Amateur Radio Basic Electronics.

Amateur Radio Basic Electronics

Class Schedule Topics Home Study Test
Radio Spectrum, Licensing and Methods (09/22) T1,T2,T7A/B Radio Phenomena (09/29) T3, Station Licensee and Control Op Duties (10/06) T4,T5 Good Operating Practices, Special Ops (10/13) T6,T9 Basic Electronics (10/20) T7 Good Engineering Practices (10/27) T8 Electrical, Antennas and RF Safety (11/03) T0 Review/Practice (11/10) All Home Study Reading Assignments Home Work Morse Code Test Nov 17th

T7 -- Basic Communications Electronics [3 Exam Questions -- 3 Groups]
T7A Fundamentals of electricity; AC/DC power; units and definitions of current, voltage, resistance, inductance, capacitance and impedance; Rectification; Ohm's Law principle (simple math); Decibel; Metric system and prefixes (e.g., pico, nano, micro, milli, deci, centi, kilo, mega, giga). T7B Basic electric circuits; Analog vs. digital communications; Audio/RF signal; Amplification. T7C Concepts of Resistance/resistor; Capacitor/capacitance; Inductor/Inductance; Conductor/Insulator; Diode; Transistor; Semiconductor devices; Electrical functions of and schematic symbols of resistors, switches, fuses, batteries, inductors, capacitors, antennas, grounds and polarity; Construction of variable and fixed inductors and capacitors. The questions contained within this pool must be used in all Technician examinations beginning July 1, 2003, and is intended to be used up through June 30, 2007. Question Pool ELEMENT 2 - TECHNICIAN CLASS as released by Question Pool Committee National Conference of Volunteer Examiner Coordinators December 4, 2002.

Analog and Digital Continuous Communication Modes Discrete (fixed)
SSB AM FM Amateur TV (ATV) Discrete (fixed) Communication Modes Radioteletype RTTY PSK31 CW

Conductors and Insulators
In a conductor, electric current can flow freely, in an insulator it cannot. Simply stated, most metals are good electrical conductors, most nonmetals are not. Metals are also generally good heat conductors while nonmetals are not. Conductors – Copper, Silver, Gold, Aluminum, Platinum, Steal, … Insulators – Glass, Wood, Rubber, Air, plastic … Note: Salt water is a Conductor, and so are you.

Voltage, Current, and Power
Voltage is also called Electromotive Force and is an electrical “pressure”. Current is a measure of the flow of electrons (volume) from the negative to positive poles. The load presents resistance to the flow of electrons. Voltage is measured across the positive and negative poles (in parallel) to measure the difference in “pressure”. To measure the electron flow, the meter must be placed in-line (in series) with the flow. Direct Current (DC) is a constant voltage source that causes current to flow in only one direction and has a positive and negative pole – like a battery. Alternating Current is what is available in the wall and the constantly changing polarity causes current to alternate directions.

Voltage, Current and Power (cont)
Potential – electrical pressure difference Electromotive Force (E) Units – Volts Unit Symbol V – 10V Measured across Flow – electron flow Current (I) Unites – Amps, Amperes Unit Symbol A – 0.1A Measured through Power (P) Watts Units – Watts Unit Symbol W – 60W P I E Potential – Voltage or Electromotive force Units are Volts named after Count Alessandro Giuseppe Antonio Anastasio Volta (Italian Inventor), invented the baterry. Flow – Current, measured in amps, named after André-Marie Ampère (French) scientist and mathematician Power – Measured in Watts, named after James Watt (Scottish/British) inventor

Voltage, Current, Ohm’s Law

Voltage, Current and Resistance - Ohm’s Law
Resistance (R ) Measure of conductivity Unit – Ohms Unit Symbol Ω - 100Ω Ohm’s law - Defines the relationship between Voltage, Current and Resistance E = I*R I = E/R R = E/I E I R Georg Simon Ohm (German/Bavarian) - Law of cnoduction P= E2/R P= I2*R

What about AC? For a sine (cosine) wave RMS = 0.707 * peak value
P(t) = E(t)*I(t) E(t) = I(t)*Z(t) -> for a given Frequency – E = I*Z Z = R+jX (Resistance + Reactance) P=E2(t)/R  “mean squared power” or “effective power” To determine the effective power, voltage or current, integrate (calculus) the squared signal– e.g. calculate the Route Mean Square value For a sine (cosine) wave RMS = * peak value Effective Voltage = VRMS = 0.707Vpeak Effective Current = IRMS = 0.707Ipeak Effective Power = VRMS*IRMS = VRMS2/R Need to account for the Phase Angle between Voltage and Current ( / ), but that is another lesson.

