Doug Nix

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  • Step-by-step—Class 11

    Step-by-step—Class 11

    1. Step by step – 1st Class
    2. Step-by-Step – 2nd Class
    3. Amateur Radio Codes of Conduct
    4. Step-by-Step – 3rd Class
    5. Step-by-Step – Class 4a
    6. Step-by-Step – Classes 4b & 4c
    7. Step-by-Step—Class 5
    8. Step-by-Step—Class 6
    9. Step-by-Step—Class 7
    10. Step-by-Step—Class 8a
    11. Step-by-Step—Class 8b
    12. Step-by-Step—Class 9
    13. Step-by-Step—Class 10
    14. Step-by-step—Class 11
    15. A Modern Code of Conduct and Ethics for Amateur Radio
    16. Step-by-step—Class 12
    17. Step-by-step—Class 13
    18. Step-by-step—Class 14
    19. Step-by-step—Class 15
    20. Step-by-step—Class 16
    21. Step-by-step—Class 17
    22. Reflection: My Amateur Radio Journey So Far
    23. Authorized to Transmit

    Building the Heart of the Shack

    When I was starting out in electronics in the mid-1980s, the idea of having a well-equipped radio shack had a kind of magic to it (it still does!).

    Not my shack, but it sure looks nice!

    At GFC Hammond in Guelph, where I first worked as a production test technician, I’d wander through the Hammond Museum of Radio on my lunch breaks, looking at the early receivers and transmitters that once connected Canada to the world. Those glass-tubed wonders seemed impossibly far from my world of circuit boards and switching supplies—but they planted the seed.

    Now, after years of working with safety systems, standards, and industrial controls, I find the simplicity of amateur radio refreshing. It’s a space where you can still build something tangible—wire, solder, and ingenuity turning into a working station that reaches across continents.

    Choosing the Right Space

    Al Penny starts Chapter 11 of the RAC course with a point that sounds simple but matters immensely: location is everything. Whether your shack is in the basement, a spare room, or tucked into a corner of your office, comfort, safety, and practicality all count. I’ve seen too many setups crammed into damp basements where corrosion becomes a silent saboteur. On the flip side, attic shacks turn into saunas by July. [1]

    The key is access—to power, grounding, and a clean route for feed lines and rotator cables. The rest—furniture, décor, and clever cable management—comes later. What matters most is making a space you actually want to spend time in. After all, this is where you’ll chase DX at 2 a.m., rebuild an antenna tuner that “worked fine yesterday,” and tinker endlessly with wiring diagrams.

    The Gear: New, Used, and Everything in Between

    Penny gives solid advice on buying equipment: define your needs first, then go shopping. The market today is overflowing with excellent radios, from handhelds that fit in a jacket pocket to sophisticated HF rigs that rival commercial equipment. The temptation to overspend is real.

    Buying used gear can be a fantastic way to stretch your budget—but it’s a bit like dating. You need to know what you’re getting into. Check for drift, dirty switches, and tell-tale signs of neglect. A radio that looks like it’s been through a sandstorm probably has. But when you find the right piece—an older Icom or Kenwood that’s been well-loved and well-maintained—it can serve faithfully for years.

    Whether you buy new or used, read the reviews, talk to other hams, and don’t underestimate the value of a dealer warranty. Sometimes peace of mind is worth a few extra dollars.

    The Joy of Hamfests

    There’s no better way to get your hands on gear—and stories—than at a hamfest. From Dayton’s legendary Hamvention to our own HAM-EX and York Region shows here in Ontario, these events are part swap meet, part social gathering, and part carnival. You might arrive looking for a particular SWR meter and leave with a trunk full of mystery boxes and a new circle of friends.

    2022 Hamilton Ontario Hamfest

    It’s that mix of technical curiosity and community that keeps this hobby alive. Long before online marketplaces and Discord chats, the hamfest was where you learned, traded, and laughed with people who spoke your language—literally and figuratively.

    The Supporting Cast

    A good station isn’t just a transceiver and a mic. Penny’s chapter reads like a love letter to the small but vital accessories that make a station run smoothly: the SWR meter, the dummy load, the antenna tuner, and those ingenious antenna switches that save you from untangling coax spaghetti. Each one has a role in keeping the station efficient, safe, and operational.

    Rectangular black metal device with ventilation slots on the top and sides, labeled “1.5KW HF-UHF Dry Dummy Load 1–650 MHz.” The front panel features an SO-239 coaxial connector and the brand name “MFJ” along with “Model MFJ-264” and “MFJ Enterprises, Inc., Starkville, MS USA."
    1.5 kW MFJ Dry Dummy Load
    Two-needle SWR meter.
    Two-needle SWR meter.

    His explanation of the antenna tuner—how it doesn’t “tune the antenna” at all but instead tricks your transmitter into seeing the load it wants—is a reminder of how much practical wisdom hides in this hobby.

    Antenna Tuner

    You learn theory, sure, but you also learn the gentle art of “coax diplomacy”: keeping your rig happy, your feedline loss low, and your neighbours blissfully unaware of their TV flickering every time you key up.

    A Final Thought

    In an age of plug-and-play everything, there’s something grounding—literally and figuratively—about building your own station. Each choice, from desk height to antenna orientation, reflects your habits and curiosity. You can buy the fanciest SDR on the market, but it won’t mean much until you’ve wrestled with grounding straps, tuned an antenna by ear, and smelled a resistor or two giving up the ghost.

    For me, that’s the heart of amateur radio: hands-on, imperfect, and wonderfully human. Every station tells a story—not just of frequencies and filters, but of persistence, learning, and connection.

    Bibliography

    [1] A. Penney, ‘Establishing and Equipping a Station’, presented at the RAC Basic Certificate Course, Radio Amateurs of Canada, Canada, Nov. 02, 2025. Accessed: Nov. 02, 2025. [Online]. Available: https://www.rac.ca/

  • Step-by-Step—Class 10

    Step-by-Step—Class 10

    1. Step by step – 1st Class
    2. Step-by-Step – 2nd Class
    3. Amateur Radio Codes of Conduct
    4. Step-by-Step – 3rd Class
    5. Step-by-Step – Class 4a
    6. Step-by-Step – Classes 4b & 4c
    7. Step-by-Step—Class 5
    8. Step-by-Step—Class 6
    9. Step-by-Step—Class 7
    10. Step-by-Step—Class 8a
    11. Step-by-Step—Class 8b
    12. Step-by-Step—Class 9
    13. Step-by-Step—Class 10
    14. Step-by-step—Class 11
    15. A Modern Code of Conduct and Ethics for Amateur Radio
    16. Step-by-step—Class 12
    17. Step-by-step—Class 13
    18. Step-by-step—Class 14
    19. Step-by-step—Class 15
    20. Step-by-step—Class 16
    21. Step-by-step—Class 17
    22. Reflection: My Amateur Radio Journey So Far
    23. Authorized to Transmit
    My Hammond Manufacturing business card from 1989.
    My business card at GFC prior to the spin-off of the organization in 1989

    From Hammond to High Efficiency: Reflections on Power Supplies Then and Now

    In 1985, when I started my career at GFC Hammond Electronics in Guelph, Ontario, the hum of transformers and the scent of flux were part of my daily environment. As a production test technician, my job was to test and repair linear and switching power supplies—work that gave me an intuitive feel for what really makes electronic systems tick.

    Four men kneel in front of a sign reading “Hammond Manufacturing Company Limited” with divisions listed as “GFC/Hammond Electronics Division,” “Hammond Electronics Division,” and “Hammond Museum of Radio.” The sign is mounted outside an industrial building with white and dark metal siding. Two of the men wear light blue lab coats, and the group poses on a grassy area under a clear blue sky.
    1989 – L-R: Bruce Ritchie (QA Manager), me, a Korean colleague, and Jerry Williamson (Manufacturing Engineering) in front of the Curtis Road plant in 1989.

    The Hammond facility on Curtis Road was a fascinating place for someone just starting out in electronics. The Hammond Museum of Radio was located in the same building, and the local amateur radio club’s repeater, VE3HC, had a tower at the back of the plant. Fred Hammond himself—whose name is etched into Canadian radio history—could often be found tinkering or chatting with staff. For a young technician like me, those were inspiring encounters that linked the practical side of my work to a century of radio innovation.

    Understanding the Foundations

    To appreciate modern power supplies, it helps to look back to the origins of the electrical grid itself. The way we generate and distribute electricity has always shaped the way we convert it.

    Thomas Alva Edison, three-quarter length portrait, seated, facing front". Photographic print.
    Thomas Edison, 1922
    Photograph of George Westinghouse Jr. (October 6, 1846 – March 12, 1914) in 1884 - American entrepreneur and engineer based in Pennsylvania
    George Westinghouse Jr., 1884
    Nikola Tesla about 1890
    Nikola Tesla about 1890

    In the late 19th century, the “War of the Currents” pitted two of the era’s greatest inventors against each other: Thomas Edison, who favoured direct current (DC), and Nikola Tesla, whose alternating current (AC) system was backed by George Westinghouse. Edison’s DC approach had the advantage of simplicity and safety, but it couldn’t transmit power efficiently over long distances. Tesla’s AC system, on the other hand, used transformers to step voltage up for transmission and down for use—making large-scale distribution practical for the first time.

