Neets Master Glossary

1-50 OFF-LINE TEST EQUIPMENT—Equipment that tests and isolates faults in modules or assemblies removed from systems [14]. OHM—The unit of electrical resistance. That value of electrical resistance through which a constant potential difference of 1 volt across the resistance will maintain a current flow of 1 ampere through the resistance [1]. OHMIC VALUE—Resistance in ohms [1]. OHMMETER—A meter used to measure resistance [3] [16]. OHM'S LAW—The current in an electrical circuit is directly proportional to the electromotive force in the circuit. The most common form of the law is E = IR, where E is the electromotive force or voltage across the circuit, I is the current flowing in the circuit, and R is the resistance of the circuit [1]. OHMS PER SQUARE—The resistance of any square area of thin film resistive material as measured between two parallel sides [14]. OILCAN TUBE—A type of planar tube, similar to the lighthouse tube, which has cooling fins. The oilcan tube is designed to handle large amounts of power at uhf frequencies [6]. OMNIDIRECTIONAL ANTENNA—An antenna that radiates and receives equally in all directions (nondirectional) [10] [18]. ON-LINE TEST EQUIPMENT—Continuously monitors the performance of electronic systems [14]. OPAQUE—Those substances that do not transmit (pass) any light rays; that is, the light rays are either absorbed or reflected [10]. OPEN CIRCUIT—(1) The condition of an electrical circuit caused by the breaking of continuity of one or more conductors of the circuit; usually an undesired condition. (2) A circuit that does not provide a complete path for the flow of current [1]. OPEN-ENDED LINE—A transmission fine that has a terminating impedance that is infinitely large [10]. OPERATIONAL AMPLIFIER (OP AMP)—An amplifier designed to perform computing or transfer operations and that has the following characteristics: (1) very high gain, (2) very high input impedance, and (3) very low output impedance [8]. OPTICAL COUPLER—A coupler composed of an LED and a photodiode and contained in a light- conducting medium. Suitable for frequencies in the low-megahertz range [7]. OPTIMUM WORKING FREQUENCY—The most practical operating frequency that can be used with the least amount of problems and is roughly 85 percent of the maximum usable frequency [10]. OPTOELECTRONIC DEVICES—Devices that either produce or use light in their operation [7]. ORDER-WIRE CIRCUIT—A circuit between operators used for operations control and coordination [17]. ORGANIZATIONAL-LEVEL MAINTENANCE (SM & R CODE O)—Responsibility of the user organization [14]. OR GATE—A gate that performs the logic OR function. It produces an output 1 whenever any or all of its inputs is/are 1 [13].