5XJ Technician Study Guide

Welcome to the 5XJ Technician Study Guide

                    About This Guide: This comprehensive study material covers all topics on the FCC Technician Class Amateur Radio License exam. The Technician license is your gateway to the worldwide amateur radio community. With proper study using this guide, you can be well-prepared to pass the exam.
                

Questions on Exam

74%

Pass Score Required

Major Topics

How to Use This Guide

Study Each Section: Read through each major topic carefully. Don't rush—understanding is key.
Take Notes: Write down key concepts and formulas as you study.
Review Key Points: Pay special attention to boxes marked "Important" and "Key Concept."
Practice Questions: Answer all practice questions at the end of this guide.
Print or PDF: Use the buttons at the top to print or save this guide for offline study.

What is Amateur Radio?

Amateur radio (also called ham radio) is an international hobby and service enjoyed by millions of people worldwide. Hams use various types of radio equipment to communicate with each other, provide emergency communications, and support public service events.

Why Get a Ham Radio License?

Communicate with people worldwide using radio waves
Participate in emergency services and disaster relief
Join a worldwide community of radio enthusiasts
Learn about radio technology and electronics
Participate in contests and public service events
Help others during natural disasters and emergencies

Three Classes of Amateur Radio Licenses

License Class	Band Privileges	Questions on Exam
Technician	VHF/UHF primarily (144 MHz and above)	35 questions
General	HF bands (all frequencies up to 30 MHz)	35 questions
Amateur Extra	All amateur radio frequencies	50 questions

About the Technician License

The Technician class is the entry-level license. It grants you access to the VHF and UHF bands, where you can communicate locally through repeaters and via satellite. Most Technicians worldwide operate on the 2-meter band (144-148 MHz). This is an excellent entry point to ham radio.

FCC Rules & Regulations
Operating Procedures
Frequencies & Bands
Electrical Principles
Components & Circuits
Radio Wave Propagation
Antennas & Transmission Lines
Station Equipment
RF & Electrical Safety
Practice Questions & Answers

Continue to the next section to begin your study. You can navigate using the menu on the left.

1. FCC Rules & Regulations

Overview

The FCC (Federal Communications Commission) regulates all radio communications in the United States under Title 47, Part 97 of the Code of Federal Regulations (CFR). Understanding these rules is critical for passing the exam and operating legally.

Key Regulatory Concepts

What is the FCC?

The FCC is a U.S. government agency that regulates interstate and international communications by radio, television, wire, satellite, and cable.

Amateur Radio Service Purpose

According to FCC rules, the Amateur Radio Service is a radiocommunication service for the purpose of self-training, intercommunication, and technical investigations.

Call Signs

A call sign is a unique identifier assigned by the FCC to each licensed amateur radio operator. It consists of letters and numbers and must be used to identify your station during transmissions.

U.S. Call Sign Format: A prefix (1-2 letters), a digit (0-9), and a suffix (1-3 letters)

Example: W5NF means "W" (USA), "5" (Region 5, includes Texas), "NF" (personal identifier)

License Terms and Types

License Feature	Details
Initial Term	10 years
Renewal Period	10 years
Grace Period	2 years (can renew after expiration)
Operator Class Upgrade	Can upgrade at any time by passing exam

Operating Rule Requirements

Station Identification

CRITICAL RULE: You MUST identify your station at the beginning and end of each communication, and at least every 10 minutes during longer communications. Always transmit your call sign.

Call Sign Usage During Transmissions

Transmit your call sign at least every 10 minutes
Always identify before ending a transmission
Use only authorized phonetic alphabet if needed (Alpha, Bravo, Charlie, etc.)
Identify in English using only the letters and digits of your call sign

Prohibited Transmissions

These transmissions are NEVER allowed:

Music, whistling, or sound effects
Obscene, indecent, or profane language
Messages intended to facilitate illegal activities
Encoded messages (except for satellite operations with FCC authorization)
Communications in a language other than English (with specific exceptions)
False or deceptive signals (CQ calls, etc.)

Authorized Modes of Transmission

Technicians are primarily authorized for:

Voice (SSB, FM)
CW (Morse Code)
Digital modes (RTTY, PSK31, Packet)
Image modes (Slow-scan TV)

Frequency Coordination and Sharing

Repeater Control

A repeater is an automated transmitting station that receives on one frequency and retransmits on another. Technicians use repeaters extensively for local communications.

Important: The FCC requires repeater owners to coordinate frequencies to prevent interference. Never operate a repeater without proper authorization and coordination.

Interference and Power Limits

Technician Maximum Power: 1500 watts PEP (Peak Envelope Power)
You must minimize interference to other stations
If you cause harmful interference, you must cease transmission immediately
Use the minimum power necessary to maintain communications

License Privileges

What Can Technicians Do?

Privilege	Details
Receive	Listen on any frequency
Transmit VHF/UHF	All frequencies 50 MHz and above
HF CW Only	Limited CW privileges on some HF bands
Repeater Use	Full access to VHF/UHF repeaters
Satellite	Full access to amateur satellites

FCC Violations and Penalties

Serious violations can result in:

Cease and desist orders
Fines up to $10,000
License denial or revocation
Criminal prosecution in severe cases

Remember: Operate with integrity and follow all FCC rules. The amateur radio community depends on responsible operators!

2. Operating Procedures

Introduction to Ham Radio Etiquette

Operating Procedure Basics: Amateur radio operators follow specific procedures to ensure clear communication, prevent interference, and maintain a professional, courteous environment on the air.

