📻 CQ PE1NAO (Netherlands · JO32) on 7.075 MHz FT8 at 12:51 UTC
Full Question Bank (All Categories)
Full Question Bank (All Categories)
The complete RSGB Full Level question bank, all sections combined for mixed practice.
571 multiple-choice questions across all 9 syllabus sections
Prefer to focus on one topic at a time? Each section also has its own dedicated deck — see the flashcards index.
Some questions include a reference diagram or circuit image
Turn on shuffle below, since this is a large pool
Full Level - Syllabus V1.6b
Before you start, you may want to open the official RSGB reference data sheet
(band plans, frequency tables, conversions) — it's allowed for use during the real exam too.
🔀 Practice Mode — random question, not scored. Click an option to reveal the answer.
2025-Full439
The licensee may, in any operations conducted under the licence
2025-Full6007
You are helping at a field first aid post tent run by St John Ambulance when a paramedic asks you to send a message relating to a particular patient. It is clear that some details are deliberately obscured. You should
2025-Full6008
Under what circumstances, if any, is it permissible to send a message the meaning of which has been obscured?
2025-Full6009
Which one of the following messages is subject to licence restrictions?
2025-Full7651
Which one of the circumstances listed would allow you to pass an encrypted message on behalf of another person?
2025-Full8111
What is the difference between using codes and encrypting a message?
2025-Full8112
What are the occasions where use of encryption is in accordance with the licence terms?
2025-Full8109
A point to bear in mind, when contacting overseas amateurs, is that
2025-Full8110
How should you behave on-air considering that amateurs will have diverse cultural norms and sensitivities?
2025-Full8126
You are on 2m having a conversation with a friend when another radio amateur comes in on the conversation and indicates he finds the subject of your conversation offensive. Do you:-
2025-Full6010
Testing a home-made VFO shows it is stable to about 1%. What is the most serious problem you are likely to encounter on-air when using it for transmitting on 14.346 MHz upper sideband?
2025-Full75
Your Licence requires that your amateur station MUST NOT cause
2025-Full8081
What is the best reason for avoiding causing Undue Interference to other radio users?
2025-Full8082
Some amateur facilities will receive transmissions in one band and re-transmit them in a different band: so why is it desirable to have the ability to receive on both bands?
2025-Full8001
An amateur must ensure that possible exposure to electro-magnetic fields from their station is within the ICNIRP guidelines in
2025-Full8003
The determination of the safe levels for human exposure to electromagnetic fields were performed on behalf of the
2025-Full8006
What is the area over which the general public need to be protected from electromagnetic fields exceeding the specified limits?
2025-Full8008
What is the purpose of considering the transmission mode when assessing electromagnetic field compliance?
2025-Full8009
When conducting an EMF assessment, what is the purpose of considering the proportion of the time spent transmitting over any 6-minute time period?
2025-Full8017
Why does the mode of transmission matter when assessing compliance with the licence requirement for electromagnetic fields?
2025-Full4060
When operating on 5.300MHz the maximum radiated power must not exceed
2025-Full4092
You are operating on the 60m band and form a net with a group of radio amateurs. In order to comply with your licence conditions you must give your callsign
2025-Full76
Which one of the following bands is NOT authorised under the terms of the Amateur Radio Licence?
2025-Full7657
When operating within the 5MHz band while at a temporary location you must give the location of your station to an accuracy of at least
2025-Full7658
When operating within the 5MHz band while at a temporary location you must
2025-Full3972
It is proposed to set up a data repeater and tests on the filtering show that for adequate suppression the transmit and receive signals need to be 12MHz apart. The lowest frequency amateur band that might be suitable is the
2025-Full8113
Operation on part of the UHF frequency band is restricted close to London. What distance is given in the licence.?
2025-Full8114
Which frequency band required written consent from Ofcom?
2025-Full8115
Which amateur band is partly limited to a Peak Envelope Power Limit of 40W ERP?
2025-Full8116
On which amateur band are you limited to at transmit power of 100W?
2025-Full8117
On which of the following frequencies may a satellite transmit to Earth but on which you must not reply?
2025-Full7660
Unattended beacons operating at 1298.5MHz cannot be set up in
2025-Full8118
On which amateur band does a proposal to deploy a repeater, beacon, gateway or data station require Ofcom to co-ordinate with the CAA?
2025-Full8119
What is the power limit in the 70cm band above which a beacon requires co-ordination with the MOD?
2025-Full8120
What is the restriction in the 2m band applying to a Beacon within 50km of NGR TA 012869?
2025-Full8121
Before submitting a request for clearance to Ofcom in the 1240 to 1325MHz bands it is first necessary to
2025-Full3361
The circuit diagram shows an NPN transistor being used as an amplifier. The potential difference across the Base-Emitter junction is 0.6Volt and there is 1V across Re. Which resistor may be used for R1 in order to create the correct transistor bias. You may assume the base current is insignificant.
2025-Full459
A 50Ω dummy load is connected to a transceiver and 100V of RF is noted on transmit. What is the transceiver's output power?
2025-Full7664
What current will be drawn from the battery?
2025-Full7666
There is 6V across the 1kΩ resistor. What is the battery voltage?
2025-Full7667
The 1kΩ resistor is dissipating 2W of heat. What is the dissipation in the 4kΩ resistor?
2025-Full3555
The diagram shows an air spaced capacitor. Sheets of glass are inserted to fill the spaces between the plates. What effect will this have?
2025-Full460
A capacitor can have its capacitance reduced by
2025-Full8026
As the frequency increases from LF to UHF it is likely that for plastic film capacitors
2025-Full4063
You notice the polythene capacitors in the output filter of your HF transmitter get warm when operating on 29MHz but not so on 1.8MHz even though you are running at a higher power since your antenna is less efficient on the lower frequency. This is probably because
2025-Full98
As a general rule, the losses associated with the dielectric of a capacitor
2025-Full7886
A capacitor is marked as 0.1µF 250V. What does the 250V parameter indicate?
2025-Full95
Which of the following factors would be most important in selecting a suitable reservoir capacitor for use in a mains power supply unit?
2025-Full96
Using a capacitor above its breakdown voltage is likely to
2025-Full104
As the current through a coil increases the resultant magnetic field causes an effect that opposes the increase. This is known as the
2025-Full105
The back EMF created when a current changes, is due to the
2025-Full106
Self Inductance is the inductance
2025-Full3689
The switch in the diagram is initially closed and the current is steady. The switch is then opened and a spark is seen to pass between the switch contacts. The reason for this is that the
2025-Full7674
The drawing shows the circuit of a switching transistor controlling the current in the coil of a relay. The base is fed with regular pulses to cause the relay contacts to close. Which circuit will minimise the voltage spikes caused by the the switching?
2025-Full7706
In the case of self-inductance, the magnetic field created by a changing
2025-Full110
An inductor of negligible resistance is inserted in a series circuit comprising a battery and a resistor. Its effect will be to
2025-Full3556
The neon bulb in the figure needs about 65V to cause it to 'strike'. Approximately how long after switch on will it light?
2025-Full3690
A series circuit is made from an inductor, resistor and switch connected to a battery. At the instant the switch is closed there is zero current in the circuit. The reason for this is that the
2025-Full462
A high voltage power supply for a valve transmitter produces about 1500V. The smoothing capacitor is 100µF and the bleeder resistor is 600kΩ. 1 minute after switch-off the PD across the capacitor will be approximately
2025-Full7676
The switch S in the diagram is closed at time t=0. Which graph correctly shows the voltage across the resistor after the switch is closed?
2025-Full7889
The drawing shows part of the circuit of a Morse key. The voltage source and 1kΩ resistor are inside the transmitter and the coil is added externally to slow the rise and fall of the keying waveform. What is the time constant of the keying circuit?