Black Boxes Rectifier – Converts AC to DC
Filter – Removes unwanted Frequencies High, Low, Band Pass, Band Stop Amplifier – Amplifies a signal Audio Amplifier – audio frequencies IF Amplifier – Intermediate Frequency Amplifier RF Amplifier – Radio Frequency Amplifier Modulator – Modulates two signals, generally a carrier and audio, and creates an output based on it transmission mode AM, FM, SSB, Pulse Modulation, CW Multiplier – multiplies the frequency Mixer – mixes two frequencies creating sum and difference (f0+f1, f0-f1) Modem – Modular / Demodulator – for digital communication TNC – Terminal Network Controller (Smart Modem) Transceiver – Transmitter and Receiver

Scaling and Units of Measurements
G M k h da d c m µ n p giga mega kilo hecto deca deci centi milli micro nano pico Power Watt (W) Voltage Volt (V) Current Ampere (A) Resistance Ohms (Ω) Capacitance Farad (F) Inductance Henry (H) Frequency Hertz (Hz) Farad – named after Michael Faraday (English) Chemist –electromagnetic force Henry – Joseph Henry (American) Scientist Hertz – Heinrich Rudolf Hertz (German)

Decibels (dB) dB = 10 log10 (Po/Pi) Human Hearing Dynamic Range
1/10th of a bel Named after Alexander Gram Bell Used to power loss in telephone lines The Ratio of Power In vs. Power Out dB = 10 log10 (Po/Pi) Symbols dBm => dB with Pi = 1 milliwatt dBk => db with Pi = 1000 watts dBµ => dB with Pi = 1 microwatt dBW => db with Pi = 1 watt dBF => db with Pi = 1 femtowatt Human Hearing Dynamic Range 120 dB -> 1 to 1,000,000,000,000 dB = 20 log10 Vout/Vin

Audio – Human Hearing Human hearing occurs in 2 dimension
Frequency 20 – 20K Hz Dynamic range - ~120dB of dynamic range (quietest to loudest) Most sensitive in the 2 – 4KHz range Normal Voice is 500 – 2KHz Low frequencies are vowels High frequencies are consonants More information in consonants Graph – done by Bell Labs – the experiment was to put someone in a quite room and adjust the sound level at 1KHz to just audio able, then change frequencies and plot.

T7A01 What is the name for the flow of electrons in an electric circuit?
A. Voltage B. Resistance C. Capacitance D. Current

T7A02 What is the name of a current that flows only in one direction?
A. An alternating current B. A direct current C. A normal current D. A smooth current

T7A03 What is the name of a current that flows back and forth, first in one direction, then in the opposite direction? A. An alternating current B. A direct current C. A rough current D. A steady state current

A. An alternating current
T7A03 What is the name of a current that flows back and forth, first in one direction, then in the opposite direction? A. An alternating current B. A direct current C. A rough current D. A steady state current

T7A04 What is the basic unit of electrical power?
A. The ohm B. The watt C. The volt D. The ampere

T7A05 What is the basic unit of electric current?
A. The volt B. The watt C. The ampere D. The ohm

T7A06 How much voltage does an automobile battery usually supply?
A. About 12 volts B. About 30 volts C. About 120 volts D. About 240 volts

T7A07 What limits the current that flows through a circuit for a particular applied DC voltage?
A. Reliance B. Reactance C. Saturation D. Resistance

T7A08 What is the basic unit of resistance?
A. The volt B. The watt C. The ampere D. The ohm

T7A09 What is the basic unit of inductance?
A. The coulomb B. The farad C. The henry D. The ohm

T7A10 What is the basic unit of capacitance?
A. The farad B. The ohm C. The volt D. The henry

T7A11 Which of the following circuits changes an alternating current signal into a varying direct current signal? A. Transformer B. Rectifier C. Amplifier D. Director

T7A12 What formula shows how voltage, current and resistance relate to each other in an electric circuit? A. Ohm's Law B. Kirchhoff's Law C. Ampere's Law D. Tesla's Law

