Since sections G0A and G0B are relatively short, I’m lumping them into one blog post. There were only a few minor changes to these questions.
RF safety principles, rules and guidelines, routine station evaluation
If you learn nothing else from this manual, I hope that you learn to be safe when setting up your station, building antennas, or operating a radio. It’s unfortunate, but hams every year lose their lives in accidents that could have been prevented. In this chapter, we will cover RF safety and electrical safety.
By RF safety, we mean safe exposure to the RF energy generated by amateur radio transmitters. One way that RF energy can affect human body tissue is that it heats body tissue. (G0A01) In reference to RF radiation exposure, “time averaging” means the total RF exposure averaged over a certain time. (G0A04)When evaluating RF exposure, a lower transmitter duty cycle permits greater short-term exposure levels. (G0A07)
All of these choices are correct when talking about properties that are important in estimating whether an RF signal exceeds the maximum permissible exposure (MPE) (G0A02):
- Its duty cycle
- Its frequency
- Its power density
If you install an indoor transmitting antenna, make sure that MPE limits are not exceeded in occupied areas. (G0A11)
How do you know if you’re being exposed to higher levels of RF radiation than you should be? One way is to measure the RF field. A calibrated field-strength meter with a calibrated antenna can be used to accurately measure an RF field. (G0A09)
To ensure compliance with RF safety regulations when transmitter power exceeds levels specified in part 97.13, an amateur operator must perform a routine RF exposure evaluation. (G0A08) All of these choices are correct for ways that you can use to determine that your station complies with FCC RF exposure regulations (G0A03):
- By calculation based on FCC OET Bulletin 65
- By calculation based on computer modeling
- By measurement of field strength using calibrated equipment
If an evaluation of your station shows RF energy radiated from your station exceeds permissible limits, you should take action to prevent human exposure to the excessive RF fields. (G0A05) If an evaluation shows that a neighbor might receive more than the allowable limit of RF exposure from the main lobe of a directional antenna, take precautions to ensure that the antenna cannot be pointed in their direction. (G0A10)
In addition to ensuring that you’re not exposed to high-energy RF fields, there are some simple precautions that you should take when installing and tuning an antenna. Turn off the transmitter and disconnect the feed line whenever you make adjustments or repairs to an antenna. (G0A12) When installing a ground-mounted antenna, it should be installed such that it is protected against unauthorized access. (G0A06)
Following safe work practices when installing or working on an antenna tower is paramount. When climbing on a tower using a safety belt or harness is to confirm that the belt is rated for the weight of the climber and that it is within its allowable service life. (G0B07)
Any person preparing to climb a tower that supports electrically powered devices should make sure all circuits that supply power to the tower are locked out and tagged. (G0B08) Soldered joints should not be used with the wires that connect the base of a tower to a system of ground rods because a soldered joint will likely be destroyed by the heat of a lightning strike. (G0B09) A good practice for lightning protection grounds is that they must be bonded together with all other grounds. (G0B11)
Safety in the ham shack: electrical shock and treatment, safety grounding, fusing, interlocks, wiring, antenna and tower safety
When wiring a “shack,” pay special attention to the currents that the circuit must supply and use the appropriate wire sizes and fuse sizes. Electrical safety inside the ham shack is covered by the National Electrical Code. (G0B14)
According to the code, AWG number 12 is the minimum wire size that may be safely used for a circuit that draws up to 20 amperes of continuous current. (G0B02) 15 amperes is the size of fuse or circuit breaker that would be appropriate to use with a circuit that uses AWG number 14 wiring. (G0B03)
For some devices, such as a linear amplifier, you may have to install a 240 VAC circuit. When doing so, remember only the two wires carrying voltage in a four-conductor connection should be attached to fuses or circuit breakers in a device operated from a 240-VAC single-phase source. (G0B01) Current flowing from one or more of the voltage-carrying wires directly to ground will cause a Ground Fault Circuit Interrupter (GFCI) to disconnect the 120 or 240 Volt AC line power to a device. (G0B05)
Another way to make the shack safer, is to properly ground your equipment. The metal enclosure of every item of station equipment must be grounded because it ensures that hazardous voltages cannot appear on the chassis. (G0B06)
Some equipment may have features that make it safer to use or maintain. For example, some power supplies have interlock switches. The purpose of a transmitter power supply interlock is to ensure that dangerous voltages are removed if the cabinet is opened. (G0B12)
Finally, consider that the lead in the solder commonly used in amateur radio equipment might constitute a hazard. One danger from lead-tin solder is that lead can contaminate food if hands are not washed carefully after handling. (G0B10)
In an emergency, you may want to power your station with batteries or an emergency power generator. Again, please do so safely. When powering your house from an emergency generator, you must disconnect the incoming utility power feed. (G0B13)
Gasoline-powered generators may emit exhaust gases that could be hazardous. For an emergency generator installation, the generator should be located in a well ventilated area. (G0B15) Danger of carbon monoxide poisoning is a primary reason for not placing a gasoline-fueled generator inside an occupied area. (G0B04)
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