For audiophiles, musicians, and ham radio operators, the soft glow of the vacuum tube filament is not only an indication of function, but a nostalgic trigger for memories of simpler times. Though they may have been outpaced by tiny transistors and integrated circuits, these workhorses still may have something to offer in many modern devices.
For low frequency control, switching, and DC power, it is possible to get the job done without worrying too much about wiring and cabling practices. However, when RF gremlins begin to appear, suddenly, a whole new set of cautions and constraints gets piled on to your “simple” project. This article provides an overview of shielding, including some practices you should know as a defense against these gremlins.
Any conductor carrying an AC current can be treated as a transmission line. Here, we'll talk about a basic element of transmission lines: the standing wave ratio. Find out why it’s important and how to measure it.
The phenomenon known as RF interference — RFI to its many friends and acquaintances — involves interference caused by signals propagated wirelessly as radio waves. Most people don’t know (or care) about RFI until their garage door opener won’t work.
Rings, beads, cores ... find out exactly what ferrite is and what makes it ideal for a variety of uses in electronics. First created in 1930, they have since become important materials in the electronics and RF world.
Listening to shortwave radio is very interesting, and filled with the voices and music of far-off lands. Digging a bit deeper, there is another world of shortwave radio that does not use conventional sounds. It is the realm of data transmissions.
Every signal begins with an oscillator — In ham radio, the oscillator is a key element in generating signals, mixing them together, and extracting the information from them. Let's see how to make an audio oscillator, plus learn about common RF types.
Previously, we learned what makes an oscillator do what it does, and tried a simple low frequency example. Now, it's time to move up — in frequency — to the oscillators which make the signals that drive the ham's wireless world.
The Smith Chart is one of the most useful tools in radio communications, but it is often misunderstood. After reading this introduction to the basics, you will have a better understanding of impedance matching and VSWR — common parameters in a radio station.
