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Key Facts: UK Amateur Radio Full Licence Exam Exam
58 Qs
Exam Questions
60% (35/58 marks)
Passing Score
£45.00
Exam Fee
Master the 58-question RSGB Full Licence exam with 100 free practice questions covering advanced electronics, DSP, antenna synthesis, and ITU rules.
Sample UK Amateur Radio Full Licence Exam Practice Questions
Try these sample questions to review concepts for the UK Amateur Radio Full Licence Exam exam. Each question includes a detailed explanation. Start the interactive quiz above for the full 100+ question experience with AI tutoring.
1What is the conduction angle of a transistor operating as a Class A linear RF amplifier?
A.360 degrees (the transistor conducts throughout the entire RF cycle)
B.180 degrees (the transistor conducts for half of the RF cycle)
C.Between 180 and 360 degrees
D.Less than 180 degrees (short pulses)
Explanation: In a Class A RF amplifier, the transistor is biased in the middle of its active linear region so that current flows through the device for the entire 360 degrees of the input AC cycle. This provides maximum linearity and lowest distortion, though theoretical efficiency is limited to 50% (or 25% for series-fed loads).
2Why is a Class C amplifier unsuitable for amplifying single-sideband (SSB) voice signals?
A.It has low RF output power capabilities
B.It is non-linear and causes severe intermodulation distortion of amplitude-varying signals
C.It exhibits negative input impedance at high frequencies
D.It requires a dual symmetrical power supply
Explanation: Class C amplifiers conduct for less than 180 degrees of the input cycle, making them non-linear. SSB signals contain both amplitude and phase modulation; passing an amplitude-varying signal through a non-linear Class C stage clips the signal envelope, producing severe intermodulation distortion (splatter). Linear amplifiers (Class A or Class AB) are required for SSB.
3What is the voltage gain ($A_v$) formula for an ideal inverting operational amplifier circuit with feedback resistor $R_f$ and input resistor $R_{in}$?
A.A_v = 1 + (R_f / R_{in})
B.A_v = R_{in} / R_f
C.A_v = -R_f / R_{in}
D.A_v = -(R_{in} / R_f)
Explanation: For an ideal inverting operational amplifier, negative feedback maintains a virtual ground at the inverting input. The current flowing through $R_{in}$ is $V_{in} / R_{in}$, which equals the current through $R_f$ ($ -V_{out} / R_f$). Solving for voltage gain yields $A_v = V_{out} / V_{in} = -R_f / R_{in}$.
4In the equivalent electrical circuit of a quartz crystal unit, what condition occurs at the series resonant frequency ($f_s$)?
A.The inductive reactance of the motional arm equals the capacitive reactance of the motional arm, yielding minimum series impedance
B.The total crystal impedance reaches its maximum value
C.The parallel shunt capacitance $C_0$ dominates, blocking all AC current
D.The Q factor of the crystal drops to zero
Explanation: A quartz crystal's motional branch consists of motional inductance ($L_m$), motional capacitance ($C_m$), and motional resistance ($R_m$) in series. At series resonance ($f_s = 1 / [2\pi \sqrt{L_m C_m}]$), $X_{Lm} = X_{Cm}$, canceling out and leaving only the very low motional resistance $R_m$, which gives minimum impedance.
5Which combination of reactive components forms the feedback network of a classic Colpitts LC oscillator?
A.A tapped inductor connected across a single tuning capacitor
B.A quartz crystal in series with a variable inductor
C.A resistor-capacitor phase-shift ladder network
D.A capacitive voltage divider (two series capacitors) connected in parallel with an inductor
Explanation: A Colpitts oscillator uses a capacitive voltage divider (two capacitors connected in series across a main inductor) to tap off a fraction of the tank circuit RF voltage and feed it back in proper phase to the active device's input (base/gate).
6How does a PIN diode behave when operated at high radio frequencies (VHF/UHF)?
A.As a conventional fast-switching diode with a constant 0.7V forward voltage drop
B.As a variable RF resistor whose resistance is inversely proportional to the applied DC bias current
C.As a voltage-controlled variable capacitor (varactor)
D.As a high-efficiency power rectifier
Explanation: At RF frequencies above the carrier lifetime threshold of its intrinsic (I) layer, a PIN diode does not rectify the RF voltage. Instead, its intrinsic layer stores charge, causing it to act as a current-controlled RF resistor. Increasing DC forward bias lowers its RF resistance (down to $<1 \ \Omega$), allowing it to serve as a low-distortion RF switch or variable attenuator.
7What is the primary function of the phase detector stage in a Phase-Locked Loop (PLL) frequency synthesizer?
