Ham Radio For Dummies. H. Ward Silver
you get a look at QST or CQ magazine or the many ham radio websites and social media, you’ll start to get a feel for the wide range of opportunities out there!
When you get your entry-class Technician license, you’ll probably set up a station like those in Figure 2-1. Many hams install a mobile rig in their vehicle, powering it from the battery. They often use a mag-mount antenna on the roof or trunk held on with a large magnet. You can also use these radios and antennas at home with an AC power supply and the antenna on a metal surface.
Many hams also have a small handheld radio. Figure 2-1 shows you some of the common accessories that are available. There are all sorts of batteries and battery chargers. For better range, you can use an adapter to connect a mag-mount antenna, replacing the flexible “rubber duck” antenna supplied with the radio.
Figure 2-2 shows the equipment in a station intended to operate on the “HF” or traditional “shortwave” bands. Radios are sold with a handheld microphone and an internal speaker, but you’ll have to provide your own headphones or external speaker. If you prefer Morse code (also referred to as CW for continuous wave), you can use the traditional straight key (an old-fashioned Morse code sending device), but more commonly, you use a paddle and keyer, which are much faster to use than straight keys and require less effort. (Morse code operating is discussed in Chapter 8.)
FIGURE 2-1: A typical mobile FM station and a handheld transceiver with some common accessories.
The radio is connected with a feed line to one or more antennas. Three popular antenna types — dipole, beam, and vertical — are shown. A dipole is an antenna made from wire and typically connected to its feed line in the middle. Dipoles can be held up by poles or trees. A beam antenna sends and receives radio waves in a preferred direction; it’s often mounted on a mast or tower with a rotator that can point it in different directions. Antenna switches allow the operator to select one of several antennas. An antenna tuner sits between the antenna/feed line combination and the transmitter, like a vehicle’s transmission, to make the transmitter operate at peak efficiency. If the radio doesn’t use AC line power directly, a power supply provides the DC voltage and current.
FIGURE 2-2: A typical HF (shortwave) station and a station set up to use digital communications.
A computer can be used to exchange data over the air using a digital mode. Figure 2-2 shows typical digital mode setups. Some radios have USB ports that include support for digital audio along with control of the radio. A data interface passes audio signals between the radio’s speech circuits and computer. For some types of data, a computer can’t do the necessary processing, so a modem is used. The computer talks to the modem through a COM or USB port.
Many radios are designed to be easy to use over an Internet connection as a remote station. Operating this way is called remote control. This is a perfect solution if you can’t set up a station at home. Some hams share a remote station they can all operate. There are even remote station services that provide access to excellent stations! You can get a taste of remote operating by trying some of the online receivers at www.websdr.org.
Communication Technologies
Modulation/demodulation: Modulation is the process of adding information to a radio signal so that the information can be transmitted over the air. Demodulation is the process of recovering information from a received signal. Ham radios primarily use two kinds of modulation: amplitude modulation (AM) and frequency modulation (FM), similar to what you receive on your car radio or home stereo.
Modes: A mode is a specific combination of modulation and information. You can choose among several modes when transmitting, including voice, data, video, and Morse code.
Repeaters: Repeaters are relay stations that listen on one frequency and retransmit what they hear on a different frequency. Because repeaters are often located on tall buildings, towers, or hilltops, they enable hams to use low-power radios to converse over a wide region. They can be linked by radio or the Internet to extend communication around the world. Repeaters can listen and transmit at the same time — a feature called duplex operation.
Satellites: Just like the military and commercial services, hams construct and use their own satellites. (We piggyback on commercial satellite launches; we don’t build our own rockets!) Some amateur satellites act like repeaters in the sky; others make scientific measurements, and some relay digital messages and data.
Software-Defined Radio (SDR): Microprocessors perform many of the radio’s functions, generating and receiving signals by processing them as digital data. Some radios consist almost completely of software running on a PC. SDR technology is extremely flexible and enables hams a wide variety of operating choices and features.
Networks: Hams have constructed radio-linked computer networks and a worldwide system of email servers accessed by radio. Some of the most popular voice modes consist of digitized speech routed between repeater stations over the Internet.
HAM RADIOS, CB RADIOS, AND MOBILE PHONES
Radios abound — enough to boggle your mind. Here are the differences between your ham radio and other radio services:
Citizens Band (CB): CB radio uses 40 channels near the 28 MHz ham band. CB radios are low-power and useful for local communications only, although the radio waves sometimes travel long distances. You don’t need a license to operate a CB radio. This lightly regulated service is plagued by illegal operation, which diminishes its usefulness.
Family Radio Service (FRS) and General Mobile Radio Service (GMRS): These popular radios, such as the Motorola Talkabout models, are designed for short-range communications between family members. Both operate with low power on UHF frequencies. FRS operation is unlicensed, but using the GMRS channels (see the radio’s operating manual or guide) does require a license.
Broadcasting: Although hams are often said to be broadcasting, that is incorrect. Hams are barred from doing any one-way broadcasting of programs the way that AM, FM, and TV stations do. Broadcasting without the appropriate license attracts a lot of attention from a certain government agency whose initials are FCC.
Public-safety and commercial mobile radio: The handheld and mobile radios used by police officers, firefighters, construction workers, and delivery-company couriers are similar in many ways to VHF and UHF ham radios. In fact, the