2025-Full118
In constructing an antenna matching circuit, a capacitor with a reactance of about 190Ω at 7MHz is required. The most suitable value of capacitor would be
2025-Full120
The reactance of a 1µH inductor at 16MHz is approximately
2025-Full124
The graph shows the potential differences (PD) in a circuit comprising a resistor and a capacitor connected in series and fed from an AC source.
2025-Full671
The reactance of the inductor in a 14MHz antenna trap is known to be 200Ω. The capacitor required to complete the tuned circuit would need to have a value of approximately
2025-Full127
In the circuit shown, C1 is used as
2025-Full3322
The circuit diagram shows an oscillator. The function of capacitor C relies upon the ability of a capacitor to
2025-Full7679
A 0.1mH ferrite cored coil is fitted on the back of the microphone socket of a transceiver so it is in series with the connection to the circuit board and microphone amplifier. What is its likely purpose?
2025-Full3569
In the circuit shown the RMS voltage between points A and B will be approximately
2025-Full4076
A resistor of 4000Ω and a capacitor of 27pF are connected in series. What is the impedance of the combination at 1.965MHz?
2025-Full758
A 1000Ω resistor is in series with a pure reactance of 1000Ω. What is the approximate impedance of this series circuit?
2025-Full771
A 300Ω resistor and an 8µF capacitor are connected in series to the secondary of a 50 to 1 (50:1) ratio step-down transformer the primary of which is connected to a 250V 50Hz mains supply. What current will flow through the resistor?
2025-Full6015
To digitize an analogue signal within the range 20Hz to 14kHz, which is the lowest sample rate that will capture the signals?
2025-Full6019
An anti-alias filter should be positioned
2025-Full7395
A phenomenon known as aliasing is caused by
2025-Full7645
A software defined receiver is sampling the output of the RF front end amplifier at 80M samples/s. Which filter response should be incorporated in the RF amplifier to avoid aliasing?
2025-Full7401
The process termed a Fast Fourier Transform
2025-Full7686
The top graph is a spectrum analyser plot of a sinewave and a harmonic. Which TWO plots of the same signal in the time domain does the spectrum plot refer to?
2025-Full7864
The Fourier Transform converts
2025-Full7890
The drawing shows the block diagram of a radio receiver and the signals at points between some of the blocks. Which option best describes the function of block 2?
2025-Full159
The mutual inductance of a transformer is
2025-Full166
A transformer has a potential difference of 100V AC applied to its primary, which results in a primary current of 1A. The potential difference measured at the secondary is 20V AC. The secondary current is
2025-Full170
A transformer with 25 turns on the primary and 5 turns on the secondary, has a 1kΩ resistor connected to the secondary. The impedance measured at the primary will be
2025-Full673
The circuit of a transformer balun is shown in the diagram. The primary is connected to 50Ω coaxial cable and the secondary to open wire feeder. An appropriate impedance for the feeder would be
2025-Full774
A half-wave folded dipole antenna is fed by 300Ω impedance twin feeder. It is connected to the transmitter by a transformer balun as shown in the diagram. What impedance does the primary of this present to the transmitter?
2025-Full7761
Filter circuits using inductors normally specify the 'mix' of the ferrite. Why?
2025-Full129
The inductor in a 14MHz antenna trap is 2µH. The capacitor required to complete the tuned circuit would need to have a value of approximately
2025-Full130
You construct a variable frequency oscillator with a 5µH inductor and a capacitor with a range of 5 to 50pF as the tuned circuit. The lowest frequency it will oscillate at is
2025-Full132
A capacitor and inductor in a parallel tuned circuit resonate at 70.3MHz. The resonant frequency will be reduced if
2025-Full144
A quartz crystal
2025-Full147
Which single component exhibits both series and parallel resonance?
2025-Full3573
The circuit shown
2025-Full134
The drawing shows the response curve of a tuned circuit , its Q-factor is
2025-Full150
Components in a tuned circuit may need high voltage and current ratings because
2025-Full691
A parallel tuned circuit has a Q-factor of 80 and is resonant at 10MHz and it is noted that the current in to the circuit is 100µA. An approximate value for the circulating current would be
2025-Full138
The dynamic resistance of an LCR circuit
2025-Full139
Dynamic resistance is an effect associated with
2025-Full300
A zener diode is intended to conduct when the
2025-Full3418
Which of the graphs shown shows the characteristics of a Zener diode? Forward bias is shown to the right.
2025-Full3577
The graph shows the characteristic curve of
2025-Full3983
What current is flowing through the diode shown in the diagram?
2025-Full319
In the field-effect transistor, the 'pinch-off' voltage is the bias required on the
2025-Full3582
In the diagram the potential at point A is reduced. The effect of this will be
2025-Full3585
The circuit shows an n-channel depletion mode FET amplifier. The potential at the gate should be approximately
2025-Full679
The transistor amplifier shown is correctly biased. R2 is 22kΩ. A suitable value for R1 would be about
2025-Full321
The circuit shown has a voltage gain of
2025-Full322
The circuit shown has a voltage gain of
2025-Full323
The circuit shown has a CURRENT gain of
2025-Full324
Which class of amplifier has the lowest distortion?
2025-Full325
Biasing an NPN transistor so that only the positive parts of the signal are amplified is a description of
2025-Full3404
One feature of a transistor amplifier biased in class C is that
2025-Full7635
In order that an oscillator circuit will oscillate, the gain in the transistor amplifier must
2025-Full7738
The voltage gain in a transistor oscillator circuit must be
2025-Full7739
In an oscillator the gain in the transistor amplifier must be
2025-Full7764
In order to maintain oscillations in a transistor oscillator circuit the
2025-Full7765
If the attenuation in the tuned circuit feedback of an oscillator is greater than the gain of the transistor amplifier then
2025-Full7766
An oscillator is utilising its transistor in emitter follower mode. The phase change of the signal in the feedback circuit must be
2025-Full3427
In the regulated power supply circuit shown the output voltage is 24V. The zener diode should have a voltage of
2025-Full350
The reference voltage in a stabilised mains operated power supply is provided by the
2025-Full352
The output voltage of a stabilised mains operated power supply is often controlled by a
2025-Full3595
It is likely that the device marked 'X' in the drawing is
2025-Full3794
The circuit shows a stabilised power supply. The desired output is 13.4V and the resistors R1 and R2 are both 10kΩ. The zener diode should have a voltage of about
2025-Full7767
Which statement is true in respect of a linear power supply?
2025-Full3428
The diode shown in the power supply for a transmitting valve should have a reverse voltage (PIV) of at least
2025-Full344
The rectifier diodes in a mains operated 12V stabilised power supply have failed and must be replaced. Which of the following diodes would be chosen to replace them?
2025-Full347
A simple power supply consists of a transformer feeding a single diode and capacitor in a half wave circuit. The transformer secondary voltage is 20Vrms. The peak inverse voltage across the diode will be about
2025-Full348
A mains power supply consists of a transformer with a single diode and smoothing capacitor on the transformer secondary. The peak inverse voltage (PIV) across the diode will be approximately equal to
2025-Full3593
If the secondary voltage from the transformer is 10V rms the peak inverse voltage rating (PIV) of the diode should be at least
2025-Full4077
A small power supply is shown in the diagram. The diode should be chosen so its reverse voltage rating is at least
2025-Full7002
What type of component is in the box marked X?
2025-Full7682
The control mechanism monitoring the output voltage of a switch mode power supply is typically fed back to the switching circuits via an optical coupler or other non-conducting means. Why?
2025-Full7741
The size of a smoothing capacitor on the output of a switched mode power supply can be much smaller than the equivalent capacitor on a conventional linear supply. Why?
2025-Full7770
A switched mode power supply is more efficient than a linear one because
2025-Full7771
A concern with the use of switched mode power supplies is that
2025-Full7808
A key difference between a switched mode power supply and a linear one is that
2025-Full7759
A LC oscillator has been designed to oscillate at 8 MHz. You are confident of the accuracy of the capacitor but the inductor is 2% low in value. What will be the frequency of oscillation?
