Ham Radio Extra Class Exam — Questions and Answers

Question 1: What is a 'roundtable' in amateur radio operating practice?

An informal contact where three or more stations take turns transmitting in rotation (Correct answer)
An antenna gain measurement technique using multiple receive points
A circular antenna array configuration for omnidirectional gain
A formal conference call between club officers

Correct answer: An informal contact where three or more stations take turns transmitting in rotation

A roundtable is an informal group conversation where three or more stations take turns transmitting in sequence, each waiting for the previous station to finish.

Question 2: What is the power factor of a circuit with a phase angle of 60 degrees?

0.866
0.707
0.5 (Correct answer)
1.0

Correct answer: 0.5

Power factor equals the cosine of the phase angle, and cos(60 degrees) is 0.5.

Question 3: What is the function of a mixer stage in a superheterodyne receiver?

To amplify weak RF signals before detection
To select between multiple antenna inputs
To combine the RF signal with the local oscillator to produce an intermediate frequency (Correct answer)
To demodulate the audio from the received signal

Correct answer: To combine the RF signal with the local oscillator to produce an intermediate frequency

The mixer multiplies the incoming RF signal with the local oscillator signal to produce sum and difference frequencies, with the difference typically used as the intermediate frequency (IF).

Question 4: What is the function of a bypass capacitor placed across the emitter resistor in a common-emitter amplifier?

To increase AC voltage gain by shorting the emitter resistor at signal frequencies (Correct answer)
To stabilize the DC bias point of the transistor
To prevent thermal runaway of the transistor
To filter out power supply noise from the circuit

Correct answer: To increase AC voltage gain by shorting the emitter resistor at signal frequencies

The bypass capacitor provides a low-impedance path for AC signals around the emitter resistor, removing the negative feedback that reduces gain at signal frequencies.

Question 5: What is the self-resonant frequency of an antenna primarily determined by?

The physical length of the antenna relative to the wavelength (Correct answer)
The feedpoint impedance
The type of coaxial cable used
The antenna's radiation resistance

Correct answer: The physical length of the antenna relative to the wavelength

An antenna's self-resonant frequency is primarily determined by its physical length, which must be an electrical multiple of the operating wavelength.

Question 6: In terms of feed-point impedance, how does a folded dipole differ from a standard half-wave dipole?

The folded dipole has approximately 300 ohms impedance versus about 73 ohms for a standard dipole (Correct answer)
The folded dipole's impedance depends entirely on wire gauge
The folded dipole has 50 ohms versus 73 ohms for a standard dipole
Both have the same feed-point impedance

Correct answer: The folded dipole has approximately 300 ohms impedance versus about 73 ohms for a standard dipole

A folded dipole has approximately 300 ohms feed-point impedance, which is about four times that of a standard half-wave dipole, making it a natural match for 300-ohm twinlead.

Question 7: What condition causes an amplifier to produce intermodulation distortion products at frequencies 2f1−f2 and 2f2−f1?

Excessive forward bias
Impedance mismatch at the input
Linear operation with high gain
Third-order nonlinearity in the active device (Correct answer)

Correct answer: Third-order nonlinearity in the active device

Third-order nonlinearity generates intermodulation products that fall close to the original frequencies, making them difficult to filter.

Question 8: What document serves as the primary reference for FCC rules governing amateur radio in the United States?

The ITU Radio Regulations
The National Electrical Code
The ARRL Handbook
Title 47 CFR Part 97 (Correct answer)

Correct answer: Title 47 CFR Part 97

Title 47 of the Code of Federal Regulations, Part 97, contains all FCC rules governing the Amateur Radio Service in the US.

Question 9: What does the slew rate of an operational amplifier specify?

The common-mode rejection ratio at high frequencies
The input offset voltage drift with temperature
The maximum DC gain before saturation
The maximum rate of change of the output voltage in V/µs (Correct answer)

Correct answer: The maximum rate of change of the output voltage in V/µs

Slew rate is the maximum speed at which an op-amp's output voltage can change, expressed in volts per microsecond.

