2021 Advanced Qualification pool
547 / 549 questions need explanations
All explanations are written and maintained by ordinary users like you! Please help us finish the explanations in this pool.
The advantage of the capacitor input filter over the choke input filter is:
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better filtering action or smaller ripple voltage (46% chose this)
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improved voltage regulation (31% chose this)
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lower peak rectifier currents (8% chose this)
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a higher terminal voltage output (15% chose this)
In a grounded grid amplifier using a triode vacuum tube, the cathode is connected to a radio frequency choke. The other end of the radio frequency choke connects to the:
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B- (bias) (27% chose this)
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ground (28% chose this)
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filament voltage (12% chose this)
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B+ (high voltage) (33% chose this)
Which of these antennas does not produce circular polarization?
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Lindenblad antenna (37% chose this)
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Axial-mode helical antenna (4% chose this)
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Loaded helical-wound antenna (31% chose this)
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Crossed dipoles fed 90 degrees out of phase (28% chose this)
AGC is derived in a receiver from one of two circuits. Depending on the method used, it is called:
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IF derived or RF derived (39% chose this)
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detector derived or audio derived (5% chose this)
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IF derived or audio derived (29% chose this)
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RF derived or audio derived (27% chose this)
What is an EXCLUSIVE NOR gate?
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A circuit that produces a logic "1" at its output when only one of the inputs is logic "0" (28% chose this)
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A circuit that produces a logic "1" at its output when only one of the inputs are logic "1" (26% chose this)
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A circuit that produces a logic "0" at its output when all of the inputs are logic "1" (15% chose this)
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A circuit that produces a logic "1" at its output when all of the inputs are logic "1" (31% chose this)
Adding one bit to the word length, is equivalent to adding ____ dB to the dynamic range of the digitizer:
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1 dB (7% chose this)
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4 dB (7% chose this)
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3 dB (55% chose this)
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6 dB (31% chose this)
What part of a superheterodyne receiver determines the image rejection ratio of the receiver?
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AGC loop (2% chose this)
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IF filter (44% chose this)
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RF amplifier pre-selector (27% chose this)
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Product detector (26% chose this)
The characteristic difference between a phase modulator and a frequency modulator is:
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the centre frequency (17% chose this)
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de-emphasis (23% chose this)
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frequency inversion (23% chose this)
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pre-emphasis (37% chose this)
Antenna beamwidth is the angular distance between:
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the 3 dB power points on the first minor lobe (26% chose this)
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the points on the major lobe at the half-power points (31% chose this)
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the maximum lobe spread points on the major lobe (22% chose this)
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the 6 dB power points on the major lobe (21% chose this)
What is the frequency deviation for a 12.21-MHz reactance-modulated oscillator in a +/- 5-kHz deviation, 146.52-MHz FM-phone transmitter?
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+/- 12 kHz (10% chose this)
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+/- 5 kHz (45% chose this)
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+/- 41.67 Hz (11% chose this)
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+/- 416.7 Hz (34% chose this)
Automatic Level Control (ALC) is another name for:
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AF clipping (16% chose this)
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RF compression (31% chose this)
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AF compression (35% chose this)
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RF clipping (19% chose this)
In a grounded grid amplifier using a triode vacuum tube, the plate is connected to the pi-network through a:
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electrolytic capacitor (11% chose this)
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blocking capacitor (34% chose this)
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by-pass capacitor (31% chose this)
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tuning capacitor (24% chose this)
Where you require bandwidth at VHF and higher frequencies about equal to a television channel, a good choice of filter is the:
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Butterworth (25% chose this)
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Chebyshev (15% chose this)
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none of the other answers (29% chose this)
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resonant cavity (31% chose this)
Crystals are sometimes used in a circuit which has an output close to an integral multiple of the crystal frequency. This circuit is called:
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a crystal ladder (12% chose this)
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an overtone oscillator (31% chose this)
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a crystal multiplier (35% chose this)
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a crystal lattice (22% chose this)
Which device relies on a stable low-frequency oscillator, with harmonic output, to facilitate the frequency calibration of receiver dial settings?
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Signal generator (24% chose this)
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Harmonic calibrator (28% chose this)
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Frequency counter (17% chose this)
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Frequency-marker generator (31% chose this)
A Yagi antenna uses a gamma match. The centre of the driven element connects to:
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the adjustable gamma rod (21% chose this)
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a variable capacitor (19% chose this)
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the coaxial line braid (40% chose this)
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the coaxial line centre conductor (19% chose this)
AGC voltage is applied to the:
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RF and IF amplifiers (38% chose this)
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AF and IF amplifiers (21% chose this)
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RF and AF amplifiers (23% chose this)
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detector and AF amplifiers (18% chose this)
Which of these measurements is a good indicator of VHF receiver performance in an environment of strong out-of-band signals?
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Intermediate frequency rejection ratio (35% chose this)
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Two-tone Third-Order IMD Dynamic Range, 10 MHz spacing (43% chose this)
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Third-Order Intercept Point (9% chose this)
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Blocking Dynamic Range (13% chose this)
In any regulated power supply, the output is cleanest and the regulation is best:
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across the secondary of the pass transistor (10% chose this)
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across the load (38% chose this)
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at the output of the pass transistor (16% chose this)
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at the point where the sampling network or error amplifier is connected (36% chose this)
Which of the following is not correct? Waveguide is an efficient transmission medium because it features:
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low radiation loss (24% chose this)
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low dielectric loss (15% chose this)
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low copper loss (26% chose this)
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low hysteresis loss (35% chose this)
An advantage of keying the buffer stage in a transmitter is that:
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changes in oscillator frequency are less likely (43% chose this)
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key clicks are eliminated (38% chose this)
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the radiated bandwidth is restricted (6% chose this)
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high RF voltages are not present (13% chose this)
What term describes a method used to match a high-impedance transmission line to a lower impedance antenna by connecting the line to the driven element in two places, spaced a fraction of a wavelength on each side of the driven element centre?
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The omega match (10% chose this)
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The stub match (11% chose this)
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The T match (40% chose this)
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The gamma match (40% chose this)
What type of linear voltage regulator is used in applications requiring a constant load on the unregulated voltage source?
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A shunt current source (4% chose this)
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A series regulator (23% chose this)
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A shunt regulator (38% chose this)
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A constant current source (35% chose this)
In a simple 2 stage CW transmitter, current to the collector of the transistor in the class C amplifier stage flows through a radio frequency choke (RFC) and a tapped inductor. The RFC, on the tapped inductor side, is also connected to grounded capacitors. The purpose of the RFC and capacitors is to:
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form a low-pass filter (38% chose this)
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provide negative feedback (6% chose this)
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form a key-click filter (13% chose this)
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form a RF-tuned circuit (43% chose this)
Parasitic oscillations are usually generated due to:
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a mismatch between power amplifier and transmission line (11% chose this)
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accidental resonant frequencies in the power amplifier (35% chose this)
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harmonics from some earlier multiplier stage (28% chose this)
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excessive drive or excitation to the power amplifier (26% chose this)
The main function of the bleeder resistor in a power supply is to provide a discharge path for the capacitor in the power supply. But it may also be used for a secondary function, which is to:
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act as a secondary smoothing device in conjunction with the filter (32% chose this)
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improve voltage regulation (37% chose this)
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provide a ground return for the transformer (24% chose this)
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inhibit the flow of current through the supply (7% chose this)
In a regulated power supply, components that conduct alternating current at the input before the transformer and direct current before the output are:
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chokes (19% chose this)
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fuses (39% chose this)
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capacitors (21% chose this)
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diodes (21% chose this)
What is direct-sequence spread spectrum?
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The carrier is amplitude modulated over a range called the spread (8% chose this)
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The carrier is frequency-companded (1% chose this)
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The carrier is altered in accordance with a pseudo-random list of channels (49% chose this)
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The carrier is phase-shifted by a fast binary bit stream (42% chose this)
Which two stages in a superheterodyne receiver have input tuned circuits tuned to the same frequency?
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IF and local oscillator (22% chose this)
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RF and IF (22% chose this)
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RF and local oscillator (18% chose this)
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RF and first mixer (39% chose this)
A Yagi antenna uses a gamma match. The adjustable gamma rod connects to:
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an adjustable point on the reflector (10% chose this)
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the centre of the driven element (32% chose this)
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the variable capacitor (40% chose this)
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the coaxial line centre conductor (18% chose this)
In a grounded grid amplifier using a triode vacuum tube, the plate is connected to a radio frequency choke. The other end of the radio frequency choke connects to the:
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ground (22% chose this)
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B- (bias) (28% chose this)
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B+ (high voltage) (39% chose this)
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filament voltage (11% chose this)
Maintaining the peak RF output of a SSB transmitter at a relatively constant level requires a circuit called the:
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automatic level control (ALC) (42% chose this)
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automatic gain control (AGC) (51% chose this)
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automatic output control (AOC) (7% chose this)
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automatic volume control (AVC) (0% chose this)
In the common base amplifier, the input impedance, when compared to the output impedance is:
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only slightly lower (12% chose this)
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very high (41% chose this)
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very low (43% chose this)
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only slightly higher (4% chose this)
What term is used to describe a spread spectrum communications system in which a very fast binary bit stream is used to shift the phase of an RF carrier?
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Direct sequence (42% chose this)
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Frequency hopping (17% chose this)
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Phase companded spread spectrum (12% chose this)
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Binary phase-shift keying (29% chose this)
What kind of impedance does a quarter wavelength transmission line present to the source if the line is open at the far end?
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A very high impedance (40% chose this)
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The same as the output impedance of the source (1% chose this)
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The same as the characteristic impedance of the transmission line (10% chose this)
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A very low impedance (48% chose this)
What is meant by the term op-amp offset voltage?
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The difference between the output voltage of the op-amp and the input voltage required for the next stage (20% chose this)
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The potential between the amplifier input terminals of the op-amp in an open-loop condition (18% chose this)
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The output voltage of the op-amp minus its input voltage (20% chose this)
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The potential between the amplifier input terminals of the op-amp in a closed-loop condition (42% chose this)
What is the primary purpose of an RF amplifier in a receiver?
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To provide most of the receiver gain (49% chose this)
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To improve the receiver noise figure (43% chose this)
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To vary the receiver image rejection by using the AGC (5% chose this)
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To develop the AGC voltage (3% chose this)
What error-correction system is used in AMTOR FEC (Mode B)?
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The receiving station checks the frame check sequence (FCS) against the transmitted FCS (29% chose this)
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Each character is sent twice (43% chose this)
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Mode B AMTOR does not include an error-correction system (14% chose this)
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The receiving station automatically requests repeats when needed (13% chose this)
What is the equivalent to the RMS value of an AC voltage?
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The AC voltage found by taking the square root of the average AC value (13% chose this)
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The AC voltage causing the same heating of a given resistor as a DC voltage of the same value (43% chose this)
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The AC voltage found by taking the square root of the peak AC voltage (18% chose this)
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The DC voltage causing the same heating of a given resistor as the peak AC voltage (25% chose this)
The alpha of a bipolar transistor is specified for what configuration?
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Common collector (17% chose this)
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Common gate (13% chose this)
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Common emitter (31% chose this)
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Common base (38% chose this)
In a simple 2 stage CW transmitter circuit, the oscillator stage and the class C amplifier stage are inductively coupled by a RF transformer. Another role of the RF transformer is to:
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provide the necessary feedback for oscillation (30% chose this)
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act as part of a balanced mixer (14% chose this)
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be part of a tuned circuit (43% chose this)
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act as part of a pi filter (12% chose this)
Intermodulation interference products are not typically associated with which of the following:
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intermediate frequency stage (38% chose this)
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final amplifier stage (28% chose this)
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receiver frontend (19% chose this)
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passive intermodulation (15% chose this)
What type of error control system is used in AMTOR ARQ (Mode A)?
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The receiving station automatically requests repeats when needed (43% chose this)
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The receiving station checks the frame check sequence (FCS) against the transmitted FCS (21% chose this)
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Each character is sent twice (18% chose this)
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Mode A AMTOR does not include an error control system (17% chose this)
Parasitic oscillations in an RF power amplifier may be caused by:
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excessive harmonic production (23% chose this)
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lack of neutralization (41% chose this)
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overdriven stages (26% chose this)
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poor voltage regulation (10% chose this)
For an antenna tuner of the "L" type, which of the following statements is false?
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The circuit is known as an L-type antenna tuner (9% chose this)
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The circuit is suitable for matching to a vertical ground plane antenna (40% chose this)
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The transmitter input is suitable for 50 ohms impedance (12% chose this)
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The antenna output is high impedance (39% chose this)
What advantage does a pi-L network have over a pi-network for impedance matching between a vacuum tube linear amplifier and a multiband antenna?
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Greater transformation range (22% chose this)
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Greater harmonic suppression (46% chose this)
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Higher efficiency (15% chose this)
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Lower losses (17% chose this)
Voltmeter sensitivity is usually expressed in ohms per volt. This means that a voltmeter with a sensitivity of 20 kilohms per volt would be a:
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50 microampere meter (46% chose this)
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1 milliampere meter (8% chose this)
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50 milliampere meter (33% chose this)
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100 milliampere meter (13% chose this)
In a full-wave centre-tap power supply, regardless of load conditions, the peak inverse voltage (PIV) will be _____ times the RMS voltage:
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1.4 (26% chose this)
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2.8 (41% chose this)
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0.636 (3% chose this)
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0.707 (30% chose this)
The peak power output of a single-sideband transmitter, when being tested by a two-tone generator is:
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one-half of the RF peak output power of any of the tones (21% chose this)
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one-quarter of the RF peak output power of any of the tones (4% chose this)
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twice the RF power output of any of the tones (43% chose this)
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equal to the RF peak output power of any of the tones (32% chose this)
In a frequency multiplier circuit, an inductance (L1) and a variable capacitor (C2) are connected in series between VCC+ and ground. The collector of a transistor is connected to a tap on L1. A fixed capacitor (C3) is connected between the VCC+ side of L1 and ground. C3 is a:
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DC blocking capacitor (30% chose this)
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tuning capacitor (14% chose this)
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coupling capacitor (13% chose this)
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RF by-pass capacitor (43% chose this)
A dip meter:
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may be used only with series tuned circuits (14% chose this)
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accurately measures frequencies (14% chose this)
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should be loosely coupled to the circuit under test (45% chose this)
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should be tightly coupled to the circuit under test (26% chose this)
There are two types of filters in general use in a power supply. They are called:
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choke input and capacitor output (38% chose this)
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choke output and capacitor input (10% chose this)
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choke input and capacitor input (44% chose this)
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choke output and capacitor output (9% chose this)
The FET amplifier common drain circuit is similar to which of the following bipolar transistor amplifier circuits?
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Common mode (1% chose this)
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Common collector (45% chose this)
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Common emitter (27% chose this)
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Common base (27% chose this)
Which of the following circuits gives the best regulation, under similar load conditions?
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A half-wave bridge rectifier with a capacitor input filter (10% chose this)
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A half-wave rectifier with a choke input filter (3% chose this)
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A full-wave rectifier with a capacitor input filter (43% chose this)
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A full-wave rectifier with a choke input filter (44% chose this)
An AC voltmeter is calibrated to read the:
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peak value (11% chose this)
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effective value (46% chose this)
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peak-to-peak value (17% chose this)
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average value (26% chose this)
Any FM wave with single-tone modulation has:
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an infinite number of sideband frequencies (47% chose this)
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two sideband frequencies (31% chose this)
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four sideband frequencies (4% chose this)
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one sideband frequency (18% chose this)
The FET amplifier source follower circuit is another name for:
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common mode circuit (10% chose this)
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common gate circuit (19% chose this)
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common drain circuit (39% chose this)
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common source circuit (32% chose this)
What kind of impedance does a half wavelength transmission line present to the source when the line is shorted at the far end?
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The same as the output impedance of the source (5% chose this)
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A very low impedance (47% chose this)
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A very high impedance (35% chose this)
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The same as the characteristic impedance of the transmission line (13% chose this)
What type of circuit varies the tuning of an amplifier tank circuit to produce FM signals?
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A phase modulator (51% chose this)
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A balanced modulator (37% chose this)
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A double balanced mixer (3% chose this)
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An audio modulator (9% chose this)
The dynamic regulation of a power supply is improved by increasing the value of:
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the input capacitor (30% chose this)
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the bleeder resistor (14% chose this)
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the output capacitor (47% chose this)
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the choke (8% chose this)
How is antenna percent efficiency calculated?
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(radiation resistance / transmission resistance) x 100 (6% chose this)
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(total resistance / radiation resistance) x 100 (13% chose this)
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(effective radiated power / transmitter output) x 100 (30% chose this)
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(radiation resistance / total resistance) x 100 (51% chose this)
What is the beta of a bipolar transistor?
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The change of collector current with respect to emitter current (22% chose this)
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The change of base current with respect to gate current (14% chose this)
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The change of collector current with respect to base current (46% chose this)
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The change of base current with respect to emitter current (19% chose this)
How is remote sensing accomplished in a linear voltage regulator?
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A load connection is made outside the feedback loop (16% chose this)
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By wireless inductive loops (5% chose this)
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A feedback connection to an error amplifier is made directly to the load (49% chose this)
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An error amplifier compares the input voltage to the reference voltage (29% chose this)
In a grounded grid amplifier using a triode vacuum tube, the secondary winding of a transformer is connected directly to the vacuum tube. This transformer provides:
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Screen voltage (12% chose this)
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filament voltage (47% chose this)
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B- (bias) (24% chose this)
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B+ (high voltage) (17% chose this)
What is the output PEP from a transmitter if an oscilloscope measures 200 volts peak-to-peak across a 50-ohm dummy load connected to the transmitter output?
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400 watts (23% chose this)
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1000 watts (11% chose this)
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200 watts (16% chose this)
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100 watts (49% chose this)
Some types of deviation meters work on the principle of:
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a carrier null and multiplying the modulation frequency by the modulation index (54% chose this)
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detecting the frequencies in the sidebands (12% chose this)
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the amplitude of power in the sidebands (16% chose this)
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a carrier peak and dividing by the modulation index (19% chose this)
Intermodulation interference is produced by:
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the mixing of more than one signal in the first or second intermediate frequency amplifiers of a receiver (28% chose this)
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the mixing of two or more signals in the front-end of a superheterodyne receiver (47% chose this)
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the interaction of products from high-powered transmitters in the area (23% chose this)
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the high-voltage stages in the final amplifier of an amplitude or frequency-modulated transmitter (3% chose this)
When using Lissajous figures to determine phase differences, an indication of zero or 180 degrees is represented on the screen of an oscilloscope by:
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a diagonal straight line (51% chose this)
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a horizontal straight line (18% chose this)
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an ellipse (17% chose this)
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a circle (14% chose this)
What is an enhancement-mode FET?
