The Illustrated Dictionary of Electronics - Loscha

600 revolving field • Rieke chartrevolving field See ROTATING FIELD.rewind To run a magnetic tape on a transport at ahigh speed, in the direction opposite to that associatedwith the play mode.rewrite In computer operations, to return informationread from a storage location to that locationby recording.R F Symbol for FILAMENT RESISTANCE.RF Abbreviation of RADIO FREQUENCY.RF amplifier See RADIO-FREQUENCY AMPLI-FIER.RFC Abbreviation of RADIO-FREQUENCY CHOKE.RF heating See RADIO-FREQUENCY HEATING.RFI Abbreviation of RADIO-FREQUENCY INTER-FERENCE.RF inverse feedback A negative-feedback systemfor radiophone transmitters, in which a portion ofthe modulated radio-frequency (RF) signal is rectified,and the resulting direct-current voltage isfiltered and applied as bias to one of the audiostages in the proper polarity for degeneration.RF lamp A lighting lamp, used with radiofrequency(RF) alternating current, rather thanthe conventional 60-Hz utility current. This resultsin better efficiency, and allows much more light tobe generated with a given filament lamp, as comparedwith 60-Hz current.RF motion detector In security systems, an intrusiondetection and alarm system that sensesDoppler-effect-induced changes in the frequencyor phase of a radio-frequency (RF) electromagneticfield. The Doppler effect results from motionof objects in the secured area.RFO Abbreviation of radio-frequency oscillator.RF power supply See OSCILLATOR-TYPE POWERSUPPLY.RF preamplifier A sensitive, radio-frequency amplifiercircuit intended for improving the signal-tonoise(S/N) ratio in a wireless receiver. Generallyplaced between the receiver and the antenna orfeed line. Some such devices are tunable; othersare broadbanded. See also PREAMPLIFIER.RF probe See RECTIFIER PROBE.RF resistance See RADIO-FREQUENCY RESIS-TANCE.RF selectivity See RADIO-FREQUENCY SELEC-TIVITY.RF transformer See RADIO-FREQUENCY TRANS-FORMER.RF transistor See RADIO-FREQUENCY TRANSIS-TOR.R g Symbol for GRID RESISTANCE.R G Symbol for GATE RESISTANCE.RGB Abbreviation of RED-GREEN-BLUE.RGT Abbreviation of RESONANT-GATE TRANSIS-TOR.Rh Symbol for RHODIUM.R/h Abbreviation of ROENTGENS PER HOUR.R H 1. Symbol for HEATER RESISTANCE. 2. Symbolfor HOT RESISTANCE.rh Abbreviation of RELATIVE HUMIDITY.rhenium Symbol, Re. A metallic element. Atomicnumber, 75. Atomic weight, 186.207. It is used insome thermocouples.rheostat A wirewound variable dropping resistor ofthe rotary type or slider type.EndcontactAdjustablecontactEnd contactsrheostatEndcontactAdjustablecontactR HF Symbol for high-frequency resistance (seeRADIO-FREQUENCY RESISTANCE).RHI Abbreviation of RANGE-HEIGHT INDICATOR.rhodium Symbol, Rh. A metallic element. Atomicnumber, 45. Atomic weight, 102.906.rhombus A four-sided geometric plane figure, inwhich all four sides have equal length, and oppositeangles have equal measure.rhombic antenna See DIAMOND ANTENNA.rho-theta A radio-navigation system in which asingle transmitting station is used, and the positionis determined, according to polar coordinates(distance and direction).rhumbatron A RESONANT CAVITY—especiallyone in a KLYSTRON.RI Abbreviation of RADIO INTERFERENCE.R i Symbol for INPUT RESISTANCE. (Also, R in .)RIAA Abbreviation of RECORDING INDUSTRY AS-SOCIATION OF AMERICA.RIAA curve The amplitude-versus-frequency functionused in recording and reproduction of longplaying(33.3 rpm) phonograph discs, andspecified by the Recording Industry Associationof America (RIAA). The RIAA curve takes advantageof the sensitivity of the human ear at variousfrequencies to reduce the level of audible noise.ribbon microphone See VELOCITY MICROPHONE.ride gain In broadcasting, the operations of constantlyadjusting the audio modulation of thetransmitter for optimum operation.Rieke chart A visual aid, similar to the SMITHCHART, used with traveling-wave tubes in the