Question: The circuit is a

Options:

• A. 4:1 balun
• B. low-pass filter
• C. braid-breaker filter
• D. 1:1 balun

Correct Answer: D

Pool: 2025 Full - Feeder and Antenna Tag: AFA_1

Question: Which of the following is NOT a type of balun?

Options:

• A. Differential
• B. Transformer
• C. Sleeve
• D. Choke

Correct Answer: A

Pool: 2025 Full - Feeder and Antenna Tag: AFA_1

Question: What would the advantage be fitting a 1:1 balun to the centre of a dipole antenna of an amateur transceiver fed by coaxial cable?

Options:

• A. It would improve the reception
• B. It would minimise RF currents flowing on the outer braid of the coaxial cable
• C. It can boost the transmitter signal
• D. It would improve the impedance match between the antenna and the transmitter

Correct Answer: B

Pool: 2025 Full - Feeder and Antenna Tag: AFA_1

Question: A coaxial feeder cable is being used to feed a centre-fed half wave dipole. To reduce RF currents on the outer braid of the feeder; a length of braid from a larger cable is fitted over the outer insulation of the feeder. This braid should be

Options:

• A. as long as possible
• B. soldered to the feeder braid at the end closest to the antenna
• C. λ/4 long
• D. λ/2 long

Correct Answer: C

Pool: 2025 Full - Feeder and Antenna Tag: AFA_1

Question: The drawing shows a sleeve balun. How long should the sleeve be, and at which end should the sleeve be connected to the outer braid of the coaxial feeder?

Options:

• A. Connected at end 'A' and a quarter of a wavelength long.
• B. Connected at end 'A' and a half of a wavelength long.
• C. Connected at end 'B' and a quarter of a wavelength long.
• D. Connected at end 'B' and a half of a wavelength long

Correct Answer: A

Pool: 2025 Full - Feeder and Antenna Tag: AFA_1

Question: Due to the Velocity Factor, the physical length of antenna feeder is

Options:

• A. independent of its electrical length
• B. always less than its electrical length
• C. always the same as its electrical length
• D. always more than its electrical length

Correct Answer: B

Pool: 2025 Full - Feeder and Antenna Tag: AFA_1

Question: A length of coaxial cable with a polythene dielectric is cut to λ/4 at 10MHz. The physical length will be approximately

Options:

• A. 5m
• B. 7.5m
• C. 30m
• D. 15m

Correct Answer: A

Pool: 2025 Full - Feeder and Antenna Tag: AFA_1

Question: The ratio of the wavelength of a signal in a coaxial cable to the wavelength in free space is a measure of the

Options:

• A. velocity factor
• B. standing wave ratio
• C. frequency ratio
• D. transmitted frequency

Correct Answer: A

Pool: 2025 Full - Feeder and Antenna Tag: AFA_1

Question: A λ/4 length of solid polythene coaxial cable is required to match an antenna for the 2 metre band. Its length will be approximately

Options:

• A. 33cm
• B. 50cm
• C. 25cm
• D. 66cm

Correct Answer: A

Pool: 2025 Full - Feeder and Antenna Tag: AFA_1

Question: A λ/4 coaxial line transformer using air spaced coaxial cable is replaced with one using a solid polythene dielectric. The length of the replacement cable will be

Options:

• A. the same as the one it replaces
• B. about 2/3 of the one it replaces
• C. about half the length of the original
• D. 1.5 times the length of the one it replaces

Correct Answer: B

Pool: 2025 Full - Feeder and Antenna Tag: AFA_1

Question: A VHF FM broadcast programme on 100MHz is suffering interference from a 2m transmission nearby. A stub filter is proposed, a length of solid polythene dielectric coaxial cable to be connected in parallel with the existing feeder from the aerial in the roof. The coax stub should be about

Options:

• A. 52cm long and open circuit at the free end.
• B. 52cm long and short circuit at the free end.
• C. 34cm long and open circuit at the free end.
• D. 34cm long and short circuit at the free end.

Correct Answer: C

Pool: 2025 Full - Feeder and Antenna Tag: AFA_1

Question: The power output of a piece of equipment is specified in Peak Envelope Power. What type of output is this?

