Principles of Amateur Radio

This is a comprehensive outline of the basic certificate licensing course presented by the Bulkley Valley Amateur Radio Society in the Spring of 2019.

Questions may be directed by email to:

This webpage is a hierarchical document consisting of many small “cards”. It is too meandering to usefully read from beginning to end, so I recommend proceeding roughly top-left to bottom-right, as time and interest warrant.

Read cards left to right, to the level of detail desired, and then top to bottom. Use keyboard, mouse, or touch to navigate.

This document is a work in progress. It is available on the web at:

A printable version of this page may be useful if the default interactive presentation is incompatible with your web browser.

Quick Links
Listen live to Smithers amateur scanner — presently down :(

A convenient web-SDR for casual listening (see more far below)

For distraction, listen to local community broadcast station CICK 93.9 MHz (listen live)

Exam Outline, Question Bank, Study Aids

This section includes links to the exam question bank, as well as other study aids provided by other courses.

The Exam

The Basic Qualification exam a is two-hour, closed-book, 100-question multiple-choice test. The exam requires a calculator, ideally a scientific calculator. (Smartphone calculators not permitted.)

A passing grade is 70%. Achieving 80% or greater grants additional “HF” operating privileges.

Each question pertains to one of a hundred different topics, organized into eight sections as follows.

(from RIC-3, see also)

Regulations and Policies - 001
(25 Questions)


nature of amateur communications

Operating Privileges
Basically, the topics pertaining to operating privileges boil down to:

legal operation

playing nice with others

international stuff


Operating and Procedures - 002
(9 questions)

Basic Electronics and Theory - 005
(13 questions)

Basic electricity (all covered in class 2&3)

Electromagnetism (class 4)


Feedlines and Antenna Systems - 006
(13 questions)

feedlines (class 5)

antennas (class 5, beginning)

Radio Wave Propagation - 007
(8 questions)

types of propagation &
the ionosphere

Types of Waves

The Sun and the Ionosphere


practical considerations

(Active) Circuit Components - 004
(6 questions)

Interference and Suppression - 008
(5 questions)

Station Assembly, Practice and Safety - 003
(21 questions)


block diagrams

(see also block diagram study resources)

pg 11-11

digital stuff (also some block diagrams)

power stuff


The Campbell River Radio Club has a guide called Hamwork that gives a condensed treatment of the entire exam. They also provide a Windows computer program called “ExHaminer” for practice exams.

The entire question bank is available online, in various forms.

The government exam site has some resources too, including

Studying and Writing the Exam

Eliminate one or two nonsensical answers

Focus on topics that are extensively covered (lots of questions and variations)

Memorize early what must be memorized (due to the absence of clear patterns and underlying structure): band limits, bandwidth limits, Q-codes, and the phonetic alphabet.

Other Courses

There are a few other freely-available online courses.

Emergency Communications of Ontario has a course. It has some pretty good slides.

The Yukon amateur radio society offers a very comprehensive course, broken down by topic, with lots of supplemental resources, and chapter references to the Coax study guide.

For a different treatment, the Delta Amateur Radio club also has a similar page of resources.

Advanced Qualification

The Advanced Qualification Exam is a fifty-question exam, again with a 70% pass rate and the same restrictions.

Becoming an Examiner

Requires Basic, Advanced, and Morse Code qualifications. See here.

Course Content, Notes, Homework, etc.

This section includes the material covered in each class.

Class 1: Registration, Introduction, Familiarization

Background and Motivation

Amateur radio makes for a stronger community. Therefore, it is in everyone’s interest that there are more and better amateur operators in our community, and that is why we are putting on a course.

Here is a university-level course on radio, including amateur radio: Experiential course in Ham Radio: Technics, Ecology and Culture of Amateur Radio in the 21st Century

There are lots of ways to teach. There are lots of ways to learn.

The intent is to facilitate a learning experience that is different from typical ham radio courses, in that it addresses (gently) shortcomings in the ham radio community, and prepares operators for the world to come.

What are the shortcomings?

What might be the world to come?

Well, the demographics are problematic. Depending on how you look at it, it’s either a bunch of old white men who talk too much, and a bunch of younger computer nerds who don’t like to talk much.

The world to come is… Well, let’s just say that a lot of ham radio people are preppers, and a lot of preppers want ham radio licenses.

Also, learning is not just about passing exams. Learning happens regardless of the outcome of an exam. Passing the exam does not demonstrate mastery of the content. Life is not about accumulating prestige and credentials. My intent is to help people learn, build relationships, and contribute to the community.

Although I very much enjoy it, I am not here just to lecture; we are here to have a discussion and facilitate an experience. If you want to watch a lecture, go on YouTube. They’re much better! (Narrator: He mostly lectured.)

Why am I harping on the fundametals so much? Because technology is not about applications.

I’ll say that again: Technology is not about applications. Applications are a side-effect. If all a person understands is the applications, then they won’t understand why they’re doing what they’re doing, and eventually, they’ll just be helpless.

The thing about applications is that you can understand them in terms of what they do, and not understand why… The thing about fundamentals is that it’s all about understanding why.

