Basic Electronics for the Amateur Radio Operator: What You Need to Know for Your Technician License

1,003 words, 5 minutes read time.

If you’re preparing for the Amateur Radio Technician License Exam, understanding basic electronics is a must. While you don’t need to be an electrical engineer, the exam includes fundamental concepts like Ohm’s Law, circuits, components, and RF safety. This guide will walk you through the essential topics, ensuring you’re ready for the test and your first steps as a ham radio operator.

Understanding Electricity: The Basics for Amateur Radio

Electricity is the movement of electrons through a conductor, like a wire. Three key electrical properties define how electricity behaves:

• Voltage (V) is the force that pushes electrons through a circuit. It’s measured in volts (V).
• Current (I) is the flow of electrons, measured in amperes (A).
• Resistance (R) opposes the flow of electricity and is measured in ohms (Ω).

These three are tied together by Ohm’s Law, a fundamental equation in electronics:

V=I×R

This means if you know any two values, you can calculate the third. Understanding this equation is critical for both the exam and real-world troubleshooting.

Direct Current (DC) vs. Alternating Current (AC)

Electricity comes in two forms:

• Direct Current (DC) flows in one direction. Batteries and solar panels produce DC.
• Alternating Current (AC) changes direction many times per second. Household electricity is AC because it’s more efficient for transmission over long distances.

For amateur radio, most equipment runs on DC power, but you’ll also need to understand AC because radio signals are alternating currents that oscillate at high frequencies.

Essential Electronic Components and Their Functions

Several key electronic components appear on the Technician Exam. Here’s what they do:

• Resistors limit current flow.
• Capacitors store and release energy, often used in filtering circuits.
• Inductors store energy in magnetic fields and are important in tuning circuits.
• Diodes allow current to flow in only one direction, useful in rectifier circuits that convert AC to DC.
• Transistors act as switches and amplifiers in radio circuits.

Understanding these basics helps you answer questions about circuit behavior and troubleshooting.

Series and Parallel Circuits

Circuits are made up of components arranged in either series or parallel:

• In a series circuit, current flows through all components one after another. The same current passes through each, but the voltage is divided.
• In a parallel circuit, components share the same voltage, but the current divides among them.

For the exam, you should know how voltage, current, and resistance behave in each type of circuit. For example, total resistance in a series circuit is the sum of all resistances, while in parallel circuits, total resistance is lower than the smallest individual resistor.

Basic AC Concepts and Frequency

Radio waves are AC signals that oscillate at different frequencies. Frequency (f) is measured in hertz (Hz) and tells us how many times per second the wave changes direction. One kilohertz (kHz) is 1,000 Hz, and one megahertz (MHz) is 1,000,000 Hz.

Ham radios operate in different frequency bands, such as:

• VHF (Very High Frequency): 30 MHz – 300 MHz (e.g., 2-meter band)
• UHF (Ultra High Frequency): 300 MHz – 3 GHz (e.g., 70-centimeter band)

Higher frequencies allow for shorter antennas and are good for local communication, while lower frequencies travel further.

Modulation: How We Send Information Over Radio Waves

Modulation is how a radio wave (carrier wave) carries information. The Technician Exam covers three main types:

• Amplitude Modulation (AM): The signal strength (amplitude) changes with the voice signal.
• Frequency Modulation (FM): The frequency of the wave changes to encode information. FM is more resistant to noise and is commonly used in VHF and UHF bands.
• Single Sideband (SSB): A variation of AM that uses less bandwidth and is more efficient for long-distance communication.

Knowing these helps when selecting modes for different types of contacts.

Power, Batteries, and Safety

Most ham radios run on 12V DC power sources, such as batteries or regulated power supplies. It’s important to understand:

• Battery safety: Overcharging or short-circuiting batteries (especially lithium-ion) can be dangerous.
• Fuse protection: Many radios have built-in fuses to prevent excessive current draw.

Another key topic on the test is RF exposure safety. High-power transmissions can generate strong radio frequency (RF) radiation, which may cause health risks. To minimize exposure:

• Maintain a safe distance from transmitting antennas.
• Use the lowest power necessary for effective communication.
• Follow FCC RF exposure limits for your frequency and power level.

Ohm’s Law in Real-World Ham Radio Applications

A common exam question might involve calculating current or voltage using Ohm’s Law. For example:

Question: If a radio operates at 12V and draws 2A of current, what is the resistance?

Using Ohm’s Law:

Understanding these calculations can help with troubleshooting and designing circuits.

Final Thoughts: Studying for the Exam and Beyond

The Technician License Exam covers these topics, but learning electronics doesn’t stop there. Once licensed, you’ll continue exploring concepts like antenna design, signal propagation, and digital communication.

