Electrical Safety

1
Electrical Safety

• Amateur radios operated at high power produce
  dangerous and potentially deadly voltages and
  current. For example, it is commonly accepted
  that a voltages as low as 30 volts can cause a
  dangerous electric shock. It is very important
  to know how to work safely with electricity.

2
Lethal Current

• There is a saying in electronics that Its the
  volts that jolts, but the mills that kills.
• As little as 100 milliamperes of electrical
  current flowing through the human body is likely
  to cause death. Thats only .1 amp, and this
  kind of current is very common in radio equipment!

3
Safe Wiring

• You may find yourself installing or replacing
  an electrical outlet at some point. A typical
  modern outlet has three different wires, each
  with a different color. Each color must be
  connected correctly. Black wires go to the brass
  or gold terminals, white wires are connected to
  the silver terminals, and the bare or green wire
  is connected to the ground screw.

4
Fuses

• Fuses are extremely important safety devices.
  The purpose of a fuse in an electrical circuit is
  to interrupt power in case of overload. This may
  happen if something inside the device shorts
  causing too much current to flow. Fuses are
  usually rated by the amount of current that will
  cause them to open or blow. A 10 amp fuse will
  open if 10 or more amps flow through the circuit
  it protects. When it opens, power to the unit is
  cut off.

5
Using the Right Size Fuse

• You should always use a fuse of the correct
  size or rating. If you use a fuse rated for less
  current than that called for, the fuse will blow
  when the equipment is operating normally. If you
  use one that is rated for a higher current, it
  could cause enough current to flow through the
  device to do serious damage before the fuse
  opens. Worse yet, the heat generated could start
  a fire. For example, if you install a 20-ampere
  fuse in your transceiver in the place of a
  5-ampere fuse, excessive current could cause a
  fire or burn up the transceiver circuitry.

6
Ways to Prevent Electrical Shock

• There are several good ways to guard against
  electrical shock at your station. They include
• Using 3-wire cords and plugs for all AC powered
  equipment
• Connecting all AC powered station equipment to a
  common ground
• Using a ground-fault interrupter at each
  electrical outlet

7
Emergency Disconnect Switch

• An emergency disconnect switch will quickly cut
  off all power to your station. This may be very
  important if something goes wrong while you are
  away from your operating position. For that
  reason, the most important thing to consider when
  installing an emergency disconnect switch at your
  station is that everyone should know where it is
  and how to use it. If others in your home dont
  know where it is, they cannot turn it off in your
  absence.

8
Lightning Storms

• Lightning storms can be extremely dangerous,
  particularly to hams, because outdoor antennas
  make great lightning rods. If an antenna is hit
  by lightning, the electrical charge the lightning
  carries is headed straight for you and your
  station. When a lightning storm is expected, you
  should
• Disconnect the antenna cables from your station
  and move them away from your radio equipment
• Unplug all power cords from AC outlets
• Stop using your radio equipment and move to
  another room until the storm passes

9
Lightning and Fire

• Without a doubt, the most important reason to
  have a lightning protection system for your
  amateur radio station is fire prevention.

10
Emergency Power

• If you are able to use a 12 volt battery as a
  power source for your radio, one simple way to
  recharge the 12-volt battery if the commercial
  power is out is to connect the battery to a car's
  battery and run the engine.

11
Battery Safety

• Conventional 12-volt storage batteries are
  widely available and often used by hams as an
  emergency power source. However, they must be
  handled carefully due to the potential hazards
  they pose. Hazards presented by conventional
  12-volt storage batteries include
• They contain dangerous acid that can spill and
  cause injury if the case is broken.
• Short circuits can damage wiring and possibly
  cause a fire
• Explosive gas produced by such batteries can
  collect if not properly vented

12
Avoid Rapid Charge or Discharge of Storage
Batteries

• If a storage battery is charged or discharged
  too quickly, the battery could overheat and give
  off dangerous gas or explode. Most newer
  chargers are smart chargers that will prevent a
  too rapid charge. To prevent a battery from
  being discharged too quickly, you should use
  enough batteries in parallel to safely power your
  equipment.

13
Capacitors

• You will learn more about capacitors when you
  study for your General class license. For now,
  however, you need to know that some types of
  capacitors, such as the electrolytic capacitors
  shown here, are capable of storing an electrical
  charge of hundreds of volts, and they can remain
  charged long after power is turned off. Devices
  such as power supplies have large capacitors that
  can hold dangerous charges. Even when a power
  supply is turned off and disconnected, you might
  receive an electric shock from a stored charge in
  these capacitors if you dont know what your are
  doing. Its not on the exam, but you should
  learn how to safely discharge these capacitors.

