Ham radio receivers are more properly referred to as ham radio transceivers. These radios are used for both transmitting and receiving radio signals. There are radios that operate on only one frequency, or band, but most operate on several bands. Transceivers can be handheld, mobile, or base-station.
Ham radio bands are divided into two basic groups, high-frequency (HF) and very-high frequency (VHF). Radio frequencies are referred to by the lengths of radio waves transmitted and received. For example, a ham radio transmitter described as operating on the 70-meter wavelength will be described as a 70m radio, a high frequency. At the other end of the spectrum, a small radio operating on the 230-centimeter frequency is said to be a 230cm radio, a very high frequency.
Radios that operate on the HF bands will often be more powerful than those operating in the VHF bands. HF ham radio receivers are most often multi-band, meaning that they can operate on a larger number of frequencies. VHF transceivers may operate on only one frequency, but some will operate on as many as four.
Handheld ham radio receivers, or HTs, are about the size of a 500-page paperback book and weigh approximately 8 ounces (225 g). Their power output is usually 5 watts (W) or less, limiting their range to perhaps 5 miles (8 km). A handheld radio usually has a small, attached "rubber ducky" antenna and uses batteries as its power source, both of which also limit its capability. The most common operating frequency for these small radios is 2m, but there are several on the market that cover the 6m, 2m, 230cm, and 70cm bands.
Mobile ham radio receivers are designed to be operated from either a vehicle or a residential ham shack. These ham radio transmitters are connected to an electrical outlet or a vehicle's battery by way of the cigarette lighter or power adapter. Mobile transceivers are considerably larger and more powerful than handheld radios. Their bigger power outputs, ranging from about 50 W to 100 W, and better antennas give mobile radios a transmitting range of 200 miles (320 km) or more. Their operating frequencies range from one band, usually 2m, to the entire ham radio spectrum.
Base-station ham radio transceivers are generally quite large and can be very powerful, operating on as much as 1500 W of power. They operate on household current or a special 12-volt battery installation. More sophisticated antenna configurations are possible, allowing these ham radio receivers to transmit and receive messages over several thousand miles (km). Large base-station transceivers usually cover the entire radio spectrum, but some are designed to only operate on the high-frequency end.
The operating distances listed above are only a general guideline. Atmospheric conditions, sunspot activity, the season, and the time of day impact the way in which radio waves behave. Even a small 2m handheld transceiver can send a message several hundred miles (km) away by taking advantage of a nearby ham radio repeater.