Simplex vs. Repeater Operation

Simplex Communication

Definition: Direct radio-to-radio communication where both stations transmit and receive on the same frequency.

Used for: Direct point-to-point contacts
Range: Limited by terrain and power
Frequency: Single frequency (e.g., 146.52 MHz - the national Technician calling frequency)

Repeater Communication

Definition: Communication through an automated station that receives your transmission on one frequency (input) and retransmits it on another (output).

How Repeaters Work:

You transmit on the INPUT frequency
The repeater receives your signal
The repeater simultaneously transmits on the OUTPUT frequency
Other stations hear you on the OUTPUT frequency

Repeater Offset

The difference between input and output frequencies is called the "offset." Common offsets:

2-meter band: +/- 600 kHz offset
70-centimeter band: +/- 5 MHz offset

Repeater Etiquette

Essential Repeater Operating Rules

Use Proper Spacing: Leave 1-2 seconds of silence between transmissions for the repeater to process
Identify Regularly: Identify your call sign every 10 minutes and at the end of contact
Keep Transmissions Brief: Speak clearly and concisely; don't monopolize the repeater
Use Your Callsign: Always use your official FCC call sign
Check the Frequency: Listen before transmitting to avoid interference
Use Repeater Courtesy: Pause between exchanges to allow others to transmit

Repeater Offset and Direction Indicators

Indicator	Meaning
+ (Plus)	Transmit on a frequency 600 kHz (2m) or 5 MHz (70cm) above the listed frequency
- (Minus)	Transmit on a frequency 600 kHz (2m) or 5 MHz (70cm) below the listed frequency
No Symbol	Simplex (transmit and receive on same frequency)

Common Operating Phrases

Standard Phonetic Alphabet

Use this to spell out call signs or difficult words:

Letter	Phonetic	Letter	Phonetic
A	Alpha	N	November
B	Bravo	O	Oscar
C	Charlie	P	Papa
D	Delta	Q	Quebec
E	Echo	R	Romeo
F	Foxtrot	S	Sierra
G	Golf	T	Tango
H	Hotel	U	Uniform
I	India	V	Victor
J	Juliet	W	Whiskey
K	Kilo	X	X-ray
L	Lima	Y	Yankee
M	Mike	Z	Zulu

Common Q-Codes and Abbreviations

Code	Meaning
QSY	Change frequency
QSO	A two-way conversation
QTH	My location is...
RST	Readability, Signal strength, Tone (Morse code report)
73	Best regards (end of conversation)
88	Love and kisses (informal)

Signal Reports

RST Report (Readability-Signal-Tone)

Used primarily in CW (Morse Code) communications:

R (Readability): 1-5 scale (1 = unreadable, 5 = perfectly readable)
S (Signal Strength): 1-9 scale (1 = faint, 9 = extremely strong)
T (Tone): 1-9 scale (1 = very rough, 9 = perfect)

Example:

"Your signal is 5-9-9" means: Perfectly readable, Extremely strong, Perfect tone

Emergency Communications

Priority of Communications

On amateur radio, there's an understood priority:

Emergency: Life and property in immediate danger
Urgent: Important safety information
Welfare Inquiry: Checking on someone's wellbeing
Routine: Normal amateur radio communications

Mayday and SOS

Mayday: Used for voice communications in life-threatening emergencies. Say "MAYDAY" three times, slowly and clearly.

SOS: Used in CW (Morse Code) for emergencies: three dots, three dashes, three dots (···---···).

General Operating Conduct

Best Practices

Always listen before transmitting
Speak in a natural, conversational manner
Avoid excessive use of jargon
Be respectful to all operators
Never transmit offensive or inappropriate language
Know your equipment and frequencies
Keep transmissions brief and clear
Be courteous and patient with new operators

3. Frequencies & Bands

Understanding Frequency and Wavelength

Key Definitions

Frequency: The number of radio waves passing a point per second, measured in Hertz (Hz). Higher frequencies = more waves per second.

Wavelength: The distance between consecutive wave peaks. Inversely related to frequency.

Frequency Formula

                    Wavelength (meters) = 300,000,000 ÷ Frequency (Hz)
                    
                    Or for simpler calculation:
                    
                    Wavelength (meters) = 300 ÷ Frequency (MHz)

Example Calculation

The 2-meter band center frequency is 146 MHz.
Wavelength = 300 ÷ 146 = 2.05 meters ≈ 2 meters
That's where the "2-meter band" name comes from!

VHF and UHF Bands for Technicians

Primary Technician Bands

Band Name	Frequency	Wavelength	Usage
6 Meter	50.0-54.0 MHz	6 meters	SSB, CW, weak signal work, satellites
2 Meter	144-148 MHz	2 meters	Most popular Technician band; repeaters, FM, SSB
70 Centimeter	420-450 MHz	70 cm	Repeaters, FM, weak signal work
33 Centimeter	902-928 MHz	33 cm	Amateur packet radio, weak signal
23 Centimeter	1240-1300 MHz	23 cm	Weak signal, satellite, amateur television

Technician Frequency Allocations

2-Meter Band (144-148 MHz)

144.000-144.100 MHz: Weak signal SSB/CW
144.100-144.300 MHz: CW and SSB
144.300-144.500 MHz: Beacons, repeater inputs
144.500-144.600 MHz: FM simplex (Calling frequency: 146.52 MHz)
144.600-145.300 MHz: Repeater outputs and inputs
145.300-145.500 MHz: FM simplex
145.500-146.000 MHz: Satellite and other modes
146.000-146.400 MHz: FM repeater outputs
146.400-146.600 MHz: FM simplex and repeater inputs
146.600-147.600 MHz: FM repeater outputs and inputs