If you only understand something in terms of applications without understanding the fundamentals, then it’s the machine that’s building you, and not the other way around.

Why might you be interested in radios?

As I see it, radios are attractive for things that are useful, things that are fun, and for things that are in-between.


Lots of reasons!

useful communications

For example, here are some selections from an article on emergency preparedness.

Radio amateurs get a sweet deal, with effectively free access to many gigahertz of the same radio spectrum that companies pay billions for.

(Note that’s free as in beer, not free as in freedom.)


Then, there’s backup. Take the European HAMNET, for example. That’s a four-thousand-node high speed data network covering a large part of continental Europe and providing full IP connectivity at megabit speeds. It connects to the Internet—-ham radio owns 16 million IPV4 addresses, believe it or not—-but is independent of it, doing its own robust and flexible routing.

If the Internet was to go away, HAMNET would still be running. The same’s true of nearly all ham radio infrastructure. When everything else fails (power, comms, roads), ham radio is still there.

fun communications



Here we get to know the class. Interests, education, background.

Administrivia: Sign-up, distribute books

Demonstrations: What you can do on the radio

In the Bulkley Valley:

Here is an overview of the northern BC repeater network.

Here is a video of somebody operating using morse code


Once upon a time, people commonly built radios out of household parts! Here is an old book that deals with that sort of thing.

Notice how there’s almost no plastic in that book. So insulators, for example, are made of glass and ceramic.

It is still possible to build a radio out of common parts, and we will do this beginning roughly in class two or three.


Start reading the book
Watch some videos
Read some links
Try a quiz

Book: (to be confirmed)


Use the class Access Code to quiz themselves on Chapter 2.

Try as many chapter quizzes as you wish

Make a note of any questions that caused problems, and:


There is a chart that illustrates the spectrum allocations in Canada.

Class 2: Basic Electricity

In the first class, we introduced the concept of the electromagnetic spectrum. So now it’s time to ask a question:

What are radio waves made from?

Some acceptable answers: electricity, magnetism

both are correct

what is electricity made from?

acceptable answers: electrons, electric fields

what is magnetism made from?

magic & miracles

seriously though, we’ll get to magnetics later

so basically, part of the technical content of the course is about electromagnetism, which governs feedlines, antennas, propagation, etc

but it’s too early to talk much about electromagnetism right now

we have to talk about electricity first

two obvious places to start: wall outlets, and batteries

Basic Electricity

Okay, so we established that electricity has something to do with electrons and fields

electricity-water analogy

analogy between voltage and static pressure

analogy between speed and current

analogy between resistance and friction

analogy between power and flow rate



single resistors: Ohm’s law

resistors in parallel

resistors in series

voltage dividers



Read the book, watch some videos



Watch this video on Ohm’s Law, or another like it.

old training video on series and parallel resistors

video on voltage and current in various circuits

ohm’s law practical demo

voltage dividers

Optional: waste lot of time by watching videos from this channel about physics

Class 3: Basic Electricity, part 2.

Basic Electricity

Conclusion of basic electricity part 1:
DC power

theory and definition of electric power

power = current * voltage

units of energy (work-energy theorem)
1 joule = 1 coulomb volt
1 joule = 1 newton meter

units of power
joules / second

units of current
coulomb / second

units of voltage
potential energy per charge

analogy between masses in gravitational field, and charges in an electric field

(advanced) This site talks about electrical-mechanical analogies in quite a lot of detail, far too much detail to be of use really. See also electrical-mechanical-acoustical analogies.

power in a resistor

(nope) demo: current and voltage through a lightbulb

(nope) demo:
power in resistors, using resistance and current measurements (in series and parallel?)

Basic electricity, part 2:
AC power

bicycle-chain model of current in a circuit: AC vs DC

If the current goes back and forth, how does energy get transferred from one end to another? It’s at thing point where we have to stop thinking about current flow in single wires and start thinking about energy transfer in feedlines. This is a useful concept, because that’s what we’re doing with radio systems anyway.

If we have a bicycle chain with a crank on one hand and a flappy paddle on the other, and a person deserving of a few slaps in the path of the flappy paddle, well, then, whether you turn the crank continuously in one direction or whether you turn it back and forth well, then, that person is going to get what’s coming to them either way.

Personal rant: Direct current should be called “unidirectional current” and alternating current should be called “bidirectional current.”

See also better names for things

why 60 Hz? wikipedia

Of interest is the 400 Hz hum of aircraft. Transformer hum video

(See also tone generators)

AC power: peak voltage, RMS voltage, peak current, RMS current

A bit of calculus for the high-school students: How much power is contained in an AC waveform with a given peak votlage compared to a DC waveform at the same voltage?

RMS voltage, current, power
Simply put, the RMS voltage is the DC voltage that would carry an equivalent power.

whistling into a mic and putting the result on a scope: Teasing what’s to come


Watch some videos, read the book.


Everything up to chapter 3, thoroughly.
Chapter 4, skimmed.
Chapter 5, thoroughly.


First, this excellent 50s training video with great animations. Can’t recommend highly enough. As one of the YouTube commenters said, “OLD IS GOLD.”