Options:

• A. The DC input power stage of an SSB transmitter
• B. The AF power output of an SSB receiver
• C. The RF power output of an SSB transmitter
• D. The AF power to the transmitter modulator

Correct Answer: C

Pool: 2025 Full - Measurements and construction Tag: AMC_2

Question: Peak envelope power (PEP) is the power

Options:

• A. averaged over one audio cycle of maximum modulation
• B. in the unmodulated carrier
• C. over one RF cycle at the crest of the modulation
• D. obtained by doubling the carrier power on SSB

Correct Answer: C

Pool: 2025 Full - Measurements and construction Tag: AMC_2

Question: An amateur band extends from 28.000MHz to 29.700MHz. To mark the edges of the band, a crystal calibrator needs to have a fundamental frequency of

Options:

• A. 200kHz
• B. 1MHz
• C. 100kHz
• D. 10MHz

Correct Answer: C

Pool: 2025 Full - Measurements and construction Tag: AMC_3

Question: For a home-built transmitter that covers the 3.5MHz to 3.8MHz band, which of the following devices is the most appropriate to accurately measure the frequency of the transmitter?

Options:

• A. An absorption frequency meter
• B. An SWR meter
• C. A dip oscillator
• D. A digital frequency meter

Correct Answer: D

Pool: 2025 Full - Measurements and construction Tag: AMC_3

Question: Which ONE of the following would be used to check for the second and third harmonics, when using a transmitter which is set to a frequency of 14.150MHz?

Options:

• A. An RF power meter
• B. An SWR meter
• C. An HF/VHF receiver
• D. A digital frequency meter

Correct Answer: C

Pool: 2025 Full - Measurements and construction Tag: AMC_3

Question: The accuracy of a digital frequency counter is determined by the

Options:

• A. number of digits on the display
• B. the internal crystal oscillator
• C. strength of the signal being measured
• D. depth of modulation of the signal

Correct Answer: B

Pool: 2025 Full - Measurements and construction Tag: AMC_3

Question: To check the frequency of a transmitter in the 40m and 10m bands a crystal calibrator with a 1MHz crystal and switchable divide by 10 integrated circuit is better than one with just a 100kHz crystal because

Options:

• A. the percentage frequency drift of the 1MHz crystal will be reduced by a factor of 10
• B. it is more difficult to find the correct harmonic of a 100kHz
• C. 1MHz crystals are more readily available if a replacement is required
• D. lower frequency crystals have a higher temperature coefficient

Correct Answer: B

Pool: 2025 Full - Measurements and construction Tag: AMC_3

Question: A meter connected between point A and earth will indicate

Options:

• A. Return Loss
• B. Reverse Power
• C. Standing Wave Ratio
• D. Forward Power

Correct Answer: D

Pool: 2025 Full - Measurements and construction Tag: AMC_3

Question: The oscilloscope displaying the waveform shown is set to a sensitivity of 5mV per division and timebase 1ms per division. What is the peak amplitude of the waveform?

Options:

• A. 20mV
• B. 25mV
• C. 40mV
• D. 5mV

Correct Answer: A

Pool: 2025 Full - Measurements and construction Tag: AMC_3

Question: What device is shown in the circuit diagram?

Options:

• A. Deviation monitor
• B. Heterodyne wave-meter
• C. Absorption wave-meter
• D. SWR meter

Correct Answer: D

Pool: 2025 Full - Measurements and construction Tag: AMC_3

Question: In the device shown the switch would be labelled

Options:

• A. On/Off
• B. Forward/Reverse
• C. VHF/UHF
• D. High Power/Low Power

Correct Answer: B

Pool: 2025 Full - Measurements and construction Tag: AMC_3

Question: In the diagram below, the two meters are used to indicate

Options:

• A. Whether the feeder is balanced
• B. Forward and Reflected Power
• C. Resistance and Current
• D. The velocity factor of the feeder

Correct Answer: B

Pool: 2025 Full - Measurements and construction Tag: AMC_3

Question: In the diagram below, what are the two meters are used to measure?

Options:

• A. Resistance and Current
• B. The velocity factor of the feeder
• C. Forward and Reflected Power
• D. Whether the feeder is balanced

Correct Answer: C

Pool: 2025 Full - Measurements and construction Tag: AMC_3

Question: The circuit below shows

Options:

• A. a standing wave ratio meter
• B. a low power balun
• C. a feeder velocity factor meter
• D. an antenna matching unit (AMU)

Correct Answer: A

Pool: 2025 Full - Measurements and construction Tag: AMC_3

Question: The diagram shows an oscilloscope trace of a sine wave with significant second harmonic distortion. The oscilloscope settings are; time base 500ns/division, y-axis 20mV/division. What is the frequency of the fundamental signal and its peak amplitude?

