Full Sample Questions

Three questions from each section of the Full syllabus. Pick an answer to see whether you're right, how everyone else did, and why.

Full exam guide

1 Licensing conditions and station identification

On the 70cm band (430-432 MHz), the Full licence power limit is 40 W ERP. If your antenna has a gain of 6 dBd and the feeder loss is 2 dB, what is the maximum transmitter output power?

  1. 40 W
  2. 100 W
  3. 16 W
  4. 10 W

Answer: C, 16 W. Schedule 1 Table C gives 40 W ERP at 430-432 MHz. A 6 dBd gain is x4, so 40 W ERP needs 10 W at the antenna. Adding back the 2 dB feeder loss (about x1.6) gives roughly 16 W from the transmitter.

What is the distinction between codes/abbreviations and encryption in amateur radio?

  1. Q-codes are permitted; encryption to obscure meaning is generally banned
  2. Q-codes are permitted; encryption is permitted if both stations agree to it
  3. There is no distinction; Q-codes and encryption are both prohibited
  4. Encryption is allowed on bands above 30 MHz; Q-codes are permitted on all bands

Answer: A, Q-codes are permitted; encryption to obscure meaning is generally banned. Full syllabus 1C1 and licence Condition 6 (clause 19b): abbreviations such as Q-codes are permitted because they are public and carry open meaning. Encryption to obscure the meaning of messages is prohibited, apart from satellite control signals.

What is the role of Ofcom in cases of Undue Interference?

  1. Ofcom advises on complaints but has no power to order changes
  2. Ofcom deals with broadcast interference, not amateur stations
  3. The RSGB investigates complaints and can order station closedown
  4. Ofcom investigates complaints and can require changes or closedown

Answer: D, Ofcom investigates complaints and can require changes or closedown. Ofcom is the regulator. Under Condition 8, an authorised person can require the equipment to be modified, restricted or closed down if it is causing Undue Interference. Full syllabus 1D1.

2 Technical aspects

A transformer has 100 primary turns and 500 secondary turns. If the primary current is 2A, what is the approximate secondary current (assuming an ideal transformer)?

  1. 0.2 A
  2. 0.4 A
  3. 2 A
  4. 10 A

Answer: B, 0.4 A. In an ideal transformer, Is = Ip × Np/Ns = 2 × 100/500 = 0.4 A. The secondary has five times the voltage, so it carries one fifth of the current (Full syllabus 2G1).

A simple LC resonant circuit has a resonant frequency of 10 MHz. If the inductance is doubled while capacitance is halved, what is the new frequency?

  1. 5 MHz
  2. 20 MHz
  3. 10 MHz
  4. 2.5 MHz

Answer: C, 10 MHz. Resonant frequency depends on the product LC. Doubling L and halving C leaves LC unchanged, so the frequency stays at 10 MHz. See Full syllabus 2H1.

What is the purpose of a Zener diode?

  1. To regulate voltage
  2. To emit light
  3. To amplify signals
  4. To rectify AC to DC

Answer: A, To regulate voltage. Full syllabus 2I1: a Zener diode conducts in reverse once the applied voltage exceeds its rated Zener voltage, holding the voltage across it nearly constant. This makes it a simple voltage regulator.

3 Transmitters and receivers

Two strong signals at 10.000 MHz and 10.002 MHz enter a receiver with a third-order intercept point of +20 dBm. What is the frequency of the third-order intermodulation product that appears above the higher of the two input signals?

  1. 10.006 MHz
  2. 9.998 MHz
  3. 10.001 MHz
  4. 10.004 MHz

Answer: D, 10.004 MHz. Third-order products are 2f1 - f2 and 2f2 - f1. With 10.000 and 10.002 MHz, 2f2 - f1 = 20.004 - 10.000 = 10.004 MHz, just above the higher signal. Full syllabus 3H3.

One advantage of a high Intermediate Frequency (IF) is:

  1. Lower power consumption
  2. Better Selectivity
  3. Better Image Rejection
  4. Easier to build

Answer: C, Better Image Rejection. The image frequency lies twice the IF away from the wanted signal. A high IF moves it further away, so the RF tuned circuits can reject it more easily. Full syllabus 3I3.

Frequency Deviation in FM is proportional to:

  1. The amplitude of the modulating audio signal
  2. The power supply voltage
  3. The carrier frequency
  4. The frequency of the modulating audio signal

Answer: A, The amplitude of the modulating audio signal. Per syllabus 3E1, FM peak deviation is proportional to the amplitude (loudness) of the modulating audio signal. Louder audio produces a greater frequency swing. Audio frequency controls the rate of deviation change, not its magnitude.

4 Feeders and antennas

A 50 Ohm transmission line has a VSWR of 3:1. Approximately what percentage of the forward power is reflected back towards the transmitter?

