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Technician Class > SUBELEMENT T0 > Flashcards

SUBELEMENT T0 Flashcards

- 35 terms · AC power circuits, antenna installation, RF hazards [3 Exam Questions - 3 Groups]

1
Q

T0A01 Which is a commonly accepted value for the lowest voltage that can cause a dangerous electric shock?

A. 12 volts

B. 30 volts

C. 120 volts

D. 300 volts

A

B. 30 volts

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2
Q

T0A02 How does current flowing through the body cause a health hazard?

A. By heating tissue

B. It disrupts the electrical functions of cells

C. It causes involuntary muscle contractions

D. All of these choices are correct

A

D. All of these choices are correct

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3
Q

T0A03 What is connected to the green wire in a three-wire electrical AC plug?

A. Neutral

B. Hot

C. Safety ground

D. The white wire

A

C. Safety ground

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4
Q

T0A04 What is the purpose of a fuse in an electrical circuit?

A. To prevent power supply ripple from damaging a circuit

B. To interrupt power in case of overload

C. To limit current to prevent shocks

D. All of these choices are correct

A

B. To interrupt power in case of overload

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5
Q

T0A05 Why is it unwise to install a 20-ampere fuse in the place of a 5-ampere fuse?

A. The larger fuse would be likely to blow because it is rated for higher current

B. The power supply ripple would greatly increase

C. Excessive current could cause a fire

D. All of these choices are correct

A

C. Excessive current could cause a fire

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6
Q

T0A06 What is a good way to guard against electrical shock at your station?

A. Use three-wire cords and plugs for all AC powered equipment

B. Connect all AC powered station equipment to a common safety ground

C. Use a circuit protected by a ground-fault interrupter

D. All of these choices are correct

A

D. All of these choices are correct

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7
Q

T0A07 Which of these precautions should be taken when installing devices for lightning protection in a coaxial cable feedline?

A. Include a parallel bypass switch for each protector so that it can be switched out of the circuit when running high power

B. Include a series switch in the ground line of each protector to prevent RF overload from inadvertently damaging the protector

C. Keep the ground wires from each protector separate and connected to station ground

D. Ground all of the protectors to a common plate which is in turn connected to an external ground

A

D. Ground all of the protectors to a common plate which is in turn connected to an external ground

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8
Q

T0A08 What is one way to recharge a 12-volt lead-acid station battery if the commercial power is out?

A. Cool the battery in ice for several hours

B. Add acid to the battery

C. Connect the battery to a car’s battery and run the engine

D. All of these choices are correct

A

C. Connect the battery to a car’s battery and run the engine

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9
Q

T0A09 What kind of hazard is presented by a conventional 12-volt storage battery?

A. It emits ozone which can be harmful to the atmosphere

B. Shock hazard due to high voltage

C. Explosive gas can collect if not properly vented

D. All of these choices are correct

A

C. Explosive gas can collect if not properly vented

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10
Q

T0A10 What can happen if a lead-acid storage battery is charged or discharged too quickly?

A. The battery could overheat and give off flammable gas or explode

B. The voltage can become reversed

C. The ?memory effect? will reduce the capacity of the battery

D. All of these choices are correct

A

A. The battery could overheat and give off flammable gas or explode

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11
Q

T0A11 Which of the following is good practice when installing ground wires on a tower for lightning protection?

A. Put a loop in the ground connection to prevent water damage to the ground system

B. Make sure that all bends in the ground wires are clean, right angle bends

C. Ensure that connections are short and direct

D. All of these choices are correct

A

C. Ensure that connections are short and direct

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12
Q

T0A12 What kind of hazard might exist in a power supply when it is turned off and disconnected?

A. Static electricity could damage the grounding system

B. Circulating currents inside the transformer might cause damage

C. The fuse might blow if you remove the cover

D. You might receive an electric shock from stored charge in large capacitors

A

D. You might receive an electric shock from stored charge in large capacitors

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13
Q

D. A capacitor across the AC power source”

A

A. A fuse or circuit breaker in series with the AC “hot” conductor

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14
Q

T0B01 When should members of a tower work team wear a hard hat and safety glasses? A. At all times except when climbing the tower B. At all times except when belted firmly to the tower C. At all times when any work is being done on the tower D. Only when the tower exceeds 30 feet in height

A

C. At all times when any work is being done on the tower

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15
Q

T0B02 What is a good precaution to observe before climbing an antenna tower? A. Make sure that you wear a grounded wrist strap B. Remove all tower grounding connections C. Put on a climbing harness and safety glasses D. All of the these choices are correct

A

C. Put on a climbing harness and safety glasses

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16
Q

T0B03 Under what circumstances is it safe to climb a tower without a helper or observer? A. When no electrical work is being performed B. When no mechanical work is being performed C. When the work being done is not more than 20 feet above the ground D. Never

A

D. Never

17
Q

T0B04 Which of the following is an important safety precaution to observe when putting up an antenna tower? A. Wear a ground strap connected to your wrist at all times B. Insulate the base of the tower to avoid lightning strikes C. Look for and stay clear of any overhead electrical wires D. All of these choices are correct

A

C. Look for and stay clear of any overhead electrical wires

18
Q

T0B05 What is the purpose of a gin pole? A. To temporarily replace guy wires B. To be used in place of a safety harness C. To lift tower sections or antennas D. To provide a temporary ground