Options:

• A. Frequency 250kHz Amplitude 70mV
• B. Frequency 2.5MHz Amplitude 35mV
• C. Frequency 250kHz Amplitude 35mV
• D. Frequency 2.5MHz Amplitude 70mV

Correct Answer: A

Pool: 2025 Full - Measurements and construction Tag: AMC_3

Question: The trace on an oscilloscope occupies most of the height of the screen and about two cycles are shown across the screen but is drifting to the left. To stabilise the drift which control should be adjusted?

Options:

• A. the trigger control until the trace stabilises
• B. the time base to less time per division
• C. the time base to more time per division
• D. the amplitude control until the trace stabilises

Correct Answer: A

Pool: 2025 Full - Measurements and construction Tag: AMC_3

Question: An oscilloscope is displaying 10 cycles of RF from a transmitter on the 20m band. The transmitter is changed to the 40m band. Which adjustment should be made to display 10 cycles on the new band?

Options:

• A. Set the X gain control to twice its current V/cm setting
• B. Set the timebase to twice the previous µs/cm value
• C. Set the Y gain control to twice its current V/cm setting
• D. Set the timebase to half the previous ¬µs/cm value

Correct Answer: B

Pool: 2025 Full - Measurements and construction Tag: AMC_3

Question: An oscilloscope is displaying an AC signal showing 6 cycles across 6 divisions on the x-axis of the screen. The time base is set to 10ms per division. What is the frequency of the AC signal?

Options:

• A. 60Hz
• B. 1kHz
• C. 100Hz
• D. 600Hz

Correct Answer: C

Pool: 2025 Full - Measurements and construction Tag: AMC_3

Question: An oscilloscope is displaying an AC signal showing 5 cycles across 5 divisions on the x-axis of the screen. The time base is set to 5µs per division. What is the frequency of the AC signal?

Options:

• A. 5MHz
• B. 25kHz
• C. 5kHz
• D. 200kHz

Correct Answer: D

Pool: 2025 Full - Measurements and construction Tag: AMC_3

Question: A transmitter being used on 432.2MHz SSB is known to have a very small frequency error but a high temperature dependent drift of approximately 2ppm per degree C. A temperature rise of 10 degrees C is not unusual. The most significant effect of this is likely to be

Options:

• A. a modest distortion of the audio in the distant receiver
• B. unintentional radiation outside the amateur 70cm band
• C. a need to constantly adjust the RIT at the distant receiver
• D. interference to other amateurs on adjacent frequencies

Correct Answer: D

Pool: 2025 Full - Transmitters and Receivers Tag: ATR_2

Question: Which situation is likely to result in drift in the first 5 to 10 minutes after starting operation?

Options:

• A. Running the oscillator on a separate lower voltage power supply
• B. Inadequate biasing of the frequency multiplier stages
• C. Winding the oscillator coils on a ceramic former
• D. Placing the master oscillator close to the power amplifier stage

Correct Answer: D

Pool: 2025 Full - Transmitters and Receivers Tag: ATR_2

Question: What is the most likely effect of a transmitter on 145.000MHz suffering from severe drift of the order of 200ppm?

Options:

• A. Transmitting outside the amateur band.
• B. Some audible distortion in the intended receiver.
• C. Interfering with frequencies used by other contacts.
• D. Increased noise level over most of the amateur band.

Correct Answer: C

Pool: 2025 Full - Transmitters and Receivers Tag: ATR_2

Question: Question Text

Options:

• A. Option A
• B. Option B
• C. Option C
• D. Option D

Correct Answer: Correct Response

Pool: Question Pool Tag: Tag

Question: Question Text

Options:

• A. Option A
• B. Option B
• C. Option C
• D. Option D

Correct Answer: Correct Response

Pool: Question Pool Tag: Tag

Question: A transmitter performs all the modulation functions at a fixed frequency of 8.0MHz and then mixes the modulated signal up to 145MHz. What frequency should the filter following the balanced mixer take particular care to REJECT.

Options:

• A. 137MHz
• B. 153MHz
• C. 145MHz
• D. 129MHz

Correct Answer: D

Pool: 2025 Full - Transmitters and Receivers Tag: ATR_1

Question: The box marked 'X' in the SSB transmitter shown is the

Options:

• A. carrier oscillator.
• B. sideband filter.
• C. final frequency mixer.
• D. variable frequency oscillator.

