• Quick Links
    Listen live to Smithers amateur scanner

    A convenient web-SDR (see more far below)

    Local community broadcast station CICK 93.9 MHz (listen live)

  • Course Content, Notes, Homework, etc.

    This section includes the material covered in each class. The most recent was class 7. The next is class 8.

  • Exam Outline, Question Bank, Study Aids

    The structure of the exam is somewhat different from the structure of the course. I would argue that the exam has some serious shortcomings as a teaching tool, and is therefore not a great foundation for learning.

    However, knowing the content of the exam is essential for obtaining the license, and so it is presented comprehensively here.

  • Scheduling & Administrivia

  • Misc Resources

    (to be organized later)

  • Class 1: Registration, Introduction, Familiarization

  • Class 2: Basic Electricity

  • Class 3: Basic Electricity, part 2.

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

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

  • Class 5.5 (Self-Study) Propagation

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

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

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

  • Class n+1: (weekend?) Regulations and Operation

    Safety (self-study)

  • Things to memorize

  • Everything Else

  • Scheduling & Fees

  • Introductory sessions are provided free. Course fee is $60, with all materials provided including textbook. Also includes exam and BVARS membership.

  • 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.

  • Textbooks

    There are two priominent licensing textbooks in Canada:

  • Course Promotion

  • Funding

  • 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.

  • Why might you be interested in radios?

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

  • Q&A

    Get to know the class. Interests, education, background.

  • Administrivia: Sign-up, distribute books

  • Demonstrations: What you can do on the radio

  • Homework!

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

  • In the first class, we introduced about the electromagnetic spectrum…

  • What are radio waves made from?

  • Basic Electricity

  • Administrivia

  • Homework

    Read the book, watch some videos

  • Basic Electricity

  • Conclusion of basic electricity part 1: DC power

  • Basic electricity, part 2: alternating current

  • Homework

    Watch some videos, read the book.

  • Review up to now

    • we talked about electricity and batteries. We dealt with the concepts of voltage, current, and resistance.
    • we talked about electricity and wall outlets, and talked about power. We looked at AC waveforms. We talked about AC power and resistors.

    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.

  • Beginning electromagnetism: current in a wire, and consequences thereof

  • Electromagnetic waves

  • inductors, an introduction

  • capacitors, an introduction

  • impedance, an introduction

  • Hands-On

  • Summary:

    • There are these things called fields.
    • The fields represent the presence or absence of potential energy.
    • When the fields change, energy moves.
    • Both fields exist at once.
    • Also, when the fields change, they disturb each other.
    • There are two components that host changing fields.
    • The presence of these changing fields prevents or allows energy to flow in a circuit.
    • There can be many ripples on the surface of a pond. Likewise, there can be many frequencies present in a signal. If you are a boat, some waves bother you and some waves dont.
    • The quantity that determines whether certain waves, or frequencies, bother the non-dissipative passive components is called reactance.
    • […]

  • Homework

  • advanced material

  • impedance

  • resonance

  • q-factor

  • filters

  • feedlines

  • standing waves

  • length of antennas, velocity factor

  • antennas

  • Homework

  • radio waves in free space, propagation, antennas

  • antennas

  • propagation

  • Introduction

  • Receivers

    Fundamental components and block diagram

  • Hands-On

  • diodes, converting AC to DC

  • The frequency domain

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

  • modulation (introduction)

  • Modulation (continued)

  • Sensitivity and selectivity

  • Other types of receivers

  • Other types of modulation

  • Administrivia:

  • Homework

    Self-study remainder of antenna chapter [Chapter n]

    Watch various videos

    Chapter 9 for next class

  • Transmitters

    • oscillators
    • filters, in the context of transmitters

  • diodes

    • terminal names
    • zener diodes
    • rectifiers
    • LEDs
    • biasing

  • active components:

    tubes, semiconductors, transistors

  • amplifiers

  • power supplies

    power supply block diagram

    • transformer
    • rectifier
    • filter
    • regulator

  • Homework:

  • Deferred to later

  • Regulations

  • Operations

  • Practical Exercises

  • General Technical Content

  • In-Class Demonstrations

    • Variac, other variac, oscilloscope, multimeter
    • Antenna analyzer

  • Passive Demonstrations

    • WSJT and Grid Tracker
    • Satellite contact, ISS APRS beacon
    • SDR

  • Soldering

  • CW (Bob? Terrace club?)

  • Basic Electronics and Theory - 005 (13 questions)

  • Feedlines and Antenna Systems - 006 (13 questions)

  • Radio Wave Propagation - 007 (8 questions)

  • (Active) Circuit Components - 004 (6 questions)

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

  • Interference and Suppression - 008 (5 questions)

  • Regulations and Policies - 001 (25 Questions)

  • Operating and Procedures - 002 (9 questions)

  • Textbooks available to loan, or purchase for $20.

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

  • 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.

  • Radios are powerful.

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

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

  • 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.

  • 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.

  • 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.

  • 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!

  • 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.

  • Lots of reasons!

    Things that are useful, things that are fun, and things that are in-between.

  • useful communications

    • emergency response
    • emergency preparedness
    • situational awareness

  • in-between

    • experimentation
    • building: receivers, transmitters, instruments, antennas, repeater networks, solar power, computer systems and networks…

  • fun communications

    • exploration - DXing, etc
    • rag-chewing
    • contesting
    • competitive direction-finding (AKA fox hunting)
    • Questions from the class?
    • How many of you are nerds? Eggheads?Tinkerers? How many of you are preppers? How many of you are gearheads, weekend warriors, mall ninjas? To what extent do you identify with the word “tacticool”??
    • Intent to pass the exam?
    • Interest in morse code?
    • Interest in soldering?

  • In the Bulkley Valley:

    • talk or listen to the repeater network
    • HF comms around the world using various modes and systems
    • help out with BV search and rescue
    • help build and maintain the repeater network. (We just linked to Terrace, next stop is Prince Rupert!)
    • comms for triathlons, trade show — good practice for emergencies!

  • Building:

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

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

  • Some acceptable answers: electricity, magnetism

  • what is electricity made from?

  • what is magnetism made from?

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

  • we have to talk about electricity first

  • two obvious places to start: wall outlets, and batteries

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

  • electricity-water analogy

  • voltage

  • current

  • single resistors: Ohm’s law

  • resistors in parallel

  • resistors in series

  • voltage dividers

  • Book:

  • Videos

  • theory and definition of electric power

    power = current * voltage

  • 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?)

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

  • household outlets - AC

  • AC power

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

  • As quickly as possible….

  • electric fields

  • DC current in a wire

  • illustrations of the following topics

  • electric field around a wire

  • magnetic field around a wire

  • changing current in a wire

  • spark-gap transmitter

  • nature of electromagnetic waves

  • properties of waves

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

  • inductors and fields

  • transformers

  • inductive reactance

  • capacitors and fields

  • capacitive reactance

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

  • Signals flow in inverse proportion to the impedance presented.

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

  • 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.

  • The difference between resistance and reactance is that resistance is dissipative — it converts energy into heat, but reactance does not; it simply sloshes it energy around for a while before giving it back.

  • Impedance includes the effects of resistance and reactance. As we saw, reactance varies with frequency.

    Consequently, impedance varies with frequency.

  • A circuit may presents low impedance at certain frequencies and accepts them, but reject them at other frequencies. The difference between a circuit accepting or rejecting frequencies results in current flowin a lot, a little, or not at all.

  • The thing that makes radio interesting is that a signal consists of many frequencies at once.

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

  • 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 filtering effect — just not as much as at the resonance point. So, the phenomena of resonance has some “width” associated with it.

  • 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.)

  • 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.

  • 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

  • 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.

  • 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.

  • 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.

  • 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)

  • Detector

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

  • 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.

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

  • The Fourier transform, intuitively:

    • Signals consist of many frequencies, all at once.
    • Even when a signal consists of mostly one frequency, the others are merely small, not zero.

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

  • 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).

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

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

  • Depiction of OOK, in the frequency domain and time domain

  • Depiction of AM, in the frequency domain

  • Depiction of FM, in the frequency domain

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

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

  • PSK - phase shift keying

    FSK - frequency shift keying

    compare and contrast with
    OOK

  • Weekend session: May 11

  • bipolar transistors

    field effect transistors

    vacuum tubes

    • two types of each: NPN & PNP, or N-channel and P-channel
    • terminal names (table 9-1, page 9-14)
    • FETs are voltage-controlled, BJTs are current-controlled (roughtly)

  • Triode tubes

    • Layout

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

  • (Advanced)

  • amplifier characteristic curve, non-linearity

  • types of amplifiers (RF signal, audio, power)

  • frequency range - RF vs AF

  • voltage vs current vs power amplifers

  • gain

  • linearity

  • distortion

  • mixing

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

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

  • Crystal Receiver

  • Audio Amplifier

  • Transistor Radio

  • Transmitter

  • Reference Information

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

    • electromagnetism, fields, electromagnetic circuits, electromagnetic waves
    • conductors, insulators, dielectrics, semiconductors
    • voltage and resistance and power

  • The Frequency Domain, audio frequencies

    • capacitors, inductors, impedance, transmission lines

  • Modulation and things, more complicated radios

  • We need:

    • A few irons
    • Lots of flux
    • Lots of wire
    • clippers, strippers
    • Solder
    • Something to build

  • 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.

    http://www.g4fon.net/

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

    https://wp.rac.ca/requirements/

  • CW Skimmer software works on Windows to reliably decode CW.

  • code practice schedule

  • Basic electricity (all covered in class 2&3)

  • Electromagnetism (class 4)

  • misc

  • feedlines (class 5)

  • antennas (class 5, beginning)

  • types of propagation &
    the ionosphere

  • practical considerations

    • 4-1 amplifier fundamentals
    • 4-5 triode vacuum tube fundamentals
    • 4-3 bipolar transistor fundamentals

    • 4-4 field-effect transistor fundamentals

    • 4-2 diode fundamentals

    • 8-1 front-end overload, cross-modulation
    • 8-2 audio rectification, bypass capacitors, ferrites
    • 8-3 intermodulation, spurious, key-clicks
    • 8-4 harmonics, splatter, transmitter adjustments
    • 8-5 use of filters: low-pass, high-pass, band-pass, band-reject

  • licenses

  • nature of amateur communications

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

    • bands
    • bandwidth
    • power
    • clean signals

  • legal operation

  • playing nice with others

  • international stuff

  • interference

    • 2-1 voice operating procedures - channelized VHF/UHF repeater
    • 2-2 phonetic alphabet
    • 2-3 voice operating procedures - simplex VHF/UHF and HF
    • 2-4 tuneups and testing, use of dummy load, courteous operation
    • 2-5 Morse (CW) operating procedures, procedural signs
    • 2-6 RST system of signal reporting, use of S meter
    • 2-7 Q signals
    • 2-8 emergency operating procedures
    • 2-9 record keeping, confirmation practices, maps/charts, antenna orientation

  • create a group

  • List of bulletin boards

    • Petro Can (south exterior wall)
    • Two Sisters (inside, bathrooms)
    • Town hall (inside)
    • No Frills (inside)
    • Central Park building (outside)
    • Mtn Eagle Books (outside)
    • Public Library (inside)

  • 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.

  • 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.

  • 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.

  • 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.

  • 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.

  • 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.

  • 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.

  • 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.

  • The radios that are more exclusive are more versatile.

  • How versatile? Well.

  • What are the shortcomings?

    What might be the world to come?

  • Try as many chapter quizzes as you wish

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

    • review relevant parts of the chapter
    • bring questions to next class

  • both are correct

  • acceptable answers: electrons, electric fields

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

  • analogy between voltage and static pressure

  • analogy between speed and current

  • analogy between resistance and friction

  • analogy between power and flow rate

      • 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

      • This site talks about electrical-mechanical analogies in quite a lot of detail, far too much detail to be of use really

      • power: peak voltage, RMS voltage, peak current, RMS current

      • a bit of calculus for the high-school students

      • why 60 Hz? wikipedia

        Of interest is the 400 Hz hum of aircraft. mains hum

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

      • 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

      • 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?

      • electric field between two plates

      • accelerating electrons, consequences thereof

      • switched dc current, consequences thereof

      • 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”

      • https://www.wyzant.com/resources/lessons/science/physics/magnetism

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

      • 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.

      • the magnetic field in an inductor is due to the current in the coils.

      • 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 DC, it looks just like

      • 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.

      • 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 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

      • detailed page about inductive reactance

      • inductive reactance video

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

      • same as inductors offer an opposition to ac currents, capacitors offer an opposition to dc 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

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

      • general definitions of imepdance

        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.

      • https://en.wikipedia.org/wiki/Wave_impedance
        https://en.wikipedia.org/wiki/Impedance_of_free_space

      • 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.

      • We all remember what a sinusoidal waveform looks like.

      • We can also create other shapes of waveforms.

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

      • spectrum analyzer and non-sinusoidal waves

      • 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”)

      • FM signal on signal ID wiki

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

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

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

        • 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.

        • The electromagnetic specrum

        • DC power

        • AC power

        • The Time Domain

          • Amplifiers

            • 5-2 concepts of current, voltage, conductor, insulator, resistance
            • 5-3 concepts of energy and power, open and short circuits
            • 5-4 Ohm’s law - single resistors
            • 5-5 series and parallel resistors
            • 4-6 resistor colour codes, tolerances, temperature coefficient
            • 5-6 power law, resistor power dissipation
            • 5-7 AC, sinewave, frequency, frequency units
            • 5-9 introduction to inductance, capacitance
            • 5-10 introduction to reactance, impedance
            • 5-11 introduction to magnetics, transformers (Class 5)
            • 5-12 introduction to resonance, tuned circuits (class 5)
            • 5-1 metric prefixes — pico, micro, milli, centi, kilo, mega, giga
            • 5-13 introduction to meters and measurements
            • 5-8 ratios, logarithms, decibels
            • 6-1 feed line characteristics, characteristic impedance
            • 6-2 balanced and unbalanced feed lines, baluns
            • 6-3 popular antenna feed line and coaxial connector types
            • 6-4 line losses by line type, length and frequency
            • 6-5 standing waves, standing wave ratio, SWR) meter
            • 6-6 concept of impedance matching
            • 6-7 isotropic source, polarization via element orientation
            • 6-8 wavelength vs physical length
            • 6-9 gain, directivity, radiation pattern, antenna bandwidth
            • 6-10 vertical antennas - types, dimensions, characteristics
            • 6-11 Yagi antennas - types, dimensions, characteristics
            • 6-12 wire antennas - types, dimensions, characteristics
            • 6-13 quad/loop antennas - types, dimensions, characteristics
            • 3-9 functional layout of Yagi-Uda antennas

          • Types of Waves

            • 7-1 line of sight, ground wave, ionospheric wave (sky wave)

            The Sun and the Ionosphere

            • 7-5 solar activity, sunspots, sunspot cycle
            • 7-2 ionosphere, ionospheric regions (layers)

            Propagation

            • 7-3 propagation hops, skip zone, skip distance
            • 7-4 ionospheric absorption, causes and variation, fading, phase shift, Faraday rotation
            • 7-6 MF and HF, critical and maximum useable frequencies, solar flux
            • 7-7 VHF and UHF, sporadic E, aurora, ducting
            • 7-8 scatter - HF, VHF, UHF
            • 3-10 receiver fundamentals
            • 3-11 transmitter, carrier, keying, and amplitude modulation fundamentals
            • 3-12 carrier suppression, SSB fundamentals
            • 3-13 frequency and phase modulation fundamentals
            • 3-5 functional layout of SSB)/CW receivers
            • 3-4 functional layout of CW transmitters
            • 3-6 functional layout of SSB transmitters
            • 3-2 functional layout of FM transmitters
            • 3-3 functional layout of FM receivers
            • 3-1 functional layout of HF stations

            pg 11-11

            • 3-7 functional layout of digital systems
            • 3-14 station accessories for telegraphy, radiotelephony, digital modes
            • 3-15 digital mode fundamentals RTTY, ASCII, AMTOR, packet
            • 3-8 functional layout of regulated power supplies
            • 3-16 cells and batteries, types, ratings, charging
            • 3-17 power supply fundamentals
            • 3-18 electrical hazards, electrical safety, security
            • 3-19 electrical safety ground, capacitor discharge, fuse replacement
            • 3-20 antenna and tower safety, lightning protection
            • 3-21 exposure of human body to RF, safety precautions
            • 1-1 radio licences, applicability, eligibility of licence holder
            • 1-2 licence fee, term, posting requirements, change of address
            • 1-3 licence suspension or revocation, powers of radio inspectors, offences and punishments
            • 1-4 operator certificates, applicability, eligibility, equivalents, reciprocal recognition
            • 1-22 examinations - Department’s fees, delegated examinations, fees, disabled accommodation
            • 1-7 content restrictions - non-superfluous, profanity, secret code, music, non-commercial
            • 1-13 station identification, call signs, prefixes
            • 1-12 non-remuneration, privacy of communications
            • 1-15 frequency bands and qualification requirements
            • 1-16 maximum bandwidth by frequency bands
            • 1-17 restrictions on capacity and power output by qualifications
            • 1-18 unmodulated carriers, retransmission
            • 1-19 amplitude modulation, frequency stability, measurements
            • 1-6 operation of radio apparatus, terms of licence, applicable standards, exempt apparatus
            • 1-5 operation, repair and maintenance of radio apparatus on behalf of other persons
            • 1-8 installation and operating restrictions - number of stations, repeaters, home-built, club stations
            • 1-9 participation in communications by visitors, use of station by others
            • 1-11 emergency communications (real or simulated), communication with non-amateur stations
            • 1-23 antenna structure approval, neighbour and land-use authority consultation
            • 1-24 radio frequency electromagnetic field limits
            • 1-14 foreign amateur operation in Canada, banned countries, third-party messages
            • 1-20 International Telecommunication Union (ITU) Radio Regulations, applicability
            • 1-21 operation outside Canada, ITU regions, reciprocal privileges, international licences
            • 1-10 interference, determination, protection from interference
            • 1-25 criteria for resolution of radio frequency interference complaints

          • 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

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

          • 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…)

          • bush radios, marine radios, radars, amateur radars…

          • 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—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.

          • 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…

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

          • 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. These days it can even be a full-fat digital medium.

          • the current exhibits beats because each side is connected to a resonant circuit. So 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.