A

C. To lift tower sections or antennas

19
Q

T0B06 What is the minimum safe distance from a power line to allow when installing an antenna? A. Half the width of your property B. The height of the power line above ground C. 1/2 wavelength at the operating frequency D. So that if the antenna falls unexpectedly, no part of it can come closer than 10 feet to the power wires

A

D. So that if the antenna falls unexpectedly, no part of it can come closer than 10 feet to the power wires

20
Q

T0B07 Which of the following is an important safety rule to remember when using a crank-up tower? A. This type of tower must never be painted B. This type of tower must never be grounded C. This type of tower must never be climbed unless it is in the fully retracted position D. All of these choices are correct

A

C. This type of tower must never be climbed unless it is in the fully retracted position

21
Q

T0B08 What is considered to be a proper grounding method for a tower? A. A single four-foot ground rod, driven into the ground no more than 12 inches from the base B. A ferrite-core RF choke connected between the tower and ground C. Separate eight-foot long ground rods for each tower leg, bonded to the tower and each other D. A connection between the tower base and a cold water pipe

A

C. Separate eight-foot long ground rods for each tower leg, bonded to the tower and each other

22
Q

T0B09 Why should you avoid attaching an antenna to a utility pole? A. The antenna will not work properly because of induced voltages B. The utility company will charge you an extra monthly fee C. The antenna could contact high-voltage power wires D. All of these choices are correct

A

C. The antenna could contact high-voltage power wires

23
Q

T0B10 Which of the following is true concerning grounding conductors used for lightning protection? A. Only non-insulated wire must be used B. Wires must be carefully routed with precise right-angle bends C. Sharp bends must be avoided D. Common grounds must be avoided

A

C. Sharp bends must be avoided

24
Q

T0B11 Which of the following establishes grounding requirements for an amateur radio tower or antenna? A. FCC Part 97 Rules B. Local electrical codes C. FAA tower lighting regulations D. Underwriters Laboratories’ recommended practices

A

B. Local electrical codes

25
Q

T0C01 What type of radiation are VHF and UHF radio signals? A. Gamma radiation B. Ionizing radiation C. Alpha radiation D. Non-ionizing radiation

A

D. Non-ionizing radiation

26
Q

T0C02 Which of the following frequencies has the lowest Maximum Permissible Exposure limit? A. 3.5 MHz B. 50 MHz C. 440 MHz D. 1296 MHz

A

B. 50 MHz

27
Q

T0C03 What is the maximum power level that an amateur radio station may use at VHF frequencies before an RF exposure evaluation is required? A. 1500 watts PEP transmitter output B. 1 watt forward power C. 50 watts PEP at the antenna D. 50 watts PEP reflected power

A

C. 50 watts PEP at the antenna

28
Q

T0C04 What factors affect the RF exposure of people near an amateur station antenna? A. Frequency and power level of the RF field B. Distance from the antenna to a person C. Radiation pattern of the antenna D. All of these choices are correct

A

D. All of these choices are correct

29
Q

T0C05 Why do exposure limits vary with frequency? A. Lower frequency RF fields have more energy than higher frequency fields B. Lower frequency RF fields do not penetrate the human body C. Higher frequency RF fields are transient in nature D. The human body absorbs more RF energy at some frequencies than at others

A

D. The human body absorbs more RF energy at some frequencies than at others

30
Q

T0C06 Which of the following is an acceptable method to determine that your station complies with FCC RF exposure regulations? A. By calculation based on FCC OET Bulletin 65 B. By calculation based on computer modeling C. By measurement of field strength using calibrated equipment D. All of these choices are correct

A

D. All of these choices are correct

31
Q

T0C07 What could happen if a person accidentally touched your antenna while you were transmitting? A. Touching the antenna could cause television interference B. They might receive a painful RF burn C. They might develop radiation poisoning D. All of these choices are correct

A

B. They might receive a painful RF burn

32
Q

T0C08 Which of the following actions might amateur operators take to prevent exposure to RF radiation in excess of FCC-supplied limits? A. Relocate antennas B. Relocate the transmitter C. Increase the duty cycle D. All of these choices are correct

A

A. Relocate antennas

33
Q

T0C09 How can you make sure your station stays in compliance with RF safety regulations? A. By informing the FCC of any changes made in your station B. By re-evaluating the station whenever an item of equipment is changed C. By making sure your antennas have low SWR D. All of these choices are correct

A

B. By re-evaluating the station whenever an item of equipment is changed

34
Q

T0C10 Why is duty cycle one of the factors used to determine safe RF radiation exposure levels? A. It affects the average exposure of people to radiation B. It affects the peak exposure of people to radiation C. It takes into account the antenna feedline loss D. It takes into account the thermal effects of the final amplifier

A

A. It affects the average exposure of people to radiation

35
Q

T0C11 What is meant by “duty cycle” when referring to RF exposure? A. The difference between lowest usable output and maximum rated output power of a transmitter B. The difference between PEP and average power of an SSB signal C. The ratio of on-air time to total operating time of a transmitted signal D. The amount of time the operator spends transmitting

A

C. The ratio of on-air time to total operating time of a transmitted signal

Technician Class (2 decks)

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