Question 10: Which FCC rule governs the prohibition against broadcasting by amateur stations?

Section 97.113 (Correct answer)
Section 97.303
Section 97.111
Section 97.5

Correct answer: Section 97.113

Section 97.113 lists prohibited transmissions for amateur stations, including broadcasting.

Question 11: What is the purpose of a balun at the feed point of a dipole antenna fed with coaxial cable?

To increase the gain of the antenna by 3 dB
To prevent common-mode current on the coax shield (Correct answer)
To filter harmonics before they reach the antenna
To match 50-ohm coax to 300-ohm feed line

Correct answer: To prevent common-mode current on the coax shield

A balun prevents unwanted common-mode currents from flowing on the outside of the coax shield, which can distort the antenna pattern.

Question 12: What is the purpose of a Smith chart in amateur radio?

To determine the legal power limits for Extra class operators
To map propagation paths across the ionosphere
To graphically represent complex impedance and solve transmission line problems (Correct answer)
To calculate antenna gain in dBi

Correct answer: To graphically represent complex impedance and solve transmission line problems

A Smith chart is a graphical tool used to represent complex impedance and admittance, making it easier to solve transmission line matching problems.

Question 13: What is a Beverage antenna used for primarily?

Portable direction finding at higher HF frequencies
Directional transmitting for low HF bands
Portable direction finding at lower HF frequencies
Directional receiving for low HF bands (Correct answer)

Correct answer: Directional receiving for low HF bands

A Beverage antenna is a long, low, directional wire antenna primarily used for receiving signals on the low HF bands (e.g., 160 and 80 meters). Its design provides excellent directivity and noise rejection, making it highly effective for weak signal reception from a specific direction, which is crucial for long-distance (DX) listening on these bands. It is not typically used for transmitting due to its low efficiency and high SWR characteristics.

Question 14: What is the principal advantage of using OFDM (Orthogonal Frequency-Division Multiplexing) in digital HF communications?

It is highly resistant to multipath fading and selective fading (Correct answer)
It eliminates the need for synchronization
It uses less bandwidth than single-carrier PSK
It requires no forward error correction

Correct answer: It is highly resistant to multipath fading and selective fading

OFDM spreads data across many narrow subcarriers that are orthogonal to each other, making the signal robust against multipath and frequency-selective fading common on HF.

Question 15: What happens to the impedance of a transmission line when it is terminated in a purely resistive load equal to its characteristic impedance?

It equals the characteristic impedance at all points (Correct answer)
It drops to zero
It doubles at the source
It becomes purely reactive

Correct answer: It equals the characteristic impedance at all points

A line terminated in its characteristic impedance is a matched line, presenting that same impedance at every point along it.

Question 16: How do the gains for the same antenna expressed in dBi and dBd compare?

dBi gain figures are 2.15 dB lower than dBd gain figures
dBi gain figures are the same as the square root of dBd gain figures multiplied by 2.15
dBi gain figures are the reciprocal of dBd gain figures +2.15 dB
dBi gain figures are 2.15 dB higher than dBd gain figures (Correct answer)

Correct answer: dBi gain figures are 2.15 dB higher than dBd gain figures

Antenna gain expressed in dBi (decibels relative to an isotropic radiator) uses a theoretical isotropic antenna as the reference, which radiates equally in all directions. In contrast, dBd (decibels relative to a dipole) uses a half-wave dipole antenna as the reference. A half-wave dipole inherently has a gain of 2.15 dB compared to an isotropic radiator, meaning dBi gain figures will always be 2.15 dB higher than dBd gain figures for the same antenna.

Question 17: In a Class AB push-pull amplifier, what is the purpose of the slight forward bias applied to both transistors?