Correct Answer: A

Pool: 2025 Full - Transmitters and Receivers Tag: ATR_1

Question: The box marked X in the FM transmitter shown is the

Options:

• A. frequency synthesiser
• B. frequency multiplier
• C. final frequency mixer
• D. balanced modulator

Correct Answer: B

Pool: 2025 Full - Transmitters and Receivers Tag: ATR_1

Question: The box marked 'X' in the SSB transmitter block diagram is the

Options:

• A. sideband filter
• B. frequency synthesiser
• C. beat frequency oscillator
• D. mixer

Correct Answer: B

Pool: 2025 Full - Transmitters and Receivers Tag: ATR_1

Question: The diagram shows part of a transmitter for the 21MHz band. The modulator is operating at 8MHz. A good choice of frequency for the VFO is

Options:

• A. 29MHz
• B. 21MHz
• C. 13MHz
• D. 5MHz

Correct Answer: A

Pool: 2025 Full - Transmitters and Receivers Tag: ATR_1

Question: The purpose of a buffer amplifier stage is often to

Options:

• A. provide ample PD to drive the power amplifier stage
• B. isolate the oscillator stage from subsequent stages
• C. supply the major part of amplification of the modulated signal
• D. protect the driver stage from over modulation

Correct Answer: B

Pool: 2025 Full - Transmitters and Receivers Tag: ATR_1

Question: In frequency modulation if the audio input is increased in amplitude then the

Options:

• A. modulation index increases and number of significant sidebands is unchanged.
• B. modulation index and number of significant sidebands increase.
• C. modulation index is unchanged but the number of significant sidebands increases.
• D. modulation index reduces but the number of significant sidebands increases.

Correct Answer: B

Pool: 2025 Full - Transmitters and Receivers Tag: ATR_1

Question: The number of relevant FM sidebands is directly related to the

Options:

• A. Deviation Ratio.
• B. Modulation Index.
• C. peak system deviation.
• D. amplitude of the audio signal.

Correct Answer: B

Pool: 2025 Full - Transmitters and Receivers Tag: ATR_1

Question: An FM transmission has only two sidebands, one above and one below the carrier. That must mean that the

Options:

• A. modulation index is low.
• B. bandwidth is low.
• C. audio frequency is low.
• D. deviation is low.

Correct Answer: A

Pool: 2025 Full - Transmitters and Receivers Tag: ATR_1

Question: The Modulation Index of a frequency modulated transmission is given by

Options:

• A. Actual deviation/Peak deviation
• B. Peak deviation/Max audio frequency
• C. Max audio frequency/Actual deviation
• D. Actual deviation/Bandwidth

Correct Answer: A

Pool: 2025 Full - Transmitters and Receivers Tag: ATR_1

Question: As the Modulation Index of an FM transmission increases it is ALWAYS the case that the

Options:

• A. volume of the received audio signal increases.
• B. frequency of the received audio signal increases.
• C. number of sidebands required increases.
• D. bandwidth of the transmission increases.

Correct Answer: C

Pool: 2025 Full - Transmitters and Receivers Tag: ATR_1

Question: The spectrum of an FM signal is being displayed on a spectrum analyser which is showing the individual sidebands generated by a single audio tone of variable frequency and amplitude. An increasing number of sidebands must mean that the

Options:

• A. deviation ratio is increasing.
• B. audio volume is increasing.
• C. audio frequency is increasing.
• D. modulation index is increasing.

Correct Answer: D

Pool: 2025 Full - Transmitters and Receivers Tag: ATR_1

Question: Because of the end factor correction, the actual length of a λ/2 dipole antenna is approximately

Options:

• A. 5% less than the electrical length
• B. 5% greater than the electrical length
• C. 10% greater than the electrical length
• D. 10% less than the electrical length

Correct Answer: A

Pool: 2025 Full - Feeder and Antenna Tag: AFA_2

Question: For a 30MHz half-wave dipole antenna, the length of wire on each side of the central insulator is approximately

Options:

• A. 10m
• B. 4.75m
• C. 5.0m
• D. 2.4m

Correct Answer: D

Pool: 2025 Full - Feeder and Antenna Tag: AFA_2

Question: How long is a typical half wave dipole tuned for the centre of the 1.8MHz band?

Options:

• A. 52.75m
• B. 75.00m
• C. 78.74m
• D. 157.48m

Correct Answer: B

Pool: 2025 Full - Feeder and Antenna Tag: AFA_2

Question: How long is the optimum length of a half-wave dipole for the centre of the 3.5MHz - 3.8MHz band?

Options:

• A. 39m
• B. 40.7m
• C. 41.1m
• D. 82.2m

Correct Answer: A

Pool: 2025 Full - Feeder and Antenna Tag: AFA_2

Total questions: 51

Categories: 8

Questions by Pool:

• 2025 Full - Feeder and Antenna: 15 questions
• 2025 Full - Measurements and construction: 19 questions
• 2025 Full - Transmitters and Receivers: 15 questions
• Question Pool: 2 questions