    The debate was settled decisively in 1895, when the Niagara Falls hydroelectric plant—built by Westinghouse—demonstrated the superiority of AC power. The plant’s generators produced 25 Hz alternating current, a frequency chosen as a compromise between efficient motor operation and adequate lighting performance. While 25 Hz served early heavy industry well, it wasn’t ideal for all applications. By the early 20th century, 60 Hz had become North America’s standard, striking a balance between efficiency and performance for the emerging electrical grid. [2]

    Across the Atlantic, Europe standardized on 50 Hz, largely through the influence of engineers at AEG and the VDE. They determined that 50 Hz offered the best trade-off between voltage drop, lighting flicker, and motor design. The choice was also elegantly compatible with the metric system—a detail the Germans took no small satisfaction in noting. [1]

    These early engineering decisions still echo in our wall sockets today. The world’s grids may differ by frequency and voltage, but they all deliver alternating current—a form of power distribution optimized for transmission, not for the needs of modern electronics.

    Why Electronics Need Conversion

    For electronic systems, line-frequency AC power isn’t directly useful. Radios, computers, and control circuits all require direct current (DC)—and not just any DC, but clean, stable, and precisely regulated voltage. This is where power converters come in: they transform AC into DC and sometimes back into AC at different frequencies for specialized uses, such as motor drives or RF systems.

    This need for efficient and reliable power conversion drives the evolution from linear to switch-mode power supplies—the very technologies I worked on daily at Hammond.

    Linear Power Supplies

    In a traditional linear power supply, the transformer does the heavy lifting, stepping up or down the voltage and isolating the circuit from the mains. The rectifier converts AC to DC—first through simple half- or full-wave circuits and later through the now-ubiquitous bridge rectifier. The resulting pulsating DC is smoothed by large electrolytic capacitors, which store charge between cycles to reduce ripple.

    Filtering and regulation define the character of a linear supply. Early designs used Zener diodes or discrete transistor regulators, which three-terminal IC regulators, such as the LM78xx series later replaced. Linear regulators operate in the transistor’s linear region, dropping excess voltage as heat—a simple, reliable, and noisy (in the thermal sense) way to achieve a stable output.

    Linear supplies have an unmistakable presence: heavy transformers, warm chassis, and that faint 120-Hz hum that signalled a tired filter capacitor. They were dependable, repairable, and forgiving—a good match for the analog age.

    Schematic diagram of a vacuum tube power supply circuit using a Hammond 270FX transformer and a 5U4GB rectifier tube. The primary side is connected to AC mains with a fuse and power switch. The secondary has a 275-0-275 V winding feeding the 5U4GB full-wave rectifier, along with 5 V and 6.3 V heater windings. The rectified DC passes through a multi-stage LC filter composed of Hammond 193J (10 H, 82 Ω) and Hammond 158Q (5 H, 150 Ω) chokes, plus 32 µF and 100 µF filter capacitors. A 350 Ω 5 W resistor provides additional filtering, and a 470 kΩ bleeder resistor is connected to ground. The output B+ voltage is approximately 272 V DC.
    A Vacuum tube rectified DC power supply for a tube amplifier. The B+ voltage has the same function as Vcc in semiconductor circuits.

    Because linear supplies operate in the linear region of the transistors, the difference between the raw rectified DC and the output voltage must be dropped across the regulator transistor(s), resulting in significant I2R losses in those devices. [4], [5].

    Schematic diagram of a regulated DC power supply using a full-wave bridge rectifier and an LM7805 voltage regulator. AC voltage from a transformer secondary is fed into a bridge rectifier made up of four diodes (D1–D4) arranged in a diamond pattern. The rectified output is filtered by capacitors C1 and C2, then passed through an LM7805 regulator that outputs a stable +5 V DC. A final smoothing capacitor C3 is connected at the output.
    Linear 5 Vdc regulated power supply. The rating of the LM7805 regulator limits the output current from this design. [4]

    From Linear to Switching

    By the time I arrived at Hammond, switch-mode power supplies (SMPS) were reshaping the field. Instead of relying on bulky transformers at 60 Hz, SMPS designs rectify the AC first, then chop the DC at high frequency—tens or hundreds of kilohertz—using transistors operating in saturation (fully on or off). The high frequency allows much smaller transformers and capacitors, dramatically improving efficiency and reducing weight.

    Of course, early SMPS units had their quirks. Without proper filtering—MOVs, chokes, and capacitors on the input—they could fill an HF receiver’s spectrum with a wash of interference. However, as designs matured, improved EMI filters, shielding, and power factor correction made switching supplies both quieter and more efficient.

    How switching power supplies work

    In switch-mode supplies, the AC mains power is first rectified. Then, the DC power is converted back to AC at a much higher frequency, allowing smaller, lighter, and less expensive transformers to be used to provide the lower AC voltages needed for the load(s). The use of higher frequencies also means that the filter capacitors can be smaller in size and lighter in weight. Additional inductors are required to prevent high-frequency switching noise from transferring to the load side of the supply. The benefit is that the primary power converter can use pulse-width modulation, keeping the switching transistors operating in their saturation mode, and thereby reducing the I2R losses in the transistors that result in waste heat. [6], [7].

    Circuit diagram of a TL594-based switch mode power supply (SMPS) with battery over- and under-voltage protection, designed by Gary Lecomte. The TL594 PWM controller IC drives two MOSFETs (IRF640 or STP75NF75) connected in a push-pull configuration to a ferrite core transformer (T1). The primary side operates from a 12 V DC input, filtered by a 220 µF capacitor. Frequency control is set by resistors Ra (8.2 kΩ), Rb (10 kΩ), and capacitor C1 (0.0022 µF), producing a switching frequency between 35 kHz and 70 kHz depending on adjustment. A 2N3904 transistor provides voltage error feedback for regulation. The secondary winding of the transformer is rectified by a diode bridge to produce a DC output. The circuit includes overvoltage protection at about 15.5 V and undervoltage protection at about 11 V, with additional notes explaining frequency and dead-time adjustment.

    What’s easy to forget is that early SMPS units were not always well-behaved neighbours in a radio shack. Without proper transient filtering—MOVs, chokes, and capacitors on the input—they could turn the HF spectrum into a wash of hash. Today’s designs, with improved EMI filtering and power factor correction, are worlds better.

    Lessons That Endure

    Looking back, my time at Hammond laid a foundation for everything that followed. Power supplies are not just supporting components; they’re the heart of every electronic system. If the supply isn’t clean, stable, and appropriately rated, nothing downstream behaves as intended.

    Al Penney’s excellent presentation [3] on power supplies for amateur radio operators captures that same truth: whether you’re winding transformers, testing LM7805 regulators, or designing 90%-efficient SMPS circuits, the goal remains constant—reliable, safe power delivery.

    For me, that journey began on a test bench in Guelph, soldering iron in one hand and scope probe in the other—under the same roof where Fred Hammond preserved the history of radio. It’s a fitting reminder that every modern innovation, no matter how advanced, still rests on a well-built power supply.

    References

    [1] G. Neidhöfer, ‘50-Hz Frequency [History]’, IEEE Power and Energy Mag., vol. 9, no. 4, pp. 66–81, July 2011, doi: 10.1109/MPE.2011.941165.

    [2] P. Mixon, ‘Technical origins of 60 Hz as the standard AC frequency in North America’, IEEE Power Eng. Rev., vol. 19, no. 3, pp. 35–37, Mar. 1999, doi: 10.1109/MPER.1999.1036103.

    [3] A. Penney, Power Supplies, VO1NO, RAC Basic Amateur Radio Course, 2023.