In the same vein, old training video on electric power (P=EI)

A decent video on RMS voltage and current

Entertaining video on practical differences between DC and AC power: A human perspective

(the part where it starts to get good)

Electroboom on AC vs DC

Elctroboom on volts and amps

For much more detail, this long video on basic electricity, and its long sequel. Both explain the same concepts dealt with in class 3.

Class 4: Electromagnetism, EM Waves, and EM circuit components.

Review up to now

In this class we’re going to talk more about the things that are done with AC signals, using two other components called inductors and capacitors.

Fields and Electromagnetism:
Current in a wire, and consequences thereof

why? Why not. Let’s talk about what’s happening.

electric fields

The concept of a field refers to a tendency of a particle to experience a force that varies with position.

In a gravitational field, the field acts on particles with mass. In an electric field, it acts on particles with electric charge.

The presence of a voltage between two points creates an electric field.

Static charges create static fields.

Steadily moving charges create static fields, and static magnetic fields.

Between static charges and moving charges, the charge must accelerate. Accelerating charges create changing fields.

There’s a comparison to be made here to accelerating mass: Whether moving stopped, you don’t feel any force, but when you accelerate or decelerate, you do.

Anyway, don’t dwell on this; just show the video:
changing field from a charge

DC current in a wire

Steady current in a wire creates a magnetic field.

steady currents are boring

What happens when we go from no current to some current? That is, what happens when the current changes?

illustrations of the following topics

basic and advanced illustrations of field lines


electric field around a wire, which leads to

electric field between two plates (basis of capacitors)

magnetic field around a wire
(basis of inductors)

changing current in a wire

accelerating electrons, consequences thereof

switched dc current, consequences thereof

inductors, an introduction

okay, the spark gap transmitter is based on inductors, so let’s talk about inductors.

an inductor is a component that stores energy in a magnetic field.

the magnetic field is set up as a result of. When the current slows, the magnetic field shrinks. The shrinking magnetic field sets up an electric field, and this electric field causes some current in nearby conductors.

In the case of a lone inductor, this is called back-EMF…

A transformer consists of two inductors side by side. The magnetic fields of both coils affect the current in the other.

In the case of a second inductor next to the first one, the diminishing field in the first coil causes a current to flow in the second.

inductors and fields

The magnetic field in an inductor is due to the current in the coils. The more coils, the more the field you get for a given amount of current.

The quantity that describes “how much” inductor you have is named inductance.

The larger inductor you have, the more energy you can store…. at AC. At steady DC, it looks just like a wire.

More detail: You can think of the magnetic field in an inductor as a ball held aloft by a stream of air.

Actually, a feather is a better analogy; because balls fall quickly when the gust is removed, but feathers fall slowly.

The slow descent of the feather is caused by interaction with the surrounding air; the slow decline of the current is caused by the EMF created when the magnetic field diminishes.


trace of current in spark gap transformer

The current exhibits beats because each side is connected to a resonant circuit.

Energy is being transferred from one side of the transformer to the other, but also on each side of the transformer, energy is sloshing back and forth between components.

inductive reactance

Like the quantity resistance describes the opposition to current flow in a resistor, there is a quantity that describes the opposition to current flow in an inductor. That quantity is called reactance. Specifically, inductive reactance.

The reason we care about reactance, for the purpose of a basic amateur radio course, is because it’s neccesary to calculate a quantity called impedance.

The quantity impedance is important because, as we will see later, it determines how much signal can get from point A to point B.

for now, suffice to say that inductive reactance is dependent on frequency. We can show this with a scope and function generator.

the formula for inductive reactance is […]

the formula for inductance is…

more inductance… more reactance

more inductance…. less (AC) current

inductance tends to block (AC) current

The reason that showing the frequency-dependent behaviour is important is because frequency-dependent behaviour is how filters accept or block certain frequencies, and antennas resonate to preferentially pick certain signals out of the air.

If the scope demos don’t work, we can always show some excellent illustrations of current and voltage in inductors

inductive reactance video

(advanced) detailed page about inductive reactance

capacitors, an introduction

The spark gap transmitter also includes some capacitors, so let’s talk about capacitors.

capacitors and fields

Talking about the field in a capacitor is important when it comes to antennas, so let’s talk about the field in a capacitor.

capacitive reactance

Same as inductors offer an opposition to AC currents, capacitors offer an opposition to AC current too.

capacitance is the quantity that determines “how much” capacitor you have. More capacitance can store more energy…….. at DC.

More capacitance looks more like a wire at AC

more capacitance… more (AC) current

The thing that distinguishes RF AC, that is, signals with high frequencies, from lower frequency line-frequency AC or (zero-frequency) DC is that RF tends to jump gaps.

The gaps are either in-line, that is, in series like capacitors, or in parallel, between pairs of wires, like inductors and transformers.

Electromagnetic waves

The electric and magnetic fields are not static, they are dynamic; that is, changing. They affect one another, causing waves to propagate.