Important Frequencies

Frequency	Purpose	Mode
146.52 MHz	National Technician calling frequency (2m)	FM Simplex
1.25 MHz (center)	6m calling frequency	SSB/CW
50.125 MHz	6m calling frequency	CW
70cm band	Varies by repeater	FM Repeater

Band Characteristics

How Bands Differ

Characteristic	Lower Frequencies (6m)	Higher Frequencies (2m, 70cm)
Propagation	Long-distance via ionosphere	Line-of-sight primarily
Antenna Size	Larger antennas needed	Smaller, more portable antennas
Typical Usage	Long-distance, weak signal	Local repeaters, portable
Repeater Common?	Less common	Very common (2m especially)

Frequency Coordination

What is Frequency Coordination?

Frequency coordination is the process of assigning frequencies to repeaters to prevent interference. Most areas have a Frequency Coordinator who approves new repeater frequencies.

Why It's Important

Prevents interference between repeaters
Ensures efficient use of limited frequencies
Maintains quality communications
Protects the amateur radio spectrum

Temporary Frequencies and Waivers

Special Use Authorizations

The FCC may grant temporary frequencies for:

Emergency communications during disasters
Special events and contests
International expeditions
Experimental modes and techniques

4. Electrical Principles

Basic Electrical Concepts

Three Fundamental Quantities

Voltage (V): The electrical potential difference, measured in Volts. Think of it as the pressure that pushes electrons through a circuit.

Current (I): The flow of electrons, measured in Amperes (Amps). This is the actual movement of electricity.

Resistance (R): Opposition to current flow, measured in Ohms (Ω). This is what slows down or stops electron movement.

Ohm's Law

The Most Important Formula in Electronics

                    V = I × R
                    
                    Voltage = Current × Resistance
                    
                    You can rearrange this for any unknown:
                    
                    I = V ÷ R (Current = Voltage ÷ Resistance)
                    
                    R = V ÷ I (Resistance = Voltage ÷ Current)

Ohm's Law Examples

Example 1: A circuit has 12 volts and 4 ohms of resistance. What is the current?
I = V ÷ R = 12 ÷ 4 = 3 Amperes

Example 2: A circuit has 9 volts and 3 amperes of current. What is the resistance?
R = V ÷ I = 9 ÷ 3 = 3 Ohms

Power

Electrical Power Formula

                    P = V × I
                    
                    Power = Voltage × Current (measured in Watts)
                    
                    Related formulas:
                    
                    P = I² × R (Power = Current squared × Resistance)
                    
                    P = V² ÷ R (Power = Voltage squared ÷ Resistance)

Power Example

A radio transmitter operates at 12 volts with a final amplifier drawing 10 amps. What is the power output?

P = V × I = 12 × 10 = 120 Watts

Series and Parallel Circuits

Series Circuits

Definition: Components connected end-to-end in a single path. Current flows through each component in sequence.

Characteristics:

Same current through all components
Voltages add up
Resistances add up
If one component fails, circuit breaks

Parallel Circuits

Definition: Components connected to the same two points. Current splits between paths.

Characteristics:

Same voltage across all components
Current splits between paths
Total resistance is less than any single resistor
If one path fails, others still work

Calculating Parallel Resistance

For two resistors in parallel:

R = (R₁ × R₂) ÷ (R₁ + R₂)

AC vs. DC Electricity

DC (Direct Current)

Electrons flow in one direction only
Constant voltage
Used in: Batteries, radio power supplies

AC (Alternating Current)

Electrons flow back and forth
Voltage alternates positive and negative
In USA: 60 Hz (60 cycles per second)
Used in: AC power outlets, antenna signal transmission

Frequency and Wavelength

Understanding Radio Frequency

Radio waves are alternating electromagnetic signals. The frequency tells you how many times per second the wave oscillates.

                    Frequency (Hz) = Speed of Light ÷ Wavelength (meters)
                    
                    Or: Wavelength (m) = 300,000,000 ÷ Frequency (Hz)
                    
                    Simplified: Wavelength (m) = 300 ÷ Frequency (MHz)

Impedance

What is Impedance?

Impedance (Z) is the total opposition to current flow in an AC circuit. It combines resistance and reactance (from capacitors and inductors).

Characteristic Impedance

Each transmission line has a characteristic impedance:

Coaxial cable: Typically 50 ohms or 75 ohms
Ladder line: 300-600 ohms

Decibels (dB)

Understanding Decibels

A decibel is a ratio comparing one power level to another or one voltage to another. It's used to express gain (amplification) and loss (attenuation).

Power ratio: dB = 10 × log₁₀(P₁/P₂)
Voltage ratio: dB = 20 × log₁₀(V₁/V₂)

Common dB Values to Remember

dB Value	Power Ratio	Meaning
3 dB	2×	Doubles the power
6 dB	4×	Quadruples the power
10 dB	10×	Multiplies power by 10
-3 dB	½	Half the power
-10 dB	⅟₁₀	One-tenth the power

5. Components & Circuits

Resistors

What is a Resistor?

A resistor is a component that opposes the flow of current. It controls current and reduces voltage.

