Radio age (May 1922-Dec 1923)

RADIO AGE — "THE MAGAZINE OF THE HOUR" ing systems now in use. Its presence in a circuit is shown by the symbol consisting of two spiral lines parallel to each other, the one in this case to the right being the primary and the other the secondary. In the illustration provision is made for two methods of varying the amount of wire in use, the proper connections for this being shown under variocoupler connections. If a coupler is used having more than seven taps, it is customary to provide two sets of switch taps, connecting them as shown. However, if there are only seven or less taps on the outer coil, they are connected by using only one switch, and taking the beginning wire, or top wire, and connecting it to the antenna, the rest going to switch-points, and the switch going to the ground. A variometer consists of two coils of wire connected in series as shown and is indicated in the circuit by a similar sign. Honeycomb coils being nothing more than a coil of wire, or inductance, are indicated by the usual sign for an inductance as in B. Sometimes they are shown in circuits by the symbol A. Resistances in circuits are practically always indicated by a jagged line, showing that that particular instrument is noninductive : i. e., does not transfer any energy to another part of the circuit by the induction phenomena. A small, blunt-headed arrow, and sometimes a thin, curled line, is used to portray the crystal detector, as shown in the chart. Meters, whether volt, galvanometer, ammeter or milliameters, are indicated by a circle, as shown. The lines on either side indicate the connecting wires. The grid leak, as shown, is a form of resistance, a very high one, indeed, and its unit of measure is usually called a Megohm. This term means one million ohms. Its construction is described elsewhere in this issue. Condensers, one of the most important instruments in radio, are indicated by two heavy parallel lines as shown. An arrow drawn through its center conveys the idea that it is variable. Audio frequency condensers are indicated somewhat differently. A condenser, it is understood, consists of two parallel conducting mediums, separated by a dielectric substance. The insulating material may be air, glass, mica or oil. Transformers, being inductances, are indicated by the conventional symbol. In this case the radio frequency transformer, having no iron core, has no lines separating the coils. Connections on these transformers are usually marked G for grid, P for plate, B or plus (+) for the B battery, and F or minus ( — ) for the negative filament. Jacks are indicated as shown, A being a two-circuit jack, while B is a single-circuit jack. They are used to plug in the headsets on detector, and first stages of multistage amplifiers, and are also used to change from phones to loud speaker. The plug when inserted to the jack pushes up the two springs, permitting the current to flow through the phones only, and opening the circuit for the remaining instruments. The tube, its socket and its various circuits are next shown, in order that the reader may become familiar with its terms. G means the zigzag wire inside of the tube, F and F the filament from where the electrons, the secret of the vacuum tube, are emitted, and P the plate. It should be remembered that nearly always a positive charge is sustained on the plate of the tube, as this is the base of its operation. For the benefit of those who are not familiar with radio terms, an oscillatory circuit is shown, which consists of a condenser and inductance in series. There is also always present another unit in this circuit, resistance, which may be in the connecting wires, in the condenser or in the inductance. Practically, the entire radio game is governed by the use of the socalled hookup, and an example is shown at the bottom of the chart. Due to the particular arrangement of the apparatus, this circuit is called the Armstrong regenerative circuit, deriving its name from its inventor, Major Armstrong. Because it has three permutations for tuning, it is sometimes called the three-circuit tuner. Referring to the diagram, we notice that the antenna is connected to the primary or outer coil of the varicoupler through the switch and the taps, and also to the ground by another set of similar taps. It is through this coil the received impulses travel, and in the course of their travel are transferred to the secondary by induction. The set Is tuned to their frequency by means of the variocoupler, and still further tuned by the use of the variometer as shown, in the "grid" circuit. Passing through the grid condenser, they are impressed on the grid of the tube, and produce a change in the plate voltage: the variation, being general. Is detected in the telephone receivers placed in the plate circuit. A variometer placed in the plate circuit, enables us to make very weak sig nals audible, due to the fact that by its adjustment in relation to the rest of the circuit, a delicate balance can be effected. The lines connecting the various symbols indicate the method used in wiring up the apparatus. The circuit diagram does not mean the apparatus must be arranged; it merely shows how these several instruments should be electrically joined. It is hoped that many of our BCL (broadcast listener) friends may benefit by this chart, and may be more intelligently enabled to read and study diagrams as they appear in the course of their radio experiences. Automatic Transmission and Reception During the last ten years, commercial companies developed automatic printing telegraph equipment for the transmission overland wires of typewiitten characters from one point to another. The present means of copying signals with the tape requires the employment of two or three extra men for translating purposes. Due to the reduction in operating personnel in the Naval Service, it became imperative to devise means to operate stations with reduced personnel. Experiments conducted in 1922 prove conclusively that automatic printing equipment could be applied to radio as well as to land wire. So much faith was placed in this new method of transmission and reception that automatic recording telegraph equipment has been installed in Naval high power circuits at San Diego, and Washington. Ireland Gets WGY That members of the Irish Constabulary arejnot always engaged in offensive or defensive operations with the Revolutionists is indicated by a letter recently received by WGY, the Schenectady station of the General Electric Company, from Harold Johnston Special Constable 11038, Ulster Special Constabulary of Barons-Court County Tyrons. Constable Johnston wrote that he picked up WGY, February 24. "Your music was very loud and exceedingly clear," wrote Mr. Johnston, "especially the Radio Quartet and last of all the bells could be heard with phones one foot from ears. We'are using a five valve receiver." Invalids Like It A letter signed "Patients of the Vermont Sanatorium," was recently received by WGY, acknowledging the pleasure and entertainment they get from the radio programs. The patients, sixty in number, are suffering from incipient tuberculosis and most of them depend upon WGY for the Sunday religious services. They wrote that they get the 7:45 p. m. concert but have to be tucked into bed at 8:30.