2025-Full7884
The drawing shows an FET circuit biased by R1 and R2. R1 is 80kΩ and R2 is 20kΩ. Both resistors are 10% tolerance. The bias voltage might be lower than its design value by a maximum of
2025-Full7966
Identify all the capacitors (if any) where the tolerance on their actual value will have an effect on the lowest frequency which the amplifier shown will handle.
2025-Full7967
Identify all the capacitors (if any) where the tolerance on their actual value will have an effect on the highest frequency which the amplifier shown will handle.
2025-Full8066
The drawing shows a potential divider where R1 is 80kΩ and R2 is 20kΩ. Both resistors are 5% tolerance. What is the maximum deviation of the output voltage from its design value?
2025-Full381
A wideband FM transmission is one where the
2025-Full7637
In frequency modulation if the audio input is increased in amplitude then the
2025-Full7742
An FM transmission has only two sidebands, one above and one below the carrier. That must mean that the
2025-Full7772
The Modulation Index of a frequency modulated transmission is given by
2025-Full7773
As the Modulation Index of an FM transmission increases it is <strong>ALWAYS</strong> the case that the
2025-Full7774
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
2025-Full3408
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.
2025-Full3598
The box marked 'X' in the SSB transmitter shown is the
2025-Full3600
The box marked X in the FM transmitter shown is the
2025-Full3602
The box marked 'X' in the SSB transmitter block diagram is the
2025-Full4078
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
2025-Full682
The purpose of a buffer amplifier stage is often to
2025-Full8029
The oscillator in an HF transmitter is based on an LC tuned circuit and is specified as having a maximum drift of 0.1%. An important effect of this is that a CW signal in the 10MHz amateur band
2025-Full3410
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
2025-Full3987
Which situation is likely to result in drift in the first 5 to 10 minutes after starting operation?
2025-Full7897
What is the most likely effect of a transmitter on 145.000MHz suffering from severe drift of the order of 200ppm?
2025-Full3606
In the block diagram of a frequency synthesiser the arrowed box contains
2025-Full7743
What function is performed in the box marked X?
2025-Full3349
When a sinusoidal output is produced from a direct digital synthesiser (DDS), the number of bits the synthesiser can generate will affect the
2025-Full3406
The size of the frequency steps in a phase locked loop frequency synthesiser is set by the
2025-Full354
If a sine wave is produced by direct digital synthesis, the purity of the output is determined mainly by the
2025-Full3791
When a sine wave is produced from a direct digital synthesiser, the number of bits the synthesiser can generate will affect the
2025-Full365
Why do frequency multiplier stages usually operate in Class C?
2025-Full368
A single-channel transmitter intended for operation on 70.26MHz uses a crystal oscillator on 5855kHz. The final frequency is most likely to be produced by
2025-Full374
The function of the multiplier stage in a transmitter is to
2025-Full688
It is proposed to generate a microwave signal by feeding the output of a UHF transmitter to a frequency multiplier circuit. This arrangement is suitable for use with
2025-Full738
A modulated UHF signal is available to feed a 10GHz microwave transmitter. The transmitted frequency is 10.38GHz. A suitable multiplier frequency for the UHF source is
2025-Full384
Which of the following modulation types is often generated by varying the voltage applied to a varicap in an RF oscillator?
2025-Full391
Increasing the deviation level of a frequency modulated transmitter
2025-Full393
A single sideband transmitter is operating on lower sideband on 1.960MHz and is modulated with a pure 3000Hz tone. The RF output frequency will be
2025-Full683
In an amateur radio transceiver, the depth of modulation for radio telephone transmissions can be varied by use of the
2025-Full686
A 1MHz carrier is frequency modulated by a 1kHz audio signal amplitude 100mV and causing a peak deviation of 2.5kHz. The occupied bandwidth of the transmission is approximately
2025-Full716
An FM broadcast transmitter uses a peak deviation of 75kHz and a maximum audio frequency of 15kHz. The bandwidth of the transmission is approximately
2025-Full7745
The circuit shown is likely to be found
2025-Full7746
A transmitter is set to 7.150MHz LSB. The balanced modulator has a 6.000MHz carrier and its output will subsequently be mixed up to the transmit frequency by a synthesiser on 13.150MHz. The sideband filter should be set to pass
2025-Full7775
A superhet receiver is tuned to an upper sideband signal on 144.500MHz. The local oscillator is running at 140.500MHz. The sideband filter to admit the signal should be set to
2025-Full7778
A superhet receiver is tuned to a lower sideband signal on 144.500 MHz. The local oscillator is running at 148.500 MHz. The sideband filter to admit the signal should be set to
2025-Full7779
In the circuit shown the crystals are set to 9.0 MHz, the capacitors to 39pF and the overall Q factor is 3330. What is the most likely function of the circuit?
2025-Full7780
A crystal filter 2.7kHz wide is used to select the wanted sideband in the IF of a superhet receiver. Rather than set up another filter for the other sideband an alternative option is to offset the local oscillator by
2025-Full398
You are intending to add an SSB transmit amplifier to your Station. The amplifier should be
2025-Full399
An RF power amplifier operates class C. It is suitable for
2025-Full717
A good SSB transmitter is feeding a power amplifier that is rather non-linear but does have a good low pass filter on its output. The most significant effect of the non-linearity will be
2025-Full7785
A non-linear amplifier fed with two sinusoidal input signals will produce
2025-Full7787
An SSB RF amplifier is being driven by two RF signals at 14.101 MHz and 14.102 MHz when it is noticed that there is also an output on 14.103 MHz. What action is most likely to clean up the signal?
2025-Full7788
The drawing shows the spectrum of the input and output of an external RF power amplifier being fed from an SSB transmitter. The most likely explanation for the change in the spectrum is that
2025-Full402
A pi-network in the output stage of a transceiver
2025-Full403
In a transmitter PA stage a pi-network is used for impedance matching. It also can act as a
2025-Full405
The output circuits of an RF power amplifier normally fulfil two functions, filtering and
2025-Full408
Which mode of transmission will result in the greatest average power requirement from the final amplifier? Assume the PEP is the same in all cases.
2025-Full409
The effect on the RF power amplifier of switching on speech processing in an SSB transmitter will be
2025-Full410
A transmitter is normally used on SSB and runs comfortably warm even when peaking at 100W output. It is decided to use the same transmitter on RTTY (radio teletype) and the input level is set so the RF output peaks at the same level as previously used on voice. It is likely that the transmitter will run
2025-Full411
A class AB transmitter has been in use for some time and the speech processor is then switched on and set to maximum compression. The peak transmit power is seen to be unaffected. It is LIKELY that the transmitter will run
2025-Full412
Using a speech processor in an SSB transmitter will
2025-Full3280
A transceiver is fitted with an automatic level control (ALC). This will
2025-Full413
The purpose of Automatic Level Control (ALC) in a transmitter is to
2025-Full415
An external RF power amplifier (PA) has 3 leads marked '240V AC', 'RF in' and 'ALC'. The ALC lead
2025-Full697
A transceiver is fitted with an automatic level control (ALC). This will
2025-Full3411
Over modulation of an RF carrier is likely to result in
2025-Full4081
When the spectrum of an HF AM transmitter is observed over a narrow range, it is noticed that as the modulation depth is changed there is a point beyond which several harmonics of the audio signal appear. At that point the depth of modulation will be
2025-Full474
Over modulation of an SSB transmitter results in excessive RF bandwidth because the greater amplitude of the AF signal causes
2025-Full475
Even though your microphone amplifier has good audio frequency bandwidth filtering you find that your transmissions occupy excessive RF bandwidth. A likely cause is
2025-Full476
Over modulation may be caused by excessive
2025-Full3990
A cause of intermodulation products in a separate RF power amplifier (PA) is
2025-Full485
Overdriving an external power amplifier with a transmitter is likely to
2025-Full486
An operator should not overdrive an external power amplifier with a transmitter in order to avoid
2025-Full489
You should not overdrive an external power amplifier so as to avoid
2025-Full7789
The drawing shows the spectrum of the input and output of an external RF power amplifier. It is most likely that the
2025-Full7790
An amateur is receiving complaints that his transmissions are causing interference to other stations immediately above and below his transmitted frequency. The amateur should check that
2025-Full430
Harmonics in a transmitter would NOT be reduced by using
2025-Full432
Which of the following is most likely to cause harmonics?