          • uses GDO, HT, signal generator

            • 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.
            {"cards":[{"_id":"655a38984450703f0b0004a6","treeId":"655a38b74450703f0b0004a4","seq":18927099,"position":1,"parentId":null,"content":"# Principles of Amateur Radio\n\nThis is a comprehensive outline of the basic certificate licensing course presented by the [Bulkley Valley Amateur Radio Society](http://www.bvars.org/) in the Spring of 2019.\n\nQuestions may be directed by email to: ve7rbh@rac.ca\n\n** Read cards left to right, or top to bottom. Use keyboard, mouse, or touch to navigate.**\n\n*This document is a work in progress.* It is available on the web at:\nhttps://gingkoapp.com/principles-of-ham-radio\n\nThe [printable version of this page](https://gingkoapp.com/principles-of-ham-radio.html) may be useful if the interactive presentation is incompatible with your web browser.","deleted":false},{"_id":"637590f95d0fbe476c0001d3","treeId":"655a38b74450703f0b0004a4","seq":18929551,"position":0.125,"parentId":"655a38984450703f0b0004a6","content":"**Quick Links**\nListen live to [Smithers amateur scanner](http://209.145.117.13:1088/broadwave.mp3)\n\nA convenient [web-SDR](http://websdr.ewi.utwente.nl:8901/m.html) (see more far below)\n\nLocal community broadcast station [CICK 93.9 MHz (listen live)](http://usa13.fastcast4u.com/proxy/smithers?mp=/1)"},{"_id":"654fb37b305a6842700000cf","treeId":"655a38b74450703f0b0004a4","seq":17553374,"position":0.25,"parentId":"655a38984450703f0b0004a6","content":"## Course Content, Notes, Homework, etc.\nThis section includes the material covered in each class. The most recent was class 7. The next is class 8."},{"_id":"63766e605d0fbe476c0001c0","treeId":"655a38b74450703f0b0004a4","seq":16821862,"position":0.625,"parentId":"654fb37b305a6842700000cf","content":"## Class 1: Registration, Introduction, Familiarization"},{"_id":"655a22c64450703f0b0004ad","treeId":"655a38b74450703f0b0004a4","seq":16830533,"position":0.140625,"parentId":"63766e605d0fbe476c0001c0","content":"### **Background and Motivation**\n\nAmateur 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."},{"_id":"63684fb953b88b9b4600039d","treeId":"655a38b74450703f0b0004a4","seq":16830551,"position":0.25,"parentId":"655a22c64450703f0b0004ad","content":"There are lots of ways to teach. There are lots of ways to learn.\n\nThe 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."},{"_id":"636826aa53b88b9b460003a2","treeId":"655a38b74450703f0b0004a4","seq":16830549,"position":1,"parentId":"63684fb953b88b9b4600039d","content":"What are the shortcomings?\n\nWhat might be the world to come?"},{"_id":"655a1e874450703f0b0004af","treeId":"655a38b74450703f0b0004a4","seq":16830285,"position":0.5,"parentId":"655a22c64450703f0b0004ad","content":"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."},{"_id":"655a30a84450703f0b0004aa","treeId":"655a38b74450703f0b0004a4","seq":17336152,"position":1,"parentId":"655a1e874450703f0b0004af","content":"As an example, I quite like this summary of a conference presentation called [A Future History of the Solarpunk Ham Radio Club](https://radicalnetworks.org/archives/2015/speakers/adam-rothstein/), which is worth including in its entirety here:"},{"_id":"6374fedf5d0fbe476c0001e0","treeId":"655a38b74450703f0b0004a4","seq":16821234,"position":0.25,"parentId":"655a30a84450703f0b0004aa","content":"> 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.**"},{"_id":"6374ff0f5d0fbe476c0001df","treeId":"655a38b74450703f0b0004a4","seq":16821233,"position":0.5,"parentId":"655a30a84450703f0b0004aa","content":"> 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."},{"_id":"655a2f574450703f0b0004ab","treeId":"655a38b74450703f0b0004a4","seq":16821230,"position":1,"parentId":"655a30a84450703f0b0004aa","content":"> 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**."},{"_id":"655a37064450703f0b0004a7","treeId":"655a38b74450703f0b0004a4","seq":16830278,"position":2,"parentId":"655a1e874450703f0b0004af","content":"The website Hack-A-Day has a couple of opinion pieces on the state of ham radio at the moment:"},{"_id":"6376289d5d0fbe476c0001c9","treeId":"655a38b74450703f0b0004a4","seq":16821238,"position":1,"parentId":"655a37064450703f0b0004a7","content":"* [Ham Radio Just Isn't Exciting](https://hackaday.com/2017/08/01/amateur-radio-just-isnt-exciting/)\n* [Ham Radio: Hacker's Paradise](https://hackaday.com/2013/09/23/guest-rant-ham-radio-hackers-paradise/)\n* and also [A return to hacker's paradise](https://hackaday.com/2013/11/13/bitx-a-return-to-hackers-paradise/)"},{"_id":"655a24f04450703f0b0004ac","treeId":"655a38b74450703f0b0004a4","seq":16830279,"position":3,"parentId":"655a1e874450703f0b0004af","content":"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](https://uwaterloo.ca/environment-resources-and-sustainability/sites/ca.environment-resources-and-sustainability/files/uploads/files/ers_475_raadio.pdf)"},{"_id":"653c12bce8acad334d000125","treeId":"655a38b74450703f0b0004a4","seq":16830280,"position":4,"parentId":"655a1e874450703f0b0004af","content":"Here is another [page from an academic at Concordia university](https://users.encs.concordia.ca/~paknys/amateurradio.html), which includes an interesting question:"},{"_id":"653c1228e8acad334d000126","treeId":"655a38b74450703f0b0004a4","seq":16821249,"position":1,"parentId":"653c12bce8acad334d000125","content":"Q: The first question is usually **\"Why use amateur radio when you can use the phone and/or Internet\"?**\n\nA: 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...\n\n"},{"_id":"6368581653b88b9b4600039c","treeId":"655a38b74450703f0b0004a4","seq":16830298,"position":5.25,"parentId":"655a22c64450703f0b0004ad","content":"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."},{"_id":"6477ed7f689a48b09f0006d0","treeId":"655a38b74450703f0b0004a4","seq":17336171,"position":9,"parentId":"655a22c64450703f0b0004ad","content":"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!"},{"_id":"626320e9001682e70f000349","treeId":"655a38b74450703f0b0004a4","seq":17336233,"position":10,"parentId":"655a22c64450703f0b0004ad","content":"Why am I harping on the fundametals so much? Because technology is not about applications.\n\nI'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.\n\nThe 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*.\n\nIf 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."},{"_id":"63766c315d0fbe476c0001c2","treeId":"655a38b74450703f0b0004a4","seq":16834579,"position":0.25,"parentId":"63766e605d0fbe476c0001c0","content":"### **Why might you be interested in radios?**\n\nAs I see it, for things that are useful, for things that are fun, and for things that are in-between."},{"_id":"637489b4a4889556960001e8","treeId":"655a38b74450703f0b0004a4","seq":17336256,"position":0.5,"parentId":"63766c315d0fbe476c0001c2","content":"**Lots of reasons!**\n\nThings that are useful, things that are fun, and things that are in-between."},{"_id":"63766a595d0fbe476c0001c3","treeId":"655a38b74450703f0b0004a4","seq":16821879,"position":1,"parentId":"63766c315d0fbe476c0001c2","content":"useful communications\n* emergency response\n* emergency preparedness\n* situational awareness"},{"_id":"653c9957e8acad334d00011b","treeId":"655a38b74450703f0b0004a4","seq":16819606,"position":1,"parentId":"63766a595d0fbe476c0001c3","content":"For example, here are some selections from [an article on emergency preparedness](https://arstechnica.com/gadgets/2016/06/when-everything-else-fails-amateur-radio-will-still-be-there-and-thriving/)."},{"_id":"6375ac485d0fbe476c0001ce","treeId":"655a38b74450703f0b0004a4","seq":16819602,"position":0.5,"parentId":"653c9957e8acad334d00011b","content":">Radio amateurs get a sweet deal, with effectively free access to many gigahertz of the same radio spectrum that companies pay billions for."},{"_id":"653c8921e8acad334d00011c","treeId":"655a38b74450703f0b0004a4","seq":16511678,"position":1,"parentId":"653c9957e8acad334d00011b","content":"> Then, there's backup. Take [the European HAMNET](https://www.tapr.org/pdf/DCC2014-TheEuropeanHAMNET-DG8NGN.pdf), 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](http://arstechnica.co.uk/information-technology/2016/05/how-the-internet-works-submarine-cables-data-centres-last-mile/)---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. These days it can even be a full-fat digital medium."},{"_id":"637668b25d0fbe476c0001c5","treeId":"655a38b74450703f0b0004a4","seq":16818475,"position":1.5,"parentId":"63766c315d0fbe476c0001c2","content":"in-between\n* experimentation\n* building: receivers, transmitters, instruments, antennas, repeater networks, solar power, computer systems and networks..."},{"_id":"63766a055d0fbe476c0001c4","treeId":"655a38b74450703f0b0004a4","seq":16819722,"position":2,"parentId":"63766c315d0fbe476c0001c2","content":"fun communications\n* exploration - DXing, etc\n* rag-chewing\n* contesting\n* competitive direction-finding (AKA fox hunting)"},{"_id":"6374cc48a4889556960001db","treeId":"655a38b74450703f0b0004a4","seq":16887056,"position":0.3125,"parentId":"63766e605d0fbe476c0001c0","content":"### **Q&A**\nGet to know the class. Interests, education, background."},{"_id":"6372140553b88b9b460001e7","treeId":"655a38b74450703f0b0004a4","seq":16887058,"position":1,"parentId":"6374cc48a4889556960001db","content":"* Questions from the class?\n* How many of you are nerds? Eggheads?Tinkerers? How many of you are preppers? How many of you are gearheads, weekend warriors, mall ninjas? To what extent do you identify with the word \"tacticool\"??\n* Intent to pass the exam?\n* Interest in morse code?\n* Interest in soldering?"},{"_id":"6376600d5d0fbe476c0001c7","treeId":"655a38b74450703f0b0004a4","seq":17336268,"position":0.375,"parentId":"63766e605d0fbe476c0001c0","content":"### **Administrivia: Sign-up, distribute books**"},{"_id":"636872ab53b88b9b46000391","treeId":"655a38b74450703f0b0004a4","seq":16830516,"position":1,"parentId":"6376600d5d0fbe476c0001c7","content":"[ ] collect contact information"},{"_id":"63640e71d532bf36e8000222","treeId":"655a38b74450703f0b0004a4","seq":16834575,"position":1.5,"parentId":"6376600d5d0fbe476c0001c7","content":"[ ] scheduling preference"},{"_id":"6368723253b88b9b46000392","treeId":"655a38b74450703f0b0004a4","seq":16830515,"position":2,"parentId":"6376600d5d0fbe476c0001c7","content":"[ ] show people course outline, test on phones"},{"_id":"636830fd53b88b9b460003a1","treeId":"655a38b74450703f0b0004a4","seq":16830514,"position":3,"parentId":"6376600d5d0fbe476c0001c7","content":"[ ] include brochures in book"},{"_id":"63766c5a5d0fbe476c0001c1","treeId":"655a38b74450703f0b0004a4","seq":16833521,"position":0.5,"parentId":"63766e605d0fbe476c0001c0","content":"### **Demonstrations: What you can do on the radio**"},{"_id":"637622ac5d0fbe476c0001ca","treeId":"655a38b74450703f0b0004a4","seq":16895364,"position":1,"parentId":"63766c5a5d0fbe476c0001c1","content":"In the Bulkley Valley:\n* talk or listen to the repeater network\n* HF comms around the world using various modes and systems\n* help out with BV search and rescue\n* help build and maintain the repeater network. (We just linked to Terrace, next stop is Prince Rupert!)\n* comms for triathlons, trade show -- good practice for emergencies!"},{"_id":"637592945d0fbe476c0001d2","treeId":"655a38b74450703f0b0004a4","seq":16834598,"position":0.25,"parentId":"637622ac5d0fbe476c0001ca","content":"Here is an overview of [the northern BC repeater network](http://www.pgarc.org/documents/nbc_map.pdf). "},{"_id":"63752ee85d0fbe476c0001da","treeId":"655a38b74450703f0b0004a4","seq":16820567,"position":2,"parentId":"637622ac5d0fbe476c0001ca","content":"Here is a video of somebody [operating using morse code](https://www.youtube.com/watch?v=GvQ_UnePS7w)"},{"_id":"6332e97f4ac6fd176200074f","treeId":"655a38b74450703f0b0004a4","seq":16887061,"position":1.25,"parentId":"63766c5a5d0fbe476c0001c1","content":"[ ] HF station"},{"_id":"6332e93d4ac6fd1762000750","treeId":"655a38b74450703f0b0004a4","seq":16887065,"position":1.375,"parentId":"63766c5a5d0fbe476c0001c1","content":"[ ] crystal radio"},{"_id":"63638c07d532bf36e8000224","treeId":"655a38b74450703f0b0004a4","seq":16887063,"position":1.5,"parentId":"63766c5a5d0fbe476c0001c1","content":"[ ] IRLP demo"},{"_id":"63636589d532bf36e8000225","treeId":"655a38b74450703f0b0004a4","seq":16887064,"position":1.75,"parentId":"63766c5a5d0fbe476c0001c1","content":"[ ] Winlink demo"},{"_id":"63759d5d5d0fbe476c0001d1","treeId":"655a38b74450703f0b0004a4","seq":16819895,"position":3,"parentId":"63766c5a5d0fbe476c0001c1","content":"Building:\n\nOnce upon a time, people commonly built radios out of household parts! Here is [an old book that deals with that sort of thing](http://www.learnmorsecode.com/regen/Radio-News-Wrinkles-1926.pdf).\n\nIt is still possible to build a radio out of common parts, and we will do this beginning roughly in class two or three."},{"_id":"637660395d0fbe476c0001c6","treeId":"655a38b74450703f0b0004a4","seq":16895203,"position":2,"parentId":"63766e605d0fbe476c0001c0","content":"### **Homework!**\nStart reading the book\nWatch some videos\nRead some links\nTry a quiz"},{"_id":"6368249153b88b9b460003a3","treeId":"655a38b74450703f0b0004a4","seq":16833638,"position":0.0625,"parentId":"637660395d0fbe476c0001c6","content":"Book: (to be confirmed)\n* read Chapter 1\n* read Chapter 5 to section 5. Stop at section 6.\n* read or skim as much of Chapter 2 as you are interested in, \n* read or skim Appendix 1 sections 1 to 5, if you're feeling ambitious"},{"_id":"6368810353b88b9b4600038c","treeId":"655a38b74450703f0b0004a4","seq":16921221,"position":0.1875,"parentId":"637660395d0fbe476c0001c6","content":"Links:\n* [login to student success pages](https://www.coaxpublications.ca/rsp0001.php)\n* [NATO phonetic alphabet](https://en.wikipedia.org/wiki/NATO_phonetic_alphabet)\n\n* [available call signs](https://apc-cap.ic.gc.ca/pls/apc_anon/query_avail_cs$.startup)"},{"_id":"63681bbb53b88b9b460003a6","treeId":"655a38b74450703f0b0004a4","seq":16831082,"position":0.375,"parentId":"637660395d0fbe476c0001c6","content":"Quiz:\nUse the class Access Code to quiz themselves on Chapter 2."},{"_id":"63681ade53b88b9b460003a7","treeId":"655a38b74450703f0b0004a4","seq":16831080,"position":1,"parentId":"63681bbb53b88b9b460003a6","content":"Try as many chapter quizzes as you wish"},{"_id":"63681a3853b88b9b460003a9","treeId":"655a38b74450703f0b0004a4","seq":16830631,"position":2,"parentId":"63681bbb53b88b9b460003a6","content":"Make a note of any questions that caused problems, and:\n* review relevant parts of the chapter\n* bring questions to next class"},{"_id":"632656bac82956ebf200022d","treeId":"655a38b74450703f0b0004a4","seq":16895239,"position":0.46875,"parentId":"637660395d0fbe476c0001c6","content":"Videos:\n* [the brits do it better](https://www.youtube.com/watch?v=8x6x_6mDVlQ)"},{"_id":"6368780153b88b9b4600038e","treeId":"655a38b74450703f0b0004a4","seq":16921728,"position":0.8125,"parentId":"654fb37b305a6842700000cf","content":"## Class 2: Basic Electricity"},{"_id":"63264553c82956ebf2000231","treeId":"655a38b74450703f0b0004a4","seq":16895370,"position":2.5,"parentId":"6368780153b88b9b4600038e","content":"In the first class, we introduced about the electromagnetic spectrum..."},{"_id":"63263c4bc82956ebf2000232","treeId":"655a38b74450703f0b0004a4","seq":16895371,"position":2.75,"parentId":"6368780153b88b9b4600038e","content":"What are radio waves made from?"},{"_id":"63263bcec82956ebf2000233","treeId":"655a38b74450703f0b0004a4","seq":16915462,"position":1,"parentId":"63263c4bc82956ebf2000232","content":"Some acceptable answers: electricity, magnetism"},{"_id":"63258f82c82956ebf2000248","treeId":"655a38b74450703f0b0004a4","seq":16895885,"position":1,"parentId":"63263bcec82956ebf2000233","content":"both are correct"},{"_id":"63258e8bc82956ebf2000249","treeId":"655a38b74450703f0b0004a4","seq":16895888,"position":1.5,"parentId":"63263c4bc82956ebf2000232","content":"what is electricity made from?"},{"_id":"63258e03c82956ebf200024b","treeId":"655a38b74450703f0b0004a4","seq":16895893,"position":1,"parentId":"63258e8bc82956ebf2000249","content":"acceptable answers: electrons, electric fields"},{"_id":"63258e41c82956ebf200024a","treeId":"655a38b74450703f0b0004a4","seq":16895890,"position":1.75,"parentId":"63263c4bc82956ebf2000232","content":"what is magnetism made from?"},{"_id":"63258cdec82956ebf200024c","treeId":"655a38b74450703f0b0004a4","seq":16915446,"position":1,"parentId":"63258e41c82956ebf200024a","content":"[magic & miracles](https://www.youtube.com/watch?v=8bhYMnHb5JY)\n\nseriously though, we'll get to magnetics later"},{"_id":"632638a5c82956ebf2000234","treeId":"655a38b74450703f0b0004a4","seq":16895556,"position":2,"parentId":"63263c4bc82956ebf2000232","content":"so basically, part of the technical content of the course is about electromagnetism, which governs feedlines, antennas, propagation, etc"},{"_id":"6325977cc82956ebf2000247","treeId":"655a38b74450703f0b0004a4","seq":16915304,"position":1,"parentId":"632638a5c82956ebf2000234","content":"but it's too early to talk much about electromagnetism right now"},{"_id":"631848158d2f4d9bea000783","treeId":"655a38b74450703f0b0004a4","seq":16915315,"position":2.5,"parentId":"63263c4bc82956ebf2000232","content":"we have to talk about electricity first"},{"_id":"6318474f8d2f4d9bea000784","treeId":"655a38b74450703f0b0004a4","seq":16915327,"position":2.75,"parentId":"63263c4bc82956ebf2000232","content":"two obvious places to start: wall outlets, and batteries"},{"_id":"6325bae0c82956ebf2000239","treeId":"655a38b74450703f0b0004a4","seq":17032594,"position":3.1875,"parentId":"6368780153b88b9b4600038e","content":"### **Basic Electricity**"},{"_id":"631840ad8d2f4d9bea000785","treeId":"655a38b74450703f0b0004a4","seq":16915401,"position":0.28125,"parentId":"6325bae0c82956ebf2000239","content":"Okay, so we established that electricity has *something* to do with electrons and fields"},{"_id":"6317fd70d1bfa6b5a2000794","treeId":"655a38b74450703f0b0004a4","seq":16915804,"position":0.421875,"parentId":"6325bae0c82956ebf2000239","content":"electricity-water analogy"},{"_id":"6317fc6ed1bfa6b5a2000796","treeId":"655a38b74450703f0b0004a4","seq":16915818,"position":2,"parentId":"6317fd70d1bfa6b5a2000794","content":"analogy between voltage and static pressure"},{"_id":"6317fbb4d1bfa6b5a2000797","treeId":"655a38b74450703f0b0004a4","seq":16915819,"position":3,"parentId":"6317fd70d1bfa6b5a2000794","content":"analogy between speed and current "},{"_id":"6317f8dfd1bfa6b5a200079b","treeId":"655a38b74450703f0b0004a4","seq":16915824,"position":5,"parentId":"6317fd70d1bfa6b5a2000794","content":"analogy between resistance and friction"},{"_id":"6317f98ad1bfa6b5a2000798","treeId":"655a38b74450703f0b0004a4","seq":16915826,"position":6,"parentId":"6317fd70d1bfa6b5a2000794","content":"analogy between power and flow rate"},{"_id":"6325b64cc82956ebf200023d","treeId":"655a38b74450703f0b0004a4","seq":16915290,"position":0.5625,"parentId":"6325bae0c82956ebf2000239","content":"voltage"},{"_id":"63182daf8d2f4d9bea00092d","treeId":"655a38b74450703f0b0004a4","seq":16915836,"position":0.6328125,"parentId":"6325bae0c82956ebf2000239","content":"current"},{"_id":"6325b5fcc82956ebf200023f","treeId":"655a38b74450703f0b0004a4","seq":16921612,"position":3,"parentId":"6325bae0c82956ebf2000239","content":"single resistors: Ohm's law"},{"_id":"6313db2307d2338c22000275","treeId":"655a38b74450703f0b0004a4","seq":16921530,"position":3.125,"parentId":"6325bae0c82956ebf2000239","content":"resistors in parallel"},{"_id":"6313dafa07d2338c22000276","treeId":"655a38b74450703f0b0004a4","seq":16921531,"position":3.1875,"parentId":"6325bae0c82956ebf2000239","content":"resistors in series"},{"_id":"6313dea807d2338c22000273","treeId":"655a38b74450703f0b0004a4","seq":16921037,"position":3.5,"parentId":"6325bae0c82956ebf2000239","content":"voltage dividers"},{"_id":"63322ce14ac6fd1762000756","treeId":"655a38b74450703f0b0004a4","seq":16920736,"position":3.625,"parentId":"6368780153b88b9b4600038e","content":"### **Administrivia**\n\n[ ] ask about emails - Justin's to be corrected, Edward's to be added, John's to be added\n[ ] follow up on payment"},{"_id":"632657dcc82956ebf200022c","treeId":"655a38b74450703f0b0004a4","seq":16921540,"position":3.75,"parentId":"6368780153b88b9b4600038e","content":"### **Homework**\nRead the book, watch some videos"},{"_id":"6313ea0907d2338c22000270","treeId":"655a38b74450703f0b0004a4","seq":16921620,"position":0.078125,"parentId":"632657dcc82956ebf200022c","content":"Book:\n\n[ ] Read to end of chapter 3\n[ ] Appendix 1, section 5(?) on **SI units** and **metric prefixes**"},{"_id":"63143a2707d2338c2200026f","treeId":"655a38b74450703f0b0004a4","seq":16921621,"position":0.09375,"parentId":"632657dcc82956ebf200022c","content":"Videos"},{"_id":"6318511a8d2f4d9bea00077f","treeId":"655a38b74450703f0b0004a4","seq":17032521,"position":0.125,"parentId":"63143a2707d2338c2200026f","content":"Watch [this video on Ohm's Law](https://www.youtube.com/watch?v=CztiI0re5Eo), or another like it."},{"_id":"62b6d4f6a7ef3106690007f3","treeId":"655a38b74450703f0b0004a4","seq":17032523,"position":0.1875,"parentId":"63143a2707d2338c2200026f","content":"[old training video on series and parallel resistors](https://www.youtube.com/watch?v=ajtwQRmJajk&list=PLvplkb-chocV8788-jlgxKyTItOtyQTTE&index=7&t=0s)"},{"_id":"631825768d2f4d9bea00092f","treeId":"655a38b74450703f0b0004a4","seq":16921554,"position":0.25,"parentId":"63143a2707d2338c2200026f","content":"[video on voltage and current in various circuits](https://www.youtube.com/watch?v=m4jzgqZu-4s)"},{"_id":"6317e9a107d2338c2200026c","treeId":"655a38b74450703f0b0004a4","seq":16921552,"position":0.5,"parentId":"63143a2707d2338c2200026f","content":"[ohm's law practical demo](https://youtu.be/GP-KWqKvv9I?t=118)"},{"_id":"6317e23b07d2338c2200026d","treeId":"655a38b74450703f0b0004a4","seq":16920950,"position":1,"parentId":"63143a2707d2338c2200026f","content":"[voltage dividers](https://www.youtube.com/watch?v=pfoFQcdKoLw)"},{"_id":"63184f1f8d2f4d9bea000780","treeId":"655a38b74450703f0b0004a4","seq":16920954,"position":5,"parentId":"63143a2707d2338c2200026f","content":"Optional: waste lot of time by watching videos from [this channel about physics](https://www.youtube.com/channel/UCYrX5FiWjiPd0JytMh6NX1Q)"},{"_id":"63686bec53b88b9b46000395","treeId":"655a38b74450703f0b0004a4","seq":17031977,"position":0.859375,"parentId":"654fb37b305a6842700000cf","content":"## Class 3: Basic Electricity, part 2. "},{"_id":"62b6a20a4656ed1a610002d0","treeId":"655a38b74450703f0b0004a4","seq":17032595,"position":0.34375,"parentId":"63686bec53b88b9b46000395","content":"### **Basic Electricity**"},{"_id":"6313e98907d2338c22000271","treeId":"655a38b74450703f0b0004a4","seq":17031019,"position":0.375,"parentId":"63686bec53b88b9b46000395","content":"Conclusion of basic electricity part 1: DC power"},{"_id":"62f8885a118b358153000296","treeId":"655a38b74450703f0b0004a4","seq":17031022,"position":0.5,"parentId":"6313e98907d2338c22000271","content":"theory and definition of electric power\n\npower = current * voltage"},{"_id":"62c6f6653ed807f8e00002a8","treeId":"655a38b74450703f0b0004a4","seq":17010618,"position":1,"parentId":"62f8885a118b358153000296","content":"units of energy (work-energy theorem)\n1 joule = 1 coulomb volt\n1 joule = 1 newton meter"},{"_id":"62c6f62e3ed807f8e00002a9","treeId":"655a38b74450703f0b0004a4","seq":17010612,"position":2,"parentId":"62f8885a118b358153000296","content":"units of power\njoules / second"},{"_id":"62c6f60c3ed807f8e00002aa","treeId":"655a38b74450703f0b0004a4","seq":17010613,"position":3,"parentId":"62f8885a118b358153000296","content":"units of current\ncoulomb / second"},{"_id":"62c6f5353ed807f8e00002ac","treeId":"655a38b74450703f0b0004a4","seq":17010630,"position":4,"parentId":"62f8885a118b358153000296","content":"units of voltage\npotential energy per charge"},{"_id":"62b6f695a7ef3106690007ed","treeId":"655a38b74450703f0b0004a4","seq":17032446,"position":4.5,"parentId":"62f8885a118b358153000296","content":"analogy between masses in gravitational field, and charges in an electric field"},{"_id":"643ba4cb9a6363517200070b","treeId":"655a38b74450703f0b0004a4","seq":17032597,"position":5,"parentId":"62f8885a118b358153000296","content":"This site talks about [electrical-mechanical analogies](http://lpsa.swarthmore.edu/Analogs/ElectricalMechanicalAnalogs.html) in quite a lot of detail, far too much detail to be of use really"},{"_id":"62c674323ed807f8e00002af","treeId":"655a38b74450703f0b0004a4","seq":17032200,"position":0.5625,"parentId":"6313e98907d2338c22000271","content":"power in a resistor"},{"_id":"62bac0ce3ed807f8e00002b3","treeId":"655a38b74450703f0b0004a4","seq":17032198,"position":0.625,"parentId":"6313e98907d2338c22000271","content":"(nope) **demo:** current and voltage through a lightbulb"},{"_id":"630c289f118b358153000280","treeId":"655a38b74450703f0b0004a4","seq":17032202,"position":1,"parentId":"6313e98907d2338c22000271","content":"(nope) demo:\npower in resistors, using resistance and current measurements (in series and parallel?)"