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An FET without a channel; no current occurs with zero gate voltage (44% chose this)
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An FET with a channel that blocks voltage through the gate (9% chose this)
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An FET with a channel that allows current when the gate voltage is zero (36% chose this)
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An FET without a channel to hinder current through the gate (11% chose this)
A 100-kHz signal is applied to the horizontal channel of an oscilloscope. A signal of unknown frequency is applied to the vertical channel. The resultant wave form has 5 loops displayed vertically and 2 loops horizontally. The unknown frequency is:
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20 kHz (29% chose this)
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50 kHz (17% chose this)
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30 kHz (6% chose this)
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40 kHz (47% chose this)
What is the output PEP from a transmitter, if an oscilloscope measures 400 volts peak-to-peak across a 50 ohm dummy load connected to the transmitter output?
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600 watts (8% chose this)
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1000 watts (14% chose this)
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400 watts (51% chose this)
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200 watts (26% chose this)
A moving-coil milliammeter having a full-scale deflection of 1 mA and an internal resistance of 0.5 ohms is to be converted to a voltmeter of 20 volts full-scale deflection. It would be necessary to insert a:
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shunt resistance of 19 999.5 ohms (14% chose this)
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shunt resistance of 19.5 ohms (25% chose this)
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series resistance of 19 999.5 ohms (49% chose this)
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series resistance of 1 999.5 ohms (12% chose this)
A Yagi antenna uses a gamma match. The variable capacitor connects to the:
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adjustable gamma rod (52% chose this)
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an adjustable point on the director (14% chose this)
-
center of the driven element (25% chose this)
-
coaxial line braid (8% chose this)
What audio shaping network is added at an FM transmitter to attenuate the lower audio frequencies?
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A pre-emphasis network (47% chose this)
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An audio prescaler (14% chose this)
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A heterodyne suppressor (12% chose this)
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A de-emphasis network (27% chose this)
The FET amplifier common source circuit is similar to which of the following bipolar transistor amplifier circuits?
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Common emitter (47% chose this)
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Common collector (29% chose this)
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Common base (21% chose this)
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Common mode (3% chose this)
How is positive feedback coupled to the input in a Colpitts oscillator?
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Through a link coupling (14% chose this)
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Through a capacitive divider (46% chose this)
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Through a tapped coil (29% chose this)
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Through a neutralizing capacitor (11% chose this)
In a superheterodyne receiver, a stage before the IF amplifier has a variable capacitor in parallel with a trimmer capacitor and an inductance. The variable capacitor is for:
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tuning of the beat-frequency oscillator (BFO) (30% chose this)
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tuning both the antenna and the LO (14% chose this)
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tuning of the local oscillator (LO) (50% chose this)
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tuning both the antenna and the BFO (7% chose this)
If a receiver tuned to 146.70 MHz receives an intermodulation product signal whenever a nearby transmitter transmits on 146.52, what are the two most likely frequencies for the other interfering signal?
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146.88 MHz and 146.34 MHz (40% chose this)
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146.01 MHz and 147.30 MHz (8% chose this)
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73.35 MHz and 239.40 MHz (11% chose this)
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146.34 MHz and 146.61 MHz (42% chose this)
Which description is not correct? You are planning to build a speech processor for your transceiver. Compared to AF clipping, RF clipping:
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is more expensive to implement (9% chose this)
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is more difficult to implement (30% chose this)
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is easier to implement (46% chose this)
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has less distortion (15% chose this)
Which two instruments are needed to measure FM receiver sensitivity for a 12 dB SINAD ratio (signal + noise + distortion over noise + distortion)?
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Oscilloscope and spectrum analyzer (25% chose this)
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Receiver noise bridge and total harmonic distortion analyser (4% chose this)
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Calibrated RF signal generator with FM tone modulation and total harmonic distortion (THD) analyzer (53% chose this)
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RF signal generator with FM tone modulation and a deviation meter (18% chose this)
In an FM transmitter system, the amount of deviation from the centre frequency is determined solely by the:
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amplitude and the frequency of the modulating frequency (16% chose this)
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modulating frequency and the amplitude of the centre frequency (17% chose this)
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amplitude of the modulating frequency (49% chose this)
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frequency of the modulating frequency (18% chose this)
Parasitic oscillations would tend to occur mostly in:
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RF power output stages (52% chose this)
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high gain audio output stages (19% chose this)
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high voltage rectifiers (10% chose this)
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mixer stages (19% chose this)
When it is gated "on", the silicon controlled rectifier (SCR) exhibits electrical characteristics similar to a:
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reverse-biased silicon rectifier (8% chose this)
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forward-biased PIN diode (33% chose this)
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reverse-biased hot-carrier (Schottky) diode (15% chose this)
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forward-biased silicon rectifier (44% chose this)
The beta of a bipolar transistor is specified for what configurations?
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Common emitter or common collector (44% chose this)
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Common emitter or common gate (9% chose this)
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Common base or common collector (22% chose this)
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Common base or common emitter (24% chose this)
In a grounded grid amplifier using a triode vacuum tube, what would be the approximate B+ voltage required for an output of 400 watts at 400 mA with approximately 50 percent efficiency?
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500 volts (21% chose this)
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3000 volts (7% chose this)
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1000 volts (18% chose this)
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2000 volts (54% chose this)
Why must a very stable reference oscillator be used as part of a phase-locked loop (PLL) frequency synthesizer?
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Any amplitude variations in the reference oscillator signal will prevent the loop from changing frequency (8% chose this)
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Any amplitude variations in the reference oscillator signal will prevent the loop from locking to the desired signal (13% chose this)
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Any phase variations in the reference oscillator signal will produce phase noise in the synthesizer output (48% chose this)
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Any phase variations in the reference oscillator signal will produce harmonic distortion in the modulating signal (32% chose this)
The purpose of using a centre-tap return connection on the secondary of transmitting tube's filament transformer is to:
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obtain optimum power output (7% chose this)
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prevent modulation of the emitted wave by the alternating current filament supply (53% chose this)
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reduce the possibility of harmonic emissions (25% chose this)
-
keep the output voltage constant with a varying load (15% chose this)
For rectangular waveguide to transfer energy, the cross-section should be at least:
-
three-eighths wavelength (3% chose this)
-
one-eighth wavelength (12% chose this)
-
one-quarter wavelength (32% chose this)
-
one-half wavelength (53% chose this)
If a frequency counter, with a time base accuracy of 10 PPM (parts per million) reads 146 520 000 Hz, what is the most the actual frequency being measured could differ from that reading?
-
1465.2 kHz (12% chose this)
-
1465.2 Hz (48% chose this)
-
146.52 Hz (25% chose this)
-
146.52 kHz (15% chose this)
One antenna which will respond simultaneously to vertically- and horizontally-polarized signals is the:
-
helical-beam antenna (55% chose this)
-
folded dipole antenna (7% chose this)
-
ground-plane antenna (4% chose this)
-
quad antenna (34% chose this)
In a frequency multiplier circuit, the input signal is coupled to the base of a transistor through a capacitor. A radio frequency choke is connected between the base of the transistor and ground. The capacitor is:
-
part of the input tuned circuit (27% chose this)
-
a by-pass for the circuit (17% chose this)
-
part of the output tank circuit (4% chose this)
-
a DC blocking capacitor (52% chose this)
How much is the carrier suppressed below peak output power in a single-sideband phone transmission?
-
At least 60 dB (19% chose this)
-
At least 40 dB (57% chose this)
-
No more than 20 dB (14% chose this)
-
No more than 30 dB (10% chose this)
In amateur work, what is the surface error upper limit you should try not to exceed on a parabolic reflector?
-
0.25 lambda (19% chose this)
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5 mm (0.2 in) regardless of frequency (7% chose this)
-
1% of the diameter (25% chose this)
-
0.1 lambda (49% chose this)
What audio shaping network is added at an FM receiver to restore proportionally attenuated lower audio frequencies?
-
A heterodyne suppressor (6% chose this)
-
A de-emphasis network (51% chose this)
-
A pre-emphasis network (27% chose this)
-
An audio prescaler (16% chose this)
The ripple frequency produced by a full-wave power supply connected to a normal household circuit is:
-
30 Hz (0% chose this)
-
120 Hz (54% chose this)
-
60 Hz (45% chose this)
-
90 Hz (1% chose this)
What is included in the total resistance of an antenna system?
-
Radiation resistance plus transmission resistance (15% chose this)
-
Transmission line resistance plus radiation resistance (34% chose this)
-
Radiation resistance plus space impedance (2% chose this)
-
Radiation resistance plus ohmic resistance (49% chose this)
The dip meter is most directly applicable to:
-
digital logic circuits (5% chose this)
-
series tuned circuits (28% chose this)
-
parallel tuned circuits (49% chose this)
-
operational amplifier circuits (18% chose this)
The regulation of long-term changes in the load resistance of a power supply is called:
-
static regulation (51% chose this)
-
active regulation (10% chose this)
-
analog regulation (3% chose this)
-
dynamic regulation (37% chose this)
What is the alpha of a bipolar transistor?
-
The change of base current with respect to collector current (13% chose this)
-
The change of collector current with respect to gate current (18% chose this)
-
The change of collector current with respect to emitter current (44% chose this)
-
The change of collector current with respect to base current (24% chose this)
Excessive rectifier peak current and abnormally high peak inverse voltages can be caused in a power supply by the filter forming a:
-
tuned inductance in the filter choke (9% chose this)
-
series resonant circuit with the first choke and first capacitor (54% chose this)
-
short circuit across the bleeder (15% chose this)
-
parallel resonant circuit with the first choke and second capacitor (22% chose this)
For the same transformer secondary voltage, which rectifier has the highest average output voltage?
-
Half-wave (0% chose this)
-
Quarter-wave (3% chose this)
-
Full-wave centre-tap (45% chose this)
-
Bridge (53% chose this)
Which stage of a superheterodyne receiver lies between a tuneable stage and a fixed tuned stage?
-
Local oscillator (16% chose this)
-
Mixer (56% chose this)
-
Radio frequency amplifier (7% chose this)
-
Intermediate frequency amplifier (21% chose this)
What is the significant bandwidth of an FM-phone transmission having a +/- 5-kHz deviation and a 3-kHz modulating frequency?
-
8 kHz (23% chose this)
-
5 kHz (12% chose this)
-
3 kHz (11% chose this)
-
16 kHz (55% chose this)
What causes intermodulation in an electronic circuit?
-
Nonlinear circuits or devices (52% chose this)
-
Too little gain (1% chose this)
-
Positive feedback (16% chose this)
-
Lack of neutralization (30% chose this)
Beta of a bipolar transistor is equal to:
-
alpha x (1 - alpha) (15% chose this)
-
alpha x (1 + alpha) (11% chose this)
-
alpha / (1 - alpha) (52% chose this)
-
alpha / (1 + alpha) (22% chose this)
Which of the following statements about waveguide IS NOT correct?
-
In the transverse electric mode, a component of the magnetic field is in the direction of propagation (5% chose this)
-
In the transverse magnetic mode, a component of the electric field is in the direction of propagation (1% chose this)
-
Waveguide has low loss at high frequencies, but high loss below cutoff frequency (37% chose this)
-
Waveguide has high loss at high frequencies, but low loss below cutoff frequency (56% chose this)
What determines the output impedance of a FET common-source amplifier?
-
The output impedance is essentially determined by the drain resistor (49% chose this)
-
The output impedance is essentially determined by the drain supply voltage (8% chose this)
-
The output impedance is essentially determined by the gate supply voltage (27% chose this)
-
The output impedance is essentially determined by the input impedance of the FET (16% chose this)
Which of the following is not a method used for peak limiting, in a signal processor?
-
AF clipping (11% chose this)
-
Frequency clipping (58% chose this)
-
RF clipping (18% chose this)
-
Compression (13% chose this)
Out of the following oscillators, one is NOT, by itself, considered a high-stability reference:
-
oven-controlled crystal oscillator (OCXO) (14% chose this)
-
GPS disciplined oscillator (GPSDO) (20% chose this)
-
voltage-controlled crystal oscillator (VCXO) (57% chose this)
-
temperature compensated crystal oscillator (TCXO) (9% chose this)
For long distance propagation, the vertical radiation angle of the energy from the antenna should be:
-
more than 30 degrees but less than 45 degrees (25% chose this)
-
less than 30 degrees (55% chose this)
-
more than 45 degrees but less than 90 degrees (17% chose this)
-
90 degrees (3% chose this)
A voltmeter having a range of 150 volts and an internal resistance of 150 000 ohms is to be extended to read 750 volts. The required multiplier resistor would have a value of:
-
1 500 ohms (8% chose this)
-
750 000 ohms (38% chose this)
-
1 200 000 ohms (5% chose this)
-
600 000 ohms (49% chose this)
In the common emitter amplifier, when the input and output signals are compared:
-
the output signal leads the input signal by 90 degrees (4% chose this)
-
the output signal lags the input signal by 90 degrees (9% chose this)
-
the signals are in phase (32% chose this)
-
the signals are 180 degrees out of phase (55% chose this)
In the design of a power supply, the designer must be careful of resonance effects because the ripple voltage could build up to a high value. The components that must be carefully selected are:
-
first capacitor and second capacitor (11% chose this)
-
first choke and second capacitor (5% chose this)
-
first choke and first capacitor (56% chose this)
-
the bleeder resistor and the first choke (28% chose this)
What is the alpha of a bipolar transistor in common base configuration?
-
Forward current gain (51% chose this)
-
Forward voltage gain (42% chose this)
-
Reverse current gain (4% chose this)
-
Reverse voltage gain (4% chose this)
As a power amplifier is tuned, what reading on its grid current meter indicates the best neutralization?
-
Minimum grid current (24% chose this)
-
Maximum grid current (10% chose this)
-
A maximum change in grid current as the output circuit is changed (12% chose this)
-
A minimum change in grid current as the output circuit is changed (54% chose this)
How can the frequency response of an oscilloscope be improved?
-
By using triggered sweep and a crystal oscillator for the timebase (10% chose this)
-
By increasing the horizontal sweep rate and the vertical amplifier frequency response (53% chose this)
-
By using a crystal oscillator as the time base and increasing the vertical sweep rate (19% chose this)
-
By increasing the vertical sweep rate and the horizontal amplifier frequency response (18% chose this)
In a frequency multiplier circuit, an inductance (L1) and a variable capacitor (C2) are connected in series between VCC+ and ground. The collector of a transistor is connected to a tap on L1. The purpose of the variable capacitor is to:
-
tune L1 to the desired harmonic (53% chose this)
-
by-pass RF (11% chose this)
-
tune L1 to the frequency applied to the base (22% chose this)
-
provide positive feedback (14% chose this)
Normally, front-end selectivity is provided by the resonant networks both before and after the RF stage in a superheterodyne receiver. This whole section of the receiver is often referred to as the:
-
pass-selector (12% chose this)
-
preselector (61% chose this)
-
preamble (1% chose this)
-
preamplifier (26% chose this)
What factors limit the accuracy, frequency response and stability of a frequency counter?
-
Time base accuracy, speed of the logic, and time base stability (60% chose this)
-
Time base accuracy, temperature coefficient of the logic and time base stability (27% chose this)
-
Number of digits in the readout, speed of the logic, and time base stability (6% chose this)
-
Number of digits in the readout, external frequency reference and temperature coefficient of the logic (7% chose this)
In an oscillator circuit where positive feedback is obtained through a single capacitor in series with the crystal, the type of oscillator is:
-
Colpitts (30% chose this)
-
Hartley (12% chose this)
-
Miller (5% chose this)
-
Pierce (53% chose this)
What is a common use for the hot-carrier (Schottky) diode?
-
As balanced mixers in FM generation (12% chose this)
-
As a variable capacitance in an automatic frequency control (AFC) circuit (14% chose this)
-
As a constant voltage reference in a power supply (27% chose this)
-
As VHF and UHF mixers and detectors (47% chose this)
What stage in a transmitter would change a 5.3-MHz input signal to 14.3 MHz?
-
A frequency multiplier (36% chose this)
-
A beat frequency oscillator (4% chose this)
-
A mixer (57% chose this)
-
A linear translator (4% chose this)
Which type of network provides the greatest harmonic suppression?
-
Inverse pi-network (9% chose this)
-
Pi-network (34% chose this)
-
L-network (3% chose this)
-
Pi-L network (54% chose this)
A meter has a full-scale deflection of 40 microamperes and an internal resistance of 96 ohms. You want it to read 0 to 1 mA. The value of the shunt to be used is:
-
40 ohms (15% chose this)
-
4 ohms (60% chose this)
-
24 ohms (15% chose this)
-
16 ohms (10% chose this)
What is the Q of a parallel RLC circuit, if it is resonant at 4.468 MHz, L is 47 microhenrys and R is 180 ohms?
-
0.136 (49% chose this)
-
7.35 (24% chose this)
-
0.00735 (3% chose this)
-
13.3 (24% chose this)
What type of linear regulator is used in applications requiring efficient utilization of the primary power source?
-
A constant current source (16% chose this)
-
A shunt current source (5% chose this)
-
A series regulator (57% chose this)
-
A shunt regulator (21% chose this)
In a dual-conversion superheterodyne receiver what are the respective aims of the first and second conversion:
-
selectivity and dynamic range (19% chose this)
-
image rejection and noise figure (6% chose this)
-
image rejection and selectivity (53% chose this)
-
selectivity and image rejection (22% chose this)
How many information bits are included in the Baudot code?
-
5 (56% chose this)
-
7 (8% chose this)
-
8 (27% chose this)
-
6 (9% chose this)
What kind of impedance does a half wavelength transmission line present to the source when the line is open at the far end?
-
A very high impedance (54% chose this)
-
The same as the characteristic impedance of the transmission line (14% chose this)
-
The same as the output impedance of the source (4% chose this)
-
A very low impedance (28% chose this)
In an RF oscillator circuit designed for high stability, the positive feedback is drawn from two capacitors connected in series. These two capacitors would most likely be:
-
ceramic (23% chose this)
-
electrolytics (16% chose this)
-
Mylar (7% chose this)
-
silver mica (53% chose this)
What is the Q of a parallel RLC circuit, if it is resonant at 7.125 MHz, L is 12.6 microhenrys and R is 22 kilohms?
-
22.1 (19% chose this)
-
0.0256 (11% chose this)
-
25.6 (19% chose this)
-
39 (52% chose this)
In most modern FM transmitters, to produce a better sound, a compressor and a clipper are placed:
-
between the audio amplifier and the modulator (54% chose this)
-
between the multiplier and the PA (4% chose this)
-
between the modulator and the oscillator (7% chose this)
-
in the microphone circuit, before the audio amplifier (35% chose this)
For what portion of a cycle does a Class B amplifier operate?
-
180 degrees (50% chose this)
-
Less than 180 degrees (6% chose this)
-
More than 180 degrees but less than 360 degrees (39% chose this)
-
The entire cycle (6% chose this)
The range of a DC ammeter can easily be extended by:
-
connecting an external resistance in series with the internal resistance (35% chose this)
-
changing the internal inductance of the meter (5% chose this)
-
changing the internal capacitance of the meter to resonance (5% chose this)
-
connecting an external resistance in parallel with the internal resistance (55% chose this)
What measurement can be made of a single-sideband phone transmitter's amplifier by performing a two-tone test using an oscilloscope?
-
Its linearity (57% chose this)
-
Its frequency deviation (23% chose this)
-
Its percent of carrier phase shift (8% chose this)
-
Its percent of frequency modulation (12% chose this)
Why do many MOSFET devices have built-in gate protective Zener diodes?
