Radio Hacks

1335 Articles

Umbrella Antenna Protects You From Rain, But Not The Way You Think

November 16, 2023 by 8 Comments

You never know when you’ll be called upon to [MacGyver] your way out of an emergency. We can’t imagine what kind of situation would call for whipping up a satellite ground station for NOAA weather satellites from junk, but hey, it could happen.

And when it does, you’ll be ready — as long as you have an umbrella, some foil tape, and various bits and bobs like wire and an RTL-SDR dongle. That’s what [saveitforparts] used for his field-expedient build, at least in the first instance; as you can imagine, builds like this take a lot of tweaking to get right. The umbrella and foil tape form the main reflector for the antenna, with a pie tin, a scrap of wire, and some random twigs being used to build the antenna’s helical feed. Attached to a SAWbird LNA/filter and an RTL-SDR plugged into a dodgy second-hand phone, he was able to get at least some kind of data from one of the GOES satellites, but it wasn’t great.

Switching the feed to a commercially available log periodic antenna worked much better, with some partial decodes of weather map data. Actually, getting anything at all with a setup like this is impressive enough for us to call it a win. It shows that the umbrella approach to antennas is valid; but then again, we already knew that.

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A Small-Packing Antenna For 2 Metre Portable Work

November 12, 2023 by 15 Comments

One of amateur radio’s many interests comes in portable operation, taking your radio to an out of the way place, usually a summit, and working the world using only what can be carried in. Often this means using the HF or shortwave bands, but the higher frequencies get a look-in as well. A smaller antenna is no less the challenge when it comes to designing one that can be carried though, and [Thomas Witherspoon] demonstrates this with a foldable loop antenna for the 2 metre band.

The antenna provides a reminder that the higher bands are nothing to be scared of in construction terms, it uses a BNC-to-4 mm socket adapter as its feedpoint, and makes the rectangular shape of the loop with pieces of fiberglass tube. The wire itself is flexible antenna wire, though we’re guessing almost any conductor could be used. The result is a basic but useful antenna that certainly packs down to a very small size, and we can see it would be a useful addition to any portable operator’s arsenal.

If you’re a 2 metre band user, this certainly isn’t the first time we’ve visited lightweight antennas for this band.

A Classic Shortwave Radio Restored

November 12, 2023 by 20 Comments

Before the Internet, if you wanted to hear news from around the world, you probably bought a shortwave receiver. In the golden age of world band radio, there was a great deal of high-quality programming on the shortwave bands and a large variety of consumer radios with shortwave bands. For example, the Sony CRF-160 that [M Caldeira] is restoring dates from the late 1960s or early 1970s and would have been a cool radio in its day. It retailed for about $250 in 1972, which sounds reasonable, but — don’t forget — in 1972 that would have been a 10% downpayment on a new car or enough to buy a Big Mac every day for a year with change left over.

As you can see in the video below, the radio seemed to work well right out of the gate, but the radio needed some rust removal and other sprucing up. However, it is an excellent teardown, with some tips about general restoration.

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Ham Radio Memes In The 1970s

November 11, 2023 by 12 Comments

If you have a fondness for old and unusual ham gear, [Saveitforparts] has a great video (see below) about a Robot slow scan receiver he found at a junk store.  Slow scan or SSTV is a way to send pictures via low-bandwidth audio, such as you often find on the ham bands. The idea is you take a picture, send some squeaks and blips over the air, and in about 8 or 10 seconds, a single frame of video shows up at the receiver. Hams aren’t the only ones who used it. The Apollo missions used an SSTV system in some cases, too.

I’ve been a ham radio operator for a very long time. When I first heard about SSTV, I thought it sounded cool that you could be talking to someone and then show them a picture of your station or your dog or your kids. But when I looked into it, the reality was far different. In the pre-internet days, SSTV-equipped hams hung out on a handful of watering hole frequencies and basically just sent memes and selfies to each other. Everyone would take turns, but there wasn’t really any conversation.