The components that rely on the action of electromagnetic fields are readily adapted into systems that produce electromagnetic fields.

spark-gap transmitter

[dielectric breakdown strength of air]

spark gaps

Air breaks down at about 30 kV/cm,[5] depending on humidity,

nice images of early spark gap transmitters

this page shows the frequency spectrum of an impulse. The sharper the pulse, the broader the spectrum. The spark gap arcs only when once it reaches a certain voltage, and then the current begins to flow very quickly, and quickly stops. see also this page

nature of electromagnetic waves

sound is a wave that propagates in a physical medium

em waves are a means of describing how energy propagates through the pervasive medium of the electric and magnetic fields

These fields can be thought of as separate, but they’re really manifestations of the same thing seen from different directions.

em waves are said to “self-propagate”

animation of waves in a field produced by an accelerating charge

illustration of fields of various shapes

properties of waves

in free space, the waves diminish as they disperse, as a consequence of this self-propagation

impedance, an introduction

The quantity that describes the total opposition to (AC) current is called impedance. The root is the word impede, which means block.

(you’ll notice there are a lot of synonyms like that in EE.)

Signals flow in inverse proportion to the impedance presented.

The reciprocal of impedance is admittance, and if it helps, you can say that signals flow in proportion to admittance.

Impedance can be thought of as being like resistance, but more complicated.

Correctly, resistance is a component of impedance, along with reactance. Impedance is measured in Ohms, and so are resistance and reactance. They can be thought of as impedance in specific directions, like height and width are just length in specific directions.

Like resistance, a circuit with high impedance will have little current flow.

Like resistance, a circuit with low resistance will allow a lot of current to flow.

Impedance includes the effects of resistance and reactance.

The difference between resistance and reactance is that resistance is dissipative — it converts energy into heat, but reactance does not. Reactance sloshes power from one form to another, and pushes back losslessly.

In antennas, the apparent “radiation resistance” dissipates electric power as RF power.

As we saw, reactance varies with frequency, and consequently, impedance varies with frequency.

A circuit may present a low impedance at certain frequencies and admit them readily, but present a high impedance at other frequencies and admit them less readily. The difference between a circuit admitting signals a lot, a little, or not at all results in current flowing a lot, a little, or not at all.

The thing that makes radio interesting is that signals consists of many frequencies at once.

At this point we have to introduce the concept of the frequency domain, and it’s time to start whistling into microphones again.

Extra credit:

general definitions of impedance, for other systems

Impedance is a concept that shows up in any area of physics concerning waves. In transmission lines, impedance is the ratio of voltage to current. In optics, index of refraction plays a role similar to impedance. Mechanical impedance is the ratio of force to velocity.

A general, qualitative answer in David Blackstock’s book Physical Acoustics, on page 46:

Impedance is often described as the ratio of a “push” variable qp (such as voltage or pressure) to a corresponding “flow” variable qf (such as current or particle velocity).

Mechanical impedance is force over velocity and along the cable it is equal to tension over wave speed. The discontinuity may be either an elastic support (with damping properties), or a change unit weight of the cable (bigger cross section) which changes the wave speed.

Mechanical impedance is a measure of how much a structure resists motion when subjected to a harmonic force.

Again, how mush push is required for a given quantity of flow.

Compare to the simpler concept of stiffness, which is force per deflection. The difference is that deflection is static, and motion (or flow) is dynamic; therefore, things like mass and damping matter.







spark gap transmitter

another spark gap transmitter

a wave machine

Lawrence Bragg on EM waves

decent site on EM waves and propagation, with figures


training video on capacitors

Extra credit:

(see also Laithwaite on Magnets)

On capacitors: exploding wire video

more on energy transfer in circuits

Danger! High Voltage

advanced material

current and voltage in RL and RC circuits

ac inductance

ac capacitance

extra credit: we’ve talked about resistors, inductors, capacitors…. but have you heard about memristors?

Class 5: Resonance, Feedlines (ch 7), Antennas (ch 8)



Resonance occurs when there is just as much capacitive reactance as there is inductive reactance.

series resonant circuits pass the resonant frequency and block everything else.

parallel resonant circuits block the resonant frequency

see page 4-20

video: a better description of resonance


The concept of resonance is a bit fuzzy.

in the viciinty of the resonant frequency, the capcitive and uinductive reactance aren’t exactly the same — but they’re close.

Consequently, there is some selection (or filtering) effect — just not as much as at the resonance point. So, the phenomena of resonance has some “width” associated with it.

This width is referred to as bandwidth, and ratio of the bandwidth to some standard baseline is referred to as q-factor

The term q-factor refers to the width of the resonance.

see page 4-22 in the textbook


Basic resonant circuits can be combined to create filters.


A transmission line is a circuit that is specially designed to carry radio-frequency alternating currents.
(Feedlines are also called transmission lines.)

It’s the radio frequency that’s important. Household wiring also carries alternating current, but at low frequencies such that the inductance and capacitance presented is insignificant.

The impedance of most circuits changes with frequency. Transmission lines are special in that they present a constant impedance over a wide range of frequencies.

This animation of a transmission line shows the wiggling electrons in the conductors of a transmission line, and the electric field set up between the bunches and gaps of electrons. You can see how there are waves in the electric field that move from one end to the other.