T7A13 If a current of 2 amperes flows through a 50-ohm resistor, what is the voltage across the resistor? A. 25 volts B. 52 volts C. 100 volts D. 200 volts

T7A13 If a current of 2 amperes flows through a 50-ohm resistor, what is the voltage across the resistor? A. 25 volts B. 52 volts C. 100 volts D. 200 volts E 2 50 2*50 = 100

T7A14 If a 100-ohm resistor is connected to 200 volts, what is the current through the resistor?
A. 1 ampere B. 2 amperes C. 300 amperes D. 20,000 amperes

T7A14 If a 100-ohm resistor is connected to 200 volts, what is the current through the resistor?
A. 1 ampere B. 2 amperes C. 300 amperes D. 20,000 amperes 200 I 100 I = 200/100

T7A15 If a current of 3 amperes flows through a resistor connected to 90 volts, what is the resistance? A. 3 ohms B. 30 ohms C. 93 ohms D. 270 ohms

T7A15 If a current of 3 amperes flows through a resistor connected to 90 volts, what is the resistance? A. 3 ohms B. 30 ohms C. 93 ohms D. 270 ohms 90 3 R R = 90/3

T7A16 If you increase your transmitter output power from 5 watts to 10 watts, what decibel (dB) increase does that represent? A. 2 dB B. 3 dB C. 5 dB D. 10 dB

T7A17 If an ammeter marked in amperes is used to measure a 3000-milliampere current, what reading would it show? A amperes B. 0.3 amperes C. 3 amperes D. 3,000,000 amperes

T7A18 How many hertz are in a kilohertz?
B. 100 C. 1000 D. 1,000,000

T7A19. If a dial marked in megahertz shows a reading of 3
T7A19 If a dial marked in megahertz shows a reading of MHz, what would it show if it were marked in kilohertz? A kHz B kHz C kHz D. 3,525,000 kHz

T7A20 How many microfarads is 1,000,000 picofarads?
A microfarads B. 1 microfarad C microfarads D. 1,000,000,000 microfarads

T7A21 If you have a hand-held transceiver with an output of 500 milliwatts, how many watts would this be? A. 0.02 B. 0.5 C. 5 D. 50

T7B01 What type of electric circuit uses signals that can vary continuously over a certain range of voltage or current values? A. An analog circuit B. A digital circuit C. A continuous circuit D. A pulsed modulator circuit

T7B02 What type of electric circuit uses signals that have voltage or current values only in specific steps over a certain range? A. An analog circuit B. A digital circuit C. A step modulator circuit D. None of these choices is correct

T7B03 Which of the following is an example of an analog communications method?
A. Morse code (CW) B. Packet Radio C. Frequency-modulated (FM) voice D. PSK31

C. Frequency-modulated (FM) voice
T7B03 Which of the following is an example of an analog communications method? A. Morse code (CW) B. Packet Radio C. Frequency-modulated (FM) voice D. PSK31

T7B04 Which of the following is an example of a digital communications method?
A. Single-sideband (SSB) voice B. Amateur Television (ATV) C. FM voice D. Radioteletype (RTTY)

D. Radioteletype (RTTY)
T7B04 Which of the following is an example of a digital communications method? A. Single-sideband (SSB) voice B. Amateur Television (ATV) C. FM voice D. Radioteletype (RTTY)

T7B05 Most humans can hear sounds in what frequency range?
A Hz B ,000 Hz C ,000 Hz D. 10, ,000 Hz

T7B06 Why do we call electrical signals in the frequency range of 20 Hz to 20,000 Hz audio frequencies? A. Because the human ear cannot sense anything in this range B. Because the human ear can sense sounds in this range C. Because this range is too low for radio energy D. Because the human ear can sense radio waves in this range

B. Because the human ear can sense sounds in this range
T7B06 Why do we call electrical signals in the frequency range of 20 Hz to 20,000 Hz audio frequencies? A. Because the human ear cannot sense anything in this range B. Because the human ear can sense sounds in this range C. Because this range is too low for radio energy D. Because the human ear can sense radio waves in this range

T7B07 What is the lowest frequency of electrical energy that is usually known as a radio frequency?
A. 20 Hz B. 2,000 Hz C. 20,000 Hz D. 1,000,000 Hz

