Radio age research, manufacturing, communications, broadcasting, television (1941)

production. The large frequency span it opens up, he said, should broaden considerably the potential appli- cation of transistors. Unlike its predecessor types, it can operate in IF (intermediate frequency) stages of AM broadcast receivers, and in the video amplification stages of television receivers. Receiver Boasts Large Speaker The transistor receiver used in demonstrations by Mr. Barton has six transistors of the new radio-frequency type and three experimental junction transistors of the audio-frequency range. Although not much smaller than conventional portable radios built with tubes, the set employs the space saved by use of transistors (and miniaturized IF transformers) for a 4- by 6-inch loudspeaker. In comparing the experimental receiver with a typical portable tube receiver, Mr. Barton said the former required only one-ninth the battery power yet produced roughly twice the audio output. To show that a variety of receiver designs are possible with the new transistor, Mr. Barton has made another transistor-operated receiver that uses six stand- ard penlight batteries as a power supply good for 50 hours. This set has a smaller speaker (3 inch) and its size is less than half that of the higher performance receiver. Smaller size was achieved by sacrifice of speaker size and playing life, he said. Studies Lead to Basic Changes Dr. Mueller explained that higher frequency opera- tion of the transistor had been obtained by studying in detail the physics of the RCA audio-frequency alloy junction transistor and determining the characteristics which reduced its frequency response. As a result of these studies, he said, basic changes were made in the geometry, the type of germanium, and the alloy used. A thicker wafer of germanium is employed in order to reduce resistance between the junction region and base connection, thereby giving higher gain at higher frequencies. At the same time, the distance between the two junctions of impurity material has been markedly re- duced by drilling a hole that almost perforates the wafer, he said. The two junctions, of smaller area than in previous designs, are then formed on either side of the paper-thin layer of germanium that remains. Of great importance, also, he said, is the use of an alloying material which already contains some ger- manium. The experimental transistor type described by Dr. Mueller was of the p-n-p (positive-negative-positive) TV Problems — as Viemd m 1929 The instantaneous projection through space of light images produced directly from the object in the studio, or the scene brought to the broadcasting station through remote control, involves many problems. Special types of distribution networks, new forms of stagecraft, and a development of studio equipment and technique are required. New problems would rain in upon the broad- casting station. New forms of artistry would have to be encouraged and developed. Variety, and more variety, would be the cry of the day. The ear may be content with the oft-repeated song; the eye would be impatient with the twice-repeated scene. David Sarnoff (1929) variety. Similar methods can be used to make n-p-n transistors that operate at the higher frequencies, he said. The new radio-frequency units, he said, can provide a power amplification of about 10,000 to 1 (gain of up to 39 decibels) at 455 kilocycles, the common intermediate frequency of broadcast receivers. Their amplification is somewhat less at higher frequencies, but amplification of about 16 to 1 (gain of 12 decibels) is available at frequencies as high as 10 megacycles. The transistor may be used as an oscillator at fre- quencies as high as 40 megacycles, he added. Toscanini and NBC Symphony Open 17th Season on November 7 The NBC Symphony, under the leadership of Arturo Toscanini, will open its seventeenth season on the air with a broadcast from Carnegie Hall in New York on November 7, starting at 6:30 p.m., EST. For the sixth successive season, Guido Cantelli will share the podium with Maestro Toscanini, directing eight of the 22 sched- uled weekly concerts. Among the features planned by Toscanini for the new season are a two-part concert performance of Verdi's opera "Un Ballo in Maschera," Brahms' "German Re- quiem," Zoltan Kodaly's "Psalmus Hungaricus," and con- certs featuring the works of Sibelius, Wagner and Men- delssohn. The eight performances to be directed by Cantelli will include such works as Debussy's "The Mar- tyrdom of Saint Sebastian," Hindemith's "Concerto for Strings and Brass," and Frescobaldi's "Four Pieces." During the season, Toscanini also will direct the NBC Symphony for a number of RCA Victor recordings. 26 RADIO AGE