  1. 25%
  2. 11%
  3. 50%
  4. 36%

Answer: A, 25%. A 3:1 VSWR gives a reflection coefficient of (3-1)/(3+1) = 0.5. Reflected power goes with the square of that, so 0.25, or 25% of the forward power. See Full syllabus 4E1 on SWR and reflected signals.

Using the formula Zo squared = Zin x Zout, what characteristic impedance cable is needed to match 50 ohms to 200 ohms using a quarter-wave transformer?

  1. 150 ohms
  2. 100 ohms
  3. 75 ohms
  4. 125 ohms

Answer: B, 100 ohms. Syllabus 4F2 formula: Zo² = Zin × Zout. Zo = √(50 × 200) = √10000 = 100 Ω. A 100-ohm characteristic-impedance quarter-wave section correctly transforms 50 Ω to 200 Ω at the design frequency.

On a centre-fed half-wave dipole at resonance, the current distribution shows:

  1. Uniform current along the entire length
  2. Maximum current at the ends and minimum at the centre
  3. Maximum current at the centre and minimum at the ends
  4. Current only at the feed point

Answer: C, Maximum current at the centre and minimum at the ends. On a resonant centre-fed half-wave dipole the current is greatest at the centre feed point and falls to a minimum at the open ends. The voltage does the opposite, being low at the centre and high at the ends. This distribution is in Full syllabus 4D2.

5 Propagation

Which of the following is NOT a characteristic of the ionosphere during a Sudden Ionospheric Disturbance (SID)?

  1. HF blackouts, worst on the lower frequencies.
  2. Rapid onset following an X-class solar flare.
  3. Decreased F-layer ionisation aiding reflection.
  4. Increased D-layer absorption on sunlit paths.

Answer: C, Decreased F-layer ionisation aiding reflection.. A flare's X-rays suddenly raise D-layer ionisation, so HF is absorbed on sunlit paths within minutes, worst on the lower frequencies. F-layer reflection is not improved. Full syllabus 5B1 (effects of solar flares).

A "Link Budget" calculation accounts for:

  1. Antenna height and the maximum usable frequency
  2. Transmitter efficiency and power supply current drain
  3. Transmit power, gains and path losses
  4. Receiver selectivity and image rejection

Answer: C, Transmit power, gains and path losses. A link budget adds up the factors that decide the received signal: transmitter power, feeder losses, antenna gains and path loss (spreading and obstruction). This is Full syllabus 5D2.

To work stations via auroral reflection on VHF, antennas should generally be pointed:

  1. Towards the equator, generally southward
  2. Towards the aurora, normally to the north
  3. Straight up, towards the zenith overhead
  4. Directly at the distant station's location

Answer: B, Towards the aurora, normally to the north. Auroral propagation reflects signals from ionised curtains in the aurora, which lie towards the pole. From the UK you point your antenna at the aurora, normally to the north, not at the other station (Full syllabus 5C3).

6 Electromagnetic compatibility

A ferrite ring placed around a coaxial cable will attenuate common-mode currents but not affect the differential-mode (wanted) signal because:

  1. The wanted signal travels on the outside of the braid past the ferrite
  2. The equal and opposite wanted currents cancel their fields in the ferrite
  3. The ferrite is effective at audio frequencies but not at RF
  4. The ferrite shorts the unwanted current to earth through the screen

Answer: B, The equal and opposite wanted currents cancel their fields in the ferrite. In a coax, the wanted signal currents on the inner and screen are equal and opposite, so their magnetic fields cancel in the ferrite and it adds no impedance to them. Common-mode currents flow the same way, so the ferrite impedes them. Full syllabus 6D2.

A TV Masthead Amplifier can be overloaded by:

  1. Ghosting caused by multipath reflections from nearby buildings
  2. Local oscillator radiation from the TV set passing back up the downlead
  3. Strong out-of-band amateur transmissions
  4. Normal levels of digital TV multiplex signals

Answer: C, Strong out-of-band amateur transmissions. Many TV masthead amplifiers are wideband, so strong amateur signals outside the TV band still reach them. That can cause overload, cross-modulation and intermodulation. Full syllabus 6C2.

Imported electronic equipment and toys may not be compliant with relevant EMC regulations. What is the likely consequence?

  1. They may cause interference and be more susceptible to it
  2. They will cause interference only if they contain radio communication facilities
  3. They will have better immunity but cause more interference
  4. They will cause interference but have excellent immunity

Answer: A, They may cause interference and be more susceptible to it. Full syllabus 6B1: imported or home-built equipment and toys may not meet EMC standards, so they can both emit interference and be more susceptible to it from nearby transmissions.

7 Good operating practices and procedures

On the 5 MHz (60m) band, what sideband mode is used for SSB operation?