2025-Full465
The response of a transmitter's low pass filter should fall sharply above the cut off frequency to attenuate the transmission of
2025-Full466
A low-pass filter fitted at the output of a transmitter will
2025-Full467
A transmitter for the 160 metre band is found to radiate on other amateur bands. What action could be taken to prevent this?
2025-Full4080
An FET HF RF power amplifier occasionally suffers from parasitic oscillation at a frequency much higher than the designed operating frequency. Which of the four options is most likely to be successful?
2025-Full469
Stray coupling in a Power Amplifier may be the cause of
2025-Full470
Unwanted parasitic oscillations may occur as a result of
2025-Full472
The lead to the base of the power amplifier transistor in an RF PA is connected via a low value resistor with a few turns of wire, wound round the resistor and in parallel with it. The purpose of this circuit is to
2025-Full473
Parasitic oscillations in a transistor amplifier may often be cured by
2025-Full3412
A phase locked loop synthesiser in a transmitter has an output to indicate that the control loop is phase locked. If this indication is absent it is necessary to
2025-Full3617
If a phase lock loop frequency synthesiser indicates an 'out of lock' condition the signals into the phase comparator
2025-Full4082
It is noticed that a home made frequency synthesiser can briefly produce an output signal of unstable frequency when quickly tuning from from one end of an amateur band to the other. The probable reason is that
2025-Full479
With which part of the circuit of a transceiver is the term 'out of lock' associated?
2025-Full480
The term 'Out of lock' is a type of malfunction associated with a
2025-Full482
If a frequency synthesiser is 'out of lock', its output should be
2025-Full495
In a receiver, the difference between the maximum signal that can be received without overload and the minimum signal that can be discerned is the
2025-Full496
The dynamic range of a receiver is expressed in
2025-Full497
A receiver can just audibly detect signals of 0.4µV (Negative (-)145dBW) at its input. The receiver overloads at an input of 10mV (Negative (-)57dBW) causing intermodulation products that can be heard as false signals. The dynamic range of the receiver is
2025-Full508
A strong signal into the front end of a radio receiver exceeds its dynamic range. An effect of this will be
2025-Full509
Spurious signals in a receiver could be caused by
2025-Full7791
The dynamic range of a radio receiver is usually expressed in which units?
2025-Full3621
The IF stage has been omitted from the block diagram of a superhet receiver. At what point should it be inserted?
2025-Full3623
The block diagram shows a superhet receiver. G represents an audio amplifier. What is block F?
2025-Full3816
What is the main purpose of having two intermediate frequencies in a double superhet receiver?
2025-Full3944
In a double conversion super-heterodyne receiver, to which part of the circuit would you normally connect the BFO?
2025-Full505
A double superhet receiver designed to receive and demodulate SSB is likely to contain
2025-Full3425
To what frequency should the local oscillator 'X' be set to ensure successful operation?
2025-Full3628
A superhet receiver is tuned to 1.3555 MHz. The LO could also have been operating on
2025-Full3686
A superhet receiver is set to receive 1.820 MHz and the LO is running at a frequency of 1.355 MHz. An alternative frequency for the LO is
2025-Full515
In a superhet receiver the mixer
2025-Full516
The mixer combines the LO at 2MHz with the RF signal to produce an IF at 470kHz. The other principal output signal from the mixer will be on a frequency of
2025-Full517
A medium wave radio receiver to tune from 600kHz to 1600kHz and has an IF of 460kHz. The best choice of local oscillator frequency range will be
2025-Full512
A receiver is being designed to receive a medium wave broadcast on 1.000MHz. The local oscillator is set to 1.465MHz. For the same IF, what other frequency could the local oscillator be set to?
2025-Full513
An HF radio receiver is tuned to 1.85MHz and the IF is at 460kHz. The local oscillator will be at
2025-Full518
In a 14MHz superheterodyne receiver that has a 9MHz Intermediate Frequency the image frequency will be on
2025-Full520
A receiver tuned to the 7MHz amateur band, with a single IF of 455kHz, might suffer from second channel interference from stations around the frequency
2025-Full524
In a superheterodyne receiver a low Intermediate Frequency is an advantage because
2025-Full531
It is desired to achieve both a good image rejection and good adjacent channel selectivity in a radio receiver. This can be done by using a
2025-Full3629
Which curve in the drawing shows a critically-coupled response?
2025-Full532
An Intermediate Frequency transformer is said to be 'critically coupled' when it uses
2025-Full534
The selectivity of a superheterodyne receiver is determined mainly by the
2025-Full535
Reducing the gain of an IF amplifier stage by changing the bias has the side effect of causing distortion. This distortion is removed by
2025-Full536
The AGC voltage from the detector stage of a receiver varies the gain of the IF stages by
2025-Full537
In a typical IF amplifier the coupling between the stages is normally by means of
2025-Full7641
Phase noise is likely to be significant in the output from
2025-Full7643
What is the mechanism by which poor phase noise on an oscillator degrades transmitter performance?
2025-Full7693
The level of phase noise is normally given in units of
2025-Full7694
Phase noise is a feature often associated with
2025-Full7797
An important effect of severe phase noise in a transmitter is
2025-Full8031
Why does fitting an RF preamplifier to an HF receiver not necessarily result in being able to receive weaker signals?
2025-Full3626
A old UHF receiver has a quoted sensitivity on 0.32uV (Negative (-)117dBm) for 12 dB S/N. Overload is at 10mV (Negative (-)27dBm). To improve its sensitivity a pre-amplifier is inserted between the feeder and the receiver with a gain of 12dB and 8dB less internal noise. The dynamic range is
2025-Full3802
It is proposed to fit a pre-amplifier to an existing receiver. Which combination is likely to show the greatest overall improvement?
2025-Full7697
Locating an RF preamplifier at the antenna end of the feeder rather than the receiver end will typically improve the signal to noise ratio of weak signals by
2025-Full7698
It is often found that adding a preamplifier to an HF receiver has little effect on the signal to noise ratio of weak signals. Why might this be so?
2025-Full7900
A 70cm receiver has a long feeder to an antenna at the far end of the garden. To improve reception of weak signals a low-noise pre-amplifier is fitted alongside the receiver. The improvement in signal to noise ratio is noticeable but not impressive, certainly only a fraction of the expected improvement given the gain of the pre-amp. To try to further improve matters it is worth
2025-Full3633
What signals should be at the points 'P' and 'Q' in the drawing?
2025-Full540
Which of the following modes of modulation can a product detector resolve?
2025-Full543
Which mode of signals is demodulated with a ratio detector?
2025-Full7699
One advantage of a fast attack in the response of the AGC circuits is that
2025-Full7700
The AGC signal is derived from the
2025-Full7750
What does the term 'attack' refer to in the operation of the AGC in a receiver?
2025-Full7751
What does the term 'decay' refer to in the operation of the AGC of a receiver?
2025-Full7799
What settings might be provided to operate the AGC in a receiver?
2025-Full7901
In a superheterodyne receiver the AGC control voltage is usually the
2025-Full6022
Modulating a carrier with digital data can
2025-Full6023
The solid arrow in the phasor diagram represents the carrier and the dashed arrows represent sidebands. What type of modulation is being portrayed?
