- Amateur radio mobile operation
Amateur radio mobile operation refers to the use of
amateur radioequipment from a moving vehicle. An amateur radio transceiverdesigned specifically for use in vehicles is usually mounted with the microphone and control panel in reach of the driver. In the United States, such a device is typically run off of the host vehicle's 12 volt direct currentelectrical system. Mobile radios for amateur radio can be home-made by amateur radio enthusiasts, or may be purchased from an amateur radio equipment supplier and immediately used out-of-box. In the US, some amateurs modify commercial two-way radios and use them on amateur radio frequencies. Each installation would also have a vehicle-mounted antenna connected to the transceiver by a coaxial cable. Some models may have an external, separate speaker which can be positioned and oriented facing the driver to overcome ambient road noise present when driving.
Amateur radio operators were pioneers and experimenters who developed the first mobile radio equipment. Early mobile radios operated on HF bands. Some were
amplitude modulationphone (voice) radios and some used CW to send Morse codemessages when parked. Because of wavelengths in the 15- meter to 80-meter range, HF antennas were large and the antenna patterns were affected by the host vehicle's steel body. Electrical traits of antennas were modified so they would not have to be a full quarter wavelength long. Vaccuum tuberadio designs used dynamotors, a twelve volt motor that turned a electrical generatorto make high voltagedirect current electricity. Some early mobile rigs were the size of a suitcase.
Later technology evolved to use vibrators and
solid-statepower supplies in order to make high voltage for the vacuum tubes. These circuits included inverters which changed the 12V DC to AC which could be passed through a transformer to make high voltage. The high voltage side of the transformer was rectified to make DC for the vacuum tubes. A common trait of vacuum tube type mobile rigs was their heavy weight; this was partly caused by including iron-core transformers in the power supplies. High voltage power supplies were inefficient and vacuum tube filaments added to currentdemands, taxing vehicle electrical systems.
Amateur radio operators expanded the technology to work on frequency bands into UHF. Solid state equipment arrived in the 1960s, with more efficient circuitry and smaller size. By the mid 1970s, vacuum tube-type power
amplifiers had been replaced with high-power transistors. Amateur radio operators pioneered telephoneconnectivity and packet radio data communicationfrom automobiles.
Modern equipment is
microprocessorcontrolled, operates on multiple frequency bands, and has built-in options such as cross-band repeat. Mobile vehicular or ship-based systems exist today including amateur radio systems in bicycles, trucks, vans, cars, boats, or motorcycles.
* [http://users.rio.com/kg7fu/mobile.html Mobileering Information Page]
* [http://www.qsl.net/ka6wke/hfmobile.html KA6WKE's HF Mobile Web Pages]
* [http://www.qsl.net/k4mg/Radios/FT-100/FT-100.htm HF Mobile Rig - FT-100]
* [http://service.gm.com/techlineinfo/radio.html A typical installation guide for a mobile radio/telephone (General Motors Corporation)]
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