Resistor Color Codes

Resistor values are marked with colored bands. The standard bands are:

Color	Digit	Multiplier	Tolerance
Black	0	×1	—
Brown	1	×10	±1%
Red	2	×100	±2%
Orange	3	×1,000	—
Yellow	4	×10,000	—
Green	5	×100,000	±0.5%
Blue	6	×1,000,000	±0.25%
Violet	7	×10,000,000	±0.1%
Gray	8	×100,000,000	—
White	9	×1,000,000,000	—
Gold	—	×0.1	±5%
Silver	—	×0.01	±10%

Reading Resistor Codes

A resistor has bands: Brown-Black-Red-Gold

1st band (Brown) = 1
2nd band (Black) = 0
Multiplier (Red) = ×100
Tolerance (Gold) = ±5%

Value = 10 × 100 = 1,000 Ohms = 1 kΩ ±5%

Capacitors

What is a Capacitor?

A capacitor is a component that stores electrical charge. It consists of two conductors separated by an insulator (dielectric).

Capacitor Characteristics

Blocks DC current but passes AC current
Capacitance measured in Farads (F)
Common units: microfarads (μF), nanofarads (nF), picofarads (pF)
Higher capacitance = more charge stored

Capacitor Types

Type	Characteristics	Uses
Ceramic	Small, low capacitance, cheap	Filtering, tuning
Electrolytic	Polarized, high capacitance	Power supply filtering
Mica	Stable, low loss	RF circuits, filters
Variable	Capacitance adjustable	Tuning circuits, receivers

Inductors

What is an Inductor?

An inductor is a coil of wire that creates a magnetic field when current flows through it. It opposes changes in current.

Inductor Characteristics

Passes DC but opposes AC
Inductance measured in Henries (H)
Common units: millihenries (mH), microhenries (μH)
More turns = more inductance

Transistors

What is a Transistor?

A transistor is a semiconductor device that can amplify signals or act as a switch. It's fundamental to all modern electronics.

Two Main Types

Type	Full Name	Terminals	Uses
BJT	Bipolar Junction Transistor	Base, Collector, Emitter	Amplification, switching
FET	Field Effect Transistor	Gate, Drain, Source	High-impedance amplification

Diodes

What is a Diode?

A diode is a semiconductor that allows current to flow in only one direction. It has two terminals: Anode (+) and Cathode (-).

Common Diode Types

Type	Purpose	Application
Rectifier	Converts AC to DC	Power supplies
Zener	Voltage regulation	Power supply regulation
LED	Emits light	Indicators, displays
Varactor	Variable capacitance	Tuning circuits

Integrated Circuits (ICs)

What is an Integrated Circuit?

An IC is a complete circuit with many transistors, resistors, and capacitors built on a single semiconductor chip. Common types include:

Operational Amplifiers (Op-Amps)
Voltage Regulators
Microcontrollers
Digital Logic Chips

Power Supplies

Basic Power Supply Function

A power supply converts AC line voltage to regulated DC voltage:

Transformer: Reduces AC voltage to desired level
Rectifier: Converts AC to DC (using diodes)
Filter: Smooths the DC (using capacitors and inductors)
Regulator: Maintains constant voltage (using Zener or IC regulator)

Filters

Types of Filters

Filter Type	Function	Passes	Blocks
Low-Pass	Reduces high frequencies	Low frequencies	High frequencies
High-Pass	Reduces low frequencies	High frequencies	Low frequencies
Band-Pass	Passes specific frequency range	Within band	Outside band
Notch	Blocks specific frequency	All except center	Center frequency

6. Radio Wave Propagation

How Radio Waves Travel

Three Main Propagation Modes

Radio waves travel from transmitter to receiver through different mechanisms depending on frequency, time of day, and atmospheric conditions.

Ground Wave Propagation

What is Ground Wave?

Ground wave propagation occurs when radio waves travel along the Earth's surface. The ground helps bend the waves around the Earth's curvature.

Characteristics

Used primarily on low and medium frequencies
Most reliable mode
Range: 50-100+ miles depending on frequency and power
Works day and night
More effective over water (sea water conducts better)

Ionospheric Propagation (Skywave)

What is the Ionosphere?

The ionosphere is a layer of ionized gas high in the atmosphere (40-250 miles up). Radio waves can bounce off this layer.

How Skywave Works

Radio wave is transmitted at an angle toward the sky
Wave reaches the ionosphere and is refracted (bent)
Wave is bent back toward Earth
Wave is received at a distant location
Wave may bounce again (multiple hops)

Factors Affecting Skywave

Frequency: Lower frequencies reflect better (HF is best for long distance)
Time of day: Better propagation at night
Season: Varies throughout the year
Solar activity: Sunspot cycles affect ionosphere
Angle of transmission: Critical angle affects distance

Skip Zone

The "skip zone" is an area where a transmitted signal cannot be received. It occurs between the ground wave range and where skywave returns to Earth.

Line-of-Sight Propagation

VHF and UHF Propagation

VHF (50-300 MHz) and UHF (300-3000 MHz) signals travel primarily by line-of-sight. They don't refract off the ionosphere. This is why repeaters are used for range.

Characteristics

Range limited by radio horizon
Range approximately: 1.4 × √(height in feet) miles
Affected by terrain and buildings
Sporadic modes can extend range temporarily

Calculating Radio Horizon

A repeater antenna is at 100 feet height.
Range ≈ 1.4 × √100 = 1.4 × 10 = 14 miles

A portable at 6 feet can reach the repeater from about:
Range ≈ 1.4 × √6 = 1.4 × 2.45 = 3.4 miles

Anomalous Propagation Modes

Tropospheric Scatter

Radio waves can scatter off irregularities in the troposphere (lowest layer of atmosphere), extending range to 200-300 miles. Occurs during temperature inversions.