To reduce crossover distortion (Correct answer)
To improve frequency response
To increase power output
To lower the input impedance

Correct answer: To reduce crossover distortion

The slight forward bias in Class AB operation keeps both transistors conducting near the zero-crossing point, eliminating the crossover distortion seen in pure Class B designs.

Question 18: What happens to the bandwidth of an FM signal if the deviation is held constant and the modulating frequency is doubled?

The bandwidth increases (Correct answer)
The bandwidth stays the same
The bandwidth decreases
The bandwidth is cut in half

Correct answer: The bandwidth increases

Increasing the modulating frequency while keeping deviation constant increases the occupied bandwidth per Carson's rule.

Question 19: What causes long-path propagation on HF frequencies?

Signals refracting around Earth the long way via multiple ionospheric hops (Correct answer)
Tropospheric ducting over ocean paths
Ground wave following the curvature of the Earth
Signals traveling the short great-circle path between two stations

Correct answer: Signals refracting around Earth the long way via multiple ionospheric hops

Long-path propagation occurs when signals travel the longer great-circle route around Earth through multiple ionospheric refractions, sometimes providing a stronger path than the short route.

Question 20: What is the minimum age requirement to hold an amateur radio license in the United States?

18 years old
16 years old
14 years old
No minimum age (Correct answer)

Correct answer: No minimum age

There is no minimum age requirement to obtain an amateur radio license in the United States.

Question 21: Which antenna type produces a circularly polarized signal?

A collinear vertical array
A crossed-Yagi fed 90 degrees out of phase (Correct answer)
A ground-plane antenna with drooping radials
A half-wave dipole mounted at an angle

Correct answer: A crossed-Yagi fed 90 degrees out of phase

A crossed-Yagi with quadrature (90-degree) phasing between elements produces circular polarization, commonly used for satellite work.

Question 22: Under FCC Part 97, which of the following is a legitimate third-party traffic restriction?

Third-party traffic is banned with countries that have no third-party agreement with the US (Correct answer)
Third-party traffic is allowed only on 2 meters and above
Third-party traffic is prohibited on all HF bands
Third-party messages may only be sent using CW

Correct answer: Third-party traffic is banned with countries that have no third-party agreement with the US

FCC rules prohibit third-party international traffic with countries that do not have a third-party agreement with the United States.

Question 23: What is the effect of adding a director element to a Yagi antenna in front of the driven element?

It rotates the polarization 90 degrees
It increases the front-to-back ratio and forward gain (Correct answer)
It broadens the antenna bandwidth
It raises the feed point impedance

Correct answer: It increases the front-to-back ratio and forward gain

A director, being slightly shorter than the driven element, re-radiates energy forward, increasing forward gain and front-to-back ratio.

Question 24: What is transequatorial propagation (TEP)?

Tropospheric ducting that occurs only in equatorial regions
E-layer skip between stations on the same side of the equator
Propagation along the equator using ground wave
A mode where signals cross the geomagnetic equator via the F layer at VHF frequencies (Correct answer)

Correct answer: A mode where signals cross the geomagnetic equator via the F layer at VHF frequencies

TEP allows VHF signals to travel across the geomagnetic equator by refracting through tilted F-layer ionization, linking stations in opposite hemispheres.

Question 25: What is the approximate velocity factor of standard RG-213 coaxial cable?

0.80
0.66 (Correct answer)
0.95
0.50

Correct answer: 0.66

RG-213 coaxial cable with a solid polyethylene dielectric has a velocity factor of approximately 0.66.

Question 26: A radio amateur is attempting a long-distance contact on a lower HF band (e.g., 80 meters) and notices a significant signal enhancement for a short period around sunrise and sunset, but only when the path is aligned with the terminator. What is this mode of propagation called?