    [4] O. M. Urias, ‘How to Build a DC Linear Power Supply’, Build Electronic Circuits. Accessed: Oct. 30, 2025. [Online]. Available: https://www.build-electronic-circuits.com/linear-power-supply/

    [5] ‘Power Supply Circuits’, in Lessons in Electric Circuits. Accessed: Oct. 29, 2025. [Online]. Available: https://www.allaboutcircuits.com/textbook/semiconductors/chpt-9/power-supply-circuits/

    [6] “Switching Mode Power Supplies,” Wikipedia. [Online]. Available: https://en.wikipedia.org/wiki/Switched-mode_power_supply

    [7] C. Atwell, ‘A Brief History of Switching Power Supplies’, Electronic Design. Accessed: Nov. 07, 2025. [Online]. Available: https://www.electronicdesign.com/technologies/power/article/55040799/electronic-design-switching-power-supply-history-from-theory-to-design-essential

  • Step-by-Step—Class 9

    Step-by-Step—Class 9

    1. Step by step – 1st Class
    2. Step-by-Step – 2nd Class
    3. Amateur Radio Codes of Conduct
    4. Step-by-Step – 3rd Class
    5. Step-by-Step – Class 4a
    6. Step-by-Step – Classes 4b & 4c
    7. Step-by-Step—Class 5
    8. Step-by-Step—Class 6
    9. Step-by-Step—Class 7
    10. Step-by-Step—Class 8a
    11. Step-by-Step—Class 8b
    12. Step-by-Step—Class 9
    13. Step-by-Step—Class 10
    14. Step-by-step—Class 11
    15. A Modern Code of Conduct and Ethics for Amateur Radio
    16. Step-by-step—Class 12
    17. Step-by-step—Class 13
    18. Step-by-step—Class 14
    19. Step-by-step—Class 15
    20. Step-by-step—Class 16
    21. Step-by-step—Class 17
    22. Reflection: My Amateur Radio Journey So Far
    23. Authorized to Transmit

    From Vacuum Tubes to Transistors: A Personal Reflection on the Building Blocks of Modern Electronics

    Every once in a while, I come across a presentation that reminds me just how remarkable our journey in electronics has been. Al Penney’s “Diodes, Transistors and Tubes”, class 9 in the RAC Basic Qualification Course, is one of those — a concise, clear walk-through the history and physics that underpin virtually everything we take for granted in modern technology. [1]

    For anyone who’s ever built a circuit, troubleshot a control system, or simply wondered how a radio turns electromagnetic waves into sound, Al’s lecture is a reminder that the devices we use daily rest on a few elegant physical principles.

    Atoms, Electrons, and the Dance of Conductivity

    Al starts where all good electronics stories should: the atom. Protons, neutrons, and electrons — familiar from high school physics — become the players in a complex dance that determines whether a material is a conductor, an insulator, or something in between.

    Semiconductors sit in that fascinating “in-between” zone. By carefully introducing impurities, or doping, engineers can coax silicon or germanium into behaving predictably — letting electrons move when we want them to and stopping them when we don’t. That’s the foundation of everything from radio detectors to modern CPUs.

    The Simple Genius of the Diode

    The humble semiconductor diode, as Al explains, is just a P–N junction that lets current flow one way but not the other.

    Diagram of a PN junction diode showing both its physical structure and circuit symbol. The upper part depicts a semiconductor junction with p-type silicon on the left (anode) and n-type silicon on the right (cathode). The lower part shows the corresponding diode circuit symbol with the triangle representing current flow direction toward the vertical line, labelled with anode and cathode terminals.
    A p–n junction diode. The circuit symbol is also shown.
    By Raffamaiden – Own work, CC BY-SA 3.0, Link

    It’s the electronic equivalent of a check valve — elegantly simple, profoundly useful. With that one device, we can rectify AC into DC, demodulate radio signals, or stabilize voltage with a Zener diode.

    I’ve always appreciated how intuitively physical these analogies are. Whether you think of diodes as electrical check valves or semiconductors as engineered crystals, they connect the abstract world of physics with the very real world of current and voltage.

    Transistors: The Revolution in a Grain of Germanium

    A close-up photograph of the first transistor, the point-contact transistor invented at Bell Labs in 1947. The device is mounted on a clear acrylic stand, showing delicate wires connected to a small triangular germanium crystal on a metal base. Above the crystal, a bent wire spring applies pressure to the contacts. The setup includes fine leads and soldered connections, demonstrating the experimental nature of the original prototype used in early solid-state electronics research.
    The first transistor ever made, built by John Bardeen, William Shockley and Walter H. Brattain of Bell Labs in 1947. Original exhibited in Bell Laboratories. [2]
    Unitronic, CC BY-SA 3.0, via Wikimedia Commons
    Side-by-side image showing a point-contact transistor and its schematic diagram. On the left is a close-up photograph of an early germanium transistor with labeled components: emitter, collector, base, and a spring pressing a gold foil contact onto the germanium crystal mounted on a metal base. On the right is a simplified diagram showing the structure: a plastic wedge holding the emitter and collector contacts pressed onto a germanium substrate, with a thin razor cut between them to separate the two contacts, and labels for emitter, collector, base, spring, gold foil, and germanium.
    The first point-contact transistor is on the left. On the right is the schematic representation. 
    Image courtesy of AT&T.

    Then came the transistor — arguably the most transformative invention of the twentieth century. Al’s slides capture both the historical significance and the practical brilliance of that moment in 1947 when Bardeen and Brattain’s point-contact transistor first amplified a signal.

    Before that, we relied on vacuum tubes: glowing, fragile, power-hungry devices that filled radio chassis and computer rooms.

    A close-up photograph of an electronic vacuum tube, also known as a thermionic valve. The glass envelope is clear, showing the internal metal electrodes and grid structures. The tube has a metal base with several pins for insertion into a socket, and the top of the glass has a slightly darkened getter flash. The image is taken on a white background, highlighting the tube’s reflective surfaces and cylindrical shape.
    Vacuum Tube

    The transistor changed everything. It was small, efficient, rugged — and as Al notes, it enabled everything from portable radios to the computers that now run our world.

    Vintage 1940s Operadio Tube Amplifier [3]

    As someone who’s spent a career around control systems and functional safety, I find the transistor’s evolution from that sliver of germanium to today’s silicon MOSFETs a story of both science and engineering perseverance. Billions of transistors now sit on a chip smaller than your fingernail — each one still following the same basic principles first demonstrated in a Bell Labs lab bench.

    Amplifiers and the Art of Control

    One of Al’s most practical sections deals with amplification.

    Circuit diagram of a 25-watt audio amplifier using an integrated circuit (IC) TDA2040. The schematic shows input, power, and output stages. The audio input passes through capacitor C1 and resistor R1 to the non-inverting input of the IC (pin 1). Feedback is provided via resistors R2 and R3 and capacitor C2. Power supply decoupling capacitors C4 and C5 are connected to ±17V rails. The amplifier output drives a loudspeaker (LS1) through resistor R4 and capacitor C3.
    25 Watt Amplifier Circuit Diagram

    Whether we’re talking about boosting a microphone signal, driving a loudspeaker, or switching a safety relay, the amplifier’s purpose is the same — to make a small signal powerful enough to do useful work.

    Types of Transistors: Classification (BJT, JFET, MOSFET & IGBT) [4]

    Transistors and FETs handle this task differently, but the core idea is universal: use a small input to control a larger output. In machinery safety and control, this principle is evident everywhere — from sensor conditioning to PLC inputs and output stages, as well as pneumatics and hydraulics.

    Reflections on a Legacy of Innovation

    Al’s presentation closes with a nod to vacuum tubes — those glowing ancestors of the solid-state devices we know today. While they’ve been mostly replaced, they still hold a special place in audio and RF engineering for their distinctive performance characteristics.

    Vacuum tubes are still commonly used in specialized radio applications, particularly in high-power RF transmitters, including commercial radio and television broadcasting, amateur radio, and military communication systems. Their ability to handle high voltages, high power levels, and their linear amplification characteristics make them preferred in these settings where solid-state devices may be less reliable or unable to perform as well. Vacuum tubes are also valued for their durability in harsh environments, such as those with radiation or electromagnetic pulses (EMP), which is particularly important for military and aerospace applications.

    Key Radio Applications of Vacuum Tubes Today

    • High-Power Radio Transmitters: Commercial broadcast stations still use vacuum tubes for final power amplification due to their capacity to handle large RF power loads.
    • Amateur Radio Equipment: Many ham radio operators prefer tube-based transmitters for their superior signal handling, natural overload tolerance, and call sign authenticity in traditional equipment.
    • Military Communications: Vacuum tubes are preferred in certain military radios because of their robustness against EMP and radiation, ensuring reliable operation under extreme conditions.
    • Specialized Scientific and Industrial RF Systems: Vacuum tubes are used in some radar, industrial RF heating, and scientific instruments requiring high voltage and power.
    A British radio transmitter from the early 1920s, used for some of the first radio broadcasts by the British Broadcasting Corporation (BBC). The four early power triode valves (vacuum tubes) used in parallel resemble the 4 kW Marconi MT1 valves, developed by Marconi Co. engineer H. L. Round, which operated at 12,000 volts on the plate (anode). Blythe House Science Museum stores tour, London.
    By John Cummings – Own work, CC BY-SA 3.0, Link
    This beautiful example of home construction by Dick Stevens, W1QWJ, produces the “full gallon” (full, legally permitted power) on the 50 MHz band. The single tube is a 4CX1600B tetrode. [14]

    Additional Contemporary Uses Related to Radio

    • Vacuum tubes find niche roles in audio amplification equipment connected to radio receivers due to their characteristic sound.
    • Vacuum tube audiophile amplifiers are increasingly common, where their soft roll off when over-driven yield a much better sound than the harsh clipping that transistors give under similar conditions.
    • Some hybrid designs combine vacuum tube stages with solid-state components in modern radio equipment.
    Oilily A88 Vacuum Tube Integrated Amplifier, 45W+45W Class AB, EL34/KT88 Tube Amplifier with Triode & Ultra-Linear Mode, External Bias Adjustment, High-Fidelity Sound for Audiophiles (Black) [15]

    Thus, while transistors have largely replaced vacuum tubes in most consumer electronics, vacuum tubes remain essential in applications where their unique electrical and physical properties provide advantages that solid-state devices cannot fully match [5][6][7][8].

