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Prevent static build up on power lines
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Correct AnswerLightning charge dissipation
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Reduce RF current flow between pieces of equipment
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Protect breaker panel from power surges
There are some benefits to any common ground for all of the provided options, but the key here is that it is specifically an "external earth connection or ground rod" -- in other words, this ground is actually going into the ground outside, not just into a common terminal which has been dubbed "ground" or into the house "ground".
The main reason to do that is that in the case of a lightning strike the current will take the path of least resistance to get to earth ground and you want that path to be both as short as possible and to get there much more easily than it can get to your equipment.
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Tags: arrl chapter 11 arrl module 11
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Ensure signals from your station are less than the controlled maximum permissible exposure (MPE) limits
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Correct AnswerEnsure signals from your station are less than the uncontrolled maximum permissible exposure (MPE) limits
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Ensure signals from your station are less than the controlled maximum permissible emission (MPE) limits
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Ensure signals from your station are less than the uncontrolled maximum permissible emission (MPE) limits
The two sets of exposure limits are controlled and uncontrolled. If you don't have the ability to restrict access to the area of exposure, then you must use the uncontrolled exposure limits.
In this case, you can't control where your neighbor is nor prevent him/her from being in an area of exposure, hence, you must use the uncontrolled MPE (Maximum Permissible Exposure) limits.
Hint: Don't be fooled by answers with Emission in them. Exposure is the word used in this question.
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Tags: arrl chapter 11 arrl module 11
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300 kHz - 3 MHz
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3 - 30 MHz
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Correct Answer30 - 300 MHz
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300 - 3000 MHz
FCC human body RF exposure limits are most restrictive for those frequencies where the human body may present a resonant wavelength. This is where the maximum absorption might occur.
The average height of a human male is 5' 9" or 1.75 meters. For females this is 5' 4" or 1.6 meters. This corresponds to a full wavelength of 171 to 188 MHz and a half wavelength of 85 to 94 MHz. These frequencies fall in the range of 30-300MHz.
Silly Hint: 0uch to 0uch 0uch. The answer with one zero to 2 zeros.
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Each transmitter that produces 20 percent or more of its MPE limit in areas where the total MPE limit is exceeded
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Each transmitter operating with a duty cycle greater than 25 percent
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Correct AnswerEach transmitter that produces 5 percent or more of its MPE limit in areas where the total MPE limit is exceeded
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Each transmitter operating with a duty cycle greater than 50 percent
This is an FCC rule designed to avoid arguments. In essence, any station that provides a significant portion of the transmitted power is responsible to ensure exposure limits are met.
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Tags: arrl chapter 11 arrl module 11
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Microwaves are ionizing radiation
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Correct AnswerThe high gain antennas commonly used can result in high exposure levels
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Microwaves are in the frequency range where wave velocity is higher
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The extremely high frequency energy can damage the joints of antenna structures
In the microwave range, the wavelengths are fairly small. This allows easy, inexpensive construction of high-gain antennas. The small size of the antenna can be deceptive relative to the high field strength it can generate. Caution must be used to protect people when using these antennas.
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Tags: arrl chapter 11 arrl module 11
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The body reacts to electromagnetic radiation from both the E and H fields
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Ground reflections and scattering cause the field strength to vary with location
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E field and H field radiation intensity peaks can occur at different locations
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Correct AnswerAll these choices are correct
All of these are correct and should be accounted for when considering Maximum Permissible Exposure (MPE) limits.
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Tags: arrl chapter 11 arrl module 11
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All loose ropes and guys secured to a fixed structure
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Correct AnswerAt least one lanyard attached to the tower at all times
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All tools secured to the climber’s harness
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All circuit breakers feeding power to the tower must be tied closed with tape, cable, or ties
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Signal attenuation ratio
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Signal amplification rating
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Correct AnswerThe rate at which RF energy is absorbed by the body
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The rate of RF energy reflected from stationary terrain
SAR, in this case, stands for Specific Absorption Rate. This is the rate at which the human body absorbs energy from an electromagnetic field. The SAR is affected by both frequency and body part.
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Transceivers with less than 7 watts of RF output
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Antennas that radiate only in the near field
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Correct AnswerHand-held transceivers sold before May 3, 2021
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Dish antennas less than one meter in diameter
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Correct AnswerAn evaluation must always be performed
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When the ERP of the station is less than 10 watts
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When the station’s operating mode is CW
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When the output power from the transmitter is less than 100 watts
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Antenna mast
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Guy brackets
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Tower rungs
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Correct AnswerTower legs
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Correct AnswerAbove the climber’s head level
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To the belt of the fall-arrest harness
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Even with the climber's waist
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To the next lowest set of guys
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