Ducting

A layer of atmosphere bends radio waves in a waveguide-like manner, extending range to hundreds of miles. Also called "atmospheric ducting."

Sporadic E-Layer (Es)

Occasional ionization in the E-layer (60-70 miles altitude) can reflect VHF signals over long distances. Can allow 2-meter contacts 500+ miles.

Meteor Scatter

Ionized trails from meteors can reflect radio waves. Used for brief, long-distance communications.

Aurora Propagation

The aurora (Northern Lights) creates an ionized area that can reflect VHF signals over long distances, typically at northerly latitudes.

Atmospheric Effects on Radio Propagation

Absorption

Water vapor and oxygen in the atmosphere absorb radio waves, especially at higher frequencies and during rain.

Fading

Signal strength variations caused by multipath propagation (signal arriving via multiple paths that interfere).

Polarization Effects

Radio waves can be polarized vertically or horizontally. Best reception occurs when transmitter and receiver use the same polarization.

Maximum Usable Frequency (MUF)

What is MUF?

The Maximum Usable Frequency (MUF) is the highest frequency that the ionosphere will reflect back to Earth. It varies with time of day, season, and solar activity.

Factors Affecting MUF

Solar activity (sunspots increase MUF)
Time of day (usually higher during day)
Season (higher in summer)
Latitude (varies with geographic location)

Critical Angle

What is Critical Angle?

The angle at which a radio wave must be transmitted to use skywave propagation efficiently. Too steep an angle will pass through the ionosphere.

Angle of Radiation

Low angle (2-15°): Long distance skywave
Medium angle (15-30°): Medium distance
High angle (30°+): Short distance or local skip

7. Antennas & Transmission Lines

What is an Antenna?

Basic Antenna Function

An antenna is a conductor that converts electrical signals into radio waves (transmission) or radio waves into electrical signals (reception). It's the interface between your transmitter/receiver and the radio waves.

Antenna Characteristics

Resonance and Length

Antennas are most efficient when their length relates to the wavelength:

½ wavelength (dipole): Most common, simple
¼ wavelength (monopole): Vertical antennas, needs ground plane
5/8 wavelength: Improved gain

Calculating Antenna Length

                    Antenna Length = Wavelength ÷ 2 (for ½ wave dipole)
                    
                    Using simplified formula:
                    
                    Length (feet) = 468 ÷ Frequency (MHz)
                    
                    For ¼ wavelength:
                    
                    Length (feet) = 234 ÷ Frequency (MHz)

Example Antenna Calculations

2-Meter Band center frequency: 146 MHz

½ wave dipole length = 468 ÷ 146 = 3.2 feet (38 inches)

¼ wave vertical = 234 ÷ 146 = 1.6 feet (19 inches)

Common Antenna Types for Technicians

Dipole Antenna

Description: Simple two-element antenna, ½ wavelength long

Advantages:

Simple to build
Effective performance
No ground plane needed

Uses: General purpose, portable stations

Vertical Antenna

Description: Single element ¼ wavelength, standing vertical

Advantages:

Omnidirectional (360°)
Compact
Good for repeater use

Requires: Ground plane (radials)

Yagi Antenna

Description: Directional antenna with driven element, reflector, and directors

Advantages:

High gain (directional amplification)
Rejects interference from other directions

Uses: Weak signal work, satellite

Helical Antenna

Description: Coiled wire antenna, often used for UHF

Advantages:

Compact
Moderate gain
Right-hand or left-hand polarization

Ground Plane Antenna

A ¼ wavelength vertical element mounted above a ground plane (conducting surface or radials). Commonly used in mobile and base stations.

Antenna Gain

Understanding Gain

Antenna gain is the amplification of signal in the direction of maximum radiation compared to a reference antenna (usually an isotropic radiator).

Gain Measurements

dBi: Decibels relative to isotropic radiator
dBd: Decibels relative to dipole
Relationship: dBi = dBd + 2.15

Typical Gains

Antenna Type	Typical Gain
Dipole	0 dBd (2.15 dBi)
Vertical (¼ wave)	-3 dBd
2-element Yagi	5-6 dBd
3-element Yagi	8-9 dBd

Polarization

Types of Polarization

Vertical: Antenna is vertical (perpendicular to ground)
Horizontal: Antenna is horizontal
Circular: Antenna radiates waves that spiral (used in satellite work)

Polarization Matching

Best reception occurs when transmitting and receiving antennas use the same polarization. A vertical transmitter works best with a vertical receiver. Mismatched polarization causes loss of 20 dB or more!

Transmission Lines (Feed Lines)

Purpose of Transmission Lines

Transmission lines carry RF energy from your transmitter to the antenna (or from antenna to receiver). Quality matters!

