Wednesday, April 10, 2013

Lesson 4- Saftey

Amateur Radio can be a fun activity, but it does involve high amounts of electricity, and radio waves. Also, if you are working on a tower, it can cause some safety issues. I'm going to talk about some safety precautions to ensure that you can have fun in this sport, but not pose a safety risk to yourselves or others.I'm going to break this down in to 3 areas, namely Physical Safety, Electronic Safety, and Radio safety.

Physical Safety

The key thing is here, always take the proper safety precautions. If you are working from a high area, use a harness strapped in to the tower/ other location. This includes working on a radio tower. Also, wear a helmet and safety glasses, even if you aren't climbing the tower itself. Most of the time these items won't be required, but the one time you do need them, you will be glad you did if the occasion requires. In general, keep your time in an exposed area limited, to keep your risk lower. Make sure there is someone else there, to help you as needed!

If you have an electrical tower, you need to keep it safe! First of all, make sure your tower is far away from electrical lines, including any antenna. Keeping any object at least 12 feet away is a good rule of thumb. This same rule applies if something should break, so make sure that you aren't going to be close no matter what happens! Make sure your tower is grounded according to local electrical codes.

Finally, a few additional tidbits. Generators need to be kept outdoors, to prevent carbon monoxide poisoning. Be careful what batteries you buy, some can outgas Hydrogen gas, which could explode if placed in the right conditions. Outdoors, these are safe. Many automobiles use such batteries. Finally, be careful of any sharp objects you use, such as knives, they might pose a safety risk if not used carefully.

Electronic Safety

Amateur radio can involve some powerful electronics, and is usually designed such that a user can service them. If you choose to service them, here's a few tips to keeping you safe.

1. Don't try to fix something if it's plugged in. This can cause significant shock damage!
2. Stay away from power lines (See Physical Safety for more info)
3. Be careful with any electronics if wet. They can cause shock damage.
4. Never directly work with AC power, unless you have been properly trained! The power in an outlet can kill you, if you don't take the proper precautions!
5. If you are making a custom device that operates on AC power, you will need to place fuse protectors in it's path, to ensure that you aren't going to damage something.

Radio Safety:

Radios produce what is called non-ionizing radiation. Essentially, that means that they don't have standard radiation. However, they can produce heat, as your microwave oven does. There are limits set to prevent this from causing any issues. First of all, any VHF station should be evaluated if it's output at the antenna will exceed 50W. The evaluation is done by another Ham. There are a variety of limits, as explained in this table from ARRL. If you think you might run in to any problems, take a look at Bulletin 65 from the FCC.

Band Power (W)
160 meters 500
80 500
40 500
30 425
20 225
17 125
15 100
12 75
10 50
6 50
2 50
1.25 50
70 cm 70
33 150
23 200
13 250
SHF (all bands) 250
EHF (all bands) 250

For my 75 W radio, if I had loss-less cable, would basically require me to be at least 2.7m, or about 9 feet, away from my radio. Furthermore, it should require that someone else is at least 20 feet away. That is assuming that I have some sort of a half wavelength antenna. The values are different if some sort of an antenna with a gain is used. Note that if you are in a car, the metal from the car should reduce the exposure to acceptable levels on the inside of the car.

If you have some sort of a gain used, such as a microwave horn, a yagi antenna, etc, you need to be even more careful. If you find that you could point your antenna in such a way that the limits would be violated, you should take precautions to ensure that you can't point in that direction, to ensure that the maximum limits are not exceeded.

Bottom line is, make sure you limit how much power you use if you are operating near another person. If you do this, you should be safe, as will your neighbors and family.

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