-
The gate-protective Zener diode provides a voltage reference to provide the correct amount of reverse-bias gate voltage (10% chose this)
-
The gate-protective Zener diode prevents the gate insulation from being punctured by small static charges or excessive voltages (51% chose this)
-
The gate-protective Zener diode keeps the gate voltage within specifications to prevent the device from overheating (19% chose this)
-
The gate-protective Zener diode protects the substrate from excessive voltages (20% chose this)
APRS (Automatic Packet Reporting System) does NOT support which one of these functions?
-
Automatic link establishment (60% chose this)
-
Two-way messaging (18% chose this)
-
Telemetry (4% chose this)
-
Amateur-specific local information broadcast (18% chose this)
What is the input impedance of a theoretically ideal op-amp?
-
Very high (60% chose this)
-
Very low (32% chose this)
-
Exactly 100 ohms (7% chose this)
-
Exactly 1000 ohms (1% chose this)
For VHF and UHF signals over a fixed path, what extra loss can be expected when linearly-polarized antennas are crossed-polarized (90 degrees)?
-
6 dB (18% chose this)
-
10 dB (7% chose this)
-
20 dB or more (59% chose this)
-
3 dB (16% chose this)
A section of waveguide:
-
operates like a low-pass filter (18% chose this)
-
operates like a band-stop filter (13% chose this)
-
is lightweight and easy to install (9% chose this)
-
operates like a high-pass filter (59% chose this)
A circuit depending on positive feedback for its operation would be a:
-
detector (18% chose this)
-
audio amplifier (21% chose this)
-
variable-frequency oscillator (52% chose this)
-
mixer (9% chose this)
What are the majority charge carriers in P-type semiconductor material?
-
Free electrons (27% chose this)
-
Free protons (14% chose this)
-
Free neutrons (1% chose this)
-
Holes (58% chose this)
In a frequency multiplier circuit, an inductance (L1) and a variable capacitor (C2) are connected in series between VCC+ and ground. The collector of a transistor is connected to a tap on L1. A fixed capacitor (C3) is connected between the VCC+ side of L1 and ground. The purpose of C3 is to:
-
resonate with L1 (11% chose this)
-
by-pass any audio components (8% chose this)
-
provide an RF ground at the VCC connection point of L1 (63% chose this)
-
form a pi filter with L1 and C2 (17% chose this)
A dip meter may not be used directly to:
-
align transmitter-tuned circuits (8% chose this)
-
determine the frequency of oscillations (23% chose this)
-
align receiver-tuned circuits (14% chose this)
-
measure the value of capacitance or inductance (56% chose this)
For a given transformer the maximum output voltage available from a full-wave bridge rectifier circuit will be:
-
double that of the full-wave centre-tap rectifier (59% chose this)
-
half that of the full-wave centre-tap rectifier (7% chose this)
-
the same as the full-wave centre-tap rectifier (20% chose this)
-
the same as the half-wave rectifier (14% chose this)
What type of signal does a balanced modulator produce?
-
Full carrier (13% chose this)
-
Single sideband, suppressed carrier (23% chose this)
-
Double sideband, suppressed carrier (56% chose this)
-
FM with balanced deviation (9% chose this)
In a communications receiver, a crystal filter would be located in the:
-
IF circuits (56% chose this)
-
local oscillator (27% chose this)
-
audio output stage (2% chose this)
-
detector (15% chose this)
How can the range of an ammeter be increased?
-
By adding resistance in series with the meter (25% chose this)
-
By adding resistance in parallel with the meter (59% chose this)
-
By adding resistance in series with the circuit under test (8% chose this)
-
By adding resistance in parallel with the circuit under test (8% chose this)
The output capacitor, in a power supply filter used to provide power for an SSB or CW transmitter, will give better dynamic regulation if:
-
the negative terminal of the electrolytic capacitor is connected to the positive and the positive terminal to ground (19% chose this)
-
a battery is placed in series with the output capacitor (4% chose this)
-
it is placed in series with other capacitors (15% chose this)
-
the output capacitance is increased (62% chose this)
In the common base amplifier, when the input and output signals are compared:
-
the signals are 180 degrees out of phase (31% chose this)
-
the signals are in phase (56% chose this)
-
the output signal lags the input signal by 90 degrees (9% chose this)
-
the output signals leads the input signal by 90 degrees (4% chose this)
Which principle is not associated with analog signal processing?
-
Clipping (8% chose this)
-
Frequency division (58% chose this)
-
Compression (22% chose this)
-
Bandwidth limiting (12% chose this)
What does a neutralizing circuit do in an RF amplifier?
-
It eliminates AC hum from the power supply (26% chose this)
-
It reduces incidental grid modulation (14% chose this)
-
It controls differential gain (1% chose this)
-
It cancels the effects of positive feedback (58% chose this)
When testing the amplitude linearity of a single-sideband transmitter what audio tones are fed into the microphone input and on what kind of kind of instrument is the output observed?
-
Two harmonically related tones are fed in, and the output is observed on an oscilloscope (18% chose this)
-
Two harmonically related tones are fed in, and the output is observed on a distortion analyzer (1% chose this)
-
Two non-harmonically related tones are fed in, and the output is observed on a distortion analyzer (20% chose this)
-
Two non-harmonically related tones are fed in, and the output is observed on an oscilloscope (61% chose this)
What is the output PEP from a transmitter if an oscilloscope measures 500 volts peak-to-peak across a 50-ohm dummy load connected to the transmitter output?
-
2500 watts (13% chose this)
-
500 watts (19% chose this)
-
625 watts (56% chose this)
-
1250 watts (13% chose this)
In the common collector amplifier, when the input and output signals are compared:
-
the signals are in phase (56% chose this)
-
the output signal leads the input signal by 90 degrees (2% chose this)
-
the output signal lags the input signal by 90 degrees (11% chose this)
-
the signals are 180 degrees out of phase (31% chose this)
When using some deviation meters, it is important to know:
-
pass-band of the IF filter (9% chose this)
-
modulating frequency and the modulation index (59% chose this)
-
modulation index (13% chose this)
-
modulating frequency (19% chose this)
What term describes an unbalanced feed system in which the driven element of an antenna is fed both at the centre and a fraction of a wavelength to one side of centre?
-
The stub match (11% chose this)
-
The T match (23% chose this)
-
The gamma match (65% chose this)
-
The omega match (1% chose this)
What kind of input signal is used to test the amplitude linearity of a single-sideband phone transmitter while viewing the output on an oscilloscope?
-
An audio-frequency square wave (7% chose this)
-
Normal speech (7% chose this)
-
Two audio-frequency sine waves (64% chose this)
-
An audio-frequency sine wave (22% chose this)
A frequency multiplier circuit must be operated in:
-
class C (59% chose this)
-
class AB (9% chose this)
-
class B (5% chose this)
-
class A (27% chose this)
Alpha of a bipolar transistor is equal to:
-
beta / (1 - beta) (32% chose this)
-
beta / (1 + beta) (56% chose this)
-
beta x (1 + beta) (9% chose this)
-
beta x (1 - beta) (4% chose this)
How is receiver sensitivity often expressed for UHF FM receivers?
-
Noise Figure in decibels (28% chose this)
-
Overall gain in decibels (8% chose this)
-
RF level for 12 dB SINAD (62% chose this)
-
RF level for a given Bit Error Rate (BER) (1% chose this)
The current gain of a bipolar transistor in common emitter or common collector compared to common base configuration is:
-
usually about half (8% chose this)
-
high to very high (53% chose this)
-
very low (21% chose this)
-
usually about double (17% chose this)
What determines the input impedance of a FET common-source amplifier?
-
The input impedance is essentially determined by the resistance between the drain and substrate (6% chose this)
-
The input impedance is essentially determined by the gate biasing network (57% chose this)
-
The input impedance is essentially determined by the resistance between the source and substrate (8% chose this)
-
The input impedance is essentially determined by the resistance between the source and the drain (29% chose this)
What is a depletion-mode FET?
-
An FET that has a channel that blocks current when the gate voltage is zero (12% chose this)
-
An FET that has a channel with no gate voltage applied; a current flows with zero gate voltage (55% chose this)
-
An FET without a channel; no current flows with zero gate voltage (29% chose this)
-
An FET without a channel to hinder current through the gate (5% chose this)
Three important parameters to be verified in an FM transmitter are:
-
distortion, bandwidth and sideband power (8% chose this)
-
modulation, pre-emphasis and carrier suppression (13% chose this)
-
frequency stability, de-emphasis and linearity (18% chose this)
-
power, frequency deviation and frequency stability (61% chose this)
Which antenna system and operating frequency are most suitable for Near Vertical Incidence (NVIS) communications?
-
A horizontal antenna at a height of half a wavelength and an operating frequency at the optimum working frequency (18% chose this)
-
A vertical antenna and a frequency below the maximum usable frequency (13% chose this)
-
A vertical antenna and a frequency above the lowest usable frequency (6% chose this)
-
A horizontal antenna less than 1/4 wavelength above ground and a frequency below the current critical frequency (64% chose this)
In a grounded grid amplifier using a triode vacuum tube, the input signal is applied to:
-
the cathode (57% chose this)
-
the plate (20% chose this)
-
the control grid (14% chose this)
-
the filament leads (9% chose this)
What limits the maximum forward current in a junction diode?
-
Back EMF (5% chose this)
-
Peak inverse voltage (25% chose this)
-
Junction temperature (49% chose this)
-
Forward voltage (20% chose this)
Which of the following is a purpose of the first IF amplifier stage in a receiver?
-
To improve selectivity and gain (58% chose this)
-
To tune out cross-modulation distortion (15% chose this)
-
To increase dynamic response (9% chose this)
-
To improve noise figure performance (18% chose this)
An oscilloscope probe must be compensated:
-
every time the probe is used with a different oscilloscope (66% chose this)
-
when measuring a sine wave (4% chose this)
-
through the addition of a high-value series resistor (14% chose this)
-
when measuring a signal whose frequency varies (16% chose this)
The noise generated in a receiver of good design originates in the:
-
detector and AF amplifier (12% chose this)
-
BFO and detector (5% chose this)
-
IF amplifier and detector (19% chose this)
-
RF amplifier and mixer (63% chose this)
In a superheterodyne receiver without an RF amplifier, the input to the mixer stage has a variable capacitor in parallel with an inductance. The variable capacitor is for:
-
tuning the beat-frequency oscillator (23% chose this)
-
tuning both the antenna and the local oscillator (11% chose this)
-
tuning the receiver preselector to the reception frequency (58% chose this)
-
tuning both the antenna and the beat-frequency oscillator (7% chose this)
Which of the following devices has anode, cathode, and gate?
-
The silicon controlled rectifier (SCR) (53% chose this)
-
The bipolar transistor (6% chose this)
-
The field effect transistor (25% chose this)
-
The triode vacuum tube (16% chose this)
Direct sequence is used with which type of transmission?
-
AMTOR (3% chose this)
-
Packet (15% chose this)
-
RTTY (18% chose this)
-
Spread spectrum (64% chose this)
What type of voltage regulator contains a voltage reference, error amplifier, sensing resistors and transistors, and a pass element in one package?
-
A three-terminal regulator (59% chose this)
-
An op-amp regulator (16% chose this)
-
A switching regulator (19% chose this)
-
A Zener regulator (6% chose this)
Which of the following is NOT a direct cause of instability in a receiver?
-
Dial display accuracy (64% chose this)
-
Mechanical rigidity (29% chose this)
-
Feedback components (5% chose this)
-
Temperature variations (1% chose this)
What is the peak-to-peak voltage of a sine wave that has an RMS voltage of 120 volts?
-
84.8 volts (9% chose this)
-
169.7 volts (23% chose this)
-
204.8 volts (8% chose this)
-
339.5 volts (60% chose this)
Which stage of a receiver has its input and output circuits tuned to the received frequency?
-
The detector (18% chose this)
-
The RF amplifier (56% chose this)
-
The local oscillator (18% chose this)
-
The audio frequency amplifier (8% chose this)
What would be the characteristics of the ideal op-amp?
-
Zero input impedance, zero output impedance, infinite gain, and flat frequency response (25% chose this)
-
Infinite input impedance, infinite output impedance, infinite gain and flat frequency response (11% chose this)
-
Zero input impedance, infinite output impedance, infinite gain, and flat frequency response (8% chose this)
-
Infinite input impedance, zero output impedance, infinite gain, and flat frequency response (56% chose this)
In a regulated power supply, the output of the electrolytic filter capacitor is connected to the:
-
solid-state by-pass circuit (6% chose this)
-
matching circuit for the load (20% chose this)
-
voltage regulator (67% chose this)
-
pi filter (7% chose this)
Which two variables primarily determine the behaviour of an automatic gain control (AGC) loop?
-
Blanking level and slope (3% chose this)
-
Slope and bandwidth (16% chose this)
-
Clipping level and hang time (13% chose this)
-
Threshold and decay time (68% chose this)
What is the output PEP from a transmitter, if an oscilloscope measures 800 volts peak-to-peak across a 50 ohm dummy load connected to the transmitter output?
-
6400 watts (7% chose this)
-
3200 watts (12% chose this)
-
1600 watts (58% chose this)
-
800 watts (22% chose this)
A double conversion receiver designed for SSB reception has a beat frequency oscillator and:
-
one IF stage and one local oscillator (14% chose this)
-
two IF stages and three local oscillators (1% chose this)
-
two IF stages and one local oscillator (24% chose this)
-
two IF stages and two local oscillators (60% chose this)
It is very important that the oscillators contained in a superheterodyne receiver are:
-
sensitive and selective (16% chose this)
-
stable and sensitive (18% chose this)
-
selective and spectrally pure (4% chose this)
-
stable and spectrally pure (62% chose this)
Transmission with SSB, as compared to conventional AM transmission, results in:
-
a greater bandpass requirement in the receiver (10% chose this)
-
3 dB gain in the transmitter (22% chose this)
-
6 dB gain in the transmitter and 3 dB gain in the receiver (58% chose this)
-
6 dB gain in the receiver (10% chose this)
What is the RMS value of a 340 volt peak-to-peak pure sine wave?
-
300 volts (9% chose this)
-
120 volts (59% chose this)
-
170 volts (15% chose this)
-
240 volts (16% chose this)
In a half-wave power supply with a capacitor input filter and a load drawing little or no current, the peak inverse voltage (PIV) across the diode can reach _____ times the RMS voltage.
-
2.8 (55% chose this)
-
0.45 (4% chose this)
-
5.6 (4% chose this)
-
1.4 (38% chose this)
In a high voltage power supply, why should a resistor and capacitor be wired in parallel with the power-supply rectifier diodes?
-
To ensure that the current through each diode is about the same (8% chose this)
-
To equalize voltage drops and guard against transient voltage spikes (55% chose this)
-
To smooth the output waveform (33% chose this)
-
To decrease the output voltage (4% chose this)
When a half-wave dipole antenna is installed one-half wavelength above ground, the:
-
radiation pattern is unaffected (22% chose this)
-
vertical or upward radiation is effectively cancelled (58% chose this)
-
radiation pattern changes to produce side lobes at 15 and 50 degrees (19% chose this)
-
side lobe radiation is cancelled (1% chose this)
Positive feedback from a capacitive divider indicates the oscillator type is:
-
Pierce (21% chose this)
-
Hartley (11% chose this)
-
Miller (5% chose this)
-
Colpitts (63% chose this)
How does a network transform one impedance to another?
-
It cancels the reactive part of an impedance and changes the resistive part (65% chose this)
-
It produces transconductance to cancel the reactive part of an impedance (15% chose this)
-
It introduces negative resistance to cancel the resistive part of an impedance (5% chose this)
-
Network resistances substitute for load resistances (15% chose this)
In a bipolar transistor, the change of collector current with respect to base current is called:
-
delta (9% chose this)
-
alpha (22% chose this)
-
beta (55% chose this)
-
gamma (15% chose this)
A Yagi antenna uses a gamma match. The coaxial braid connects to:
-
the adjustable gamma rod (26% chose this)
-
the centre of the reflector (6% chose this)
-
the centre of the driven element (59% chose this)
-
the variable capacitor (10% chose this)
Which of the following is not a factor affecting the frequency accuracy of a dip meter?
-
Over coupling (8% chose this)
-
Transmitter power output (63% chose this)
-
Hand capacity (22% chose this)
-
Stray capacity (7% chose this)
What is the output waveform of an unfiltered full-wave rectifier connected to a resistive load?
-
A steady DC voltage (16% chose this)
-
A sine wave at half the frequency of the AC input (10% chose this)
-
A series of pulses at the same frequency as the AC input (15% chose this)
-
A series of pulses at twice the frequency of the AC input (59% chose this)
What is meant by circularly polarized electromagnetic waves?
-
Waves with an electric field bent into circular shape (14% chose this)
-
Waves that circle the earth (0% chose this)
-
Waves produced by a circular loop antenna (22% chose this)
-
Waves with a rotating electric field (63% chose this)
What determines the gain of a closed-loop op-amp circuit?
-
The voltage applied to the circuit (23% chose this)
-
The collector-to-base capacitance of the PNP stage (13% chose this)
-
The external feedback network (62% chose this)
-
The PNP collector load (3% chose this)
Carrier suppression in a single-sideband transmitter takes place in:
-
the frequency multiplier stage (16% chose this)
-
the balanced modulator stage (64% chose this)
-
the carrier decouple stage (15% chose this)
-
the mechanical filter (5% chose this)
The reciprocal of the square root of the dielectric constant of the material used to separate the conductors in a transmission line gives the ____________ of the line:
-
impedance (29% chose this)
-
hermetic losses (4% chose this)
-
velocity factor (62% chose this)
-
VSWR (5% chose this)
The BFO is off-set slightly (500 - 1 500 Hz) from the incoming signal to the detector. This is required:
-
to protect the incoming signal from interference (22% chose this)
-
to beat with the incoming signal (67% chose this)
-
to pass the signal without interruption (8% chose this)
-
to provide additional amplification (3% chose this)
The low-level output of a detector is:
-
fed directly to the speaker (4% chose this)
-
applied to the RF amplifier (34% chose this)
-
applied to the AF amplifier (60% chose this)
-
grounded via the chassis (3% chose this)
What happens inside a multimeter when you switch it from a lower to a higher voltage range?
-
Resistance is added in parallel with the meter (22% chose this)
-
Resistance is added in series with the meter (63% chose this)
-
Resistance is reduced in series with the meter (11% chose this)
-
Resistance is reduced in parallel with the meter (4% chose this)
What factors should be considered when selecting an intermediate frequency?
-
Interference to other services (9% chose this)
-
Cross-modulation distortion and interference (14% chose this)
-
Image rejection and responses to unwanted signals (70% chose this)
-
Noise figure and distortion (7% chose this)
What is the Q of a parallel RLC circuit, if it is resonant at 3.625 MHz, L is 3 microhenrys and R is 2.2 kilohms?
-
25.6 (10% chose this)
-
31.1 (24% chose this)
-
0.031 (11% chose this)
-
32.2 (54% chose this)
What is the velocity factor of a transmission line?