14
Check-Up Time!

• Now lets try the questions from this group.
• You should make a note of any that you miss for
  later review.

15
T0A01

• What 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

16
T0A01 Answer - B

• Thirty volts can be dangerous, although you can
  still get a nasty shock at voltages lower than
  this.

17
T0A02

• What is the lowest amount of electrical current
  flowing through the human body that is likely to
  cause death?
• A. 10 microamperes
• B. 100 milliamperes
• C. 10 amperes
• D. 100 amperes

18
T0A02 Answer - B

• 100 milliamperes or .1 amp is enough to kill.
  That doesn't sound like much, but bear in mind
  the old saying, "It's the volts that jolts, but
  the mils that kills!"

19
T0A03

• What is connected to the green wire in a
  three-wire electrical plug?
• A. Neutral
• B. Hot
• C. Ground
• D. The white wire

20
T0A03 Answer - C

• For safety, the green wire should always be
  connected to the ground terminal.

21
T0A04

• What is the purpose of a fuse in an electrical
  circuit?
• A. To make sure enough power reaches the circuit
• B. To interrupt power in case of overload
• C. To prevent television interference
• D. To prevent shocks

22
T0A04 Answer - B

• If a circuit suddenly begins to draw too much
  power, usually due to a component failure, the
  fuse "blows" breaking the connection between the
  device and the power source. Circuit breakers do
  the same thing, but unlike fuses, they can be
  reset and do not have to be replaced.

23
T0A05

• What might happen if you install a 20-ampere
  fuse in your transceiver in the place of a
  5-ampere fuse?
• A. The larger fuse would better protect your
  transceiver from using too much current
• B. The transceiver will run cooler
• C. Excessive current could cause a fire
• D. The transceiver would not be able to produce
  as much RF output

24
T0A05 Answer - C

• Using a fuse larger than the value called for
  will allow more current to flow before it
  "blows." This could cause all kinds of damage,
  including allowing the transceiver to literally
  burn up, and could possibly start a fire as well.

25
T0A06

• What is a good way to guard against electrical
  shock at your station?
• A. Use 3-wire cords and plugs for all AC powered
  equipment
• B. Connect all AC powered station equipment to a
  common ground
• C. Use a ground-fault interrupter at each
  electrical outlet
• D. All of these answers are correct

26
T0A06 Answer - D

• All of these answers are good ways to protect
  yourself and your station from damage or injury.
  Hams often use equipment and components that
  develop high voltages and current. It is smart
  to play it safe!

27
T0A07

• What is the most important thing to consider
  when installing an emergency disconnect switch at
  your station?
• A. It must always be as near to the operator as
  possible
• B. It must always be as far away from the
  operator as possible
• C. Everyone should know where it is and how to
  use it
• D. It should be installed in a metal box to
  prevent tampering

28
T0A07 Answer - C

• An emergency disconnect allows you to "pull the
  plug" on all connected equipment instantly.
  Everyone in your home should know how to do this
  because you may not be around when it needs to be
  done.

29
T0A08

• What precautions should be taken when a
  lightning storm is expected?
• A. Disconnect the antenna cables from your
  station and move them away from your radio
  equipment
• B. Unplug all power cords from AC outlets
• C. Stop using your radio equipment and move to
  another room until the storm passes
• D. All of these answers are correct

30
T0A08 Answer - D

• All of these answers are correct. No good can
  come from a lightning bolt surging through your
  equipment. The easiest path for a lightning bolt
  to your radio is the outside antenna. Disconnect
  it. The next best path is through your home
  wiring, so you should always unplug your
  equipment and any other valuable appliances when
  a storm is approaching. Finally, if you are
  connected to your equipment when lightning
  strikes, need we say more?

31
T0A09

• What is one way to recharge a 12-volt battery if
  the commercial power is out?
• A. You cannot recharge a battery unless the power
  is back on
• B. Add water to the battery
• C. Connect the battery to a car's battery and run
  the engine
• D. Take your battery to the utility company for a
  recharge

32
T0A09 Answer - C

• If your 12 volt battery is running low and the
  power is out, you can always recharge it using
  jumper cables from your car's battery.