    Reading through this material reminded me that understanding where our technology comes from isn’t just nostalgic — it’s essential. Whether we’re designing safety systems, writing standards, or just tinkering in the shop, the principles that Al Penney lays out are as relevant today as they were when the first transistor clicked into life.

    In short: the story of diodes, transistors, and tubes isn’t just about components — it’s about curiosity, experimentation, and the human drive to control and harness electricity.

    Thanks, Al Penney (VO1NO), for reminding us how far we’ve come — and how much of that journey is still worth exploring.

    Bibliography

    [1] A. Penney, ‘Chapter 9 – Diodes, Transistors, and Tubes’, Radio Amateurs of Canada, Canada, Nov. 02, 2025. Accessed: Nov. 02, 2025. [Online]. Available: https://www.rac.ca/

    [2] J. T. Rubin, ‘The Invention of the Transistor’. Accessed: Oct. 29, 2025. [Online]. Available: https://www.juliantrubin.com/bigten/transistorexperiments.html

    [3] ‘Vintage 1940s Operadio Tube Amplifier Guitar Lap Steel Amp 5641 Speaker’, Worthpoint.com. Accessed: Nov. 01, 2025. [Online]. Available: https://www.worthpoint.com/worthopedia/vintage-1940s-operadio-tube-amplifier-4596304184

    [4] A. Singh, ‘Types of Transistors: Classification (BJT, JFET, MOSFET & IGBT)’, Hackatronic. Accessed: Nov. 01, 2025. [Online]. Available: https://www.hackatronic.com/types-of-transistors-classification-bjt-jfet-mosfet-igbt/

    [5] Vacuum Tubes: Complete Guide to Types, Applications & … https://www.blikai.com/blog/vacuumtube/vacuum-tubes-complete-guide-to-types-applications-modern-roles

    [6] Are Vacuum Tubes Still Used (& What Are They Used for)? https://pentalabs.com/blogs/tube-talk/are-vacuum-tubes-still-used

    [7] When Old is Gold: Harnessing the Power of Vintage … https://www.radiodesigngroup.com/blog/when-old-is-gold-harnessing-the-power-of-vintage-technology-for-modern-applications

    [8] Vacuum Tube Market Size & Share 2025-2032 https://www.360iresearch.com/library/intelligence/vacuum-tube

    [9] Brief Overview of Vacuum Tubes and Circuits https://www.bristolwatch.com/science/vacuum_tubes.htm

    [10] Vacuum tubes and modern uses for them : r/ECE https://www.reddit.com/r/ECE/comments/4hmi03/vacuum_tubes_and_modern_uses_for_them/

    [11] List of vacuum tubes https://en.wikipedia.org/wiki/List_of_vacuum_tubes

    [12] Modern Radio Technology Comparison to Tube Radio https://www.youtube.com/watch?v=GVXwsdsIyiI

    [13] Unlocking the Future of Vacuum Tube: Growth and Trends … https://www.marketreportanalytics.com/reports/vacuum-tube-376095

    [14] H. W. Silver, ‘Vacuum Tubes’, Nuts and Volts Magazine, no. November, pp. 8–11, 2017. Accessed: Nov. 01, 2025. [Online]. Available: https://www.nutsvolts.com/magazine/article/vacuum-tubes

    [15] ‘Oilily A88 Vacuum Tube Integrated Amplifier, 45W+45W Class AB, EL34/KT88 Tube Amplifier with Triode & Ultra-Linear Mode, External Bias Adjustment, High-Fidelity Sound for Audiophiles (Black)’, Tube Amplifier Reviews. Accessed: Nov. 01, 2025. [Online]. Available: https://tubeamplifierreviews.com/oilily-a88-vacuum-tube-integrated-amplifier-45w45w-class-ab-el34-kt88-tube-amplifier-with-triode-ultra-linear-mode-external-bias-adjustment-high-fidelity-sound-for-audiophiles-black/

  • Step-by-Step—Class 8b

    Step-by-Step—Class 8b

    1. Step by step – 1st Class
    2. Step-by-Step – 2nd Class
    3. Amateur Radio Codes of Conduct
    4. Step-by-Step – 3rd Class
    5. Step-by-Step – Class 4a
    6. Step-by-Step – Classes 4b & 4c
    7. Step-by-Step—Class 5
    8. Step-by-Step—Class 6
    9. Step-by-Step—Class 7
    10. Step-by-Step—Class 8a
    11. Step-by-Step—Class 8b
    12. Step-by-Step—Class 9
    13. Step-by-Step—Class 10
    14. Step-by-step—Class 11
    15. A Modern Code of Conduct and Ethics for Amateur Radio
    16. Step-by-step—Class 12
    17. Step-by-step—Class 13
    18. Step-by-step—Class 14
    19. Step-by-step—Class 15
    20. Step-by-step—Class 16
    21. Step-by-step—Class 17
    22. Reflection: My Amateur Radio Journey So Far
    23. Authorized to Transmit

    Back to Basics: Practical Antennas and the Beauty of Simplicity

    When I first started in electronics back in the mid-’80s, one of the first things I learned was that good design doesn’t always mean complex design. Nowhere is that truer than with antennas. Chapter 8B of the RAC Basic Certificate Course reminded me of something many of us tend to forget: the simplest antennas often work the best.

    (more…)
  • Step-by-Step—Class 8a

    Step-by-Step—Class 8a

    1. Step by step – 1st Class
    2. Step-by-Step – 2nd Class
    3. Amateur Radio Codes of Conduct
    4. Step-by-Step – 3rd Class
    5. Step-by-Step – Class 4a
    6. Step-by-Step – Classes 4b & 4c
    7. Step-by-Step—Class 5
    8. Step-by-Step—Class 6
    9. Step-by-Step—Class 7
    10. Step-by-Step—Class 8a
    11. Step-by-Step—Class 8b
    12. Step-by-Step—Class 9
    13. Step-by-Step—Class 10
    14. Step-by-step—Class 11
    15. A Modern Code of Conduct and Ethics for Amateur Radio
    16. Step-by-step—Class 12
    17. Step-by-step—Class 13
    18. Step-by-step—Class 14
    19. Step-by-step—Class 15
    20. Step-by-step—Class 16
    21. Step-by-step—Class 17
    22. Reflection: My Amateur Radio Journey So Far
    23. Authorized to Transmit

    Understanding Antennas: From Theory to the Sky

    This week in the RAC Amateur Radio course, we dug into one of the most fundamental — and fascinating — parts of radio communication: antennas. For many hams, the antenna is both the most visible and most mysterious part of the station.

    (more…)

  • Step-by-Step—Class 7

    1. Step by step – 1st Class
    2. Step-by-Step – 2nd Class
    3. Amateur Radio Codes of Conduct
    4. Step-by-Step – 3rd Class
    5. Step-by-Step – Class 4a
    6. Step-by-Step – Classes 4b & 4c
    7. Step-by-Step—Class 5
    8. Step-by-Step—Class 6
    9. Step-by-Step—Class 7
    10. Step-by-Step—Class 8a
    11. Step-by-Step—Class 8b
    12. Step-by-Step—Class 9
    13. Step-by-Step—Class 10
    14. Step-by-step—Class 11
    15. A Modern Code of Conduct and Ethics for Amateur Radio
    16. Step-by-step—Class 12
    17. Step-by-step—Class 13
    18. Step-by-step—Class 14
    19. Step-by-step—Class 15
    20. Step-by-step—Class 16
    21. Step-by-step—Class 17
    22. Reflection: My Amateur Radio Journey So Far
    23. Authorized to Transmit

    From Resistance to Reflection: Understanding Transmission Lines

    This week’s class dove into one of the most practical — and at times puzzling — parts of radio work: transmission lines.

    Examples of real-world tranmission line media [1]
    Examples of window line cable used for RF transmission lines
    image: DXEngineering

    At first glance, feedlines might seem like nothing more than fancy electrical cables, but as we learned, at radio frequencies the story changes completely. A transmission line isn’t just a wire — it’s a carefully balanced system that has to guide alternating current at very high frequencies, where even a few centimetres of cable can become a significant part of a wavelength.

    The Invisible Highway Between Radio and Antenna

    Our radios don’t magically send energy into space. The power has to travel along a transmission line — the “highway” between the transceiver and the antenna. But unlike ordinary power cords, transmission lines must manage reflections, impedance, and losses that don’t exist (or don’t matter) at lower frequencies.

    An example showing a transmission line’s elements: an inductor, capacitor, and two resistors. [2]

    Here, R and G represent, respectively, the resistance per unit length of the wire and the conductance per unit length of the dielectric that separates the conductors. L and C represent the inductance and capacitance per unit length of the transmission line.

    At radio frequencies, the series reactance is usually much greater than the series resistance, and the shunt reactance is usually much less than the shunt resistance, so we can assume that both resistances can be neglected. Neglecting R and G components, a lossless transmission line can be modelled by the infinite ladder network shown below.