A.To compare the phase/frequency of the divided VCO output with a stable reference signal and produce an error signal
B.To amplify the high-frequency RF output from the Voltage Controlled Oscillator (VCO)
C.To convert an analog audio signal into a pulse-width modulated control voltage
D.To filter out high-order harmonics from the synthesizer output
Explanation: The phase detector (or phase-frequency detector) compares the phase of a reference oscillator signal (usually crystal-derived) with the output of the frequency-divided VCO. It generates an error voltage proportional to the phase difference, which passes through a loop filter to steer the VCO until both signals are locked in phase.
8Why do Junction Field-Effect Transistors (JFETs) and MOSFETs exhibit significantly higher input impedance than Bipolar Junction Transistors (BJTs)?
A.They utilize heavy minority carrier injection across a forward-biased PN junction
B.Their control terminal (gate) is insulated or reverse-biased, resulting in minimal DC gate current
C.They operate exclusively at negative power supply voltages
D.They possess a lower transconductance ($g_m$) than BJTs
Explanation: In a JFET, the gate-channel PN junction is kept reverse-biased. In a MOSFET, the metal/polysilicon gate is physically insulated from the channel by a thin oxide layer ($SiO_2$). Both mechanisms prevent DC current flow into the gate, giving input impedances in the megaohms (JFET) or gigaohms (MOSFET) range, compared to kilohms for a forward-biased BJT base-emitter junction.
9Which response characteristic distinguishes a Chebyshev active filter from a Butterworth filter of the same order?
A.Chebyshev filters have a completely flat amplitude response in the passband with no ripple
B.Chebyshev filters provide a steeper cutoff slope (transition rate) at the expense of passband ripple
C.Chebyshev filters exhibit a perfectly linear phase response across the entire stopband
D.Chebyshev filters require no inductors or capacitors in passive implementations
Explanation: Chebyshev filters trade passband flatness for a sharper transition roll-off rate around the cutoff frequency compared to Butterworth filters of the same order. This introduces equal-amplitude ripple in the passband (Type I) or stopband (Type II). Butterworth filters are maximally flat in the passband.
10In a Class D switching RF power amplifier, what keeps power dissipation in the active switching transistors low?
A.The transistors operate continuously in their linear active region with low collector current
B.The transistors switch rapidly between fully OFF (zero current) and fully ON (near-zero voltage drop)
C.Negative feedback forces the drain voltage and drain current to remain in phase at all times
D.High value emitter resistors limit the total DC current drawn from the power supply
Explanation: Power dissipation in a transistor is $P = V imes I$. In a Class D switching amplifier, the transistors act as binary switches: when OFF, current $I = 0$, so $P = 0$; when ON (saturated), voltage $V \approx 0$, so $P \approx 0$. Because the product $V imes I$ is near zero in both states, theoretical efficiency approaches 100%, requiring a low-pass output filter to extract the fundamental RF sine wave.
About the UK Amateur Radio Full Licence Exam Exam
The UK Amateur Radio Full Licence exam (HAREC standard) grants full amateur privileges including higher power output (up to 400W) and international reciprocal licensing.
Exam sponsor: Radio Society of Great Britain (RSGB). The requirements and fees below concern the certification or admission exam, separate from our free practice resources.
Questions
58 questions
Time Limit
120 minutes
Passing Score
60% (35/58 marks)
Fees, eligibility, and exam policies can change. Confirm them with the exam sponsor before applying or paying.
Official sources
Our practice resources: topics covered
We aim to reflect publicly available exam outlines and topic information in our study resources. Coverage, format, and difficulty may differ from the actual exam, and we cannot guarantee that every detail is accurate or current. Confirm exam requirements, fees, and policies with the official exam sponsor.
30%
Advanced Circuit Theory & DSP
Digital signal processing, active filters, semiconductor physics, and RF design.
25%
Transmitter & Receiver Design
Direct sampling receivers, power amplifiers, intermodulation, and phase noise.
25%
Antennas, Matching & Propagation
Impedance matching, Smith charts, antenna modeling, and space weather.
20%
International Regulations & Safety
ITU radio regulations, Ofcom full licence terms, and ICNIRP RF safety limits.
Preparing for the UK Amateur Radio Full Licence Exam Exam
What You Need to Know
- Passing score: 60% (35/58 marks)
- Exam length: 58 questions
- Time limit: 120 minutes
- Exam / certification fees: £45.00 Official sources
Using Our Practice Resources
- Work through all 100 available questions
- Review every answer and explanation
- Track weak areas and revisit them
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UK Amateur Radio Full Licence Exam: Suggested Study Strategy
1Review all official Radio Society of Great Britain (RSGB) syllabus domain weightings and key terms before testing.
2Practice timed mock questions to build pace for the 120 minutes exam limit.
3Study answer explanations carefully to understand why incorrect distractors are wrong.
Frequently Asked Questions
How many questions are on the official Full Licence exam?
The official Full Licence exam consists of 58 questions to be completed within 120 minutes.
What is the passing score for the Full Licence exam?
The passing score for the Full Licence exam is 60% (35/58 marks).
How much does the Full Licence exam cost?
The official exam fee for the Full Licence is £45.00.