33
T0A10

• What kind of hazard is presented by a
  conventional 12-volt storage battery?
• A. It contains dangerous acid that can spill and
  cause injury
• B. Short circuits can damage wiring and possibly
  cause a fire
• C. Explosive gas can collect if not properly
  vented
• D. All of these answers are correct

34
T0A10 Answer - D

• All of these answers are correct. 12 volt
  batteries are great for emergency power, but they
  are somewhat dangerous. Dangers include acid
  spills, shorts, and unvented gasses.

35
T0A11

• What can happen if a storage battery is charged
  or discharged too quickly?
• A. The battery could overheat and give off
  dangerous gas or explode
• B. The terminal voltage will oscillate rapidly
• C. The warranty will be voided
• D. The voltage will be reversed

36
T0A11 Answer - A

• Charging or discharging a battery too quickly
  can cause overheating and possibly dangerous gas
  that could lead to an explosion. There are all
  kinds of "smart chargers" on the market today
  that will help you to avoid this very unpleasant
  result.

37
T0A12

• What is the most important reason to have a
  lightning protection system for your amateur
  radio station?
• A. Lower insurance rates
• B. Improved reception
• C. Fire prevention
• D. Noise reduction

38
T0A12 Answer - C

• Nothing is more important than fire prevention.
  It doesn't matter how good your insurance
  happens to be. Some things simply cannot be
  replaced!

39
T0A13

• 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

40
T0A13 Answer - D

• Power supplies rely on capacitors to produce
  smooth direct current at a steady voltage. These
  capacitors can store a hefty charge long after
  the supply has been turned off. Touching the
  leads of a charged capacitor can be very
  dangerous.

41
Group T0B

• Group T0B covers antenna installation, tower
  safety, and overhead power lines.

42
Antenna Safety

• Antenna safety goes hand in hand with
  electrical safety. Installing and maintaining an
  antenna can be dangerous if you dont play it
  safe. For example, you should wear a hard hat
  and safety glasses if you are on the ground
  helping someone work on an antenna tower to
  protect your head and eyes in case something
  accidentally falls from the tower.

43
Climbing Safety

• Another good idea before climbing an antenna
  tower is to put on a good climbing safety belt
  and safety glasses. One slip and its a long way
  down to the ground! In addition, you should
  arrange for a helper or observer on the ground,
  inspect the tower for damage or loose hardware,
  and above all, make sure there are no electrical
  storms nearby.

44
Picking a Site for Your Antenna

• When you are transmitting, antennas can carry
  large high currents, so one very important
  consideration when putting up an antenna is to
  make sure people cannot accidentally come into
  contact with it. You dont want someone getting
  a dangerous shock or RF burn.

45
Antennas and Airports

• If you live close to an airport, you need to
  consult Part 97 to see whether you are close
  enough for height restrictions to be imposed on
  your antenna. (See 97.15(A))

46
Keep Antennas Away From Power Lines!

• The absolute most important safety precaution
  to observe when putting up an antenna tower is to
  look for and stay clear of any overhead
  electrical wires. If a falling antenna hits
  power lines, it can bring dangerous and damaging
  voltages into your station and could cause death
  by electrocution.

47
Safe Distance from Power Lines

• A good rule of thumb for maintaining a safe
  distance to from a power line when installing an
  antenna is to install the antenna so that if it
  falls unexpectedly, no part of it can come closer
  than 10 feet to the power wires. That is an
  absolute minimum. Any less than that, and you
  are asking for trouble.

48
Tower Guy Wires

• Most towers of any size need to have guy wires
  in place to secure the tower during high winds.
  The guy wires for an antenna tower should be
  installed strictly in accordance with the tower
  manufacturer's instructions. The engineers who
  designed the tower are in the best position to
  know how it should be done.

49
Crank-up Towers

• Crank-up towers are towers made of nested
  sections that can be raised or lowered by means
  of a hand crank or electrical motor. However,
  these nested sections can fall, so the most
  important safety rule to remember when using a
  crank-up tower is that a crank-up tower should
  never be climbed unless it is in the fully
  lowered position. If you are on a higher section
  that gives way, you not only run the risk of
  falling. You may also run a very real risk of
  having a limb severed.

50
Preventing Antenna Corrosion

• Stainless steel hardware is used on many
  antennas instead of other cheaper metals because
  stainless steel parts are much less likely to
  corrode than the cheap stuff. Corrosion not only
  damages the antennas. It also seriously affects
  your signal.

51
Towers Cannot Be Grounded Too Good!

• Separate 8 foot long ground rods for each tower
  leg, bonded to the tower and each other is the
  minimum considered to be an adequate ground for a
  tower. A good earth ground improves the
  performance of many antennas. It also serves as
  the best path to ground for electrical energy
  from a lightning strike on your tower. It is
  better to see your tower destroyed than your
  home, and much better than you!

