Tech Arsenal 1/Tech Arsenal (Arsenal Computer).ISO/tek-20/gen21.zip/GEN4.DAT

Text File | 1991-11-22 | 11KB | 280 lines

096C-6.2   B 3-10  Backscatter signals are usually|quite weak and have a wavering |sound
What is a characteristic of backscatter signals?
A. High intelligibility
B. A wavering sound
C. Reversed modulation
D. Reversed sidebands
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097C-6.4   D 3-10  A small part of the signal is returned|to the skip zone in a random manner so|the backscatter signal is distorted
What makes backscatter signals often sound distorted?
A. Auroral activity and changes in the earth's magnetic field
B. The propagation through ground waves that absorb much of
   the signal's clarity
C. The earth's E-layer at the point of radio wave refraction
D. The small part of the signal's energy scattered back to the
   transmitter skip zone through several radio-wave paths
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098C-6.5   B 3-9   Scatter mode communications|like backscatter
What is the radio wave propagation phenomenon that allows a
signal to be detected at a distance too far for ground wave
propagation but too near for normal sky wave propagation?
A. Ground wave
B. Scatter
C. Sporadic-E skip
D. Short path skip
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099C-6.6   D 3-9   At frequencies above MUF
When does ionospheric scatter propagation on the HF
bands most often occur?
A. When the sunspot cycle is at a minimum
B. At night
C. When the F1 and F2 layers are combined
D. At frequencies above the maximum usable frequency
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100C-7.1   B 3-6   Radio energy from sun
What is solar flux?
A. The density of the sun's magnetic field
B. The radio energy emitted by the sun
C. The number of sunspots on the side of the sun facing
   the earth
D. A measure of the tilt of the earth's ionosphere on the
   side toward the sun
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101C-7.2   D 3-6   The solar flux index is a daily|measurement of the energy from |the sun measured at 2800 MHz
What is the solar-flux index?
A. A measure of past measurements of solar activity
B. A measurement of solar activity that compares daily readings
   with results from the last six months
C. Another name for the American sunspot number
D. A measure of solar activity that is taken daily
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102C-7.3   A 3-6   The solar flux index is a daily|measurement of the energy from |the sun measured at 2800 MHz
What is a timely indicator of solar activity?
A. The 2800-MHz solar flux index
B. The mean Canadian sunspot number
C. A clock set to Coordinated Universal Time
D. Van Allen radiation measurements taken at Boulder,
   Colorado
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103C-7.4   D 3-6   A solar-flux index value less than 80 |indicates poor conditions on 15 meters|and above 80 indicates good conditions
What type of propagation conditions on the 15-meter wavelength
band are indicated by a solar-flux index value of 60 to 70?
A. Unpredictable ionospheric propagation
B. No ionospheric propagation is possible
C. Excellent ionospheric propagation
D. Poor ionospheric propagation
*
104C-7.5   D 3-6   A solar-flux index value less than 80 |indicates poor conditions on 15 meters|and above 80 indicates good conditions
A solar flux index in the range of 90 to 110 indicates what type
of propagation conditions on the 15-meter wavelength band?
A. Poor ionospheric propagation
B. No ionospheric propagation is possible
C. Unpredictable ionospheric propagation
D. Good ionospheric propagation
*
105C-7.6   A 3-6   A solar-flux index value greater than:|120 indicates good conditions on 10|250 indicates good conditions on 6
A solar flux index of greater than 120 would indicate what type
of propagation conditions on the 10-meter wavelength band?
A. Good ionospheric propagation
B. Poor ionospheric propagation
C. No ionospheric propagation is possible
D. Unpredictable ionospheric propagation
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106C-7.7   D 3-6   A solar-flux index value greater than:|120 indicates good conditions on 10|250 indicates good conditions on 6
For widespread long distance openings on the 6-meter wavelength
band, what solar-flux index values would be required?
A. Less than 50
B. Approximately 75
C. Greater than 100
D. Greater than 250
*
107C-7.8   C 3-6   27 Days
If the MUF is high and HF radio communications are generally
good for several days, a similar condition can usually be
expected how many days later?
A. 7 days
B. 14 days
C. 28 days
D. 90 days
*
108C-10.1  D 3-8   Variation in earth's magnetic field
What is a geomagnetic disturbance?
A. A sudden drop in the solar-flux index
B. A shifting of the earth's magnetic pole
C. Ripples in the ionosphere
D. A dramatic change in the earth's magnetic field over a
   short period of time
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109C-10.2  A 3-8   Near poles ie. greater than 45°
Which latitude paths are more susceptible to geomagnetic
disturbances?
A. Those greater than 45 degrees latitude
B. Those less than 45 degrees latitude
C. Equatorial paths
D. All paths are affected equally
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110C-10.3  B 3-8   Degraded communications
What can be the effect of a major geomagnetic storm on radio
communications?
A. Improved high-latitude HF communications
B. Degraded high-latitude HF communications
C. Improved ground-wave propagation
D. Improved chances of ducting at UHF
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111C-10.4  D 3-8   About a day
How long does it take a solar disturbance that increases
the sun's radiation of charged particles to affect radio
wave propagation on earth?
A. The effect is instantaneous
B. 1.5 seconds
C. 8 minutes
D. 20 to 40 hours
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112D-1.5   A 4-2   The hot wires
Which wires in a four conductor line cord should be attached
to fuses in a 234-VAC primary (single phase) power supply?
