General Exam-Electrical and RF Safety

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General Exam-Electrical and RF Safety
2013-07-04 00:53:36
rdl gen exam g0

Amateur Radio General Exam - G0 Question Set - Electrical and RF Safety
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  1. G0A01 What is one way that RF energy can affect human body tissue?
    A. It heats body tissue
    B. It causes radiation poisoning
    C. It causes
    the blood count to reach a dangerously low level
    D. It cools body tissue
    • (A)
    • Body tissues that are subjected to very high levels of RF energy may suffer heat damage. These effects depend on the frequency of the energy, the power density of the RF field that strikes the body, and even on factors such as the polarization of the wave. The thermal effects of RF energy should not be a major concern for most radio amateurs because of the relatively low RF power we normally use and the intermittent nature of most amateur transmissions. It is rare for amateurs to be subjected to RF fields strong enough to produce thermal effects unless they are fairly close to an energized antenna or unshielded power amplifier.
  2. G0A02 Which of the following properties is important in estimating whether an RF signal exceeds the maximum permissible exposure (MPE)?
    A. Its duty cycle
    B. Its frequency
    C. Its power density
    D. All of these choices are correct
    • (D)
    • The body’s natural resonant frequencies affect how the body absorbs RF energy. For this reason, polarization, power density and the frequency of the radio signal are all important in estimating the effects of RF energy on body tissue.
  3. G0A03 [97.13(c)(1)]How can you 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
    • (D)
    • You may use any of these three procedures to determine whether your station complies with the exposure guidelines. The simplest, by far, is to perform the calculations in FCC OET Bulletin 65. There are online and software tools to help you perform the calculations. In complex or unique situations, it may be required to model or measure the exposure. [97.13(c)(1)]
  4. G0A04 What does "time averaging" mean in reference to RF radiation exposure?
    A. The average time of day when the exposure occurs
    B. The average time it takes RF radiation to have any long-term effect on the body
    C. The total time of the exposure
    D. The total RF exposure averaged over a certain time
    • (D)
    • Time averaging, when applied to RF radiation exposure, takes into account the total RF exposure averaged over either a 6-minute or a 30-minute exposure time. Time averaging compensates for the transmit/receive time ratio during normal amateur communications. It takes into account that the body cools itself after a time of reduced or no RF radiation exposure.
  5. G0A05 What must you do if an evaluation of your station shows RF energy radiated from your station exceeds permissible limits?
    A. Take action to prevent human exposure to the excessive RF fields
    B. File an Environmental Impact Statement (EIS-97) with the FCC
    C. Secure written permission from your neighbors to operate above the controlled MPE limits
    D. All of these choices are correct
    • (A)
    • Some of the things you can do to prevent human exposure to excessive RF radiation are to move your antennas farther away, restrict access to the areas where exposure would exceed the limits, or reduce power to reduce the field strengths in those areas.
  6. G0A07 What effect does transmitter duty cycle have when evaluating RF exposure?
    A. A lower transmitter duty cycle permits greater short-term exposure levels
    B. A higher
    transmitter duty cycle permits greater short-term exposure levels
    C. Low duty cycle transmitters are exempt from RF exposure evaluation requirements
    D. High duty cycle transmitters are exempt from RF exposure requirements
    • (A)
    • Since amateurs usually spend more time listening than transmitting, low duty cycles are common. Remember that including duty cycle in the exposure evaluation takes into account the reduced average transmitted power from not operating continuously at full power. This means greater short-term exposure levels can be permitted with low-duty-cycle emissions.
  7. G0A08 Which of the following steps must an amateur operator take to ensure compliance with RF safety regulations when transmitter power exceeds levels specified in part 97.13?
    A. Post a copy of FCC Part 97 in the station
    B. Post a copy of OET Bulletin 65 in the station
    C. Perform a routine RF exposure evaluation
    D. All of these choices are correct
    • (C)
    • Even if your station is exempt from the requirement, you may want to do a simple RF Radiation Exposure Evaluation. The results would demonstrate to yourself and possibly to your neighbors that your station is within the guidelines and is no cause for concern. None of the actions listed in the other answer choices would help to ensure that your station meets the FCC RF safety regulations.
  8. G0A09 What type of instrument can be used to accurately measure an RF field?
    A. A receiver with an S meter
    B. A calibrated field-strength meter with a calibrated antenna
    C. A betascope with a dummy antenna calibrated at 50 ohms
    D. An oscilloscope with a high-stability crystal marker generator
    • (B)
    • You can use a calibrated field-strength meter and calibrated field-strength sensor (antenna) to accurately measure an RF field. Even if you have access to such an expensive laboratory-grade field-strength meter, several factors can upset the readings. Reflections from the ground and nearby conductors (power lines, other antennas, house wiring, etc.) can easily confuse field-strength readings. You must know the frequency response of the test equipment and probes, and use them only within the appropriate range. Even the orientation of the test probe with respect to the polarization of the antenna being tested is important.