T7B08 Electrical energy at a frequency of 7125 kHz is in what frequency range?
A. Audio B. Radio C. Hyper D. Super-high

T7B09 If a radio wave makes 3,725,000 cycles in one second, what does this mean?
A. The radio wave's voltage is 3725 kilovolts B. The radio wave's wavelength is 3725 kilometers C. The radio wave's frequency is 3725 kilohertz D. The radio wave's speed is 3725 kilometers per second

C. The radio wave's frequency is 3725 kilohertz
T7B09 If a radio wave makes 3,725,000 cycles in one second, what does this mean? A. The radio wave's voltage is 3725 kilovolts B. The radio wave's wavelength is 3725 kilometers C. The radio wave's frequency is 3725 kilohertz D. The radio wave's speed is 3725 kilometers per second

Amplifying Components
Vacuum tubes are still used to provide very high outputs but require complicated high voltage power supplies. Transistors are very efficient small signal amplifiers using small voltages.

PNP and NPN Transistors
Most transistors are made of 3 pieces of semiconductor material: Collector, Base and Emitter. PNP (pointed in pointer) conducts when its base is more negative than its emitter. NPN (not pointed iN) conducts when its base is more positive than its emitter.

Vacuum Tubes Used for High Power amplification.
Note this triode conducts when its grid is more positive than the cathode. Compare to NPN transistor.

T7B10 Which component can amplify a small signal using low voltages?
A. A PNP transistor B. A variable resistor C. An electrolytic capacitor D. A multiple-cell battery

T7B11 Which component can amplify a small signal but normally uses high voltages?
A. A transistor B. An electrolytic capacitor C. A vacuum tube D. A multiple-cell battery

T7C01 Which of the following lists include three good electrical conductors?
A. Copper, gold, mica B. Gold, silver, wood C. Gold, silver, aluminum D. Copper, aluminum, paper

Resistors

Resistor Values

Resistances in Series and Parallel
In Series circuits: Rt = R1 + R2 + R3… In Parallel circuits: Rt = R1 x R2 R1+R2

Resistances in Series and Parallel
Rt = R1 + R2 Resistances in series are additive and limit current flow. Resistances in parallel reduce overall resistance by providing multiple current paths.

T7C02 What is one reason resistors are used in electronic circuits?
A. To block the flow of direct current while allowing alternating current to pass B. To block the flow of alternating current while allowing direct current to pass C. To increase the voltage of the circuit D. To control the amount of current that flows for a particular applied voltage

T7C03 If two resistors are connected in series, what is their total resistance?
A. The difference between the individual resistor values B. Always less than the value of either resistor C. The product of the individual resistor values D. The sum of the individual resistor values

D. The sum of the individual resistor values
T7C03 If two resistors are connected in series, what is their total resistance? A. The difference between the individual resistor values B. Always less than the value of either resistor C. The product of the individual resistor values D. The sum of the individual resistor values

Capacitors

Capacitors A capacitor is made by separating two conductive
plates by an insulator or dielectric. Capacitors store electrical energy in an electrostatic field. Capacitors tend to block DC and pass AC Voltage across a capacitor cannot change instantaneously V=Q/C C-> Area/distance Capacitors can be used to block DC, yet pass AC.

Capacitors in Parallel and Series
Capacitors add in parallel Ct = C1 + C2 + C3… In Series Ct = C1 x C2 C1 + C2 Note: this is backwards from resistors and inductors.

Variable Capacitor Capacitors store current electrostatically on their plates and opposes a change in voltage. Variable capacitors have rotating plates to change their value.

T7C04 What is one reason capacitors are used in electronic circuits?
A. To block the flow of direct current while allowing alternating current to pass B. To block the flow of alternating current while allowing direct current to pass C. To change the time constant of the applied voltage D. To change alternating current to direct current

T7C05 If two equal-value capacitors are connected in parallel, what is their total capacitance?
A. Twice the value of one capacitor B. Half the value of one capacitor C. The same as the value of either capacitor D. The value of one capacitor times the value of the other

A. Twice the value of one capacitor
T7C05 If two equal-value capacitors are connected in parallel, what is their total capacitance? A. Twice the value of one capacitor B. Half the value of one capacitor C. The same as the value of either capacitor D. The value of one capacitor times the value of the other