    A model of an infinite transmission line following the characteristic impedance ladder network.

    That’s where characteristic impedance comes in. Every transmission line — whether it’s open-wire, twin-lead, or coaxial — has a natural impedance determined by its geometry and materials. Keep everything matched, and your power flows smoothly. Get it wrong, and some of that power comes screaming back down the line as reflected energy, forming standing waves.

    **Alt text:** Animated diagram showing a standing wave formed by the interference of two waves moving in opposite directions. The purple wave represents the incident and reflected waves, while the black wave shows their sum — the standing wave. Red dots mark the nodes, points of no displacement, along the wave where the amplitude remains zero.
    Incident and reflected waves create a standing wave

    When a continuous signal travels through a transmission line and encounters a load with a mismatched impedance, part of that signal reflects back toward the source. The original (incident) wave and the reflected wave move in opposite directions, and when they interact, they create interference — a standing wave. This standing wave is a real, physical effect along the cable’s length, producing points where the signal’s amplitude peaks and others where it dips. In some cases, the voltage at these peaks can exceed the original signal’s voltage, potentially leading to overheating or even damage to cables and components.

    Great tutorial on wave behaviour, including reflection and standing waves

    The AT&T archive video above effectively explains wave behaviour, impedance mismatches, reflections, and standing waves. It’s definitely worth watching if you want to gain a better understanding of waves and how they behave.

    Skin Effect

    The skin effect is the tendency of alternating current (AC) to flow primarily near the surface of a conductor rather than evenly through its entire cross-section. As frequency increases, the current becomes increasingly confined to a thin outer layer of the conductor.

    This behaviour occurs because the alternating magnetic field generated by AC induces eddy currents within the conductor. These opposing currents restrict the flow of current toward the surface, resulting in a non-uniform current density. The depth to which the current penetrates is referred to as the skin depth (δ).

    Diagram showing the cross-section of a cylindrical conductor with colour shading that represents higher current density near the surface and lower density toward the centre, illustrating the skin effect.
    Distribution of current flow in a cylindrical conductor, shown in cross-section.
    Biezl, Public domain, via Wikimedia Commons

    What Determines Skin Depth?

    Skin depth depends on both the frequency of the alternating current and the electrical and magnetic properties of the conductor. It is defined as the depth at which current density falls to 1/e (approximately 37%) of its surface value.

    As frequency increases, the skin depth decreases, meaning the current is confined to a thinner surface layer. This reduces the effective cross-sectional area available for current flow and increases the conductor’s effective resistance.

    Cause of skin effect
    By Biezl – Own work, Public Domain, Link

    A main current I flowing through a conductor induces a magnetic field H. If the current increases, as in this figure, the resulting rise in H induces separate, circulating eddy currents IW, which partially cancel the current flow in the center and reinforce it near the skin.

    For example, in copper at 60 Hz, the skin depth is about 8.5 mm. At higher frequencies—such as in radio or high-frequency switching circuits—it becomes much smaller, sometimes only a fraction of a millimetre.

    Why It Matters

    Because AC current tends to crowd toward the surface, less of the conductor is effectively carrying current. The result is a smaller conducting area, resulting in greater resistance than with direct current (DC).

    At low frequencies, this effect is minimal; however, as the frequency rises, engineers must account for the skin effect when designing busbars, transformer windings, RF components, and high-frequency power systems to ensure optimal efficiency and thermal performance.

    Skin effect: skin depth decreases with increasing frequency.

    Balanced vs Unbalanced — and Why It Matters

    One of the biggest conceptual takeaways was the difference between balanced and unbalanced lines.

    • Balanced lines — like ladder line or open-wire feeders — carry equal and opposite currents, cancelling their electromagnetic fields and minimizing radiation from the line itself. They’re remarkably efficient and forgiving of mismatch losses, but they demand careful installation: constant spacing, no nearby metal, and protection from rain and ice.
    • Unbalanced lines, primarily coaxial cables, put one conductor at ground potential and carry RF on the inner conductor. They’re rugged, weather-resistant, and far easier to route through walls and towers — which is why almost every modern ham shack uses them. The trade-off is higher loss, especially at VHF and UHF, and the ever-present danger of water ingress if you neglect proper sealing.

    Coax Choices and Connectors

    We also looked at the “alphabet soup” of coax cables — RG-58, RG-8, RG-213, LMR-400, and others. The takeaway is that cable choice is all about loss versus flexibility. Smaller, flexible cables like RG-58 are fine for short HF runs, but not for long VHF or UHF feeds. Heavier cables or low-loss hardline types deliver more power with less attenuation, but are expensive and stiff.

    Even connectors matter. The classic PL-259/SO-239 “UHF” connector still dominates HF rigs, though it’s really only suited for the lower frequencies. Higher-frequency work calls for N-type or SMA connectors, each designed to maintain consistent impedance at GHz ranges.

    Connector TypePlug (Male)Jack (Female)
    Type NType N male plug connector(pin with threads inside)Type N female jack connector(socket with threads outside)
    UHF (PL259)UHF (PL259) male plug connector(pin with threads inside)UHF (PL259) female jack connector(socket with threads outside)
    TNCTNC male plug connector(pin with threads inside)TNC female jack connector(socket with threads outside)
    Reverse Polarity TNC (RPTNC)RPTNC male plug connector(socket with threads inside)RPTNC female jack connector (pin with threads outside)
    BNCBNC male plug connector(pin with threads inside)BNC female jack connector(socket with threads outside)
    SMASMA male plug connector(pin with threads inside)SMA female jack connector(socket with threads outside)
    Reverse Polarity SMA (RPSMA)RPSMA male plug connector(socket with threads inside)RPSMA female jack connector (pin with threads outside)

    The Role of the Balun

    Balanced antennas like dipoles don’t always play nicely with unbalanced coax, and that’s where baluns (balanced-to-unbalanced transformers) come in. A simple choke balun — just a coil of coax at the feedpoint — can stop unwanted current from creeping down the outside of your shield. More sophisticated transformer baluns use ferrite cores to match impedances and isolate circuits. It’s a brilliant bit of engineering simplicity that can make or break an antenna system.

    When the Waves Stand Still

    Finally, we explored VSWR — Voltage Standing Wave Ratio. In theory, a perfect match between radio, cable, and antenna gives a 1:1 ratio. In reality, a little reflection is normal — a VSWR of 2:1 is fine, but 5:1 means you’ve got work to do. Watching those peaks and valleys on a scope or analyzer really drives home how reflections eat power and distort performance.

    Looking Ahead

    This chapter was a solid reminder that the magic of radio isn’t just in the airwaves — it’s in the copper, dielectric, and geometry of the cables that connect everything together. Transmission lines are the quiet heroes of every ham station: invisible when they work right, painfully obvious when they don’t.

    Sources

    [1] A. Penney, ‘Transmission Lines’, Online, Oct. 23, 2025.

    [2] S. Arar, ‘RF Design Basics—Introduction to Transmission Lines’, All About Circuits. Accessed: Oct. 19, 2025. [Online]. Available: https://www.allaboutcircuits.com/technical-articles/basic-concepts-in-rf-design-introduction-to-transmission-lines/

    [3] ‘What Is the Skin Effect?’

  • Step-by-Step—Class 6

    Step-by-Step—Class 6

    1. Step by step – 1st Class
    2. Step-by-Step – 2nd Class
    3. Amateur Radio Codes of Conduct
    4. Step-by-Step – 3rd Class
    5. Step-by-Step – Class 4a
    6. Step-by-Step – Classes 4b & 4c
    7. Step-by-Step—Class 5
    8. Step-by-Step—Class 6
    9. Step-by-Step—Class 7
    10. Step-by-Step—Class 8a
    11. Step-by-Step—Class 8b
    12. Step-by-Step—Class 9
    13. Step-by-Step—Class 10
    14. Step-by-step—Class 11
    15. A Modern Code of Conduct and Ethics for Amateur Radio
    16. Step-by-step—Class 12
    17. Step-by-step—Class 13
    18. Step-by-step—Class 14
    19. Step-by-step—Class 15
    20. Step-by-step—Class 16
    21. Step-by-step—Class 17
    22. Reflection: My Amateur Radio Journey So Far
    23. Authorized to Transmit

    Riding the Waves: Reflections on Radio Propagation

    This week’s class on radio-wave propagation took me right back to my roots. It’s hard not to smile when I see diagrams of skywaves, ground waves, and skip zones — things I first learned about nearly forty years ago at Sheridan College, when we were still using analog oscilloscopes and scientific calculators. Back then, I was an electronics engineering technology student just getting ready to start my career, and the idea that invisible waves could circle the globe felt almost magical.

    Now, as I sit in class once again — decades later, after a long career in electronics and electrical control system design — I see those same principles through a different lens. What once seemed like mysterious phenomena now feel like old friends whose habits I know well. The theory hasn’t changed, even though the tools and applications have evolved beyond what I could have imagined in 1985.