Common Types

Type	Impedance	Uses	Advantages/Disadvantages
RG-58 Coax	50Ω	Mobile/portable	Flexible but lossy at higher frequencies
RG-8 Coax	50Ω	Base station	Lower loss, larger diameter
LMR-400	50Ω	Professional use	Very low loss
Ladder Line	300-600Ω	HF dipoles	Low loss but requires careful routing

Cable Loss

Coaxial cable loss increases with:

Higher frequency (loss roughly doubles with doubling frequency)
Longer cable length
Poor quality cable
Bending or damage

Example Cable Loss (100 feet of RG-8)

Frequency	Loss
146 MHz (2m)	~0.7 dB
440 MHz (70cm)	~2.0 dB
1.2 GHz (23cm)	~4.5 dB

Impedance Matching

Why Impedance Matching Matters

When transmitter impedance, transmission line impedance, and antenna impedance all match (typically 50Ω), maximum power is transferred and reflections are minimized.

Mismatch Problems

Power reflects back toward transmitter (VSWR increases)
Power is not radiated efficiently
Heat is generated in the transmitter
Can damage transistors in some transmitters

Standing Wave Ratio (SWR)

SWR is the ratio of maximum voltage to minimum voltage on a transmission line. It indicates how well impedances are matched.

SWR 1:1 = Perfect match (ideal)
SWR 1.5:1 = Good (acceptable)
SWR 2:1 = Fair (workable)
SWR 3:1 or higher = Poor (fix needed)

8. Station Equipment

Transmitter and Receiver Functions

Transmitter

Function: Converts audio signals and data into radio waves

Major Components:

Microphone/Input: Captures audio or data
Modulator: Applies signal to RF carrier
RF Oscillator: Generates carrier frequency
Power Amplifier: Amplifies RF signal to desired power
Antenna: Radiates signal into space

Receiver

Function: Converts radio waves into audio or data

Major Components:

Antenna: Receives weak signal
Front-End Filter: Rejects unwanted frequencies
RF Amplifier: Amplifies weak received signal
Mixer: Converts to intermediate frequency
IF Amplifier: Amplifies intermediate frequency signal
Detector: Recovers audio from RF
Audio Amplifier: Amplifies audio to speaker level
Speaker: Converts audio to sound

Transceiver

What is a Transceiver?

A transceiver combines a transmitter and receiver in a single unit. Most amateur radio equipment today is transceiver-based. The same antenna is used for both transmitting and receiving.

Modern VHF/UHF Transceivers

Features typically include:

Frequency coverage of entire band
Memory channels for favorite frequencies
Automatic repeater offset
CTCSS/DCS (tone/digital codes for repeater access)
VOX (Voice Operated Switch)
Low/medium/high power settings
Dual receive (monitoring two frequencies)

Power Supply

12V DC Power Supply

Most portable and mobile transceivers operate from 12 or 13.8 volts DC. A quality power supply is essential for reliable operation.

Requirements

Voltage: 13.8V DC nominal
Current Rating: At least as much as the radio's maximum draw
Regulation: Should maintain voltage despite load changes
Filtering: Should have good RF filtering to prevent noise

Calculating Power Supply Size

A 100-watt transceiver at 13.8V
I = P ÷ V = 100 ÷ 13.8 = 7.2 Amps

You should use a power supply rated for at least 10-15 amps

Microphone

Microphone Characteristics

Dynamic: Rugged, good for mobile, moving coil design
Condenser: Sensitive, requires power, used in base stations
Electret: Hybrid, good sensitivity without external power

Impedance Matching

Microphone impedance should match transmitter input (typically 50-600 Ω). Mismatch causes low audio or distortion.

Headphones and Speaker

Headphones

Reduce RF interference (shielded cables)
Privacy in multi-person stations
Reduce ambient noise
Typical impedance: 8-32 Ω

Speakers

Built-in or external
External speakers often provide better audio quality
Typical impedance: 4-8 Ω

Dummy Load

Purpose

A dummy load (also called a dummy antenna or RF load) is a 50Ω resistor used to:

Test transmitter without radiating signals
Tune transmitter circuits
Adjust power levels safely
Prevent unintended interference

Important

Always use a dummy load when testing and tuning equipment. Never transmit unnecessarily on the air.

Test Equipment

SWR Meter

Measures Standing Wave Ratio to verify antenna tuning. Used between transmitter and antenna to detect mismatch.

Multimeter

Measures voltage, current, and resistance. Essential for troubleshooting power supply and equipment problems.

Frequency Counter

Verifies that transmitter is operating on the correct frequency.

RF Power Meter

Measures actual transmitter power output.

Filters and Duplexers

Low-Pass Filter

Removes harmonics (undesired high-frequency components) from transmitter output. Required by FCC to reduce interference.

Band-Pass Filter

Passes only frequencies within a specific band, rejecting interference outside the band.

Duplexer

Allows simultaneous transmission and reception on a repeater by separating transmit and receive frequencies.

Mobile Installation

Safe Mobile Operation

Keep radio adjusted safely while driving
Use minimal power to reduce RF exposure
Install antenna for best performance and safety
Use mobile bracket designed for the radio
Keep hands free (use PTT switch on microphone)

Antenna Mounting

Roof Mount: Best performance, clear 360° pattern
Trunk Mount: Good performance, easier to remove
Gutter Mount: Acceptable, less intrusive
Mirror Mount: Convenient but reduced performance

9. RF & Electrical Safety

RF Radiation Safety

What is RF Radiation?

Radio frequency (RF) radiation is electromagnetic energy transmitted by your antenna. At high power levels, RF energy can cause biological effects.

Biological Effects of RF

Non-ionizing RF radiation causes heating of body tissue. Potential effects include:

Temporary temperature rise in affected tissues
Cataracts (eye lens damage) at high exposures
Reduced sperm counts (testicular heating)
Burns at very high power levels

FCC RF Safety Limits

The FCC has established maximum permitted exposure levels (MPE) for RF radiation. Technicians must comply with these limits.