T7C06 What does a capacitor do?
A. It stores energy electrochemically and opposes a change in current B. It stores energy electrostatically and opposes a change in voltage C. It stores energy electromagnetically and opposes a change in current D. It stores energy electromechanically and opposes a change in voltage

T7C07 Which of the following best describes a variable capacitor?
A. A set of fixed capacitors whose connections can be varied B. Two sets of insulating plates separated by a conductor, which can be varied in distance from each other C. A set of capacitors connected in a series-parallel circuit D. Two sets of rotating conducting plates separated by an insulator, which can be varied in surface area exposed to each other

Inductors

Inductors If we form the conductor into a coil shape, we can
greatly intensify the strength of the magnetic field. We can store electrical energy in this magnetic Tends to pass DC and Block AC Current through and inductor cannot change Instantaneously, Inductors create an electromagnetic field used to store current. They can then oppose any change in current.

T7C08 What does an inductor do?
A. It stores energy electrostatically and opposes a change in voltage B. It stores energy electrochemically and opposes a change in current C. It stores energy electromagnetically and opposes a change in current D. It stores energy electromechanically and opposes a change in voltage

Diode Schematic Symbol
Diodes are only pass current in one direction and are often used as rectifiers to help convert AC to DC. Diode Schematic Symbol Current Flow

T7C09 What component controls current to flow in one direction only?
A. A fixed resistor B. A signal generator C. A diode D. A fuse

T7C10 What is one advantage of using ICs (integrated circuits) instead of vacuum tubes in a circuit?
A. ICs usually combine several functions into one package B. ICs can handle high-power input signals C. ICs can handle much higher voltages D. ICs can handle much higher temperatures

A. ICs usually combine several functions into one package
T7C10 What is one advantage of using ICs (integrated circuits) instead of vacuum tubes in a circuit? A. ICs usually combine several functions into one package B. ICs can handle high-power input signals C. ICs can handle much higher voltages D. ICs can handle much higher temperatures

Electronic Components
Fuse Var. Resistor Fixed Resistor Battery Variable Inductor Elect. Capacitor Variable Capacitor Chassis Grounds Antenna Earth Gnd Iron core transformer SPST Key components here are the switches, resistor, potentiometer (variable resistor), battery, NPN transistor, capacitor, antenna and iron core inductor. PNP Pentode Triode NPN DPDT DPST SPDT

T7C11 Which symbol of Figure T7-1 represents a fixed resistor?
A. Symbol 1 B. Symbol 2 C. Symbol 3 D. Symbol 5

T7C12 In Figure T7-1, which symbol represents a variable resistor or potentiometer?

T7C13 In Figure T7-1, which symbol represents a single-cell battery?

T7C14 In Figure T7-1, which symbol represents an NPN transistor?

T7C15 Which symbol of Figure T7-1 represents a fixed-value capacitor?

T7C16 In Figure T7-1, which symbol represents an antenna?

T7C17 In Figure T7-1, which symbol represents a fixed-value iron-core inductor?

T7C18 In Figure T7-2, which symbol represents a single-pole, double-throw switch?

T7C19 In Figure T7-2, which symbol represents a double-pole, single-throw switch?

Backup Slides

Voltage Pressure Analogy
A battery is analogous to a pump in a water circuit. A pump takes in water at low pressure and does work on it, ejecting it at high pressure. A battery takes in charge at low voltage, does work on it and ejects it at high voltage.

Kirchoff’s Current Law
The electric current, in amperes which flows into any junction in an electric circuit is equal to the current which flows out. This can be seen to be just a statement of conservation of charge (electrons). Since you do not lose any charge during the flow process around the circuit, the total current in any cross-section of the circuit is the same.

Kirchoff’s Current Law and Fluid Flow

Kirchoff’s Current Law and Fluid Flow
For any circuit, fluid or electric, which has multiple branches and parallel elements, the flowrate through any cross-section must be the same. This is sometimes called the principle of continuity.

Kirchoff’s Voltage Law
The voltage changes around any closed loop must sum to zero. No matter what path you take through an electric circuit, if you return to your starting point you must measure the same voltage, constraining the net change around the loop to be zero. Since voltage is electric potential energy per unit charge, the voltage law can be seen to be a consequence of conservation of energy. The voltage law has great practical utility in the analysis of electric circuits.

Kirchoff’s Voltage Law and Pressure

Kirchoff’s Voltage Law and Pressure (cont.)

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