This excellent bell labs wave machine video clearly explains the wave phenomena in transmission lines.

standing waves

First, the consequences of impedance mismatch:

wave machine demos:

matched impedance video

mismatched impedance video


page 7-15 in the book

length of antennas, velocity factor

The fundamental relationship is:

v = f . l

More or less v = c, (where c is the speed of light)

However v = vf . c, where vf is the velocoty factor: Some fraction or percentage of the speed of light.

For the purposes of this course, the number to remember for the speed of light is 300 million meters per second


The T-antenna gives rise to the schematic symbol for an antenna.

Antennas are tuned circuits: They include resistance and reactance; where there are equal amounts of capacitive and inductive reactance.

To see where the capacitance comes from, look at this animation showing the transformation from a capacitor to antenna.

more on dipoles

monpole and dipole radiation patterns

dipole and reflector animation

horn antenna animations


simplified yagi antenna animation

various yagi antenna field animations

yagi antenna block diagram (exam)

extra credit:
antenna basics, part 1
antenna basics part 2

This playlist of animations shows the electric field in the vicinity of various antennas.


read the chapter on propagation

read chapter 7, on transmission lines

read chapter 8, on antennas

video on Decibels

Extra credit:
video about microwaving grapes, in which grapes are the perfect size and shape to act as antennas in a microwave oven, and do interesting things as a result.

Class 5.5 (Self-Study) Propagation

radio waves in free space, propagation, antennas

video: RCAF training film on electromagnetic wave propagation


video: RCAF training video on directivity (very good)

video: RCAF training video on antenna bandwidth (very good)

Directive antennas work on the principle of interference, where waves add destructively or constructively. Here is an animation ofinterference.



Here is a very good army training video on ground wave and sky wave propagation. This basically teaches everything you need to know.

So called “sky-wave” propagation occurs because of the phenomenon of refraction, in which the speed of waves change depending on the medium. Here is an animation of refraction that shows waves changing direction as they cross a boundary between two media. In the ionosphere, the density of the ionosphere changes continuously, which causes a gentle curve rather than a sharp bend as shown here.

Extra credit: This video on so-called tropo scatter is mostly a waste of time.

Class 6: Receivers (ch 14), modulation (ch 13), block diagrams (ch 13)


In a previous class, we demonstrated a crude transmitter: A device that oscillated, and dumped energy into a propagating electromagnetic field in free space. We saw that in order to set up these oscillations, we used components that store energy in electric and magnetic fields.

In the next class, we learned about sending these waves over a cable, and then out through an antenna.

In this class, we will look at capturing waves, taking them apart, and turning them into intelligence.


Fundamental components and block diagram

This is a block diagram: It’s like a circuit, but….

Antenna (dealt with this already)

Tuned circuit, also called a selector
(dealt with this already)


This is the first of several block diagrams relevant to the exam.


diodes, converting AC to DC

First, the waves we’re receiving right now are amplitude modulated. That means the signal looks like this. (diagram) If we push that signal through a diode, then only some of it gets through. If we stuff that through an audio transducer, we hear the audio.

Video: cat’s whisker detector

Once again: There are conductors, semiconductors, dielectrics, insulators.

Semiconductors are interesting, in that by themselves they act like glass, but in the presence of an electric field, they act like conductors. The reasons for this are fascinating, technical, and too detailed to get into right now.

The frequency domain

First, review what we are familiar with: Graphs of amplitude vs time

We all remember what a sinusoidal waveform looks like.

We can also create other shapes of waveforms.

The Fourier transform, intuitively:

We demonstrate this with audio spectrograms: Whistling into microphones, running Baudline

takeaway: a time-domain waveform (may) consist of multiple frequency-domain signals

Next we talk about graphs of amplitude vs frequency. This site shows the frequency spectrum of different types of signals (including an impulse, as in the spark-gap transmitter).

video: RCAF training video that deals, in part, with the Fourier transform

video: building a square wave out a sine wave

video: building a triangle wave out of sine waves

animation: Fourier transform animation

a not very intuitive sound synthesis toy

The thing to remember is that any signal can be broken up into sine waves, and sine-waves self-propagate.

We choose not to do the following, for reasons of time (also the spectrum analyzer is broken)

spectrum analyzer and non-sinusoidal waves

spectrum of real-world square waves

(Advanced qualification) Signals can have a dc component as well as an AC component.

What if there is no audio signal? What if there’s just a carrier?


image of beat phenomenon, showing superposition or interference of waves

from this page

video of beats using tuning forks

video explanation

a simple tone generator


a more elaborate tone generator

Both produce the sound that sine waves and square waves make.

mixing an audio signal with a carrier

there is a similar phenomenon that occurs with radio signals, called mixing

Advanced: mixers

Advanced: “mixing” is due to non-linearity in the response of RF components, but it also happens in ears, too.

more detail

and more

beat frequency oscillator demo

modulation (introduction)

Depiction of OOK, in the frequency domain and time domain

Clarification: distinction between “continuous wave” and “damped wave” (rememebr when I said that ham radi ois very old? The abbreviation CW is a holdover from the spark-gap days, when it stood in distinction to “damped waves”)

Modulation (continued)

Depiction of AM, in the frequency domain

video: AM modulation demonstrated with an oscilloscope

AM modulation at the signal identification wiki)

Depiction of FM, in the frequency domain

FM signal on signal ID wiki

Sensitivity and selectivity

Sensitivity is a function of the detector. In the context of our crystal radios, some detectors are good. Other detectors are better.