-
The velocity of the wave on the transmission line divided by the velocity of light (69% chose this)
-
The velocity of the wave on the transmission line multiplied by the velocity of light in a vacuum (15% chose this)
-
The index of shielding for coaxial cable (1% chose this)
-
The ratio of the characteristic impedance of the line to the terminating impedance (14% chose this)
A device which helps with receiver overload and spurious responses at VHF, UHF and above may be installed in the receiver front end. It is called a:
-
directional coupler (18% chose this)
-
duplexer (17% chose this)
-
helical resonator (55% chose this)
-
diplexer (10% chose this)
An oscilloscope measures 500 volts peak-to-peak across a 50 ohm dummy load connected to the transmitter output during unmodulated carrier conditions. What would an average-reading power meter indicate under the same transmitter conditions?
-
625 watts (65% chose this)
-
427.5 watts (7% chose this)
-
884 watts (11% chose this)
-
442 watts (17% chose this)
What is an operational amplifier (op-amp)?
-
An amplifier used to increase the average output of frequency modulated amateur signals to the legal limit (11% chose this)
-
A program subroutine that calculates the gain of an RF amplifier (1% chose this)
-
A high-gain, direct-coupled differential amplifier whose characteristics are determined by components mounted externally (64% chose this)
-
A high-gain, direct-coupled audio amplifier whose characteristics are determined by internal components of the device (24% chose this)
What is the deviation ratio of an FM phone transmitter having a maximum frequency swing of plus or minus 5 kHz and accepting a maximum modulation rate of 3 kHz?
-
1.66 (69% chose this)
-
60 (3% chose this)
-
0.16 (6% chose this)
-
0.6 (23% chose this)
What is the Q of a parallel RLC circuit, if it is resonant at 3.625 MHz, L is 42 microhenrys and R is 220 ohms?
-
0.00435 (5% chose this)
-
0.23 (58% chose this)
-
2.3 (24% chose this)
-
4.35 (14% chose this)
In a series-regulated power supply, the power dissipation of the pass transistor is:
-
the inverse of the load current and the input/output voltage differential (12% chose this)
-
dependent upon the peak inverse voltage appearing across the Zener diode (11% chose this)
-
indirectly proportional to the load voltage and the input/output voltage differential (10% chose this)
-
directly proportional to the load current and the input/output voltage differential (67% chose this)
A half-wave dipole antenna is normally fed at the point where:
-
the voltage is maximum (12% chose this)
-
the resistance is maximum (4% chose this)
-
the antenna is resonant (18% chose this)
-
the current is maximum (66% chose this)
The amplified IF signal is applied to the ____________ stage in a superheterodyne receiver:
-
LO (12% chose this)
-
detector (66% chose this)
-
RF amplifier (16% chose this)
-
audio output (5% chose this)
For an antenna tuner of the "Series" type, which of the following statements is false?
-
The output is suitable for impedances from low to high (12% chose this)
-
The input is suitable for impedance of 50 ohms (7% chose this)
-
The circuit is known as a Pi-type antenna tuner (67% chose this)
-
The circuit is known as a Series-type antenna tuner (14% chose this)
In a properly designed choke input filter power supply, the no-load voltage across the filter capacitor will be about nine-tenths of the AC RMS voltage; yet it is advisable to use capacitors rated at the peak transformer voltage. Why is this large safety margin suggested?
-
Resonance can be set up in the filter producing high voltages (12% chose this)
-
Under heavy load, high currents and voltages are produced (16% chose this)
-
Under no-load conditions, the current could reach a high level (5% chose this)
-
Under no-load conditions and a burned-out bleeder, voltages could reach the peak transformer voltage (66% chose this)
The FET amplifier common gate circuit is similar to which of the following bipolar transistor amplifier circuits?
-
Common emitter (21% chose this)
-
Common base (58% chose this)
-
Common mode (2% chose this)
-
Common collector (19% chose this)
In a grounded grid amplifier using a triode vacuum tube, each side of the filament is connected to a capacitor whose other end is connected to ground. These are:
-
electrolytic capacitors (5% chose this)
-
blocking capacitors (24% chose this)
-
by-pass capacitors (65% chose this)
-
tuning capacitors (5% chose this)
In a half-wave dipole, where does minimum voltage occur?
-
Both ends (33% chose this)
-
The centre (65% chose this)
-
At the right end (0% chose this)
-
It is equal at all points (1% chose this)
For an antenna tuner of the "Pi" type, which of the following statements is false?
-
The circuit is a Pi-type antenna tuner (12% chose this)
-
The circuit is a series-type antenna tuner (64% chose this)
-
The transmitter input is suitable for impedance of 50 ohms (8% chose this)
-
The antenna output is suitable for impedances from low to high (16% chose this)
What term describes a method of antenna impedance matching that uses a short section of transmission line connected to the antenna transmission line near the antenna and perpendicular to the transmission line?
-
The stub match (68% chose this)
-
The omega match (3% chose this)
-
The delta match (8% chose this)
-
The gamma match (21% chose this)
If a frequency counter with a time base accuracy of +/- 0.1 PPM (parts per million) reads 146 520 000 Hz, what is the most that the actual frequency being measured could differ from that reading?
-
0.1 MHz (9% chose this)
-
1.4652 Hz (8% chose this)
-
1.4652 kHz (17% chose this)
-
14.652 Hz (65% chose this)
What are the principal uses of an op-amp RC active filter in amateur circuitry?
-
Op-amp circuits are used as low-pass filters at the output of transmitters (21% chose this)
-
Op-amp circuits are used as filters for smoothing power supply output (8% chose this)
-
Op-amp circuits are used as high-pass filters to block RFI at the input of receivers (8% chose this)
-
Op-amp circuits are used as audio filters for receivers (64% chose this)
At the ends of a half-wave dipole:
-
voltage and current are both low (8% chose this)
-
voltage is low and current is high (14% chose this)
-
voltage is high and current is low (70% chose this)
-
voltage and current are both high (7% chose this)
What are the advantages of a Darlington pair audio amplifier?
-
Mutual gain, low input impedance and low output impedance (9% chose this)
-
Low output impedance, high mutual impedance and low output current (9% chose this)
-
High gain, high input impedance and low output impedance (63% chose this)
-
Mutual gain, high stability and low mutual inductance (19% chose this)
An oscilloscope cannot be used to:
-
measure DC voltage (18% chose this)
-
determine the amplitude of complex voltage wave forms (7% chose this)
-
determine FM carrier deviation directly (68% chose this)
-
measure frequency (8% chose this)
A superheterodyne receiver designed for SSB reception must have a beat-frequency oscillator (BFO) because:
-
the suppressed carrier must be replaced for detection (68% chose this)
-
it phases out the unwanted sideband signal (14% chose this)
-
it reduces the pass-band of the IF stages (1% chose this)
-
it beats with the receiver carrier to produce the missing sideband (16% chose this)
Which of the following is an important reason for using a VHF intermediate frequency in an HF receiver?
-
To provide a greater tuning range (4% chose this)
-
To tune out cross-modulation distortion (8% chose this)
-
To prevent the generation of spurious mixer products (21% chose this)
-
To move the image response far away from the filter passband (67% chose this)
To compute one of the following, multiply the peak-envelope voltage by 0.707 to obtain the RMS value, square the result and divide by the load resistance. Which is the correct answer?
-
power factor (22% chose this)
-
PEP (63% chose this)
-
PIV (5% chose this)
-
ERP (10% chose this)
For what portion of a signal cycle does a Class C amplifier operate?
-
The entire cycle (14% chose this)
-
180 degrees (20% chose this)
-
Less than 180 degrees (60% chose this)
-
More than 180 degrees but less than 360 degrees (6% chose this)
What is the term used to describe a spread spectrum communications system where the centre frequency of a conventional carrier is changed many times per second in accordance with a pseudorandom list of channels?
-
Time-domain frequency modulation (14% chose this)
-
Frequency companded spread spectrum (10% chose this)
-
Frequency hopping (63% chose this)
-
Direct sequence (14% chose this)
What is the term for the ratio of the radiation resistance of an antenna to the total resistance of the system?
-
Antenna efficiency (62% chose this)
-
Beamwidth (0% chose this)
-
Effective Radiated Power (30% chose this)
-
Radiation conversion loss (9% chose this)
The silicon controlled rectifier (SCR) is a member of which family?
-
Phase locked loops (6% chose this)
-
Varactors (18% chose this)
-
Varistors (16% chose this)
-
Thyristors (60% chose this)
Which component conducts electricity from a negative emitter to a positive collector when its base voltage is made positive?
-
A varactor (4% chose this)
-
A triode vacuum tube (4% chose this)
-
A PNP transistor (34% chose this)
-
An NPN transistor (57% chose this)
How can the accuracy of a frequency counter be improved?
-
By using faster digital logic (16% chose this)
-
By improving the accuracy of the frequency response (17% chose this)
-
By increasing the accuracy of the time base (66% chose this)
-
By using slower digital logic (1% chose this)
What is the output PEP of an unmodulated carrier transmitter if a wattmeter connected to the transmitter output indicates an average reading of 1060 watts?
-
1500 watts (27% chose this)
-
530 watts (3% chose this)
-
1060 watts (59% chose this)
-
2120 watts (10% chose this)
If a 3 dBd gain antenna is replaced with a 9 dBd gain antenna, with no other changes, the Effective Radiated Power (ERP) will increase by:
-
4 (66% chose this)
-
6 (17% chose this)
-
1.5 (8% chose this)
-
2 (9% chose this)
What is the Q of a parallel RLC circuit, if it is resonant at 7.125 MHz, L is 8.2 microhenrys and R is 1 kilohm?
-
2.73 (65% chose this)
-
36.8 (22% chose this)
-
0.368 (6% chose this)
-
0.273 (8% chose this)
What type of semiconductor diode varies its internal capacitance as the voltage applied to its terminals varies?
-
Silicon-controlled rectifier (9% chose this)
-
Hot-carrier (Schottky) (16% chose this)
-
Varactor (54% chose this)
-
Zener (21% chose this)
What is the Q of a parallel RLC circuit, if it is resonant at 14.128 MHz, L is 2.7 microhenrys and R is 18 kilohms?
-
75.1 (56% chose this)
-
7.51 (18% chose this)
-
0.013 (13% chose this)
-
71.5 (13% chose this)
What is the Q of a parallel RLC circuit, if it is resonant at 7.125 MHz, L is 10.1 microhenrys and R is 100 ohms?
-
0.00452 (1% chose this)
-
4.52 (25% chose this)
-
0.221 (57% chose this)
-
22.1 (17% chose this)
What does a product detector do?
-
It amplifies and narrows band-pass frequencies (5% chose this)
-
It detects cross-modulation products (24% chose this)
-
It mixes an incoming signal with a locally generated carrier (65% chose this)
-
It provides local oscillations for input to a mixer (6% chose this)
Most simple horizontally polarized antennas do not exhibit significant directivity unless they are:
-
an eighth of a wavelength above the ground (7% chose this)
-
a quarter wavelength above the ground (19% chose this)
-
three-eighths of a wavelength above the ground (5% chose this)
-
a half wavelength or more above the ground (69% chose this)
What are the majority charge carriers in N-type semiconductor material?
-
Free neutrons (6% chose this)
-
Free electrons (59% chose this)
-
Holes (30% chose this)
-
Free protons (5% chose this)
Poor dynamic range of a receiver can cause many problems when a strong signal appears within or near the front-end bandpass. Which of the following is NOT caused as a direct result?
-
Cross-modulation (12% chose this)
-
Feedback (65% chose this)
-
Desensitization (18% chose this)
-
Intermodulation (5% chose this)
For an antenna tuner of the "Transformer" type, which of the following statements is FALSE?
-
The input is suitable for 50 ohm impedance (9% chose this)
-
The output is suitable for impedances from low to high (12% chose this)
-
The circuit is known as a transformer-type antenna tuner (17% chose this)
-
The circuit is known as a Pi-type antenna tuner (62% chose this)
Which algorithm may be used to create a Cyclic Redundancy Check (CRC)?
-
Convolution code (14% chose this)
-
Lempel-Ziv routine (7% chose this)
-
Hash function (63% chose this)
-
Dynamic Huffman code (16% chose this)
After two time constants, the capacitor in an RC circuit is discharged to what percentage of the starting voltage?
-
13.5% (47% chose this)
-
36.8% (14% chose this)
-
86.5% (25% chose this)
-
63.2% (14% chose this)
What kind of impedance does a quarter wavelength transmission line present to the source when the line is shorted at the far end?
-
A very low impedance (26% chose this)
-
A very high impedance (65% chose this)
-
The same as the characteristic impedance of the transmission line (9% chose this)
-
The same as the output impedance of the source (0% chose this)
Which class of amplifier operates over less than 180 degrees of the cycle?
-
Class C (67% chose this)
-
Class AB (14% chose this)
-
Class A (5% chose this)
-
Class B (14% chose this)
If a 100 Hz signal is fed to the horizontal input of an oscilloscope and a 150 Hz signal is fed to the vertical input, what type of pattern should be displayed on the screen?
-
A looping pattern with 3 horizontal loops, and 2 vertical loops (68% chose this)
-
A rectangular pattern 100 mm wide and 150 mm high (8% chose this)
-
An oval pattern 100 mm wide and 150 mm high (13% chose this)
-
A looping pattern with 100 horizontal loops and 150 vertical loops (12% chose this)
What type of semiconductor material contains more free electrons than pure germanium or silicon crystals?
-
Bipolar (6% chose this)
-
Superconductor (12% chose this)
-
N-type (68% chose this)
-
P-type (14% chose this)
In addition to an input voltage range what are the important characteristics of a three-terminal regulator?
-
Output voltage and minimum output current (8% chose this)
-
Output voltage and maximum output current (66% chose this)
-
Maximum output voltage and minimum output current (15% chose this)
-
Minimum output voltage and maximum output current (11% chose this)
If the incoming signal to the mixer is 3 600 kHz and the first IF is 9 MHz, at which one of the following frequencies would the local oscillator (LO) operate?
-
10 600 kHz (11% chose this)
-
21 600 kHz (11% chose this)
-
5 400 kHz (68% chose this)
-
3 400 kHz (11% chose this)
How is positive feedback coupled to the input in a Pierce oscillator?
-
Through capacitive coupling (63% chose this)
-
Through a neutralizing capacitor (11% chose this)
-
Through link coupling (8% chose this)
-
Through a tapped coil (18% chose this)
Why are received spread-spectrum signals so resistant to interference?
-
The high power used by a spread-spectrum transmitter keeps its signal from being easily overpowered (4% chose this)
-
Signals not using the spectrum-spreading algorithm are suppressed in the receiver (68% chose this)
-
The receiver is always equipped with a special digital signal processor (DSP) interference filter (7% chose this)
-
If interference is detected by the receiver, it will signal the transmitter to change frequencies (21% chose this)
What is meant by the noise floor of a receiver?
-
The weakest signal that can be detected above the receiver internal noise (68% chose this)
-
The weakest signal that can be detected under noisy atmospheric conditions (16% chose this)
-
The minimum level of noise that will overload the receiver RF amplifier stage (6% chose this)
-
The amount of noise generated by the receiver local oscillator (10% chose this)
Crystals are not applicable to which of the following?
-
Lattice filters (8% chose this)
-
Oscillators (5% chose this)
-
Active filters (52% chose this)
-
Microphones (35% chose this)
What is one characteristic of a linear electronic voltage regulator?
-
A pass transistor switches from its "on" state to its "off" state (5% chose this)
-
The control device is switched on or off, with the duty cycle proportional to the line or load conditions (25% chose this)
-
The conduction of a control element is varied in direct proportion to the line voltage or load current (68% chose this)
-
It has a ramp voltage at its output (3% chose this)
In applying Ohm's law to AC circuits, current and voltage values are:
-
average values (13% chose this)
-
average values times 1.414 (3% chose this)
-
none of the proposed answers (16% chose this)
-
peak values times 0.707 (68% chose this)
Why is the Colpitts oscillator circuit commonly used in a VFO?
-
It can be used with or without crystal lock-in (5% chose this)
-
The frequency is a linear function with load impedance (22% chose this)
-
It has high output power (6% chose this)
-
It is stable (67% chose this)
The plane from which ground reflections can be considered to take place, or the effective ground plane for an antenna is:
-
as much as 6 cm below ground depending upon soil conditions (16% chose this)
-
as much as a meter above ground (11% chose this)
-
at ground level exactly (7% chose this)
-
several centimeters to as much as 2 meters below ground, depending upon soil conditions (65% chose this)
In amateur radio equipment, which is the major application for the silicon controlled rectifier (SCR)?
-
Microphone preamplifier circuit (8% chose this)
-
SWR detector circuit (12% chose this)
-
Power supply overvoltage "crowbar" circuit (68% chose this)
-
Class C amplifier circuit (13% chose this)
Why is neutralization necessary for some vacuum-tube amplifiers?
-
To reduce grid-to-cathode leakage (10% chose this)
-
To cancel AC hum from the filament transformer (15% chose this)
-
To reduce the limits of loaded Q (3% chose this)
-
To cancel oscillation caused by the effects of interelectrode capacitance (73% chose this)
You want to convert a surplus parabolic dish for amateur radio use, the gain of this antenna depends on:
-
the material composition of the dish (3% chose this)
-
the diameter of the antenna in wavelengths (73% chose this)
-
the polarization of the feed device illuminating it (1% chose this)
-
the focal length of the antenna (23% chose this)
What is the Q of a parallel RLC circuit, if it is resonant at 14.128 MHz, L is 4.7 microhenrys and R is 18 kilohms?
-
43.1 (64% chose this)
-
13.3 (13% chose this)
-
0.023 (8% chose this)
-
4.31 (14% chose this)
What type of polarization is produced by crossed dipoles fed 90 degrees out of phase?
-
Circular polarization (65% chose this)
-
Cross-polarization (18% chose this)
-
Perpendicular polarization (4% chose this)
-
None of the other answers, the two fields cancel out (13% chose this)
How is the positive feedback coupled to the input in a Hartley oscillator?
-
Through link coupling (12% chose this)
-
Through a neutralizing capacitor (10% chose this)
-
Through a tapped coil (64% chose this)
-
Through a capacitive divider (14% chose this)
Which type of network offers the greatest transformation ratio?
-
Chebyshev (11% chose this)
-
Butterworth (5% chose this)
-
L-network (14% chose this)
-
Pi-network (70% chose this)
The lower the receiver noise figure becomes, the greater will be the receiver's _________:
-
sensitivity (72% chose this)
-
rejection of unwanted signals (9% chose this)
-
selectivity (15% chose this)
-
stability (4% chose this)
In an FM phone signal having a maximum frequency deviation of 3000 Hz either side of the carrier frequency, what is the modulation index, when the modulating frequency is 1000 Hz?
-
0.3 (21% chose this)
-
3000 (7% chose this)
-
1000 (3% chose this)
-
3 (70% chose this)
For a 3-element Yagi antenna with horizontally mounted elements, how does the main lobe takeoff angle vary with height above flat ground?
