Electrical and RF Safety Flashcards
7 cards from real Ham Radio General Class Test practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Electrical and RF Safety flashcards as text
What is the recommended minimum distance from a typical 100-watt HF dipole antenna to protect people in an uncontrolled environment?
Answer: Varies by frequency but typically several feet to tens of feet depending on frequency
The safe distance from an HF dipole varies with frequency and power; FCC online calculators and the station evaluation tool help determine the specific distance required.
Which mode of operation generally has the highest average power and therefore the greatest RF exposure risk at the same PEP setting?
Answer: FM voice
FM is a constant-carrier mode, so at the same peak envelope power, FM produces the highest average power and thus the greatest sustained RF exposure.
What is the main reason that RF safety standards differ between controlled and uncontrolled environments?
Answer: People in controlled environments are trained and can take steps to limit their own exposure
Trained operators in a controlled environment can monitor and limit their own exposure, so higher field strength limits apply; uncontrolled environments protect uninformed bystanders with stricter limits.
What is the primary electrical safety risk when operating a linear amplifier that uses vacuum tubes?
Answer: Lethal high-voltage DC on the anode supply, sometimes exceeding 2,000 volts
Tube amplifiers use high-voltage DC supplies, often exceeding 2,000 volts, which is far beyond the lethal threshold and demands extreme care.
Why is it advisable to use the 'one hand in pocket' technique when probing high-voltage circuits?
Answer: To prevent a hand-to-hand current path through the heart if accidental contact occurs
Keeping one hand in your pocket eliminates the most dangerous hand-to-hand current path through the chest, reducing cardiac risk if you accidentally contact live voltage.
What effect does increasing antenna height above ground typically have on RF exposure to people on the ground below?
Answer: It decreases ground-level exposure by increasing distance and lowering the elevation angle of maximum radiation
Greater height increases the distance between the antenna and people below, and shifts the main radiation lobe to lower elevation angles that miss nearby ground-level observers.
Which of the following best describes 'RF burns'?
Answer: Tissue damage caused by localized heating when RF current flows through the body
RF burns result from the resistive heating of tissue as RF current flows through it, similar to the heating principle in a microwave oven, and can occur at relatively low voltages.