    From Spark-Gap to Skywave

    The story of radio propagation is as much about curiosity as it is about science. When Guglielmo Marconi proved in 1901 that a wireless signal could cross the Atlantic, he didn’t know why it worked — only that it did. He thought the waves were following the Earth’s curve, but in reality, they were bouncing off the ionosphere — a discovery that wouldn’t be fully understood for decades.

    That experiment, conducted from Signal Hill in St. John’s, Newfoundland, still captures my imagination. It’s a reminder of how experimentation often leads the theory, and how the physics that govern our communication systems today are the same ones that guided those first transatlantic dots and dashes of Morse code.

    The Ionosphere: A Living Mirror

    Of all the layers of the atmosphere, the ionosphere remains the most fascinating. The D, E, and F layers — invisible, dynamic, and ever-changing — are what make global communication possible.

    A schematic cross-section of Earth’s atmosphere and ionosphere: The left side shows the Earth at the bottom with concentric transparent bands representing atmospheric layers (troposphere near the surface, then stratosphere, mesosphere, thermosphere, and exosphere at the top). On the right side, a simplified graph overlays region boundaries labelled D, E, and F, with dashed lines indicating locations within the thermosphere and upper mesosphere. Temperature and/or density axes are implied, indicating an increase in altitude upward to approximately 10,000 km. The graphic emphasizes that the ionosphere (regions D → E → F) lies within the thermosphere/upper atmosphere.
    The Ionosphere (Thermosphere) is part of Earth’s Atmosphere. The Thermosphere is characterized by very high temperatures ranging from 550 to over 1300 degrees Kelvin due to the solar EUV. [1]
    image: qsl.net
    A stylized diagram showing the ionospheric regions over the Earth’s surface during day and night: On the left side (“day”), three colored horizontal bands labelled D (~60-90 km), E (~90-150 km), and F (~150-≈600 km) ascend upward from the Earth’s surface. On the right side (“night”), only the F region remains prominent (labelled “F”), while the D and E bands are faint or absent. Arrows indicate solar-ionization (incoming from the sun-lit side) and recombination (on the night side). The figure emphasizes how free-electron density varies by region and time of day.
    Ionospheric regions illustration [1]
    image: qsl.net

    During the day, the D layer absorbs low-frequency signals, muting AM stations that roar back to life at sunset. The higher F layers, split into F1 and F2 in daylight, refract HF signals over thousands of kilometres, bending them back toward Earth like a mirror made of charged particles. [1], [3]

    A schematic diagram showing three distinct radio-wave propagation paths between a transmitter and a distant receiver: • On the left, a straight line labelled “Line-of-Sight (LOS)” travels directly from the transmitting antenna to the receiving antenna above the Earth’s surface, implying a direct path without bending. • In the middle, a path labelled “Ground Wave / Surface Wave” follows along the contour of the Earth’s surface (curving slightly), indicating a wave that hugs the ground and travels beyond the visual horizon. • On the right, a curved upward-then-downward path labelled “Sky-Wave / Ionospheric Refraction” leaves the transmitter at a low angle, arcs upward to the ionosphere, bends (or is refracted) back toward the Earth, and lands at the receiver far beyond the horizon. In the space between the ground-wave and sky-wave paths is the “skip zone” (a region of no reception) indicated by shading or dashed lines. The diagram is set against a stylized cross-section of the Earth and atmosphere, with altitude increasing upward and horizontal distance along the bottom.
    Ionospheric reflections
    image: qsl.net [3]

    Even after years of working with EMI and high-frequency noise in control systems, it still amazes me how the same physics in a factory floor’s PLC cabinet also govern how a signal from halfway around the world reaches a simple dipole antenna in my backyard.

    Of Sunspots, Solar Flux, and the Unseen Weather Above

    As engineers, we tend to think of “weather” as something that affects reliability through temperature or humidity. But this week’s class reminded me that space weather plays an equally critical role. Solar flares, coronal mass ejections, and sunspots — the restless activity of our nearest star — shape the ionosphere daily [2], [5].

    The Dominion Radio Astrophysical Observatory in Penticton, BC, has been measuring the Sun’s radio emissions at 2800 MHz since the 1940s, producing the Solar Flux Index we still rely on. Seeing that connection between a Canadian observatory, solar physics, and real-world radio performance renewed my appreciation for how deeply our communications depend on phenomena far beyond our control.

    Skip Zones, Fading, and the Fragile Nature of Connection

    In my work over the years, I’ve seen signal dropouts caused by everything from ground loops to induction noise, but ionospheric fading has a kind of poetry to it. The way signals strengthen and vanish as the ionosphere shifts with time and sunlight reminds me that all communication — whether through copper, fibre, or free space — is ultimately about timing and conditions.

    Overview of HF Propagation Modes
    image: qsl.net [3]

    Skip zones, backscatter, and multipath effects are more than textbook curiosities; they’re metaphors for the real-world challenge of designing systems that perform reliably despite an unpredictable environment. Our ability to predict, compensate for, and even exploit those effects is a testament to a century of accumulated engineering wisdom.

    NVIS and the Modern Relevance of Propagation

    Near Vertical Incidence Skywave (NVIS) propagation especially caught my attention. It’s used today for short-range HF communication, where terrain or disasters might block line-of-sight signals. I couldn’t help but think how that same principle could apply to robust emergency communications or even industrial networks in remote regions.

    Approximate NVIS Signal Range [4]
    image: hamradiooutsidethebox.ca

    NVIS signals are propagated at a high elevation (greater than 60°). They are reflected down from the ionosphere (principally the F2 layer) over an area of a few hundred kilometres from the source. [4]

    Using trigonometric calculations, we can estimate the NVIS coverage to be about 350 kilometres. Because the diagram represents a two-dimensional view, it’s essential to understand that this range extends equally in all directions from the transmitting station. In other words, if we imagine a circle centred on the transmitter with a radius of 350 kilometres, any receiver positioned within that circle should be able to detect the NVIS signal.

    Despite all our modern connectivity, there’s still a place for understanding how nature itself moves information from one point to another.

    Closing Thoughts

    For me, studying propagation again isn’t about relearning the formulas — it’s about rediscovering the elegance behind them. The same electromagnetic principles that may have carried Marconi’s letter “S” across the Atlantic in 1901 still underpin the wireless links in a factory, the telemetry in a wind farm, or the Wi-Fi in our homes.

    After four decades in the field, it’s humbling to be reminded that no matter how advanced our technology becomes, we’re still riding the same waves — reflections from the same sky, governed by the same physics, and inspired by the same human drive to connect across distance.

    References

    [1] D. Tal, “Region vs. Layer: Earth’s Atmosphere and Ionosphere”. Accessed: Oct. 10, 2025. [Online]. Available: https://www.qsl.net/4x4xm/Region-vs-Layer-Earth’s-Atmosphere-and-Ionosphere.htm

    [2] ‘Space Weather’, spaceweather.com. Accessed: Oct. 10, 2025. [Online]. Available: https://www.spaceweather.com

    [3] D. Tal, ‘Skywave Propagation Basics’, Understanding HF Skywave Propagation. Accessed: Oct. 21, 2025. [Online]. Available: https://www.qsl.net/4x4xm/HF-Propagation.htm

    [4] John VA3KOT, ‘The NVIS Illusion’, Ham Radio Outside the Box. Accessed: Oct. 21, 2025. [Online]. Available: https://hamradiooutsidethebox.ca/2023/06/19/the-nvis-illusion/

    [5] N. R. C. Government of Canada, ‘Current regional magnetic conditions’. Accessed: Oct. 21, 2025. [Online]. Available: https://www.spaceweather.gc.ca/forecast-prevision/short-court/regional/sr-1-en.php?region=ott&mapname=east_n_america

  • Step-by-Step—Class 5

    Step-by-Step—Class 5

    1. Step by step – 1st Class
    2. Step-by-Step – 2nd Class
    3. Amateur Radio Codes of Conduct
    4. Step-by-Step – 3rd Class
    5. Step-by-Step – Class 4a
    6. Step-by-Step – Classes 4b & 4c
    7. Step-by-Step—Class 5
    8. Step-by-Step—Class 6
    9. Step-by-Step—Class 7
    10. Step-by-Step—Class 8a
    11. Step-by-Step—Class 8b
    12. Step-by-Step—Class 9
    13. Step-by-Step—Class 10
    14. Step-by-step—Class 11
    15. A Modern Code of Conduct and Ethics for Amateur Radio
    16. Step-by-step—Class 12
    17. Step-by-step—Class 13
    18. Step-by-step—Class 14
    19. Step-by-step—Class 15
    20. Step-by-step—Class 16
    21. Step-by-step—Class 17
    22. Reflection: My Amateur Radio Journey So Far
    23. Authorized to Transmit

    From Sparks to Software: Reflections on Waves, Wavelengths, and the Spirit of Radio

    Every so often, a class reminds me that the fundamentals never really change. This week’s topic — Waves, Wavelength, Frequency, and Bands — was a trip back in time for me. As someone who trained as an electronics engineering technologist in the 1980s, this material feels like old territory. Yet, revisiting it in today’s context, with modern software-defined radios (SDRs) and digital signal processing, highlights just how enduring these basic principles are.

