, though, you could refit your manual one, if you like.

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Learning Morse Code The Ludwig Koch Way

Most countries have dropped the requirement for learning Morse code to become a ham radio operator. Because of that, you might think Morse code is dead. But it isn’t. Some people like the nostalgia. Some like that you can build simple equipment to send and receive Morse code. Others like that Morse code is much more reliable than voice and some older digital modes. Regardless of the reason, many people want to learn Morse code and it is still a part of the ham radio scene. The code has a reputation of being hard to learn, but it turns out that is mostly because people haven’t been taught code in smart ways.

I don’t know if they still do, but some youth organizations used to promote some particularly bad ways to learn the code. The second worse way is to learn “dots and dashes” and many people did learn that way. The very worst way was using an image like the adjacent one to try to map the dots and dashes into letter shapes. This chart dates back to at least 1918 when a Girl Guides handbook printed it.

Even if you are a visual learner, this is a bad idea. The problem is, it is nearly impossible to hear sounds at 20 or 30 words per minute and map them to this visual representation. Another visual method is to use a binary tree where left branches are dots and right branches are dashes.

If you only need to master 5 words per minute to get a merit badge, you might get away with this. But for real use, 5 words a minute is very slow. For example, this sentence would take about 3 minutes to send at that speed. Just that one sentence.

So what are the better ways? Let’s take a look.

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Stout Homebrew Radio Pumps Out 200W Of AM Goodness

In this day and age, with cheap online shopping, software defined radio and bargain-basement Baofengs from China, the upstart radio ham is spoilt for choice. Of course, there’s nothing quite like the charm of keying up your own homebrewed rig, cooked up in the garage from scratch. [Paul], aka [VK3HN], knows just how it feels, and put together an epic 200 watt Class D AM rig to blast his signal on the airwaves.

An example of an Arduino used in one of [Paul]’s builds.
It’s a build following on from the work of another radio ham, [Laurie], aka [VK3SJ]. Younger hackers will note the Arduino Nano at the heart of the project, running the VFO and handling all the relevant transmit/receive switching. We can only imagine how welcome modern microcontrollers must have been to old hands at amateur radio, making synthesizing all manner of wild frequencies a cinch.

The amount of effort that has gone into the build is huge. There are handwound coils for the PWM low-pass filter, and the PCB is home-etched in ferric chloride, doing things the old-school way. There’s also a healthy pile of dead components that sacrificed their lives in the development of this build. Perhaps our favorite part is the general aesthetic – we can’t get over the combination of hand-drawn copper traces and off-the-shelf Arduinos.

Many components perished in the development of this powerful rig.

It’s a build that far exceeds the Australian legal limits, so it only gets keyed up to 120W in real use. This has the benefit of keeping the radio operating far in the safety zone for its components, helping keep things cool and stable. We’re sure [Paul] will be getting some great contacts on this rig. If you’re suffering from low power yourself, consider an amplifer build. Video after the break.

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The $50 Ham: Going Mobile

So far in this series, everything we’ve covered has been geared around the cheapest and easiest possible means of getting on the air: getting your Technician license, buying your first low-end portable transceiver, and checking in on the local repeater nets. That’s all good stuff, and chances are you can actually take all three of those steps and still have change left over from your $50 bill. Like I said, amateur radio doesn’t have to be expensive to be fun.

But at some point, every new ham is going to yearn for that first “real” rig, something with a little more oomph in terms of power, and perhaps with a few more features. For many Technicians, the obvious choice is a mobile rig, something that can be used to chat with fellow hams on the way to work, or to pass the time while on long road trips. Whatever your motivation is, once you buy a radio, you have to install it, and therein lie challenges galore, both electrical and mechanical.

I recently took the plunge on a mobile rig, and while the radio and antenna were an order of magnitude more expensive than $50, the process of installing it was pretty cheap. But it’s not the price of the thing that’s important in this series; rather, it’s to show that ham radio is all about doing it yourself, even when that means tearing your car apart from the inside out and rebuilding it around a radio.

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Intercontinental Radio Communications With The Help Of Fly Fishing Reels

All of us have experience in trying to explain to a confused store assistant exactly what type of kitchen implement you’re looking for, and why it is a perfectly suitable part for your autonomous flying lawn mower. Or in the case of [MM0OPX] trying to find fly fishing reels that are suitable for his  Adjustiwave multi-band VHF-HF  ham radio antenna.

HF radios allow intercontinental communication but require very large antennas which can be tricky to tune properly, and this antenna helps ease both these problems. The basic configuration is quarter wave, linear loaded (folded), vertical antenna. A quarter wave length radiator wire runs up a fibreglass pole, folds over the top, and comes back down, to form a shorter, more practical antenna while remaining the required length. Ground plane radial wires are usually added to improve performance by helping to reflect signals into antenna.

[MM0OPX] expanded this concept by using two pairs of fly fishing reels to quickly adjust the length of the radiators and radials. One reel holds the actual antenna wire while the second holds fishing braid, which is tied to the end of the wire to provided tension. The radials wire is exactly the same, it just runs across the ground.

The four reels are mounted to a plastic junction box, which houses the feed line connector and matching transformer, which is attached to the base of a fibreglass pole with hydraulic pipe clamps. Each wire is marked with heat shrink at defined points to allow quick tuning for the different frequencies. [MM0OPX] tried a couple of wire types and found that 1 mm stainless steel cable worked best.

This being Hackaday, we are big fans of repurposing things, especially when the end product is greater than the sum of its parts, as is the case here. Check out the walk around and build discussion videos after the break. Continue reading “Intercontinental Radio Communications With The Help Of Fly Fishing Reels”