2025-Full6024
The solid arrow in the phasor diagram represents the carrier and the dashed arrows represent sidebands. What type of modulation is being portrayed?
2025-Full6027
The diagram shows a phasor diagram representing the positions occupied by a particular type of data modulation. In order to recover the data an SDR demodulator needs to
2025-Full7902
If the amplitude and phase of an incoming RF signal can be captured with reasonable accuracy
2025-Full8034
An oscillator is designed to have two outputs at the same frequency but with a phase difference of 90°. It is most likely that the oscillator is an essential part of
2025-Full8035
The drawing shows part of the block diagram of a radio device. It is likely to be an essential part of an
2025-Full6028
To capture both the amplitude and phase of a received signal in an SDR receiver it is necessary to
2025-Full6029
In order to use digital processing to tune to and demodulate a radio signal it is necessary to employ a mixing process where the incoming RF signals
2025-Full6030
Why is it necessary to utilise both an 'I' and a 'Q' signal when they are both derived from the same incoming signal?
2025-Full7800
An alternative to using local oscillators and mixers to extract the I and Q streams from an incoming radio signal is to
2025-Full554
In a modern transceiver which of the following would be shared between transmit and receive circuits?
2025-Full556
In a modern transceiver which of the following would NOT be shared between transmit and receive circuits?
2025-Full557
The RIT control on a radio transceiver
2025-Full558
The purpose of the RIT control on a transceiver is to
2025-Full559
When operating HF SSB in a net of several stations, it is noted that the stations are all transmitting on slightly different frequencies. A good way of improving reception is to adjust the
2025-Full700
A transceiver will often share circuits between transmitter and receiver. Typically this would include the
2025-Full3635
Which amateur band is the receive converter shown intended to cover?
2025-Full3636
The receive converter shown is designed to receive which amateur band?
2025-Full3637
Which amateur band will the receive converter cover?
2025-Full552
An HF operator who wishes to operate on UHF can do so by adding a
2025-Full553
In order to operate cross-band with VHF receive and HF transmit, an HF operator could use
2025-Full7905
It is desired to operate on 2m SSB using the station 10m, 28-30MHz, transceiver. This can be done with a suitable mixer and crystal oscillator. What is the best choice of crystal frequency?
2025-Full3659
The circuit is a
2025-Full3675
The diagram shows the circuit of an antenna tuning unit (ATU/AMU). When correctly adjusted it is intended to
2025-Full3737
The figure shows a half wave dipole fed from a transmitter. The dashed line represents the antenna's
2025-Full3738
The figure shows a half wave dipole fed from a transmitter. The dashed line represents the antenna's
2025-Full3739
A folded dipole has been used in a VHF directional antenna in order to
2025-Full3750
If an Antenna Matching Unit (AMU/ATU) is installed between the transmitter and the feeder to the antenna, and correctly adjusted it will
2025-Full3817
When used as intended, an antenna matching unit (AMU/ATU) is designed to reduce
2025-Full560
Due to the Velocity Factor, the physical length of antenna feeder is
2025-Full561
A length of coaxial cable with a polythene dielectric is cut to λ/4 at 10MHz. The physical length will be approximately
2025-Full562
The ratio of the wavelength of a signal in a coaxial cable to the wavelength in free space is a measure of the
2025-Full563
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
2025-Full565
An antenna has a feedpoint impedance of 100Ω at the frequency in use and is fed via 75Ω coaxial cable cut to λ/4 at the frequency in use. What impedance will the transmitter see?
2025-Full566
An antenna has a feed impedance of 100Ω. A λ/4 feeder to transform this to 50Ω will have an impedance of approximately
2025-Full570
Which of the following is NOT a type of balun?
2025-Full571
What would the advantage be fitting a 1 to 1 (1:1) balun to the centre of a dipole antenna of an amateur transceiver fed by coaxial cable?
2025-Full573
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
2025-Full574
Because of the end factor correction, the actual length of a λ/2 dipole antenna is approximately
2025-Full575
For a 30MHz half-wave dipole antenna, the length of wire on each side of the central insulator is approximately
2025-Full582
If the antenna shown was fed with a signal in the 14MHz band the feed-point impedance would be approximately
2025-Full583
The feed point impedance of a half-wave dipole antenna is between
2025-Full587
Placing passive conducting elements close to a dipole will affect the radiation pattern of the dipole to make it directional. It will also
2025-Full592
The sum of the forward and reverse signal voltages on a feeder, divided by their difference, is known as the
2025-Full594
If the forward signal on a feeder is 100V and the reflected signal is 10V the standing wave ratio is
2025-Full597
A suitable meter in a coaxial cable indicates that the voltage of the RF signal from the transmitter is 12V and the reflected signal voltage from the antenna is 2V. The SWR at that point is
2025-Full599
You are asked to choose between two antennas on the basis of the results of return loss measurements on each of them. Antenna 1 has a measured return loss of 10dB and antenna 2 has a measured return loss of 20dB. Which antenna should you choose?
2025-Full600
A transceiver is connected to a length of feeder of loss 3dB but the far end is left disconnected. A forward/reverse power meter reads 8W forward power. What will the reverse power reading be?
2025-Full601
A suitable meter in a coaxial cable indicates that the voltage of the RF signal from the transmitter is 10V and the reflected signal voltage from the antenna is 1V. The Return Loss is
2025-Full602
A transmitter feeds an antenna using a short length of good quality coaxial cable but the matching between the cable and the antenna is very poor. The transmitter will 'see'
2025-Full603
A transmitter is feeding a length of coaxial cable connected to an antenna, which is poorly matched. Rain seeping into the cable increases its attenuation by some 6dB. The effect at the transmitter will be that the SWR
2025-Full604
The return loss of an antenna is noted as being 16dB. When installed the feeder is 10 metres long. If the feeder has a loss of 0.2dB/metre, the expected return loss, measured at the transmitter, will now be
2025-Full607
If RF losses in a feeder are high the SWR measured at the transmitter will be
2025-Full608
The return loss of a feeder and antenna is measured as 30dB. If the feeder has a loss of 3dB, the return loss of the antenna is
2025-Full609
The return loss of an antenna is measured as 20dB. The antenna is installed using 10m of feeder, which has a loss of 0.5dB per metre. The return loss measured at the transmitter will be
2025-Full610
A transmitter is connected to a length of feeder of loss 3dB and an antenna with a return loss of 15dB. What return loss will be seen at the transmitter
2025-Full718
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
2025-Full719
It is desired to match an antenna of 100Ω impedance to a transmitter of 50Ω output using a short length of 72Ω feeder as an impedance transformer. Its length should be
2025-Full720
A 100Ω antenna is feeding a receiver with a 50Ω input impedance. It is decided to improve the matching by inserting a λ/4 length of coaxial cable as an impedance transformer. The characteristic impedance of this cable should be
2025-Full746
Two 50Ω Yagi antennas are connected by a λ/4 splitter to match 50Ω feeder. The characteristic impedance of the two λ/4 sections should be about
2025-Full7908
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
2025-Full7911
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?
2025-Full7914
How long is a typical half wave dipole tuned for the centre of the 1.8MHz band?
2025-Full7916
How long is the optimum length of a half-wave dipole for the centre of the 3.5MHz - 3.8MHz band?
2025-Full7917
A directional power meter shows 400W from the transmitter and 25W reflected from the antenna. An SWR meter is then substituted for the power meter. What approximate reading is expected?
2025-Full7918
A Radio Amateur wants help with their antenna matching. If the forward power to an antenna and feeder is 9W and the reflected power is 1W then the SWR is approximately
2025-Full7919
A directional power meter shows 400W from the transmitter and 25W reflected from the antenna. The Return Loss is
2025-Full7920
A Radio Amateur wants help with their antenna matching. The power meter shows 9W from the transmitter and 1W reflected. What is the Return Loss?