Occupational/Controlled: More permissive (for trained people aware of RF)
General Population/Uncontrolled: More restrictive (for general public)

Common Frequencies and Limits

Frequency	Controlled (mW/cm²)	Uncontrolled (mW/cm²)
50 MHz	2	1
146 MHz (2m)	5	1
440 MHz (70cm)	10	1
900+ MHz	10	1

RF Safety Practices

Safe Operating Procedures

Know Your Power Levels: Higher power = greater RF exposure
Use Minimum Power: Use low power when possible (many transceivers have 1W/5W/25W settings)
Antenna Awareness: Keep away from antennas during transmission
Avoid Feeding Cables: Don't place your head near feed lines during transmission
Mobile Considerations: Don't transmit with antenna near occupants
Repeated Exposures: Limit duration of high-power transmissions

RF Safety Labels and Signs

Required on amateur radio equipment:

Warning labels on transmitters
Caution signs near antennas
Documentation of RF exposure assessment

Electrical Safety

High Voltage Hazards

DANGER: Amateur radio equipment can contain lethal voltages (60V AC in power supplies, kilovolts in tube equipment). Never work on equipment without proper training!

Safe Electrical Practices

Disconnect Power: Always unplug equipment before servicing
Discharge Capacitors: Even with power off, capacitors can hold dangerous charge. Discharge with an insulated tool
Use Proper Tools: Insulated screwdrivers for live circuit work
Never Touch Unknown Circuits: If you don't know what it is, don't touch it
Wear Protection: Avoid metal jewelry that could short circuits
Proper Grounding: Use grounding straps when handling sensitive components

Power Supply Safety

Common Hazards

Primary AC supply can be lethal (120V or 240V)
Output capacitors may be charged to dangerous levels
Transformer secondary can have high voltage before rectification

Safe Testing

Use voltmeter to verify power before touching components
Discharge capacitors across test leads (don't use your fingers)
Test for voltage before and after discharge
Never power up unknown or repaired equipment without protection

Antenna Safety

Mechanical Hazards

Antenna towers and masts can fall (engineering required for installation)
Wind loads on antennas are significant
Guy wires can be tripping hazards
Proper grounding of towers protects against lightning

Proper Installation

Use professional installation for large antennas
Follow engineering specifications
Ensure proper grounding and lightning protection
Clear antennas from power lines
Maintain safe distance from antennas when transmitting

Lightning Safety

Protection

Install lightning arrestor on antenna feed line
Ground the antenna system properly
Use coax disconnection safety switch
During electrical storms: disconnect antennas

Microwave Radiation Safety (GHz Frequencies)

Special Considerations

Microwave frequencies (900 MHz and above) require special care
Reflections from dishes and waveguides can concentrate radiation
Never look into parabolic reflector while transmitting
Keep clear of klystron or other high-power microwave sources

Safety Equipment

Recommended Tools and Supplies

Multimeter for voltage testing
Insulated screwdrivers
Safety glasses for component removal
Grounding strap
RF power meter (to verify safe levels)
First aid kit
Fire extinguisher (Class C for electrical fires)

Emergency Response

If someone is electrocuted:

Do NOT touch the person while they're in contact with live circuit
Disconnect power immediately
Call emergency services
Perform CPR if trained

Practice Questions for Technician License Exam

This section contains representative practice questions covering all topics on the FCC Technician license exam. The actual exam draws from a larger question pool, but practicing with these will help you understand the types of questions you'll encounter.

FCC Rules and Operating Procedures

1. What must you do to become an amateur radio operator?

Answer: D

Pass the Technician license exam. The exam covers FCC rules, operating procedures, basic electronics, and radio theory.

2. How often must you identify your amateur radio station?

Answer: B

At least every 10 minutes during communication and at the end of each communication. This is an FCC requirement.

3. What is the maximum power output for a Technician license holder?

Answer: 1500 watts PEP

Technicians are authorized up to 1500 watts PEP (Peak Envelope Power) on their assigned bands. Most operators use much less power.

4. What does "simplex" mean in amateur radio?

Answer: Direct communication on the same frequency

Simplex is when two stations communicate directly on the same frequency (no repeater needed). Both stations transmit and receive on the same frequency, taking turns.

5. What is the national calling frequency for VHF (2-meter) FM simplex?

Answer: 146.52 MHz

146.52 MHz is the designated VHF simplex calling frequency in North America. It's used to make initial contact with other stations.

Frequencies and Bands

6. What frequency range is in the VHF portion of the amateur radio spectrum?

Answer: 30 - 300 MHz

VHF stands for Very High Frequency, which spans 30-300 MHz. The 2-meter band (144-148 MHz) is a popular VHF band for Technicians.

7. What does a positive (+) offset mean on a repeater frequency?

Answer: Transmit 600 kHz higher on 2m (or 5 MHz higher on 70cm)

A plus (+) offset means you transmit on a frequency higher than the repeater's receive frequency. On 2 meters it's +600 kHz, on 70cm it's +5 MHz.

8. Which band is most popular for Technician repeater operations?

Answer: 2-meter (144-148 MHz)

The 2-meter band is by far the most popular VHF band for amateur radio, with extensive repeater coverage in most populated areas.

Electrical Principles

9. What is Ohm's Law?

Answer: V = I × R (or I = V/R or R = V/I)

Ohm's Law states that voltage equals current times resistance. This is the fundamental formula in electronics.