The sensitivity of these point-contact diode detectors is pretty decent.

The sensitivity of these PN junction diodes is not as good.

Selectivity is a function of the tuned circuit (selector) and, in other types of receivers, the rest of the RF signal chain.

In class 5, we learned about the so-called Q-factor. The Q of these tuned circuits in our crystal receiver is low.

Other types of receivers

block diagram study page

Other types of modulation

PSK - phase shift keying

FSK - frequency shift keying

compare and contrast with



Self-study remainder of antenna chapter [Chapter n]

Watch various videos

Chapter 9 for next class

Video: secret life of machines: radio This half-hour video is worth watching beginning to end.

Here is a study guide for the various block diagrams found in the exam. In a basic qualification exam, there will be one question about each block diagram.

This is a very good and very clear army training video on FM modulation.

See also: (via VE7MHW)

Here is an animated video of how a crystal radio works.

(It also has a segment on how AM is modulated, then demodulated in the set)

Extra credit:

Class 7: Transmitters (ch 13), more block diagrams (ch 13)


the circuit

datasheet for crystal oscillator

iphone pinout

More on quartz oscillators [advanced]

waveform of quartz oscillator

quartz oscillator circuits


filtering, in the context of mixing and transmitters


active components:

tubes, semiconductors, transistors

bipolar transistors

field effect transistors

vacuum tubes

Triode tubes

tubes/valves vs transistors: it’s basically about power and heat. Vacuum tubes also require high voltages.


an amazing endless rant on how transistors work


amplifier characteristic curve, non-linearity

types of amplifiers (RF signal, audio, power)

frequency range - RF vs AF

voltage vs current vs power amplifers




power supplies

power supply block diagram



block diagram study page


Deferred to later


Can we hear the function generator on the radio? Yes we can. (Well, we can hear the silence.) Can we mix with the signal? Yes.

uses GDO, HT, signal generator

Class 8: Station Components (ch. 11), Interference & Suppression (ch 15)

Station components

HF station block diagram

digital station block diagram

HF station block diagram

digital stuff

digital system block diagram


harmonic distortion

(advanced) the following page shows that harmonic distortion comes from non-linearity in RF amps

Class 9 Regulations and Operation


The radiocommunications act is the applicable Canadian law.

The Radiocommunications Regulations define the amateur service.

The amateur service is described in an easyier-to-read document called RIC-3.

The operating rules are described in a document called RBR-4.

ISED produces several separate documents concerning Amateur Radio:

1) RBR-4, a regulatory document which establishes the operational and technical standards for stations in the Amateur Radio Service

2) RIC-1, a policy document which sets standards for the conduct of examinations for Amateur Radio Certificates and standards for Accredited Examiners (AEs)

3) RIC-3, which provides general information about the Amateur Radio Service and the privileges of each qualification

4) RIC-9, a policy document which details the call sign policy for Amateur Radio

There is a chart that illustrates the spectrum allocations in Canada.

The chart is based on the 2018 table of allocations, which is quite long. In fact it is so long it is divided into many different sections.

Here is a chart that shows the whole world.. Note the different between ITU regions.

Regulatory stuff can and should be self-studied throughout the course.

Currently, under the Radiocommunication Act, while listening is not prohibited, it is an offence to divulge or use information obtained from non-broadcast radio signals without the permission of the people who sent the messages.



Operating procedures

CW Operation Video

Getting started on HF

video on various digital modes

Safety (self-study)

Things to memorize

Everything Else

Practical Exercises

Crystal Receiver

point contact diode

coil calculator

more useful information

Rimstar’s crystal radios page

images of older crystal radios

images of polyfilm variable capacitor in crystal radios

coupling to headphones

many more crystal radio sets than may be healthy

irony of AM radio (content warning)

building fahnestock clips

Audio Amplifier

Basic Certificate

For the basic certificate, it is sufficient to study a simple single-transistor power amplifier.

We use the term power amplifier here as distinct from, say, a signal amplifer, or a voltage amplifier, or a current amplifier. To achieve power amplification, power amplifier must amplify both the voltage and power.

The following links serve as background for the in-class exercise (to be described elsewhere):

single-transistor amplifier for crystal sets, from “Rimstar”

Funway single transistor amp

various circuits

yet another purported example

and another

and another

single-transistor amplifiers, in detail

Advanced Certificate

Two-stage power amplifier

buffer amplifiers

classes of amplifiers

Single-Transistor amplifier from Sparkfun

common emitter schematic

detailed explanation of common-emitter amplifiers

emitter resistance

Troubleshooting this circuit

This amplifier’s output will be connected to a high impedance, so we consider this current to be zero. Notably, a speaker is not a high impedance (8Ω is typical). If you want to connect this circuit to a speaker, you need a buffer amplifier.

Another person with the same problem: Why can’t class A amp drive 8 ohm speaker with just one BJT?

Any discussion of transistor amplifers inevitably ends up being a discussion on Biasing Transistors, discussed in the links that follow.