  9. G0A10 What is one thing that can be done if evaluation shows that a neighbor might receive more than the allowable limit of RF exposure from the main lobe of a directional antenna?
    A. Change from horizontal polarization to vertical polarization
    B. Change from horizontal polarization to circular polarization
    C. Use an antenna with a higher front-to-back ratio
    D. Take precautions to ensure that the antenna cannot be pointed in their direction
    • (D)
    • A simple way to ensure that you do not point your antenna toward a neighbor’s house while your are transmitting is to clearly mark your rotator control to remind you. Some rotator controls also have programmable “no go” regions that can prevent rotating the antenna to those directions.
  10. G0A11 What precaution should you take if you install an indoor transmitting antenna?
    A. Locate the antenna close to your operating position to minimize feed-line radiation
    B. Position the antenna along the edge of a wall to reduce parasitic radiation
    C. Make sure that MPE limits are not exceeded in occupied areas
    D. No special precautions are necessary if SSB and CW are the only modes used
    • (C)
    • You should locate any antenna (whether it is indoors or outdoors) as far away as practical from living spaces that will be occupied while you are operating. You should also perform a routine environmental evaluation to make sure that MPE limits are not exceeded in occupied areas.
  11. G0A12  What precaution should you take whenever you make adjustments or repairs to an antenna?
    A. Ensure that you and the antenna structure are grounded
    B. Turn off the transmitter and disconnect the feed line
    C. Wear a radiation badge
    D. All of these choices are correct
    • (B)
    • One way to be sure that no one can activate the transmitter while you are working on it is to turn off the transmitter power supply and disconnect the antenna feed line. If there is a chance of anyone entering the station, it is also a good idea to post a notice that you are working on the antenna.
  12. G0A13 What precaution should be taken when installing a ground-mounted antenna?
    A. It should not be installed higher than you can reach
    B. It should not be installed in a wet area
    C. It should limited to 10 feet in height
    D. It should be installed so no one can be exposed to RF radiation in excess of maximum permissible limits
    • (D)
    • No one should be near a transmitting antenna while it is in use. Install ground-mounted transmitting antennas well away from living areas so that people cannot come close enough to be exposed to more than the MPE limits. If there is a possibility of someone walking up to your antenna while you are transmitting, it may be a good idea to install a protective fence around the antenna.
  13. G0B01 Which wire or wires in a four-conductor line cord should be attached to fuses or circuit breakers in a device operated from a 240-VAC single-phase source?
    A. Only the hot wires
    B. Only the neutral wire
    C. Only the ground wire
    D. All wires
    • (A)
    • The hot wires are the only ones that should be fused. If fuses are installed in the neutral or ground lines, an overload will open the fuses or circuit breaker but will NOT remove voltage from any equipment connected to that circuit.
  14. G0B02 What is the minimum wire size that may be safely used for a circuit that draws up to 20 amperes of continuous current?
    A. AWG number 20
    B. AWG number 16
    C. AWG number 12
    D. AWG number 8
    • (C)
    • AWG number 12 wire is required for a 20-ampere circuit.
  15. G0B03 Which size of fuse or circuit breaker would be appropriate to use with a circuit that uses AWG number 14 wiring?
    A. 100 amperes
    B. 60 amperes
    C. 30 amperes
    D. 15 amperes
    • (D)
    • AWG number 14 wiring should be protected by a 15-ampere fuse or circuit breaker.
  16. G0B04 Which of the following is a primary reason for not placing a gasoline-fueled generator inside an occupied area?
    A. Danger of carbon monoxide poisoning
    B. Danger of engine over torque
    C. Lack of oxygen for adequate combustion
    D. Lack of nitrogen for adequate combustion
    • (A)
    • Carbon monoxide and other exhaust fumes can accumulate in your garage, basement or other confined living area, so ventilation is very important. Be sure not to place generators near air intakes or vents, as well.
  17. G0B05 Which of the following conditions will cause a Ground Fault Circuit Interrupter (GFCI) to disconnect the 120 or 240 Volt AC line power to a device?
    A. Current flowing from one or more of the hot wires to the neutral wire
    B. Current flowing from one or more of the hot wires directly to ground
    C. Over-voltage on the hot wire
    D. All of these choices are correct
    • (B)
    • A GFCI opens the circuit if it detects an imbalance in the currents flowing through the hot and neutral leads. The imbalance indicates that a leakage path exists from the hot connection to safety ground. That is a serious shock hazard and should be located and repaired.
  18. G0B06 Why must the metal enclosure of every item of station equipment be grounded?
    A. It prevents blowing of fuses in case of an internal short circuit
    B. It prevents signal overload
    C. It ensures that the neutral wire is grounded
    D. It ensures that hazardous voltages cannot appear on the chassis
    • (D)
    • Grounding the metal enclosure or chassis provides a path for current if there is a short circuit between the hot or neutral leads and the equipment enclosure. Without a ground connection, a shock hazard may exist if the chassis is touched.
