Advanced trial exam

  1. What is the current flowing through a 24 ohm resistor connected across 240 volts?
    1. 24,000 amperes
    2. 0.1 amperes
    3. 10 amperes
    4. 216 amperes
  2. The ends of a half-wave dipole the
    1. voltage and current are both high
    2. voltage is high and current is low
    3. voltage and current are both low
    4. voltage low and current is high
  3. The velocity factor of a coaxial cable with solid polythene dielectric is about
    1. 0.66
    2. 0.1
    3. 0.8
    4. 1.0
  4. To convert nanofarads to picofarads requires
    1. multiplication by 1,000
    2. division by 1,000
    3. multiplication by 10,000
    4. division by 10,000
  5. A variation in received signal strength caused by slowly changing differences in path lengths is called
    1. absorption
    2. fading
    3. fluctuation
    4. path loss
  6. Two 20 uH inductances are connected in series. The total inductance is
    1. 10 uH
    2. 20 uH
    3. 40 uH
    4. 80 uH
  7. A transistor with 5v across it and 10mA of flowing through it will be dissipating
    1. 50mW
    2. 50W
    3. 5W
    4. 5mW
  8. The level of ionisation in the upper atmosphere relies on the
    1. mixing effect of hot and cold air
    2. earth's magnetic field
    3. solar radiation
    4. all of the aboven
  9. The practical efficiency of a Class 'A' amplifier is approximately
    1. 20-40%
    2. 80-95%
    3. 50-70%
    4. 90-100%
  10. Two FM signals transmit on the same frequency but only one is heard due to the
    1. capture effect
    2. modulation index
    3. de-emphasis
    4. pre-emphasis
  11. For a circuit to oscillate it requires
    1. appropriate CTCSS encoding
    2. positive feedback
    3. negative feedback
    4. suppression of filtering
  12. The main purpose of an automatic level control (ALC) circuit in an SSB transmitter is to
    1. compress peaks of audio input
    2. prevent the power amplifier being driven into non-linearity
    3. measure the transmitter's output voltage
    4. give a meter indication of speech input level
  13. For a given frequency, the physical length of half-wave dipole antenna
    1. needs to becomes longer as the frequency increases
    2. has no relation to the frequency
    3. needs to be shortened as the frequency increase
    4. should be shortened as the frequency decreases
  14. A requirement of using low-level AM modulation of a transmitter is
    1. modulator to be biased in Class C
    2. to modulate the final (PA) stage
    3. all stages to be Class C amplifiers
    4. all stages after modulation are linear
  15. The signal from a frequency modulated transmitter has
    1. an amplitude which varies with the modulating waveform
    2. a frequency which varies with the modulating waveform
    3. a single sideband
    4. no sidebands
  16. The correct colour coding for the neutral wire in a flexible mains lead is
    1. brown
    2. blue
    3. yellow and green
    4. white
  17. In the circuit diagram shown the PIV across each diode is
    1. 7.07 volts
    2. 28.28 volts
    3. 40 volts
    4. 40.48 volts
  18. The impedance at the feed point of a folded dipole antenna is approximately
    1. 300 ohm
    2. 150 ohm
    3. 75 ohm
    4. 100 ohm
  19. In a bipolar transistor the base-emitter junction must be
    1. reverse biased
    2. forward biased
    3. unbiased
    4. alternating forward and reverse
  20. In a transformer carrying an AC current the field of the energised winding generates a signal in another winding of the device by means of
    1. eddy currents
    2. mutual induction
    3. polling magnetism
    4. hysteresis
  21. The function of a buffer amplifier is to
    1. increase the power level significantly
    2. reduce loading effects on the previous stage
    3. store energy until required
    4. provide power supply regulation
  22. This filter circuit is that of a
    1. high pass filter
    2. band pass filter
    3. notch filter
    4. low pass filter
  23. The bandwidth of a typical SSB transmission on the HF amateur bands is
    1. 1.2 KHz
    2. 3.0 KHz
    3. 5.5 KHz
    4. 9.0 KHz
  24. A varactor diode acts like a variable
    1. resistance
    2. voltage regulator
    3. inductance
    4. capacitance
  25. In frequency modulation the term modulation index refers to the
    1. amount of frequency shift each side of the unmodulated carrier frequency
    2. ratio of the frequency deviation to the frequency of the modulating wave
    3. level of effective radiated power
    4. ratio of the highest frequency to the frequency of deviation
  26. In this audio amplifier C3 acts as a
    1. low-pass filter element
    2. coupling capacitor
    3. bypass capacitor
    4. high-pass filter element
  27. A sine-wave alternating current of 10 ampere peak has an RMS value of