-
It does not vary with height (8% chose this)
-
It depends on E-region height, not antenna height (8% chose this)
-
It decreases with increasing height (70% chose this)
-
It increases with increasing height (14% chose this)
Why is a resistor often included in a parallel resonant circuit?
-
To increase the Q and decrease bandwidth (23% chose this)
-
To decrease the Q and increase the bandwidth (62% chose this)
-
To increase the Q and decrease the skin effect (6% chose this)
-
To decrease the Q and increase the resonant frequency (9% chose this)
The output tuning controls on a transmitter power amplifier with an adjustable PI network:
-
allow switching to different antennas (3% chose this)
-
reduce the possibility of cross-modulation in adjunct receivers (16% chose this)
-
are involved with frequency multiplication in the previous stage (11% chose this)
-
allow efficient transfer of power to the antenna (71% chose this)
How is the output Peak-Envelope Power of a transmitter calculated if an oscilloscope is used to measure the Peak-Envelope Voltage across a dummy resistive load (where PEP = Peak-Envelope Power, PEV = Peak-Envelope Voltage, Vp = peak-voltage, RL = load resistance)?
-
PEP = [(1.414 PEV)(1.414 PEV)] / RL (15% chose this)
-
PEP = [(0.707 PEV)(0.707 PEV)] / RL (64% chose this)
-
PEP = [(Vp)(Vp)] / (RL) (18% chose this)
-
PEP = (Vp)(Vp)(RL) (2% chose this)
In a multivibrator circuit, when one transistor conducts, the other is:
-
saturated (7% chose this)
-
reverse-biased (17% chose this)
-
forward-biased (12% chose this)
-
cut off (64% chose this)
What is the best instrument to use to check the signal quality of a CW or single-sideband phone transmitter?
-
A signal tracer and an audio amplifier (6% chose this)
-
A field-strength meter (7% chose this)
-
An oscilloscope (76% chose this)
-
A sidetone monitor (11% chose this)
The bandwidth of an oscilloscope is:
-
a function of the time-base accuracy (21% chose this)
-
the highest frequency signal the scope can display (69% chose this)
-
directly related to gain compression (9% chose this)
-
indirectly related to screen persistence (1% chose this)
What are the advantages of the frequency conversion process in a superheterodyne receiver?
-
Automatic soft-limiting and automatic squelching (1% chose this)
-
Automatic squelching and increased sensitivity (7% chose this)
-
Increased selectivity and optimal tuned circuit design (74% chose this)
-
Automatic detection in the RF amplifier and increased sensitivity (18% chose this)
What is meant by the radiation resistance of an antenna?
-
The equivalent resistance that would dissipate the same amount of power as that radiated from an antenna (68% chose this)
-
The resistance in the atmosphere that an antenna must overcome to be able to radiate a signal (11% chose this)
-
The specific impedance of an antenna (6% chose this)
-
The combined losses of the antenna elements and transmission line (14% chose this)
What is the undesirable result of AF clipping in a speech processor?
-
Reduction in peak amplitude (17% chose this)
-
Increased harmonic distortion (72% chose this)
-
Reduced average power (11% chose this)
-
Increased average power (0% chose this)
AC voltmeter scales are usually calibrated to read:
-
peak voltage (8% chose this)
-
instantaneous voltage (4% chose this)
-
average voltage (14% chose this)
-
RMS voltage (74% chose this)
In an oscillator where positive feedback is provided through a capacitor in series with a crystal, that type of oscillator is a:
-
Pierce (61% chose this)
-
Colpitts (31% chose this)
-
Hartley (2% chose this)
-
Franklin (6% chose this)
A transmitter has an output of 2000 watts PEP. The transmission line, connectors and antenna tuner have a composite loss of 1 dB, and the gain from the stacked Yagi antenna is 10 dBd. What is the Effective Radiated Power (ERP) in watts PEP?
-
2009 (0% chose this)
-
16 000 (73% chose this)
-
18 000 (20% chose this)
-
20 000 (7% chose this)
Where should an RF wattmeter be connected for the most accurate readings of transmitter output power?
-
One-half wavelength from the transmitter output (9% chose this)
-
One-half wavelength from the antenna feed point (3% chose this)
-
At the antenna feed point (20% chose this)
-
At the transmitter output connector (68% chose this)
Which of the following functions is not included in a typical digital signal processor?
-
Mathematical transform (15% chose this)
-
Aliasing amplifier (68% chose this)
-
Analog to digital converter (6% chose this)
-
Digital to analog converter (10% chose this)
Open Systems Interconnection (OSI) model standardizes communications functions as layers within a data communications system. Amateur digital radio systems often follow the OSI model in structure. What is the base layer of the OSI model involving the interconnection of a packet radio TNC to a computer terminal?
-
The physical layer (65% chose this)
-
The link layer (17% chose this)
-
The network layer (11% chose this)
-
The transport layer (7% chose this)
Speech compression associated with SSB transmission implies:
-
a lower signal-to-noise ratio (10% chose this)
-
circuit level instability (0% chose this)
-
full amplification of low level signals and reducing or eliminating amplification of high level signals (69% chose this)
-
full amplification of high level signals and reducing or eliminating signals amplification of low level (21% chose this)
How many bits are required to provide 256 discrete levels, or a ratio of 256:1?
-
6 bits (3% chose this)
-
16 bits (24% chose this)
-
4 bits (3% chose this)
-
8 bits (71% chose this)
What is a common use for point contact diodes?
-
As a constant current source (5% chose this)
-
As a constant voltage source (10% chose this)
-
As a high voltage rectifier (16% chose this)
-
As an RF detector (69% chose this)
In a half-wave dipole, the distribution of _______ is lowest at each end.
-
capacitance (4% chose this)
-
current (69% chose this)
-
voltage (20% chose this)
-
inductance (8% chose this)
What is one common use for PIN diodes?
-
As a constant current source (6% chose this)
-
As a high voltage rectifier (20% chose this)
-
As a constant voltage source (10% chose this)
-
As an RF switch (64% chose this)
The feed point in a centre-fed half-wave antenna is at the point of:
-
minimum voltage and current (9% chose this)
-
maximum voltage (12% chose this)
-
maximum current (73% chose this)
-
minimum current (5% chose this)
What are the two stable operating conditions of a silicon controlled rectifier (SCR)?
-
NPN conduction and PNP conduction (16% chose this)
-
Oscillating and quiescent (1% chose this)
-
Conducting and non-conducting (59% chose this)
-
Forward conducting and reverse conducting (24% chose this)
What is the purpose of a Cyclic Redundancy Check (CRC)?
-
Lossy compression (1% chose this)
-
Error correction (24% chose this)
-
Lossless compression (0% chose this)
-
Error detection (74% chose this)
What is the resonant frequency of a parallel RLC circuit if R is 4.7 kilohms, L is 200 microhenrys and C is 10 picofarads?
-
7.96 kHz (2% chose this)
-
3.56 MHz (67% chose this)
-
3.56 kHz (10% chose this)
-
7.96 MHz (21% chose this)
What is a NAND gate?
-
A circuit that produces a logic "1" at its output only when all inputs are logic "1" (13% chose this)
-
A circuit that produces a logic "0" at its output if some but not all of its inputs are logic "1" (18% chose this)
-
A circuit that produces a logic "0" at its output only when all inputs are logic "0" (7% chose this)
-
A circuit that produces a logic "0" at its output only when all inputs are logic "1" (62% chose this)
What is the modulation index of an FM phone transmitter producing an instantaneous carrier deviation of 6 kHz when modulated with a 2 kHz modulating frequency?
-
3 (79% chose this)
-
0.333 (14% chose this)
-
2000 (6% chose this)
-
6000 (1% chose this)
Which of the following is NOT a valid parabolic dish illumination arrangement?
-
Offset feed (7% chose this)
-
Cassegrain (20% chose this)
-
Newtonian (68% chose this)
-
Front feed (5% chose this)
A transmitter has an output of 1000 watts PEP. The coaxial cable, connectors and antenna tuner have a composite loss of 1 dB, and the antenna gain is 10 dBd. What is the Effective Radiated Power (ERP) in watts PEP?
-
8000 (77% chose this)
-
1009 (4% chose this)
-
10 000 (3% chose this)
-
9000 (15% chose this)
A multiple conversion superheterodyne receiver is more susceptible to spurious responses than a single-conversion receiver because of the:
-
additional oscillators and mixing frequencies involved in the design (72% chose this)
-
poorer selectivity in the IF caused by the multitude of frequency changes (9% chose this)
-
greater sensitivity introducing higher levels of RF to the receiver (16% chose this)
-
AGC being forced to work harder causing the stages concerned to overload (3% chose this)
The ripple frequency produced by a half-wave power supply connected to a normal household circuit is:
-
60 Hz (66% chose this)
-
90 Hz (0% chose this)
-
120 Hz (29% chose this)
-
30 Hz (5% chose this)
How can a single-sideband phone signal be produced?
-
By using a loop modulator followed by a mixer (6% chose this)
-
By using a reactance modulator followed by a mixer (6% chose this)
-
By using a balanced modulator followed by a filter (77% chose this)
-
By driving a product detector with a DSB signal (11% chose this)
The impedance at the centre of a dipole antenna more than 3 wavelengths above ground would be nearest to:
-
300 ohms (18% chose this)
-
600 ohms (9% chose this)
-
75 ohms (69% chose this)
-
25 ohms (5% chose this)
What is one advantage of using ASCII rather than Baudot code?
-
It includes both upper and lower case text characters in the code (79% chose this)
-
ASCII includes built-in error correction (13% chose this)
-
ASCII characters contain fewer information bits (4% chose this)
-
The larger character set allows store-and-forward (4% chose this)
What type of semiconductor material contains fewer free electrons than pure germanium or silicon crystals?
-
N-type (15% chose this)
-
Bipolar type (9% chose this)
-
Superconductor type (14% chose this)
-
P-type (63% chose this)
What is the best signal source to connect to the vertical input of an oscilloscope for checking the quality of a transmitted signal?
-
The IF output of a monitoring receiver (11% chose this)
-
The audio input of the transmitter (6% chose this)
-
The RF output of the transmitter through a sampling device (76% chose this)
-
The RF signals of a nearby receiving antenna (7% chose this)
Assuming a velocity factor of 0.66 what would be the physical length of a typical coaxial stub that is electrically one quarter wavelength long at 14.1 MHz?
-
2.33 metres (7.64 feet) (11% chose this)
-
0.25 metre (0.82 foot) (5% chose this)
-
3.51 metres (11.5 feet) (68% chose this)
-
20 metres (65.6 feet) (16% chose this)
What are the two major ratings that must not be exceeded for silicon-diode rectifiers used in power-supply circuits?
-
Average power; average voltage (4% chose this)
-
Capacitive reactance; avalanche voltage (5% chose this)
-
Peak load impedance; peak voltage (19% chose this)
-
Peak inverse voltage; average forward current (71% chose this)
In a half-wave dipole, where does the minimum current occur?
-
At the centre (19% chose this)
-
It is equal at all points (4% chose this)
-
At the right end (4% chose this)
-
At both ends (73% chose this)
What is meant by "flat topping" in a single-sideband phone transmission?
-
The transmitter's carrier is properly suppressed (6% chose this)
-
Signal distortion caused by excessive drive (82% chose this)
-
Signal distortion caused by insufficient collector current (4% chose this)
-
The transmitter's automatic level control is properly adjusted (7% chose this)
You want to calibrate your station frequency reference to the WWV signal on your receiver. The resulting beat tone must be:
-
a combined frequency above both (21% chose this)
-
the mathematical mean of both frequencies (8% chose this)
-
at the highest audio frequency possible (3% chose this)
-
of a frequency as low as possible and with a period as long as possible (69% chose this)
When a silicon controlled rectifier (SCR) is triggered, to what other semiconductor diode are its electrical characteristics similar (as measured between its cathode and anode)?
-
The PIN diode (7% chose this)
-
The hot-carrier (Schottky) diode (16% chose this)
-
The varactor diode (16% chose this)
-
The junction diode (60% chose this)
In a regulated power supply, a diode connected across the input and output terminals of a regulator is used to:
-
protect the regulator from reverse voltages (73% chose this)
-
provide an RF by-pass for the voltage control (4% chose this)
-
provide additional capacity (0% chose this)
-
protect the regulator from voltage fluctuations in the primary of the transformer (23% chose this)
The driven element of a Yagi antenna is connected to a coaxial transmission line. The coax braid is connected to the centre of the driven element and the centre conductor is connected to a variable capacitor in series with an adjustable mechanical arrangement on one side of the driven element. The type of matching is:
-
zeta match (1% chose this)
-
gamma match (76% chose this)
-
lambda match (9% chose this)
-
T match (14% chose this)
Piezoelectricity is generated by:
-
touching crystals with magnets (5% chose this)
-
adding impurities to a crystal (16% chose this)
-
moving a magnet near a crystal (11% chose this)
-
deforming certain crystals (68% chose this)
In a half-wave dipole, the lowest distribution of _________ occurs at the middle.
-
voltage (70% chose this)
-
capacity (4% chose this)
-
inductance (10% chose this)
-
current (16% chose this)
A Smith Chart is useful:
-
to solve problems in direct current circuits (9% chose this)
-
because it only works with complex numbers (4% chose this)
-
because it simplifies mathematical operations (74% chose this)
-
only to solve matching and transmission line problems (13% chose this)
When the transmitter is not modulated, or the amplitude of the modulating signal is zero, the frequency of the carrier is called its:
-
modulating frequency (12% chose this)
-
centre frequency (81% chose this)
-
frequency deviation (4% chose this)
-
frequency shift (3% chose this)
A single conversion receiver with a 9 MHz IF has a local oscillator operating at 16 MHz. The frequency it is tuned to is:
-
7 MHz (77% chose this)
-
16 MHz (11% chose this)
-
21 MHz (8% chose this)
-
9 MHz (4% chose this)
What is a pi-network?
-
A network consisting of one inductor and two capacitors or two inductors and one capacitor (78% chose this)
-
An antenna matching network that is isolated from ground (8% chose this)
-
A network consisting of four inductors or four capacitors (10% chose this)
-
A power incidence network (4% chose this)
What is the term used for an equivalent resistance which would dissipate the same amount of energy as that radiated from an antenna?
-
j factor (6% chose this)
-
Antenna resistance (17% chose this)
-
K factor (5% chose this)
-
Radiation resistance (72% chose this)
Why is a ground-mounted vertical quarter-wave antenna in reasonably open surroundings better for long distance contacts than a half-wave dipole at a quarter wavelength above ground?
-
It has an omnidirectional characteristic (17% chose this)
-
It uses vertical polarization (3% chose this)
-
The vertical radiation angle is lower (75% chose this)
-
The radiation resistance is lower (5% chose this)
What is the output impedance of a theoretically ideal op-amp?
-
Very high (25% chose this)
-
Exactly 100 ohms (1% chose this)
-
Exactly 1000 ohms (0% chose this)
-
Very low (74% chose this)
What is the deviation ratio of an FM phone transmitter having a maximum frequency swing of plus or minus 7.5 kHz and accepting a maximum modulation rate of 3.5 kHz?
-
0.47 (19% chose this)
-
47 (4% chose this)
-
0.214 (5% chose this)
-
2.14 (72% chose this)
The dial calibration on the output attenuator of a signal generator:
-
reads half the true output when the attenuator is properly terminated (1% chose this)
-
reads accurately only when the attenuator is properly terminated (72% chose this)
-
always reads the true output of the signal generator (19% chose this)
-
reads twice the true output when the attenuator is properly terminated (8% chose this)
One of the greatest advantages of the double-conversion over the single-conversion receiver is that it:
-
is much more stable (11% chose this)
-
is much more sensitive (11% chose this)
-
produces a louder signal at the output (4% chose this)
-
greater reduction of image interference for a given front end selectivity (75% chose this)
On VHF/UHF frequencies, Doppler shift becomes of consequence on which type of communication?
-
Simplex line-of-sight contact between hand-held transceivers (13% chose this)
-
Contact with terrestrial mobile stations (6% chose this)
-
Contact via satellite (81% chose this)
-
Contact through a hilltop repeater (0% chose this)
The term which relates specifically to the amplitude levels of multiple signals that can be accommodated during reception is called:
-
noise figure (8% chose this)
-
dynamic range (72% chose this)
-
AGC (10% chose this)
-
cross-modulation index (10% chose this)
How does the input impedance of a field-effect transistor (FET) compare with that of a bipolar transistor?
-
An FET has high input impedance; a bipolar transistor has low input impedance (62% chose this)
-
One cannot compare input impedance without knowing supply voltage (4% chose this)
-
An FET has low input impedance; a bipolar transistor has high input impedance (31% chose this)
-
The input impedance of FETs and bipolar transistors is the same (3% chose this)
What is the resonant frequency of a series RLC circuit, if R is 47 ohms, L is 8 microhenrys and C is 7 picofarads?
-
2.13 MHz (17% chose this)
-
21.3 MHz (62% chose this)
-
28.4 MHz (17% chose this)
-
2.84 MHz (4% chose this)
What determines the velocity factor in a transmission line?
-
Dielectrics in the line (73% chose this)
-
The line length (4% chose this)
-
The centre conductor resistivity (16% chose this)
-
The terminal impedance (8% chose this)
What is the value of inductance (L) in a parallel RLC circuit, if the resonant frequency is 14.25 MHz and C is 44 picofarads?
-
0.353 microhenry (8% chose this)
-
2.8 microhenrys (66% chose this)
-
253.8 millihenrys (6% chose this)
-
3.9 millihenrys (20% chose this)
When using a choke input filter, a minimum current should be drawn all the time when the device is switched on. This can be accomplished by:
-
placing an ammeter in the output circuit (1% chose this)
-
increasing the value of the output capacitor (12% chose this)
-
including a suitable bleeder resistance (77% chose this)
-
utilizing a full-wave bridge rectifier circuit (10% chose this)
What is the resonant frequency of a parallel RLC circuit if R is 4.7 kilohms, L is 90 microhenrys and C is 100 picofarads?
-
1.68 MHz (67% chose this)
-
1.77 kHz (1% chose this)
-
1.77 MHz (26% chose this)
-
1.68 kHz (6% chose this)
In a frequency multiplier circuit, an inductance (L1) and a variable capacitor (C2) are connected in series between VCC+ and ground. The collector of a transistor is connected to a tap on L1. C2 in conjunction with L1 operate as a:
-
voltage doubler (13% chose this)
-
frequency multiplier (68% chose this)
-
frequency divider (5% chose this)
-
voltage divider (13% chose this)
What is the traditional way of verifying the accuracy of a crystal calibrator?
-
Compare the oscillator with your transmitter (3% chose this)
-
Use a dip-meter to determine the oscillator's fundamental frequency (21% chose this)
-
Compare the oscillator with your receiver (0% chose this)
-
Zero-beat the crystal oscillator against a standard frequency station such as WWV (76% chose this)
What is one way receiver desensitization can be reduced?