},{"_id":"6325cf03c82956ebf2000235","treeId":"655a38b74450703f0b0004a4","seq":16964265,"position":0.5,"parentId":"63686bec53b88b9b46000395","content":"Basic electricity, part 2: alternating current"},{"_id":"6313d6dc07d2338c22000278","treeId":"655a38b74450703f0b0004a4","seq":16964256,"position":0.5,"parentId":"6325cf03c82956ebf2000235","content":"bicycle-chain model of current in a circuit: AC vs DC"},{"_id":"6325cc92c82956ebf2000238","treeId":"655a38b74450703f0b0004a4","seq":16895658,"position":1,"parentId":"6325cf03c82956ebf2000235","content":"household outlets - AC"},{"_id":"62f88e7e118b358153000292","treeId":"655a38b74450703f0b0004a4","seq":17032574,"position":1,"parentId":"6325cc92c82956ebf2000238","content":"[ ] oscilloscope demo: measuring peak voltage, frequency"},{"_id":"62f89b80118b35815300028d","treeId":"655a38b74450703f0b0004a4","seq":16964289,"position":2.5,"parentId":"6325cf03c82956ebf2000235","content":"AC power"},{"_id":"62f89949118b35815300028e","treeId":"655a38b74450703f0b0004a4","seq":16964262,"position":1,"parentId":"62f89b80118b35815300028d","content":"power: peak voltage, RMS voltage, peak current, RMS current"},{"_id":"62f895b7118b35815300028f","treeId":"655a38b74450703f0b0004a4","seq":16964263,"position":2,"parentId":"62f89b80118b35815300028d","content":"a bit of calculus for the high-school students"},{"_id":"62c4820f3ed807f8e00002b0","treeId":"655a38b74450703f0b0004a4","seq":17032207,"position":3,"parentId":"62f89b80118b35815300028d","content":"why 60 Hz? [wikipedia](https://en.wikipedia.org/wiki/Utility_frequency)\n\nOf interest is the 400 Hz hum of aircraft. [mains hum](https://en.wikipedia.org/wiki/Mains_hum)"},{"_id":"6325b9fdc82956ebf200023b","treeId":"655a38b74450703f0b0004a4","seq":17032577,"position":3,"parentId":"6325cf03c82956ebf2000235","content":"whistling into a mic and putting the result on a scope: Teasing what's to come"},{"_id":"63182f2d8d2f4d9bea00092b","treeId":"655a38b74450703f0b0004a4","seq":17032302,"position":2.5,"parentId":"63686bec53b88b9b46000395","content":"### **Homework**\nWatch some videos, read the book."},{"_id":"62b71d15a7ef3106690007e7","treeId":"655a38b74450703f0b0004a4","seq":17032355,"position":1,"parentId":"63182f2d8d2f4d9bea00092b","content":"**Reading:**\n\nEverything up to chapter 3, thoroughly.\nChapter 4, skimmed.\nChapter 5, thoroughly."},{"_id":"62b7128fa7ef3106690007e9","treeId":"655a38b74450703f0b0004a4","seq":17032353,"position":1.5,"parentId":"63182f2d8d2f4d9bea00092b","content":"**Videos:**"},{"_id":"62b71285a7ef3106690007ea","treeId":"655a38b74450703f0b0004a4","seq":17032371,"position":1.75,"parentId":"63182f2d8d2f4d9bea00092b","content":"First, [this excellent 50s training video](https://www.youtube.com/watch?v=q-DKc4KHPqU) with great animations. Can't recommend highly enough. As one of the YouTube commenters said, \"OLD IS GOLD.\""},{"_id":"62b6dbe6a7ef3106690007f1","treeId":"655a38b74450703f0b0004a4","seq":17032497,"position":1.8125,"parentId":"63182f2d8d2f4d9bea00092b","content":"In the same vein, [old training video on power](https://www.youtube.com/watch?v=l0QLZGpFol8&list=PLvplkb-chocV8788-jlgxKyTItOtyQTTE&index=2&t=0s)"},{"_id":"62b70825a7ef3106690007eb","treeId":"655a38b74450703f0b0004a4","seq":17032380,"position":1.875,"parentId":"63182f2d8d2f4d9bea00092b","content":"A decent video on [RMS voltage and current](https://www.youtube.com/watch?v=ERIToctYUcQ)"},{"_id":"62b6f4d7a7ef3106690007ef","treeId":"655a38b74450703f0b0004a4","seq":17032562,"position":1.9375,"parentId":"63182f2d8d2f4d9bea00092b","content":"Entertaining video on [practical differences between DC and AC power: A human perspective](https://www.youtube.com/watch?v=hp97GjuULX8)"},{"_id":"62b6f1f1a7ef3106690007f0","treeId":"655a38b74450703f0b0004a4","seq":17088887,"position":1,"parentId":"62b6f4d7a7ef3106690007ef","content":"[(the part where it starts to get good)](https://youtu.be/hp97GjuULX8?t=112)"},{"_id":"62b6bb9b4656ed1a610002cf","treeId":"655a38b74450703f0b0004a4","seq":17032566,"position":1.96875,"parentId":"63182f2d8d2f4d9bea00092b","content":"[more in the same vein](https://www.youtube.com/watch?v=n2iPFZWe7uk)\n\n[and more, on volts and amps](https://www.youtube.com/watch?v=iyG9_UFJVoI)"},{"_id":"62b71bf1a7ef3106690007e8","treeId":"655a38b74450703f0b0004a4","seq":17032363,"position":2,"parentId":"63182f2d8d2f4d9bea00092b","content":"For much more detail, [this long video on basic electricity](https://www.youtube.com/watch?v=F_5sV8s9ZEA), and [its long sequel](https://www.youtube.com/watch?v=naTnyUMtPhs). Both explain the same concepts dealt with in class 3."},{"_id":"63131420118b35815300027a","treeId":"655a38b74450703f0b0004a4","seq":17107204,"position":0.865234375,"parentId":"654fb37b305a6842700000cf","content":"## Class 4: Electromagnetism, EM Waves, and EM components."},{"_id":"62625717001682e70f000359","treeId":"655a38b74450703f0b0004a4","seq":17116135,"position":0.0625,"parentId":"63131420118b35815300027a","content":"### Review up to now\n* we talked about electricity and batteries. We dealt with the concepts of voltage, current, and resistance.\n* we talked about electricity and wall outlets, and talked about power. We looked at AC waveforms. We talked about AC power and resistors.\n\nIn 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."},{"_id":"6325af46c82956ebf2000244","treeId":"655a38b74450703f0b0004a4","seq":17032691,"position":0.125,"parentId":"63131420118b35815300027a","content":"Beginning electromagnetism: current in a wire, and consequences thereof"},{"_id":"62b662ea6d1f079e170002d2","treeId":"655a38b74450703f0b0004a4","seq":17032693,"position":0.25,"parentId":"6325af46c82956ebf2000244","content":"As quickly as possible...."},{"_id":"63183ef18d2f4d9bea000788","treeId":"655a38b74450703f0b0004a4","seq":17104782,"position":0.28125,"parentId":"6325af46c82956ebf2000244","content":"[ ] neon lamp demo"},{"_id":"626b112e001682e70f0002fc","treeId":"655a38b74450703f0b0004a4","seq":17104783,"position":2,"parentId":"63183ef18d2f4d9bea000788","content":"why? Why not. Let's talk about what's happening."},{"_id":"6283057bce7078a17d0003f3","treeId":"655a38b74450703f0b0004a4","seq":17088936,"position":0.3125,"parentId":"6325af46c82956ebf2000244","content":"electric fields"},{"_id":"6283053bce7078a17d0003f4","treeId":"655a38b74450703f0b0004a4","seq":17088941,"position":0.5,"parentId":"6283057bce7078a17d0003f3","content":"The concept of a field refers to a tendency of a particle to experience a force that varies with position."},{"_id":"6283037bce7078a17d0003f5","treeId":"655a38b74450703f0b0004a4","seq":17088939,"position":0.75,"parentId":"6283057bce7078a17d0003f3","content":"In a gravitational field, the field acts on particles with mass. In an electric field, it acts on particles with electric charge."},{"_id":"6283066dce7078a17d0003f2","treeId":"655a38b74450703f0b0004a4","seq":17088942,"position":1,"parentId":"6283057bce7078a17d0003f3","content":"The presence of a voltage between two points creates an electric field."},{"_id":"626a2b5e001682e70f000303","treeId":"655a38b74450703f0b0004a4","seq":17106302,"position":2,"parentId":"6283057bce7078a17d0003f3","content":"Static charges create static fields.\n\nSteadily moving charges create static fields, and static magnetic fields.\n\nBetween static charges and moving charges, the charge must accelerate. Accelerating charges create changing fields."},{"_id":"626a2773001682e70f000304","treeId":"655a38b74450703f0b0004a4","seq":17106303,"position":2.5,"parentId":"6283057bce7078a17d0003f3","content":"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."},{"_id":"626a2554001682e70f000305","treeId":"655a38b74450703f0b0004a4","seq":17106307,"position":2.75,"parentId":"6283057bce7078a17d0003f3","content":"Anyway, don't dwell on this; just show the video:"},{"_id":"626a2f90001682e70f000302","treeId":"655a38b74450703f0b0004a4","seq":17106301,"position":3,"parentId":"6283057bce7078a17d0003f3","content":"[changing field from a charge](https://www.youtube.com/watch?v=pcVbnhwn9Jw)"},{"_id":"6325b4b1c82956ebf2000240","treeId":"655a38b74450703f0b0004a4","seq":17032692,"position":0.5,"parentId":"6325af46c82956ebf2000244","content":"DC current in a wire"},{"_id":"628306ffce7078a17d0003f1","treeId":"655a38b74450703f0b0004a4","seq":17106310,"position":1,"parentId":"6325b4b1c82956ebf2000240","content":"Steady current in a wire creates a magnetic field."},{"_id":"626a1611001682e70f000306","treeId":"655a38b74450703f0b0004a4","seq":17106336,"position":1.5,"parentId":"6325b4b1c82956ebf2000240","content":"steady currents are boring"},{"_id":"62830050ce7078a17d0003f6","treeId":"655a38b74450703f0b0004a4","seq":17104912,"position":2,"parentId":"6325b4b1c82956ebf2000240","content":"What happens when we go from no current to some current? That is, what happens when the current **changes**?"},{"_id":"6267113b001682e70f000343","treeId":"655a38b74450703f0b0004a4","seq":17107345,"position":0.75,"parentId":"6325af46c82956ebf2000244","content":"[illustrations of the following topics](https://www.wyzant.com/resources/lessons/science/physics/magnetism)"},{"_id":"6325b432c82956ebf2000241","treeId":"655a38b74450703f0b0004a4","seq":16915214,"position":1,"parentId":"6325af46c82956ebf2000244","content":"electric field around a wire"},{"_id":"63259e4bc82956ebf2000246","treeId":"655a38b74450703f0b0004a4","seq":16895799,"position":1,"parentId":"6325b432c82956ebf2000241","content":"electric field between two plates"},{"_id":"631857638d2f4d9bea00077a","treeId":"655a38b74450703f0b0004a4","seq":16915219,"position":2,"parentId":"6325af46c82956ebf2000244","content":"magnetic field around a wire"},{"_id":"6317ff66d1bfa6b5a2000791","treeId":"655a38b74450703f0b0004a4","seq":16915788,"position":1,"parentId":"631857638d2f4d9bea00077a","content":"https://www.youtube.com/watch?v=tKxFLH2Nhe4"},{"_id":"631857158d2f4d9bea00077b","treeId":"655a38b74450703f0b0004a4","seq":16915221,"position":3,"parentId":"6325af46c82956ebf2000244","content":"changing current in a wire"},{"_id":"626b0f3e001682e70f0002fe","treeId":"655a38b74450703f0b0004a4","seq":17104787,"position":3,"parentId":"631857158d2f4d9bea00077b","content":"accelerating electrons, consequences thereof"},{"_id":"625c8c23a2fdf0bb650004ad","treeId":"655a38b74450703f0b0004a4","seq":17116343,"position":4,"parentId":"631857158d2f4d9bea00077b","content":"switched dc current, consequences thereof"},{"_id":"631839768d2f4d9bea000789","treeId":"655a38b74450703f0b0004a4","seq":17031992,"position":0.1875,"parentId":"63131420118b35815300027a","content":"Electromagnetic waves"},{"_id":"62b756dfa7ef3106690007da","treeId":"655a38b74450703f0b0004a4","seq":17089061,"position":0.25,"parentId":"631839768d2f4d9bea000789","content":"spark-gap transmitter"},{"_id":"62824bbfce7078a17d0003f9","treeId":"655a38b74450703f0b0004a4","seq":17106532,"position":1,"parentId":"62b756dfa7ef3106690007da","content":"[dielectric breakdown strength of air]\n\n[spark gaps](https://en.wikipedia.org/wiki/Spark_gap)\n\n> Air breaks down at about 30 kV/cm,[5] depending on humidity,"},{"_id":"6282446ace7078a17d0003ff","treeId":"655a38b74450703f0b0004a4","seq":17106759,"position":2,"parentId":"62b756dfa7ef3106690007da","content":"[ ] talk about dielectrics, and by extension, conductors, insulators, semiconductors"},{"_id":"626723a8001682e70f000340","treeId":"655a38b74450703f0b0004a4","seq":17107323,"position":3,"parentId":"62b756dfa7ef3106690007da","content":"[nice images of early spark gap transmitters](https://www.researchgate.net/figure/a-Scheme-of-Hertz-experimental-set-up-b-Nikola-Teslas-spark-gap-transmitter_fig2_236970713)"},{"_id":"625430e21babf99d1e000352","treeId":"655a38b74450703f0b0004a4","seq":17127509,"position":4,"parentId":"62b756dfa7ef3106690007da","content":"[this page shows the frequency spectrum of an impulse](http://www.azimadli.com/vibman/examplesofsomewaveformsandtheirspectra.htm). 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](http://www001.upp.so-net.ne.jp/imagetec/engimgtec/engimgtec6.html)"},{"_id":"62f88b52118b358153000293","treeId":"655a38b74450703f0b0004a4","seq":16964291,"position":0.5,"parentId":"631839768d2f4d9bea000789","content":"nature of electromagnetic waves"},{"_id":"630bea8e118b358153000285","treeId":"655a38b74450703f0b0004a4","seq":17031656,"position":2,"parentId":"62f88b52118b358153000293","content":"sound is a wave that propagates in a physical medium"},{"_id":"62b973be2933f83f040002b3","treeId":"655a38b74450703f0b0004a4","seq":17031657,"position":2.5,"parentId":"62f88b52118b358153000293","content":"em waves are a means of describing how energy propagates through the pervasive medium of the electric and magnetic fields"},{"_id":"6262bcd3001682e70f000353","treeId":"655a38b74450703f0b0004a4","seq":17110407,"position":2.75,"parentId":"62f88b52118b358153000293","content":"These fields can be thought of as separate, but they're really manifestations of the same thing seen from different directions."},{"_id":"630be870118b358153000286","treeId":"655a38b74450703f0b0004a4","seq":17089020,"position":3,"parentId":"62f88b52118b358153000293","content":"em waves are said to \"self-propagate\""},{"_id":"6441c2299a63635172000708","treeId":"655a38b74450703f0b0004a4","seq":17031651,"position":1,"parentId":"630be870118b358153000286","content":"http://www.tapir.caltech.edu/~teviet/Waves/emfield.html"},{"_id":"625d7167b251a8269f000350","treeId":"655a38b74450703f0b0004a4","seq":17115762,"position":4,"parentId":"62f88b52118b358153000293","content":"https://www.wyzant.com/resources/lessons/science/physics/magnetism"},{"_id":"631315c8118b358153000279","treeId":"655a38b74450703f0b0004a4","seq":16964303,"position":5,"parentId":"631839768d2f4d9bea000789","content":"properties of waves"},{"_id":"62f88a3f118b358153000294","treeId":"655a38b74450703f0b0004a4","seq":17106761,"position":1,"parentId":"631315c8118b358153000279","content":"[ ] relation between speed, frequency, and wavelength"},{"_id":"630be7a4118b358153000287","treeId":"655a38b74450703f0b0004a4","seq":17031654,"position":2,"parentId":"631315c8118b358153000279","content":"in free space, the waves diminish as they disperse, as a consequence of this self-propagation"},{"_id":"6268f1b6001682e70f000308","treeId":"655a38b74450703f0b0004a4","seq":17106766,"position":7,"parentId":"631839768d2f4d9bea000789","content":"[ ] show decaying oscillation in primary"},{"_id":"6268f0ff001682e70f000309","treeId":"655a38b74450703f0b0004a4","seq":17106769,"position":8,"parentId":"631839768d2f4d9bea000789","content":"[ ] show transmitted waves on scope"},{"_id":"6268f079001682e70f00030b","treeId":"655a38b74450703f0b0004a4","seq":17106774,"position":9,"parentId":"631839768d2f4d9bea000789","content":"[ ] listen to noise on shortwave receiver"},{"_id":"62823cd4ce7078a17d000402","treeId":"655a38b74450703f0b0004a4","seq":17106574,"position":0.21875,"parentId":"63131420118b35815300027a","content":"inductors, an introduction"},{"_id":"6268bb78001682e70f00030f","treeId":"655a38b74450703f0b0004a4","seq":17106801,"position":0.5,"parentId":"62823cd4ce7078a17d000402","content":"okay, the spark gap transmitter is based on inductors, so let's talk about inductors."},{"_id":"6268b7b8001682e70f000310","treeId":"655a38b74450703f0b0004a4","seq":17106804,"position":1,"parentId":"6268bb78001682e70f00030f","content":"an inductor is a component that stores energy in a magnetic field."},{"_id":"6268b623001682e70f000311","treeId":"655a38b74450703f0b0004a4","seq":17106816,"position":2,"parentId":"6268bb78001682e70f00030f","content":"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."},{"_id":"6268a557001682e70f000312","treeId":"655a38b74450703f0b0004a4","seq":17106818,"position":3,"parentId":"6268bb78001682e70f00030f","content":"In the case of a lone inductor, this is called back-EMF..."},{"_id":"6268a3c3001682e70f000314","treeId":"655a38b74450703f0b0004a4","seq":17106822,"position":3.5,"parentId":"6268bb78001682e70f00030f","content":"A transformer consists of two inductors side by side. The magnetic fields of both coils affect the current in the other."},{"_id":"6268a430001682e70f000313","treeId":"655a38b74450703f0b0004a4","seq":17106823,"position":4,"parentId":"6268bb78001682e70f00030f","content":"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."},{"_id":"628239e4ce7078a17d000404","treeId":"655a38b74450703f0b0004a4","seq":17089106,"position":1,"parentId":"62823cd4ce7078a17d000402","content":"inductors and fields"},{"_id":"62683b89001682e70f00031e","treeId":"655a38b74450703f0b0004a4","seq":17106899,"position":1,"parentId":"628239e4ce7078a17d000404","content":"the magnetic field in an inductor is due to the current in the coils."},{"_id":"62678648001682e70f000338","treeId":"655a38b74450703f0b0004a4","seq":17107225,"position":2,"parentId":"628239e4ce7078a17d000404","content":"the quantity that describes \"how much\" inductor you have is named inductance.\n\nThe larger inductor you have, the more energy you can store.... at AC. At DC, it looks just like "},{"_id":"62629c1b001682e70f000356","treeId":"655a38b74450703f0b0004a4","seq":17110687,"position":3,"parentId":"628239e4ce7078a17d000404","content":"More detail: You can think of the magnetic field in an inductor as a ball held aloft by a stream of air.\n\nActually, a feather is a better analogy; because balls fall quickly when the gust is removed, but feathers fall slowly. \n\nThe 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."},{"_id":"62f87c0e118b35815300029e","treeId":"655a38b74450703f0b0004a4","seq":17110691,"position":2,"parentId":"62823cd4ce7078a17d000402","content":"transformers"},{"_id":"6269cca7001682e70f000307","treeId":"655a38b74450703f0b0004a4","seq":17110702,"position":1,"parentId":"62f87c0e118b35815300029e","content":"[trace of current in spark gap transformer](https://commons.wikimedia.org/wiki/File:Spark-gap_transmitter_current_waveforms.png)"},{"_id":"62627ea4001682e70f000357","treeId":"655a38b74450703f0b0004a4","seq":17110726,"position":1,"parentId":"6269cca7001682e70f000307","content":"the current exhibits beats because each side is connected to a resonant circuit. So 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. "},{"_id":"62684a4e001682e70f000317","treeId":"655a38b74450703f0b0004a4","seq":17106874,"position":3.5,"parentId":"62823cd4ce7078a17d000402","content":"inductive reactance"},{"_id":"626845cf001682e70f00031a","treeId":"655a38b74450703f0b0004a4","seq":17110752,"position":0.5,"parentId":"62684a4e001682e70f000317","content":"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**."},{"_id":"62684cd0001682e70f000316","treeId":"655a38b74450703f0b0004a4","seq":17106894,"position":1,"parentId":"62684a4e001682e70f000317","content":"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**."},{"_id":"62684594001682e70f00031b","treeId":"655a38b74450703f0b0004a4","seq":17106900,"position":2,"parentId":"62684a4e001682e70f000317","content":"The quantity impedance is important because, as we will see later, it determines how much signal can get from point A to point B."},{"_id":"62683a08001682e70f00031f","treeId":"655a38b74450703f0b0004a4","seq":17106904,"position":3,"parentId":"62684a4e001682e70f000317","content":"for now, suffice to say that inductive reactance is dependent on frequency. We can show this with a scope and function generator."},{"_id":"6267f14c001682e70f000320","treeId":"655a38b74450703f0b0004a4","seq":17107002,"position":4,"parentId":"62684a4e001682e70f000317","content":"[ ] show this, using either one or two large coils: current flow depends on frequency between 10-100 kHz"},{"_id":"6267d103001682e70f000325","treeId":"655a38b74450703f0b0004a4","seq":17107030,"position":4.25,"parentId":"62684a4e001682e70f000317","content":"[ ] show that inductors are additive in series"},{"_id":"6267d701001682e70f000324","treeId":"655a38b74450703f0b0004a4","seq":17107021,"position":4.5,"parentId":"62684a4e001682e70f000317","content":"the formula for inductive reactance is [...]"},{"_id":"6267bb9c001682e70f00032b","treeId":"655a38b74450703f0b0004a4","seq":17107040,"position":4.75,"parentId":"62684a4e001682e70f000317","content":"the formula for inductance is..."},{"_id":"6267b392001682e70f00032e","treeId":"655a38b74450703f0b0004a4","seq":17107052,"position":4.90625,"parentId":"62684a4e001682e70f000317","content":"more inductance... more reactance"},{"_id":"6267bb2c001682e70f00032c","treeId":"655a38b74450703f0b0004a4","seq":17107060,"position":4.9296875,"parentId":"62684a4e001682e70f000317","content":"more inductance.... less (AC) current"},{"_id":"6267b98c001682e70f00032d","treeId":"655a38b74450703f0b0004a4","seq":17107227,"position":4.9375,"parentId":"62684a4e001682e70f000317","content":"inductance tends to block (AC) current"},{"_id":"6267f0db001682e70f000321","treeId":"655a38b74450703f0b0004a4","seq":17106999,"position":5,"parentId":"62684a4e001682e70f000317","content":"The reason that showing 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."},{"_id":"62683ea0001682e70f00031c","treeId":"655a38b74450703f0b0004a4","seq":17106976,"position":6,"parentId":"62684a4e001682e70f000317","content":"If the scope demos don't work, we can always show some [excellent illustrations of current and voltage in inductors](http://www.daviddarling.info/encyclopedia/C/current_lag_and_lead.html)"},{"_id":"6267d932001682e70f000323","treeId":"655a38b74450703f0b0004a4","seq":17107014,"position":7,"parentId":"62684a4e001682e70f000317","content":"[detailed page about inductive reactance](https://www.electronics-tutorials.ws/accircuits/ac-inductance.html)"},{"_id":"626a7340001682e70f0002ff","treeId":"655a38b74450703f0b0004a4","seq":17107039,"position":8,"parentId":"62684a4e001682e70f000317","content":"[inductive reactance video](https://www.youtube.com/watch?v=gzlZ84--JrQ)"},{"_id":"62823cb6ce7078a17d000403","treeId":"655a38b74450703f0b0004a4","seq":17107006,"position":0.44921875,"parentId":"63131420118b35815300027a","content":"capacitors, an introduction"},{"_id":"628239a1ce7078a17d000405","treeId":"655a38b74450703f0b0004a4","seq":17089108,"position":1,"parentId":"62823cb6ce7078a17d000403","content":"capacitors and fields"},{"_id":"6267b0a7001682e70f000331","treeId":"655a38b74450703f0b0004a4","seq":17107064,"position":1,"parentId":"628239a1ce7078a17d000405","content":"talking about the field in a capacitor is important when it comes to antennas, so let's talk about the field in a capacitor."},{"_id":"626a63fe001682e70f000300","treeId":"655a38b74450703f0b0004a4","seq":17106215,"position":2,"parentId":"62823cb6ce7078a17d000403","content":"capacitive reactance"},{"_id":"6267ddc7001682e70f000322","treeId":"655a38b74450703f0b0004a4","seq":17107008,"position":1,"parentId":"626a63fe001682e70f000300","content":"same as inductors offer an opposition to ac currents, capacitors offer an opposition to dc current too."},{"_id":"6267d018001682e70f000326","treeId":"655a38b74450703f0b0004a4","seq":17107031,"position":2,"parentId":"626a63fe001682e70f000300","content":"[ ] same demo as with inductors"},{"_id":"6267cfb0001682e70f000327","treeId":"655a38b74450703f0b0004a4","seq":17107032,"position":3,"parentId":"626a63fe001682e70f000300","content":"[ ] show that capacitors are additive in parallel"},{"_id":"626789e8001682e70f000336","treeId":"655a38b74450703f0b0004a4","seq":17107216,"position":3.5,"parentId":"626a63fe001682e70f000300","content":"capacitance is the quantity that determines \"how much\" capacitor you have. More capacitance can store more energy........ at DC."},{"_id":"626787a6001682e70f000337","treeId":"655a38b74450703f0b0004a4","seq":17107217,"position":3.75,"parentId":"626a63fe001682e70f000300","content":"More capacitance looks more like a wire at AC"},{"_id":"6267bd6c001682e70f000329","treeId":"655a38b74450703f0b0004a4","seq":17107036,"position":4,"parentId":"626a63fe001682e70f000300","content":"more capacitance... more (AC) current"},{"_id":"62678aa7001682e70f000334","treeId":"655a38b74450703f0b0004a4","seq":17107250,"position":0.642578125,"parentId":"63131420118b35815300027a","content":"impedance, an introduction"},{"_id":"6262d6f6001682e70f00034b","treeId":"655a38b74450703f0b0004a4","seq":17111649,"position":0.5,"parentId":"62678aa7001682e70f000334","content":"The quantity that describes the total opposition to (AC) current is called **impedance**. The root is the word **impede,** which means block."},{"_id":"6262073e001682e70f00035a","treeId":"655a38b74450703f0b0004a4","seq":17111652,"position":1,"parentId":"6262d6f6001682e70f00034b","content":"(you'll notice there are a lot of synonyms like that in EE.)"},{"_id":"6262d69b001682e70f00034c","treeId":"655a38b74450703f0b0004a4","seq":17110256,"position":0.75,"parentId":"62678aa7001682e70f000334","content":"Signals flow in inverse proportion to the impedance presented.\n\nThe reciprocal of impedance is admittance, and if it helps, you can cay that signals flow in proportion to admittance."},{"_id":"6262d66a001682e70f00034d","treeId":"655a38b74450703f0b0004a4","seq":17110259,"position":0.875,"parentId":"62678aa7001682e70f000334","content":"Like resistance, a circuit with high impedance will have little current flow.\n\nLike resistance, a circuit with low resistance will allow a lot of current to flow."