52
Check-Up Time!

• Now lets try the questions from this group.
• You should make a note of any that you miss for
  later review.

53
T0B01

• Why should you wear a hard hat and safety
  glasses if you are on the ground helping someone
  work on an antenna tower?
• A. It is required by FCC rules
• B. To keep RF energy away from your head during
  antenna testing
• C. To protect your head and eyes in case
  something accidentally falls from the tower
• D. It is required by the electrical code

54
T0B01 Answer - C

• This is a "well, duh!" question. You wear
  safety glasses and a hard hat to protect yourself!

55
T0B02

• What is a good precaution to observe before
  climbing an antenna tower?
• A. Turn on all radio transmitters
• B. Remove all tower grounding connections
• C. Put on your safety belt and safety glasses
• D. Inform the FAA and the FCC that you are
  working on a tower

56
T0B02 Answer - C

• Here is another question with an obvious
  answer. When climbing a tower, you should wear a
  good pair of safety glasses and safety belt. The
  safety belt should be connected to the tower
  while you are working so that you will not fall
  if you slip or lose your balance.

57
T0B03

• What should you do before you climb a tower?
• A. Arrange for a helper or observer
• B. Inspect the tower for damage or loose hardware
• C. Make sure there are no electrical storms
  nearby
• D. All of these answers are correct

58
T0B03 Answer - D

• Failing to do any one of these could be fatal.
  You do not want to become a "silent key" before
  your time. (Silent key is the term used for a
  ham that has passed on.)

59
T0B04

• What is an important consideration when putting
  up an antenna?
• A. Carefully tune it for a low SWR
• B. Make sure people cannot accidentally come into
  contact with it
• C. Make sure you discard all packing material in
  a safe place
• D. Make sure birds can see it so they don't fly
  into it

60
T0B04 Answer - B

• The most important consideration in installing
  an antenna is to prevent others from coming in
  contact with it accidentally. While you are
  transmitting, the antenna is radiating power that
  can produce a significant shock hazard.

61
T0B05

• What must be considered when erecting an antenna
  near an airport?
• A. The maximum allowed height with regard to
  nearby airports
• B. The possibility of interference to aircraft
  radios
• C. The radiation angle of the signals it produces
  
• D. The polarization of signal to be radiated

62
T0B05 Answer - A

• 97.15(a)
• (a) Owners of certain antenna structures more
  than 60.96 meters (200 feet) above ground level
  at the site or located near or at a public use
  airport must notify the Federal Aviation
  Administration and register with the Commission
  as required by Part 17 of this chapter.

63
T0B06

• What is the most important safety precaution to
  observe when putting up an antenna tower?
• A. Install steps on the tower for safe climbing
• B. Insulate the base of the tower to avoid
  lightning strikes
• C. Ground the base of the tower to prevent
  lightning strikes
• D. Look for and stay clear of any overhead
  electrical wires

64
T0B06 Answer - D

• Towers do occasionally fall. If your tower
  should fall, the last place you want it to land
  is on power lines.

65
T0B07

• How should the guy wires for an antenna tower be
  installed?
• A. So each guy wire anchor point has an even
  number of wires
• B. So that no guy wire is more than 25 feet long
• C. Each guy wire must be pulled as tight as
  possible
• D. In accordance with the tower manufacturer's
  instructions

66
T0B07 Answer - D

• Tower manufacturers do not want their towers to
  fall, so they take great pains to determine the
  best anchor points for guy wires. If you ever
  shell out big bucks for a good tower, follow the
  manufacturer's instructions.

67
T0B08

• What is a safe distance from a power line to
  allow when installing an antenna?
• A. Half the width of your property unless the
  wires are at least 23 feet high
• B. 12.5 feet in most metropolitan areas
• C. 36 meters plus 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

68
T0B08 Answer - D

• Here, the most reasonable answer is also the
  correct one. When you install a tower, insure
  that it will get no closer than 10 feet to the
  nearest power line if it falls.

69
T0B09

• What is the most important safety rule to
  remember when using a crank-up tower?
• A. This type of tower must never be painted
• B. Crank up towers must be raised and lowered
  frequently to keep them properly lubricated
• C. Winch cables must be specially rated for use
  on this type of tower
• D. A crank-up tower should never be climbed
  unless it is in the fully lowered position

70
T0B09 Answer - D

• Crank up towers, as the name implies, can be
  cranked up by allowing nested sections to be
  raised. That is a great way to get a tower up,
  but it should never be climbed when it is up.
  Always climb it when it is fully lowered. The
  upper sections do not always hold up very well
  with the weight of a person, and if they give
  way, a serious vertical drop will result!