Great resources for studying include:

• ARRL’s Technician Class License Manual: The official guide with explanations and practice questions.
• HamStudy.org: Free practice tests and flashcards.
• QRZ.com Practice Exams: Simulated tests with real exam questions.

By mastering these basic electronics concepts, you’ll be well on your way to passing the exam and starting your journey in amateur radio. Keep practicing, get hands-on experience, and soon, you’ll be making contacts on the air!

D. Bryan King

Sources

• American Radio Relay League (ARRL) – Official Site
• FCC Amateur Radio Service – Licensing and Regulations
• QRZ.com – Amateur Radio Callsign Database
• HamStudy.org – Exam Prep and Study Tools
• Electronics Tutorials – Basic Circuit Theory
• RadioReference.com – Frequency Database and Scanner Information
• AMSAT – Amateur Radio Satellites and Space Communications
• DX Engineering – Ham Radio Equipment and Resources
• MikroE Learn – Electronics and Circuit Design Tutorials
• Radio Society of Great Britain (RSGB) – Ham Radio Resources
• Arduino – Microcontrollers and DIY Electronics for Ham Radio
• eHam.net – Amateur Radio News, Reviews, and Forums

Disclaimer:

The views and opinions expressed in this post are solely those of the author. The information provided is based on personal research, experience, and understanding of the subject matter at the time of writing. Readers should consult relevant experts or authorities for specific guidance related to their unique situations.

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Analog Devices presented three #powerplatform solutions — advanced multiphase architecture, coupled #inductors technology and #highpower–density POLs — to address the power design challenges.

https://www.powerelectronicsnews.com/solving-power-design-challenges-in-datacenter-and-communications-applications/

Winding Your Own Small Coils

Depending on what you build, you may or may not run into a lot of inductors. If you need small value coils, it is easy to make good-looking coils, and [JohnAudioTech] shows you how. Of course, doing the winding itself isn't that hard, but you do need to know how to estimate the number of turns you need and how to validate the coil by measurement.

[John] uses a variety of techniques to estimate and measure his coils ranging from math to using an oscilloscope. He even uses an old-fashioned nomogram from a Radio Shack databook circa 1972.

In fact, we get the idea that [John] really misses Radio Shack. In addition to the book, we noted guest appearances from a Radio Shack calculator and a caliper. We were a bit surprised that he didn't use a Radio Shack pen as a coil form.

Traditionally, if you wanted to keep your coils from moving much, you'd paint them with "coil dope" or "Q dope" which doesn't interfere much with the coil's desirable characteristics. You can buy it, still, but it is also fairly easy to make by dissolving styrofoam packing peanuts.

If you need a variable inductor, you can make those, too. If, however, you are making a lot of inductors, consider automation.

#parts #coil #coils #inductor #inductors

Smaller is Sometimes Better: Why Electronic Components are So Tiny

Perhaps the second most famous law in electronics after Ohm's law is Moore's law: the number of transistors that can be made on an integrated circuit doubles every two years or so. Since the physical size of chips remains roughly the same, this implies that the individual transistors become smaller over time. We've come to expect new generations of chips with a smaller feature size to come along at a regular pace, but what exactly is the point of making things smaller? And does smaller always mean better?

Smaller Size Means Better Performance

Over the past century, electronic engineering has improved massively. In the 1920s, a state-of-the-art AM radio contained several vacuum tubes, a few enormous inductors, capacitors and resistors, several dozen meters of wire to act as an antenna, and a big bank of batteries to power the whole thing. Today, you can listen to a dozen music streaming services on a device that fits in your pocket and can do a gazillion more things. But miniaturization is not just done for ease of carrying: it is absolutely necessary to achieve the performance we've come to expect of our devices today.

A module from a 1950s IBM 700 computer. Note the enormous size of all components. Credit: autopilot, CC BY-SA 3.0

One obvious benefit of smaller components is that they allow you to pack more functionality in the same volume. This is especially important for digital circuits: more components means you can do more processing in the same amount of time. For instance, a 64-bit processor can, in theory, process eight times as much information as an 8-bit CPU running at the same clock frequency. But it also needs eight times as many components: registers, adders, buses and so on all become eight times larger. So you'd need either a chip that's eight times larger, or transistors that are eight times smaller.

The same thing holds for memory chips: make smaller transistors, and you have more storage space in the same volume. The pixels in most of today's displays are made of thin-film transistors, so here it also makes sense to scale them down and achieve a higher resolution. However, there's another, crucial reason why smaller transistors are better: their performance increases massively. But why exactly is that?