    The Timeless Language of Waves

    The lecture opened with the essentials: amplitude, wavelength, and frequency — the vocabulary of every waveform, whether it’s a sound wave in air or a radio wave racing through space. Back then, we learned these on oscilloscopes with green phosphor traces, adjusting time bases and triggering circuits to freeze those elegant sine waves in time. Today, the same principles remain, but the scopes are digital, and the waves are simulated, captured, and analyzed by software.

    A diagram of the electromagnetic spectrum, showing various properties across the range of frequencies and wavelengths.
    Image: Inductiveload, Wikimedia Commons

    What hasn’t changed is the relationship between wavelength and frequency — the beautiful simplicity of ( c = f \λ ), where the speed of light ties them together. It’s still the same 300 × 106 metres per second in free space, as it was for Heinrich Hertz when he first proved Maxwell’s equations right. The numbers might scale from kilohertz to gigahertz now, but the physics hasn’t changed a bit.

    Band NameAbbr.ITU bandFrequencyWavelength
    Extremely low frequencyELF13–30 Hz100,000–10,000 km
    Super low frequencySLF230–300 Hz10,000–1,000 km
    Ultra low frequencyULF3300–3,000 Hz1,000–100 km
    Very low frequencyVLF43–30 kHz100–10 km
    Low frequencyLF530–300 kHz10–1 km
    Medium frequencyMF6300–3,000 kHz1,000–100 m
    High frequencyHF73–30 MHz100–10 m
    Very high frequencyVHF830–300 MHz10–1 m
    Ultra high frequencyUHF9300–3,000 MHz100–10 cm
    Super high frequencySHF103–30 GHz10–1 cm
    Extremely high frequencyEHF1130–300 GHz10–1 mm
    Terahertz or tremendously high frequencyTHF12300–3,000 GHz1–0.1 mm
    Band names
    [13]

    A Short History of Long Waves

    Thinking about waves and bands always takes me back to the early history of radio — to the days of spark-gap transmitters, longwave Morse signals, and men like Hertz, Marconi, and Fessenden. Those pioneers were dealing with kilohertz frequencies, with antennas and capacitors the size of ships, yet they were manipulating the same invisible medium we use today.

    Marconi’s Antenna Towers, Glace Bay, Nova Scotia. The four 200-foot wooden latticework towers shown supported an inverted pyramid of antenna wires not visible in the photo.
    Marconi Antenna Array Structure, 1907

    I’m pretty sure my neighbours would be unhappy with me if I built an antenna array that resembled Marconi’s Glace Bay installation!

    The circuit diagram of the December 1901 Poldhu transmitter in J.A. Fleming’s handwriting.

    By 1907, the Marconi station at Glace Bay, Nova Scotia, was operating on remarkably low frequencies for its time — around 70 kHz. That range was chosen for the transatlantic service linking Glace Bay with Clifden, Ireland, inaugurated in October 1907.

    Earlier experiments at the site had been conducted on higher frequencies — roughly 182 kHz in 1902 and 272 kHz for some later trials — but Marconi’s engineers soon discovered that lower frequencies provided far greater reliability over long distances. By 1907, they had moved down to around 70 kHz, and eventually as low as 45 kHz.

    These very long wavelengths (VLF) proved ideal for transatlantic work. The signals could travel enormous distances, reflecting between the Earth and the ionosphere, and remained stable both day and night — something that higher frequencies of the day couldn’t achieve. Considering the limits of early transmitters and receivers, this was an extraordinary technical accomplishment and a milestone in the development of reliable global communication.

    First Transatlantic Radio Service, October 17, 1907

    In the photo above, Marconi Operator L.R. Johnstone is shown transmitting the first official messages of the commercial wireless telegraph service from Marconi Towers, near Glace Bay, Nova Scotia, to Clifden, Ireland, on October 17, 1907. Ten thousand words were exchanged between the stations on the first day of operation.

    Marconi rotary spark discharger
    image: Cape Breton Wireless Heritage Society

    The rotary spark discharger was the heart of the spark transmitter at Marconi Towers. In the upper-right background, the three large ring-shaped loops are the three turns of the antenna transformer’s primary coil, which fed the spark’s electrical energy into the high-mounted antenna.

    Historical Photo of Marconi Wireless Site and Towers in Glace Bay, Nova Scotia, Canada.
    See page for author, Public domain, via Wikimedia Commons.
    Coal-fired boilers in the power house at Marconi Towers produced steam for the main steam engine and alternator.
    image: Cape Breton Wireless Heritage Society

    At the Marconi station in Glace Bay, Nova Scotia, six steam boilers powered dynamos that generated the 15 kV power supply, which charged a capacitor composed of 288 metal sheets, each measuring 60 feet by 20 feet, separated by approximately 6 inches. The sheets were suspended from rafters at the top of the building and hung vertically almost to ground level. This capacitor (or “condenser,” as it was initially called) occupied most of the 160-foot-long transmitter building. As a result, the building became known as the condenser building.

    Main operating building of Marconi Wireless Station, ca. 1912.
    Collection of Port Morien Station, ca. 1912 / Collection de la station de Port Morien, vers 1912.

    This extensive array of plates offered only 1.7 microfarads of capacitance, with a voltage rating of 15 kilovolts. An “air-insulated” design was selected over a more compact glass dielectric design because it was relatively trouble-free and easy to build using locally available materials. If a draft caused the plates to shift and short-circuit, the “spot-welded” plates could be knocked apart with a sledgehammer.

    Marconi’s Condenser (Capacitor) at Glace Bay, Nova Scotia

    One story that sticks in my mind is Weather Station Kurt, a German automatic transmitter secretly placed in Labrador during the Second World War. It operated on 3940 kHz — smack in what we now think of as the amateur 80 m band — sending weather reports back to Germany every few hours. Even in wartime, radio’s reach was both strategic and scientific, and its physics — the propagation of electromagnetic waves through atmosphere and ionosphere — governed everything.

    From Resonant Circuits to Software Radios

    Interaction between Capacitive and Inductive reactance and the resonance point — Slide by Al Penny VO1NO

    When I first learned about LC circuits, we tuned them with physical coils and capacitors, feeling resonance through the sound in a speaker or the flicker on a meter. The “bands” we talked about then — HF, VHF, UHF — were as much about practical limitations as they were about regulation. Antenna length, wavelength, and atmospheric reflection all dictated what was possible.

    Today, when I look at a modern software-defined radio (SDR), I find it astonishing to think that an entire superheterodyne receiver now fits in a USB drive. Instead of a coil and a capacitor, we use algorithms to shift and filter signals in code. But the foundation — waves, frequencies, and harmonics — is the same. Whether it’s a spark-gap transmitter, a vacuum-tube superhet, or a LimeSDR, every one of them lives by the same electromagnetic laws.

    Why It Still Matters

    There’s a certain poetry in knowing that a 7 MHz signal — the classic 40 m amateur band — still bounces off the ionosphere just as it did when I first listened to shortwave broadcasts as a teenager. The gear has changed; the spectrum hasn’t. Even in a world dominated by Wi-Fi, Bluetooth, and cellular links operating in gigahertz ranges, it all still comes down to waves oscillating in time and space.

    So while the students around me might be seeing this material for the first time, I find myself smiling at how familiar it feels. The math is old, the physics immutable, and yet the applications keep evolving. From sparks to software, from the hiss of AM static to the crisp digital decoding of an SDR waterfall, it’s all the same story — one wave at a time.

    Looking Ahead

    As the course continues, I’m looking forward to diving deeper into how these timeless wave fundamentals shape the communication technologies we rely on every day. Understanding them through both the lens of experience and modern tools like SDRs bridges the gap between the analog world in which I first learned and the digital systems that define today’s engineering practice. It’s a reminder that while technology evolves, the language of physics remains beautifully consistent — and that makes every new concept feel like an old friend revisited.

