Collaborate Disseminate
When is the speed of light not the speed of light? Of course, that’s a trick question. The speed of light may be constant, but just as sound travels at …read more Continue reading Measuring An Unknown Velocity Factor
In the realm of test equipment, there are a number of items that you don’t know you need until you need one. That’s probably the case with the HP11720A pulse …read more Continue reading A Tale of Two Pulse Modulators
Most ham radio operators will build an antenna of some sort when they first start listening or transmitting, whether it’s a simple dipole, a beam antenna like a Yagi, or …read more Continue reading Don’t Let The Baluns Float Over Your Head
Yagi-Uda antennas, or simply “Yagis”, are directional antennas that focus radio waves to increase gain, meaning that the radio waves can travel further in that direction for a given transmitter …read more Continue reading Printing Antennas on Circuit Boards
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 …read more Continue reading Homebrew Wattmeter Pays Homage to Sturdy Original
At DC and low frequency, we can pretend wires are perfect conductors. At radio frequencies, though, there are many effects that you need to take into account for wires and cables. One of these is characteristic impedance. If you have a marked cable, you can look it up on the …read more
Radio may be dead in terms of delivering entertainment, but it’s times like these when the original social network comes into its own. Being able to tune in stations from across the planet to get fresh perspectives on a global event can even be a life saver. You’ll need a …read more
Continue reading Homebrew Loop Antenna Brings the Shortwave World to You
You can say one thing for [Derek]’s amateur radio ambitions — he certainly jumps in with both feet. While most hams never even attempt to “shoot the Moon”, he’s building out an Earth-Moon-Earth, or EME, setup which requires this little beauty: a homebrew quarter-wave hardline RF divider, and he’s sharing …read more
Continue reading Shoot the Moon with this Homebrew Hardline RF Divider
We once saw an interview test for C programmers that showed a structure with a few integer, floating point, and pointer fields. The question: How big is this structure? The correct answer was either “It depends,” or “sizeof(struct x).” The same could be said of the question “What is the …read more
[Mare] has a visual guide and simple instructions for making DIY mini helical 868 MHz antennas for LoRa applications. 868 MHz is a license-free band in Europe, and this method yields a perfectly serviceable antenna that’s useful where space is constrained.
The process is simple and well-documented, but as usual with antenna design it requires attention to detail. Wire for the antenna is silver-plated copper, salvaged from the core of RG214U coaxial cable. After straightening, the wire is wound tightly around a 5 mm core. 7 turns are each carefully spaced 2 mm apart. After that, it’s just a matter …read more
Continue reading DIY Mini Helical Antennas From Salvaged Co-ax Cable