Backscatter
Gray-line propagation (Correct answer)
Transequatorial propagation
Sporadic E-skip

Correct answer: Gray-line propagation

Gray-line propagation occurs along the terminator, the line separating daylight and darkness on Earth. During this time, the D-layer, which absorbs lower-frequency HF signals, rapidly disappears or has not yet formed, while the F-layer remains ionized and capable of refracting signals. This combination of low absorption and available refraction creates a brief window for excellent long-distance communication, especially on the lower HF bands.

Question 27: What is the primary advantage of a Chebyshev low-pass filter design compared to a Butterworth design of the same order?

Lower component count
Steeper rolloff in the stopband (Correct answer)
Flatter passband response
Higher power handling

Correct answer: Steeper rolloff in the stopband

Chebyshev filters achieve a steeper transition from passband to stopband than Butterworth filters of the same order, at the cost of passband ripple.

Question 28: What advantage does a log-periodic amplifier offer compared to a single-tuned amplifier in a wideband receiver?

Relatively constant gain over a wide frequency range (Correct answer)
Better image rejection without a preselector
Lower noise figure at VHF frequencies
Higher gain at a single specific frequency

Correct answer: Relatively constant gain over a wide frequency range

Log-periodic amplifier designs provide approximately uniform gain across a wide bandwidth, making them suitable for broadband receiver front ends.

Question 29: In direct digital synthesis (DDS), what determines the output frequency of the synthesizer?

The crystal resonator temperature coefficient
The phase increment value loaded into the phase accumulator register (Correct answer)
The analog voltage applied to the VCO input
The divide ratio of the output prescaler

Correct answer: The phase increment value loaded into the phase accumulator register

A DDS generates a frequency by repeatedly adding a phase increment to a phase accumulator; larger increments produce higher frequencies from the same reference clock.

Question 30: What is the primary advantage of using a direct digital synthesizer (DDS) as a VFO?

Reduced current consumption compared to crystal oscillators
Higher output power than analog oscillators
Elimination of all spurious signals
Extremely fine frequency resolution and fast switching speed (Correct answer)

Correct answer: Extremely fine frequency resolution and fast switching speed

DDS provides very fine frequency steps and can switch frequencies in microseconds, making it ideal for modern transceivers.

Question 31: What is the purpose of a cascode configuration in an RF preamplifier?

To provide automatic gain control
To eliminate the need for an output matching network
To increase the output power capability
To reduce the Miller effect and improve high-frequency gain (Correct answer)

Correct answer: To reduce the Miller effect and improve high-frequency gain

The cascode configuration stacks a common-emitter stage with a common-base stage, which drastically reduces Miller capacitance and improves gain-bandwidth product.

Question 32: Which type of diode is specifically designed to operate in the reverse-breakdown region for voltage regulation?

Schottky diode
PIN diode
Zener diode (Correct answer)
Tunnel diode

Correct answer: Zener diode

Zener diodes are doped to have a precise, stable reverse breakdown voltage used for voltage regulation.

Question 33: A buffer amplifier is placed between a VFO and subsequent amplifier stages primarily to:

Convert AM to FM
Boost output power to legal limit
Filter harmonic content from the carrier
Isolate the oscillator from load variations that could cause frequency pulling (Correct answer)

Correct answer: Isolate the oscillator from load variations that could cause frequency pulling

Buffer amplifiers present a constant, high-impedance load to the oscillator, preventing output loading from shifting the oscillation frequency.

Question 34: Which of the following best sums up how a speech processor affects a phone signal being transmitted with just one sideband?

It increases average power (Correct answer)
It increases peak power
It reduces intermodulation distortion
It reduces harmonic distortion

Correct answer: It increases average power

A speech processor in a single sideband (SSB) transmitter is designed to increase the average power of the transmitted signal without exceeding the peak envelope power (PEP) limits. It achieves this by compressing the dynamic range of the audio signal, making the quieter parts louder relative to the peaks. This results in a more consistent and 'punchier' signal, improving readability at the receiving end, especially under marginal propagation conditions.

Question 35: What type of amateur license examination is administered by a Volunteer Examiner Coordinator (VEC)?