},{"_id":"6262d5da001682e70f00034e","treeId":"655a38b74450703f0b0004a4","seq":17110265,"position":0.9375,"parentId":"62678aa7001682e70f000334","content":"The difference between resistance and reactance is that resistance is dissipative -- it converts energy into heat, but reactance does not; it simply sloshes it energy around for a while before giving it back."},{"_id":"6262d5b6001682e70f00034f","treeId":"655a38b74450703f0b0004a4","seq":17110275,"position":0.96875,"parentId":"62678aa7001682e70f000334","content":"Impedance **includes** the effects of resistance and reactance. As we saw, reactance varies with frequency.\n\nConsequently, impedance varies with frequency."},{"_id":"62677da1001682e70f000339","treeId":"655a38b74450703f0b0004a4","seq":17110270,"position":1,"parentId":"62678aa7001682e70f000334","content":"A circuit may presents low impedance at certain frequencies and accepts them, but reject them at other frequencies. The difference between a circuit accepting or rejecting frequencies results in current flowin a lot, a little, or not at all."},{"_id":"62676cc6001682e70f00033a","treeId":"655a38b74450703f0b0004a4","seq":17107257,"position":2,"parentId":"62678aa7001682e70f000334","content":"The thing that makes radio interesting is that a signal consists of many frequencies at once."},{"_id":"62676b5a001682e70f00033b","treeId":"655a38b74450703f0b0004a4","seq":17107260,"position":3,"parentId":"62678aa7001682e70f000334","content":"At this point we have to introduce the concept of the **frequency domain**, and it's time to tart whistling into microphones again."},{"_id":"628232fbce7078a17d000406","treeId":"655a38b74450703f0b0004a4","seq":17089126,"position":0.8359375,"parentId":"63131420118b35815300027a","content":"### **Hands-On**\n[ ] measure inductance of coil"},{"_id":"6262d17b001682e70f000352","treeId":"655a38b74450703f0b0004a4","seq":17110917,"position":0.9375,"parentId":"63131420118b35815300027a","content":"Summary: \n* There are these things called fields.\n* The fields represent the presence or absence of potential energy. \n* When the fields change, energy moves. \n* Both fields exist at once. \n* Also, when the fields change, they disturb each other.\n* There are two components that host changing fields. \n* The presence of these changing fields prevents or allows energy to flow in a circuit.\n* There can be many ripples on the surface of a pond. Likewise, there can be many frequencies present in a signal. If you are a boat, some waves bother you and some waves dont.\n* The quantity that determines whether certain waves, or frequencies, bother the non-dissipative passive components is called reactance.\n* [...]\n"},{"_id":"63131325118b35815300027b","treeId":"655a38b74450703f0b0004a4","seq":16964234,"position":1,"parentId":"63131420118b35815300027a","content":"### **Homework**"},{"_id":"62b684004656ed1a610002d1","treeId":"655a38b74450703f0b0004a4","seq":17032664,"position":0.25,"parentId":"63131325118b35815300027b","content":"**Reading:**\n\nTBD"},{"_id":"62b72565a7ef3106690007e6","treeId":"655a38b74450703f0b0004a4","seq":17032663,"position":0.5,"parentId":"63131325118b35815300027b","content":"**Videos:**"},{"_id":"62835464ce7078a17d0003ee","treeId":"655a38b74450703f0b0004a4","seq":17088907,"position":1.125,"parentId":"63131325118b35815300027b","content":"[spark gap transmitter](https://www.youtube.com/watch?v=6dx1sf2gVig)"},{"_id":"62834684ce7078a17d0003ef","treeId":"655a38b74450703f0b0004a4","seq":17088908,"position":1.4375,"parentId":"63131325118b35815300027b","content":"[another spark gap transmitter](https://www.youtube.com/watch?v=cGHLA3bQ4E8)"},{"_id":"630c09d2118b358153000283","treeId":"655a38b74450703f0b0004a4","seq":17088906,"position":1.75,"parentId":"63131325118b35815300027b","content":"https://en.wikipedia.org/wiki/Frequency_domain"},{"_id":"631830438d2f4d9bea00092a","treeId":"655a38b74450703f0b0004a4","seq":17293412,"position":3.5,"parentId":"63131325118b35815300027b","content":"a [wave machine](https://youtu.be/OI_HFnNTfyU?t=608) "},{"_id":"6318394a8d2f4d9bea00078a","treeId":"655a38b74450703f0b0004a4","seq":17032581,"position":4,"parentId":"63131325118b35815300027b","content":"[Lawrence Bragg on EM waves](https://www.youtube.com/watch?v=Vwjcn4Vl2iw)"},{"_id":"630be2ab05603773a1000285","treeId":"655a38b74450703f0b0004a4","seq":17032592,"position":5,"parentId":"63131325118b35815300027b","content":"[decent site on EM waves and propagation, with figures](http://www.physics.usyd.edu.au/teach_res/hsp/u7/t7_emr.htm)"},{"_id":"62b6cce7a7ef3106690007f6","treeId":"655a38b74450703f0b0004a4","seq":17293591,"position":5.625,"parentId":"63131325118b35815300027b","content":"videos\n\n[training video on capacitors](https://www.youtube.com/watch?v=DXPkYlOPIHs&feature=youtu.be&list=PLvplkb-chocV8788-jlgxKyTItOtyQTTE)"},{"_id":"61c40e1001c50ff7b6000b39","treeId":"655a38b74450703f0b0004a4","seq":17293420,"position":6.25,"parentId":"63131325118b35815300027b","content":"Extra credit:"},{"_id":"61c40e4801c50ff7b6000b38","treeId":"655a38b74450703f0b0004a4","seq":17293422,"position":1,"parentId":"61c40e1001c50ff7b6000b39","content":"(see also [Laithwaite on Magnets](https://www.youtube.com/watch?v=0tJfqMYHaQw))"},{"_id":"62821db6ce7078a17d000408","treeId":"655a38b74450703f0b0004a4","seq":17293432,"position":2,"parentId":"61c40e1001c50ff7b6000b39","content":"[danger high voltage](https://www.youtube.com/watch?v=TciCW8icnkQ)"},{"_id":"631312f6118b35815300027c","treeId":"655a38b74450703f0b0004a4","seq":17293438,"position":3,"parentId":"61c40e1001c50ff7b6000b39","content":"On capacitors: [exploding wire video](https://youtu.be/qyP1xZCB62E?t=2828)"},{"_id":"62673daa001682e70f00033d","treeId":"655a38b74450703f0b0004a4","seq":17293442,"position":4,"parentId":"61c40e1001c50ff7b6000b39","content":"[more on energy transfer in circuits](http://www.furryelephant.com/content/electricity/visualizing-electric-current/surface-charges-poynting-vector/)"},{"_id":"626849a4001682e70f000318","treeId":"655a38b74450703f0b0004a4","seq":17106870,"position":2,"parentId":"63131420118b35815300027a","content":"### **advanced material**"},{"_id":"62684933001682e70f000319","treeId":"655a38b74450703f0b0004a4","seq":17107282,"position":1,"parentId":"626849a4001682e70f000318","content":"[current and voltage in RL and RC circuits](http://macao.communications.museum/eng/exhibition/secondfloor/moreinfo/2_4_4_phaseshift.html)\n\n[ac inductance](https://www.electronics-tutorials.ws/accircuits/ac-inductance.html)\n\n[ac capacitance](https://www.electronics-tutorials.ws/accircuits/ac-capacitance.html)"},{"_id":"6267295f001682e70f00033f","treeId":"655a38b74450703f0b0004a4","seq":17107320,"position":2,"parentId":"626849a4001682e70f000318","content":"extra credit: we've talked about resistors, inductors, capacitors.... but have you heard about [memristors](https://en.wikipedia.org/wiki/Memristor)?"},{"_id":"61a2b19d14cd24a9700003c0","treeId":"655a38b74450703f0b0004a4","seq":17338009,"position":3,"parentId":"626849a4001682e70f000318","content":"Extra credit:"},{"_id":"61a2b0fc14cd24a9700003c1","treeId":"655a38b74450703f0b0004a4","seq":17337050,"position":1,"parentId":"61a2b19d14cd24a9700003c0","content":"[general definitions of imepdance](https://physics.stackexchange.com/questions/384/what-is-a-general-definition-of-impedance)\n\n> 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.\n\n> A general, qualitative answer in David Blackstock's book Physical Acoustics, on page 46:\n\n>>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). \n\n> 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."},{"_id":"61a2441c14cd24a9700003d7","treeId":"655a38b74450703f0b0004a4","seq":17337990,"position":1.5,"parentId":"61a2b19d14cd24a9700003c0","content":"https://en.wikipedia.org/wiki/Wave_impedance\nhttps://en.wikipedia.org/wiki/Impedance_of_free_space"},{"_id":"636860f953b88b9b46000396","treeId":"655a38b74450703f0b0004a4","seq":17259035,"position":0.86962890625,"parentId":"654fb37b305a6842700000cf","content":"## Class 5: Resonance, Feedlines (ch 7), Antennas (ch 8)"},{"_id":"62f87d19118b35815300029a","treeId":"655a38b74450703f0b0004a4","seq":16964357,"position":0.125,"parentId":"636860f953b88b9b46000396","content":"impedance"},{"_id":"62f87cc9118b35815300029c","treeId":"655a38b74450703f0b0004a4","seq":17222859,"position":0.173828125,"parentId":"636860f953b88b9b46000396","content":"resonance"},{"_id":"62008f0311f5ef04db00053e","treeId":"655a38b74450703f0b0004a4","seq":17222851,"position":1,"parentId":"62f87cc9118b35815300029c","content":"*Resonance* occurs when there is just as much *capacitive* reactance as there is *inductive* reactance."},{"_id":"620048e311f5ef04db000546","treeId":"655a38b74450703f0b0004a4","seq":17223091,"position":1.5,"parentId":"62f87cc9118b35815300029c","content":"series resonant circuits pass the resonant frequency and block everything else."},{"_id":"620047fc11f5ef04db000547","treeId":"655a38b74450703f0b0004a4","seq":17223110,"position":1.75,"parentId":"62f87cc9118b35815300029c","content":"parallel resonant circuits block the resonant frequency"},{"_id":"6200886111f5ef04db000541","treeId":"655a38b74450703f0b0004a4","seq":17222857,"position":2,"parentId":"62f87cc9118b35815300029c","content":"see page 4-20"},{"_id":"61ffeec611f5ef04db000556","treeId":"655a38b74450703f0b0004a4","seq":17338493,"position":3,"parentId":"62f87cc9118b35815300029c","content":"video: [a better description of resonance](https://www.youtube.com/watch?v=dihQuwrf9yQ)"},{"_id":"6200893511f5ef04db00053f","treeId":"655a38b74450703f0b0004a4","seq":17222854,"position":0.22265625,"parentId":"636860f953b88b9b46000396","content":"q-factor"},{"_id":"62007f1811f5ef04db000543","treeId":"655a38b74450703f0b0004a4","seq":17223114,"position":0.25,"parentId":"6200893511f5ef04db00053f","content":"The concept of resonance is a bit fuzzy."},{"_id":"6200454911f5ef04db000548","treeId":"655a38b74450703f0b0004a4","seq":17223393,"position":0.375,"parentId":"6200893511f5ef04db00053f","content":"in the viciinty of the resonant frequency, the capcitive and uinductive reactance aren't exactly the same -- but they're close.\n\nConsequently, there is some filtering effect -- just not as much as at the resonance point. So, the phenomena of resonance has some \"width\" associated with it."},{"_id":"620085e511f5ef04db000542","treeId":"655a38b74450703f0b0004a4","seq":17223389,"position":0.5,"parentId":"6200893511f5ef04db00053f","content":"The term q-factor refers to the width of the resonance."},{"_id":"620088ba11f5ef04db000540","treeId":"655a38b74450703f0b0004a4","seq":17222855,"position":1,"parentId":"6200893511f5ef04db00053f","content":"see page 4-22 in the textbook"},{"_id":"62007df311f5ef04db000544","treeId":"655a38b74450703f0b0004a4","seq":17222874,"position":0.2236328125,"parentId":"636860f953b88b9b46000396","content":"filters"},{"_id":"62007de011f5ef04db000545","treeId":"655a38b74450703f0b0004a4","seq":17226099,"position":1,"parentId":"62007df311f5ef04db000544","content":"Basic resonant circuits can be combined to create filters."},{"_id":"6200198e11f5ef04db00054d","treeId":"655a38b74450703f0b0004a4","seq":17224057,"position":0.22900390625,"parentId":"636860f953b88b9b46000396","content":"feedlines"},{"_id":"620011dd11f5ef04db000550","treeId":"655a38b74450703f0b0004a4","seq":17224394,"position":0.125,"parentId":"6200198e11f5ef04db00054d","content":"A transmission line is a circuit that is specially designed to carry radio-frequency alternating currents.\n(Feedlines are also called transmission lines.)"},{"_id":"62000f2911f5ef04db000551","treeId":"655a38b74450703f0b0004a4","seq":17224355,"position":1,"parentId":"620011dd11f5ef04db000550","content":"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."},{"_id":"620015d711f5ef04db00054f","treeId":"655a38b74450703f0b0004a4","seq":17224431,"position":0.375,"parentId":"6200198e11f5ef04db00054d","content":"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."},{"_id":"628320d5ce7078a17d0003f0","treeId":"655a38b74450703f0b0004a4","seq":17224474,"position":0.5,"parentId":"6200198e11f5ef04db00054d","content":"This [animation of a transmission line](https://en.wikipedia.org/wiki/File:Transmission_line_animation3.gif) 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."},{"_id":"62001aa711f5ef04db00054c","treeId":"655a38b74450703f0b0004a4","seq":17224507,"position":1,"parentId":"6200198e11f5ef04db00054d","content":"This excellent [bell labs wave machine video](https://www.youtube.com/watch?v=DovunOxlY1k) clearly explains the wave phenomena in transmission lines."},{"_id":"62f87c94118b35815300029d","treeId":"655a38b74450703f0b0004a4","seq":16964360,"position":0.234375,"parentId":"636860f953b88b9b46000396","content":"standing waves"},{"_id":"61fff6f611f5ef04db000553","treeId":"655a38b74450703f0b0004a4","seq":17224794,"position":0.5,"parentId":"62f87c94118b35815300029d","content":"First, the consequences of impedance mismatch:"},{"_id":"61fff47511f5ef04db000555","treeId":"655a38b74450703f0b0004a4","seq":17224828,"position":0.75,"parentId":"62f87c94118b35815300029d","content":"[wave machine](https://en.wikipedia.org/wiki/John_N._Shive#Shive_wave_machine) demos:"},{"_id":"6200232611f5ef04db000549","treeId":"655a38b74450703f0b0004a4","seq":17223596,"position":1,"parentId":"62f87c94118b35815300029d","content":"[matched impedance video](https://www.youtube.com/watch?v=FaCyg0dB_aY)"},{"_id":"6200226d11f5ef04db00054a","treeId":"655a38b74450703f0b0004a4","seq":17223595,"position":2,"parentId":"62f87c94118b35815300029d","content":"[mismatched impedance video](https://www.youtube.com/watch?v=AjzBGC4tGTo)"},{"_id":"61fff66511f5ef04db000554","treeId":"655a38b74450703f0b0004a4","seq":17224795,"position":3,"parentId":"62f87c94118b35815300029d","content":"Then"},{"_id":"61ff937e11f5ef04db00055d","treeId":"655a38b74450703f0b0004a4","seq":17226185,"position":4,"parentId":"62f87c94118b35815300029d","content":"page 7-15 in the book"},{"_id":"61ffe82211f5ef04db000557","treeId":"655a38b74450703f0b0004a4","seq":17224999,"position":0.6162109375,"parentId":"636860f953b88b9b46000396","content":"length of antennas, velocity factor"},{"_id":"61ffe76111f5ef04db000558","treeId":"655a38b74450703f0b0004a4","seq":17225064,"position":1,"parentId":"61ffe82211f5ef04db000557","content":"The fundamental relationship is:\n\nv = f . l\n\nMore or less v = c, (where c is the speed of light)\n\nHowever v = vf . c, where vf is the velocoty factor: Some fraction or percentage of the speed of light."},{"_id":"61ff6fe711f5ef04db00055e","treeId":"655a38b74450703f0b0004a4","seq":17226692,"position":2,"parentId":"61ffe82211f5ef04db000557","content":"For the purposes of this course, the number to remember for the speed of light is 300 million meters per second"},{"_id":"626b4fcbc8c25e26130002f3","treeId":"655a38b74450703f0b0004a4","seq":17104668,"position":0.998046875,"parentId":"636860f953b88b9b46000396","content":"antennas"},{"_id":"61ffe22d11f5ef04db000559","treeId":"655a38b74450703f0b0004a4","seq":17225239,"position":0.5,"parentId":"626b4fcbc8c25e26130002f3","content":"Antennas are tuned circuits: They include resistance and reactance; where there are equal amounts of capacitive and inductive reactance.\n"},{"_id":"626b4fa2c8c25e26130002f4","treeId":"655a38b74450703f0b0004a4","seq":17225180,"position":1,"parentId":"626b4fcbc8c25e26130002f3","content":"To see where the capacitance comes from, look at this [animation showing the transformation from a capacitor to antenna](https://i.gifer.com/F8Qb.gif)."},{"_id":"62671fb3001682e70f000341","treeId":"655a38b74450703f0b0004a4","seq":17107325,"position":1.875,"parentId":"626b4fcbc8c25e26130002f3","content":"[more on dipoles](http://cst2cd.acceptance.brimit.com/academia/examples/wire-dipole-antenna)"},{"_id":"626b46b4c8c25e26130002f6","treeId":"655a38b74450703f0b0004a4","seq":17104688,"position":2,"parentId":"626b4fcbc8c25e26130002f3","content":"[monpole and dipole radiation patterns](https://www.acs.psu.edu/drussell/demos/rad2/mdq.html)"},{"_id":"6268c81a001682e70f00030c","treeId":"655a38b74450703f0b0004a4","seq":17106792,"position":3,"parentId":"626b4fcbc8c25e26130002f3","content":"[dipole and reflector animation](http://www.das-eng.com/projects/dipole-antenna-and-reflector/)"},{"_id":"6268c515001682e70f00030d","treeId":"655a38b74450703f0b0004a4","seq":17106796,"position":4,"parentId":"626b4fcbc8c25e26130002f3","content":"[horn antenna animations](http://antsim.elmag.org/horn/)"},{"_id":"6268bfc1001682e70f00030e","treeId":"655a38b74450703f0b0004a4","seq":17106798,"position":5,"parentId":"626b4fcbc8c25e26130002f3","content":"[yagi antenna animation](http://antsim.elmag.org/yagi/)"},{"_id":"61a271f114cd24a9700003d4","treeId":"655a38b74450703f0b0004a4","seq":17337859,"position":5.5,"parentId":"626b4fcbc8c25e26130002f3","content":"[yagi antenna block diagram](http://homepage.usask.ca/~bdb368/ham/basic/block_diagrams/yagi_uda_explanation.html) (exam)"},{"_id":"61a1865df63d9cd07d000b50","treeId":"655a38b74450703f0b0004a4","seq":17338635,"position":5.75,"parentId":"626b4fcbc8c25e26130002f3","content":"https://m.youtube.com/watch?v=JYKEZATy4Fk"},{"_id":"626b2973c8c25e26130002f8","treeId":"655a38b74450703f0b0004a4","seq":17335829,"position":6,"parentId":"626b4fcbc8c25e26130002f3","content":"extra credit:\n[antenna basics, part 1](https://www.allaboutcircuits.com/technical-articles/an-introduction-to-antenna-basics/)\n[antenna basics part 2](https://www.allaboutcircuits.com/technical-articles/antenna-basics-field-radiation-patterns-permittivity-directivity-gain/)"},{"_id":"62671e2e001682e70f000342","treeId":"655a38b74450703f0b0004a4","seq":17334183,"position":1,"parentId":"626b2973c8c25e26130002f8","content":"This [playlist of animations shows the electric field](https://www.youtube.com/playlist?list=PL1Uym63wTrJq7zDwY22F8Xa1Uqf16rXyS) in the vicinity of various antennas.\n\n"},{"_id":"6326564dc82956ebf200022e","treeId":"655a38b74450703f0b0004a4","seq":16964478,"position":5,"parentId":"636860f953b88b9b46000396","content":"### **Homework**"},{"_id":"6200a64f11f5ef04db00053d","treeId":"655a38b74450703f0b0004a4","seq":17293445,"position":2,"parentId":"6326564dc82956ebf200022e","content":"read the chapter on propagation"},{"_id":"61ffd0fe11f5ef04db00055a","treeId":"655a38b74450703f0b0004a4","seq":17225381,"position":2.5,"parentId":"6326564dc82956ebf200022e","content":"read chapter 7, on transmission lines"},{"_id":"61ffd0bd11f5ef04db00055b","treeId":"655a38b74450703f0b0004a4","seq":17225380,"position":2.75,"parentId":"6326564dc82956ebf200022e","content":"read chapter 8, on antennas"},{"_id":"64424f099a63635172000700","treeId":"655a38b74450703f0b0004a4","seq":17293511,"position":2.875,"parentId":"6326564dc82956ebf200022e","content":"[video on Decibels](https://greatscottgadgets.com/sdr/3/)"},{"_id":"6374ed145d0fbe476c0003e2","treeId":"655a38b74450703f0b0004a4","seq":17293451,"position":3,"parentId":"6326564dc82956ebf200022e","content":"Extra credit:\n[video about microwaving grapes](https://www.youtube.com/watch?v=wCrtk-pyP0I), in which grapes are the perfect size and shape to act as antennas in a microwave oven, and do interesting things as a result."},{"_id":"6368606c53b88b9b46000397","treeId":"655a38b74450703f0b0004a4","seq":17335048,"position":0.871826171875,"parentId":"654fb37b305a6842700000cf","content":"## Class 5.5 (Self-Study) Propagation\n"},{"_id":"644265069a636351720006fb","treeId":"655a38b74450703f0b0004a4","seq":17335082,"position":0.25,"parentId":"6368606c53b88b9b46000397","content":"radio waves in free space, propagation, antennas"},{"_id":"633267334ac6fd1762000753","treeId":"655a38b74450703f0b0004a4","seq":16887526,"position":0.5,"parentId":"644265069a636351720006fb","content":"* Directivity (decibels, again)"},{"_id":"61a3523e14cd24a9700003b3","treeId":"655a38b74450703f0b0004a4","seq":17334514,"position":0.75,"parentId":"644265069a636351720006fb","content":"video: [RCAF training film on electromagnetic wave propagation](https://www.youtube.com/watch?v=7bDyA5t1ldU)"},{"_id":"61a3123214cd24a9700003b8","treeId":"655a38b74450703f0b0004a4","seq":17335104,"position":1.125,"parentId":"6368606c53b88b9b46000397","content":"antennas"},{"_id":"63cb824478d65a6bc300019d","treeId":"655a38b74450703f0b0004a4","seq":17335774,"position":2,"parentId":"61a3123214cd24a9700003b8","content":"video: [RCAF training video on directivity](https://www.youtube.com/watch?v=md7GjQQ2YA0) (very good)"},{"_id":"61a34a5714cd24a9700003b5","treeId":"655a38b74450703f0b0004a4","seq":17335780,"position":2.5,"parentId":"61a3123214cd24a9700003b8","content":"video: [RCAF training video on antenna bandwidth](https://www.youtube.com/watch?v=9iV_YICgifA) (very good)"},{"_id":"630bd96b118b35815300028a","treeId":"655a38b74450703f0b0004a4","seq":17335121,"position":3,"parentId":"61a3123214cd24a9700003b8","content":"Directive antennas work on the principle of interference, where waves add destructively or constructively. Here is an [animation ofinterference](http://www.physics.usyd.edu.au/teach_res/hsp/u7/t7_emr_files/image024.gif)."},{"_id":"61a3127114cd24a9700003b7","treeId":"655a38b74450703f0b0004a4","seq":17335085,"position":2,"parentId":"6368606c53b88b9b46000397","content":"propagation"},{"_id":"63cb39b578d65a6bc30001a0","treeId":"655a38b74450703f0b0004a4","seq":17335794,"position":0.25,"parentId":"61a3127114cd24a9700003b7","content":"Here is a **very good** [army training video on ground wave and sky wave propagation](https://www.youtube.com/watch?v=YVxprkGqCPk). This basically teaches everything you need to know."},{"_id":"630bda04118b358153000289","treeId":"655a38b74450703f0b0004a4","seq":17335181,"position":0.5,"parentId":"61a3127114cd24a9700003b7","content":"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](http://www.physics.usyd.edu.au/teach_res/hsp/u7/t7_emr_files/image014.gif) 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."},{"_id":"63cb4f7278d65a6bc300019f","treeId":"655a38b74450703f0b0004a4","seq":17335282,"position":2,"parentId":"61a3127114cd24a9700003b7","content":"Extra credit: This video on so-called [tropo scatter](https://youtu.be/RjiSWaUQE-0?t=120) is mostly a waste of time."},{"_id":"62f86df4118b3581530002a0","treeId":"655a38b74450703f0b0004a4","seq":17259045,"position":0.8740234375,"parentId":"654fb37b305a6842700000cf","content":"## Class 6: Receivers (ch 14), modulation (ch 13), block diagrams (ch 13)"},{"_id":"62670eaf001682e70f000344","treeId":"655a38b74450703f0b0004a4","seq":17337084,"position":0.3125,"parentId":"62f86df4118b3581530002a0","content":"### **Introduction**"},{"_id":"62670e8e001682e70f000345","treeId":"655a38b74450703f0b0004a4","seq":17293302,"position":1,"parentId":"62670eaf001682e70f000344","content":"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."},{"_id":"61a2ab2714cd24a9700003c3","treeId":"655a38b74450703f0b0004a4","seq":17337111,"position":2,"parentId":"62670eaf001682e70f000344","content":"In the next class, we learned about sending these waves over a cable, and then out through an antenna."},{"_id":"61a2a9bc14cd24a9700003c4","treeId":"655a38b74450703f0b0004a4","seq":17337123,"position":3,"parentId":"62670eaf001682e70f000344","content":"In this class, we will look at capturing waves, taking them apart, and turning them into intelligence."},{"_id":"61c414db01c50ff7b6000b34","treeId":"655a38b74450703f0b0004a4","seq":17337761,"position":0.359375,"parentId":"62f86df4118b3581530002a0","content":"###**Receivers**\n\n[Fundamental components and block diagram](https://www.researchgate.net/figure/The-circuit-of-a-simple-radio-receiver-9_fig1_317185184)"},{"_id":"61a2937014cd24a9700003c7","treeId":"655a38b74450703f0b0004a4","seq":17337512,"position":0.625,"parentId":"61c414db01c50ff7b6000b34","content":"This is a block diagram: It's like a circuit, but...."},{"_id":"61c4148701c50ff7b6000b35","treeId":"655a38b74450703f0b0004a4","seq":17293346,"position":1,"parentId":"61c414db01c50ff7b6000b34","content":"Antenna (dealt with this already)"},{"_id":"61c4140a01c50ff7b6000b36","treeId":"655a38b74450703f0b0004a4","seq":17337461,"position":2,"parentId":"61c414db01c50ff7b6000b34","content":"Tuned circuit, also called a selector\n(dealt with this already)"},{"_id":"61c412ff01c50ff7b6000b37","treeId":"655a38b74450703f0b0004a4","seq":17293351,"position":3,"parentId":"61c414db01c50ff7b6000b34","content":"Detector"},{"_id":"61a8adc992741f38d300039e","treeId":"655a38b74450703f0b0004a4","seq":17331159,"position":4,"parentId":"61c414db01c50ff7b6000b34","content":"This is the first of several block diagrams relevant to the exam."},{"_id":"626795b1001682e70f000333","treeId":"655a38b74450703f0b0004a4","seq":17338365,"position":0.36328125,"parentId":"62f86df4118b3581530002a0","content":"### **Hands-On**"},{"_id":"62b73fdba7ef3106690007e0","treeId":"655a38b74450703f0b0004a4","seq":17107126,"position":1,"parentId":"626795b1001682e70f000333","content":"[ ] assemble our coil, measure inductance,"},{"_id":"63130d21118b35815300027e","treeId":"655a38b74450703f0b0004a4","seq":17294197,"position":1,"parentId":"62b73fdba7ef3106690007e0","content":"[ ] show filtering"},{"_id":"61c3bbea01c50ff7b6000b41","treeId":"655a38b74450703f0b0004a4","seq":17294179,"position":1.5,"parentId":"626795b1001682e70f000333","content":"[ ] attach antenna"},{"_id":"61c3bb9201c50ff7b6000b42","treeId":"655a38b74450703f0b0004a4","seq":17294183,"position":1.75,"parentId":"626795b1001682e70f000333","content":"[ ] connect detector"},{"_id":"61c3bb2a01c50ff7b6000b43","treeId":"655a38b74450703f0b0004a4","seq":17294190,"position":1.875,"parentId":"626795b1001682e70f000333","content":"[ ] connect headphones"},{"_id":"62f86c6a118b3581530002a2","treeId":"655a38b74450703f0b0004a4","seq":17337715,"position":0.3671875,"parentId":"62f86df4118b3581530002a0","content":"diodes, converting AC to DC"},{"_id":"61a281c514cd24a9700003cd","treeId":"655a38b74450703f0b0004a4","seq":17337813,"position":0.5,"parentId":"62f86c6a118b3581530002a2","content":"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."