radio

569 Articles

Going Ham Mobile On A Bicycle

July 8, 2024 by 19 Comments

It’s said that “Golf is a good walk spoiled,” so is attaching an amateur radio to a bike a formula for spoiling a nice ride?

Not according to [Wesley Pidhaychuk (VA5MUD)], a Canadian ham who tricked out his bike with a transceiver and all the accessories needed to work the HF bands while peddling along. The radio is a Yaesu FT-891, a workhorse mobile rig covering everything from the 160-meter band to 6 meters. [Wes] used some specialized brackets to mount the radio’s remote control head to the handlebars, along with an iPad for logging and a phone holder for streaming. The radio plus a LiFePO4 battery live in a bag on the parcel rack in back. The antenna is a Ham Stick mounted to a mirror bracket attached to the parcel rack; we’d have thought the relatively small bike frame would make a poor counterpoise for the antenna, but it seems to work fine — well enough for [Wes] to work some pretty long contacts while pedaling around Saskatoon, including hams in California and Iowa.

The prize contact, though, was with [WA7FLY], another mobile operator whose ride is even more unique: a 737 flying over Yuma, Arizona. We always knew commercial jets have HF rigs, but it never occurred to us that a pilot who’s also a ham might while away the autopilot hours working the bands from 30,000 feet. It makes sense, though; after all, if truckers do it, why not pilots?

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Hackaday Links: July 7, 2024

July 7, 2024 by 7 Comments

Begun, the Spectrum Wars have. First, it was AM radio getting the shaft (last item) and being yanked out of cars for the supposed impossibility of peaceful coexistence with rolling broadband EMI generators EVs. That battle has gone back and forth for the last year or two here in the US, with lawmakers even getting involved at one point (first item) by threatening legislation to make terrestrial AM radio available in every car sold. We’re honestly not sure where it stands now in the US, but now the Swiss seem to be entering the fray a little up the dial by turning off all their analog FM broadcasts at the end of the year. This doesn’t seem to be related to interference — after all, no static at all — but more from the standpoint of reclaiming spectrum that’s no longer turning a profit. There are apparently very few analog FM receivers in use in Switzerland anymore, with everyone having switched to DAB+ or streaming to get their music fix, and keeping FM transmitters on the air isn’t cheap, so the numbers are just stacked against the analog stations. It’s hard to say if this is a portent of things to come in other parts of the world, but it certainly doesn’t bode well for the overall health of terrestrial broadcasting. “First they came for AM radio, and I did nothing because I’m not old enough to listen to AM radio. But then they came for analog FM radio, and when I lost my album-oriented classic rock station, I realized that I’m actually old enough for AM.”

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Hacking A Quansheng Handheld To Transmit Digital Modes

July 5, 2024 by 12 Comments

Have you ever thought about getting into digital modes on the ham bands? As it turns out, you can get involved using the affordable and popular Quansheng UV-K6 — if you’re game to modify it, that is. It’s perfectly achievable using the custom Mobilinkd firmware, the brainchild of one [Rob Riggs].

In order to efficiently transmit digital modes, it’s necessary to make some hardware changes as well. Low frequencies must be allowed to pass in through the MIC input, and to pass out through the audio output. These are normally filtered out for efficient transmission of speech, but these filters mess up digital transmissions something fierce.  This is achieved by messing about with some capacitors and bodge wires. Then, one can flash the firmware using a programming cable.

With the mods achieved, the UV-K6 can be used for transmitting in various digital modes, like M17 4-FSK. The firmware has several benefits, not least of which is cutting turnaround time. This is the time the radio takes to switch between transmitting and receiving, and slashing it is a big boost for achieving efficient digital communication. While the stock firmware has an excruciating slow turnaround of 378 ms, the Mobilinkd firmware takes just 79 ms.

Further gains may be possible in future, too. Bypassing the audio amplifier could be particularly fruitful, as it’s largely in the way of the digital signal stream.

