. QST . icator unit forthe Model 261 (it has a separate number, 262)uses a variable resistor as a multiplier, with cali-bration points for 10, 100 and 1000 watts full-scale reading marked on the resistor scale. TheModel 263 indicator uses an individual factory-adjusted variable resistor for each of the samethree ranges and selects them with a switch. Themeter calibration is in watts and is the same onboth indicators — 0-10, 0-100, and 0-1000 —and the same type of meter is used in both. Theactual power delivered to a load is found by tak-ing the difference between the forward and re-flected pow
. QST . icator unit forthe Model 261 (it has a separate number, 262)uses a variable resistor as a multiplier, with cali-bration points for 10, 100 and 1000 watts full-scale reading marked on the resistor scale. TheModel 263 indicator uses an individual factory-adjusted variable resistor for each of the samethree ranges and selects them with a switch. Themeter calibration is in watts and is the same onboth indicators — 0-10, 0-100, and 0-1000 —and the same type of meter is used in both. Theactual power delivered to a load is found by tak-ing the difference between the forward and re-flected power readings. The voltage standing-wave ratio is found by taking the ratio of theforward to reflected power and reading the cor-responding in instruction book chart. Either coupler can be left in the transmissionline continuously, provided the power does notexceed one kilowatt with an of 1 to 1. Thebridges are designed for 52-ohm lines. ^ The circuit of a measuring instrument is rarely. March 1955 43 the whole stor} of its performance, as the sourcesof error are seldom obvious. The accuracy of abridge of this type is almost entirely determinedby the selection of components and the method ofconstruction. The inside view of one of the couplerunits shows the special constructional arrange-ment adopted to maintain accuracy over thefrequency range from 3 to 225 Mc, and to pre- vent the coupler from introducing an impedancebump in the line. The insertion loss is statedto be less than db. Couplers and indicators can be obtainedseparatelJ^ The instruction book with the couplercontains circuit information for home construc-tion of an indicator unit, in case only the coupleris purchased. — G. G. The RME-100 Speech Clipper THE advantage of speech clipping should bequite well known by this time. Modulationpercentage is limited by the amplitude of themodulating wave form, rather than by averagemodulating power. The speech clipper increasesthe ratio of average modula
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectradio, bookyear1915
