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The types of ham radio transmitters are generally categorized by the range of their transmission capabilities. The low-bandwidth types generally transmit between 30 and 60 megahertz (MHz), while the mid-bandwidth types transmit between 60 and 80 MHz. Other types include FM, which transmits from 88 to 108 MHz; air bandwidth with transmissions from 118 to 136 MHz; VHF, which transmits between 136 and 174 MHz; and UHF with a bandwidth of 400 to 512 MHz. Generally speaking, the most expensive top-of-the-line models within a bandwidth category are the VHF transmitters. Transmitters can come in several models, including desk-top and portable units, and they typically transmit as well as receive signals.
Different types of ham radio transmitters are available for a variety of uses. For example, if the equipment is to be operated primarily at a home or office, a desktop device is typically used. Some types of transmitters are also designed to be used while traveling to and from different locations. Some of these dual-purpose options include that are compatible with a car or truck; medium-sized portable models; and smaller hand-held ham radio transmitters similar in size to a standard walkie-talkie. The wattage of ham radio transmitters is usually commensurate with their size. Hand-held devices range from half a watt to five watts; portable transmitters fall into the five to 25-watt range; and desktop devices can run on as much as 100 watts of power.
The art of ham radio is all about having two-way conversations. To accomplish this, the transmitters also typically function as receivers. These are known as transceivers, and almost all ham radio transmitters sold today have this two-way capability.
Because many desktop and almost all portable ham radio transmitters run off atypical 13.8 volt power, they generally require a power converter when plugged into a normal household AC/DC outlet. Smaller, more modern, switching power supplies are also available and are specifically designed to handle 100-watts communications work. With regard to portable ham radio transmitters, there can be a choice of up to four different types of radio batteries: nickel-cadmium, lead gel cell, nickel metal-hydride or lithium-ion. The last category has the highest life capacity.
Within each bandwidth category, transmitters may or may not cover all modes of transmission. Most, however, cover the major types, including AM; FM; Morse Code (CW); Single Side Band (SSB); Upper Side Band (USB); and Radio Teletype (RTTY). A number of ham radio transmitters are also capable of so-called "All Mode" operation.