Quansheng’s radios are popular targets for modification, and are well documented at this point.

So Much Going On In So Few Components: Dissecting A Microwave Radar Module

July 1, 2024 by 17 Comments

In the days before integrated circuits became ubiquitous, providing advanced functionality in a single package, designers became adept at extracting the maximum use from discrete components. They’d use clever circuits in which a transistor or other active part would fulfill multiple roles at once, and often such circuits would need more than a little know-how to get working. It’s not often in 2024 that we encounter this style of circuit, but here’s [Maurycy] with a cheap microwave radar module doing just that.

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Learning Morse Code With A DIY Trainer

June 22, 2024 by 18 Comments

Morse code, often referred to as continuous wave (CW) in radio circles, has been gradually falling out of use for a long time now. At least in the United States, ham radio licensees don’t have to learn it anymore, and the US Coast Guard stopped using it even for emergencies in 1999. It does have few niche use cases, though, as it requires an extremely narrow bandwidth and a low amount of power to get a signal out and a human operator can usually distinguish it even if the signal is very close to the noise floor. So if you want to try and learn it, you might want to try something like this Morse trainer from [mircemk].

While learning CW can be quite tedious, as [mircemk] puts it, it’s actually fairly easy for a computer to understand and translate so not a lot of specialized equipment is needed. This build is based around the Arduino Nano which is more than up for the job. It can accept input from any audio source, allowing it to translate radio transmissions in real time, and can also be connected to a paddle or key to be used as a trainer for learning the code. It’s also able to count the words-per-minute rate of whatever it hears and display it on a small LCD at the front of the unit which also handles displaying the translations of the Morse code.

If you need a trainer that’s more compact for on-the-go CW, though, take a look at this wearable Morse code device based on the M5StickC Plus instead.

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Hackaday Links: June 9, 2024

June 9, 2024 by 32 Comments

We’ve been harping a lot lately about the effort by carmakers to kill off AM radio, ostensibly because making EVs that don’t emit enough electromagnetic interference to swamp broadcast signals is a practical impossibility. In the US, push-back from lawmakers — no doubt spurred by radio industry lobbyists — has put the brakes on the move a bit, on the understandable grounds that an entire emergency communication system largely centered around AM radio has been in place for the last seven decades or so. Not so in Japan, though, as thirteen of the nation’s 47 broadcasters have voluntarily shut down their AM transmitters in what’s billed as an “impact study” by the Ministry of Internal Affairs and Communications. The request for the study actually came from the broadcasters, with one being quoted in a hearing on the matter as “hop[ing] that AM broadcasting will be promptly discontinued.” So the writing is apparently on the wall for AM radio in Japan.

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Grid Leak Radio Draws The Waves

May 23, 2024 by 11 Comments

[Stephen McNamera] found a schematic for a grid leak radio online and decided to throw together a few tubes on a piece of wood and see how it worked. As you can see in the video below, it works well. The video is a bit light on details, but the web page he found the plans on also has quite a bit of explanation.

The name “grid leak detector” is due to the grid leak resistor between the grid and ground, in this case, a 2.7 megaohm resistor. The first tube does everything, including AM detection. The second tube is just an audio amplifier that drives the speaker. This demodulation method relies on the cathode to control grid conduction characteristics and was found in radios up to about the 1930s. The control grid performs the usual function but also acts as a diode with the cathode, providing demodulation. In a way, this is similar to a crystal radio but with an amplified tube diode instead of a crystal.

It looks like [Stephen] wound his own coil, and the variable capacitor looks suspiciously like it may have come from an old AM radio. The of the old screw terminal tube sockets on the wood board looks great. Breadboard indeed! What we didn’t see is where the 150 V plate voltage comes from. You hope there is a transformer somewhere and some filter capacitors. Or, perhaps he has a high-voltage supply on the bench.

While tubes are technologically passe, we still like them. Especially in old radios. Just take care around the high voltages, please.

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