71
T0B10

• Why is stainless steel hardware used on many
  antennas instead of other metals?
• A. Stainless steel is a better electrical
  conductor
• B. Stainless steel weighs less than other metals
• C. Stainless steel parts are much less likely to
  corrode
• D. Stainless steel costs less than other metals

72
T0B10 Answer - C

• Corrosion is the enemy of any antenna, and
  stainless steel is very resistant to corrosion.

73
T0B11

• What is considered to be an adequate ground for
  a tower?
• A. A single 4 foot ground rod, driven into the
  earth no more than 12 inches from the base
• B. A screen of 120 radial wires
• C. Separate 8 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

74
T0B11 Answer - C

• The better the ground, the safer the tower.
  Separate 8 foot long ground rods for each tower
  leg, bonded to the tower and each other may sound
  like overkill, but it really is the bare minimum
  for safety.

75
Group T0C

• Group T0C covers RF hazards, radiation exposure,
  and RF heating hazards. It also covers RF safety
  issues such as proximity to antennas, recognized
  safe power levels, hand held safety, and RF
  exposure to others.

76
RF Safety

• Radio waves, including VHF and UHF waves, are a
  type of non-ionizing electromagnetic radiation.
  These waves are all around us, and they
  generally do not pose any danger. However,
  excessive exposure to strong RF energy can be
  harmful to tissue. For that reason, the FCC has
  set RF exposure limits that all amateur stations
  must comply with.

77
RF Danger Two Important Factors

• Radio waves can cause injury to the human body
  only if the combination of signal strength and
  frequency cause excessive power to be absorbed by
  the body. So to determine the risk of harm from
  RF exposure, you must know both the signal
  strength and the frequency of the RF energy.

78
Why Frequency Matters

• The frequency of an RF source must be
  considered when evaluating RF radiation exposure
  because the human body absorbs more RF energy at
  some frequencies than others. For example, the
  risk is somewhat higher at VHF frequencies than
  at HF frequencies.

79
Evaluating the Effects of RF Exposure

• Several factors affect the RF exposure of
  people near an amateur transmitter, including
• Frequency and power level of the RF field both
  must be considered.
• Distance from the antenna to a person the risk
  drops quickly as a person moves away from the
  antenna.
• Radiation pattern of the antenna this varies
  from one antenna to another. For example, a beam
  antenna has a stronger radiation pattern in the
  direction it is pointed, while a vertical
  antennas pattern is roughly the same in all
  directions.

80
When an RF Exposure Evaluation is Required

• If an amateur station is putting out less than
  a specified amount of power at a particular
  frequency, no exposure evaluation is required.
  For example, the maximum power level that an
  amateur radio station may use at frequencies
  above 30 MHz before an RF exposure evaluation is
  required is 50 watts PEP (peak envelope power) at
  the antenna. If the power level is less than 50
  watts, no evaluation is required. (See
  .13(C)(1))

81
How You Determine RF Safety Compliance

• There are several ways you can determine that
  your station complies with FCC RF exposure
  regulations, including
• Calculating the risk based on FCC OET Bulletin
  65 this publication is available online or in
  print.
• Calculating the risk using computer modeling
  software is available that will let you plug in
  the numbers and calculate for your particular
  situation.
• Measuring the field strength of your station
  using calibrated equipment.

82
RF Energys Affect on the Body

• When RF energy penetrates the body it changes
  to heat energy. With a small amount of exposure,
  this is generally harmless. However, when the
  exposure is high, the heat produced can be
  significant enough to cause burns. For example,
  if a person were to accidentally touch your
  antenna while you are transmitting, they might
  receive a painful RF burn injury.

83
Reducing RF Radiation at Your Station

• If you review your station and find that there
  is a risk of RF exposure greater than that
  allowed by the FCC, there are several actions you
  as an amateur operator can take to prevent
  exposure to RF radiation in excess of FCC
  supplied limits. They are
• Alter antenna patterns the idea is to get the
  RF energy into the air where it can get your
  signal out without coming too close to people on
  the ground. A beam pointed away from the problem
  area might be one solution.
• Relocate antennas the greatest danger of RF
  exposure is near the antenna. Raising the
  antenna, moving it to the top of your home, or
  putting it in a different location on your
  property all might get it farther away from
  people.
• Change station parameters such as frequency or
  power if you cant move the antenna or change
  its radiation pattern, you may be able to reduce
  power or move to bands that are within acceptable
  RF exposure limits.