-
Increase the transmitter audio gain (3% chose this)
-
Use a cavity filter (65% chose this)
-
Decrease the receiver squelch gain (19% chose this)
-
Increase the receiver bandwidth (13% chose this)
In a simple 2 stage CW transmitter, the transistor in the second stage would act as:
-
the master oscillator (4% chose this)
-
an audio oscillator (3% chose this)
-
a power amplifier (79% chose this)
-
a frequency multiplier (14% chose this)
A transmitter has a power output of 125 watts. There is a loss of 0.8 dB in the transmission line, 0.2 dB in the antenna tuner, and a gain of 10 dBd in the antenna. The Effective Radiated Power (ERP) is:
-
1250 (4% chose this)
-
1125 (17% chose this)
-
134 (9% chose this)
-
1000 (70% chose this)
What is an EXCLUSIVE OR gate?
-
A circuit that produces a logic "1" at its output when all of the inputs are logic "1" (14% chose this)
-
A circuit that produces a logic "1" at its output when all of the inputs are logic "0" (4% chose this)
-
A circuit that produces a logic "1" at its output when only one of the inputs is logic "1" (67% chose this)
-
A circuit that produces a logic "0" at its output when only one of the inputs is logic "1" (15% chose this)
What digital code consists of elements having unequal length?
-
Baudot (15% chose this)
-
ASCII (4% chose this)
-
Varicode (78% chose this)
-
AX.25 (3% chose this)
The mixer stage of a superheterodyne receiver is used to:
-
change the frequency of the incoming signal to that of the IF (75% chose this)
-
allow a number of IF frequencies to be used (12% chose this)
-
remove image signals from the receiver (7% chose this)
-
produce an audio frequency for the speaker (7% chose this)
What is the time constant of a circuit having a 100 microfarad capacitor in series with a 470 kilohm resistor?
-
470 seconds (7% chose this)
-
0.47 seconds (28% chose this)
-
47 seconds (59% chose this)
-
4700 seconds (6% chose this)
If the peak value of a 100 Hz sinusoidal waveform is 20 volts, the RMS value is:
-
7.07 volts (9% chose this)
-
16.38 volts (15% chose this)
-
14.14 volts (70% chose this)
-
28.28 volts (6% chose this)
What is the Q of a parallel RLC circuit, if it is resonant at 3.625 MHz, L is 43 microhenrys and R is 1.8 kilohms?
-
0.543 (7% chose this)
-
54.3 (16% chose this)
-
23 (13% chose this)
-
1.84 (65% chose this)
If the ohmic resistance of a half-wave dipole is 2 ohms, and the radiation resistance is 72 ohms, what is the antenna efficiency?
-
72% (11% chose this)
-
100% (4% chose this)
-
97.3% (68% chose this)
-
74% (18% chose this)
A sine wave of 17 volts peak is equivalent to how many volts RMS?
-
24 volts (7% chose this)
-
34 volts (9% chose this)
-
8.5 volts (8% chose this)
-
12 volts (76% chose this)
What is the meaning of the term "time constant" in an RL circuit?
-
The time required for the current in the circuit to build up to 36.8% of the maximum value (10% chose this)
-
The time required for the voltage in the circuit to build up to 63.2% of the maximum value (37% chose this)
-
The time required for the voltage in the circuit to build up to 36.8% of the maximum value (4% chose this)
-
The time required for the current in the circuit to build up to 63.2% of the maximum value (50% chose this)
The mixer stage of a superheterodyne receiver:
-
acts as a buffer stage (6% chose this)
-
demodulates SSB signals (10% chose this)
-
produces an intermediate frequency (83% chose this)
-
produces spurious signals (1% chose this)
If the ohmic resistance of a miniloop antenna is 2 milliohms and the radiation resistance is 50 milliohms, what is the antenna efficiency?
-
96.15% (73% chose this)
-
52% (8% chose this)
-
25% (15% chose this)
-
50% (4% chose this)
Which filter type is described as having ripple in the passband and a sharp cutoff?
-
A Butterworth filter (17% chose this)
-
A Chebyshev filter (70% chose this)
-
An active LC filter (10% chose this)
-
A passive op-amp filter (2% chose this)
What is printed circuit transmission line called?
-
Ground plane (3% chose this)
-
Microstripline (75% chose this)
-
Dielectric substrate (7% chose this)
-
Dielectric imprinting (16% chose this)
Peak-Envelope Power (PEP) for SSB transmission is:
-
a hypothetical measurement (5% chose this)
-
Peak-Envelope Voltage (PEV) multiplied by 0.707, squared and divided by the load resistance (76% chose this)
-
peak-voltage multiplied by peak current (11% chose this)
-
equal to the RMS power (8% chose this)
In a half-wave dipole, where does the minimum impedance occur?
-
At both ends (21% chose this)
-
At the centre (71% chose this)
-
It is the same at all points (9% chose this)
-
At the right end (0% chose this)
How can the approximate beamwidth of a beam antenna be determined?
-
Measure the ratio of the signal strengths of the radiated power lobes from the front and side of the antenna (9% chose this)
-
Measure the ratio of the signal strengths of the radiated power lobes from the front and rear of the antenna (9% chose this)
-
Note the two points where the signal strength is down 3 dB from the maximum signal point and compute the angular difference (74% chose this)
-
Draw two imaginary lines through the ends of the elements and measure the angle between the lines (8% chose this)
For what portion of a cycle does a Class AB amplifier operate?
-
Exactly 180 degrees (5% chose this)
-
The entire cycle (12% chose this)
-
Less than 180 degrees (8% chose this)
-
More than 180 degrees but less than 360 degrees (75% chose this)
What term describes a wide-band communications system in which the RF carrier varies according to some predetermined sequence?
-
Time domain frequency modulation (9% chose this)
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Spread spectrum communication (78% chose this)
-
Amplitude-companded single sideband (1% chose this)
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AMTOR (11% chose this)
What are the three terminals of a silicon controlled rectifier (SCR)?
-
Gate, base 1 and base 2 (5% chose this)
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Base, collector and emitter (24% chose this)
-
Gate, source and sink (5% chose this)
-
Anode, cathode and gate (67% chose this)
Hole conduction in a p-channel enhancement type MOSFET is associated with:
-
n-channel depletion (16% chose this)
-
n-channel enhancement (10% chose this)
-
q-channel depletion (0% chose this)
-
p-channel enhancement (73% chose this)
What factor determines the bandwidth and response shape of a crystal lattice filter?
-
The gain of the RF stage following the filter (4% chose this)
-
The amplitude of the signals passing through the filter (9% chose this)
-
The relative frequencies of the individual crystals (74% chose this)
-
The centre frequency chosen for the filter (13% chose this)
Effective Radiated Power means the:
-
transmitter output power, minus line losses, plus antenna gain relative to a dipole (77% chose this)
-
power supplied to the antenna before the modulation of the carrier (3% chose this)
-
power supplied to the transmission line plus antenna gain (9% chose this)
-
ratio of signal output power to signal input power (11% chose this)
What are the two basic types of junction field-effect transistors (JFET)?
-
N-channel and P-channel (71% chose this)
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High power and low power (0% chose this)
-
MOSFET and GaAsFET (20% chose this)
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Silicon and germanium (10% chose this)
What does a frequency counter do?
-
It generates broad-band white noise for calibration (4% chose this)
-
It produces a reference frequency (11% chose this)
-
It makes frequency measurements (72% chose this)
-
It measures frequency deviation (14% chose this)
What is the value of capacitance (C) in a series R-L-C circuit, if the circuit resonant frequency is 14.25 MHz and L is 2.84 microhenrys?
-
44 microfarads (13% chose this)
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2.2 picofarads (9% chose this)
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44 picofarads (68% chose this)
-
2.2 microfarads (9% chose this)
What is the resonant frequency of a series RLC circuit, if R is 47 ohms, L is 25 microhenrys and C is 10 picofarads?
-
63.7 MHz (16% chose this)
-
10.1 kHz (7% chose this)
-
63.7 kHz (8% chose this)
-
10.1 MHz (68% chose this)
What is a signal generator?
-
A low-stability oscillator used to inject a signal into a circuit under test (4% chose this)
-
A high-stability oscillator which generates reference signals at exact frequency intervals (21% chose this)
-
A high-stability oscillator which can produce a wide range of frequencies and amplitudes (75% chose this)
-
A low-stability oscillator which sweeps through a range of frequencies (0% chose this)
How much gain should be used in the RF amplifier stage of a receiver?
-
Sufficient gain to allow weak signals to overcome noise generated in the first mixer stage (84% chose this)
-
As much gain as possible, short of self-oscillation (4% chose this)
-
It depends on the amplification factor of the first IF stage (1% chose this)
-
Sufficient gain to keep weak signals below the noise of the first mixer stage (10% chose this)
The effective value of a sine wave of voltage or current is:
-
50% of the maximum value (6% chose this)
-
100% of the maximum value (8% chose this)
-
63.6% of the maximum value (10% chose this)
-
70.7% of the maximum value (75% chose this)
The formula to be used to calculate the power output of a transmitter into a resistor load using a voltmeter is:
-
P = EI/R (21% chose this)
-
P = EI cos 0 (2% chose this)
-
P = IR (10% chose this)
-
P = E2 /R (67% chose this)
Why is an L-network of limited utility in impedance matching?
-
It has limited power handling capability (16% chose this)
-
It matches only a small impedance range (67% chose this)
-
It is thermally unstable (2% chose this)
-
It is prone to self-resonance (14% chose this)
What circuit combines signals from an IF amplifier stage and a beat-frequency oscillator (BFO), to produce an audio signal?
-
A VFO circuit (15% chose this)
-
A product detector circuit (73% chose this)
-
An AGC circuit (9% chose this)
-
A power supply circuit (4% chose this)
What is the resonant frequency of a parallel RLC circuit if R is 4.7 kilohms, L is 10 microhenrys and C is 50 picofarads?
-
7.12 kHz (6% chose this)
-
3.18 MHz (21% chose this)
-
3.18 kHz (4% chose this)
-
7.12 MHz (69% chose this)
How does the spread-spectrum technique of frequency hopping work?
-
The frequency of an RF carrier is changed very rapidly according to a particular pseudo-random sequence (79% chose this)
-
If interference is detected by the receiver, it will signal the transmitter to change frequency (4% chose this)
-
If interference is detected by the receiver, it will signal the transmitter to wait until the frequency is clear (0% chose this)
-
A pseudo-random bit stream is used to shift the phase of an RF carrier very rapidly in a particular sequence (17% chose this)
The regulation of short-term changes in the load resistance of a power supply is called:
-
dynamic regulation (75% chose this)
-
static regulation (15% chose this)
-
analog regulation (0% chose this)
-
active regulation (10% chose this)
The sensitivity of an ammeter is an expression of:
-
the amount of current causing full-scale deflection (66% chose this)
-
the resistance of the meter (13% chose this)
-
the loading effect the meter will have on a circuit (11% chose this)
-
the value of the shunt resistor (9% chose this)
What is the term used for the decibel difference (or ratio) between the largest tolerable receiver input signal (without causing audible distortion products) and the minimum discernible signal (sensitivity)?
-
Stability (3% chose this)
-
Noise figure (16% chose this)
-
Dynamic range (80% chose this)
-
Design parameter (1% chose this)
A helical-beam antenna with right-hand polarization will best receive signals with:
-
left-hand polarization (9% chose this)
-
vertical polarization only (3% chose this)
-
horizontal polarization (3% chose this)
-
right-hand polarization (86% chose this)
You can use an oscilloscope to display the input and output of a circuit at the same time by:
-
measuring the input on the X axis and the output on the Y axis (23% chose this)
-
measuring the input on the X axis and the output on the Z axis (4% chose this)
-
measuring the input on the Y axis and the output on the X axis (2% chose this)
-
utilizing a dual trace oscilloscope (71% chose this)
A dip meter supplies the radio frequency energy which enables you to check:
-
the adjustment of an inductor (1% chose this)
-
the resonant frequency of a circuit (88% chose this)
-
the calibration of an absorption-type wavemeter (4% chose this)
-
the impedance mismatch in a circuit (6% chose this)
What is a crystal lattice filter?
-
A filter with narrow bandwidth and steep skirts made using quartz crystals (71% chose this)
-
A filter with wide bandwidth and shallow skirts made using quartz crystals (14% chose this)
-
An audio filter made with four quartz crystals that resonate at 1 kHz intervals (10% chose this)
-
A power supply filter made with interlaced quartz crystals (5% chose this)
Which class of amplifier provides the least efficiency?
-
Class AB (2% chose this)
-
Class A (69% chose this)
-
Class C (28% chose this)
-
Class B (1% chose this)
On VHF and above, 1/4 wavelength coaxial cavities are used to give protection from high-level signals. For a frequency of approximately 50 MHz, the diameter of such a device would be about 10 cm (4 in). What would be its approximate length?
-
0.6 metres (2 ft) (15% chose this)
-
2.4 metres (8 ft) (11% chose this)
-
3.7 metres (12 ft) (12% chose this)
-
1.5 metres (5 ft) (63% chose this)
What is the Effective Radiated Power of an amateur transmitter, if the transmitter output power is 200 watts, the transmission line loss is 5 watts, and the antenna power gain is 3 dBd?
-
390 watts (82% chose this)
-
197 watts (7% chose this)
-
228 watts (8% chose this)
-
178 watts (3% chose this)
Waveguide is typically used:
-
at frequencies above 3000 MHz (77% chose this)
-
at frequencies above 2 MHz (9% chose this)
-
at frequencies below 150 MHz (6% chose this)
-
at frequencies below 1500 MHz (8% chose this)
Full-wave voltage doublers:
-
use both halves of an AC wave (75% chose this)
-
create four times the output voltage of half-wave doublers (16% chose this)
-
use less power than half-wave doublers (8% chose this)
-
are used only in high-frequency power supplies (1% chose this)
What audio frequencies are used in a two-tone test of the linearity of a single-sideband phone transmitter?
-
Any two audio tones may be used, but they must be within the transmitter audio passband, and should not be harmonically related (82% chose this)
-
20 Hz and 20 kHz tones must be used (3% chose this)
-
1200 Hz and 2400 Hz tones must be used (3% chose this)
-
Any two audio tones may be used, but they must be within the transmitter audio passband, and must be harmonically related (12% chose this)
Which of the following classes of amplifier would provide the highest efficiency in the output stage of a CW, RTTY or FM transmitter?
-
Class C (78% chose this)
-
Class AB (10% chose this)
-
Class B (4% chose this)
-
Class A (8% chose this)
What two ways could a dip meter be used in an amateur station?
-
To measure antenna resonance and percentage modulation (8% chose this)
-
To measure resonant frequency of antenna traps and percentage modulation (5% chose this)
-
To measure resonant frequencies of antenna traps and to measure a tuned circuit resonant frequency (79% chose this)
-
To measure antenna resonance and impedance (8% chose this)
The advantage of a double conversion receiver over a single conversion receiver is that it:
-
produces a louder audio signal (0% chose this)
-
suffers less from image interference for a given front end sensitivity (81% chose this)
-
does not drift off frequency (1% chose this)
-
is a more sensitive receiver (18% chose this)
Which of the following filter types is not suitable for use at audio and low radio frequencies?
-
Elliptical (12% chose this)
-
Chebyshev (17% chose this)
-
Butterworth (1% chose this)
-
Cavity (70% chose this)
What receiver stage combines a 14.25-MHz input signal with a 13.795-MHz oscillator signal to produce a 455-kHz intermediate frequency (IF) signal?
-
Mixer (81% chose this)
-
BFO (11% chose this)
-
VFO (4% chose this)
-
Multiplier (4% chose this)
What is meant by "back EMF"?
-
A voltage that opposes the applied EMF (57% chose this)
-
A current that opposes the applied EMF (22% chose this)
-
An opposing EMF equal to R times C percent of the applied EMF (16% chose this)
-
A current equal to the applied EMF (6% chose this)
What is the resonant frequency of a parallel RLC circuit if R is 4.7 kilohms, L is 15 microhenrys and C is 5 picofarads?
-
18.4 kHz (7% chose this)
-
18.4 MHz (68% chose this)
-
2.12 kHz (3% chose this)
-
2.12 MHz (22% chose this)
What is the resonant frequency of a parallel RLC circuit if R is 4.7 kilohms, L is 1 microhenry and C is 10 picofarads?
-
50.3 MHz (68% chose this)
-
15.9 kHz (2% chose this)
-
50.3 kHz (3% chose this)
-
15.9 MHz (26% chose this)
The matching of a driven element with a single adjustable mechanical and capacitive arrangement is descriptive of:
-
a "T" match (11% chose this)
-
an "omega" match (4% chose this)
-
a "Y" match (3% chose this)
-
a "gamma" match (82% chose this)
Which type of signal is used to produce a predetermined alteration in the carrier for spread spectrum communication?
-
Frequency-companded sequence (12% chose this)
-
Quantizing noise (7% chose this)
-
Random noise sequence (8% chose this)
-
Pseudo-random sequence (72% chose this)
With a normal load, the choke input filter will give the:
-
highest output voltage (20% chose this)
-
best regulated output (75% chose this)
-
greatest percentage of ripple (3% chose this)
-
greatest ripple frequency (3% chose this)
For single-sideband phone emissions, what would be the bandwidth of a good crystal lattice filter?
-
2.4 kHz (71% chose this)
-
15 kHz (6% chose this)
-
500 Hz (6% chose this)
-
6 kHz (17% chose this)
What are the major ratings for junction diodes?
-
Maximum reverse current and capacitance (2% chose this)
-
Maximum forward current and capacitance (10% chose this)
-
Maximum reverse current and peak inverse voltage (PIV) (15% chose this)
-
Maximum forward current and peak inverse voltage (PIV) (73% chose this)
Compared with coaxial cable, microstripline:
-
must have much higher characteristic impedance (7% chose this)
-
has poorer shielding (82% chose this)
-
has superior shielding (3% chose this)
-
must have much lower characteristic impedance (8% chose this)
Which of the following classes of amplifier provides the highest efficiency?
-
Class B (0% chose this)
-
Class C (73% chose this)
-
Class A (24% chose this)
-
Class AB (2% chose this)
Harmonics produced in an early stage of a transmitter may be reduced in a later stage by:
-
greater input to the final stage (3% chose this)
-
transistors instead of tubes (4% chose this)
-
tuned circuit coupling between stages (85% chose this)
-
larger value coupling capacitors (8% chose this)
When extremely low ripple is required, or when the voltage supplied to the load must remain constant under conditions of large fluctuations of current and line voltage, a closed-loop amplifier is used to regulate the power supply. There are two main categories of electronic regulators. They are:
-
non-linear and switching (4% chose this)
-
linear and non-linear (17% chose this)
-
stiff and switching (0% chose this)
-
linear and switching (79% chose this)
Distortion in a receiver that only affects strong signals usually indicates a defect in or mis-adjustment of the:
-
RF amplifier (8% chose this)
-
automatic gain control (AGC) (79% chose this)
-
IF amplifier (6% chose this)
-
AF amplifier (6% chose this)
What is a non-inverting op-amp circuit?
-
An operational amplifier circuit connected such that the input and output signals are 90 degrees out of phase (2% chose this)
-
An operational amplifier circuit connected such that the input impedance is held low, and the output impedance is high (11% chose this)
-
An operational amplifier circuit connected such that the input and output signals are 180 degrees out of phase (14% chose this)
-
An operational amplifier circuit connected such that the input and output signals are in phase (73% chose this)
In a half-wave dipole, the distribution of _______ is highest at each end.
