THE WIRELESS WORLD.

Otago Daily Times, Issue 19373, 8 January 1925, Page 8

THE WIRELESS WORLD.

NEWS AND NOTES. By Magna Vox. [ltems of news, comment, suggestions, etc., will be welcomed by "Magna Vox.” In order to ensure publication correspondents axe advised that letters must be received In this office not later than Tuesday evening.] A now kind of broadcasting was introduced to the radio audience recently, when C. O. Johnson, a diver for a Philadelphia salvage firm, talked from the floor of the Atlantic off a pier at Atlantic City through, broadcasting station WIP, Philadelphia.. Reports are current that the British Broadcasting Company intends to relay American broadcasting again this winter on the same lines as last year—only, it is hoped, it will bo attended by something more in the way of success. Last year most of the transmissions were ruined by overpowering atmospherics, but as KDKA, the Pittsburgh station principally relayed, has increased power enormously since last winter, better results are hoped for. If KDKA broadcasting is relayed by Chelmsford, working on 15 kilowatts, with a range of two or three thousand miles, maybe some other powerful station in the East will be able to pick him up and relay him, giving effect to the wireless engineer’s dream of putting a wireless belt round the earth. During November an International Radio Week was held in the United States, ana a scries of special programmes was sent out by the more powerful stations to ascertain whether they could fao heard in Europe. Among those which were picked up in Europe were WEBH, WON, WQI, and WFAA. These four stations, together with another powerful Chicago station, WTAY, are now to endeavour to 1 reach across to New Zealand and Aus- ! tralia. It will be necessary, owing to the I differences in time between Chicago and I Now Zealand, for the concerts to start | there at 1 o’clock in the morning, and continue till 5 a.m. I Amateurs in Adelaide recently received a ( surprise when they heard a station transi rnitting on a wave length of about 420 1 metres under the call sign 6CL. This was the Central Broadcasters (Ltd.), a new company, having taken over the station formerly run by the South Australian Broadcasting Company at the Grosvonor, North terrace, Adelaide. A new transmitter of 500 watt capacity has been in- | stalled, although up to the present the ' transmission has been very weak for the power used; no doubt improvements will be made as time goes on. Still, some very good programmes, it is reported, have been broadcasted from this station, and, considering the very short time that the proprietors have had in which to got on tho ether, they have done very well. When an A battery is fully charged, each col] reads 2.5 volts, and the specific gravity is at its highest. When discharged the battery will drop to 1.7 volts, and the gravity will drop to 1.175. It should not bo allowed to go below this, as there is not sufficient voltage to properly heat the filament and the battery has started to sulphate. The battery should he charged at once, and charged fully, not half charged, otherwise the sulphate remains on the plates. When a battery is badly sulphated it requires a long charge to break it down, and it must be charged at a slow rate, otherwise the active material in the plate may drop but. A storage battery does not “store” electricity as is commonly supposed: it is the chemical action of the plates that produce electricity when connected together. The lead sulphate covers the plates on discharge, and the acid oaunot attack the active material, therefore no current flows and the battery is run down. The Californian broadcasting station KGO (Oakland), which is heard regularly in Now Zealand on Tuesday, Wednesday, Friday, and Sunday evenings up till 8.30 o’clock, is now broadcasting girls’ halfhour talks every Friday evening. Unfortunately, they are transmitted between 5.30 and 6 o'clock Californian time, which means 1 p.m. till 1.30 p.m. (Saturday) New Zealand time—daylight reception—a rare feat by even the best receiving sets. Many interesting tilings for girls between the ages of 11 and 16 are scheduled. Talks on personality will bo among the first broadcasts. How to train the voice, a factor of personal equipment too often overlooked, will be discussed fully. Many girls of tho Californian Campfire Organisation have note books for KGO Friday evening broadcasts, in which they write down for reference many of the interesting and instructive things which they hear. What a girl should wear, the kind of shoos, hats, and dresses, are told, keeping pace with stylos. Interesting fiction stories are road. How to make home-made candies is also told. New games and how to play thorn aro explained. How to set a table, what, to do at a party, how to greet friends, how to always be charming, and interesting, and many other valuable things for girls to know are included in tho programmes. RECEPTION WITHOUT HIGH TENSION BATTERY. A great deal of interest was taken reAinlly in the publication by a British wireloss weekly paper of details of a now circuit which needs no hign tension battery. Broadly speaking, the principle of the now circuit is that four electrode valves are used, and, although there is no separate high-tension battery, it is obvious Uiat a certain amount of electric potential must be applied to the plato of the valve, and this, in the case of the new circuit, is supplied by the filament-heating accumulator. The now circuit certainly introduces a novel idea and results are claimed equally as good as on sets using orthodox hightension circuits, but whether tho wireless set of the future will be one without hightension batteries remains to be seen. THE LENGTH OF A WIRELESS WAVE. So many beginners in wireless axe confused over the meaning of wave-length that a simple explanation of how the length of a wireless wave is measured is bound to prove of interest. The length of the wave is the distance from tho crest or top, of one wave to the crest, or top, of the next one. In other words, the wave-length is tho distance between any two adjacent waves in a series of waves. This distance is calculated by reference to tho speed at which all waves travel. This speed is estimated at approximately 186,000 miles per second, which translated into metrical units, is equal’ to 500.000,000 metres per second. Thus it follows that by ascertaining the frequency at which wireless waves are transmitted from an aerial it is possible to calculate their length by dividing the speed by tho frequency. “FADING.” An American authority says “fading” is a natural phenomenon which manifests itseli especially in the reception of distant broadcasting, causing it to vary considerably in intensity and quality. The music may at one moment bo extremely loud and of good quality. Then suddenly the music will diminish in intensity and the quality become poorer, until after a few moments it becomes almost inaudible, only to return to its former intensity after another few moments. This variation may be gradual or quite rapid. . “This phenomenon is entirely uncontrollable, and one must be at the mercy of tho natural forces when listening to long distance stations. Your receiver has not become detuned. It is not necessary to twist Your dials to restore the station. Leave the dials of the receiver alone, tho station will return to its normal intensity in a f cw moments. Owners of the radiating regenerative receivers are specially urged wiTen lading occurs not to readjust their receivers. They only cause ther own receivers to oscillate, producing the beat notes and squeals so objectionable at the present time. “Atmospheric disturbances, or ‘static as it is commonly called, are due to uncontrollable atmospheric electrical disturbances, ; which affect any and every radio receiver | on any wave length that it may be tuned to at any particular time. This disturbance maifests itself in a variable noise, having at different times very characteristic tones. These tones have been classified by radio engineers as ‘grinders,’ ‘clicks,’ and ‘rumbling’ types of static. Static is more intense during the summer months than during the winter, because of the great humidity and occurrence o' thunder storms during this period. It is especially strong, oven in winter time, just before a severe storm. In fact, tho amount of static present is used by power companies to forecast the coming of a storm, and to provide for the additional load. “In general, the effect of static upon any radio receiver can bo minimised by using short outside aerials or by means of indoor aerials or loops. The smaller exposure of a short inside aerial or loop to elocto-magnetic waves or disturbances, moans that less static is picked up by such systems and therefore a more favourable signal to static radio is obtained. In summarising, when experiencing trouble with your radio receiver, it "is best to determine whether or not this trouble exists within the receiver or in the auxiliary apparatus