It's All About the Parasitics

A diagram illustrating the parasitic capacitances of a transistor. Credit: Michel Bakni, CC BY-SA 4.0

Whenever you make a transistor, it comes with a few additional components for free. There's resistance in series with each of the terminals. Anything that carries a current also has self-inductance. And finally, there's capacitance between any two conductors that face each other. All of these effects eat power and slow the transistor down. The parasitic capacitances are especially troublesome: they need to be charged and discharged every time the transistor switches on or off, which takes time and current from the supply.

The capacitance between two conductors is a function of their physical size: smaller dimensions mean smaller capacitances. And because smaller capacitances mean higher speed as well as lower power, smaller transistors can be run at higher clock frequencies and dissipate less heat while doing so.

Capacitance is not the only effect that changes when you scale down a transistor: lots of weird quantum-mechanical effects pop up that are not apparent for larger devices. In general however, making transistors smaller makes them faster. But there's more to electronics than just transistors. How do other components fare when you scale them down?

Not So Fast

In general, passive components like resistors, capacitors and inductors don't become much better when you make them smaller: in many ways, they become worse. Miniaturizing these components is therefore done mainly just to be able to squeeze them into a smaller volume, and thereby saving PCB space.

Resistors can be reduced in size without much penalty. The resistance of a piece of material is given by , where l is the length, A the cross-sectional area and ρ the resistivity of the material. You can simply scale down the length and cross-section and end up with a resistor that's physically smaller, but still has the same resistance. The only downside is that a physically small resistor will heat up more compared to a larger one when it dissipates the same amount of power. Therefore, small resistors can only be used in low-power circuits. The table shows how the maximum power rating of SMD resistors goes down as their dimensions are reduced.

Metric | Imperial | Power rating (W)
---|---|---
2012 | 0805 | 0.125
1608 | 0603 | 0.1
1005 | 0402 | 0.06
0603 | 0201 | 0.05
0402 | 01005 | 0.031
03015 | 009005 | 0.02
Small, smaller, smallest: tiny resistors compared to a 0.5 mm mechanical pencil lead. Credit: Rohm Semiconductor

Today, the smallest resistors you can buy are metric 03015 size (0.3 mm x 0.15 mm). With a power rating of just 20 mW, they're only used in circuits that dissipate very little power and are extremely constrained in volume. An even smaller metric 0201 package (0.2 mm x 0.1 mm) has been announced, but is not in production yet. But even when they do show up in manufacturer's catalogs, don't expect them to pop up everywhere: most pick-and-place robots are not accurate enough to handle them, so they will likely remain a niche product.

Capacitors can be scaled down as well, but this reduces their capacitance. The formula for calculating the capacitance of a parallel-place capacitor is , where A is the area of the plates, d is the distance between them, and ε is the dielectric constant (a property of the material in the middle). If you miniaturize a capacitor, which is basically a flat device, you have to reduce the area and therefore the capacitance. If you still want to pack a lot of nanofarads in a small volume, the only option is to stack several layers on top of each other. Thanks to advances in materials and manufacturing, which also enable thin films (small d ) and special dielectrics (with larger ε ), capacitors have shrunk in size significantly over the past few decades.

An idealized parallel-plate capacitor. Credit: inductiveload, public domain

The smallest capacitors available today are packaged in the ultra-small metric 0201 package: just 0.25 mm x 0.125 mm. Their capacitance is limited to a still useful 100 nF with a 6.3 V maximum operating voltage. Again, these packages are so tiny that advanced equipment is needed to process them, limiting their widespread adoption.

For inductors, the story is a bit trickier. The inductance of a straight coil is given by , where N is the number of turns, A is the cross-sectional area of the coil, l is its length and μ is a material constant (the magnetic permeability). If you scale down all dimensions by half, you halve the inductance as well. However, the resistance of the wire remains the same: this is because the wire's length and cross section are both reduced to a quarter of their original value. This means you end up with the same resistance for half the inductance, and therefore you've halved the quality (Q) factor of your coil.

Almost invisible: three 0201 (metric) capacitors. Image credit: Murata Electronics

The smallest commercially available discrete inductors are in the imperial 01005 size (0.4 mm x 0.2 mm). These go up to 56 nH, with several Ohms of resistance. Inductors in the ultra-small metric 0201 package were announced back in 2014 but apparently never brought to market.

There have been some efforts to get around the inductor's physical limitations by using a phenomenon called kinetic inductance, which can be observed in coils made of graphene. But even that gives an improvement of perhaps 50%, if it can be made in a commercially viable way. In the end, coils simply don't miniaturize very well. But this doesn't have to be a problem if your circuits work at high frequencies. If your signals are in the GHz range, then a coil of a few nH is often enough.