-
current (23% chose this)
-
inductance (6% chose this)
-
capacitance (1% chose this)
-
voltage (70% chose this)
How can intermodulation interference between two repeater transmitters in close proximity often be reduced or eliminated?
-
By using a Class C final amplifier with high driving power (1% chose this)
-
By installing a terminated circulator or ferrite isolator in the transmission line to the transmitter and duplexer (69% chose this)
-
By installing a low-pass filter in the antenna transmission line (17% chose this)
-
By installing a high-pass filter in the antenna transmission line (13% chose this)
What is the easiest amplitude dimension to measure by viewing a pure sine wave on an oscilloscope?
-
Average voltage (3% chose this)
-
Peak-to-peak voltage (76% chose this)
-
Peak voltage (14% chose this)
-
RMS voltage (8% chose this)
What is a dip meter?
-
A marker generator (3% chose this)
-
A field-strength meter (13% chose this)
-
A variable frequency oscillator with metered feedback current (78% chose this)
-
An SWR meter (6% chose this)
A modern type of regulator, which features a reference, high-gain amplifier, temperature-compensated voltage sensing resistors and transistors as well as a pass element is commonly referred to as a:
-
three-terminal regulator (88% chose this)
-
nine-pin terminal regulator (4% chose this)
-
twenty-four pin terminal (1% chose this)
-
regulator six-terminal regulator (6% chose this)
Which of the following properties does not apply to a crystal when used in an oscillator circuit?
-
Good frequency accuracy (8% chose this)
-
High power output (77% chose this)
-
Good frequency stability (3% chose this)
-
Very low noise because of high Q (13% chose this)
For what portion of a signal cycle does a Class A amplifier operate?
-
The entire cycle (79% chose this)
-
Exactly 180 degrees (8% chose this)
-
More than 180 degrees but less than 360 degrees (6% chose this)
-
Less than 180 degrees (6% chose this)
An apparatus with an oscillator and a class C amplifier would be:
-
a two-stage CW transmitter (73% chose this)
-
a fixed-frequency single-sideband transmitter (13% chose this)
-
a two-stage frequency-modulated transmitter (12% chose this)
-
a two-stage regenerative receiver (2% chose this)
Poor frequency stability in a receiver usually originates in the:
-
mixer (4% chose this)
-
local oscillator and power supply (84% chose this)
-
detector (7% chose this)
-
RF amplifier (5% chose this)
What is the resonant frequency of a parallel RLC circuit if R is 4.7 kilohms, L is 2 microhenrys and C is 30 picofarads?
-
20.5 MHz (79% chose this)
-
2.65 MHz (13% chose this)
-
2.65 kHz (3% chose this)
-
20.5 kHz (5% chose this)
The silicon controlled rectifier (SCR) is what type of device?
-
NPPN (11% chose this)
-
PNNP (16% chose this)
-
PPNN (1% chose this)
-
PNPN (71% chose this)
The designator AX.25 is associated with which amateur radio mode?
-
packet (82% chose this)
-
RTTY (7% chose this)
-
ASCII (4% chose this)
-
spread spectrum speech (8% chose this)
A transmitter has an output power of 200 watts. The coaxial and connector losses are 3 dB in total, and the antenna gain is 9 dBd. What is the approximate Effective Radiated Power of this system?
-
800 watts (75% chose this)
-
3200 watts (1% chose this)
-
1600 watts (8% chose this)
-
400 watts (16% chose this)
Under what operating condition does a silicon controlled rectifier (SCR) exhibit electrical characteristics similar to a forward-biased silicon rectifier?
-
When it is used as a detector (13% chose this)
-
During a switching transition (9% chose this)
-
When it is gated "on" (71% chose this)
-
When it is gated "off" (7% chose this)
The overall output of an AM/CW/SSB receiver can be adjusted by means of manual controls on the receiver or by use of a circuit known as:
-
automatic load control (7% chose this)
-
automatic gain control (83% chose this)
-
automatic frequency control (8% chose this)
-
inverse gain control (3% chose this)
What does a dip meter do?
-
It gives an indication of the resonant frequency of a circuit (81% chose this)
-
It measures transmitter output power accurately (1% chose this)
-
It measures field strength accurately (5% chose this)
-
It measures frequency accurately (13% chose this)
Why is it difficult to monitor a spread spectrum transmission?
-
It varies too quickly in amplitude (12% chose this)
-
The signal is too distorted for comfortable listening (1% chose this)
-
Your receiver must be frequency-synchronized to the transmitter (81% chose this)
-
It requires narrower bandwidth than most receivers have (6% chose this)
In a half-wave dipole, the highest distribution of ________ occurs at the middle.
-
current (75% chose this)
-
inductance (8% chose this)
-
voltage (17% chose this)
-
capacity (0% chose this)
What is a NOR gate?
-
A circuit that produces a logic "1" at its output if some but not all of its inputs are logic "1" (9% chose this)
-
A circuit that produces a logic "0" at its output if any or all inputs are logic "1" (73% chose this)
-
A circuit that produces a logic "0" at its output only if all inputs are logic "0" (9% chose this)
-
A circuit that produces a logic "1" at its output only if all inputs are logic "1" (8% chose this)
What is the term for the reduction in receiver sensitivity caused by a strong signal near the received frequency?
-
Desensitization (88% chose this)
-
Cross-modulation interference (10% chose this)
-
Squelch gain rollback (1% chose this)
-
Quieting (1% chose this)
What is the Q of a parallel RLC circuit, if it is resonant at 14.225 MHz, L is 3.5 microhenrys and R is 10 kilohms?
-
71.5 (13% chose this)
-
31.9 (67% chose this)
-
7.35 (12% chose this)
-
0.0319 (9% chose this)
Electrically, what does a crystal look like?
-
A variable tuned circuit (11% chose this)
-
A very high Q tuned circuit (71% chose this)
-
A very low Q tuned circuit (9% chose this)
-
A variable capacitance (9% chose this)
Why are very low noise figures relatively unimportant for a high frequency receiver?
-
The use of SSB and CW on the HF bands overcomes the noise (7% chose this)
-
Regardless of the front end, the succeeding stages when used on HF are very noisy (3% chose this)
-
External HF noise, man-made and natural, are higher than the internal noise generated by the receiver (84% chose this)
-
Ionospheric distortion of the received signal creates high noise levels (7% chose this)
The impedance of a half-wave antenna at its centre is low, because at this point:
-
voltage and current are both low (4% chose this)
-
voltage is high and current is low (8% chose this)
-
voltage is low and current is high (83% chose this)
-
voltage and current are both high (5% chose this)
What is the resonant frequency of a parallel RLC circuit if R is 4.7 kilohms, L is 5 microhenrys and C is 9 picofarads?
-
3.54 kHz (0% chose this)
-
23.7 MHz (73% chose this)
-
23.7 kHz (5% chose this)
-
3.54 MHz (22% chose this)
Electron conduction in an n-channel enhancement MOSFET is associated with:
-
q-channel depletion (0% chose this)
-
p-channel enhancement (11% chose this)
-
p-channel depletion (19% chose this)
-
n-channel enhancement (70% chose this)
What is the reason for neutralizing the final amplifier stage of a transmitter?
-
To cut off the final amplifier during standby periods (8% chose this)
-
To keep the carrier on frequency (5% chose this)
-
To eliminate parasitic oscillations (86% chose this)
-
To limit the modulation index (0% chose this)
Which of the following is a PNPN device?
-
Zener diode (10% chose this)
-
Silicon controlled rectifier (SCR) (81% chose this)
-
PIN diode (0% chose this)
-
Hot carrier (Schottky) diode (9% chose this)
Resonant cavities are used by amateurs as a:
-
high-pass filter above 30 MHz (9% chose this)
-
narrow bandpass filter at VHF and higher frequencies (74% chose this)
-
power line filter (4% chose this)
-
low-pass filter below 30 MHz (13% chose this)
What is a typical velocity factor for coaxial cable with polyethylene dielectric?
-
0.66 (81% chose this)
-
0.33 (8% chose this)
-
0.1 (5% chose this)
-
2.7 (6% chose this)
How does intermodulation interference between two repeater transmitters usually occur?
-
When they are in close proximity and the signals mix in one or both of their final amplifiers (77% chose this)
-
When the signals are reflected in phase by aircraft passing overhead (1% chose this)
-
When they are in close proximity and the signals cause feedback in one or both of their final amplifiers (20% chose this)
-
When the signals are reflected out of phase by aircraft passing overhead (1% chose this)
A full-wave bridge rectifier circuit makes use of both halves of the AC cycle, but unlike the full-wave centre-tap rectifier circuit it does not require:
-
a centre-tapped secondary on the transformer (76% chose this)
-
any output filtering (4% chose this)
-
a centre-tapped primary on the transformer (12% chose this)
-
diodes across each leg of the transformer (8% chose this)
In a superheterodyne receiver with automatic gain control (AGC), as the strength of the signal increases, the AGC:
-
distorts the signal (4% chose this)
-
introduces limiting (4% chose this)
-
reduces the receiver gain (83% chose this)
-
increases the receiver gain (9% chose this)
The velocity factor of a transmission line is the:
-
speed at which the signal travels in free space (8% chose this)
-
speed to which the standing waves are reflected back to the transmitter (0% chose this)
-
ratio of the velocity of propagation in the transmission line to the velocity of propagation in free space (89% chose this)
-
impedance of the line, e.g. 50 ohm, 75 ohm, etc. (3% chose this)
A quarter-wave stub, for use at 15 MHz, is made from a coaxial cable having a velocity factor of 0.8. Its physical length will be:
-
4 m (13.1 ft) (83% chose this)
-
12 m (39.4 ft) (12% chose this)
-
8 m (26.2 ft) (3% chose this)
-
7.5 m (24.6 ft) (3% chose this)
What factors determine the radiation resistance of an antenna?
-
Sunspot activity and time of day (0% chose this)
-
It is a physical constant and is the same for all antennas (1% chose this)
-
Antenna location with respect to nearby objects and the conductors length/diameter ratio (75% chose this)
-
Transmission line length and antenna height (24% chose this)
What factors limit the accuracy, frequency response and stability of an oscilloscope?
-
Tube face voltage increments and deflection amplifier voltages (4% chose this)
-
Accuracy of the time base and the linearity and bandwidth of the deflection amplifiers (80% chose this)
-
Deflection amplifier output impedance and tube face frequency increments (1% chose this)
-
Accuracy and linearity of the time base and tube face voltage increments (15% chose this)
Why can a horizontal antenna closer to ground be advantageous for close range communications on lower HF bands?
-
The ground tends to act as a reflector (74% chose this)
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Lower antenna noise temperature (1% chose this)
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Low radiation angle for closer distances (19% chose this)
-
The radiation resistance is higher (6% chose this)
In a power supply, series chokes will:
-
impede the passage of DC but will pass the AC component (10% chose this)
-
impede both DC and AC (6% chose this)
-
readily pass the DC but will impede the flow of the AC component (80% chose this)
-
readily pass the DC and the AC component (4% chose this)
What is the primary advantage of the Butterworth filter over the Chebyshev filter?
-
It requires only capacitors (2% chose this)
-
It has maximally flat response over its passband (68% chose this)
-
It allows ripple in the passband in return for steeper skirts (24% chose this)
-
It requires only inductors (5% chose this)
The sensitivity of a voltmeter, whose resistance is 150 000 ohms on the 150-volt range, is:
-
150 ohms per volt (9% chose this)
-
1000 ohms per volt (83% chose this)
-
100 000 ohms per volt (3% chose this)
-
10 000 ohms per volt (5% chose this)
Which component conducts electricity from a positive emitter to a negative collector when its base is made negative?
-
A varactor (3% chose this)
-
An NPN transistor (25% chose this)
-
A PNP transistor (67% chose this)
-
A triode vacuum tube (5% chose this)
What do you call the circuit which employs an analog to digital converter, a mathematical transform, a digital to analog converter and a low pass filter?
-
Digital formatter (0% chose this)
-
Mathematical transformer (6% chose this)
-
Digital transformer (9% chose this)
-
Digital signal processor (84% chose this)
Which of the following is a major advantage of waveguide over coaxial cable for use at microwave frequencies?
-
Very low losses (87% chose this)
-
Frequency response from 1.8 MHz to 24GHz (8% chose this)
-
Easy to install (4% chose this)
-
Inexpensive to install (1% chose this)
When discussing a power supply the_______ resistance is equal to the output voltage divided by the total current drawn, including the current drawn by the bleeder resistor:
-
load (90% chose this)
-
ideal (6% chose this)
-
rectifier (3% chose this)
-
differential (1% chose this)
Why would one need to know the radiation resistance of an antenna?
-
To match impedances for maximum power transfer (76% chose this)
-
To measure the near-field radiation density from a transmitting antenna (14% chose this)
-
To calculate the front-to-side ratio of the antenna (1% chose this)
-
To calculate the front-to-back ratio of the antenna (8% chose this)
How many information bits are included in the ISO-8859 extension to the ASCII code?
-
8 (81% chose this)
-
7 (8% chose this)
-
6 (4% chose this)
-
5 (8% chose this)
A transmitter has a power output of 100 watts. There is a loss of 1.30 dB in the transmission line, a loss of 0.2 dB through the antenna tuner, and a gain of 4.50 dBd in the antenna. The Effective Radiated Power (ERP) is:
-
800 watts (5% chose this)
-
400 watts (8% chose this)
-
100 watts (5% chose this)
-
200 watts (82% chose this)
What is the resonant frequency of a series RLC circuit, if R is 47 ohms, L is 3 microhenrys and C is 40 picofarads?
-
13.1 MHz (15% chose this)
-
13.1 kHz (2% chose this)
-
14.5 kHz (9% chose this)
-
14.5 MHz (74% chose this)
What is a bistable multivibrator?
-
A flip-flop (69% chose this)
-
An OR gate (7% chose this)
-
An AND gate (7% chose this)
-
A clock (16% chose this)
As standing wave ratio rises, so does the loss in the transmission line. This is caused by:
-
high antenna currents (4% chose this)
-
high antenna voltage (5% chose this)
-
leakage to ground through the dielectric (5% chose this)
-
dielectric and conductor heat losses (86% chose this)
A transmitter has an output of 100 watts. The cable and connectors have a composite loss of 3 dB, and the antenna has a gain of 6 dBd. What is the Effective Radiated Power?
-
350 watts (3% chose this)
-
400 watts (6% chose this)
-
300 watts (6% chose this)
-
200 watts (85% chose this)
Which class of amplifier has the highest linearity and least distortion?
-
Class A (80% chose this)
-
Class AB (5% chose this)
-
Class B (1% chose this)
-
Class C (13% chose this)
What are the principal frequencies that appear at the output of a mixer circuit?
-
The original frequencies and the sum and difference frequencies (75% chose this)
-
1.414 and 0.707 times the input frequencies (6% chose this)
-
The sum, difference and square root of the input frequencies (15% chose this)
-
Two and four times the original frequency (5% chose this)
The first mixer in the receiver mixes the incoming signal with the local oscillator to produce:
-
an audio frequency (0% chose this)
-
a radio frequency (9% chose this)
-
a high frequency oscillator (HFO) frequency (4% chose this)
-
an intermediate frequency (87% chose this)
Frequency hopping is used with which type of transmission?
-
Packet (1% chose this)
-
RTTY (3% chose this)
-
Spread spectrum (90% chose this)
-
AMTOR (5% chose this)
What is the principal characteristic of a Zener diode?
-
A negative resistance region (3% chose this)
-
An internal capacitance that varies with the applied voltage (9% chose this)
-
A constant voltage under conditions of varying current (74% chose this)
-
A constant current under conditions of varying voltage (13% chose this)
What is the resonant frequency of a series RLC circuit, if R is 47 ohms, L is 50 microhenrys and C is 10 picofarads?
-
3.18 MHz (23% chose this)
-
3.18 kHz (4% chose this)
-
7.12 MHz (68% chose this)
-
7.12 kHz (5% chose this)
What are the distinguishing features of a Butterworth filter?
-
It only requires conductors (1% chose this)
-
It only requires capacitors (6% chose this)
-
It has a maximally flat response over its pass-band (80% chose this)
-
The product of its series and shunt-element impedances is a constant for all frequencies (12% chose this)
Which class of amplifier has the poorest linearity and the most distortion?
-
Class C (85% chose this)
-
Class AB (5% chose this)
-
Class A (9% chose this)
-
Class B (1% chose this)
Structurally, what are the two main categories of semiconductor diodes?
-
Junction and point contact (78% chose this)
-
Vacuum and point contact (2% chose this)
-
Electrolytic and point contact (7% chose this)
-
Electrolytic and junction (13% chose this)
What occurs when an excessive amount of signal energy reaches the mixer circuit?
-
Mixer blanking occurs (8% chose this)
-
Spurious signals are generated (85% chose this)
-
Automatic limiting occurs (6% chose this)
-
A beat frequency is generated (1% chose this)
In a circuit where the components are tuned to resonate at a higher frequency than applied, the circuit is most likely a:
-
a frequency divider (6% chose this)
-
a frequency multiplier (79% chose this)
-
a VHF/UHF amplifier (8% chose this)
-
a linear amplifier (7% chose this)
Why is the physical length of a coaxial cable shorter than its electrical length?
-
The surge impedance is higher in the parallel transmission line (1% chose this)
-
Skin effect is less pronounced in the coaxial cable (11% chose this)
-
The characteristic impedance is higher in a parallel transmission line (4% chose this)
-
RF energy moves slower along the coaxial cable than in air (84% chose this)
Which of the following is an advantage of waveguide as a transmission line?
-
Heavy and difficult to install (0% chose this)
-
Low loss (89% chose this)
-
Frequency sensitive based on dimensions (9% chose this)
-
Expensive (1% chose this)
What is the term for the ratio of the actual velocity at which a signal travels through a transmission line to the speed of light in a vacuum?
-
Surge impedance (0% chose this)
-
Standing wave ratio (7% chose this)
-
Velocity factor (91% chose this)
-
Characteristic impedance (3% chose this)
What is the resonant frequency of a parallel RLC circuit if R is 4.7 kilohms, L is 2 microhenrys and C is 15 picofarads?
-
29.1 kHz (3% chose this)
-
5.31 MHz (23% chose this)
-
5.31 kHz (2% chose this)
-
29.1 MHz (72% chose this)
What is an OR gate?
-
A circuit that produces logic "1" at its output if all inputs are logic "0" (5% chose this)
-
A circuit that produces a logic "0" at its output if any input is logic "1" (10% chose this)
-
A circuit that produces a logic "1" at its output if any input is logic "1" (80% chose this)
-
A circuit that produces a logic "0" at its output if all inputs are logic "1" (6% chose this)
Electron conduction in an n-channel depletion type MOSFET is associated with:
-
p-channel depletion (7% chose this)
-
p-channel enhancement (16% chose this)
-
q-channel enhancement (1% chose this)
-
n-channel depletion (76% chose this)
Which class of amplifier operates over the full cycle?