},{"_id":"63cbc61578d65a6bc300019b","treeId":"655a38b74450703f0b0004a4","seq":17331144,"position":1,"parentId":"62f86c6a118b3581530002a2","content":"Video: [cat's whisker detector](https://youtu.be/2roG4jIjvEk?t=983)"},{"_id":"61a8be4f92741f38d300039b","treeId":"655a38b74450703f0b0004a4","seq":17335853,"position":2,"parentId":"62f86c6a118b3581530002a2","content":"Once again: There are conductors, semiconductors, dielectrics, insulators."},{"_id":"61a8bdb992741f38d300039c","treeId":"655a38b74450703f0b0004a4","seq":17335862,"position":3,"parentId":"62f86c6a118b3581530002a2","content":"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."},{"_id":"61a8bad792741f38d300039d","treeId":"655a38b74450703f0b0004a4","seq":17417293,"position":4,"parentId":"62f86c6a118b3581530002a2","content":"[ ] Please take a look at these diodes using my hand lens."},{"_id":"630c0c51118b358153000281","treeId":"655a38b74450703f0b0004a4","seq":17417307,"position":0.369140625,"parentId":"62f86df4118b3581530002a0","content":"### **The frequency domain**"},{"_id":"61c419c801c50ff7b6000b30","treeId":"655a38b74450703f0b0004a4","seq":17334139,"position":0.1875,"parentId":"630c0c51118b358153000281","content":"First, review what we are familiar with: Graphs of amplitude vs time"},{"_id":"61a3cf4e14cd24a9700003ad","treeId":"655a38b74450703f0b0004a4","seq":17334188,"position":1,"parentId":"61c419c801c50ff7b6000b30","content":"We all remember what a sinusoidal waveform looks like."},{"_id":"61a3ceb214cd24a9700003ae","treeId":"655a38b74450703f0b0004a4","seq":17334189,"position":2,"parentId":"61c419c801c50ff7b6000b30","content":"We can also create other shapes of waveforms."},{"_id":"62670696001682e70f000347","treeId":"655a38b74450703f0b0004a4","seq":17334617,"position":0.19921875,"parentId":"630c0c51118b358153000281","content":"The Fourier transform, intuitively:\n* Signals consist of many frequencies, all at once.\n* Even when a signal consists of mostly one frequency, the others are merely small, not zero."},{"_id":"62b75161a7ef3106690007dd","treeId":"655a38b74450703f0b0004a4","seq":17293752,"position":0.2109375,"parentId":"630c0c51118b358153000281","content":"We demonstrate this with audio spectrograms: Whistling into microphones, running Baudline"},{"_id":"62824b27ce7078a17d0003fa","treeId":"655a38b74450703f0b0004a4","seq":17089082,"position":1,"parentId":"62b75161a7ef3106690007dd","content":"[ ] microphone, baudline application"},{"_id":"61c4172001c50ff7b6000b33","treeId":"655a38b74450703f0b0004a4","seq":17293337,"position":1.5,"parentId":"62b75161a7ef3106690007dd","content":"[ ] one person whistling"},{"_id":"628248d3ce7078a17d0003fc","treeId":"655a38b74450703f0b0004a4","seq":17089081,"position":2,"parentId":"62b75161a7ef3106690007dd","content":"[ ] two people whistling at once"},{"_id":"62824857ce7078a17d0003fd","treeId":"655a38b74450703f0b0004a4","seq":17293338,"position":3,"parentId":"62b75161a7ef3106690007dd","content":"takeaway: a time-domain waveform (may) consist of multiple frequency-domain signals"},{"_id":"61c4194e01c50ff7b6000b31","treeId":"655a38b74450703f0b0004a4","seq":17337247,"position":0.28125,"parentId":"630c0c51118b358153000281","content":"Next we talk about graphs of amplitude vs frequency. This site shows the [frequency spectrum of different types of signals](http://www.azimadli.com/vibman/examplesofsomewaveformsandtheirspectra.htm) (including an impulse, as in the spark-gap transmitter)."},{"_id":"61a3494514cd24a9700003b6","treeId":"655a38b74450703f0b0004a4","seq":17337268,"position":0.5,"parentId":"61c4194e01c50ff7b6000b31","content":"video: [RCAF training video that deals, in part, with the Fourier transform](https://youtu.be/9iV_YICgifA?t=37)"},{"_id":"61a3ddb114cd24a9700003ab","treeId":"655a38b74450703f0b0004a4","seq":17334585,"position":1,"parentId":"61c4194e01c50ff7b6000b31","content":"video: [building a square wave out a sine wave](https://www.youtube.com/watch?v=k8FXF1KjzY0)"},{"_id":"61a3d02414cd24a9700003ac","treeId":"655a38b74450703f0b0004a4","seq":17334591,"position":2,"parentId":"61c4194e01c50ff7b6000b31","content":"video: [building a triangle wave out of sine waves](https://www.youtube.com/watch?v=wNwJOBmqBsc)"},{"_id":"61a3c0a214cd24a9700003af","treeId":"655a38b74450703f0b0004a4","seq":17334596,"position":3,"parentId":"61c4194e01c50ff7b6000b31","content":"animation: [Fourier transform animation](https://commons.wikimedia.org/wiki/File:Fourier_transform_time_and_frequency_domains.gif)"},{"_id":"61a3afbb14cd24a9700003b0","treeId":"655a38b74450703f0b0004a4","seq":17334611,"position":5,"parentId":"61c4194e01c50ff7b6000b31","content":"a not very intuitive [sound synthesis toy](http://demonstrations.wolfram.com/FourierSoundSynthesis/)"},{"_id":"61a29f3b14cd24a9700003c5","treeId":"655a38b74450703f0b0004a4","seq":17337343,"position":6,"parentId":"61c4194e01c50ff7b6000b31","content":"The thing to remember is that any signal can be broken up into sine waves, and sine-waves self-propagate."},{"_id":"61c3f0b201c50ff7b6000b3b","treeId":"655a38b74450703f0b0004a4","seq":17335841,"position":1.62499875,"parentId":"630c0c51118b358153000281","content":"Deferred:\nWe choose not to do the following, for reasons of time (also the spectrum analyzer is broken)"},{"_id":"62b75570a7ef3106690007db","treeId":"655a38b74450703f0b0004a4","seq":17293823,"position":1.00001,"parentId":"61c3f0b201c50ff7b6000b3b","content":"spectrum analyzer and non-sinusoidal waves"},{"_id":"628246eace7078a17d0003fe","treeId":"655a38b74450703f0b0004a4","seq":17089080,"position":3,"parentId":"62b75570a7ef3106690007db","content":"[ ] Function generator, scope, square wave generator, etc"},{"_id":"626735e3001682e70f00033e","treeId":"655a38b74450703f0b0004a4","seq":17107296,"position":4,"parentId":"62b75570a7ef3106690007db","content":"[spectrum of real-world square waves](http://www.ganssle.com/rants/fourier_and_us.html)"},{"_id":"62670801001682e70f000346","treeId":"655a38b74450703f0b0004a4","seq":17335842,"position":1.687499375,"parentId":"630c0c51118b358153000281","content":"(Advanced qualification) Signals can have a dc component as well as an AC component."},{"_id":"61a27b9b14cd24a9700003ce","treeId":"655a38b74450703f0b0004a4","seq":17337878,"position":0.37109375,"parentId":"62f86df4118b3581530002a0","content":"What if there is no audio signal? What if there's just a carrier?"},{"_id":"61a2763514cd24a9700003cf","treeId":"655a38b74450703f0b0004a4","seq":17338367,"position":1,"parentId":"61a27b9b14cd24a9700003ce","content":"beats"},{"_id":"61a227d314cd24a9700003db","treeId":"655a38b74450703f0b0004a4","seq":17338357,"position":1.25,"parentId":"61a27b9b14cd24a9700003ce","content":"image of [beat phenomenon](http://www.met.reading.ac.uk/pplato2/h-flap/phys5_7f_22.png), showing superposition or interference of waves"},{"_id":"61a2160a14cd24a9700003df","treeId":"655a38b74450703f0b0004a4","seq":17338354,"position":1,"parentId":"61a227d314cd24a9700003db","content":"[from this page](http://www.met.reading.ac.uk/pplato2/h-flap/phys5_7.html)"},{"_id":"61a2303814cd24a9700003da","treeId":"655a38b74450703f0b0004a4","seq":17338341,"position":1.5,"parentId":"61a27b9b14cd24a9700003ce","content":"video of [beats using tuning forks](https://www.youtube.com/watch?v=V8W4Djz6jnY)"},{"_id":"61a20dd414cd24a9700003e1","treeId":"655a38b74450703f0b0004a4","seq":17338369,"position":1,"parentId":"61a2303814cd24a9700003da","content":"[video explanation](https://www.youtube.com/watch?v=4M72kQulGKk)"},{"_id":"61a221f314cd24a9700003dc","treeId":"655a38b74450703f0b0004a4","seq":17417464,"position":2.25,"parentId":"61a27b9b14cd24a9700003ce","content":"[a simple tone generator](https://www.szynalski.com/tone-generator/)\n\nand\n\n\n[a more elaborate tone generator](http://onlinetonegenerator.com/)"},{"_id":"61a275c414cd24a9700003d1","treeId":"655a38b74450703f0b0004a4","seq":17337845,"position":3,"parentId":"61a27b9b14cd24a9700003ce","content":"mixing an audio signal with a carrier"},{"_id":"61a275df14cd24a9700003d0","treeId":"655a38b74450703f0b0004a4","seq":17338338,"position":4,"parentId":"61a27b9b14cd24a9700003ce","content":"there is a similar phenomenon that occurs with radio signals, called mixing"},{"_id":"61a1d52414cd24a9700003e3","treeId":"655a38b74450703f0b0004a4","seq":17338412,"position":0.5,"parentId":"61a275df14cd24a9700003d0","content":"Advanced: [mixers](https://en.wikipedia.org/wiki/Frequency_mixer)"},{"_id":"61a2076d14cd24a9700003e2","treeId":"655a38b74450703f0b0004a4","seq":17338372,"position":1,"parentId":"61a275df14cd24a9700003d0","content":"Advanced: \"mixing\" is due to non-linearity in the response of RF components, but [it also happens in ears, too](https://blog.soton.ac.uk/soundwaves/hearing-sounds/5-sum-and-difference-tones/)."},{"_id":"61a1c4e614cd24a9700003e6","treeId":"655a38b74450703f0b0004a4","seq":17338482,"position":2,"parentId":"61a275df14cd24a9700003d0","content":"[more detail](https://en.wikipedia.org/wiki/Combination_tone)"},{"_id":"61a1c3dd14cd24a9700003e7","treeId":"655a38b74450703f0b0004a4","seq":17338492,"position":3,"parentId":"61a275df14cd24a9700003d0","content":"[and more](http://hyperphysics.phy-astr.gsu.edu/hbase/Audio/sumdif.html)"},{"_id":"61a2136214cd24a9700003e0","treeId":"655a38b74450703f0b0004a4","seq":17338378,"position":5,"parentId":"61a27b9b14cd24a9700003ce","content":"beat frequency oscillator demo"},{"_id":"62b735b1a7ef3106690007e1","treeId":"655a38b74450703f0b0004a4","seq":17337817,"position":1.13671875,"parentId":"62f86df4118b3581530002a0","content":"### **modulation (introduction)**"},{"_id":"62b73508a7ef3106690007e4","treeId":"655a38b74450703f0b0004a4","seq":17331151,"position":0.25,"parentId":"62b735b1a7ef3106690007e1","content":"Depiction of OOK, in the frequency domain and time domain"},{"_id":"62838e51ce7078a17d0003ec","treeId":"655a38b74450703f0b0004a4","seq":17089075,"position":1,"parentId":"62b73508a7ef3106690007e4","content":"[ ] show CW on a web SDR"},{"_id":"628225b5ce7078a17d000407","treeId":"655a38b74450703f0b0004a4","seq":17294061,"position":2,"parentId":"62b73508a7ef3106690007e4","content":"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\")"},{"_id":"61a299e514cd24a9700003c6","treeId":"655a38b74450703f0b0004a4","seq":17337407,"position":1.1484375,"parentId":"62f86df4118b3581530002a0","content":"Modulation (continued)"},{"_id":"62b73520a7ef3106690007e3","treeId":"655a38b74450703f0b0004a4","seq":17337408,"position":1,"parentId":"61a299e514cd24a9700003c6","content":"Depiction of AM, in the frequency domain"},{"_id":"63cbd72e78d65a6bc300019a","treeId":"655a38b74450703f0b0004a4","seq":17294037,"position":2,"parentId":"62b73520a7ef3106690007e3","content":"video: [AM modulation demonstrated with an oscilloscope](https://youtu.be/2roG4jIjvEk?t=699)"},{"_id":"628241ecce7078a17d000401","treeId":"655a38b74450703f0b0004a4","seq":17294036,"position":3,"parentId":"62b73520a7ef3106690007e3","content":"[ ] AM whistling into microphone, show on audio spectrogram"},{"_id":"61a2ef4f14cd24a9700003be","treeId":"655a38b74450703f0b0004a4","seq":17336082,"position":4,"parentId":"62b73520a7ef3106690007e3","content":"[AM modulation at the signal identification wiki](https://www.sigidwiki.com/wiki/Amplitude_Modulation_(AM))"},{"_id":"62b73552a7ef3106690007e2","treeId":"655a38b74450703f0b0004a4","seq":17337409,"position":2,"parentId":"61a299e514cd24a9700003c6","content":"Depiction of FM, in the frequency domain"},{"_id":"62824259ce7078a17d000400","treeId":"655a38b74450703f0b0004a4","seq":17331147,"position":0.5,"parentId":"62b73552a7ef3106690007e2","content":"[ ] FM whistling on audio spectogram (high, low, high, low tone)"},{"_id":"62838de8ce7078a17d0003ed","treeId":"655a38b74450703f0b0004a4","seq":17331148,"position":1,"parentId":"62b73552a7ef3106690007e2","content":"[ ] show FM with sub-audible tone on an SDR"},{"_id":"61a386f414cd24a9700003b2","treeId":"655a38b74450703f0b0004a4","seq":17334629,"position":2,"parentId":"62b73552a7ef3106690007e2","content":"FM signal on [signal ID wiki](https://www.sigidwiki.com/wiki/NFM_Voice)"},{"_id":"61a849d292741f38d30003a4","treeId":"655a38b74450703f0b0004a4","seq":17334374,"position":1.265625,"parentId":"62f86df4118b3581530002a0","content":"Sensitivity and selectivity"},{"_id":"61a7f96292741f38d30003a7","treeId":"655a38b74450703f0b0004a4","seq":18957580,"position":0.99999,"parentId":"61a849d292741f38d30003a4","content":"**Sensitivity** is a function of the detector. In the context of our crystal radios, some detectors are good. Other detectors are better."},{"_id":"61a2f80614cd24a9700003bc","treeId":"655a38b74450703f0b0004a4","seq":17335932,"position":1,"parentId":"61a7f96292741f38d30003a7","content":"The sensitivity of these point-contact diode detectors is pretty decent."},{"_id":"61a2f71114cd24a9700003bd","treeId":"655a38b74450703f0b0004a4","seq":17335943,"position":2,"parentId":"61a7f96292741f38d30003a7","content":"The sensitivity of these PN junction diodes is not as good."},{"_id":"5ca2b1c8707a84036a1caa1a","treeId":"655a38b74450703f0b0004a4","seq":18957581,"position":1,"parentId":"61a849d292741f38d30003a4","content":"**Selectivity** is a function of the tuned circuit (selector) and, in other types of receivers, the rest of the RF signal chain."},{"_id":"61a2fa6614cd24a9700003ba","treeId":"655a38b74450703f0b0004a4","seq":17335897,"position":1,"parentId":"5ca2b1c8707a84036a1caa1a","content":"In class 5, we learned about the so-called Q-factor. The Q of these tuned circuits in our crystal receiver is low. "},{"_id":"61a853f492741f38d30003a1","treeId":"655a38b74450703f0b0004a4","seq":17334376,"position":3.78125,"parentId":"62f86df4118b3581530002a0","content":"Other types of receivers"},{"_id":"61a8530a92741f38d30003a2","treeId":"655a38b74450703f0b0004a4","seq":17417466,"position":1,"parentId":"61a853f492741f38d30003a1","content":"[block diagram study page](http://homepage.usask.ca/~bdb368/ham/basic/block_diagrams/index.html)\n* [SSB/CW receiver](http://homepage.usask.ca/~bdb368/ham/basic/block_diagrams/single_sideband_cw_receiver_explanation.html) pg 14-11\n\n\n\n* [FM receiver](http://homepage.usask.ca/~bdb368/ham/basic/block_diagrams/frequency_modulation_receiver_explanation.html) pg 14-10"},{"_id":"61a8ace192741f38d300039f","treeId":"655a38b74450703f0b0004a4","seq":17334377,"position":4.171875,"parentId":"62f86df4118b3581530002a0","content":"Other types of modulation"},{"_id":"61a8acab92741f38d30003a0","treeId":"655a38b74450703f0b0004a4","seq":17417523,"position":1,"parentId":"61a8ace192741f38d300039f","content":"PSK - phase shift keying\n\nFSK - frequency shift keying\n\ncompare and contrast with\nOOK"},{"_id":"61eb5877e0ec83272c000483","treeId":"655a38b74450703f0b0004a4","seq":17331230,"position":4.75,"parentId":"62f86df4118b3581530002a0","content":"**Administrivia:**\n[ ] schedule weekend session\n[ ] talk about exam scheduling practicalities\n[ ] remind about stuff to memorize\n[ ] point out exam resources added (bank with explanations, videos)"},{"_id":"6147867277a9d1d27e000795","treeId":"655a38b74450703f0b0004a4","seq":17417450,"position":1,"parentId":"61eb5877e0ec83272c000483","content":"Weekend session: May 11"},{"_id":"62b6cd0fa7ef3106690007f5","treeId":"655a38b74450703f0b0004a4","seq":17417604,"position":5,"parentId":"62f86df4118b3581530002a0","content":"**Homework**\n\nSelf-study remainder of antenna chapter [Chapter n]\n\n\nWatch various videos\n\nChapter 9 for next class\n"},{"_id":"63cbe56278d65a6bc3000199","treeId":"655a38b74450703f0b0004a4","seq":17334336,"position":0.1875,"parentId":"62b6cd0fa7ef3106690007f5","content":"Video: [secret life of machines: radio](https://www.youtube.com/watch?v=2roG4jIjvEk) This half-hour video is worth watching beginning to end."},{"_id":"61c389e101c50ff7b6000b45","treeId":"655a38b74450703f0b0004a4","seq":17334353,"position":0.375,"parentId":"62b6cd0fa7ef3106690007f5","content":"Here is a study guide for the various [block diagrams found in the exam](http://homepage.usask.ca/~bdb368/ham/basic/block_diagrams/index.html). In a basic qualification exam, there will be one question about each block diagram."},{"_id":"61c3e16a01c50ff7b6000b3c","treeId":"655a38b74450703f0b0004a4","seq":17334356,"position":0.75,"parentId":"62b6cd0fa7ef3106690007f5","content":"This is a very good and very clear [army training video on FM modulation](https://www.youtube.com/watch?v=D65KXwfDs3s)."},{"_id":"6442406a9a63635172000706","treeId":"655a38b74450703f0b0004a4","seq":17293927,"position":1,"parentId":"61c3e16a01c50ff7b6000b3c","content":"See also: \n\nhttps://www.youtube.com/watch?v=xn6lzrMJUDs (via VE7MHW)"},{"_id":"644246aa9a63635172000704","treeId":"655a38b74450703f0b0004a4","seq":17334360,"position":2,"parentId":"62b6cd0fa7ef3106690007f5","content":"Here is an [animated video of how a crystal radio works.](https://www.youtube.com/watch?v=0-PParSmwtE)\n\n(It also has a segment on how AM is modulated, then demodulated in the set)"},{"_id":"61c3d12e01c50ff7b6000b3f","treeId":"655a38b74450703f0b0004a4","seq":17294358,"position":3,"parentId":"62b6cd0fa7ef3106690007f5","content":"Extra credit:\n\n* [All About Circuits page on radio](https://www.allaboutcircuits.com/textbook/semiconductors/chpt-9/radio-circuits/)\n* Video: [adding waves together](https://www.youtube.com/watch?v=ds0cmAV-Yek)"},{"_id":"61ffa02111f5ef04db00055c","treeId":"655a38b74450703f0b0004a4","seq":17259049,"position":0.88134765625,"parentId":"654fb37b305a6842700000cf","content":"## Class 7: Transmitters (ch 13), more block diagrams (ch 13)"},{"_id":"62f85971118b3581530002a9","treeId":"655a38b74450703f0b0004a4","seq":17486437,"position":1.78125,"parentId":"61ffa02111f5ef04db00055c","content":"### **Transmitters**\n* oscillators\n\n[ ] build AM transmitter\n[ ] various demos involving transmitter\n\n* filters, in the context of transmitters"},{"_id":"61eae66649b96d906f000382","treeId":"655a38b74450703f0b0004a4","seq":17261234,"position":0.5,"parentId":"62f85971118b3581530002a9","content":"[the circuit](https://sci-toys.com/scitoys/scitoys/radio/am_transmitter.html)"},{"_id":"60fcbb9254ad3c11130004fe","treeId":"655a38b74450703f0b0004a4","seq":17474631,"position":0.75,"parentId":"62f85971118b3581530002a9","content":"[datasheet for crystal oscillator](https://www.opel.ece.vt.edu/reference/DataSheets/MCO-1510A-szgreat.pdf)"},{"_id":"60fb627961de4adcbe0004ff","treeId":"655a38b74450703f0b0004a4","seq":17476602,"position":0.875,"parentId":"62f85971118b3581530002a9","content":"[iphone pinout](https://apple.stackexchange.com/questions/135967/can-i-use-non-apple-headphones-with-an-iphone)"},{"_id":"61eaeb2ae0ec83272c000487","treeId":"655a38b74450703f0b0004a4","seq":17476600,"position":2,"parentId":"62f85971118b3581530002a9","content":"More on quartz oscillators [advanced]","deleted":false},{"_id":"61eae756e0ec83272c000488","treeId":"655a38b74450703f0b0004a4","seq":17476596,"position":0.25,"parentId":"61eaeb2ae0ec83272c000487","content":"[waveform of quartz oscillator](https://electronics.stackexchange.com/questions/58223/output-of-oscillator-expected-to-be-square-wave-but-looks-sinusoidal)"},{"_id":"60f8f01661de4adcbe000500","treeId":"655a38b74450703f0b0004a4","seq":17476594,"position":0.5,"parentId":"61eaeb2ae0ec83272c000487","content":"[quartz oscillator circuits](http://www.oscilent.com/esupport/TechSupport/ReviewPapers/IntroQuartz/vigtypes.htm)"},{"_id":"61eaeff5e0ec83272c000485","treeId":"655a38b74450703f0b0004a4","seq":17476587,"position":1,"parentId":"61eaeb2ae0ec83272c000487","content":"![](https://circuitdigest.com/sites/default/files/projectimage_tut/Quartz-Crystal-Oscillator.png)\n\nfrom https://circuitdigest.com/tutorial/quartz-crystal-oscillator"},{"_id":"6138fef3a2d37115d40004fb","treeId":"655a38b74450703f0b0004a4","seq":17431359,"position":4,"parentId":"62f85971118b3581530002a9","content":"filtering, in the context of mixing and transmitters"},{"_id":"60ed12b961de4adcbe000835","treeId":"655a38b74450703f0b0004a4","seq":17486438,"position":1.86328125,"parentId":"61ffa02111f5ef04db00055c","content":"### **diodes**\n* terminal names\n* zener diodes\n* rectifiers\n* LEDs\n* biasing"},{"_id":"61eb6a79e0ec83272c000480","treeId":"655a38b74450703f0b0004a4","seq":17486439,"position":1.875,"parentId":"61ffa02111f5ef04db00055c","content":"### **active components:**\ntubes, semiconductors, transistors"},{"_id":"60f8e44861de4adcbe000824","treeId":"655a38b74450703f0b0004a4","seq":17476612,"position":0.2500025,"parentId":"61eb6a79e0ec83272c000480","content":"[bipolar transistors](http://homepage.usask.ca/~bdb368/ham/basic/block_diagrams/bipolar_transistor_explanation.html)\n\n[field effect transistors](http://homepage.usask.ca/~bdb368/ham/basic/block_diagrams/field_effect_transistor_explanation.html)\n\n[vacuum tubes](http://homepage.usask.ca/~bdb368/ham/basic/block_diagrams/vacuum_tube_explanation.html)"},{"_id":"60ecee8461de4adcbe000838","treeId":"655a38b74450703f0b0004a4","seq":17486478,"position":0.5000025,"parentId":"61eb6a79e0ec83272c000480","content":"* two types of each: NPN & PNP, or N-channel and P-channel"},{"_id":"60ecea4961de4adcbe000839","treeId":"655a38b74450703f0b0004a4","seq":17486477,"position":0.6250025,"parentId":"61eb6a79e0ec83272c000480","content":"* terminal names (table 9-1, page 9-14)"},{"_id":"60ecdfd161de4adcbe00083a","treeId":"655a38b74450703f0b0004a4","seq":17486480,"position":0.6875025,"parentId":"61eb6a79e0ec83272c000480","content":"* FETs are voltage-controlled, BJTs are current-controlled (roughtly)"},{"_id":"60ecd28561de4adcbe00083c","treeId":"655a38b74450703f0b0004a4","seq":17486540,"position":0.7187525,"parentId":"61eb6a79e0ec83272c000480","content":"Triode tubes\n\n* Layout\n\ntubes/valves vs transistors: it's basically about power and heat. Vacuum tubes also require high voltages."},{"_id":"60f8d07d61de4adcbe000825","treeId":"655a38b74450703f0b0004a4","seq":17485105,"position":0.7500025,"parentId":"61eb6a79e0ec83272c000480","content":"(Advanced)"},{"_id":"644164859a6363517200070a","treeId":"655a38b74450703f0b0004a4","seq":17485104,"position":1,"parentId":"60f8d07d61de4adcbe000825","content":"an amazing endless rant on [how transistors work](http://amasci.com/amateur/transis.html)"},{"_id":"60ed1e5661de4adcbe00082a","treeId":"655a38b74450703f0b0004a4","seq":17486440,"position":2.15625,"parentId":"61ffa02111f5ef04db00055c","content":"### **amplifiers**"},{"_id":"60ed1e2861de4adcbe00082b","treeId":"655a38b74450703f0b0004a4","seq":17486297,"position":1,"parentId":"60ed1e5661de4adcbe00082a","content":"amplifier characteristic curve, non-linearity"},{"_id":"60ed1b3761de4adcbe00082d","treeId":"655a38b74450703f0b0004a4","seq":17486309,"position":2,"parentId":"60ed1e5661de4adcbe00082a","content":"types of amplifiers (RF signal, audio, power)"},{"_id":"60ed164361de4adcbe000830","treeId":"655a38b74450703f0b0004a4","seq":17486321,"position":3,"parentId":"60ed1e5661de4adcbe00082a","content":"frequency range - RF vs AF"},{"_id":"60ed15d961de4adcbe000831","treeId":"655a38b74450703f0b0004a4","seq":17486323,"position":4,"parentId":"60ed1e5661de4adcbe00082a","content":"voltage vs current vs power amplifers"},{"_id":"60ed14fa61de4adcbe000832","treeId":"655a38b74450703f0b0004a4","seq":17486324,"position":5,"parentId":"60ed1e5661de4adcbe00082a","content":"gain"},{"_id":"60ed13aa61de4adcbe000833","treeId":"655a38b74450703f0b0004a4","seq":17486328,"position":6,"parentId":"60ed1e5661de4adcbe00082a","content":"linearity"},{"_id":"60ed138a61de4adcbe000834","treeId":"655a38b74450703f0b0004a4","seq":17486330,"position":7,"parentId":"60ed1e5661de4adcbe00082a","content":"distortion"},{"_id":"61a28a1314cd24a9700003cb","treeId":"655a38b74450703f0b0004a4","seq":17487056,"position":2.4375,"parentId":"61ffa02111f5ef04db00055c","content":"### **power supplies**\n\n[power supply block diagram](http://homepage.usask.ca/~bdb368/ham/basic/block_diagrams/regulated_power_supply_explanation.html)\n\n* transformer\n* rectifier\n* filter\n* regulator"},{"_id":"61c386c801c50ff7b6000b46","treeId":"655a38b74450703f0b0004a4","seq":17476662,"position":3,"parentId":"61ffa02111f5ef04db00055c","content":"### **Homework:**\n"},{"_id":"60f8cd8f61de4adcbe000827","treeId":"655a38b74450703f0b0004a4","seq":17476665,"position":0.75,"parentId":"61c386c801c50ff7b6000b46","content":"Online:\n\n[block diagram study page](http://homepage.usask.ca/~bdb368/ham/basic/block_diagrams/index.html)\n* [FM transmitter](http://homepage.usask.ca/~bdb368/ham/basic/block_diagrams/frequency_modulation_transmitter_explanation.html)\n* [SSB transmitter](http://homepage.usask.ca/~bdb368/ham/basic/block_diagrams/single_sideband_transmitter_explanation.html)"},{"_id":"64424d489a63635172000702","treeId":"655a38b74450703f0b0004a4","seq":17476661,"position":1,"parentId":"61c386c801c50ff7b6000b46","content":"Videos:\n\n* [Old video from Westinghouse about vacuum tubes](https://www.youtube.com/watch?v=MOioyzuGOqo). "},{"_id":"61c3dd0c01c50ff7b6000b3e","treeId":"655a38b74450703f0b0004a4","seq":17334367,"position":4,"parentId":"61ffa02111f5ef04db00055c","content":"Deferred to later"},{"_id":"62f86ca8118b3581530002a1","treeId":"655a38b74450703f0b0004a4","seq":17293945,"position":1,"parentId":"61c3dd0c01c50ff7b6000b3e","content":"mixing"},{"_id":"62c6cdaf3ed807f8e00002ad","treeId":"655a38b74450703f0b0004a4","seq":17293952,"position":1,"parentId":"62f86ca8118b3581530002a1","content":"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."