10. A circuit has 12 volts and 4 amperes. What is the resistance?

Answer: 3 ohms

Using Ohm's Law: R = V ÷ I = 12 ÷ 4 = 3 ohms. Always check your units (volts, amps, ohms).

11. How is power calculated in electrical circuits?

Answer: P = V × I (Watts)

Power equals voltage times current, measured in Watts. A 12-volt transmitter drawing 10 amps produces 120 watts of power.

12. What are the three primary electrical quantities?

Answer: Voltage, Current, and Resistance

These three quantities (V, I, R) are fundamental to understanding electricity and are related by Ohm's Law.

Components and Circuits

13. What do the color bands on a resistor indicate?

Answer: Resistance value and tolerance

The colored bands represent the resistance value (in ohms) and tolerance (accuracy). Memorize the color code!

14. What is the function of a capacitor?

Answer: Store electrical energy and block DC while passing AC

Capacitors store charge and are useful for filtering, coupling, and tuning circuits. They pass AC but block DC.

15. What does an inductor do in an AC circuit?

Answer: Opposes changes in current and passes DC

Inductors (coils) create a magnetic field and oppose AC signals while passing DC. Used in filters and tuning circuits.

16. What is a diode used for?

Answer: Converts AC to DC (rectification) or acts as a one-way valve for current

Diodes allow current to flow in only one direction, making them useful for rectifiers and various circuit applications.

Radio Propagation

17. What is the primary propagation mode for VHF/UHF frequencies?

Answer: Line-of-sight

VHF and UHF signals travel in straight lines (line-of-sight). They don't reflect off the ionosphere like HF signals do.

18. What is a skip zone?

Answer: An area where a signal cannot be received

The skip zone is the area beyond the ground wave range but too close to receive the skywave signal. It occurs with HF propagation.

19. What factor most affects radio wave propagation at VHF/UHF?

Answer: Terrain and antenna height

With line-of-sight propagation, terrain and antenna height are critical. A higher antenna extends the range significantly.

Antennas

20. What is the most common Technician antenna?

Answer: Dipole antenna

The dipole is half-wavelength long, simple to build, and provides good omnidirectional performance.

21. Calculate the length of a half-wave dipole antenna for 146 MHz.

Answer: About 3.2 feet (38 inches)

Using the formula: 468 ÷ frequency (MHz) = 468 ÷ 146 = 3.2 feet. This is the 2-meter band.

22. What is antenna gain?

Answer: The amplification of signal compared to a reference antenna

Gain is measured in dB or dBi. A directional antenna focuses energy in one direction, increasing gain in that direction while reducing it in others.

23. What is the characteristic impedance of coaxial cable?

Answer: Typically 50 ohms or 75 ohms

Most amateur equipment uses 50-ohm coaxial cable. Matching impedance prevents reflections and power loss.

Station Equipment

24. What is a transceiver?

Answer: A combined transmitter and receiver

Most modern amateur radios are transceivers that both transmit and receive, often using the same antenna for both.

25. What is the typical operating voltage for amateur transceivers?

Answer: 13.8 volts DC

Most portable and mobile amateur radios operate from 12-13.8V DC. Base stations may use higher voltages or AC with conversion.

26. What is a dummy load used for?

Answer: To test transmitter without radiating signals

A dummy load is a 50-ohm resistor that safely absorbs transmitter power. Always use one when testing equipment to avoid unintended on-air transmissions.

Safety

27. What is the FCC limit for RF exposure in an occupational setting?

Answer: Depends on frequency; at 146 MHz it's 5 mW/cm²

Occupational exposure limits are higher than general population limits. You must comply with RF safety regulations.

28. What should you do before working on a power supply?

Answer: Disconnect power and discharge capacitors

Always unplug equipment and discharge all capacitors with an insulated tool. Even when powered down, capacitors can hold dangerous charge.

29. When should you NOT transmit on the air?

Answer: During testing and tuning; always use a dummy load

Testing with a dummy load prevents interference to other operators and unintended radiation. Only transmit on-air when necessary and proper.

30. What does SWR stand for and what does it measure?

Answer: Standing Wave Ratio - measures how well impedances are matched

A low SWR (close to 1:1) indicates good impedance matching. High SWR means reflections and power loss. Ideal is 1:1, acceptable is under 2:1.

Additional Practice Questions

31. What is CTCSS in amateur radio?

Answer: Continuous Tone Coded Squelch System

CTCSS is an inaudible tone added to your transmission that opens repeater squelch. Many repeaters require specific CTCSS tones for access.

32. What is a "negative offset" on a repeater?

Answer: Transmit 600 kHz lower on 2m (or 5 MHz lower on 70cm)

A minus (-) offset means you transmit on a frequency lower than the repeater's output frequency. Configuration is automatic on most transceivers.

33. What frequency calculation shows the relationship between frequency and wavelength?

Answer: Wavelength (meters) = 300 ÷ Frequency (MHz)

This simplified formula lets you quickly calculate wavelength. The 2-meter band is 144-148 MHz because the wavelength is about 2 meters.

34. What is the most common cause of high SWR?

Answer: Antenna impedance mismatch or antenna damage

If your SWR is high, check the antenna for damage, loose connections, or that it's cut to the right length for the frequency.

35. What are the three elementary particles related to electricity?

Answer: Proton (positive), Neutron (neutral), Electron (negative)

These three particles make up atoms. Electron flow (from negative to positive externally) creates electric current.