Radio Hacks

1334 Articles

Hidden Gutter Antenna Keeps HOA Happy

August 27, 2024 by 140 Comments

The United States and a few other countries have an astounding array of homeowners’ associations (HOAs), local organizations that exert an inordinate influence on what homeowners can and can’t do with their properties, with enforcement mechanisms up to foreclosure. In the worst cases they can get fussy about things like the shade of brown a homeowner can paint their mailbox post, so you can imagine the problems they’d have with things like ham radio antennas. [Bob] aka [KD4BMG] has been working on tuning up his rain gutters to use as “stealth” antennas to avoid any conflicts with his HOA.

With the right antenna tuner, essentially any piece of metal can be connected to a radio and used as an antenna. There are a few things that improve that antenna’s performance, though. [Bob] already has an inconspicuous coax connector mounted on the outside of his house with an antenna tuner that normally runs his end-fed sloper antenna, which also looks like it includes a fairly robust ground wire running around his home. All of this is coincidentally located right beside a metal downspout, so all this took to start making contacts was to run a short wire from the tuner to the gutter system.

With the tuner doing a bit of work, [Bob] was able to make plenty of contacts from 10 to 80 meters, with most of the contacts in the 20 – 30 meter bands. Although the FCC in the US technically forbids HOAs from restricting reasonable antennas, if you’d rather not get on the bad side of your least favorite neighbors there are a few other projects from [Bob] to hide your gear.

Continue reading “Hidden Gutter Antenna Keeps HOA Happy” →

A Simple But Effective Receiving Loop Antenna

August 25, 2024 by 21 Comments

There’s a joke in the world of radio that all you need for a HF antenna is a piece of wet string, but the truth is that rudimentary antennas rarely perform well. Random pieces of wire may pull in some signal, but along with it comes a ton of unwanted interference and noise. It’s thus worth putting in the effort to make a better antenna, and if you’re not fortunate enough to have a lot of space, your best choice may be a magnetic loop. [Robert Hart] takes us through the design of a receive-only coaxial loop. It’s referred to as a Moebius loop because the conductor takes a “twist” path between the inner and outer halfway around.

The idea of a loop antenna is simple enough. It’s an inductor intended to respond to the magnetic portion of the wave rather than the electric part. They’re normally made of a single turn of wire in a loop of diameter well below half a wavelength, and, in their transmitting versions, they are often tuned to resonance by an air-spaced variable capacitor. Coaxial loops like this one provide enhanced resistance to electrical noise. He’s using some rather expensive Andrews coax for its rigidity, but the less well-heeled can use cheaper stuff without penalty. The result, when put on a frame of PVC pipe and a speaker stand, is an excellent portable receiving antenna, and if we’re being honest, something we might also consider in our own shack.

Continue reading “A Simple But Effective Receiving Loop Antenna” →

Pi Pico SDR On A Breadboard

August 12, 2024 by 25 Comments

How hard is it to make a fully standalone SDR? [101 Things] shows you how to take a breadboard, a PI Pico, and two unremarkable chips to create a capable radio. You can see the whole thing in the video below.

The design uses a standard Tayloe demodulator. There’s also an encoder and an OLED display for a user interface. You might also want to include some PC speakers to get a bit more audio out of the device.

Continue reading “Pi Pico SDR On A Breadboard” →

The First New Long Wave Radio Station Of This Millennium

August 11, 2024 by 34 Comments

The decline of AM broadcast radio is a slow but inexorable process over much of the world, but for regions outside America there’s another parallel story happening a few hundred kilohertz further down the spectrum. The long wave band sits around the 200kHz mark and has traditionally carried national-level programming due to its increased range. Like AM it’s in decline due to competition from FM, digital, and online services, and one by one the stations that once crowded this band are going quiet. In the middle of all this it’s a surprise then to find a new long wave station in the works in the 2020s, bucking all contemporary broadcasting trends. Arctic 252 is based in Finland with programming intended to be heard across the Arctic region and aims to start testing in September.

The hack in this is that it provides an opportunity for some low-frequency DXing, and given the arctic location, it would be extremely interesting to hear how far it reaches over the top of the world into the northern part of North America. The 252KHz frequency is shared with a station in North Africa that may hinder reception for some Europeans, but those with long memories in north-west Europe will find it fairly empty as it has been vacated in that region by the Irish transmitter which used to use it.

So if you have a receiver capable of catching long wave and you think you might be in range, give it a listen. Closer to where this article is being written, long wave stations are being turned off.

Harris & Ewing, photographer, Public domain.

Be Your Own DJ With QN8066 And An Arduino Library

August 10, 2024 by 5 Comments

The QN8066 is a fun little FM transmitter chip. It covers the full FM broadcast band and has built-in DSP. You would find this sort of part in car cell phone adapters before every vehicle included Bluetooth or an AUX port.  [Ricardo] has created an Arduino library to bring the QN8066 to the masses.

The chip is rather easy to use – control is handled with a common I2C interface. All the complex parts – Phase Locked Loop (PLL), RF front end, power management, and audio processing are all hidden inside. [Ricardo’s] library makes it even easier to use. One of the awesome features of the 8066 is the fact that it handles Radio Data System (RDS). RDS is the subcarrier datastream that allows FM stations to inject information like song title and artist into the signal. The data is then displayed on your radio screen.

You can find the source to [Ricardo’s] library on GitHub. Using it is as simple as picking it up from the Arduino IDE.

If you are looking for an RDS-enabled radio to test out your QN8066 design, you wouldn’t do too bad with this Gameboy cartridge receiver.

Click through the break for a video from [Ricardo] explaining his QN8066 design. Continue reading “Be Your Own DJ With QN8066 And An Arduino Library” →

The Waveguide Explanation You Wish You’d Had At School

August 9, 2024 by 13 Comments

Anyone who has done an electronic engineering qualification will at some point have had to get to grips with transmission lines, and then if they are really lucky, waveguides. Perhaps there should be one of those immutable Laws stating that for each step in learning about these essential parts, the level of the maths you are expected to learn goes up in an exponential curve, for it’s certainly true that most of us breathe a hefty sigh of relief when that particular course ends. It’s not impossible to understand waveguides though, and [Old Hack EE] is here to slice through the formulae with some straightforward explanations.

First of all we learn about the basics of propagation in a waveguide, then we look at the effects of dimension on frequency. Again, there’s little in the way of head-hurting maths, just real-world explanations of cutt-off frequencies, and of coupling techniques. For the first time we’ve seen, here are simple and understandable explanations of the different types of splitter, followed up by the famous Magic T. It’s all in the phase, this is exactly the stuff we wish we’d had at university.

The world needs more of this type of explanation, after all it’s rare to watch a YouTube video and gain an understanding of something once badly taught. Take a look, the video is below the break.

Continue reading “The Waveguide Explanation You Wish You’d Had At School” →

Vintage Crystal Radio Draws The Waves

August 7, 2024 by 10 Comments

The classic crystal radio was an oatmeal box with some wire and a few parts. [Michael Simpson] has something very different. He found an assembled Philmore “selective” radio kit. The simple kit had a coil, a germanium diode, and a crystal earphone.

We were sad when [Michael] accidentally burned a part of the radio’s coil. But–well–in the end, it all worked out. We’ll just say that and let you watch for yourself. The radio is simplicity itself, built on a wooden substrate with a very basic coil and capacitor tuned circuit. Continue reading “Vintage Crystal Radio Draws The Waves” →