2025-Full7922
Four Yagis are connected together to give increased gain. Each has a feed impedance of 50Ω and have λ/4 tails of 75Ω coax to a common point where they are all paralleled together. Another λ/4 length is used to match to the 50Ω main feeder. What characteristic impedance is ideally needed?
2025-Full825
The diagram shows
2025-Full829
The diagram below shows
2025-Full849
The diagram shows
2025-Full3673
Which drawing correctly shows an electromagnetic wave?
2025-Full3806
Why is circular polarisation advantageous when communicating through or with a satellite?
2025-Full617
Circular polarisation is characterised by the electric and magnetic fields
2025-Full782
When an antenna is using right-handed circular polarisation
2025-Full852
When using circular polarisation The E and H fields of an electromagnetic wave are:-
2025-Full3674
Which statement about antenna polarisation offers the best advice?
2025-Full3730
If the distance between transmitting and receiving antennas in free space is doubled, the power flux density at the receiving antenna changes by
2025-Full3732
Under 'free space conditions' electromagnetic waves travel according to an inverse square law of power flux density. Such a statement means that the power flux density
2025-Full3760
Under free space conditions electromagnetic waves
2025-Full3797
The Maximum Usable Frequency (MUF)
2025-Full6031
A higher sunspot number is often an indication of
2025-Full6032
What effect does the presence of sunspots have on HF propagation?
2025-Full6033
A Dellinger fade-out or Sudden Ionospheric Disturbance is normally associated with
2025-Full6035
The Critical Frequency
2025-Full6036
The mode of propagation known as NVIS is normally used for
2025-Full6037
NVIS contacts are usually possible
2025-Full6039
The polarisation of HF antennas is of lesser concern than VHF and UHF antennas because
2025-Full6040
A feature of EME propagation is
2025-Full6042
Auroral propagation
2025-Full6043
An amateur in the Orkney isles north of the Scottish mainland is in VHF contact with an amateur in Tromso in Northern Norway. There is a rapid flutter on the signal. This is typical of
2025-Full6044
The rapid fluttering typical of VHF auroral contacts is caused by
2025-Full620
The electric field strength of radio frequency electromagnetic radiation is measured in
2025-Full624
At a distance from a transmitter the power flux density (PFD) is 1W/m² and the electric field strength (FS) is approximately 20V/m. At twice that distance the PFD is
2025-Full627
When travelling away from a transmitter on clear ground, it is noted that the field strength has halved. The power flux density can be expected to
2025-Full648
The Critical Frequency is the
2025-Full650
The Critical Frequency will
2025-Full652
The maximum usable frequency (MUF) undergoes both daily and annual changes. The lowest MUF over a particular path normally occurs in the
2025-Full653
During the summer the
2025-Full7752
Which one of the items below SHOULD NOT be included when calculating a link budget?
2025-Full7758
The polarisation of an HF antenna is less significant than VHF or UHF antennas because
2025-Full7802
What effect does the presence of sunspots have on HF propagation?
2025-Full7805
The mode of propagation known as NVIS is normally used for
2025-Full7810
A large solar flare will
2025-Full7811
An ionospheric fade-out or Sudden Ionospheric Disturbance is normally caused by
2025-Full7812
The polarisation of HF antennas is less of a concern than VHF and UHF antennas because
2025-Full7818
Galactic noise is
2025-Full7925
It is noticed that on 2m switching from a vertical to horizontal antenna causes a loss of signal of almost 20dB. However, on a long-distance HF contact it makes relatively little difference. This is probably because
2025-Full7926
What is the basis of auroral propagation?
2025-Full8122
Which factor is likely to affect a UHF link budget
2025-Full8123
Which action could be employed to optimise a wireless link budget?
2025-Full8037
A PC network in a house has been installed using unscreened cable rather than screened cable. A likely outcome is that
2025-Full8038
Checks show that the outer braid of the TV down-lead is not continuous from the loft mounted aerial to the TV socket in the lounge. A likely effect of this is that
2025-Full8039
To simplify the installation of an alarm system a single wire is run from the control unit through each sensor in series round the house and then back to the control unit. A risk with this approach is that
2025-Full8040
An amateur is offering a home designed transceiver for sale at an amateur rally. That means that the
2025-Full8041
The Federation of Communication Services (FCS) is responsible for
2025-Full240
The first action in dealing with an EMC complaint should be to
2025-Full242
If a neighbour calls with a list of dates and times when his TV picture has appeared distorted, the first action a licensed amateur should take is to
2025-Full243
If a neighbour rebuffs all attempts to help resolve a problem of breakthrough on his CD player, the radio amateur should advise them to get in touch with
2025-Full246
What is the best thing for you to do when a neighbour complains of interference to television reception?
2025-Full249
The installation instructions for a mobile transceiver state that the positive connection should be made direct to the car battery, via a suitable fuse. Why should the connection be direct to the battery?
2025-Full250
Powering a transmitter in a car, via the cigarette lighter (accessory) socket is
2025-Full251
The car handbook states that transmitters over 50W power must not be fitted. Why might this be?
2025-Full253
Which of the following antenna systems is least likely to cause EMC problems?
2025-Full254
When planning a horizontal dipole antenna system you should ensure that
2025-Full256
A station on the 144 to 145MHz band has an ERP of 25W. What is the RF field strength at a distance of 50m from the antenna?
2025-Full257
On 433.5MHz with an ERP of 225W, what is the RF field strength at a distance of 50m from the antenna?
2025-Full263
If a domestic TV is suffering interference from a nearby VHF amateur station, which of the following filters inserted in the TV down lead would improve its EMC immunity
2025-Full264
A 400-800MHz band pass filter inserted in a TV downlead will improve the EMC immunity by attenuating signals
2025-Full267
Which of the following could be used to attenuate a specific unwanted frequency?
2025-Full277
Ferrite beads are often slipped onto internal DC supply leads in order to
2025-Full284
Winding two-core power supply cables around ferrite rings reduces EMC problems because
2025-Full293
A mains filter suitable for use in an amateur transmitting station should be designed to
2025-Full298
Which one of the following would be used to reduce RF energy from a transmitter entering the public mains supply?
2025-Full316
Which of the following precautions is likely to reduce passive inter-modulation products?
2025-Full317
Which of the following are likely to reduce the generation of passive inter-modulation products at your station?
1. Including a low pass filter (LPF) in your station. 2. Including a high pass filter (HPF) in your station. 3. Ensuring all antenna joints and connections are clean and not corroded. 4. Changing old metal guttering for plastic guttering.
2025-Full320
Which of the following signals may be generated by corroded contacts on an antenna?
2025-Full342
Passive Inter-modulation Products are often caused by
2025-Full343
The PN junction in a semiconductor device can be the cause of breakthrough problems by
2025-Full345
Unwanted RF can cause problems in semiconductor equipment by
2025-Full346
The easiest way to determine if breakthrough to a receiver is caused by pick up on its loudspeaker leads is to see whether the problem still exists when the
2025-Full355
Masthead pre-amplifiers used in broadcast TV reception systems can suffer from
2025-Full356
Masthead pre-amplifiers intended to improve analogue TV broadcast reception can reduce immunity to amateur transmissions because they amplify
2025-Full357
If an amateur's HF transmission enters a TV system via a masthead pre-amplifier the breakthrough is likely to be caused by
2025-Full358
Cross modulation in a broadcast TV receiver system is most likely to be caused by
2025-Full360
'Blocking' is an effect associated with
2025-Full362
The form of breakthrough known as 'desensitisation' in a receiver occurs when
2025-Full363
If the gain of a receiver varies in time with the audio of an unwanted SSB signal, the problem is known as
2025-Full364
If an FM transmission causes the picture of a TV receiver to disappear, this form of breakthrough is called
2025-Full367
Receiver blocking or desensitising may be caused by
2025-Full3677
A medium wave domestic receiver is experiencing an interference that sounds a bit like someone talking although no actual words can be heard. It is likely that the receiver is suffering from
2025-Full3678
The circuit shown is that of a
2025-Full369
UK TV broadcast stations use the frequency band
2025-Full370
The Intermediate Frequency of a medium wave broadcast radio receiver is likely to be between
2025-Full373
Image interference is the likely cause of interference from
2025-Full3803
What is the main reason for setting the transmit power to the minimum required to maintain contact?