},{"_id":"642931eb65aa2d1b21000176","treeId":"655a38b74450703f0b0004a4","seq":17293958,"position":2,"parentId":"62f86ca8118b3581530002a1","content":"[ ] GDO as BFO at 1.6 MHz (demo)","deleted":false},{"_id":"62c6ab893ed807f8e00002ae","treeId":"655a38b74450703f0b0004a4","seq":17032055,"position":1,"parentId":"642931eb65aa2d1b21000176","content":"uses GDO, HT, signal generator"},{"_id":"61eb9abbe0ec83272c00047e","treeId":"655a38b74450703f0b0004a4","seq":17586352,"position":0.890869140625,"parentId":"654fb37b305a6842700000cf","content":"## Class 8: Station Components (ch. 11), Interference & Suppression (ch 15) "},{"_id":"60ed491761de4adcbe000829","treeId":"655a38b74450703f0b0004a4","seq":17586379,"position":1.5,"parentId":"61eb9abbe0ec83272c00047e","content":"### **Station components**"},{"_id":"60ecf21a61de4adcbe000837","treeId":"655a38b74450703f0b0004a4","seq":17486475,"position":1,"parentId":"60ed491761de4adcbe000829","content":"[HF station](http://homepage.usask.ca/~bdb368/ham/basic/block_diagrams/placement_of_parts_in_an_hf_station_explanation.html) block diagram\n\n[digital station ](http://homepage.usask.ca/~bdb368/ham/basic/block_diagrams/digital_system_explanation.html) block diagram"},{"_id":"61a28cdd14cd24a9700003ca","treeId":"655a38b74450703f0b0004a4","seq":17586381,"position":2,"parentId":"60ed491761de4adcbe000829","content":"[HF station block diagram](http://homepage.usask.ca/~bdb368/ham/basic/block_diagrams/placement_of_parts_in_an_hf_station_explanation.html)"},{"_id":"61a2740c14cd24a9700003d2","treeId":"655a38b74450703f0b0004a4","seq":17586403,"position":1.75,"parentId":"61eb9abbe0ec83272c00047e","content":"digital stuff"},{"_id":"61a273db14cd24a9700003d3","treeId":"655a38b74450703f0b0004a4","seq":17337854,"position":1,"parentId":"61a2740c14cd24a9700003d2","content":"[digital system block diagram](http://homepage.usask.ca/~bdb368/ham/basic/block_diagrams/digital_system_explanation.html)"},{"_id":"61a1d0e714cd24a9700003e4","treeId":"655a38b74450703f0b0004a4","seq":17338414,"position":2,"parentId":"61eb9abbe0ec83272c00047e","content":"[intermod](https://en.wikipedia.org/wiki/Intermodulation)"},{"_id":"61a1cea214cd24a9700003e5","treeId":"655a38b74450703f0b0004a4","seq":17338416,"position":3,"parentId":"61eb9abbe0ec83272c00047e","content":"[harmonic distortion](https://en.wikipedia.org/wiki/Distortion#Harmonic_distortion)"},{"_id":"603324bc3736424504000553","treeId":"655a38b74450703f0b0004a4","seq":17586871,"position":1,"parentId":"61a1cea214cd24a9700003e5","content":"(advanced) the following page shows that harmonic distortion comes from non-linearity in RF amps\n\nhttp://www.sharetechnote.com/html/RF_Amplifier.html"},{"_id":"61eba95ae0ec83272c00047c","treeId":"655a38b74450703f0b0004a4","seq":17259193,"position":0.898193359375,"parentId":"654fb37b305a6842700000cf","content":"## Class n+1: (weekend?) Regulations and Operation\nSafety (self-study)"},{"_id":"654fb1da305a6842700000d1","treeId":"655a38b74450703f0b0004a4","seq":17259023,"position":0.99999,"parentId":"61eba95ae0ec83272c00047c","content":"## Regulations"},{"_id":"6375144a5d0fbe476c0001dc","treeId":"655a38b74450703f0b0004a4","seq":16821125,"position":0.28125,"parentId":"654fb1da305a6842700000d1","content":"There is [a chart](https://www.ic.gc.ca/eic/site/smt-gst.nsf/vwapj/2018_Canadian_Radio_Spectrum_Chart.PDF/$FILE/2018_Canadian_Radio_Spectrum_Chart.PDF) that illustrates the spectrum allocations in Canada."},{"_id":"653c6c17e8acad334d00011f","treeId":"655a38b74450703f0b0004a4","seq":16821158,"position":1,"parentId":"6375144a5d0fbe476c0001dc","content":"The chart is based on the [2018 table of allocations](https://www.ic.gc.ca/eic/site/smt-gst.nsf/eng/sf10759.html), which is [quite long](https:/www.ic.gc.ca/eic/site/smt-gst.nsf/eng/h_sf01678.html). In fact it is so long it is divided into [many different sections](https://www.ic.gc.ca/eic/site/smt-gst.nsf/eng/sf08748.html)."},{"_id":"654fadff305a6842700000d2","treeId":"655a38b74450703f0b0004a4","seq":16677094,"position":1,"parentId":"654fb1da305a6842700000d1","content":"Regulatory stuff can and should be self-studied throughout the course"},{"_id":"6365cf93d532bf36e800021e","treeId":"655a38b74450703f0b0004a4","seq":17259024,"position":1.99998,"parentId":"61eba95ae0ec83272c00047c","content":"### Operations"},{"_id":"654fa8f3305a6842700000d4","treeId":"655a38b74450703f0b0004a4","seq":16833235,"position":1,"parentId":"6365cf93d532bf36e800021e","content":"Operating procedures"},{"_id":"642e23e798c90a673700066f","treeId":"655a38b74450703f0b0004a4","seq":16833238,"position":2,"parentId":"6365cf93d532bf36e800021e","content":"[CW Operation Video](https://www.youtube.com/watch?v=GvQ_UnePS7w)"},{"_id":"63f3b93fbbcdbc7cf4000362","treeId":"655a38b74450703f0b0004a4","seq":16833241,"position":3,"parentId":"6365cf93d532bf36e800021e","content":"Getting started on HF"},{"_id":"63f3b8febbcdbc7cf4000363","treeId":"655a38b74450703f0b0004a4","seq":16732006,"position":1,"parentId":"63f3b93fbbcdbc7cf4000362","content":"https://www.ebay.ca/sch/i.html?_odkw=100+watt+hf+transceiver&_udlo=200&_udhi=500&_mPrRngCbx=1&_osacat=0&_from=R40&_trksid=m570.l1313&_nkw=+hf+transceiver&_sacat=0"},{"_id":"63f3b7a4bbcdbc7cf4000364","treeId":"655a38b74450703f0b0004a4","seq":16732009,"position":2,"parentId":"63f3b93fbbcdbc7cf4000362","content":"https://hackaday.com/2016/06/02/the-minima-is-an-all-band-hf-transceiver-for-under-100/"},{"_id":"63f3b765bbcdbc7cf4000365","treeId":"655a38b74450703f0b0004a4","seq":16732010,"position":3,"parentId":"63f3b93fbbcdbc7cf4000362","content":"https://www.lowcosthamradio.com/"},{"_id":"63f3b705bbcdbc7cf4000366","treeId":"655a38b74450703f0b0004a4","seq":16732013,"position":4,"parentId":"63f3b93fbbcdbc7cf4000362","content":"https://www.reddit.com/r/amateurradio/comments/2w8030/what_is_the_absolute_cheapest_hf_rig_available/"},{"_id":"6243aaad3c4d420b7b000360","treeId":"655a38b74450703f0b0004a4","seq":17140720,"position":4,"parentId":"6365cf93d532bf36e800021e","content":"[video on various digital modes](https://www.youtube.com/watch?v=tXLXe9C7JX8)"},{"_id":"63685e3553b88b9b4600039a","treeId":"655a38b74450703f0b0004a4","seq":17553407,"position":0.9007568359375,"parentId":"654fb37b305a6842700000cf","content":"## Things to memorize"},{"_id":"6313df1007d2338c22000272","treeId":"655a38b74450703f0b0004a4","seq":17553377,"position":1,"parentId":"63685e3553b88b9b4600039a","content":"* [NATO phonetic alphabet](https://en.wikipedia.org/wiki/NATO_phonetic_alphabet)\n\n* Q-signals (pg 12-2) \n\n* Band limits"},{"_id":"60eab2037d14cf55a5000405","treeId":"655a38b74450703f0b0004a4","seq":17487064,"position":1.8270263671875,"parentId":"654fb37b305a6842700000cf","content":"Everything Else"},{"_id":"642932cc65aa2d1b21000171","treeId":"655a38b74450703f0b0004a4","seq":17487065,"position":1,"parentId":"60eab2037d14cf55a5000405","content":"## Practical Exercises"},{"_id":"6429328765aa2d1b21000172","treeId":"655a38b74450703f0b0004a4","seq":16700167,"position":1,"parentId":"642932cc65aa2d1b21000171","content":"Crystal Receiver"},{"_id":"6429325865aa2d1b21000173","treeId":"655a38b74450703f0b0004a4","seq":16700168,"position":1,"parentId":"6429328765aa2d1b21000172","content":"https://en.wikipedia.org/wiki/Crystal_radio"},{"_id":"6429110565aa2d1b21000177","treeId":"655a38b74450703f0b0004a4","seq":16700221,"position":2,"parentId":"6429328765aa2d1b21000172","content":"[point contact diode](https://www.google.com/search?q=point+contact+diode&source=lnms&tbm=isch&sa=X&ved=0ahUKEwjlvI2prbXgAhXYCTQIHZggCPAQ_AUIDigB&biw=1532&bih=699)"},{"_id":"6428e6aa65aa2d1b21000178","treeId":"655a38b74450703f0b0004a4","seq":16700270,"position":3,"parentId":"6429328765aa2d1b21000172","content":"https://sci-toys.com/scitoys/scitoys/radio/radio.html"},{"_id":"6428dae565aa2d1b21000179","treeId":"655a38b74450703f0b0004a4","seq":16700276,"position":1,"parentId":"6428e6aa65aa2d1b21000178","content":"[coil calculator](https://sci-toys.com/scitoys/scitoys/radio/xtal.html)"},{"_id":"6421829865aa2d1b21000183","treeId":"655a38b74450703f0b0004a4","seq":16704075,"position":3.5,"parentId":"6429328765aa2d1b21000172","content":"[more useful information](https://rimstar.org/equip/crystal_radios.htm)"},{"_id":"63c4ddbd78d65a6bc30001a8","treeId":"655a38b74450703f0b0004a4","seq":16760760,"position":3.75,"parentId":"6429328765aa2d1b21000172","content":"[Rimstar's crystal radios page](https://rimstar.org/equip/crystal_radios.htm)"},{"_id":"6421d2a365aa2d1b2100017e","treeId":"655a38b74450703f0b0004a4","seq":16703914,"position":4,"parentId":"6429328765aa2d1b21000172","content":"[images of older crystal radios](https://www.google.com/search?q=polyfilm+capacitor+crystal+radio&tbm=isch&tbs=rimg:CTQK7EjpfdgWIjjbOx0rPCoSfEBuzRRs5zYAlrndKCXp-kDy1b3OpYaB2Vn0dUa6RXPgwyALsQx5WhadmMm1OXFNBSoSCds7HSs8KhJ8EcVu3ofbvP2FKhIJQG7NFGznNgARIJ7VF6miaQUqEgmWud0oJen6QBGWhQ1xR3LPyyoSCfLVvc6lhoHZEX7GndXur7KwKhIJWfR1RrpFc-ARzUIs7niO7KQqEgnDIAuxDHlaFhHSYprNY6uoxyoSCZ2YybU5cU0FEee0PoohnDv5&tbo=u&sa=X&ved=2ahUKEwj77bG-yrTgAhWUN30KHYGMCwEQ9C96BAgBEBg&biw=1273&bih=699&dpr=1#imgrc=v0bM1_I-OQy5oM:)"},{"_id":"6421cfc665aa2d1b2100017f","treeId":"655a38b74450703f0b0004a4","seq":16703923,"position":5,"parentId":"6429328765aa2d1b21000172","content":"[images of polyfilm variable capacitor in crystal radios](https://www.google.com/search?q=polyfilm+capacitor+crystal+radio&source=lnms&tbm=isch&sa=X&ved=0ahUKEwj2u_DRvbTgAhWJ_p8KHSOsD_sQ_AUIDigB&biw=1273&bih=699#imgrc=jC6WfBRqlz2YBM:)"},{"_id":"63cae39d78d65a6bc30001a1","treeId":"655a38b74450703f0b0004a4","seq":16757498,"position":6,"parentId":"6429328765aa2d1b21000172","content":"[coupling to headphones](https://rimstar.org/equip/use_iphone_earbuds_earpods_with_crystal_radio.htm)"},{"_id":"63c4d05a78d65a6bc30001a9","treeId":"655a38b74450703f0b0004a4","seq":16760765,"position":7,"parentId":"6429328765aa2d1b21000172","content":"[many more crystal radio sets than may be healthy](http://makearadio.com/crystal/index.php)"},{"_id":"639a930c5d0fbe476c0001b6","treeId":"655a38b74450703f0b0004a4","seq":16830222,"position":8,"parentId":"6429328765aa2d1b21000172","content":"[irony of AM radio](https://www.youtube.com/watch?v=VY6PAkLG2p4) (content warning)"},{"_id":"642d3703a230cd1b5000069c","treeId":"655a38b74450703f0b0004a4","seq":16830204,"position":9,"parentId":"6429328765aa2d1b21000172","content":"[building fahnestock clips](http://onetuberadio.com/2017/12/14/1927-soviet-fahnestock-clips/)"},{"_id":"6429324a65aa2d1b21000174","treeId":"655a38b74450703f0b0004a4","seq":16700169,"position":2,"parentId":"642932cc65aa2d1b21000171","content":"Audio Amplifier"},{"_id":"63767aef5d0fbe476c0001bd","treeId":"655a38b74450703f0b0004a4","seq":16818199,"position":0.03125,"parentId":"6429324a65aa2d1b21000174","content":"**Basic Certificate**"},{"_id":"637685815d0fbe476c0001bb","treeId":"655a38b74450703f0b0004a4","seq":16818229,"position":0.0390625,"parentId":"6429324a65aa2d1b21000174","content":"For the basic certificate, it is sufficient to study a simple **single-transistor power amplifier**.\n\nWe 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."},{"_id":"637672ae5d0fbe476c0001bf","treeId":"655a38b74450703f0b0004a4","seq":16818238,"position":0.5,"parentId":"637685815d0fbe476c0001bb","content":"The following links serve as background for the in-class exercise (to be described elsewhere):"},{"_id":"64217fa365aa2d1b21000184","treeId":"655a38b74450703f0b0004a4","seq":16818088,"position":1,"parentId":"637685815d0fbe476c0001bb","content":"[single-transistor amplifier for crystal sets, from \"Rimstar\"](https://rimstar.org/equip/crystal_radio_amplifier_for_earphone.htm)"},{"_id":"63d005c9bbcdbc7cf400094a","treeId":"655a38b74450703f0b0004a4","seq":16818099,"position":2,"parentId":"637685815d0fbe476c0001bb","content":"[Funway single transistor amp](http://www.funwayelectronics.com/contents/en-us/d9072_One_Transistor_Amplifier.html)"},{"_id":"63ce903583aa9ba516000197","treeId":"655a38b74450703f0b0004a4","seq":16818108,"position":3,"parentId":"637685815d0fbe476c0001bb","content":"[various circuits](https://www.hackster.io/jwzumwalt/single-transistor-audio-amp-32033a)"},{"_id":"63b7b176dbcac9fb760001b3","treeId":"655a38b74450703f0b0004a4","seq":16818143,"position":3.5,"parentId":"637685815d0fbe476c0001bb","content":"[yet another purported example](https://circuitdigest.com/electronic-circuits/simple-preamplifier-circuit-diagram)"},{"_id":"63b7addfdbcac9fb760001b4","treeId":"655a38b74450703f0b0004a4","seq":16818130,"position":4,"parentId":"637685815d0fbe476c0001bb","content":"[and another](http://hackaweek.com/hacks/?p=327)"},{"_id":"63b7aa64dbcac9fb760001b5","treeId":"655a38b74450703f0b0004a4","seq":16818152,"position":5,"parentId":"637685815d0fbe476c0001bb","content":"[and another](https://electronics.stackexchange.com/questions/32779/common-emitter-audio-amplifier)"},{"_id":"63c4e3d3d318abafbb0001a6","treeId":"655a38b74450703f0b0004a4","seq":16818179,"position":6,"parentId":"637685815d0fbe476c0001bb","content":"[single-transistor amplifiers, in detail](https://wiki.analog.com/university/courses/electronics/text/chapter-9)"},{"_id":"63767a805d0fbe476c0001be","treeId":"655a38b74450703f0b0004a4","seq":16818200,"position":0.046875,"parentId":"6429324a65aa2d1b21000174","content":"**Advanced Certificate**"},{"_id":"637687395d0fbe476c0001b8","treeId":"655a38b74450703f0b0004a4","seq":16818218,"position":0.0546875,"parentId":"6429324a65aa2d1b21000174","content":"Two-stage power amplifier"},{"_id":"637686865d0fbe476c0001b9","treeId":"655a38b74450703f0b0004a4","seq":16818081,"position":1,"parentId":"637687395d0fbe476c0001b8","content":"[buffer amplifiers](https://en.wikipedia.org/wiki/Buffer_amplifier#Single-transistor_circuits)"},{"_id":"63c4e5cbd318abafbb0001a5","treeId":"655a38b74450703f0b0004a4","seq":16818202,"position":0.0625,"parentId":"6429324a65aa2d1b21000174","content":"[classes of amplifiers](https://www.electronics-tutorials.ws/amplifier/amplifier-classes.html)"},{"_id":"63d006e0bbcdbc7cf4000949","treeId":"655a38b74450703f0b0004a4","seq":16818191,"position":0.078125,"parentId":"6429324a65aa2d1b21000174","content":"[Single-Transistor amplifier from Sparkfun](https://learn.sparkfun.com/tutorials/transistors/applications-ii-amplifiers)"},{"_id":"63d00184bbcdbc7cf400094b","treeId":"655a38b74450703f0b0004a4","seq":16760963,"position":1,"parentId":"63d006e0bbcdbc7cf4000949","content":"[common emitter schematic](https://cdn.sparkfun.com/assets/learn_tutorials/1/9/3/common-emitter-speaker-amplifier-02.png)"},{"_id":"63ccea8283aa9ba516000198","treeId":"655a38b74450703f0b0004a4","seq":16760756,"position":2,"parentId":"63d006e0bbcdbc7cf4000949","content":"[detailed explanation of common-emitter amplifiers](https://www.electronics-tutorials.ws/amplifier/amp_2.html)"},{"_id":"63c4e0d9d318abafbb0001a7","treeId":"655a38b74450703f0b0004a4","seq":16760758,"position":2.5,"parentId":"63d006e0bbcdbc7cf4000949","content":"[emitter resistance](https://www.electronics-tutorials.ws/amplifier/emitter-resistance.html)"},{"_id":"63c4e913d318abafbb0001a2","treeId":"655a38b74450703f0b0004a4","seq":16760750,"position":3,"parentId":"63d006e0bbcdbc7cf4000949","content":"[Troubleshooting this circuit](https://electronics.stackexchange.com/questions/211500/how-are-the-resistor-values-r1-and-r2-calculated-for-a-transistor-amplifier-that)\n>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."},{"_id":"63bf1fc769f4afee5f0001aa","treeId":"655a38b74450703f0b0004a4","seq":16765805,"position":3.5,"parentId":"63d006e0bbcdbc7cf4000949","content":"Another person with the same problem: [Why can't class A amp drive 8 ohm speaker with just one BJT?](https://electronics.stackexchange.com/questions/368614/why-cant-class-a-amp-drive-8-ohm-speaker-with-just-one-bjt)"},{"_id":"63c4e694d318abafbb0001a4","treeId":"655a38b74450703f0b0004a4","seq":16818183,"position":0.09375,"parentId":"6429324a65aa2d1b21000174","content":"Any discussion of transistor amplifers inevitably ends up being a discussion on **Biasing Transistors**, discussed in the links that follow.\n"},{"_id":"63b7fc19dbcac9fb760001af","treeId":"655a38b74450703f0b0004a4","seq":16765761,"position":0.5,"parentId":"63c4e694d318abafbb0001a4","content":"The propoer way to do it is described at this page about \n[biasing transistors in excruciating detail](https://www.electronics-tutorials.ws/amplifier/transistor-biasing.html)"},{"_id":"63b7fe20dbcac9fb760001ae","treeId":"655a38b74450703f0b0004a4","seq":16765769,"position":0.75,"parentId":"63c4e694d318abafbb0001a4","content":"But after some [some hand-wringing about basic electronics, from hackaday](https://hackaday.com/2018/04/06/wont-somebody-please-think-of-the-transistors/) some folks had the bright idea to write about it in a bit more accessble way..."},{"_id":"63b805fadbcac9fb760001ac","treeId":"655a38b74450703f0b0004a4","seq":16765777,"position":2,"parentId":"63c4e694d318abafbb0001a4","content":"So here we have a discussion about [common-emitter amplifers, from hackaday](https://hackaday.com/2018/05/04/biasing-that-transistor-part-1-the-common-emitter-amplifier/) that includes some helpful rules of thumb:"},{"_id":"63b801a8dbcac9fb760001ad","treeId":"655a38b74450703f0b0004a4","seq":16765789,"position":1,"parentId":"63b805fadbcac9fb760001ac","content":">For example:\n* Pick a collector resistor using Ohm’s Law to deliver the **desired maximum current when the transistor is saturated**, \n* then make a few guesses with the bias resistors by making their **total value over 10 times the collector resistor** and \n* the ratio of **upper** bias resistor to **lower** one being about **2 to 1**. "},{"_id":"63b8098adbcac9fb760001ab","treeId":"655a38b74450703f0b0004a4","seq":16818185,"position":3,"parentId":"63c4e694d318abafbb0001a4","content":"See also this discussion about [biasing common-base transistor amplifers](https://hackaday.com/2018/05/11/biasing-that-transistor-the-common-base-amplifier/)."},{"_id":"63767f775d0fbe476c0001bc","treeId":"655a38b74450703f0b0004a4","seq":16818204,"position":2,"parentId":"6429324a65aa2d1b21000174","content":"[lovingly hand-crafted page on transistor circuits](http://www.talkingelectronics.com/projects/TheTransistorAmplifier/TheTransistorAmplifier-P1.html)"},{"_id":"642d364aa230cd1b5000069d","treeId":"655a38b74450703f0b0004a4","seq":16830219,"position":3,"parentId":"6429324a65aa2d1b21000174","content":"[capacitor markings for various values](http://www.radiodaze.com/capacitor-markings/)"},{"_id":"63b7f3b5dbcac9fb760001b0","treeId":"655a38b74450703f0b0004a4","seq":16765793,"position":2.5,"parentId":"642932cc65aa2d1b21000171","content":"Transistor Radio"},{"_id":"63b7f38ddbcac9fb760001b1","treeId":"655a38b74450703f0b0004a4","seq":16765840,"position":1,"parentId":"63b7f3b5dbcac9fb760001b0","content":"Here is an article from hackaday about [a book on making a transistor radio](https://hackaday.com/2017/02/03/books-you-should-read-making-a-transistor-radio/). Here is [the whole book in a web viwer](https://archive.org/details/MakingATransistorRadio-LadybirdBook), and here is [the PDF](https://ia800409.us.archive.org/24/items/MakingATransistorRadio-LadybirdBook/lb-transistor.pdf)."},{"_id":"63b7e4b1dbcac9fb760001b2","treeId":"655a38b74450703f0b0004a4","seq":16765818,"position":2,"parentId":"63b7f3b5dbcac9fb760001b0","content":"[\"three-penny radio\"](https://sci-toys.com/scitoys/scitoys/radio/three_penny/three_penny.html)"},{"_id":"6429320f65aa2d1b21000175","treeId":"655a38b74450703f0b0004a4","seq":16700172,"position":3,"parentId":"642932cc65aa2d1b21000171","content":"Transmitter"},{"_id":"6428d49c65aa2d1b2100017a","treeId":"655a38b74450703f0b0004a4","seq":16700285,"position":1,"parentId":"6429320f65aa2d1b21000175","content":"[three-componenent AM transmitter](https://sci-toys.com/scitoys/scitoys/radio/am_transmitter.html)"},{"_id":"64218b0e65aa2d1b21000181","treeId":"655a38b74450703f0b0004a4","seq":16704069,"position":5,"parentId":"642932cc65aa2d1b21000171","content":"Reference Information "},{"_id":"64218ae765aa2d1b21000182","treeId":"655a38b74450703f0b0004a4","seq":16704071,"position":1,"parentId":"64218b0e65aa2d1b21000181","content":"[electrostatic smoke precipitator](https://rimstar.org/science_electronics_projects/electrostatic_precipitator_smoke_precipitator_simple.htm)"},{"_id":"654fb254305a6842700000d0","treeId":"655a38b74450703f0b0004a4","seq":17487066,"position":2,"parentId":"60eab2037d14cf55a5000405","content":"## General Technical Content"},{"_id":"64425faa9a636351720006fe","treeId":"655a38b74450703f0b0004a4","seq":16887561,"position":0.25,"parentId":"654fb254305a6842700000d0","content":"electronics, etc, following the map I have drawn out on paper. Major sections so far are\n* electromagnetism, fields, electromagnetic circuits, electromagnetic waves"},{"_id":"6442601a9a636351720006fd","treeId":"655a38b74450703f0b0004a4","seq":16887566,"position":0.5,"parentId":"64425faa9a636351720006fe","content":"The electromagnetic specrum"},{"_id":"64421e129a63635172000707","treeId":"655a38b74450703f0b0004a4","seq":16670923,"position":2,"parentId":"6442601a9a636351720006fd","content":"https://youtu.be/xn6lzrMJUDs?t=626"},{"_id":"6325afefc82956ebf2000242","treeId":"655a38b74450703f0b0004a4","seq":16895730,"position":0.375,"parentId":"654fb254305a6842700000d0","content":"* conductors, insulators, dielectrics, semiconductors"},{"_id":"644266249a636351720006fa","treeId":"655a38b74450703f0b0004a4","seq":16895729,"position":0.5,"parentId":"654fb254305a6842700000d0","content":"* voltage and resistance and power"},{"_id":"6332609d4ac6fd1762000755","treeId":"655a38b74450703f0b0004a4","seq":16895361,"position":0.03125,"parentId":"644266249a636351720006fa","content":"DC power"},{"_id":"633261024ac6fd1762000754","treeId":"655a38b74450703f0b0004a4","seq":16887554,"position":0.0625,"parentId":"644266249a636351720006fa","content":"AC power"},{"_id":"644267b29a636351720006f6","treeId":"655a38b74450703f0b0004a4","seq":16887553,"position":0.125,"parentId":"644266249a636351720006fa","content":"The Time Domain"},{"_id":"644268439a636351720006f5","treeId":"655a38b74450703f0b0004a4","seq":16670899,"position":1.625,"parentId":"654fb254305a6842700000d0","content":"The Frequency Domain, audio frequencies"},{"_id":"654f5d5f305a6842700000d9","treeId":"655a38b74450703f0b0004a4","seq":16887527,"position":2.359375,"parentId":"654fb254305a6842700000d0","content":"* capacitors, inductors, impedance, transmission lines"},{"_id":"644267499a636351720006f8","treeId":"655a38b74450703f0b0004a4","seq":16670919,"position":3.09375,"parentId":"654fb254305a6842700000d0","content":"Modulation and things, more complicated radios"},{"_id":"633268384ac6fd1762000751","treeId":"655a38b74450703f0b0004a4","seq":16887521,"position":2,"parentId":"644267499a636351720006f8","content":"Amplifiers"},{"_id":"643b8c2d620822967b00016e","treeId":"655a38b74450703f0b0004a4","seq":17487067,"position":3,"parentId":"60eab2037d14cf55a5000405","content":"## In-Class Demonstrations\n* Variac, other variac, oscilloscope, multimeter\n* Antenna analyzer"},{"_id":"63636521d532bf36e8000226","treeId":"655a38b74450703f0b0004a4","seq":17576916,"position":1,"parentId":"643b8c2d620822967b00016e","content":"[ ] IRLP\n[ ] Winlink\n[ ] SDR, VFH\n[ ] SDR, HF direct sampling\n[ ] web SDR, terrestrial\n[ ] WebSDR, satellite\n[ ] Morse code videos\n[ ] satellite contact videos\n[ ] various data network maps\n[ ] FT8\n[ ] HF SSB (club portable station)\n[ ] HF portable (person-portable)\n[ ] Ric's mobile station"},{"_id":"654fe030305a6842700000ce","treeId":"655a38b74450703f0b0004a4","seq":17487068,"position":4,"parentId":"60eab2037d14cf55a5000405","content":"## Passive Demonstrations\n* WSJT and Grid Tracker\n* Satellite contact, ISS APRS beacon\n* SDR"},{"_id":"63f33507bbcdbc7cf4000947","treeId":"655a38b74450703f0b0004a4","seq":16732127,"position":1,"parentId":"654fe030305a6842700000ce","content":"[Satellite Views](http://fiveup.io/goes/24hr.gif)\n\n[via](http://fiveup.io/goes/guide.html), [also](https://www.reddit.com/r/RTLSDR/comments/alm03j/goes17_animation_updated_every_30_minutes_with/)"},{"_id":"63748727a4889556960001e9","treeId":"655a38b74450703f0b0004a4","seq":16887094,"position":2,"parentId":"654fe030305a6842700000ce","content":"\nSatellites!