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Wednesday, April 9, 2014

Radio - Wanna Be a General, Part 5

Hello, Frank here.

Hi everybody. Last time we talked about SWR in relation to antennas. As mentioned last time, most people will agree the most important piece of equipment should be your antenna. It's kind of like buying a giant screen television with a computer type speaker for sound. There are as many types of antennas as you can count on all eleven of your toes. I'm going to cover the most popular ones, but there are still a gazillion other types out there.

First, your beam antenna. Your beam will focus your power and signal in a specific direction. Most beam antennas have a motor to change the direction of the antenna. Picture one of the old TV type of antennas, you know, the ones you had up on the pole? Even some of them had a motor so you could point in a different direction to locate a different broadcasting tower. Same type concept, except the beam antenna will transmit and receive. Now, these antennas are directional. But if you want to contest, and you want to transmit and receive to a specific area, this is a great way to go.

Next is your vertical antenna. Some guys use them and they get good results. But, what you see above the ground is only part of the antenna. In many cases there are wires buried just below the surface of the ground. A lot of guys use these as expedition type use. I have never actually seen one.

Probably the most common is your dipole antenna. There are multiple configurations for dipole type antennas. The most common is half the wire on one side and the other half on the other side. If you're going to focus on one band, then a single wire will work great. Now, there are dipoles that are made for multiple bands. I would guess that the dipole is probably the most common general purpose antenna that there is. If your dipole is put up correctly and the height is right, then you can transmit and receive around the globe.

Most of these antennas are 50 ohm, but a few of them are not. As I mentioned earlier, there are multiple types of antennas. The only ones you need to be concerned with at this stage are the ones that are on the test. There is something on page 32 of the Romanchik manual that I want to bring to your attention. The term NVIS means near vertical incident skywave. Yes, this could and probably would be on your test, but it's also real handy for talking to people in your own neighborhood, especially on 40 and 80 meter. Most standard dipoles work well in this configuration.

Okay, I'm going to continue on page 33 with radio wave propagation. If you plan on doing HF transmission, then you need to have a basic grasp of this subject. Solar activity affects the levels of the ionosphere and that determines how well some of the bands function. Remember, this manual just teaches the questions and answers that are on the test. If you choose to understand this information, there is no in depth discussion here, but one of the paid online teaching courses provides much more information, as do the ARRL test manuals. 

Okay, continuing on, page 35. You need to understand MUF and LUF. This is what I'm talking about with the levels of the ionosphere. You will see a lot of this information on the test, MUF especially, the different layers of the ionosphere and when signals are absorbed or reflected. Go ahead and study up through page 37. Remember, all of this information will be on the test. Pay attention to NVIS, 40 and 80 meters use it a lot.

Safety. If your piece of equipment is too hot, or if the case shocks you, then you have an internal problem in your radio. This is generally caused by RF. Properly grounding your radio will often solve this problem. You've heard this before and you will hear it again, if you don't know what you're doing, DON'T DO IT! And if you are going to do it, turn your power down low. Pay attention to SWR. Get in touch with your local ARRL chapter. Get a good mentor from your local ARRL chapter.

Okay. Next time I'm going to cover up through page 46 which is going to deal with amateur radio practices. 

We'll talk more later. 73, Frank

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