2025-Full3804
Your contact reports your signals as 40 over 9. It is advisable to
2025-Full3805
Why is it recommended that your transmit power is reduced to no more that that required to maintain the contact?
2025-Full3826
Which of the following features of many domestic television mast-head amplifiers makes them particularly susceptible to suffer cross-modulation and overload from high-power amateur transmissions?
2025-Full388
Signals from a transmitter working on 3.56MHz are reported as causing interference over the whole of the FM broadcast radio band. This is probably caused by a harmonic of the RF signal getting into the
2025-Full3930
What Electromagnetic (EMC) safety precautions are essential when installing amateur radio equipment in a motor vehicle?
2025-Full3960
Interference to a mains powered domestic FM radio receiver appears to be independent of the exact frequency to which the receiver is tuned but is only heard when the receiver is tuned to a broadcast signal. A reasonable conclusion is that the interfering signal is
2025-Full3995
A local VHF paging transmitter in the 160MHz band is occasionally breaking in to a fairly weak broadcast VHF FM signal. It is decided to try using a filter on the aerial lead to the VHF FM receiver. Which filter will be most suitable?
2025-Full4064
A domestic VHF FM radio receiver is noticeably more sensitive to interference from a neighbour's HF transmitter when on the 3.5MHz band than on other HF bands. This is likely to be due to
2025-Full4065
An EMC consideration when planning an end-fed antenna rather than a dipole or a centre-fed antenna is that
2025-Full4086
A mains filter suitable for use on a mains powered HF transmitter will be of a
2025-Full6046
An alarm system meets the various standards including EMC. However it is found to react to a neighbour's radio transmissions on several HF bands. Why might that be?
2025-Full6048
What standards are home designed amateur transmitters expected to comply with?
2025-Full6049
If a commercial transceiver is modified to operate on amateur bands the equipment must then comply with
2025-Full6050
It is noticed that when a clock radio and a mobile phone are placed on the same bedside cabinet, there are regular bursts of noise from the clock radio. This is
2025-Full6051
An amateur is dealing with a complaint from a neighbour but the timing of the complaint does not coincide with her times of operating. Further investigation suggests the times coincide with the time of arrival home from school. A new avenue of investigation should be
2025-Full6052
An amateur has modified a CB antenna to form a good quarter wave vertical on the ten metre band. The vertical is mounted on the roof of the conservatory which is on the back of the house. The amateur should
2025-Full6053
A quarter wave vertical antenna installed without an RF earth and connected to a transmitter is likely to cause?
2025-Full6078
If a neighbour complains that you are causing them interference then you should
2025-Full6079
When installing amateur radio equipment in a vehicle
2025-Full708
Cross modulation is an effect that occurs when
2025-Full733
A 2 metre amateur transceiver is operated in a room containing a television, a music centre, a lap-top computer and a mechanical central heating thermostat. The transceiver antenna is a dipole temporarily hung in the room. Which item is LEAST likely to be affected?
2025-Full734
Which mode of transmission is most likely to result in the Amateurs voice being heard on a neighbour's audio hi-fi system?
2025-Full735
When an amateur station is operated on 14MHz SSB a nearby television receiver produces an audio output, the level of which is not affected by the volume control setting. Where is the most probable point of entry of the signal?
2025-Full7711
Radio amateurs
2025-Full7712
Advice for radio amateurs on mobile installations is in the
2025-Full7754
The Federation of Communication Services issues a Code of Practice which gives
2025-Full7755
Which UK body provides guidance on installing radio equipment in vehicles?
2025-Full7820
A neighbour has a new TV installed. They are suffering occasional instances of interference, possibly RF. It would be sensible to check if the
2025-Full7824
An amateur has a quarter wave vertical on the ten metre band. The vertical is mounted on the roof of the conservatory. The amateur should
2025-Full7825
The most significant EMC risk in using a quarter wave vertical antenna without an RF earth is
2025-Full7931
A home made transceiver must comply with the
2025-Full7936
Where might one of the devices shown be used?
2025-Full7943
General guidance on fitting transmitting equipment in vehicles can be found in the
2025-Full8042
What does operating split mean?
2025-Full8043
Your SSB contact on 7.063MHz is in the SSB segment of the band plan but is constantly interrupted by a CW contact from two stations in a different ITU Region. That may be because
2025-Full8052
Many UK amateurs can be heard contacting a station in a country with which communications is normally possible. However, you cannot hear the distant station. A reason for this may be that
2025-Full8083
When on a ship in international waters between Australia and New Zealand the frequencies allocated to amateur radio may be found in
2025-Full8084
The American continent is classified as
2025-Full8085
The ITU Radio Regulations
2025-Full3764
You decide to take your amateur radio equipment with you on a round the world cruise. To know which frequencies you can use in international waters you should refer to
2025-Full3855
An amateur holding the callsign M0XYZ has permanently moved to Portugal, which has implemented CEPT Recommendation T/R 61-01. M0XYZ can
2025-Full3856
An amateur holding the callsign MJ0JKL has permanently moved to Italy, which has implemented CEPT Recommendation T/R 61-01. MJ0JKL can
2025-Full3857
If operating in Switzerland under a reciprocal licence, operation must comply with
2025-Full41
Which frequencies are available to a UK full licensed station on a vessel in international waters?
2025-Full6068
When planning an international event using only set segments of the amateur bands, to minimise disruption to normal amateur activity you should remember that
2025-Full6070
Beacons in the 5MHz band are likely to be found
2025-Full6071
Often the frequency of a data signal is specified by its nominal carrier frequency. A risk with this approach, particularly in the 5.4035MHz sub-band is
2025-Full6072
One of the 5MHz sub-bands is 10kHz wide. This will allow
2025-Full6073
5MHz NVIS contacts within the UK should avoid the
2025-Full6075
Operating 'split' frequency might be considered if
2025-Full6076
The rare island station you are trying to contact often says 'receiving five down'. This means that
2025-Full6077
The purpose of operating split frequency is to
2025-Full73
How often is it advisable to test transmissions for radiation of harmonics and other spurious emissions?
2025-Full741
The holder of a Full Amateur Radio Licence can operate under their licence in which ONE of the following?
2025-Full742
When operating temporarily in a European country under T/R 61-01, the rules applicable to amateur radio are those
2025-Full743
To operate abroad under CEPT recommendation T/R 61-01 you must operate
2025-Full7946
You are operating from a rare and sought after location but are swamped by requests for a contact such that you cannot identify any incoming callsigns and your replies are similarly swamped. The accepted practice to resolve this situation is to
2025-Full7947
The recommended maximum bandwidth on 473.5kHz is
2025-Full7949
When operating in other countries you should note that
2025-Full8086
When calling CQ for amateurs in other countries you should note that
2025-Full8104
When operating in other countries, one point to remember is that
2025-Full174
In a house with Protective Multiple Earthing, the house mains earth and the neutral are
2025-Full176
Amateur radio masts and antennas in exposed high locations need to be protected against
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Thunder storms are a risk to an amateur station because
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For a licensed radio amateur, using a hand-held microphone whilst driving a moving vehicle is, in itself
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Before transmitting from a temporary location it is most advisable to check
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When operating a station in an outdoor location an amateur should
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When operating your station in an outdoor location which one of the following precautions is most appropriate to protect you from danger from overhead power lines?
