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Standard trial exam
The distance from a transmitter to the point where the signal first returns after refraction from the ionosphere is called
multi hop
skip zone
skip distance
ionosphere prediction distance
To prevent radiation of radiofrequency signals when a transmitter is being tested continuously, you should use
a transmission line
an artificial antenna
an indoor antenna
a standing wave ratio (SWR) meter
A correctly operated Standard transmitter causes severe interference to one television set in close proximity but not to others in the same location. The problem is probably due to
harmonic radiation
front-end overload of the television set
cross-modulation with an "off air" broadcast transmitter
radiation of parasitics
The approximate length of a half wave dipole antenna for 21MHz is
15 metres
0.75 metres
7.5 metres
2.5 metres
What can occur when a single-sideband signal is amplified by a nonlinear amplifier?
lower amplifier efficiency
increased readability
elimination of unwanted sideband
distortion
What does the term "receiver overload" mean?
Interference caused by overcrowding of the band
Interference caused by a strong signal from a nearby transmitter
Interference caused by adjusting the receiver volume too high
Interference caused by transmitter harmonics
Ionisation in the ionosphere is caused primarily by the
magnetic effect and axial rotation of the earth
magnetic effect of the sun
ultraviolet and other radiation from the sun
rotation of the moon
The function of a tripler stage in a transmitter is to
multiply the frequency of the incoming signal by three
triple the power output
enable two final stages to be fed by the one oscillator
act as an impedance doubling device
The input impedance of a Field Effect Transistor (FET) is
very high
very low
current dependant
voltage dependant
The ratio of the collector current Ic to the base current Ib of a transistor is called
resistance gain
voltage gain
power gain
current gain
The feed impedance of a centre fed half wave dipole is free space is
300 ohms
50 ohms
72 ohms
32 ohms
The standing wave ratio (SWR) on a transmission line is related to the
voltage at the ends of the antenna and the voltage at the feed point
maximum voltage and the maximum current in the antenna
power fed to the antenna and the power reflected back from the antenna
maximum voltage and the maximum current in the transmission line
This diagram shows the circuit of
a full wave rectifier
a half wave rectifier
an oscillator
a detector
The ability of a communications receiver to distinguish between signals that are close in frequency is known as its
selectivity
sensitivity
stability
bandspread
The zener doide in this diagram
is reversed biased
is forward biased
has positive voltage applied to its anode
is not conducting
Operation of the Receiver Increment Tuning (clarifier) control in a SSB transceiver
increases the selectivity of the receiver
adjusts the receiver gain in small steps
varies the sensitivity of the receiver
provides a small variation of receiver tuning
For a moving coil meter to measure resistance which additional components would have to be used?
battery and diode
resistor and capacitor
capacitor and battery
battery and resistor
The ability of a receiver to distinguish between signals that are close in frequency is known as
readability
stability
selectivity
sensitivity
A radiofrequency bypass capacitor
blocks radio frequencies and passes direct current
blocks direct current and passes radio frequencies
must have a high reactance in order to be effective
provides a low inpedance path for direct current
Long distance high-frequency communication at night is normally via the ionospheric
D layer
F layer
E layer
N layer
One KHz is the same as
10 Hz
100 Hz
1,000 Hz
10,000 Hz
When compared to ground wave propagation sky wave propagation usually has
Much smaller effective range
Much greater effective range
The same effective range
Differing effective range depending of the weather
To extend the range of an ammeter it is necessary to use a
resistor in series with the meter
resistor in parallel with the meter
rectifier in series with the meter
capacitor in parallel with the meter
An interfering signal from a Standard transmitter appears on 56.6MHz. This could be due to the
crystal oscillator operating on its fundamental frequency
second harmonic of a 10 metre transmission
third harmonic of a 15 metre transmission
seventh harmonic of an 80 metre transmission
The main reason for earthing mains powered equipment is to
reduce RF interference
reduce eddy currents
reduce shock hazards
reduce stray coupling
This carbon filament resistor may be described as
220K ohms 5%
22K ohms 5%
220K ohms 10%
56 ohms 5%
The reactance of an inductor
increases as the applied frequency rises
decreases as the applied frequency rises
decreases as the inductance rises
is proportional to the current flow
To convert alternating current to direct current, use is made of a
thermister
resonant circuit
diode
carbon resistor
A receiver which cannot pick up weak signals is lacking in
sensitivity
selectivity
modulation
stability
What type of modulation system changes the amplitude of an RF wave for the purpose of conveying information?
frequency modulation
phase modulation
amplitude-rectification modulation
amplitude modulation
Bleeder resistors are included in power supplies to
discharge filter capacitors after the supply voltage is switched off
prevent damage to filter during overload
reduce ripple in the output voltage
reduce the size of the filter choke
Which of the following is a type of electrolytic capacitor?
plastic
mica
tantalum
ceramic
The amount of forward bias required to enable a germanium transistor to commence conduction is approximately
0.2 volt
0.6 volt
0.9 volt
1.0 volt
Four 10 ohm resistors are connected in series. The total resistance is
2.5 ohms
4 ohms
10 ohms
40 ohms
The purpose of the capacitor in this filter circuit is to
pass the low frequency
bypass the high frequencies
attenuate the low frequencies
amplify the high frequencies
In fitting an amateur transceiver to a motor vehicle an important matter to consider is?
whether there is voltage available to power the transceiver
the placement of a laptop computer for logging purposes
potential interference to the engine management system
signal reflections from the wing mirrors
When a current of 10 millamperes flows through a resistance of 10 ohms, the voltage drop across the resistor is
10 millivolts
100 millivolts
1 volt
10 volt
The best method of eliminating TV set front end overload caused by proximity to an 80, 15 and 10 metre amateur transmitter is to
use a high pass filter on the tv receiver
use a low pass filter on the transmitter
install a wave trap in the TV set's feedline
install a power line filter
Crystal oscillators are often used for frequency control in receivers because they
have more output than other oscillators
are more stable than L-C oscillators
radiate fewer harmonics than other oscillators
generate more harmonics than other oscillators
The purpose of the AGC in a superheterodyne receiver is to
maintain a constant current drain from the power supply
maintain a constant output level with wide input variations
provide a small variation in receiver tuning
keep the local oscillator frequency constant
The active conductor in a 3-core AC power cords is coloured
brown
yellow/green
red
blue
The total resistance of four 68 ohm resistors in parallel is
272 ohms
12 ohms
17 ohms
34 ohms
The mode of operation of this amplifier is known as a
common emitter
common collector
common drain
common gate
The mixing of audio and radio frequency signals is
frequency multiplication
frequency mixing
detection
modulation
The term 'hFE' or 'beta' of a transistor is its
noise figure
current amplification factor
operating speed
breakdown voltage
The frequency of the local oscillator is
910KHz
3625KHz
4080KHz
4990KHz
The RMS value of a sine wave can be calculated by
peak x 2
peak + 2
peak x 0.707
peak x 1.414
This circuit diagram shows
resistor and capacitor in parallel
resistor and capacitor in series
resistor and inductor in series
capacitor and inductor in parallel
The basic filter characteristic drawn below, represents that of a
low pass
high pass
bandpass
bandstop
Voltage variable capacitor (varicap or varactor) diodes behave as capacitors when
biased in the forward direction
un-biased
saturated
biased in the reverse direction
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