-
Class B (4% chose this)
-
Class C (10% chose this)
-
Class A (83% chose this)
-
Class AB (4% chose this)
The frequency accuracy of a frequency counter is determined by:
-
the size of the frequency counter (3% chose this)
-
type of display used in the counter (0% chose this)
-
the number of digits displayed (4% chose this)
-
the characteristics of the internal time-base generator (93% chose this)
What are the distinguishing features of a Chebyshev filter?
-
It has a maximally flat response in the passband (14% chose this)
-
It allows ripple in the passband in return for steeper skirts (80% chose this)
-
It requires only inductors (2% chose this)
-
It requires only capacitors (4% chose this)
What is the resonant frequency of a series RLC circuit, if R is 47 ohms, L is 3 microhenrys and C is 15 picofarads?
-
23.7 kHz (6% chose this)
-
23.7 MHz (81% chose this)
-
35.4 MHz (13% chose this)
-
35.4 kHz (0% chose this)
What causes receiver desensitization?
-
Squelch gain adjusted too high (5% chose this)
-
Squelch gain adjusted too low (4% chose this)
-
Audio gain adjusted too low (1% chose this)
-
Strong near frequency signals (89% chose this)
In what application is gallium-arsenide used as a semiconductor material in preference to germanium or silicon?
-
In bipolar transistors (10% chose this)
-
At microwave frequencies (78% chose this)
-
In high-power circuits (7% chose this)
-
At very low frequencies (5% chose this)
In a regulated power supply, four diodes connected together in a BRIDGE act as:
-
matching between the secondary of the power transformer and the filter (5% chose this)
-
a tuning network (5% chose this)
-
a rectifier (88% chose this)
-
equalization across the transformer (1% chose this)
What is the resonant frequency of a series RLC circuit, if R is 47 ohms, L is 1 microhenry and C is 9 picofarads?
-
53.1 MHz (71% chose this)
-
5.31 MHz (12% chose this)
-
17.7 MHz (9% chose this)
-
1.77 MHz (8% chose this)
Stripline is a:
-
family of fluids for removing coatings from small parts (1% chose this)
-
printed circuit transmission line (85% chose this)
-
small semiconductor family (9% chose this)
-
high power microwave antenna (5% chose this)
Hole conduction in a p-channel depletion type MOSFET is associated with:
-
p-channel depletion (78% chose this)
-
n-channel enhancement (10% chose this)
-
q-channel depletion (1% chose this)
-
n-channel depletion (10% chose this)
What is a three-terminal regulator?
-
A regulator containing three error amplifiers and sensing transistors (3% chose this)
-
A regulator that supplies three voltages with variable current (4% chose this)
-
A regulator containing a voltage reference, error amplifier, sensing resistors and transistors, and a pass element (87% chose this)
-
A regulator that supplies three voltages at a constant current (6% chose this)
What is the resonant frequency of a series RLC circuit, if R is 47 ohms, L is 4 microhenrys and C is 8 picofarads?
-
28.1 MHz (80% chose this)
-
49.7 MHz (12% chose this)
-
49.7 kHz (4% chose this)
-
28.1 kHz (5% chose this)
After you have opened a VHF power amplifier to make internal tuning adjustments, what should you do before you turn the amplifier on?
-
Remove all amplifier shielding to ensure maximum cooling (1% chose this)
-
Be certain all amplifier shielding is fastened in place (86% chose this)
-
Make sure that the power interlock switch is bypassed so you can test the amplifier (5% chose this)
-
Be certain no antenna is attached so that you will not cause any interference (8% chose this)
What are the three terminals of a junction field-effect transistor (JFET)?
-
Gate 1, gate 2, drain (3% chose this)
-
Gate, drain, source (78% chose this)
-
Emitter, base 1, base 2 (1% chose this)
-
Emitter, base, collector (17% chose this)
What is an inverting op-amp circuit?
-
An operational amplifier circuit connected such that the input impedance is held to zero, while the output impedance is high (8% chose this)
-
An operational amplifier circuit connected such that the input and output signals are 180 degrees out of phase (77% chose this)
-
An operational amplifier circuit connected such that the input and output signals are in phase (8% chose this)
-
An operational amplifier circuit connected such that the input and output signals are 90 degrees out of phase (7% chose this)
Greater distance can be covered with multiple-hop transmissions by decreasing the:
-
power applied to the antenna (3% chose this)
-
main height of the antenna (8% chose this)
-
length of the antenna (3% chose this)
-
vertical radiation angle of the antenna (87% chose this)
How does antenna height affect the horizontal (azimuthal) radiation pattern of a horizontal dipole HF antenna?
-
If the antenna is less than one-half wavelength high, reflected radio waves from the ground significantly distort the pattern (88% chose this)
-
Antenna height has no effect on the pattern (3% chose this)
-
If the antenna is less than one-half wavelength high, radiation off the ends of the wire is eliminated (6% chose this)
-
If the antenna is too high, the pattern becomes unpredictable (3% chose this)
The clock in a frequency counter normally uses a:
-
crystal oscillator (90% chose this)
-
self-oscillating Hartley oscillator (4% chose this)
-
mechanical tuning fork (0% chose this)
-
free-running multivibrator (6% chose this)
The power supplied to the antenna transmission line by a transmitter during an RF cycle at the highest crest of the modulation envelope is known as:
-
mean power (0% chose this)
-
carrier power (1% chose this)
-
full power (5% chose this)
-
peak-envelope power (93% chose this)
What device is typically used as a stable reference voltage in a linear voltage regulator?
-
A varactor diode (2% chose this)
-
A junction diode (4% chose this)
-
A Zener diode (86% chose this)
-
An SCR (7% chose this)
Which type of filter would be best to use in a 2-metre repeater duplexer?
-
A DSP filter (10% chose this)
-
An L-C filter (6% chose this)
-
A crystal filter (9% chose this)
-
A cavity filter (75% chose this)
What term is most appropriate for a high gain, direct-coupled differential amplifier whose characteristics are determined by components mounted externally?
-
Summing amplifier (2% chose this)
-
Operational amplifier (83% chose this)
-
Difference amplifier (4% chose this)
-
High gain audio amplifier (11% chose this)
What type of digital logic is also known as a latch?
-
A decade counter (2% chose this)
-
An OR gate (19% chose this)
-
An op-amp (4% chose this)
-
A flip-flop (74% chose this)
A parabolic antenna is very efficient because:
-
a horn-type radiator can be used to trap the received energy (8% chose this)
-
all the received energy is focused to a point where the pick-up antenna is located (84% chose this)
-
a dipole antenna can be used to pick up the received energy (1% chose this)
-
no impedance matching is required (6% chose this)
What are the three general groupings of filters?
-
Hartley, Colpitts and Pierce (10% chose this)
-
Audio, radio and capacitive (0% chose this)
-
Inductive, capacitive and resistive (8% chose this)
-
High-pass, low-pass and band-pass (81% chose this)
What is an AND gate?
-
A circuit that produces a logic "1" at its output only if one of its inputs is logic "1" (6% chose this)
-
A circuit that produces a logic "1" at its output if all inputs are logic "0" (4% chose this)
-
A circuit that produces a logic "1" at its output only if all its inputs are logic "1" (89% chose this)
-
A circuit that produces a logic "1" at the output if at least one input is a logic "0" (1% chose this)
At what line impedance do most RF wattmeters usually operate?
-
25 ohms (1% chose this)
-
100 ohms (4% chose this)
-
300 ohms (5% chose this)
-
50 ohms (90% chose this)
What is frequency hopping spread spectrum?
-
The carrier is frequency-companded (1% chose this)
-
The carrier is phase-shifted by a fast binary bit stream (7% chose this)
-
The carrier frequency is changed in accordance with a pseudo-random list of channels (87% chose this)
-
The carrier is amplitude-modulated over a wide range called the spread (5% chose this)
The main advantage of a crystal oscillator over a tuned LC oscillator is:
-
freedom from harmonic emissions (5% chose this)
-
simplicity (7% chose this)
-
much greater frequency stability (88% chose this)
-
longer life under severe operating use (0% chose this)
What is the resonant frequency of a series RLC circuit, if R is 47 ohms, L is 40 microhenrys and C is 200 picofarads?
-
1.99 kHz (5% chose this)
-
1.99 MHz (11% chose this)
-
1.78 kHz (8% chose this)
-
1.78 MHz (75% chose this)
What is the time constant of a circuit having a 470 microfarad capacitor in series with a 470 kilohm resistor?
-
47 000 seconds (4% chose this)
-
470 seconds (20% chose this)
-
221 seconds (70% chose this)
-
221 000 seconds (6% chose this)
What is the resonant frequency of a series RLC circuit, if R is 47 ohms, L is 4 microhenrys and C is 20 picofarads?
-
19.9 MHz (16% chose this)
-
19.9 kHz (2% chose this)
-
17.8 kHz (4% chose this)
-
17.8 MHz (77% chose this)
The control element in the silicon controlled rectifier (SCR) is called the:
-
emitter (6% chose this)
-
gate (83% chose this)
-
anode (6% chose this)
-
cathode (6% chose this)
The power-handling capability of most Zener diodes is rated at 25 degrees C or approximately room temperature. If the temperature is increased, the power handling capability is:
-
much greater (5% chose this)
-
slightly greater (9% chose this)
-
less (80% chose this)
-
the same (5% chose this)
After two time constants, the capacitor in an RC circuit is charged to what percentage of the supply voltage?
-
86.5% (72% chose this)
-
63.2% (14% chose this)
-
95% (6% chose this)
-
36.8% (9% chose this)
What is the resonant frequency of a parallel RLC circuit if R is 4.7 kilohms, L is 40 microhenrys and C is 6 picofarads?
-
6.63 MHz (16% chose this)
-
6.63 kHz (3% chose this)
-
10.3 kHz (1% chose this)
-
10.3 MHz (79% chose this)
Silicon, in its pure form, is:
-
an insulator (77% chose this)
-
a superconductor (1% chose this)
-
a semiconductor (19% chose this)
-
a conductor (3% chose this)
Between the charged plates of a capacitor there is:
-
an electrostatic field (72% chose this)
-
a magnetic field (16% chose this)
-
a cloud of electrons (9% chose this)
-
an electric current (4% chose this)
What is the primary advantage of the Chebyshev filter over the Butterworth filter?
-
It requires only inductors (2% chose this)
-
It has maximally flat response over the passband (17% chose this)
-
It allows ripple in the passband in return for steeper skirts (78% chose this)
-
It requires only capacitors (3% chose this)
What is the resonant frequency of a parallel RLC circuit if R is 4.7 kilohms, L is 3 microhenrys and C is 40 picofarads?
-
1.33 kHz (3% chose this)
-
1.33 MHz (13% chose this)
-
14.5 kHz (3% chose this)
-
14.5 MHz (81% chose this)
What precautions should you take before beginning repairs on a microwave feed horn or waveguide?
-
Be sure propagation conditions are unfavourable for tropospheric ducting (0% chose this)
-
Be sure to wear tight-fitting clothes and gloves to protect your body and hands from sharp edges (0% chose this)
-
Be sure the transmitter is turned off and the power source is disconnected (100% chose this)
-
Be sure the weather is dry and sunny (0% chose this)
Substances such as silicon in a pure state are usually good:
-
conductors (9% chose this)
-
tuned circuits (0% chose this)
-
inductors (5% chose this)
-
insulators (86% chose this)
In what direction is the magnetic field oriented about a conductor in relation to the direction of electron flow?
-
In the same direction as the current (8% chose this)
-
In the direct opposite to the current (10% chose this)
-
In the direction determined by the left-hand rule (77% chose this)
-
In all directions (5% chose this)
What are the advantages of using an op-amp instead of LC elements in an audio filter?
-
Op-amps are more rugged and can withstand more abuse than can LC elements (9% chose this)
-
Op-amps are available in more styles and types than are LC elements (1% chose this)
-
Op-amps are fixed at one frequency (3% chose this)
-
Op-amps exhibit gain rather than insertion loss (86% chose this)
What is the mixing process?
-
The recovery of intelligence from a modulated signal (6% chose this)
-
The elimination of noise in a wideband receiver by phase comparison (2% chose this)
-
The combination of two signals to produce sum and difference frequencies (92% chose this)
-
The elimination of noise in a wideband receiver by phase differentiation (0% chose this)
If the overall gain of an amateur station is increased by 3 dB the ERP (Effective Radiated Power) will:
-
be cut in half (2% chose this)
-
double (95% chose this)
-
decrease by 3 watts (1% chose this)
-
remain the same (1% chose this)
A semiconductor is said to be doped when it has added to it small quantities of:
-
ions (6% chose this)
-
electrons (11% chose this)
-
impurities (82% chose this)
-
protons (1% chose this)
If the signals of two repeater transmitters mix together in one or both of their final amplifiers and unwanted signals at the sum and difference frequencies of the original signals are generated and radiated, what is this called?
-
Amplifier desensitization (4% chose this)
-
Intermodulation interference (87% chose this)
-
Neutralization (1% chose this)
-
Adjacent channel interference (8% chose this)
What two elements widely used in semiconductor devices exhibit both metallic and non-metallic characteristics?
-
Galena and germanium (6% chose this)
-
Galena and bismuth (2% chose this)
-
Silicon and gold (1% chose this)
-
Silicon and germanium (91% chose this)
Crystal oscillators, filters and microphones depend upon which principle?
-
Hertzberg effect (5% chose this)
-
Ferro-resonance (4% chose this)
-
Overtone effect (4% chose this)
-
Piezoelectric effect (86% chose this)
A quartz crystal filter is superior to an LC filter for narrow bandpass applications because of the:
-
LC circuit's high Q (2% chose this)
-
crystal's simplicity (3% chose this)
-
crystal's high Q (85% chose this)
-
crystal's low Q (10% chose this)
Energy is stored within an inductor that is carrying a current. The amount of energy depends on this current, but it also depends on a property of the inductor. This property has the following unit:
-
watt (2% chose this)
-
henry (77% chose this)
-
coulomb (8% chose this)
-
farad (14% chose this)
What is the time constant of a circuit having a 220 microfarad capacitor in series with a 470 kilohm resistor?
-
470 seconds (6% chose this)
-
220 seconds (14% chose this)
-
103 seconds (79% chose this)
-
470 000 seconds (1% chose this)
A Zener diode is a device used to:
-
dissipate voltage (2% chose this)
-
decrease current (0% chose this)
-
increase current (1% chose this)
-
regulate voltage (96% chose this)
If a Zener diode rated at 10 V and 50 watts was operated at maximum dissipation rating, it would conduct ____ amperes:
-
50 (4% chose this)
-
0.05 (1% chose this)
-
0.5 (6% chose this)
-
5 (89% chose this)
What is a flip-flop circuit?
-
A binary sequential logic element with one stable state (6% chose this)
-
A binary sequential logic element with two stable states (92% chose this)
-
A binary sequential logic element with eight stable states (1% chose this)
-
A binary sequential logic element with four stable states (1% chose this)
Filter chokes are rated according to:
-
power loss (2% chose this)
-
breakdown voltage (1% chose this)
-
inductance and current-handling capacity (93% chose this)
-
reactance at 1000 Hz (4% chose this)
What is a NOT gate (also known as an INVERTER)?
-
A circuit that produces a logic "0" at its output when the input is logic "1" (90% chose this)
-
A circuit that does not allow data transmission when its input is high (2% chose this)
-
A circuit that allows data transmission only when its input is high (2% chose this)
-
A circuit that produces a logic "1" at its output when the input is logic "1" (6% chose this)
Why are special precautions necessary in handling FET and CMOS devices?
-
They are light-sensitive (2% chose this)
-
They have micro-welded semiconductor junctions that are susceptible to breakage (8% chose this)
-
They have fragile leads that may break off (3% chose this)
-
They are susceptible to damage from static charges (87% chose this)
Which AC voltage value will produce the same amount of heat as a DC voltage, when applied to the same resistance?
-
The average value (3% chose this)
-
The peak value (0% chose this)
-
The peak-to-peak value (3% chose this)
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The RMS value (93% chose this)
What is the term for energy that is stored in an electromagnetic or electrostatic field?
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Potential energy (80% chose this)
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Kinetic energy (6% chose this)
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Ampere-joules (5% chose this)
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Joule-coulombs (10% chose this)
What is the result of skin effect?
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Thermal effects on the surface of the conductor increase impedance (5% chose this)
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Thermal effects on the surface of the conductor decrease impedance (4% chose this)
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As frequency increases, RF current flows in a thinner layer of the conductor, closer to the surface (86% chose this)
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As frequency decreases, RF current flows in a thinner layer of the conductor, closer to the surface (4% chose this)
What unit measures the ability of a capacitor to store electrical charge?
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Coulomb (13% chose this)
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Watt (1% chose this)
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Volt (2% chose this)
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Farad (84% chose this)
Which of the following materials is used to make a semiconductor?
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Sulphur (0% chose this)
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Silicon (99% chose this)
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Tantalum (0% chose this)
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Copper (1% chose this)
Where does almost all RF current flow in a conductor?
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In a magnetic field in the centre of the conductor (4% chose this)
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In a magnetic field around the conductor (7% chose this)
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In the centre of the conductor (4% chose this)
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Along the surface of the conductor (85% chose this)
An element which is sometimes an insulator and sometimes a conductor is called a:
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P-type conductor (1% chose this)
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semiconductor (95% chose this)
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intrinsic conductor (3% chose this)
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N-type conductor (1% chose this)
What is the term for the time required for the current in an RL circuit to build up to 63.2% of the maximum value?
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One time constant (83% chose this)
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An exponential period of one (4% chose this)
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A time factor of one (11% chose this)
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One exponential rate (2% chose this)
Why is the resistance of a conductor different for RF currents than for direct currents?
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Because of the Hertzberg effect (4% chose this)
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Because conductors are non-linear devices (8% chose this)
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Because the insulation conducts current at high frequencies (4% chose this)
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Because of skin effect (84% chose this)
What is the term for the time required for the capacitor in an RC circuit to be charged to 63.2% of the supply voltage?
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An exponential rate of one (2% chose this)
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A time factor of one (7% chose this)
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One exponential period (3% chose this)
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One time constant (88% chose this)
What is the term for the time it takes for a charged capacitor in an RC circuit to discharge to 36.8% of its initial value of stored charge?
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One time constant (80% chose this)
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A discharge factor of one (5% chose this)
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An exponential discharge of one (3% chose this)
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One discharge period (13% chose this)
Why does most of an RF current flow within a very thin layer under the conductor's surface?
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Because of heating of the conductor's interior (1% chose this)
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Because of skin effect (93% chose this)
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Because the RF resistance of a conductor is much less than the DC resistance (4% chose this)
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Because a conductor has AC resistance due to self-inductance (2% chose this)
A wire has a current passing through it. Surrounding this wire there is:
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an electromagnetic field (92% chose this)
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an electrostatic field (2% chose this)
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a cloud of electrons (0% chose this)
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a skin effect that diminishes with distance (6% chose this)
What effect causes most of an RF current to flow along the surface of a conductor?
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Resonance effect (2% chose this)
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Layer effect (0% chose this)
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Skin effect (97% chose this)
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Piezoelectric effect (1% chose this)
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