Amateur Extra E0A: RF exposure and tower safety
These are the 12 official questions in group E0A of the 2024–2028 Amateur Extra question pool, with the correct answer marked and a plain-English explanation of why it's right. The real exam asks one question from this group.
Learn E0A step by stepThe Amateur Extra course teaches this group in a short guided lesson, then drills you on the questions you miss. Start with the free lessons to see how it works.
- E0A01Question 1
What is the primary function of an external earth connection or ground rod?
- APrevent static build up on power lines
- BLightning charge dissipation Correct
- CReduce RF current flow between pieces of equipment
- DProtect breaker panel from power surges
Why: A ground rod's main job is dissipating lightning charge.
- E0A02Question 2
When evaluating RF exposure levels from your station at a neighbor’s home, what must you do?
- AEnsure signals from your station are less than the controlled maximum permissible exposure (MPE) limits
- BEnsure signals from your station are less than the uncontrolled maximum permissible exposure (MPE) limits Correct
- CEnsure signals from your station are less than the controlled maximum permissible emission (MPE) limits
- DEnsure signals from your station are less than the uncontrolled maximum permissible emission (MPE) limits
Why: At a neighbor's home, keep signals below the uncontrolled MPE limits.
- E0A03Question 3
Over what range of frequencies are the FCC human body RF exposure limits most restrictive?
- A300 kHz - 3 MHz
- B3 - 30 MHz
- C30 - 300 MHz Correct
- D300 - 3000 MHz
Why: The limits are most restrictive from 30 to 300 MHz.
- E0A04Question 4
When evaluating a site with multiple transmitters operating at the same time, the operators and licensees of which transmitters are responsible for mitigating over-exposure situations?
- AEach transmitter that produces 20 percent or more of its MPE limit in areas where the total MPE limit is exceeded
- BEach transmitter operating with a duty cycle greater than 25 percent
- CEach transmitter that produces 5 percent or more of its MPE limit in areas where the total MPE limit is exceeded Correct
- DEach transmitter operating with a duty cycle greater than 50 percent
Why: Each transmitter producing 5% or more of its MPE limit where the total is exceeded shares responsibility.
- E0A05Question 5
What hazard is created by operating at microwave frequencies?
- AMicrowaves are ionizing radiation
- BThe high gain antennas commonly used can result in high exposure levels Correct
- CMicrowaves are in the frequency range where wave velocity is higher
- DThe extremely high frequency energy can damage the joints of antenna structures
Why: High-gain microwave antennas can create high exposure levels.
- E0A06Question 6
Why are there separate electric (E) and magnetic (H) MPE limits at frequencies below 300 MHz?
- AThe body reacts to electromagnetic radiation from both the E and H fields
- BGround reflections and scattering cause the field strength to vary with location
- CE field and H field radiation intensity peaks can occur at different locations
- DAll these choices are correct Correct
Why: Separate E and H limits apply for several reasons. All the choices are correct.
- E0A07Question 7
What is meant by “100% tie-off” regarding tower safety?
- AAll loose ropes and guys secured to a fixed structure
- BAt least one lanyard attached to the tower at all times Correct
- CAll tools secured to the climber’s harness
- DAll circuit breakers feeding power to the tower must be tied closed with tape, cable, or ties
Why: 100% tie-off means at least one lanyard is attached at all times.
- E0A08Question 8
What does SAR measure?
- ASignal attenuation ratio
- BSignal amplification rating
- CThe rate at which RF energy is absorbed by the body Correct
- DThe rate of RF energy reflected from stationary terrain
Why: SAR measures the rate the body absorbs RF energy.
- E0A09Question 9
Which of the following types of equipment are exempt from RF exposure evaluations?
- ATransceivers with less than 7 watts of RF output
- BAntennas that radiate only in the near field
- CHand-held transceivers sold before May 3, 2021 Correct
- DDish antennas less than one meter in diameter
Why: Handhelds sold before May 3, 2021 are exempt.
- E0A10Question 10
When must an RF exposure evaluation be performed on an amateur station operating on 80 meters?
- AAn evaluation must always be performed Correct
- BWhen the ERP of the station is less than 10 watts
- CWhen the station’s operating mode is CW
- DWhen the output power from the transmitter is less than 100 watts
Why: On 80 meters an exposure evaluation must always be performed.
- E0A11Question 11
To what should lanyards be attached while climbing?
- AAntenna mast
- BGuy brackets
- CTower rungs
- DTower legs Correct
Why: Attach lanyards to the tower legs.
- E0A12Question 12
Where should a shock-absorbing lanyard be attached to a tower when working above ground?
- AAbove the climber’s head level Correct
- BTo the belt of the fall-arrest harness
- CEven with the climber's waist
- DTo the next lowest set of guys
Why: Clip a shock-absorbing lanyard above your head level.
Learn E0A step by stepThe Amateur Extra course teaches this group in a short guided lesson, then drills you on the questions you miss. Start with the free lessons to see how it works.