  19. G0B07 Which of the following should be observed for safety when climbing on a tower using a safety belt or harness?
    A. Never lean back and rely on the belt alone to support your weight
    B. Always attach the belt safety hook to the belt D-ring with the hook opening away from the tower
    C. Ensure that all heavy tools are securely fastened to the belt D-ring
    D. Make sure that your belt is grounded at all times
    • (B)
    • When climbing, make sure that hooks and clips are fully latched before putting any weight on them. Then be sure that for spring-loaded devices, the gate of the hook or clip can not be opened by pressing against the tower or hardware. You might not notice that it has been accidentally unlatched!
  20. G0B08 What should be done by any person preparing to climb a tower that supports electrically powered devices?
    A. Notify the electric company that a person will be working on the tower
    B. Make sure all circuits that supply power to the tower are locked out and tagged
    C. Unground the base of the tower
    D. All of these choices are correct
    • (B)
    • Before climbing, remove power from any circuit that will not be used while you are on the tower. The best way is to remove fuses or open circuit breakers. Once the circuit is opened, lock the circuit breaker open, if possible, and tag the fuse block or breaker panel so that no one will reconnect the circuit.
  21. G0B09 Why should soldered joints not be used with the wires that connect the base of a tower to a system of ground rods?
    A. The resistance of solder is too high
    B. Solder flux will prevent a low conductivity connection
    C. Solder has too high a dielectric constant to provide adequate lightning protection
    D. A soldered joint will likely be destroyed by the heat of a lightning strike
    • (D)
    • When lightning strikes, the high current will melt the solder instantly and disconnect the ground wires. The proper way to bond ground wires to a tower is with a mechanical ground clamp.
  22. G0B10 Which of the following is a danger from lead-tin solder?
    A. Lead can contaminate food if hands are not washed carefully after handling
    B. High voltages can cause lead-tin solder to disintegrate suddenly
    C. Tin in the solder can “cold flow” causing shorts in the circuit
    D. RF energy can convert the lead into a poisonous gas
    • (A)
    • Lead is a known toxin when ingested or inhaled. Although the amount of soldering done by most amateurs does not cause enough lead exposure to be a hazard, it is a good idea to wash your hands after soldering and not eat “at the bench.”
  23. G0B11 Which of the following is good engineering practice for lightning protection grounds?
    A. They must be bonded to all buried water and gas lines
    B. Bends in ground wires must be made as close as possible to a right angle
    C. Lightning grounds must be connected to all ungrounded wiring
    D. They must be bonded together with all other grounds
    • (D)
    • Lightning protection grounds must be tied to all other safety grounds in your home and shack. Having separate ground systems can expose equipment to damage from the lightning current surge jumping between ground systems.
  24. G0B12 What is the purpose of a transmitter power supply interlock?
    A. To prevent unauthorized access to a transmitter
    B. To guarantee that you cannot accidentally transmit out of band
    C. To ensure that dangerous voltages are removed if the cabinet is opened
    D. To shut off the transmitter if too much current is drawn
    • (C)
    • High voltages are often present inside transmitter and amplifier power supplies. The interlocks on those supplies prevent you from coming in contact with energized power supply components. Interlocks often short high voltage circuits to ground when activated, providing further safety measures. Do not defeat or bypass interlock circuits unless the repair instructions specifically require you to do so.
  25. G0B13 What must you do when powering your house from an emergency generator?
    A. Disconnect the incoming utility power feed
    B. Insure that the generator is not grounded
    C. Insure that all lightning grounds are disconnected
    D. All of these choices are correct
    • (A)
    • If you do not disconnect your home's circuit breaker box from the incoming power line, called backfeeding, the power from your generator will flow back to the utility lines where it creates a shock hazard for utility workers. In addition, if utility power is restored with your generator connected to the power line, the generator may be damaged.
  26. G0B14 Which of the following is covered by the National Electrical Code?
    A. Acceptable bandwidth limits
    B. Acceptable modulation limits
    C. Electrical safety inside the ham shack
    D. RF exposure limits of the human body
    • (C)
    • The National Electrical Code covers the wiring of electrical devices,
  27. G0B15 Which of the following is true of an emergency generator installation?
    A. The generator should be located in a well ventilated area
    B. The generator should be insulated from ground
    C. Fuel should be stored near the generator for rapid refueling in case of an emergency
    D. All of these choices are correct
    • (A)
    • Carbon monoxide and other exhaust fumes can accumulate in your garage, basement or other confined living area, so ventilation is very important. Be sure not to place generators near air intakes or vents, as well.
  28. G0B16 When might a lead acid storage battery give off explosive hydrogen gas?
    A. When stored for long periods of time
    B. When being discharged
    C. When being charged
    D. When not placed on a level surface
    • (C)
    • You need to keep your lead-acid battery charged at all times for use in an emergency. A by-product of charging your battery is the release of hydrogen gas that can explode if ignited by a spark. A well-ventilated area is essential.