A. Only the "hot" (black and red) wires
B. Only the "neutral" (white) wire
C. Only the ground (bare) wire
D. All wires
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113D-1.6   A 4-4   # 14
What size wire is normally used on a 15-ampere, 117-VAC
household lighting circuit?
A. AWG number 14
B. AWG number 16
C. AWG number 18
D. AWG number 22
*
114D-1.7   D 4-4   # 12
What size wire is normally used on a 20-ampere, 117-VAC
household appliance circuit?
A. AWG number 20
B. AWG number 16
C. AWG number 14
D. AWG number 12
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115D-1.8   C 4-2   A drop in the line voltage,  possibly |caused by too small a wire size to the|room with the transmitter
What could be a cause of the room lights dimming when the
transmitter is keyed?
A. RF in the AC pole transformer
B. High resistance in the key contacts
C. A drop in AC line voltage
D. The line cord is wired incorrectly
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116D-1.9   D 4-4   Twenty amps.
What size fuse should be used on a #12 wire household
appliance circuit?
A. Maximum of 100 amperes
B. Maximum of 60 amperes
C. Maximum of 30 amperes
D. Maximum of 20 amperes
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117D-2.4   B 4-6   Discharges capacitors when the power|supply is turned off
What safety feature is provided by a bleeder resistor
in a power supply?
A. It improves voltage regulation
B. It discharges the filter capacitors
C. It removes shock hazards from the induction coils
D. It eliminates ground-loop current
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118D-3.1   C 4-9   A two-tone test uses two sine waves|in the transmitter audio passband  |that are not harmonically related
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?
A. Normal speech
B. An audio-frequency sine wave
C. Two audio-frequency sine waves
D. An audio-frequency square wave
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119D-3.2   C 4-9   A two-tone test uses two sine waves|in the transmitter audio passband  |that are not harmonically related
To test the amplitude linearity of a single-sideband
phone transmitter with an oscilloscope, what should
the audio input to the transmitter be?
A. Normal speech
B. An audio-frequency sine wave
C. Two audio-frequency sine waves
D. An audio-frequency square wave
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120D-3.3   C 4-9   A two-tone test uses two audio tones |that are not harmonically related and|output is observed on an oscilloscope
How are two tones used to test the amplitude linearity of a single-
sideband phone transmitter?
A. Two harmonically related audio tones are fed into the micro-
   phone input of the transmitter, and the output is observed on
   an oscilloscope
B. Two harmonically related audio tones are fed into the micro-
   phone input of the transmitter, and the output is observed on
   a distortion analyzer
C. Two non-harmonically related audio tones are fed into the
   microphone input of the transmitter, and the output is observed
   on an oscilloscope
D. Two non-harmonically related audio tones are fed into the
   microphone input of the transmitter, and the output is observed
   on a wattmeter
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121D-3.4   D 4-9   A two-tone test uses two sine waves|in the transmitter audio passband  |that are not harmonically related
What audio frequencies are used in a two-tone test of the linearity
of a single-sideband phone transmitter?
A. 20 Hz and 20,000 Hz tones must be used
B. 1200 Hz and 2400 Hz tones must be used
C. Any two audio tones may be used, but they must be within the
   transmitter audio passband, and must be harmonically related
D. Any two audio tones may be used, but they must be within the
   transmitter audio passband, and should not be harmonically
   related
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122D-3.5   D 4-8   Linearity
What can be determined by making a two-tone test using an
oscilloscope?
A. The percent of frequency modulation
B. The percent of carrier phase shift
C. The frequency deviation
D. The amplifier linearity
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123D-4.1   A 4-11  Adjust the neutralizing circuit for a|minimum change in grid current when  |the output tuning circuit is changed
How can the grid-current meter in a power amplifier be used as a
neutralizing indicator?
A. Tune for minimum change in grid current as the output circuit
   is changed
B. Tune for maximum change in grid current as the output circuit
   is changed
C. Tune for minimum grid current
D. Tune for maximum grid current
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124D-4.2   D 4-10  Prevent oscillation caused by|interelectrode capacitance
Why is neutralization in some vacuum tube amplifiers necessary?
A. To reduce the limits of loaded Q in practical tuned circuits
B. To reduce grid to cathode leakage
C. To cancel acid build-up caused by thorium oxide gas
D. To cancel oscillation caused by the effects of interelectrode
   capacitance
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125D-4.3   C 4-10  Out-of-phase(180°) energy is fed back|to the input of an amplifier from the|output of the amplifier
How is neutralization of an RF amplifier accomplished?
A. By supplying energy from the amplifier output to the
   input on alternate half cycles
B. By supplying energy from the amplifier output to the
   input shifted 360 degrees out of phase
C. By supplying energy from the amplifier output to the
   input shifted 180 degrees out of phase
D. By supplying energy from the amplifier output to the
   input with a proper DC bias
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126D-4.4   B 4-10  Prevents oscillation by|nulling positive feedback
What purpose does a neutralizing circuit serve in an RF
amplifier?
A. It controls differential gain
B. It cancels the effects of positive feedback
C. It eliminates circulating currents
D. It reduces incidental grid modulation
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127D-4.5   B 4-10  To prevent oscillation
What is the reason for neutralizing the final amplifier
stage of a transmitter?
A. To limit the modulation index
B. To eliminate parasitic oscillations
C. To cut off the final amplifier during standby periods
D. To keep the carrier on frequency
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