The propoer way to do it is described at this page about
biasing transistors in excruciating detail

But after some some hand-wringing about basic electronics, from hackaday some folks had the bright idea to write about it in a bit more accessble way…

So here we have a discussion about common-emitter amplifers, from hackaday that includes some helpful rules of thumb:

For example:

  • Pick a collector resistor using Ohm’s Law to deliver the desired maximum current when the transistor is saturated,
  • then make a few guesses with the bias resistors by making their total value over 10 times the collector resistor and
  • the ratio of upper bias resistor to lower one being about 2 to 1.

See also this discussion about biasing common-base transistor amplifers.

lovingly hand-crafted page on transistor circuits

capacitor markings for various values

Transistor Radio

Here is an article from hackaday about a book on making a transistor radio. Here is the whole book in a web viwer, and here is the PDF.

“three-penny radio”


three-componenent AM transmitter

Reference Information

electrostatic smoke precipitator

General Technical Content

electronics, etc, following the map I have drawn out on paper. Major sections so far are

The electromagnetic specrum

DC power

AC power

The Time Domain

The Frequency Domain, audio frequencies

Modulation and things, more complicated radios


In-Class Demonstrations

Passive Demonstrations

Satellite Views

via, also


This web SDR is pointed at a geostationary communications satellite.


We need:

flux pen

CW (Bob? Terrace club?)

CW is no longer a requirement but in the event that one wants to learn it after qualifying the following is a good program. Go the following site and download Version 9, a “freebie”. One caveat - it only works on the WINDOWS platform.

FYI, another way to acquire the equivalent of Basic with Honours is to to qualify with CW at 5 wpm. Details at:

CW Skimmer software works on Windows to reliably decode CW.

code practice schedule

Scheduling & Administrivia

This section deals with course administration.

Scheduling & Fees

Introductory sessions are provided free. The long-form course fee is $60, with all materials provided including textbook. Also includes exam and BVARS membership.

The short course fee is $30, including the textbook.


Various possibilities:

Classes held on rotating days of the week

Long-form classes are held weekly on Monday evening at Ranger Park building in Smithers. Expected duration eight weeks. Schedule determined in consultation with students.

Two introductory sessions: February 26 7-9 PM, and Saturday March 2 12-2 PM.


There are two priominent licensing textbooks in Canada:

Textbooks available to loan, or purchase for $30.

Course Promotion

create a group


List of bulletin boards

Community Radio Station

ISS Video

20 m DX



music: radar rider

conversation stack (interesting, but not for now)

Mailing LIsts


Education and training are eligible for funding by Community Gaming Grants.

Misc Resources

(to be organized later)

How to Solder

Excellent Pace training videos. This is how I learned.

1. Solder and Flux

There are two types of ham radio operator.

similarities of wave behaviour

It’s not cheap, but I’m sure the government will buy it.

There is a list of web SDRs that you can use to listen to the HF bands online. There is one in the netherlands that is rather good. Here is a map. Here is a different kind of map. Here is another credible list.

for example

vacuum tube reciever

video: use a scope to match an antenna and measure impedance

Transistor Diode Model

kjs crystal radio, big litz

A Good Crystal Radio Design With Some Justification

A Good Crystal Radio Design With Some Justification

pretty good notes on a bunch of topics

To be deployed when I need to hand-wave something away: You can tell something is a tautology because of the way it is

If somebody buys me one of these I will be happy. My copy is missing a few key pages.

playlist of electronics training videos

darth vector’s youtube channel

imaginary numbers

Let’s talk about radios.

The following is the beginning of a history lesson that will continue throughout the course.

Once upon a time the technology of radio was brand new, and exciting for all the same reasons that technology like virtual reality or genetic engineering are exciting.

Here is a chart of technology adoption, which helps to explain why radios are what they are today. Here is a different kind of chart, which speaks to some of the same things.

(I got the chart from an interesting article on the microwave oven.)

Radios are powerful.

For example, the Nazis loved radio.

For the community radio station CICK in the train car, the orientation manual effectively says, “you may not use the radio to overthrow of government.” (Specifically, the wording prohibits “Any remark which advocates or teaches the use of force to change the Government of Canada.”)

As this course progresses, you will see how simple it is to construct a radio. Because it is so relatively straightforward, in the early twentieth century (prior to the first world war) there were a large number of people operating home-built radios who were literally amateurs — enthusiastic non-professionals having fun.

What follows is a not-so-brief digression into amateur radio history:

The nature of early radio transmitters was such that every station could hear every other station nearby, simultaneously, all the time. The result was a form of chaos, or anarchy.

(For a technical explanation, this wikipedia article is a start.)

However, transmissions did not propagate more than a few hundred kilometers, meaning that people had to figure out how to relay messages in an organized fashion.

US govt passed the Radio act of 1912 in response to the confusion that was involved in the sinking of the Titanic. There was also the international ratdiotelegraph conference of 1912.

Effectively, what happened was that the Titanic was transmitting superfluously when it should have been monitoring local traffic. It might have heard the warnings of icebergs from surrounding ships.