Only Extra class exams
Only Technician class exams
Technician, General, and Amateur Extra class exams (Correct answer)
Only upgrade exams from General to Extra

Correct answer: Technician, General, and Amateur Extra class exams

VECs coordinate the administration of all three classes of amateur radio exams: Technician, General, and Amateur Extra.

Question 36: Which of the following best describes the radiation pattern of a two-element Yagi antenna?

An omnidirectional pattern in the horizontal plane
Equal radiation in all directions including vertical
A cardioid pattern with maximum radiation toward the director (Correct answer)
A figure-eight pattern broadside to the elements

Correct answer: A cardioid pattern with maximum radiation toward the director

A two-element Yagi produces a cardioid-shaped pattern with the main lobe directed from the reflector toward the director.

Question 37: What is the approximate gain of a five-element Yagi antenna over a dipole?

Approximately 3 dBd
Approximately 1 dBd
Approximately 20 dBd
Approximately 10 dBd (Correct answer)

Correct answer: Approximately 10 dBd

A well-designed five-element Yagi typically provides about 10 dBd of gain over a reference dipole.

Question 38: What is the feed point impedance of a folded dipole antenna compared to a standard half-wave dipole?

Eight times higher (about 584 ohms)
The same (73 ohms)
Half (about 36 ohms)
Four times higher (about 292 ohms) (Correct answer)

Correct answer: Four times higher (about 292 ohms)

A folded dipole has approximately four times the impedance of a standard dipole, making it approximately 300 ohms — ideal for 300-ohm twin-lead.

Question 39: In a PSK31 signal, what type of modulation shift represents a binary zero?

A frequency shift of 31 Hz
A 180-degree phase shift (Correct answer)
No phase shift
A 90-degree phase shift

Correct answer: A 180-degree phase shift

In BPSK31, a binary zero is represented by a 180-degree phase reversal of the carrier signal.

Question 40: What is the radiation pattern of an isotropic antenna?

A cardioid pattern with a defined null
A figure-eight pattern in the horizontal plane
A toroidal pattern with a null off the ends
A perfect sphere — equal radiation in all directions (Correct answer)

Correct answer: A perfect sphere — equal radiation in all directions

An isotropic antenna is a theoretical point source that radiates equally in all directions, forming a perfect sphere.

Question 41: Under what circumstances may an amateur station automatically retransmit the signals of other amateur stations?

Never under any circumstances
When operating as a repeater station (Correct answer)
When the originating station gives verbal permission
Only during declared emergencies

Correct answer: When operating as a repeater station

Amateur stations functioning as auxiliary or repeater stations may automatically retransmit other amateur signals as permitted under FCC Part 97.

Question 42: What is the maximum symbol rate permitted for RTTY or data emission on the 20-meter band for Extra class licensees?

1200 baud
56 kilobaud
19.6 kilobaud
300 baud (Correct answer)

Correct answer: 300 baud

On the 20-meter band, the maximum symbol rate for RTTY and data emissions is 300 baud per FCC Part 97.

Question 43: What is the approximate gain of a five-element Yagi-Uda antenna over a dipole?

About 3 dBd
About 0 dBd
About 20 dBd
About 10 dBd (Correct answer)

Correct answer: About 10 dBd

A well-designed five-element Yagi typically provides roughly 10 dBd of gain, combining the effects of one reflector and three directors.

Question 44: If a 100-foot length of coaxial cable with a velocity factor of 0.66 is used to construct a quarter-wave matching stub at 14.1 MHz, what is its approximate physical length?

The conductivity of the center conductor and shield
The overall diameter of the cable
The frequency of the signal being transmitted
The type of dielectric material used between the conductors (Correct answer)

Correct answer: The type of dielectric material used between the conductors

The velocity factor (VF) of a coaxial cable is the ratio of the speed of signal propagation in the cable to the speed of light in a vacuum. This speed is primarily determined by the dielectric constant of the insulating material separating the center conductor and the shield. Materials like foam polyethylene have a higher velocity factor (e.g., 0.82) than solid polyethylene (e.g., 0.66) because their dielectric constant is lower, allowing the wave to travel faster.