    References

    [1] Marconi – Krause House Info-Research Solutions

    [2] On this day in 1907

    [3] List of Marconi wireless stations

    [4] Guglielmo Marconi

    [5] List of Marconi wireless stations – Wikiwand

    [6] Frequency Spectrum Management Overview

    [7] Radio’s First Message – Fessenden and Marconi

    [8] An Historical and Technological Survey

    [9] ULTRA TCS – Canadian Marconi History

    [10] VE1DEW – Callsign Lookup by QRZ Ham Radio

    [11] M. Rosano, “Throwback Thursday: Nazi weather station in Labrador”, Canadian Geographic. 2015. Available: https://canadiangeographic.ca/articles/throwback-thursday-nazi-weather-station-in-labrador/ [Accessed: 2025-10-16]

    [12] ‘The First Transatlantic Wireless Stations in Cape Breton’, Cape Breton Wireless Heritage Society. Accessed: Oct. 13, 2025. [Online]. Available: http://www.cbwireless.ednet.ns.ca/cbwirelessp3.html

    [13] Rajiv, ‘Radio Frequency Bands’, RF Page. Accessed: Dec. 07, 2025. [Online]. Available: https://www.rfpage.com/what-are-radio-frequency-bands-and-its-uses/

  • Step-by-Step – Classes 4b & 4c

    Step-by-Step – Classes 4b & 4c

    1. Step by step – 1st Class
    2. Step-by-Step – 2nd Class
    3. Amateur Radio Codes of Conduct
    4. Step-by-Step – 3rd Class
    5. Step-by-Step – Class 4a
    6. Step-by-Step – Classes 4b & 4c
    7. Step-by-Step—Class 5
    8. Step-by-Step—Class 6
    9. Step-by-Step—Class 7
    10. Step-by-Step—Class 8a
    11. Step-by-Step—Class 8b
    12. Step-by-Step—Class 9
    13. Step-by-Step—Class 10
    14. Step-by-step—Class 11
    15. A Modern Code of Conduct and Ethics for Amateur Radio
    16. Step-by-step—Class 12
    17. Step-by-step—Class 13
    18. Step-by-step—Class 14
    19. Step-by-step—Class 15
    20. Step-by-step—Class 16
    21. Step-by-step—Class 17
    22. Reflection: My Amateur Radio Journey So Far
    23. Authorized to Transmit

    From Capacitance to Resonance: Revisiting the Fundamentals

    Over the past couple of classes, we’ve been exploring two interconnected concepts in electronics: capacitance and resonance. For me, these aren’t new ideas—I first studied them at Sheridan College back in the 1980s, when oscilloscopes still had CRTs and breadboards came with point-to-point wiring. Even so, it has been rewarding to revisit these foundational topics with a fresh perspective and a few more decades of practical experience under my belt.

    Understanding Capacitance

    Capacitance is one of those elegant concepts that forms the backbone of modern electronics. A capacitor—two conductive plates separated by an insulating dielectric—resists changes in voltage by storing and releasing energy. It’s such a simple structure, but its impact on everything from timing circuits to power supplies can’t be overstated.

    Revisiting the theory reminded me just how differently capacitors behave in DC versus AC circuits. In DC, a capacitor charges up to the supply voltage and then effectively becomes an open circuit. In AC, though, the constantly changing voltage makes it look as though current flows straight through—even though electrons never actually cross the dielectric. This behaviour gives rise to capacitive reactance (XC), which decreases as frequency increases. That’s why capacitors block DC but pass high-frequency signals, making them indispensable in filters and coupling circuits.

    The unit of capacitance, the farad, is far too large for most real-world applications, which is why we use microfarads, nanofarads, and picofarads instead. Plate area, spacing, and dielectric material all shape a capacitor’s behaviour—details I once learned in a classroom, but now appreciate in a far deeper way after years of working with safety systems and control circuits.

    Revisiting Resonance

    Next came resonance—another familiar but fascinating topic. An inductor resists changes in current through its magnetic field, while a capacitor resists changes in voltage through its electric field. Put them together and, under the right conditions, they exchange energy back and forth in a kind of electrical echo.

    Resonance happens when the inductive reactance (XL) and capacitive reactance (XC) are equal and cancel each other out. At that frequency, the circuit oscillates like a perfectly tuned pendulum, trading energy between the capacitor’s electric field and the inductor’s magnetic field. That’s the essence of every tuned circuit—from early radio receivers to modern communication filters.

    One example that always comes to mind when talking about resonance is the Tacoma Narrows Bridge collapse of 1940. Although it wasn’t pure electrical resonance—it was aeroelastic flutter—the underlying principle was the same: energy reinforcing itself until a system fails. It’s a dramatic reminder of how resonance, in any form, can be both powerful and destructive if it’s not managed properly.

    Series and Parallel Resonance

    Reviewing series and parallel RLC circuits brought back memories of long lab sessions and breadboards filled with coils and capacitors. In a series circuit, resonance minimizes impedance, leaving only the resistance to limit current. In a parallel circuit, it does the opposite—impedance rises to a maximum.

    Those two behaviours form the basis of almost every practical filter: low-pass, high-pass, band-pass, or notch. Seeing the relationships between theory and application again reminded me why I fell in love with electronics in the first place. There’s something deeply satisfying about watching a sine wave sharpen or flatten on a scope exactly as the equations predict.

    The Quality Factor (Q) and Real-World Radios

    We also revisited the Q factor, which describes how “sharp” or selective a resonant circuit is. High-Q circuits have narrow bandwidth and greater selectivity, while low-Q circuits are broader and less discriminating.

    I built my first crystal radio as a preteen, so it was fun to see it come up again. With its single tuned circuit and diode detector, the crystal set has a very low Q—but it works. With nothing more than a coil of wire, a bit of crystal (or even a sugar cube and a sewing needle, if you’re improvising), and a pair of headphones, you can literally pull voices and music out of the air. Even now, I still find that magical.

    My Takeaway

    Revisiting capacitance and resonance after four decades reminded me how enduring the fundamentals really are. These aren’t just abstract properties—they’re the building blocks of everything from radios to robotics. Capacitors don’t merely “store charge”; they make stable, responsive, and selective systems possible. Resonant circuits don’t just cancel reactances; they allow us to shape and control the signals that carry our modern world.

    Coming back to these topics, I find myself both nostalgic and appreciative. The equations haven’t changed, but my understanding of their importance has deepened. It’s a reminder that no matter how advanced technology becomes, it all still rests on the same elegant principles we learned with coils, capacitors, and curiosity.

  • Step-by-Step – Class 4a

    Step-by-Step – Class 4a

    1. Step by step – 1st Class
    2. Step-by-Step – 2nd Class
    3. Amateur Radio Codes of Conduct
    4. Step-by-Step – 3rd Class
    5. Step-by-Step – Class 4a
    6. Step-by-Step – Classes 4b & 4c
    7. Step-by-Step—Class 5
    8. Step-by-Step—Class 6
    9. Step-by-Step—Class 7
    10. Step-by-Step—Class 8a
    11. Step-by-Step—Class 8b
    12. Step-by-Step—Class 9
    13. Step-by-Step—Class 10
    14. Step-by-step—Class 11
    15. A Modern Code of Conduct and Ethics for Amateur Radio
    16. Step-by-step—Class 12
    17. Step-by-step—Class 13
    18. Step-by-step—Class 14
    19. Step-by-step—Class 15
    20. Step-by-step—Class 16
    21. Step-by-step—Class 17
    22. Reflection: My Amateur Radio Journey So Far
    23. Authorized to Transmit

    Sunday the 28th was our fourth class. We cover the basics of magnetism and inductance.

    Inductance: From High School Chalkboards to Everyday Engineering

    When I first studied inductance back in high school in the 1980s, it all felt a bit abstract. We were told that electricity and magnetism were linked in curious ways, that a simple wire could resist changes in current, and that this mysterious thing called “back EMF” always seemed to push back against whatever we tried to do. At the time, it felt like a trick of the math more than a tangible reality.

    Fast forward to today, and I see those same fundamentals in every transformer, motor, and circuit I encounter. The equations on the chalkboard have become the backbone of modern engineering practice.

    The Basics Haven’t Changed

    Inductance, at its core, is about resistance to change. Any conductor carrying current produces a magnetic field, and when that current changes, the magnetic field changes with it. Faraday showed us that a changing magnetic field induces a voltage, and Lenz’s law tells us that voltage will always oppose the change that created it. That’s why a conductor, whether straight or wound into a coil, pushes back against changes in current flow.

    In a classroom, this was demonstrated with the right-hand rule and magnetic field lines circling a wire. Winding that wire into a coil concentrated the flux, boosting its ability to oppose current changes. Back then it was a curious property. Today, I see it as nature’s built-in safety feature.

    Inductors in Action

    This week’s presentation walked through inductance in both DC and AC circuits. With DC, inductance delays the rise of current until the magnetic field stabilizes. With AC, the story is more dynamic: the magnetic field is always changing, always inducing a voltage that resists the flow. The result is what we call inductive reactance—an opposition that grows with frequency.

    This dual behaviour explains why inductors pass DC easily but can choke out higher-frequency signals. It’s the same principle that makes them indispensable in filters, power supplies, and countless control applications.

    From Inductors to Transformers

    Once coils are involved, it’s a short step to transformers. Here, changing currents in one coil induce voltages in another, enabling us to step voltages up or down, match impedances, or isolate circuits entirely.

    The elegance of the turns ratio—primary to secondary—never ceases to impress me. Whether it’s a massive utility transformer or a tiny toroidal inductor on a circuit board, the same rules apply: ratios matter, losses must be managed, and efficiency is king. Even after all these years, I find the beauty of this simple, reliable relationship remarkable.

    Enduring Lessons

    Looking back, what strikes me most is how little these fundamentals have changed. The names—Faraday, Henry, Lenz—still echo through the equations, but the applications have multiplied beyond what I could have imagined as a teenager.

    In high school, inductance was just another physics unit to get through before exams. Today, I see it as a quiet constant in my daily work—woven into motors, relays, solenoids, and transformers, underpinning so much of the technology we depend on.

    The fundamentals of inductance have aged better than we have: steady, dependable, and still as sharp as ever.