Full text of the act

There is a very long presentation that contains more than you would ever want to know about radios on the titanic

Amateurs were restricted to wavelengths less than 200 m, which at the time were thought to be useless.


The American Radio Relay League was founded in 1914, but war broke out a few months later and fully three quarters of American radio operators were sent to war. Non-military radio transmissions banned 1914-1919 in USA.

In Britain, the fear was that amateur radios could be used for spying.

Amateur operators advocated that politicians direct the US navy to relinquish control…

So there was a great deal of technical development during the first world war. We get things like vacuum tubes, better receivers, better transmitters. Armed with this surplus military technology, amateur operators figured out that you could, using these formerly “useless” shorter wavelengths, communicate across the Atlantic. (We will learn why this is in a later class, on radio propagation.)

With vacuum tubes, you also get oscillators, and the possibility of voice practical voice transmission. So after 1918, the adoption of radios among the general population starts to begin. (See the technology adoption chart.)

Then the roaring twenties happen…

And then the depressing thirties… Nobody’s got any money, so the people who are experimenting with radio are, well, well-off.

Just take a look at the pictures and prices this old handbook.

FM invented and used by amateur radio experimenters at this time.

In USA, foreign communication banned 1940. All operation banned again during the second world war.

More on the ban.

FM used extensively in the war.

Single sideband invented in the fifties, allowing more efficient use of spectrum and power.

Canadian Amateur Radio Federation founded in 1967. Precursior to RAC.


And so on.

There are some radios that you use to listen, and some radios that you use to talk.

The radios that you use to listen are, effectievly, unregulated.

The radios that you use to talk are tightly regulated.

The radios that anybody can talk on, are, frankly, kind of lame.

I’m talking about walkie talkies, FRS radios, CB radio. Also cell phones, WiFi.

They are made to do only one thing, and you can’t adjust them.

(At least you’re allowed to use encryption over WiFi…)

The radios that are more exclusive are more versatile.

bush radios, marine radios, radars, amateur radars…

How versatile? Well.

The big idea here is that governments have been sufficiently afraid of amateur radio operators that, at various times and places places in the world, there have been crackdowns to civilize the hobby, several outright bans, and restrictions to make sure that the government knew exactly where operatators were, and what they were doing. Directories of operators were published. (This partially still happens today.) Detailed logs had to be kept.

The way this continues today is that you’re not allowed to obscure who you are, and what you’re saying.

A list of contests ongoing at any time

modular transceiver

qrp labs

Crystal radio design

kjs crystal radio, big litz

A Good Crystal Radio Design With Some Justification

A Good Crystal Radio Design With Some Justification

simplest fm receiver

electroluminescent receiver

For example, there are quite a few ham data networks:

Here is a map of one of them.

feedlines [advanced]

energy transfer in DC circuits

telegraphers equations

via this question

different explanation of the same

about baluns

high-voltage DC power lines, why?

Ham radio is a very old hobby.

Like many things that are very old, it is highly problematic when it comes to things like diversity, accessibility, and inclusivity. Therefore, there is lots of work to do to make it work better for everyone.

As an example, I quite like this summary of a conference presentation called A Future History of the Solarpunk Ham Radio Club, which is worth including in its entirety here:

In 2016 a disaster response network of trained radio users sporting an ideal budget of $0 per person was born. While amateur radio existed through most of the 20th Century, by the 21st century it had become a bourgeois hobby for older white men. The established purpose of amateur radio in the regulations of the FCC had always been to set up a voluntary interest in radios for use in emergency (both environmental and military), but with the rise of commercial Internet radio networks (Wi-Fi) and cheap long-haul telecommunications networks, ham radio shacks became a collection of exclusive and fetishized gadgets. Younger people drifted towards the Internet.

But in 2016, emergency came calling. A group of three coastal superstorms flooded most of the West Coast, and left the population without infrastructure for weeks. A small, previously unknown group calling themselves “Solarpunks” sprang up, to fill the communication gap. Using a number of levels of financial commitment—$0, $10, and $40—they began training a culture of youth hungry for the basic skills of radio and electronics, and then letting them train others. They descended upon the rubble to pull out bits of aluminum for antennas, drying out coaxial cable, and rescuing batteries and stereo speakers from stranded vehicles. Using the disabled tech of a failed infrastructure, they began connecting themselves into a network of learning and doing. The old-guard hams had all fled to high grounds weeks ago, but the Solarpunks remained, continued their modifications and grew in numbers.

We will detail the speculative future-history of the Solarpunk Ham Radio Club and its method of spreading the use of radio with no financial investment. It took amateur radio back from a toxic commodity culture, just when it was needed most. The Solarpunks couldn’t duplicate the permanent infrastructure that needs billions of dollars in funding. But with a foothold based on a resilient jugaad rather than expensive gadgets, they were able to find a way of teaching each other, that made their network resilient in a way that money could not.

The website Hack-A-Day has a couple of opinion pieces on the state of ham radio at the moment:

Here is another page from an academic at Concordia university, which includes an interesting question:

Q: The first question is usually “Why use amateur radio when you can use the phone and/or Internet”?

A: This question is almost impossible to answer. Why do some people ride a motorcycle if they can drive a car? Why read books if there is TV? And so on…