\n\n[This web SDR is pointed at a geostationary communications satellite.](http://websdr.is0grb.it:8901/)\n\n* Here is a list of all [active amateur satellites](https://www.amsat.org/status/)\n\n* http://www.aprs.org/LEO-tracking.html\n\n* http://www.aprs.org/astars.html"},{"_id":"64428c649a636351720006ea","treeId":"655a38b74450703f0b0004a4","seq":17487069,"position":5,"parentId":"60eab2037d14cf55a5000405","content":"## Soldering"},{"_id":"64428c499a636351720006eb","treeId":"655a38b74450703f0b0004a4","seq":16670721,"position":1,"parentId":"64428c649a636351720006ea","content":"We need:\n* A few irons\n* Lots of flux\n* Lots of wire\n* clippers, strippers\n* Solder\n* Something to build"},{"_id":"6428cbce65aa2d1b2100017b","treeId":"655a38b74450703f0b0004a4","seq":16700287,"position":1,"parentId":"64428c499a636351720006eb","content":"[flux pen](https://www.bc-robotics.com/shop/chip-quik-no-clean-flux-pen-10ml/)"},{"_id":"654fa766305a6842700000d5","treeId":"655a38b74450703f0b0004a4","seq":17487070,"position":6,"parentId":"60eab2037d14cf55a5000405","content":"## CW (Bob? Terrace club?)"},{"_id":"64049963be41830f0500018c","treeId":"655a38b74450703f0b0004a4","seq":16719511,"position":1,"parentId":"654fa766305a6842700000d5","content":"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.\n\nhttp://www.g4fon.net/\n\nFYI, another way to acquire the equivalent of Basic with Honours is to to qualify with CW at 5 wpm. Details at:\n\nhttps://wp.rac.ca/requirements/"},{"_id":"63f2b8ffbbcdbc7cf4000948","treeId":"655a38b74450703f0b0004a4","seq":16830185,"position":2,"parentId":"654fa766305a6842700000d5","content":"[CW Skimmer software](http://www.dxatlas.com/cwskimmer/) works on Windows to reliably decode CW."},{"_id":"626b4e5bc8c25e26130002f5","treeId":"655a38b74450703f0b0004a4","seq":17104674,"position":3,"parentId":"654fa766305a6842700000d5","content":"[code practice schedule](http://www.arrl.org/w1aw-operating-schedule)"},{"_id":"5c44cf0144141078f3efde79","treeId":"655a38b74450703f0b0004a4","seq":17588914,"position":3.53125,"parentId":"655a38984450703f0b0004a6","content":"## Exam Outline, [Question Bank](https://gingkoapp.com/basic-question-bank), Study Aids\n\nThe structure of the exam is somewhat different from the structure of the course. I would argue that the exam has some serious shortcomings as a teaching tool, and is therefore not a great foundation for learning. \n\nHowever, knowing the content of the exam is essential for obtaining the license, and so it is presented comprehensively here."},{"_id":"60336e333736424504000552","treeId":"655a38b74450703f0b0004a4","seq":17681097,"position":0.125,"parentId":"5c44cf0144141078f3efde79","content":"I have created a [tree that includes all the Basic exam questions](https://gingkoapp.com/basic-question-bank). The questions are broken down by section and topic."},{"_id":"636602efd532bf36e800021c","treeId":"655a38b74450703f0b0004a4","seq":17331220,"position":0.25,"parentId":"5c44cf0144141078f3efde79","content":"The [government exam site](https://www.ic.gc.ca/eic/site/025.nsf/eng/h_00040.html) has lots of resources, including\n\n* The [entire question bank [PDF]](https://apc-cap.ic.gc.ca/datafiles/amateur_basic_questions_en.PDF) [[HTML]](https://www.ic.gc.ca/eic/site/025.nsf/eng/h_00043.html)\n* [questions by section](https://apc-cap.ic.gc.ca/pls/apc_anon/apeg_study.study_questions_intro)"},{"_id":"61c3735101c50ff7b6000b47","treeId":"655a38b74450703f0b0004a4","seq":17334327,"position":0.375,"parentId":"5c44cf0144141078f3efde79","content":"There are also more useful listings of the question bank, such as:\n* this [printed list with **explanations**](https://www.clares.ca/files/all%20questions%20rac.pdf) for each question, and\n* this [**video version** of the same thing](http://clares.ca/va6hal%20exam%20videos.html) "},{"_id":"6375a2005d0fbe476c0001cf","treeId":"655a38b74450703f0b0004a4","seq":17334974,"position":1,"parentId":"5c44cf0144141078f3efde79","content":"The exam consists of 100 questions, each on a different topic. There are, therefore, roughly 100 topics.\n\nThe Basic license exam consists of the following sections:\n\n([from RIC-3](https://www.ic.gc.ca/eic/site/smt-gst.nsf/eng/sf01008.html), [see also](https://www.ic.gc.ca/eic/site/smt-gst.nsf/eng/h_sf01709.html))"},{"_id":"5c44cf0144141078f3efde7e","treeId":"655a38b74450703f0b0004a4","seq":17225452,"position":1,"parentId":"6375a2005d0fbe476c0001cf","content":"Basic Electronics and Theory - 005 (13 questions)"},{"_id":"6492862ef3f9a390ff00062c","treeId":"655a38b74450703f0b0004a4","seq":17032080,"position":0.078125,"parentId":"5c44cf0144141078f3efde7e","content":"Basic electricity (all covered in class 2&3)"},{"_id":"64a33bcff3f9a390ff000609","treeId":"655a38b74450703f0b0004a4","seq":16624751,"position":1,"parentId":"6492862ef3f9a390ff00062c","content":"- 5-2 concepts of current, voltage, conductor, insulator, resistance"},{"_id":"64a33b9df3f9a390ff00060a","treeId":"655a38b74450703f0b0004a4","seq":16624754,"position":2,"parentId":"6492862ef3f9a390ff00062c","content":"- 5-3 concepts of energy and power, open and short circuits"},{"_id":"64a33b78f3f9a390ff00060b","treeId":"655a38b74450703f0b0004a4","seq":16624755,"position":3,"parentId":"6492862ef3f9a390ff00062c","content":"- 5-4 Ohm's law - single resistors\n- 5-5 series and parallel resistors"},{"_id":"64a34861f3f9a390ff000602","treeId":"655a38b74450703f0b0004a4","seq":16624817,"position":3.5,"parentId":"6492862ef3f9a390ff00062c","content":"- 4-6 resistor colour codes, tolerances, temperature coefficient"},{"_id":"64a339fbf3f9a390ff00060e","treeId":"655a38b74450703f0b0004a4","seq":16624756,"position":4,"parentId":"6492862ef3f9a390ff00062c","content":"- 5-6 power law, resistor power dissipation"},{"_id":"64a33a1bf3f9a390ff00060d","treeId":"655a38b74450703f0b0004a4","seq":17032078,"position":5,"parentId":"6492862ef3f9a390ff00062c","content":"- 5-7 AC, sinewave, frequency, frequency units"},{"_id":"64928542f3f9a390ff00062d","treeId":"655a38b74450703f0b0004a4","seq":17032086,"position":0.15234375,"parentId":"5c44cf0144141078f3efde7e","content":"Electromagnetism (class 4)"},{"_id":"62b74907a7ef3106690007de","treeId":"655a38b74450703f0b0004a4","seq":17032083,"position":1,"parentId":"64928542f3f9a390ff00062d","content":"- 5-9 introduction to **inductance, capacitance**\n- 5-10 introduction to **reactance, impedance**"},{"_id":"64a33c22f3f9a390ff000608","treeId":"655a38b74450703f0b0004a4","seq":17225956,"position":2,"parentId":"64928542f3f9a390ff00062d","content":"- 5-11 introduction to magnetics, transformers (Class 5)"},{"_id":"64a33c72f3f9a390ff000607","treeId":"655a38b74450703f0b0004a4","seq":17225955,"position":3,"parentId":"64928542f3f9a390ff00062d","content":"- 5-12 introduction to resonance, tuned circuits (class 5)"},{"_id":"649286f9f3f9a390ff00062a","treeId":"655a38b74450703f0b0004a4","seq":16624986,"position":2,"parentId":"5c44cf0144141078f3efde7e","content":"misc"},{"_id":"64928655f3f9a390ff00062b","treeId":"655a38b74450703f0b0004a4","seq":16624753,"position":1,"parentId":"649286f9f3f9a390ff00062a","content":"- 5-1 metric prefixes -- pico, micro, milli, centi, kilo, mega, giga"},{"_id":"64a34831f3f9a390ff000603","treeId":"655a38b74450703f0b0004a4","seq":16624982,"position":2,"parentId":"649286f9f3f9a390ff00062a","content":"- 5-13 introduction to meters and measurements"},{"_id":"64a34806f3f9a390ff000604","treeId":"655a38b74450703f0b0004a4","seq":17225453,"position":2,"parentId":"6375a2005d0fbe476c0001cf","content":"Feedlines and Antenna Systems - 006 (13 questions)"},{"_id":"64928de5f3f9a390ff000621","treeId":"655a38b74450703f0b0004a4","seq":17225536,"position":0.125,"parentId":"64a34806f3f9a390ff000604","content":"feedlines (class 5)"},{"_id":"64a33b02f3f9a390ff00060c","treeId":"655a38b74450703f0b0004a4","seq":16624801,"position":0.5,"parentId":"64928de5f3f9a390ff000621","content":"- 5-8 ratios, logarithms, decibels"},{"_id":"64928d3cf3f9a390ff000623","treeId":"655a38b74450703f0b0004a4","seq":16624712,"position":1,"parentId":"64928de5f3f9a390ff000621","content":"- 6-1 feed line characteristics, characteristic impedance\n- 6-2 balanced and unbalanced feed lines, baluns\n- 6-3 popular antenna feed line and coaxial connector types\n- 6-4 line losses by line type, length and frequency\n- 6-5 standing waves, standing wave ratio, SWR) meter\n- 6-6 concept of impedance matching"},{"_id":"64928e11f3f9a390ff000620","treeId":"655a38b74450703f0b0004a4","seq":17225542,"position":0.1875,"parentId":"64a34806f3f9a390ff000604","content":"antennas (class 5, beginning)"},{"_id":"64928d9ef3f9a390ff000622","treeId":"655a38b74450703f0b0004a4","seq":16624716,"position":0.5,"parentId":"64928e11f3f9a390ff000620","content":"- 6-7 isotropic source, polarization via element orientation"},{"_id":"64928e48f3f9a390ff00061f","treeId":"655a38b74450703f0b0004a4","seq":16624720,"position":0.75,"parentId":"64928e11f3f9a390ff000620","content":"- 6-8 wavelength vs physical length"},{"_id":"5c44cf0144141078f3efde7f","treeId":"655a38b74450703f0b0004a4","seq":16624703,"position":1,"parentId":"64928e11f3f9a390ff000620","content":"- 6-9 gain, directivity, radiation pattern, antenna bandwidth\n- 6-10 vertical antennas - types, dimensions, characteristics\n- 6-11 Yagi antennas - types, dimensions, characteristics\n- 6-12 wire antennas - types, dimensions, characteristics\n- 6-13 quad/loop antennas - types, dimensions, characteristics"},{"_id":"6492a4faf3f9a390ff000611","treeId":"655a38b74450703f0b0004a4","seq":16624721,"position":2,"parentId":"64928e11f3f9a390ff000620","content":"- 3-9 functional layout of Yagi-Uda antennas"},{"_id":"5c44cf0144141078f3efde80","treeId":"655a38b74450703f0b0004a4","seq":17225454,"position":3,"parentId":"6375a2005d0fbe476c0001cf","content":"Radio Wave Propagation - 007 (8 questions)"},{"_id":"64928b12f3f9a390ff000624","treeId":"655a38b74450703f0b0004a4","seq":16670748,"position":0.5,"parentId":"5c44cf0144141078f3efde80","content":"types of propagation &\nthe ionosphere"},{"_id":"6492899ff3f9a390ff000626","treeId":"655a38b74450703f0b0004a4","seq":16670765,"position":1,"parentId":"64928b12f3f9a390ff000624","content":"**Types of Waves**\n- 7-1 line of sight, ground wave, ionospheric wave (sky wave)\n\n**The Sun and the Ionosphere**\n- 7-5 solar activity, sunspots, sunspot cycle\n- 7-2 ionosphere, ionospheric regions (layers)\n\n**Propagation**\n- 7-3 propagation hops, skip zone, skip distance\n- 7-4 ionospheric absorption, causes and variation, fading, phase shift, Faraday rotation"},{"_id":"649287f2f3f9a390ff000629","treeId":"655a38b74450703f0b0004a4","seq":16624738,"position":0.875,"parentId":"5c44cf0144141078f3efde80","content":"practical considerations"},{"_id":"64a347adf3f9a390ff000605","treeId":"655a38b74450703f0b0004a4","seq":16624739,"position":1,"parentId":"649287f2f3f9a390ff000629","content":"- 7-6 MF and HF, critical and maximum useable frequencies, solar flux\n- 7-7 VHF and UHF, sporadic E, aurora, ducting\n- 7-8 scatter - HF, VHF, UHF"},{"_id":"5c44cf0144141078f3efde7d","treeId":"655a38b74450703f0b0004a4","seq":17225455,"position":4,"parentId":"6375a2005d0fbe476c0001cf","content":"(Active) Circuit Components - 004 (6 questions)"},{"_id":"64929012f3f9a390ff00061e","treeId":"655a38b74450703f0b0004a4","seq":16670772,"position":0.5,"parentId":"5c44cf0144141078f3efde7d","content":"- 4-1 amplifier fundamentals\n- 4-5 triode vacuum tube fundamentals\n\n\n- 4-3 bipolar transistor fundamentals\n- 4-4 field-effect transistor fundamentals\n\n- 4-2 diode fundamentals\n\n"},{"_id":"64427e409a636351720006ee","treeId":"655a38b74450703f0b0004a4","seq":16670774,"position":1,"parentId":"64929012f3f9a390ff00061e","content":"[Transistor Diode Model](https://en.wikipedia.org/wiki/Transistor_diode_model)"},{"_id":"5c44cf0144141078f3efde7c","treeId":"655a38b74450703f0b0004a4","seq":17225456,"position":5,"parentId":"6375a2005d0fbe476c0001cf","content":"Station Assembly, Practice and Safety - 003 **(21 questions)**"},{"_id":"64929683f3f9a390ff000617","treeId":"655a38b74450703f0b0004a4","seq":16624643,"position":0.03125,"parentId":"5c44cf0144141078f3efde7c","content":"modulation"},{"_id":"6492a3c8f3f9a390ff000615","treeId":"655a38b74450703f0b0004a4","seq":16670830,"position":0.25,"parentId":"64929683f3f9a390ff000617","content":"- 3-10 receiver fundamentals"},{"_id":"6492a3ecf3f9a390ff000614","treeId":"655a38b74450703f0b0004a4","seq":16670777,"position":0.5,"parentId":"64929683f3f9a390ff000617","content":"- 3-11 transmitter, carrier, keying, and amplitude modulation fundamentals"},{"_id":"6492a44df3f9a390ff000613","treeId":"655a38b74450703f0b0004a4","seq":16624644,"position":1,"parentId":"64929683f3f9a390ff000617","content":"- 3-12 carrier suppression, SSB fundamentals"},{"_id":"6492954df3f9a390ff00061a","treeId":"655a38b74450703f0b0004a4","seq":16624660,"position":3,"parentId":"64929683f3f9a390ff000617","content":"- 3-13 frequency and phase modulation fundamentals"},{"_id":"649297a2f3f9a390ff000616","treeId":"655a38b74450703f0b0004a4","seq":17331215,"position":0.125,"parentId":"5c44cf0144141078f3efde7c","content":"block diagrams\n\n[(see also block diagram study resources)](http://homepage.usask.ca/~bdb368/ham/basic/block_diagrams/index.html)"},{"_id":"64426b079a636351720006f3","treeId":"655a38b74450703f0b0004a4","seq":17331187,"position":0.1875,"parentId":"649297a2f3f9a390ff000616","content":"- 3-5 functional layout of SSB)/CW receivers"},{"_id":"64426b669a636351720006f1","treeId":"655a38b74450703f0b0004a4","seq":17331209,"position":0.328125,"parentId":"649297a2f3f9a390ff000616","content":"- 3-4 functional layout of CW transmitters"},{"_id":"6492a57ef3f9a390ff000610","treeId":"655a38b74450703f0b0004a4","seq":17331198,"position":0.46875,"parentId":"649297a2f3f9a390ff000616","content":"- 3-6 functional layout of SSB transmitters"},{"_id":"64426bbe9a636351720006ef","treeId":"655a38b74450703f0b0004a4","seq":17331204,"position":0.5390625,"parentId":"649297a2f3f9a390ff000616","content":"- 3-2 functional layout of FM transmitters"},{"_id":"64426b9f9a636351720006f0","treeId":"655a38b74450703f0b0004a4","seq":17331201,"position":0.609375,"parentId":"649297a2f3f9a390ff000616","content":"- 3-3 functional layout of FM receivers"},{"_id":"6442691d9a636351720006f4","treeId":"655a38b74450703f0b0004a4","seq":17331210,"position":2,"parentId":"649297a2f3f9a390ff000616","content":"- 3-1 functional layout of HF stations\n\npg 11-11"},{"_id":"64929408f3f9a390ff00061c","treeId":"655a38b74450703f0b0004a4","seq":17331224,"position":0.396484375,"parentId":"5c44cf0144141078f3efde7c","content":"digital stuff (also some block diagrams)"},{"_id":"649295d1f3f9a390ff000618","treeId":"655a38b74450703f0b0004a4","seq":16624669,"position":1,"parentId":"64929408f3f9a390ff00061c","content":"- 3-7 functional layout of digital systems"},{"_id":"6492a4a0f3f9a390ff000612","treeId":"655a38b74450703f0b0004a4","seq":16624670,"position":2,"parentId":"64929408f3f9a390ff00061c","content":"- 3-14 station accessories for telegraphy, radiotelephony, digital modes\n- 3-15 digital mode fundamentals RTTY, ASCII, AMTOR, packet"},{"_id":"649291b8f3f9a390ff00061d","treeId":"655a38b74450703f0b0004a4","seq":16818673,"position":0.42236328125,"parentId":"5c44cf0144141078f3efde7c","content":"power stuff"},{"_id":"64929598f3f9a390ff000619","treeId":"655a38b74450703f0b0004a4","seq":16624684,"position":1,"parentId":"649291b8f3f9a390ff00061d","content":"- 3-8 functional layout of regulated power supplies"},{"_id":"6492a737f3f9a390ff00060f","treeId":"655a38b74450703f0b0004a4","seq":16624685,"position":2,"parentId":"649291b8f3f9a390ff00061d","content":"- 3-16 cells and batteries, types, ratings, charging\n- 3-17 power supply fundamentals"},{"_id":"649294bef3f9a390ff00061b","treeId":"655a38b74450703f0b0004a4","seq":16624661,"position":0.75,"parentId":"5c44cf0144141078f3efde7c","content":"safety"},{"_id":"64a34899f3f9a390ff000601","treeId":"655a38b74450703f0b0004a4","seq":16624662,"position":1,"parentId":"649294bef3f9a390ff00061b","content":"- 3-18 electrical hazards, electrical safety, security\n- 3-19 electrical safety ground, capacitor discharge, fuse replacement\n- 3-20 antenna and tower safety, lightning protection\n- 3-21 exposure of human body to RF, safety precautions"},{"_id":"5c44cf0144141078f3efde81","treeId":"655a38b74450703f0b0004a4","seq":17225462,"position":6,"parentId":"6375a2005d0fbe476c0001cf","content":"Interference and Suppression - 008 (5 questions)"},{"_id":"64a3477df3f9a390ff000606","treeId":"655a38b74450703f0b0004a4","seq":16613618,"position":1,"parentId":"5c44cf0144141078f3efde81","content":"- 8-1 front-end overload, cross-modulation\n- 8-2 audio rectification, bypass capacitors, ferrites\n- 8-3 intermodulation, spurious, key-clicks\n- 8-4 harmonics, splatter, transmitter adjustments\n- 8-5 use of filters: low-pass, high-pass, band-pass, band-reject"},{"_id":"5c44cf0144141078f3efde7a","treeId":"655a38b74450703f0b0004a4","seq":17225463,"position":7,"parentId":"6375a2005d0fbe476c0001cf","content":"Regulations and Policies - 001 **(25 Questions)**"},{"_id":"64926e0ef3f9a390ff00062e","treeId":"655a38b74450703f0b0004a4","seq":16624819,"position":0.5,"parentId":"5c44cf0144141078f3efde7a","content":"licenses"},{"_id":"64926d50f3f9a390ff00062f","treeId":"655a38b74450703f0b0004a4","seq":16624832,"position":1,"parentId":"64926e0ef3f9a390ff00062e","content":"- 1-1 radio licences, applicability, eligibility of licence holder\n- 1-2 licence fee, term, posting requirements, change of address\n- 1-3 licence suspension or revocation, powers of radio inspectors, offences and punishments\n- 1-4 operator certificates, applicability, eligibility, equivalents, reciprocal recognition"},{"_id":"64926766f3f9a390ff00063c","treeId":"655a38b74450703f0b0004a4","seq":16624864,"position":2,"parentId":"64926e0ef3f9a390ff00062e","content":"- 1-22 examinations - Department's fees, delegated examinations, fees, disabled accommodation"},{"_id":"64925f48f3f9a390ff000643","treeId":"655a38b74450703f0b0004a4","seq":16624902,"position":0.505859375,"parentId":"5c44cf0144141078f3efde7a","content":"nature of amateur communications"},{"_id":"64926916f3f9a390ff000636","treeId":"655a38b74450703f0b0004a4","seq":16624909,"position":1,"parentId":"64925f48f3f9a390ff000643","content":"- 1-7 content restrictions - non-superfluous, profanity, secret code, music, non-commercial"},{"_id":"649263a0f3f9a390ff000640","treeId":"655a38b74450703f0b0004a4","seq":16624913,"position":2,"parentId":"64925f48f3f9a390ff000643","content":"- 1-13 station identification, call signs, prefixes"},{"_id":"64926cc7f3f9a390ff000630","treeId":"655a38b74450703f0b0004a4","seq":16624918,"position":3,"parentId":"64925f48f3f9a390ff000643","content":"- 1-12 non-remuneration, privacy of communications"},{"_id":"64926b46f3f9a390ff000633","treeId":"655a38b74450703f0b0004a4","seq":16818689,"position":0.6634521484375,"parentId":"5c44cf0144141078f3efde7a","content":"**Operating Privileges**\nBasically, the topics pertaining to operating privileges boil down to:\n* bands\n* bandwidth\n* power\n* clean signals"},{"_id":"64926b5af3f9a390ff000632","treeId":"655a38b74450703f0b0004a4","seq":16624830,"position":1,"parentId":"64926b46f3f9a390ff000633","content":"- 1-15 frequency bands and qualification requirements\n- 1-16 maximum bandwidth by frequency bands\n- 1-17 restrictions on capacity and power output by qualifications\n- 1-18 unmodulated carriers, retransmission\n- 1-19 amplitude modulation, frequency stability, measurements"},{"_id":"64925d7ef3f9a390ff000644","treeId":"655a38b74450703f0b0004a4","seq":16624972,"position":0.74188232421875,"parentId":"5c44cf0144141078f3efde7a","content":"legal operation"},{"_id":"649268d3f3f9a390ff000637","treeId":"655a38b74450703f0b0004a4","seq":16624960,"position":0.125,"parentId":"64925d7ef3f9a390ff000644","content":"- 1-6 operation of radio apparatus, terms of licence, applicable standards, exempt apparatus"},{"_id":"649268b6f3f9a390ff000638","treeId":"655a38b74450703f0b0004a4","seq":16624957,"position":0.25,"parentId":"64925d7ef3f9a390ff000644","content":"- 1-5 operation, repair and maintenance of radio apparatus on behalf of other persons"},{"_id":"64926929f3f9a390ff000635","treeId":"655a38b74450703f0b0004a4","seq":16624976,"position":0.5,"parentId":"64925d7ef3f9a390ff000644","content":"- 1-8 installation and operating restrictions - number of stations, repeaters, home-built, club stations"},{"_id":"64926988f3f9a390ff000634","treeId":"655a38b74450703f0b0004a4","seq":16624955,"position":0.75,"parentId":"64925d7ef3f9a390ff000644","content":"- 1-9 participation in communications by visitors, use of station by others"},{"_id":"64925cdff3f9a390ff000645","treeId":"655a38b74450703f0b0004a4","seq":16624925,"position":0.8203125,"parentId":"5c44cf0144141078f3efde7a","content":"playing nice with others"},{"_id":"6492637af3f9a390ff000641","treeId":"655a38b74450703f0b0004a4","seq":16624929,"position":2,"parentId":"64925cdff3f9a390ff000645","content":"- 1-11 emergency communications (real or simulated), communication with non-amateur stations"},{"_id":"64926435f3f9a390ff00063e","treeId":"655a38b74450703f0b0004a4","seq":16624935,"position":3,"parentId":"64925cdff3f9a390ff000645","content":"- 1-23 antenna structure approval, neighbour and land-use authority consultation"},{"_id":"649267faf3f9a390ff00063a","treeId":"655a38b74450703f0b0004a4","seq":16624940,"position":4,"parentId":"64925cdff3f9a390ff000645","content":"- 1-24 radio frequency electromagnetic field limits"},{"_id":"64926095f3f9a390ff000642","treeId":"655a38b74450703f0b0004a4","seq":16624970,"position":0.980224609375,"parentId":"5c44cf0144141078f3efde7a","content":"international stuff"},{"_id":"64926c65f3f9a390ff000631","treeId":"655a38b74450703f0b0004a4","seq":16624946,"position":0.5,"parentId":"64926095f3f9a390ff000642","content":"- 1-14 foreign amateur operation in Canada, banned countries, third-party messages"},{"_id":"64926408f3f9a390ff00063f","treeId":"655a38b74450703f0b0004a4","seq":16624878,"position":1,"parentId":"64926095f3f9a390ff000642","content":"- 1-20 International Telecommunication Union (ITU) Radio Regulations, applicability"},{"_id":"64926795f3f9a390ff00063b","treeId":"655a38b74450703f0b0004a4","seq":16624881,"position":2,"parentId":"64926095f3f9a390ff000642","content":"- 1-21 operation outside Canada, ITU regions, reciprocal privileges, international licences"},{"_id":"649264a6f3f9a390ff00063d","treeId":"655a38b74450703f0b0004a4","seq":16624865,"position":0.98828125,"parentId":"5c44cf0144141078f3efde7a","content":"interference"},{"_id":"64926835f3f9a390ff000639","treeId":"655a38b74450703f0b0004a4","seq":16624941,"position":0.5,"parentId":"649264a6f3f9a390ff00063d","content":"- 1-10 interference, determination, protection from interference"},{"_id":"64a34911f3f9a390ff0005ff","treeId":"655a38b74450703f0b0004a4","seq":16624866,"position":1,"parentId":"649264a6f3f9a390ff00063d","content":"- 1-25 criteria for resolution of radio frequency interference complaints"},{"_id":"5c44cf0144141078f3efde7b","treeId":"655a38b74450703f0b0004a4","seq":17225464,"position":8,"parentId":"6375a2005d0fbe476c0001cf","content":"Operating and Procedures - 002 (9 questions)"},{"_id":"64a348d7f3f9a390ff000600","treeId":"655a38b74450703f0b0004a4","seq":16613600,"position":1,"parentId":"5c44cf0144141078f3efde7b","content":"- 2-1 voice operating procedures - channelized VHF/UHF repeater\n- 2-2 phonetic alphabet\n- 2-3 voice operating procedures - simplex VHF/UHF and HF\n- 2-4 tuneups and testing, use of dummy load, courteous operation\n- 2-5 Morse (CW) operating procedures, procedural signs\n- 2-6 RST system of signal reporting, use of S meter\n- 2-7 Q signals\n- 2-8 emergency operating procedures\n- 2-9 record keeping, confirmation practices, maps/charts, antenna orientation"},{"_id":"61a8112392741f38d30003a5","treeId":"655a38b74450703f0b0004a4","seq":17588915,"position":3,"parentId":"5c44cf0144141078f3efde79","content":"See also a complete course, broken down by topic [from Yukon amateur radio society](http://www.ykars.com/index.php/en/basic-qualification-course.html), with links to internet rsources, and chapter references to the Coax study guide."},{"_id":"61a7ffd592741f38d30003a6","treeId":"655a38b74450703f0b0004a4","seq":17588917,"position":4,"parentId":"5c44cf0144141078f3efde79","content":"For a different treatment, the Delta Amateur Radio club also has [a similar page of resources](https://deltaamateurradio.com/wp/?page_id=1160)."},{"_id":"654f72bd305a6842700000d6","treeId":"655a38b74450703f0b0004a4","seq":18929587,"position":4.796875,"parentId":"655a38984450703f0b0004a6","content":"## Scheduling & Administrivia"},{"_id":"5968b01f25a0d6265a000423","treeId":"655a38b74450703f0b0004a4","seq":18929591,"position":0.25,"parentId":"654f72bd305a6842700000d6","content":"## Scheduling & Fees"},{"_id":"5968ae8625a0d6265a000424","treeId":"655a38b74450703f0b0004a4","seq":18929595,"position":0.375,"parentId":"654f72bd305a6842700000d6","content":"Introductory sessions are provided free. Course fee is $60, with all materials provided including textbook. Also includes exam and BVARS membership."},{"_id":"654f6efd305a6842700000d8","treeId":"655a38b74450703f0b0004a4","seq":16895261,"position":2,"parentId":"654f72bd305a6842700000d6","content":"Classes are held weekly on Monday evening at Ranger Park building in Smithers. Expected duration eight weeks. Schedule determined in consultation with students."},{"_id":"654f7275305a6842700000d7","treeId":"655a38b74450703f0b0004a4","seq":18929592,"position":2.5,"parentId":"654f72bd305a6842700000d6","content":"Two introductory sessions: February 26 7-9 PM, and Saturday March 2 12-2 PM."