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Hackaday Links: October 3, 2021

It’s one thing to speculate about what’s happening with the Mars helicopter Ingenuity, but it’s another to get an insider’s view on recent flight problems. As we previously reported, Ingenuity is starting to face a significant challenge, as a seasonal atmospheric pressure drop on Mars threatens to make the already rarefied air too thin to generate useful lift. Mission controllers tested the chopper at higher rotor speeds, and while that worked, later attempts to fly using that higher speed resulted in an abort. The article, written by one of the NASA/JPL engineers, is a deep dive into the problem, which occurred when Ingenuity sensed excessive wiggle in two of the servos controlling the rotor swashplate. The thought is that accumulated wear in the servos and linkages might be causing the problem; after all, Ingenuity has made thirteen flights so far, greatly exceeding the five flights originally programmed for it. Here’s hoping they can adapt and keep the helicopter flying, but whatever they do, it’ll have to wait a few weeks until Mars completes its conjunction and pops back out from behind the Sun.

With all the attention understandably paid to the recent 20th anniversary of the 9/11 terror attacks, it’s easy to forget that barely a month after that day, a series of what appeared to be follow-on attacks started: the Anthrax Attacks. Members of Congress and media outlets were targeted via the mail with highly refined anthrax spores, leading to the deaths of five people, with dozens more injured and exposed to anthrax. IEEE Spectrum has an interesting article that goes into some of the technology that was rapidly deployed in an attempt to sanitize the mail, including electron beam and X-ray irradiation to kill any spores. The article also points out how this wasn’t the first time people were afraid of the mail; outbreaks of yellow fever in 1899 led to fumigation of the mail with sulfur, after perforating it with a wicked-looking paddle.

Attention PCB-design newbies — now’s your chance to learn the entire PCB design process from the ground up, with the guidance of industry professionals. TeachMePCB is back again this year, offering to teach you everything you need to know about properly laying out a PCB design in pretty much any EDA software you want. The course requires a two- to five-hour commitment every week for two months, after which you’ll have designed a PCB for a macropad using a Raspberry Pi Pico. The course facilitator is Mark Hughes from Royal Circuits, who did a great Hack Chat with us last year on PCB finishes. This seems like a great way to get up to speed on PCB design, so if you’re interested, act soon — 460 people are already signed up, and the deadline is October 10.

Some of us really love factory tours, no matter what the factory is making. All the better when the factory makes cool electronics stuff, and better still when it’s our friends at Adafruit showing us around their New York City digs. True, it’s a virtual tour, but it has pretty much become a virtual world over the last couple of years, and it’s still a great look inside the Adafruit factory. Hackaday got an in-person tour back in 2015, but we didn’t know their building used to be a Westinghouse radio factory. In fact, the whole area was once part of the famed “Radio Row” that every major city seemed to have from the 1920s to the 1960s. It’s good to get a look inside a real manufacturing operation, especially one that’s right in the heart of a city.

And finally, those with a fear of heights might want to avoid watching this fascinating film on the change-out of a TV transmitter antenna. The tower is over 1,500′ (450 m) tall, lofting an aging antenna over the flat Florida terrain. Most of the footage comes from body-mounted cameras on the riggers working the job, including the one very brave soul who climbed up the partially unbolted antenna to connect it to the Sikorsky S64 Skycrane helicopter. It’s a strange combination of a carefully planned and slowly executed ballet, punctuated by moments of frenetic activity and sheer terror. The mishap when releasing the load line after the new antenna was placed could easily have swept the whole rigging crew off the antenna, but luckily nobody was injured.

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A Bird 43 wattmeter and its homebrew equivalent

Homebrew Wattmeter Pays Homage To Sturdy Original

If there’s one instrument that hams and other radio enthusiasts covet, it’s the venerable Bird 43 Thruline wattmeter. The useful RF tool has barely changed in the nearly 70 years since it was first introduced, and they’re built like a tank. This makes Bird meters highly desirable, and therefore quite expensive either brand new or on the swap-meet circuit.

But radio amateurs are nothing if not resourceful, and building a homebrew version of the Bird wattmeter (in Portuguese; Google translate tool at the bottom of the page) as Brazilian ham [Luciano Sturaro (PY2BBS)] did is a good way to get your hands on one. Granted, [Luciano] had a head start: a spare line set, which is the important bit from a Bird wattmeter. The machined metal part is in effect an air-insulated section of coaxial cable that the RF signal passes through on its way from transmitter to antenna. A “slug” is inserted into the cavity in the line set to sense the RF and couple it to the meter electronics; the slug can be rotated to measure RF traveling in either direction, allowing the user to determine how much RF is getting reflected by the antenna system.

[Luciano]’s version of the meter is faithful to the sturdy construction of the original, with a solid steel case that mimics its classic lines — the case even sports the same color scheme and stout leather carry handle. There are some changes to the electronics, and the meter movement itself is different from the original, but all in all, the “Buzz 50” looks fantastic. We especially love the detailed nameplate as an homage to Bird.

The thing about Bird — and Bird-like — meters is that the slugs are like potato chips; you can’t have just one. Curious as to how these slugs work? Check out this slug repair project.

[Featured image of Bird 43 Wattmeter: Martin RF Supply]

Thanks to [Niko Huenk] for the tip!