84
Check-Up Time!

• Now lets try the questions from this group.
• You should make a note of any that you miss for
  later review.

85
T0C01

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

86
T0C01 Answer - D

• VHF and UHF radiation do not produce ions, so
  they are non-ionizing radiation. However, they
  can produce significant energy that can cause a
  shock and/or burn hazard.

87
T0C02

• When can radio waves cause injury to the human
  body?
• A. Only when the frequency is below 30 MHz
• B. Only if the combination of signal strength and
  frequency cause excessive power to be absorbed
• C. Only when the frequency is greater than 30 MHz
  
• D. Only when transmitter power exceeds 50 watts

88
T0C02 Answer - B

• The signal strength required to produce injury
  depends on the frequency. It also depends on how
  close the person is to the radiator - the antenna.

89
T0C03

• What is the maximum power level that an amateur
  radio station may use at frequencies above 30 MHz
  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

90
T0C03 Answer - C

• 97.13(c)(1)
• This subsection contains a table that specifies
  when an RF exposure evaluation is required. For
  all frequencies above 30 MHz, that level is 50
  watts PEP.

91
T0C04

• What factors affect the RF exposure of people
  near an amateur transmitter?
• 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 answers are correct

92
T0C04 Answer - D

• All of these factors affect the potential RF
  exposure a person may be subject to.

93
T0C05

• Why must the frequency of an RF source be
  considered when evaluating RF radiation exposure?
• 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 and do not affect the human body
• D. The human body absorbs more RF energy at some
  frequencies than others

94
T0C05 Answer - D

• The amount of energy absorbed by the human body
  is not the same at all frequencies, so frequency
  has to be considered in evaluating radiation
  exposure.

95
T0C06

• 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

96
T0C06 Answer - D

• 97.13(c)(1)
• There are several ways to determine whether your
  station complies with FCC rules regarding RF
  exposure. All of the above can help you do so.
  The good news is that for the typical beginning
  Technician station, the analysis is not all that
  difficult.

97
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 injury
• C. They would be able to hear what you are saying
• D. Nothing

98
T0C07 Answer - B

• Touching an antenna while someone is
  transmitting can lead to a nasty RF burn!

99
T0C08

• What action might amateur operators take to
  prevent exposure to RF radiation in excess of FCC
  supplied limits?
• A. Alter antenna patterns
• B. Relocate antennas
• C. Change station parameters such as frequency or
  power
• D. All of these answers are correct

100
T0C08 Answer - D

• All of these answers are correct. The effect
  of all of these is to get the RF far enough away
  from humans not to pose a risk of danger.

101
T0C09

• How can you make sure your station stays in
  compliance with RF safety regulations?
• A. Compliance is not necessary
• B. By re-evaluating the station whenever an item
  of equipment is
• changed
• C. By making sure your antennas have a low SWR
• D. By installing a low pass filter

102
T0C09 Answer - B

• When you install anything that changes your
  station's transmit characteristics, you need to
  redo the evaluation. A higher power transmitter,
  a new amplifier, a new or relocated antenna could
  all cause the RF exposure potential to change and
  should be evaluated.

103
T0C10

• Which of the following units of measurement is
  used to measure RF radiation exposure?
• A. Milliwatts per square centimeter
• B. Megohms per square meter
• C. Microfarads per foot
• D. Megahertz per second

104
T0C10 Answer - A

• You want to know how much power is being
  exposed over a certain surface area. The only
  answer from these choices that gives you this
  information is milliwatts per square centimeter.

105
T0C11

• Why is duty cycle one of the factors used to
  determine safe RF radiation exposure levels?
• A. It takes into account the amount of time the
  transmitter is operating
• B. It takes into account the transmitter power
  supply rating
• C. It takes into account the antenna feed line
  loss
• D. It takes into account the thermal effects of
  the final amplifier

106
T0C11 Answer - A

• "Duty cycle" is a description of how much time
  the transmitter is actually transmitting, and
  therefore actually radiating RF. The duty cycle
  depends on the mode you are using.

107
You Did It!Now Go Out There And Ace That Test!

• This concludes Study Guide 10.
• Once you are satisfied that you can answer 80 of
  the questions in this Sub-element, you are ready
  to take your Technician exam!