Question 45: Which transmission line type has the lowest loss per unit length at VHF frequencies?

RG-8 coaxial cable
Open-wire ladder line (Correct answer)
RG-58 coaxial cable
Hardline coaxial cable

Correct answer: Open-wire ladder line

Open-wire ladder line has the lowest loss per unit length because its low-density dielectric minimizes dielectric losses, especially at VHF.

Question 46: What are 'birdies' in a receiver and what causes them?

External interference produced by nearby power lines at audio frequencies
Audio oscillations caused by insufficient decoupling of the audio amplifier
Spurious internal signals caused by intermodulation of oscillator harmonics with other internal signals (Correct answer)
Interference from UHF bird-detection radar systems

Correct answer: Spurious internal signals caused by intermodulation of oscillator harmonics with other internal signals

Birdies are internally generated spurious signals that appear at fixed frequencies in a receiver, caused by mixing of harmonics of the local oscillator with other oscillators or clocks inside the receiver.

Question 47: Which component in a superheterodyne receiver is responsible for rejecting the image frequency?

The IF amplifier
The AGC circuit
The preselector or front-end bandpass filter (Correct answer)
The beat frequency oscillator

Correct answer: The preselector or front-end bandpass filter

The preselector filter ahead of the mixer attenuates the image frequency, which is separated from the desired signal by twice the IF.

Question 48: Which type of amplifier configuration is commonly used in the front end of a receiver to provide gain with minimum added noise?

Class C power amplifier
Push-pull class B audio amplifier
Class D switching amplifier
Low-noise amplifier (LNA) using a GaAs FET or similar low-noise device (Correct answer)

Correct answer: Low-noise amplifier (LNA) using a GaAs FET or similar low-noise device

LNAs using GaAs FETs or modern low-noise transistors are designed to add minimal thermal noise while providing useful gain at RF frequencies.

Question 49: Which mode of propagation is responsible for extending 2-meter VHF signals over 1,000 miles or more during periods of stable high-pressure weather systems?

Sporadic E
Meteor scatter
Tropospheric ducting (Correct answer)
Transequatorial propagation

Correct answer: Tropospheric ducting

Tropospheric ducting occurs when a temperature inversion in the lower atmosphere traps VHF/UHF signals, acting like a waveguide that can carry signals for hundreds to thousands of miles. It is most common during stable, warm, high-pressure conditions.

Question 50: What is the function of a balun at a dipole feed point when coaxial cable is used?

To reduce SWR on the transmission line
To match impedance to 300 ohms
To prevent common-mode current on the coax shield (Correct answer)
To increase antenna gain

Correct answer: To prevent common-mode current on the coax shield

A balun suppresses common-mode (shield) currents that would otherwise cause the coax to radiate and distort the antenna pattern.

Question 51: What is the characteristic impedance of a lossless transmission line with a distributed inductance of 250 nanohenries per meter and a distributed capacitance of 100 picofarads per meter?

25 ohms
100 ohms
50 ohms (Correct answer)
75 ohms

Correct answer: 50 ohms

Z₀ = √(L/C) = √(250×10⁻⁹/100×10⁻¹²) = √2500 = 50 ohms.

Question 52: Which component in a switching power supply controls the duty cycle to regulate output voltage?

The output filter inductor
The PWM controller IC (Correct answer)
The rectifier diode
The input capacitor bank

Correct answer: The PWM controller IC

The PWM (pulse-width modulation) controller IC compares the output voltage to a reference and adjusts the duty cycle of the switching transistor accordingly.

Ham Radio Extra Class Exam

The FCC Extra Class exam is the highest amateur radio license, covering all amateur bands.

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40 min

Time Limit

74%

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