    1. 5 amperes
    2. 7.07 amperes
    3. 14.14 amperes
    4. 20 amperes
  28. The receiver stage most likely to have selective filters is
    1. RF amplifier
    2. IF amplifier
    3. AF amplifier
    4. Buffer amplifier
  29. A superhet receiver for SSB reception has an insertion oscillator to
    1. replace the suppressed carrier for detection
    2. phase out the unwanted sideband signal
    3. reduce the passband of the IF stages
    4. beat with the received carrier to produce the other sideband
  30. A band-stop filter will
    1. pass frequencies each side of a band
    2. stop frequencies each side of a band
    3. stop frequencies above a certain value
    4. stop frequencies below a certain value
  31. A suitable meter used to measure antenna impedance is
    1. reflectometer
    2. wave meter
    3. noise bridge
    4. deviation meter
  32. Image interference in a superhet receiver results from an unwanted signal on
    1. twice the frequency to which the receiver is tuned
    2. twice the intermediate frequency away from the desired signal
    3. the same frequency as the local oscillator
    4. half the frequency to which the receiver is tuned
  33. The most likely cause of parasitic oscillations in a transmitter is
    1. rectification in a modulator
    2. carrier oscillator variations
    3. stray circuit inductance and capacitance
    4. negative feedback
  34. In this block diagram of a phase locked loop the voltage controlled oscillator is stage number
    1. 1
    2. 2
    3. 3
    4. 4
  35. The ratio of inductive reactance to the effective resistance of a coil is called
    1. self-inductance
    2. mutual inductance
    3. coefficient of coupling
    4. Q
  36. A gain in power of 30 dB is the same as a power ratio of
    1. 10
    2. 100
    3. 1,000
    4. 10,000
  37. Capacitive top loading or a 'capacity hat' on a vertical antenna will
    1. decrease the electrical length
    2. dramatically increase its bandwidth
    3. improve its RF power rating
    4. increase the electrical length
  38. The distance from the far end of the ground wave to the nearest point where the sky wave returns to the earth is called the
    1. skip distance
    2. radiation distance
    3. skip angle
    4. skip zone
  39. Transmitter power amplifiers can generate parasitic oscillations on
    1. the transmitter's output frequency
    2. harmonics of the transmitter's output frequency
    3. frequencies unrelated to the transmitter's output frequency
    4. VHF frequencies only
  40. A correct detector for FM signals is a
    1. product detector
    2. discriminator
    3. balanced modulator
    4. filtered loop detector
  41. Tropospheric ducting long distance propagation normally occurs
    1. below 3MHz
    2. above 30MHz
    3. below 30Mhz
    4. on all amateur bands
  42. A transformer with 100 turns on the primary winding and 10 turns on the secondary winding is connected to 230 volt AC mains. The voltage across the secondary is
    1. 10 volts
    2. 23 volt
    3. 110 volts
    4. 2300 volts
  43. Radio wave polarisation is defined by the orientation of the radiated
    1. magnetic field
    2. electric field
    3. inductive field
    4. capacitive field
  44. When distortion occurs in a non-linear device driven by a signal comprising more than one frequency this is called
    1. phase distortion
    2. harmonic distortion
    3. intermodulation distortion
    4. linearity resultant distortion
  45. Small ferrite beads are sometimes threaded over the input leads of transistors in RF amplifiers in order to
    1. reduce the noise level
    2. tune the amplifier
    3. neutralise the amplifier
    4. suppress parasitic oscillation
  46. The dynamic range of a receiver is the
    1. ability to produce high fidelity audio through its speaker
    2. level at which powerful signals begin to have distortion
    3. difference between the minimum discernible signal and the maximum signal without overload
    4. selectivity of a wanted signal without adjacent channel interference
  47. The sensitivity of a multi-meter is expressed in terms o
    1. decibels per scale
    2. ohms per volt
    3. full scale deflection
    4. display or needle movement damping factor
  48. The duty cycle of an amateur RTTY transmission is
    1. 50%
    2. 10
    3. 1
    4. 100
  49. The purpose of a balun in a transmitting antenna system is to
    1. protect the antenna system from lightning strikes
    2. balance harmonic radiation
    3. reduce unbalanced standing waves
    4. match unbalanced and balanced transmission lines
  50. The hfe or beta of a transistor is its
    1. breakdown voltage
    2. current gain
    3. switching rate
    4. maximum operating temperature