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Mains powered equipment presents a higher risk to safety mainly because
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If it is unavoidable to make adjustments to live high voltage equipment while it is switched on, the operator should
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In a domestic Protective Multiple Earth (PME) electrical system
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Where a number of properties are supplied by a Protective Multiple Earth (PME) electrical system, in the event of neutral fault conditions in the electrical supply system
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A possible consequence of installing an RF earth rod alongside a PME mains electricity supply is that under some fault conditions
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A lightning strike can occur when
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You have finished operating at the end of the day and you are aware that there is a strong possibility of thunder storms. You should:
2025-Full4099
Which of the following statements concerning the protection of an amateur radio station from a direct lightning strike is true?
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The purpose of conducting a risk assessment is to
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When seeking insurance cover for an event open to the public the insurers will likely expect
2025-Full6066
To ensure a public amateur radio demonstration does not cause RF fields above a safe level you should check the guidance provided by the
2025-Full6067
ICNIRP provide information and guidance on
2025-Full755
A significant risk in a motor vehicle, not normally a problem in a house, is
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Unless the instruction expressly permits, you should NOT
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The purpose of the ICNIRP limits is to
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What important action or check has not been performed in planning this outdoor operating trip?
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When planning to take UK mains powered equipment overseas, it is necessary to check
2025-Full7956
A risk assessment should be carried out
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When operating outdoors with power from an electrical generator, fire extinguishers should be stored
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When operating outdoors with power from an electrical generator, the fuel should be stored
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You hold a Radio Club event where a Third Party lodges a claim for an injury. Your Insurance Company is likely to ask you for a copy of
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Care should be taken when working on mains powered equipment because
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A sensible safety precaution when working on live equipment is to ensure that
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What is the level of the second harmonic expressed in units of dBc?
2025-Full8045
What is the level of the third harmonic expressed in units of dBc?
2025-Full8046
The RF noise extends across the spectrum as shown but may not be noticeable where there is a stronger signal. What, approximately, is the RF signal to noise ratio of the signal at 1.8MHz?
2025-Full8047
A voltmeter comprises a microammeter and a series 'multiplier' resistor of 100kΩ. The reading between points A and C is 9V. Between A and B it is 3V and between B and C it is 3V. What are the two unknown components?
2025-Full140
The power output of a piece of equipment is specified in Peak Envelope Power. What type of output is this?
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Peak envelope power (PEP) is the power
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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
2025-Full161
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?
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The accuracy of a digital frequency counter is determined by the
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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
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An analogue meter with a Full Scale Deflection of 50µA can be converted to a voltmeter with a Full Scale Deflection of 5V by adding a
2025-Full287
If the value of a capacitor is found to increase as the temperature of the circuit increases it is said to have
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A capacitor whose value decreases as temperature increases has a
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A crystal is used inside a temperature controlled oven. The purpose of the oven is to
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A receiver is quoted as having a signal to noise ratio of 10dB with 0.2mV at its input. This is tested and a 0.2mV RF input signal modulated with a single tone gives, 1W of audio power at the loudspeaker, accompanied by an audio background noise of approximately
2025-Full336
A long length of feeder is connected to a transmitter producing 100W. The loss in the feeder is 6dB. This is connected to antenna of gain 10dB. The effective radiated power (erp) is approximately
2025-Full337
The unit dBm is often used to express power with respect to1mW; that is 0dBm=1mW. What power is 20dBm?
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A meter connected between point A and earth will indicate
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An air cored inductor has a positive temperature coefficient of inductance. Capacitors can be obtained with either positive or negative temperature coefficients. The combined temperature coefficient of the capacitors in a tuned circuit should be
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The sensitivity of a receiver is being checked. The RF signal generator will only go down to 20µV so an attenuator giving 2µV is fitted. That is an attenuation of
2025-Full3614
A 1 to 30MHz HF transmitter is checked against a very accurate off-air frequency standard to within 100Hz. The specification of the transmitter crystal oscillator is 0.1ppm per degree C and an ageing drift of 5ppm per year. The room and crystal temperature vary by up to 10 degrees. The earliest that the transmitter may be outside its 500Hz accuracy specification will be during
2025-Full3647
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?
2025-Full3655
What device is shown in the circuit diagram?
2025-Full3656
In the device shown the switch would be labelled
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In the circuit below the battery supplies 12 Volts and R1 and R2 are both 100kOhms. Which combined internal resistance and multiplier resistor in the voltmeter will have the LEAST effect on the circuit being tested?
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When making voltage measurements with an analogue volt-meter, you suspect that the meter may be affecting the operation of the circuit. A simple way of checking this is to:
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In the diagram below, the two meters are used to indicate
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In the diagram below, what are the two meters used to measure?
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The circuit below shows
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What will be the maximum frequency error of the 7th harmonic of a 10MHz crystal calibrator when it has been adjusted using a frequency counter which has a clock accuracy of 3ppm?
2025-Full3926
A 10MHz quartz crystal oscillator is understood to have a negative frequency drift of 2ppm/year. What would you expect its frequency to be, 3 years after calibration?
2025-Full3927
You wish to transmit a 3kHz wide, USB signal on the 17m band (18.068 MHz to 18.168 MHz) using a transmitter that is fitted with a free running Variable Frequency Oscillator (VFO). The VFO frequency is known to drift upwards at 850Hz/hr. What is the highest dial frequency you could use for 2hr whilst being sure you are still operating within band?
2025-Full4005
The drawing shows an ammeter circuit used to monitor the current in a power supply. The variable resistor has a maximum value of about 10% of the resistance of the meter movement and is used for calibration. Modifications have increased the supply from a maximum of 2A to 5A and the meter circuit needs to be modified accordingly. What change is needed to accomplish this?
2025-Full4006
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?
2025-Full4007
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?
2025-Full4025
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?
2025-Full4038
A frequency counter has a 10MHz oscillator known to be accurate to 100 parts per million and this has been used to measure the carrier frequency of an FM transmission. The transmission bandwidth is 10kHz. What is the highest dial frequency that the operator may set on the 28MHz band to be confident that their signals remain within the allowed amateur band?
2025-Full4039
A frequency counter is used to measure the frequency of a very accurate 10MHz oscillator and the readout says 9.999000MHz. This counter is then used to measure the frequency of a 2m transmitter and it reads 144.300000MHz. What is the frequency of the transmitter?
2025-Full6055
A crystal oscillating at 8100kHz has a temperature coefficient of -23ppm per degreeC. It was accurately calibrated at 20°C. What is the frequency of oscillation at 65°C?
2025-Full6058
Which control should be adjusted to show the sidebands of an amplitude modulated signal more clearly?
2025-Full6060
What is the level of the second harmonic of the 1.8MHz transmission?
2025-Full6061
What is the level of the third harmonic of the 1.8MHz transmission?
2025-Full6063
An RF signal generator has a 50Ω output impedance and is able to produce signals up to 1V rms. The output is adjusted using a high impedance oscilloscope to display a trace of 283mV peak to peak. The oscilloscope is disconnected and the sig gen is then connected to a 20dB attenuator to a receiver which displays the rms signal voltage at its input. What reading is expected?
2025-Full7644
A home made transmitter uses a crystal at 3.5MHz multiplied up to 28MHz. The crystal is specified as 0.5ppm per degree C. At switch on the room is at 18C but inside the transmitter case is 36C when warmed up. By how much will the transmitted frequency vary in that time?
2025-Full7964
An RF amplifier is required to bring the 200mV output from an oscillator up to 4V to drive the output transistors in a transmitter. How much gain will you need?
2025-Full7965
An RF preamplifier is required to bring the 0.2µV signal from the antenna to the 8µV required by the main receiver for best noise performance. What is the preamplifier gain?
2025-Full7997
An oscilloscope is being used with a half-wave dipole antenna to monitor a received signal. The trace shows 282mV peak-to-peak. However when you also connect this assembly to your radio receiver it shows 6dB lower. Why?
2025-Full830
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?
2025-Full833
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?
