Lesson 21
Power Supplies and Voltage Regulators If you have an electric circuit, you need electric power to run it. Power supplies come in many forms, from a battery, to a solar panel, to “mains” power in your home. For an amateur radio HF or Mobile rig, many are expecting a 13.8 volt DC power source. One […]
Lesson 20
Amplifiers Most of the modulator and oscillator circuits you’ll use in amateur radio put out a fairly small amount of wattage. It’s the job of the RF amplifier circuits to increase the signal strength of your output. In some cases, you’ll also find pre-amplifiers for increasing gain in your received signal. There are also voltage […]
Lesson 22
Waveforms and Measurements A waveform is a graphic representation of a signal over time. The signal that shows on an oscilloscope can be a simple sine wave. It can also be more complex forms like a square, sawtooth or triangle. A sine wave is not pure, especially when modulated. For instance, the voltage may fluctuate […]
Lesson 23
Modulation Index and Deviation Ratio Modulation is the term for varying a waveform to carry a signal, that’s why AM is named Amplitude Modulation. By the same token FM is Frequency Modulation and PM is Phase Modulation. We’re coming around to two questions in a row that people struggle with on our practice tests. It’s […]
Lesson 24
Digital Communication Modes Why use digital communication modes? A significant benefit is their efficient use of bandwidth. Let’s do a comparison of some digital modes. Bandwidth by mode Mode Transmission Parameters Bandwidth (hertz / kilohertz) Morse Code 13 Words Per Minute 52 / 0.052 FSK via FM 9600-Baud ASCII, 4800 Hertz Frequency Shift 15,360 […]
Lesson 25
Antenna Types This lesson begins a series of 5 lessons related to antennas and feedline. It’s a good area to understand to maximize performance. The right antenna and feedline set-up can have a large impact on your ham radio enjoyment. Maybe even more than your choice of a transceiver. We’ll start by looking at some […]
Lesson 26
Direction Finding Sometimes you need to locate the source of a signal. It could be because you’re doing something fun like a “fox hunt.” Or you may be trying to find where harmful interference is coming from. Either way you would use direction finding to search for the source of a signal. An effective method […]
Lesson 27
Basic Antenna Parameters How would some of those antennas perform in your back yard or other environment? It would be really helpful to know that before you start running cables and shooting lines. This lesson will help you analyze key antenna performance parameters. Antenna bandwidth is the frequency range of a given antenna. In the […]
Lesson 29
Effective Radiated Power In an earlier lesson we discussed “link margin.” It was where you calculate the additions and losses to signal in your antenna network. Another way to look at that is a term called effective radiated power. This is a view of the full station output, taking into account all gains and losses. […]
Lesson 15
Digital Integrated Circuits Integrated circuits are typically called IC’s. In radios you will find two different types of IC’s, analog and digital. Analog IC’s are used for RF things like op-amps and oscillators. This lesson will focus on those in more detail shortly. Digital IC’s are things like microprocessors. These are computers on a chip. […]