},{"_id":"60794e53aebbb6f1d7000408","treeId":"655a38b74450703f0b0004a4","seq":18929582,"position":3,"parentId":"654f72bd305a6842700000d6","content":"##Textbooks\n\nThere are two priominent licensing textbooks in Canada:\n* [Hamstudy](https://www.hamstudy.com/)\n* [Coax Publications Study Guide](https://www.coaxpublications.ca/ord0001.php)"},{"_id":"654f4a53305a6842700000e1","treeId":"655a38b74450703f0b0004a4","seq":18929599,"position":1,"parentId":"60794e53aebbb6f1d7000408","content":"Textbooks available to loan, or purchase for $20."},{"_id":"654f5ae4305a6842700000db","treeId":"655a38b74450703f0b0004a4","seq":18929584,"position":4,"parentId":"654f72bd305a6842700000d6","content":"## Course Promotion"},{"_id":"654f5abd305a6842700000dc","treeId":"655a38b74450703f0b0004a4","seq":16830503,"position":1,"parentId":"654f5ae4305a6842700000db","content":"[X] Facebook"},{"_id":"654f0b03305a6842700000e4","treeId":"655a38b74450703f0b0004a4","seq":16495737,"position":1,"parentId":"654f5abd305a6842700000dc","content":"create a group"},{"_id":"654f5aa9305a6842700000dd","treeId":"655a38b74450703f0b0004a4","seq":16830508,"position":2,"parentId":"654f5ae4305a6842700000db","content":"Posters\n[X] Public Library\n[X] Dze L K'ant Friendship Center"},{"_id":"5d42a30ae816e6298f000967","treeId":"655a38b74450703f0b0004a4","seq":18341345,"position":3,"parentId":"654f5aa9305a6842700000dd","content":"List of bulletin boards\n* Petro Can (south exterior wall)\n* Two Sisters (inside, bathrooms)\n* Town hall (inside)\n* No Frills (inside)\n* Central Park building (outside)\n* Mtn Eagle Books (outside)\n* Public Library (inside)"},{"_id":"64f2ffec47e9c1390e000153","treeId":"655a38b74450703f0b0004a4","seq":16640131,"position":2.5,"parentId":"654f5ae4305a6842700000db","content":"[X] Smithers Events (bugwood screen)\nhttp://smithersevents.com/\n\nhttp://calendarnorth.com/communities/smithers\nhttp://calendarnorth.com/form/"},{"_id":"636834d553b88b9b460003a0","treeId":"655a38b74450703f0b0004a4","seq":16830501,"position":2.5625,"parentId":"654f5ae4305a6842700000db","content":"Community Radio Station\n[X] CICK Facebook\n\n[X] Porch Talk"},{"_id":"6412186ca0ff8a5e60000288","treeId":"655a38b74450703f0b0004a4","seq":16830488,"position":1.00001,"parentId":"636834d553b88b9b460003a0","content":"[ISS Video](https://youtu.be/h73EYcyszf8?t=679)"},{"_id":"64120bc2a0ff8a5e6000028a","treeId":"655a38b74450703f0b0004a4","seq":16830489,"position":1.50001,"parentId":"636834d553b88b9b460003a0","content":"[20 m DX](https://youtu.be/NbO4M9kVDPU?t=33)"},{"_id":"6411f5a3a0ff8a5e6000028d","treeId":"655a38b74450703f0b0004a4","seq":16830490,"position":1.62501,"parentId":"636834d553b88b9b460003a0","content":"[ragchew](https://youtu.be/BlaRsgpokAI?t=774)"},{"_id":"6411fde0a0ff8a5e6000028b","treeId":"655a38b74450703f0b0004a4","seq":16830491,"position":1.75001,"parentId":"636834d553b88b9b460003a0","content":"[moonbounce](https://youtu.be/VEHqcs8GZvM?t=11)"},{"_id":"6411fb98a0ff8a5e6000028c","treeId":"655a38b74450703f0b0004a4","seq":16830492,"position":1.87501,"parentId":"636834d553b88b9b460003a0","content":"music: [radar rider](https://www.youtube.com/watch?v=9OhO-uikL1s)"},{"_id":"64121581a0ff8a5e60000289","treeId":"655a38b74450703f0b0004a4","seq":16830493,"position":2.00001,"parentId":"636834d553b88b9b460003a0","content":"[conversation stack](https://www.youtube.com/watch?v=L4Fl4EVkxEk) (interesting, but not for now)"},{"_id":"64f2ff1047e9c1390e000154","treeId":"655a38b74450703f0b0004a4","seq":16830502,"position":2.75,"parentId":"654f5ae4305a6842700000db","content":"Mailing LIsts\n[ ] In the loop, others?\n[X] BVARS Club list\n[ ] Last course list"},{"_id":"654f47ed305a6842700000e2","treeId":"655a38b74450703f0b0004a4","seq":18929586,"position":5,"parentId":"654f72bd305a6842700000d6","content":"## Funding"},{"_id":"60795368aebbb6f1d7000407","treeId":"655a38b74450703f0b0004a4","seq":18927098,"position":1,"parentId":"654f47ed305a6842700000e2","content":"Education and training are eligible for funding by Community Gaming Grants."},{"_id":"654f409a305a6842700000e3","treeId":"655a38b74450703f0b0004a4","seq":18929588,"position":5.3984375,"parentId":"655a38984450703f0b0004a6","content":"## Misc Resources\n(to be organized later)"},{"_id":"6375824b5d0fbe476c0001d5","treeId":"655a38b74450703f0b0004a4","seq":18929616,"position":4.76837158203125e-7,"parentId":"654f409a305a6842700000e3","content":"There is a [list of web SDRs](http://www.websdr.org/) that you can use to listen to the HF bands online. There is [one in the netherlands](http://websdr.ewi.utwente.nl:8901/) that is rather good. Here is [a map](https://sdr.hu/map). Here is [a different kind of map](http://ve3sun.com/KiwiSDR/). Here is [another credible list](https://skywavelinux.com/best-sdrservers.html)."},{"_id":"592426f7767be9ecdc000426","treeId":"655a38b74450703f0b0004a4","seq":18958090,"position":1,"parentId":"6375824b5d0fbe476c0001d5","content":"[for example](http://www.sdrutah.org/websdr3.html)"},{"_id":"5cdc3edc3e80f853e00005d9","treeId":"655a38b74450703f0b0004a4","seq":18117445,"position":9.5367431640625e-7,"parentId":"654f409a305a6842700000e3","content":"vacuum tube reciever\n\nhttps://blog.tindie.com/2019/07/vacuum-tube-radio-kit/\n\nhttps://www.tindie.com/products/microwavemont/breadboard-vacuum-tube-radio-kit/"},{"_id":"6034284d3bce8506f300040d","treeId":"655a38b74450703f0b0004a4","seq":17585537,"position":0.0000019073486328125,"parentId":"654f409a305a6842700000e3","content":"video: [use a scope to match an antenna and measure impedance](https://www.youtube.com/watch?v=eYN7dhdt1Dw)"},{"_id":"60efb26461de4adcbe000828","treeId":"655a38b74450703f0b0004a4","seq":17485109,"position":0.000003814697265625,"parentId":"654f409a305a6842700000e3","content":"\n* [available call signs](https://apc-cap.ic.gc.ca/pls/apc_anon/query_avail_cs$.startup)\n"},{"_id":"61404d6ca0996a554d0003e5","treeId":"655a38b74450703f0b0004a4","seq":17425395,"position":0.00000762939453125,"parentId":"654f409a305a6842700000e3","content":"kjs crystal radio, big litz\nhttp://www.lessmiths.com/~kjsmith/crystal/blitz.shtml\n\nA Good Crystal Radio Design With Some Justification\nhttp://www.interestingelectronics.com/old/henrys_interesting_electronics/loud_crystal_set_radio/loud_crystal_set_radio.htm\n\nA Good Crystal Radio Design With Some Justification\nhttp://www.interestingelectronics.com/old/henrys_interesting_electronics/crystal_radio_v2/crystal_set_radio_v2.htm\n\n"},{"_id":"61a23c0c14cd24a9700003d9","treeId":"655a38b74450703f0b0004a4","seq":17338085,"position":0.0000152587890625,"parentId":"654f409a305a6842700000e3","content":"pretty good notes on a bunch of topics\nhttp://spiff.rit.edu/classes/phys213/lectures/"},{"_id":"61a2598614cd24a9700003d6","treeId":"655a38b74450703f0b0004a4","seq":17337886,"position":0.000030517578125,"parentId":"654f409a305a6842700000e3","content":"To be deployed when I need to hand-wave something away: You can tell something is a tautology [because of the way it is](https://youtu.be/Hm3JodBR-vs?t=67)"},{"_id":"61a2c51214cd24a9700003bf","treeId":"655a38b74450703f0b0004a4","seq":17336714,"position":0.00006103515625,"parentId":"654f409a305a6842700000e3","content":"If somebody buys me [one of these](https://www.abebooks.com/servlet/SearchResults?cm_sp=SearchFwi-_-SRP-_-Results&kn=1924&sortby=17&tn=radio%20handbook) I will be happy. My copy is missing a few key pages."},{"_id":"62b6d339a7ef3106690007f4","treeId":"655a38b74450703f0b0004a4","seq":17032527,"position":0.0001220703125,"parentId":"654f409a305a6842700000e3","content":"[playlist of electronics training videos](https://www.youtube.com/playlist?list=PLvplkb-chocV8788-jlgxKyTItOtyQTTE)"},{"_id":"62f200b9a1a2897b6800034e","treeId":"655a38b74450703f0b0004a4","seq":16971183,"position":0.000244140625,"parentId":"654f409a305a6842700000e3","content":"[darth vector's youtube channel](https://www.youtube.com/channel/UCO4ofPu2EvoXOKDWimHLUTw)"},{"_id":"6318156bd1bfa6b5a2000790","treeId":"655a38b74450703f0b0004a4","seq":16915726,"position":0.000732421875,"parentId":"654f409a305a6842700000e3","content":"[imaginary numbers](https://www.youtube.com/watch?v=T647CGsuOVU&t=107s)"},{"_id":"63755de25d0fbe476c0001d6","treeId":"655a38b74450703f0b0004a4","seq":18929604,"position":0.0009765625,"parentId":"654f409a305a6842700000e3","content":"### **Let's talk about radios.**\nThe following is the beginning of a history lesson that will continue throughout the course."},{"_id":"642806bc65aa2d1b2100017d","treeId":"655a38b74450703f0b0004a4","seq":16821386,"position":1,"parentId":"63755de25d0fbe476c0001d6","content":"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."},{"_id":"6374df85a4889556960001d9","treeId":"655a38b74450703f0b0004a4","seq":16821387,"position":2,"parentId":"642806bc65aa2d1b2100017d","content":"Here is a [chart of technology adoption](\nhttps://cms.qz.com/wp-content/uploads/2014/03/consumption-spreads-faster-today-nyt.jpg?quality=75&strip=all&w=1260), which helps to explain why radios are what they are today. Here is [a different kind of chart](https://www.google.com/search?q=gartner+hype+cycle&source=lnms&tbm=isch), which speaks to some of the same things."},{"_id":"6421a95265aa2d1b21000180","treeId":"655a38b74450703f0b0004a4","seq":16821388,"position":3,"parentId":"642806bc65aa2d1b2100017d","content":"(I got the chart from an interesting [article on the microwave oven](https://qz.com/187743/the-slow-death-of-the-microwave/).)"},{"_id":"63749e4ba4889556960001dc","treeId":"655a38b74450703f0b0004a4","seq":16821732,"position":1.5,"parentId":"63755de25d0fbe476c0001d6","content":"Radios are powerful."},{"_id":"63749e1aa4889556960001dd","treeId":"655a38b74450703f0b0004a4","seq":16821746,"position":1,"parentId":"63749e4ba4889556960001dc","content":"For example, the [Nazis loved radio](https://en.wikipedia.org/wiki/Volksempf%C3%A4nger)."},{"_id":"63755ceb5d0fbe476c0001d8","treeId":"655a38b74450703f0b0004a4","seq":16895272,"position":2,"parentId":"63749e4ba4889556960001dc","content":"For the community radio station CICK in the train car, the [orientation manual](http://www.smithersradio.com/files/Working%20Copy%20of%20Orientation%20Manual.docx.pdf) 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.\")"},{"_id":"6371ddb653b88b9b4600036e","treeId":"655a38b74450703f0b0004a4","seq":16824218,"position":2.5,"parentId":"63749e4ba4889556960001dc","content":"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. "},{"_id":"637120fa53b88b9b4600037c","treeId":"655a38b74450703f0b0004a4","seq":16830141,"position":4,"parentId":"63755de25d0fbe476c0001d6","content":"What follows is a not-so-brief digression into amateur radio history:"},{"_id":"6371d89d53b88b9b4600036f","treeId":"655a38b74450703f0b0004a4","seq":16824372,"position":1,"parentId":"637120fa53b88b9b4600037c","content":"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."},{"_id":"637100d953b88b9b46000384","treeId":"655a38b74450703f0b0004a4","seq":16824417,"position":1,"parentId":"6371d89d53b88b9b4600036f","content":"(For a technical explanation, [this wikipedia article](https://en.wikipedia.org/wiki/Damped_wave) is a start.)"},{"_id":"6371846d53b88b9b46000373","treeId":"655a38b74450703f0b0004a4","seq":16824373,"position":2,"parentId":"637120fa53b88b9b4600037c","content":"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."},{"_id":"637185fa53b88b9b46000372","treeId":"655a38b74450703f0b0004a4","seq":16824374,"position":3,"parentId":"637120fa53b88b9b4600037c","content":"US govt passed the Radio act of 1912 in response to the [confusion that was involved in the sinking of the Titanic](https://www.rfvenue.com/blog/2014/12/13/how-wireless-interference-helped-sink-the-titanic). There was also the international ratdiotelegraph conference of 1912."},{"_id":"6371458d53b88b9b46000377","treeId":"655a38b74450703f0b0004a4","seq":16824356,"position":0.5,"parentId":"637185fa53b88b9b46000372","content":"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."},{"_id":"6371722a53b88b9b46000374","treeId":"655a38b74450703f0b0004a4","seq":16824338,"position":1,"parentId":"637185fa53b88b9b46000372","content":"[Full text of the act](http://earlyradiohistory.us/1912act.htm)"},{"_id":"63716fbb53b88b9b46000375","treeId":"655a38b74450703f0b0004a4","seq":16824355,"position":2,"parentId":"637185fa53b88b9b46000372","content":"There is a very long presentation that contains more than you would ever want to know about [radios on the titanic](http://www.halifax-arc.org/pdf/TitanicRadio1.pdf)"},{"_id":"6371335753b88b9b46000378","treeId":"655a38b74450703f0b0004a4","seq":16824375,"position":4,"parentId":"637120fa53b88b9b4600037c","content":"Amateurs were restricted to wavelengths less than 200 m, which at the time were thought to be useless."},{"_id":"6371311853b88b9b46000379","treeId":"655a38b74450703f0b0004a4","seq":16824361,"position":1,"parentId":"6371335753b88b9b46000378","content":"Reference: https://www.electronics-notes.com/articles/history/amateur-ham-radio/ham-licenses-introduced.php"},{"_id":"6371c7dc53b88b9b46000370","treeId":"655a38b74450703f0b0004a4","seq":16824423,"position":5,"parentId":"637120fa53b88b9b4600037c","content":"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."},{"_id":"63712c3553b88b9b4600037a","treeId":"655a38b74450703f0b0004a4","seq":16824368,"position":1,"parentId":"6371c7dc53b88b9b46000370","content":"[In Britain, the fear was that amateur radios could be used for spying.](https://www.electronics-notes.com/articles/history/amateur-ham-radio/ham-radio-operations-first-world-war.php)"},{"_id":"6371272a53b88b9b4600037b","treeId":"655a38b74450703f0b0004a4","seq":16824377,"position":6,"parentId":"637120fa53b88b9b4600037c","content":"Amateur operators advocated that politicians direct the US navy to relinquish control..."},{"_id":"6371198e53b88b9b4600037d","treeId":"655a38b74450703f0b0004a4","seq":16824386,"position":6.5,"parentId":"637120fa53b88b9b4600037c","content":"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.)"},{"_id":"6371017753b88b9b46000383","treeId":"655a38b74450703f0b0004a4","seq":16824416,"position":1,"parentId":"6371198e53b88b9b4600037d","content":"https://www.electronics-notes.com/articles/history/amateur-ham-radio/first-transatlantic-contacts.php"},{"_id":"637110c253b88b9b4600037f","treeId":"655a38b74450703f0b0004a4","seq":16824391,"position":6.75,"parentId":"637120fa53b88b9b4600037c","content":"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.)"},{"_id":"63710e0553b88b9b46000380","treeId":"655a38b74450703f0b0004a4","seq":16824392,"position":6.875,"parentId":"637120fa53b88b9b4600037c","content":"Then the roaring twenties happen..."},{"_id":"63710db953b88b9b46000381","treeId":"655a38b74450703f0b0004a4","seq":16833413,"position":6.9375,"parentId":"637120fa53b88b9b4600037c","content":"And then the depressing thirties... Nobody's got any money, so the people who are experimenting with radio are, well, well-off."},{"_id":"63710c4353b88b9b46000382","treeId":"655a38b74450703f0b0004a4","seq":16824400,"position":1,"parentId":"63710db953b88b9b46000381","content":"Just take a look at the pictures and prices this old handbook."},{"_id":"6370fd9e53b88b9b46000385","treeId":"655a38b74450703f0b0004a4","seq":16824424,"position":6.96875,"parentId":"637120fa53b88b9b4600037c","content":"FM invented and used by amateur radio experimenters at this time."},{"_id":"637159f553b88b9b46000376","treeId":"655a38b74450703f0b0004a4","seq":16824638,"position":8,"parentId":"637120fa53b88b9b4600037c","content":"In USA, foreign communication banned 1940. All operation [banned again during the second world war](https://commons.wikimedia.org/wiki/File:FCC_WW2.jpg)."},{"_id":"6370ee6253b88b9b46000389","treeId":"655a38b74450703f0b0004a4","seq":16824449,"position":1,"parentId":"637159f553b88b9b46000376","content":"[More on the ban.](https://www.quora.com/What-was-the-global-state-of-ham-radio-during-World-War-II)"},{"_id":"6370fce253b88b9b46000386","treeId":"655a38b74450703f0b0004a4","seq":16824425,"position":8.5,"parentId":"637120fa53b88b9b4600037c","content":"FM used extensively in the war."},{"_id":"6370fc8853b88b9b46000387","treeId":"655a38b74450703f0b0004a4","seq":16824427,"position":8.75,"parentId":"637120fa53b88b9b4600037c","content":"Single sideband invented in the fifties, allowing more efficient use of spectrum and power."},{"_id":"6370825153b88b9b4600038a","treeId":"655a38b74450703f0b0004a4","seq":16824778,"position":8.8125,"parentId":"637120fa53b88b9b4600037c","content":"Canadian Amateur Radio Federation founded in 1967. Precursior to RAC."},{"_id":"637079ae53b88b9b4600038b","treeId":"655a38b74450703f0b0004a4","seq":16824781,"position":1,"parentId":"6370825153b88b9b4600038a","content":"[CRRL/CARF/RAC history](https://ve3we.org/2017/04/25/history-of-amateur-radio-in-canada/)"},{"_id":"6370f19453b88b9b46000388","treeId":"655a38b74450703f0b0004a4","seq":16824435,"position":8.875,"parentId":"637120fa53b88b9b4600037c","content":"And so on."},{"_id":"63749b52a4889556960001de","treeId":"655a38b74450703f0b0004a4","seq":16895269,"position":4.5,"parentId":"63755de25d0fbe476c0001d6","content":"There are some radios that you use to listen, and some radios that you use to talk."},{"_id":"63749adea4889556960001df","treeId":"655a38b74450703f0b0004a4","seq":16821822,"position":1,"parentId":"63749b52a4889556960001de","content":"The radios that you use to listen are, effectievly, unregulated."},{"_id":"63749a43a4889556960001e0","treeId":"655a38b74450703f0b0004a4","seq":16821823,"position":2,"parentId":"63749b52a4889556960001de","content":"The radios that you use to talk are tightly regulated."},{"_id":"6374997ea4889556960001e1","treeId":"655a38b74450703f0b0004a4","seq":16821825,"position":3,"parentId":"63749b52a4889556960001de","content":"The radios that anybody can talk on, are, frankly, kind of lame."},{"_id":"6374979fa4889556960001e3","treeId":"655a38b74450703f0b0004a4","seq":16830149,"position":1,"parentId":"6374997ea4889556960001e1","content":"I'm talking about walkie talkies, FRS radios, CB radio. Also cell phones, WiFi.\n\nThey are made to do only one thing, and you can't adjust them.\n\n(At least you're allowed to use encryption over WiFi...)"},{"_id":"63749923a4889556960001e2","treeId":"655a38b74450703f0b0004a4","seq":16821828,"position":4,"parentId":"63749b52a4889556960001de","content":"The radios that are more exclusive are more versatile."},{"_id":"63686f2353b88b9b46000394","treeId":"655a38b74450703f0b0004a4","seq":16830150,"position":1,"parentId":"63749923a4889556960001e2","content":"bush radios, marine radios, radars, amateur radars..."},{"_id":"637111bf53b88b9b4600037e","treeId":"655a38b74450703f0b0004a4","seq":16824387,"position":5,"parentId":"63749b52a4889556960001de","content":"How versatile? Well."},{"_id":"6374958ca4889556960001e4","treeId":"655a38b74450703f0b0004a4","seq":16830154,"position":5,"parentId":"63755de25d0fbe476c0001d6","content":"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.\n\nThe way this continues today is that you're not allowed to obscure who you are, and what you're saying.","deleted":false},{"_id":"639068853f36d7980400027b","treeId":"655a38b74450703f0b0004a4","seq":16799364,"position":0.001953125,"parentId":"654f409a305a6842700000e3","content":"[A list of contests](https://www.contestcalendar.com/weeklycont.php) ongoing at any time"},{"_id":"64ba2ee8ebc10cea1f000100","treeId":"655a38b74450703f0b0004a4","seq":16601427,"position":0.015625,"parentId":"654f409a305a6842700000e3","content":"http://www.angelfire.com/electronic/funwithtubes/Breadboarding.html"},{"_id":"64ba2f14ebc10cea1f0000ff","treeId":"655a38b74450703f0b0004a4","seq":16601426,"position":0.03125,"parentId":"654f409a305a6842700000e3","content":"http://www.sdmakersguild.org/the-art-of-manhattan-style-circuit-construction/"},{"_id":"64ba2f68ebc10cea1f0000fe","treeId":"655a38b74450703f0b0004a4","seq":16601425,"position":0.0625,"parentId":"654f409a305a6842700000e3","content":"https://www.tubesandmore.com/products/fahnestock-clip-package-6"},{"_id":"64ba2f92ebc10cea1f0000fd","treeId":"655a38b74450703f0b0004a4","seq":16601424,"position":0.125,"parentId":"654f409a305a6842700000e3","content":"http://www.analogdial.com/MorganAmp/MorganAmp2.htm"},{"_id":"64ba2fd6ebc10cea1f0000fc","treeId":"655a38b74450703f0b0004a4","seq":16601423,"position":0.25,"parentId":"654f409a305a6842700000e3","content":"http://www.analogdial.com/CrystalSet/CrystalRadio4.html"},{"_id":"653f67f0167ad2eb3c000165","treeId":"655a38b74450703f0b0004a4","seq":16509733,"position":0.5,"parentId":"654f409a305a6842700000e3","content":"[modular transceiver](https://www.minikits.com.au/m1-transceiver.htm)"},{"_id":"654bccb0305a6842700000e5","treeId":"655a38b74450703f0b0004a4","seq":16497926,"position":1,"parentId":"654f409a305a6842700000e3","content":"[qrp labs](https://www.qrp-labs.com/)"},{"_id":"5cacc4f8707a84036a246228","treeId":"655a38b74450703f0b0004a4","seq":18929607,"position":1.25,"parentId":"654f409a305a6842700000e3","content":"Crystal radio design"},{"_id":"5cacc4f8707a84036a246229","treeId":"655a38b74450703f0b0004a4","seq":17425389,"position":1,"parentId":"5cacc4f8707a84036a246228","content":"kjs crystal radio, big litz\nhttp://www.lessmiths.com/~kjsmith/crystal/blitz.shtml"},{"_id":"5cacc4f8707a84036a24622a","treeId":"655a38b74450703f0b0004a4","seq":17425390,"position":2,"parentId":"5cacc4f8707a84036a246228","content":"A Good Crystal Radio Design With Some Justification\nhttp://www.interestingelectronics.com/old/henrys_interesting_electronics/loud_crystal_set_radio/loud_crystal_set_radio.htm"},{"_id":"5cacc4f8707a84036a24622b","treeId":"655a38b74450703f0b0004a4","seq":17425391,"position":3,"parentId":"5cacc4f8707a84036a246228","content":"A Good Crystal Radio Design With Some Justification\nhttp://www.interestingelectronics.com/old/henrys_interesting_electronics/crystal_radio_v2/crystal_set_radio_v2.htm"},{"_id":"653e1716167ad2eb3c000213","treeId":"655a38b74450703f0b0004a4","seq":16510904,"position":1.5,"parentId":"654f409a305a6842700000e3","content":"http://circuit-zone.com/?cat=fm_transmitters\n\nhttp://electronics-diy.com/super-simple-ipod-fm-transmitter.php"},{"_id":"654bc918305a6842700000e6","treeId":"655a38b74450703f0b0004a4","seq":16497930,"position":2,"parentId":"654f409a305a6842700000e3","content":"[simplest fm receiver](https://www.mikroe.com/ebooks/radio-receivers-from-crystal-set-to-stereo/the-simplest-fm-receiver)"},{"_id":"654ba94a305a6842700000e7","treeId":"655a38b74450703f0b0004a4","seq":16497936,"position":3,"parentId":"654f409a305a6842700000e3","content":"[electroluminescent receiver](http://www.pan-tex.net/usr/r/receivers/)"},{"_id":"653e0172167ad2eb3c000214","treeId":"655a38b74450703f0b0004a4","seq":16510987,"position":4,"parentId":"654f409a305a6842700000e3","content":"https://makezine.com/projects/super-simple-fm-transmitter/"},{"_id":"653dfab9167ad2eb3c000215","treeId":"655a38b74450703f0b0004a4","seq":16640126,"position":5,"parentId":"654f409a305a6842700000e3","content":"https://maker.pro/custom/tutorial/how-to-make-an-fm-transmitter"},{"_id":"653c2154e8acad334d000122","treeId":"655a38b74450703f0b0004a4","seq":16895596,"position":6,"parentId":"654f409a305a6842700000e3","content":"For example, there are quite a few ham data networks:\n\n* http://hamwan.org\n\n* https://hamnet.eu/\n\n* http://www.broadband-hamnet.org/\n\n* https://www.ampr.org/\n\n* https://www.arednmesh.org/\n\nHere is a [map](http://usercontent.arednmesh.org/K/5/K5DLQ/livemap2.html) of one of them."},{"_id":"626b1220001682e70f0002fa","treeId":"655a38b74450703f0b0004a4","seq":17224083,"position":6.5,"parentId":"654f409a305a6842700000e3","content":"feedlines [advanced]"},{"_id":"626a31f9001682e70f000301","treeId":"655a38b74450703f0b0004a4","seq":17106265,"position":0.5,"parentId":"626b1220001682e70f0002fa","content":"[energy transfer in DC circuits](http://www.abc.net.au/science/articles/2014/02/05/3937083.htm)"},{"_id":"626b1202001682e70f0002fb","treeId":"655a38b74450703f0b0004a4","seq":17104779,"position":1,"parentId":"626b1220001682e70f0002fa","content":"[telegraphers equations](https://en.wikipedia.org/wiki/Telegrapher%27s_equations)"},{"_id":"6261f6b7001682e70f00035b","treeId":"655a38b74450703f0b0004a4","seq":17111702,"position":1,"parentId":"626b1202001682e70f0002fb","content":"[via this question](https://physics.stackexchange.com/questions/221053/path-of-em-wave-propagation-in-a-circuit-wire)"},{"_id":"6261f60c001682e70f00035d","treeId":"655a38b74450703f0b0004a4","seq":17111698,"position":3,"parentId":"626b1220001682e70f0002fa","content":"[different explanation of the same](http://amasci.com/elect/poynt/poynt.html)"},{"_id":"62439a593c4d420b7b000361","treeId":"655a38b74450703f0b0004a4","seq":17140738,"position":4,"parentId":"626b1220001682e70f0002fa","content":"[about baluns](http://eznec.com/Amateur/Articles/Baluns.pdf)"},{"_id":"62b6ff30a7ef3106690007ec","treeId":"655a38b74450703f0b0004a4","seq":17222769,"position":7,"parentId":"654f409a305a6842700000e3","content":"[high-voltage DC power lines, why? ](https://www.youtube.com/watch?v=DFQG9kuXSxg)"}],"tree":{"_id":"655a38b74450703f0b0004a4","name":"Principles of Ham Radio","publicUrl":"principles-of-ham-radio","latex":true}}