Master the Radio Arts
When it comes to oscillators, one technology that has greatly risen in popularity these past few years is DDS – Direct Digital Synthesis. An increasing number of ham projects are using DDS chips, and it is possible to find RF-capable chips at relatively affordably prices. With easy-to-use micro-controller development boards such as the Arduino, using … Read more
The Phase-Locked Loop (PLL) is one the most popular building blocks of any RF system. Understanding the PLL unlocks many possibilities for the experimenter, however many hobbyists and those relatively new to electronics are put off by its apparent complexity. While PLLs can seem daunting, by understanding the main principle behind PLL theory and dissecting … Read more
Introduction No component is as connected to ham radio history than the quartz crystal. Still today, thanks to their excellent frequency stability and cost-effectiveness, crystal oscillators in one form or another dominate the electronic landscape. You’ll find them in nearly every electronic device you can think of, from PC motherboards to your wristwatch. And, of … Read more
While it is true that at first glance oscillator circuits can seem complicated, in truth, despite the hundreds of different oscillator designs available, they are all derived from just a few possible architectures. Knowing the fundamental theory and architecture behind oscillator circuits will allow you to make sense of most oscillator designs, and also allow you to design your own.
In the previous post we went over passive LC filter design. LC filters do have many advantages: they are simple to understand and design and they don’t require an external power supply. They also are the only solution for higher frequencies. That said, they cannot provide gain. Instead, some power is lost when the signal goes…
The math behind filter design is actually very complex, and the equations that determine component values are complicated. Fortunately, most of that complexity will be transparent to you! Good news, you’ll never have to work from scratch when designing filters. Instead, filter design relies on using tables of normalized values, then extrapolating these values…
For a given cut-off frequency and filter order, there are multiple solutions for component values. Depending on these values, different responses can be created. Two filters with the same component arrangement, the same cut-off frequency, and the same order, can have different component values and different Bode plots. The most common filter families are the…
Filters are an important building block you will find in nearly all fields of electronics. They are of particular interest to the ham radio experimenter and RF designer. Out of all the building blocks of radio electronics, filters are perhaps the most simple to understand. Simple doesn’t mean unimportant however, as filters are a necessary…
Up until now we have only studied and used discrete components for amplifiers. Up until the advent of Integrated Circuits, or ICs, building your amplifier out of individual discrete thru-hole components, such as transistors, resistors, and capacitors, was the only way. While amazing things were (and still are today!) created with discrete technology, discrete active
So far, everything we’ve learned about negative feedback seems to indicate that it is a great tool with little drawbacks. The only inconvenience we’ve actually talked about was a reduction in gain. Choosing a device, or a cascade of devices, that provide a big enough gain to start with solves this problem.Unfortunately, negative feedback has…