It's Not Just the Components

This brings us to another thing that has been minaturized over the past century, but which you might not notice right away: the wavelengths we use for communication. Early radio broadcasts used medium wave AM frequencies around 1 MHz, with a wavelength of about 300 meters. The FM band centered around 100 MHz, or three meters, became popular around the 1960s, while today we mostly use 4G communications around 1 or 2 GHz, about 20 cm. Higher frequencies mean more capacity to transmit information, and it's because of miniaturization that we have cheap, reliable and power efficient radios working at these frequencies.

Shrinking wavelengths enabled shrinking antennas, since their size is directly related to the frequency they need to transmit or receive. The fact that mobile phones today don't need long protruding antennas is thanks to the fact that they exclusively communicate at GHz frequencies, for which the antennas only need to be around one centimeter long. This is also why most phones that still contain an FM receiver require you to plug in your headphones before using it: the radio needs to use the headphone's wires as an antenna to get enough signal strength out of those meter-long waves.

As for the circuits connected to our tiny antennas, they actually become easier to make when they're smaller. This is not just because the transistors become faster, but also because transmission line effects are less of an issue. In a nutshell, when a piece of wire is longer than about one tenth of a wavelength, you need to take the phase shift along its length into account when designing your circuit. At 2.4 GHz this means that just one centimeter of wire already affects your circuit; quite a headache if you're soldering discrete components together, but not a problem if you're laying out circuits on a few square millimeters.

How Low Can You Go?

It has become a bit of a recurring theme in tech journalism to either predict the demise of Moore's law, or to show how those predictions are wrong time and again. The fact remains that the three players still competing at the cutting edge of this game -- Intel, Samsung and TSMC -- keep on squeezing ever more functionality into each square micron, and are planning several improved generations of chips into the future. Even if the strides they make at each step may not be as great as they were two decades ago, miniaturization of transistors continues nonetheless.

As for discrete components however, it seems like we've reached a natural limit: making them smaller doesn't improve their performance, and the smallest components currently available are smaller than the vast majority of use cases need. There doesn't seem to be a Moore's law for discretes, but if there were one, we would love to see how far one could push the SMD Soldering Challenge.

Header image: Jon Sullivan, public domain.

#engineering #featured #parts #antennas #capacitors #discretecomponents #inductors #miniaturization #mooreslaw #resistors #transistors

Les opérateurs de RansomExx diffusent des données relatives à :

• 🇹🇼 [31.18GiB] WT Microelectronics Co., Ltd. (wtmec.com)

Established in 1993, WT Microelectronics is a leading professional service provider focusing on the global semiconductor distribution industry. Company's products include linear IC, applied IC, admixture semaphore IC, logic IC, image detecting IC, and memory IC. Wintech acts as an agent for Texas Instruments, Fairchild, ST Microelectronics, Marvell, Wolfson, and Bowoon. By providing superior supply chain management services to both vendors and customers, WT has successfully positioned itself as a pivotal liaison, bridging upstream and downstream partners. Carried 55,000＋types of components. Served 8,000＋customers. Processed 690,000＋orders. Delivered 28,000,000,000＋ chips. Created NT$353.2 billion in annual sales.

• 🇪🇨 [11.23GiB] Corporación Nacional de Telecomunicación (cnt.gob.ec)

Public telecommunications company in Ecuador that offers fixed telephony services local, regional and international, Internet Access (Dial-Up, DSL, mobile Internet), satellite television and mobile telephony in Ecuadorian territory. On July 30, 2010 was the official merger of the Corporación Nacional de Telecomunicaciones, CNT EP with Alegro mobile phone company, allowing the company to enhance their product portfolio by focusing efforts in the packaging business and converged services technology.

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Les opérateurs de RansomExx diffusent des données relatives à :

• 🇹🇼 [5.15GiB] Walsin Technology Corporation, Ltd. (walsin.com)

The world's leading manufacturer of passive components with one-stop-shop product portfolio and worldwide delivery platform. The company's product lineup includes multiple-layer ceramic chip (MLCC) capacitor/array, chip-resistor/array & networks, RF . Walsin Technology Corporation, membre de l'alliance Passive Systems Alliance Taiwan, est une société taïwanaise dont l'activité principale est la fabrication, le traitement et la vente de condensateurs multicouches à puces céramiques (MLCC), de résistances à puces, de dispositifs à haute fréquence (HF) et de dispositifs à radiofréquence.

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Not practical yet, but hints at a future when inductors can be miniaturised.

"Writing in Nature, Yokouchi et al. report a quantum-mechanical inductor, called an emergent inductor, that uses the electric field produced by the current-driven dynamics observed for intricate structures of magnetic moments (spins) in a magnet. Notably, this device has an inductance that is inversely proportional to its area and does not require a coil or a core"

https://www.nature.com/articles/d41586-020-02721-7

#Inductors #Electronics