This actually still goes on, but the hardware isn’t a big deal anymore. The Robot in the video had to decode the signal from audio and store the image somehow. On old gear — some of it homebrew — it was simply persistent phosphor that would eventually fade, but, of course, eventually, images were stored in some form of digital memory. These days, you are likely to use a PC soundcard to both send and receive the necessary audio.

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Hands On With Boondock Echo

November 10, 2023 by 23 Comments

Perhaps no words fill me with more dread than, “I hear there’s something going around.” In my experience, you hear this when some nasty bug has worked its way into the community and people start getting whatever it is. I’m always on my guard when I hear about something like this, especially when it’s something really unpleasant like norovirus. Forewarned is forearmed, after all.

Since I work from home and rarely get out, one of the principal ways I keep apprised of what’s going on with public health in my community is by listening to my scanner radio. I have the local fire rescue frequencies programmed in, and if “there’s something going around,” I usually find out about it there first; after a half-dozen or so calls for people complaining of nausea and vomiting, you get the idea it’s best to hunker down for a while.

I manage to stay reasonably well-informed in this way, but it’s not like I can listen to my scanner every minute of the day. That’s why I was really excited when my friend Mark Hughes started a project he called Boondock Echo, which aims to change the two-way radio communications user experience by enabling internet-backed recording and playback. It sounded like the perfect system for me — something that would let my scanner work for me, instead of the other way around. And so when Mark asked me to participate in the beta test, I jumped at the chance.

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Machine Teaches Morse Code

November 3, 2023 by 4 Comments

If you are a ham radio operator of a certain age, you probably remember ads for “The Instructograph,” a mechanical device for learning Morse code. [Our Own Devices] has an ancient specimen of the machine and shows us how it works in the video below. The machine is a model of simplicity. You wind up a spring-driven motor like you would for an old record player or music box. A slider sets the playback rate, and paper tape starts to spin.

The paper tape looks like computer tape, but since it only has literal long and short notches, it has two distinct sides. When you learned one set of messages, you could flip the tape over and get more practice that way. How did the machine read the paper tape? With a mechanical contact. Literally, if the paper had a hole in it, you made the circuit. If it didn’t, the circuit was broken. A buzzer and batteries or some other kind of sounder was all you needed.

The company was in business for 50 years. The newer versions had more electronics, but they always used the paper tape mechanism to store the code practice sessions. A 1962 ad noted that the machine could play back the tapes from three words a minute up to 40. You could buy or rent the machine, and we always assumed it was pretty pricey for its day. Around 1965, a new unit would cost $53 but did not include a headset or a key. So that was actually more reasonable than we expected. In 1965, a brand-name clock radio cost about $50, so it wasn’t any more than that.

Everyone has their own favorite method for learning code, especially [Ludwig Koch]. At least you don’t have to learn Alex-style.

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Pocketable Yagi Antenna Really Shoots For Distance

November 2, 2023 by 45 Comments

For amateur radio operators, the quest for the perfect antenna never seems to end. Perhaps that’s because our requirements are always changing. We never quite seem to get to one design that can do everything. This copper-foil Yagi antenna might not do everything, but it really seems to tick off the boxes for gain and directionality along with ultra-portability.

If you’ve been following [Ben Eadie (VE6SFX)]’s trip down the rabbit hole of lightweight antenna building, you’ll recall that he’s already knocked off a J-pole antenna and a stealthy mobile slot antenna using little more than copper foil tape. Both of those designs performed great, but [Ben] had bigger fish to fry: he wanted to build a directional antenna for the 2-meter band and go for distance. The traditional Yagi-Uda is generally the preferred design for beam antennas, but they tend to be bulky and cumbersome. But with a roll of copper foil tape [Ben] was able to lay out a three-element Yagi on a sheet of Tyvek wrap. Reinforced with some packing tape and stiffened with a couple of fiberglass rods attached to a 3D printed handle, and it was ready to go.

[Ben]’s field test results were most impressive. Not only was he able to open up repeaters up to 90 km away, but he was getting good signal reports to boot. He was even able to reach a repeater 150 km distant, just barely though. Still, that’s mighty impressive performance from something that looks like a Union Jack and rolls up to fit in a pocket.

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