  1. Upper Sideband (USB)
  2. Lower Sideband (LSB)
  3. SSB is not permitted on 60m
  4. Either sideband depending on the operator

Answer: A, Upper Sideband (USB). The Full band plan notes that on 5 MHz USB is used, and that Upper Sideband is recommended for SSB activity. This differs from the usual LSB below 10 MHz. It comes from syllabus 7B1 and the 5 MHz band plan.

What is the purpose of the CEPT Harmonised Amateur Radio Examination Certificate (HAREC)?

  1. It replaces the UK Full licence for operation within the UK
  2. It certifies that the holder's equipment meets CEPT EMC standards
  3. It is required for HF operation at home in the UK
  4. It helps countries grant reciprocal licences to HAREC holders

Answer: D, It helps countries grant reciprocal licences to HAREC holders. The HAREC shows a holder has reached a harmonised CEPT standard, which helps many countries grant reciprocal licences to UK amateurs holding a HAREC Full licence. See Full syllabus 7H1.

At Full licence level, why is it important to conduct periodic tests to ensure the station is not causing Undue Interference?

  1. Because equipment can degrade and start radiating spurious emissions
  2. Because the licence requires a test report to be sent to Ofcom every five years
  3. Because tests are needed to prove that the licence power limit is not exceeded
  4. Because a new neighbour's equipment must be tested for immunity before it is switched on

Answer: A, Because equipment can degrade and start radiating spurious emissions. Equipment can degrade with age or faults and begin radiating spurious emissions, so a Full licensee should test from time to time to make sure the station is not causing Undue Interference (syllabus 7A8).

8 Safety

A "Clean Earth" for RF purposes should:

  1. Not be confused with the mains PME earth, but PME safety rules must be followed
  2. Be as long as possible so that it couples to a larger area of ground
  3. Be connected to the incoming gas or water pipe without any bonding checks
  4. Be connected to the mains neutral conductor at the socket to give RF currents a return path

Answer: A, Not be confused with the mains PME earth, but PME safety rules must be followed. An RF earth carries RF currents away from the mains earth system, but it is not the same as the PME earth. PME faults can cause fatal shocks or fires, so the RF earth must follow the PME bonding requirements, with any cross-bonding tested and recorded by a professional (Full 8A2).

When operating from a temporary location (e.g. Field Day), you should use:

  1. Several mains adaptors chained together to reach the operating position
  2. Extension reels left fully coiled while carrying the full load
  3. A petrol generator operated inside the operating tent
  4. An RCD (Residual Current Device) on the mains supply

Answer: D, An RCD (Residual Current Device) on the mains supply. Full syllabus 8F4 lists correct fusing and use of RCDs or RCBOs among the precautions for temporary or outdoor operation. An RCD cuts the supply quickly in an earth fault, which matters on damp ground.

During a thunderstorm, the best way to protect your station is to:

  1. Switch off at the front panel
  2. Operate only on VHF/UHF, where lightning has less effect
  3. Disconnect all antenna feeders and mains plugs
  4. Connect everything to earth

Answer: C, Disconnect all antenna feeders and mains plugs. Full syllabus 8E1 says little can be done against a direct strike, but disconnecting antenna feeders from the equipment (and mains) reduces the risk. This physically breaks the path for surges and static into the shack.

9 Measurements and construction

To shield a sensitive receiver room from an external RF field, you install a Faraday cage. If the shielding material has an attenuation of 40 dB, by what factor is the internal field strength reduced?

  1. 1000 times
  2. 10 times
  3. 100 times
  4. 40 times

Answer: C, 100 times. Field strength behaves like a voltage, so dB = 20 log(ratio). 40 dB gives a ratio of 100, so the internal field is 100 times weaker (Full syllabus 9B1).

A frequency counter has a timebase accuracy of 1 part in 10^6. If it is counting a 10MHz signal for a 1-second gate time, what is the maximum possible error in the reading?

  1. 1000 Hz
  2. 10 Hz
  3. 1 Hz
  4. 100 Hz

Answer: B, 10 Hz. An accuracy of 1 part in 10^6 on 10 MHz gives 10,000,000 × 10^-6 = 10 Hz maximum error. The gate time does not change this timebase error. See Full syllabus 9A6 (frequency counters and their limitations).

Which component is most susceptible to frequency drift due to temperature variations in an older receiver design?

  1. Crystal-referenced PLL synthesiser
  2. LC Tank Circuit
  3. Oven Controlled Crystal Oscillator
  4. Ceramic Resonator

Answer: B, LC Tank Circuit. An LC tank's inductance and capacitance both change with temperature, so the resonant frequency drifts. Full syllabus 9C1 covers temperature coefficients and their effect on tuned circuits, with remedial measures such as temperature compensation.