A 3-6-9 Antenna Pulls In The Signals

Every time we see a dispatch from [Mr. Carlson], we imagine it is being beamed from his orbital station packed full of vintage radio gear. We are certain the reality is more terrestrial, but if we were going to build an orbiting lab, it might look like [Carlson’s] shack. In his latest communique, he shares his progress working on a high-performance 3-6-9 receiving antenna design and you can see it in the video below.

Although the antenna isn’t done, it is already working and looks impressive. There’s a lot of wire, so this probably isn’t a condo-friendly solution. The name of the antenna derives from the three wires, one tuned for 3 MHz, one for 6 MHz, and the other for 9 MHz.

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Hackaday Links: September 12, 2021

The last thing an astronaut or cosmonaut on the International Space Stations wants to hear from one of their crewmates is, “Do you smell plastic burning?” But that’s apparently what happened this week aboard the increasingly problematic spacecraft, as the burning smell and visible smoke spread from the Russian Zvezda module to the American side of town. The reports say it occurred while charging the station’s batteries, and we all know how dicey that can get. But apparently, the situation resolved itself somehow, as normal operations continued soon after the event. Between reports of cracks, air leaks, problems with attitude control, and even accusations of sabotage, the ISS is really starting to show its age.

Speaking of burning and batteries, normally a story about burning Tesla batteries wouldn’t raise our eyebrows much. But this story out of California introduces a potential failure mode for Tesla batteries that we hadn’t considered before. It seems a semi-truck with a load of Tesla batteries lost its brakes on Interstate 80 in the Sierra Nevada mountains and ended up flipping across the highway. Video from the scene shows the cargo, which looks like replacement batteries or perhaps batteries salvaged from wrecked cars, scattered across the highway on their shipping pallets. A fire was reported, but it’s not clear whether it was one of the batteries which had gotten compromised in the crash, or if it was something other than the batteries. Still, we hadn’t considered the potential for disaster while shipping batteries like that.

Attention all GNURadio fans — GRCon21 is rapidly approaching. Unlike most of the conferences over the last year and half, GRCon21 will actually be both live and online. We always love the post-conference dump of talks, which cover such a wide range of topics and really dive deeply into so many cool areas. We’re especially looking forward to the SETI talks, and we’re pleased to see our friend Hash, who was on the Hack Chat a while back, scheduled to talk about his smart-meter hacking efforts. The conference starts on September 20 and is being held in Charlotte, North Carolina, and virtually of course. If you attend, make sure to drop tips to your favorite talks in the tips line so we can share them with everyone.

We got a tip this week on a video about how 1/4-wave tuning stubs work. It’s a simple demonstration using a length of coax, a signal generator, and an oscilloscope to show how an unterminated feedline can reflect RF back to the transmitter, and how that can be used to build super-simple notch filters and impedance transformers. We love demos that make the mysteries of RF a little simpler — W2AEW’s videos come to mind, like this one on standing waves.

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Improving Cheap SDR Antennas

[VK3YE] knows there are at least two things wrong with the cheap antennas you get with most SDR dongles. First, they are too short. You’d like to have enough to pull out a quarter wavelength on the longest frequency you want to operate. The second problem is there’s no real ground. He fixed both of these problems, as you can see in the video below.

The result might be called an ugly duckling rather than a rubber ducky. But it does seem to work. You could probably come up with something nicer to reseal the base, but the tape does work. A nice 3D printed housing would work, too, and might improve the appearance. We also thought about the goop you use on tool handles.

We actually have simply cut these antennas off and reused the cable and connector to hook up a better antenna. You might get more mileage out of that approach. On the other hand, the magnetic base and reasonably small form factor is pretty attractive.

If you want to do before and after testing, we’d suggest using Python. Or, just bite the bullet and build something that looks like it belongs in a movie.

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A Cheap Dipole Antenna From An Extension Cord

Dipoles are a classic builder’s antenna, after all they are usually little more than two pieces of wire and a feedline. But as [Rob] shows us in the video below, there are a few things to consider.

The first thing is where to get the wire. A damaged extension cord donated the wire. That’s actually an interesting idea because you get multiple wires the same length inside the extension cord.  Continue reading “A Cheap Dipole Antenna From An Extension Cord”

New Video Series: Learning Antenna Basics With Karen Rucker

We don’t normally embrace the supernatural here at Hackaday, but when the topic turns to the radio frequency world, Arthur C. Clarke’s maxim about sufficiently advanced technology being akin to magic pretty much works for us. In the RF realm, the rules of electricity, at least the basic ones, don’t seem to apply, or if they do apply, it’s often with a, “Yeah, but…” caveat that’s sometimes hard to get one’s head around.

Perhaps nowhere does the RF world seem more magical than in antenna design. Sure, an antenna can be as simple as a straight piece or two of wire, but even in their simplest embodiments, antennas belie a complexity that can really be daunting to newbie and vet alike. That’s why we were happy to recently host Karen Rucker’s Introduction to Antenna Basics course as part of Hackaday U.

The class was held over a five-week period starting back in May, and we’ve just posted the edited videos for everyone to enjoy. The class is lead by Karen Rucker, an RF engineer specializing in antenna designs for spacecraft who clearly knows her business. I’ve watched the first video of the series and so far and really enjoy Karen’s style and the material she has chosen to highlight; just the bit about antenna polarization and why circular polarization makes sense for space communications was really useful. I’m keen to dig into the rest of the series playlist soon.

The 2021 session of Hackaday U may be wrapped up now, but fear not — there’s plenty of material available to look over and learn from. Head over to the course list on Hackaday.io, pick something that strikes your fancy, and let the learning begin!

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