RADIO TOPICS.

New Zealand Herald, Volume LXI, Issue 18761, 15 July 1924, Page 10

RADIO TOPICS.

'<;","" ST OTEEMI9W* : ; ; : ?2lTis3!&roJll£& BBOABOASTIHG. WorM-wide broadcasting with residents of UpSw. Paris, New York, Tokio, and Melbourne, listening-in as easily as 4hey tune to their local stations, is a matter of a few inonihs, according to the prediction of Me. H- P. Bav?*, M the Wesanghonse Electric Company. Mr. Davis says that the process of mternational broadcasting has been perfected and only requires cr-. ganisatk© to put it into actual operation and the idea has been made possible by the process of " radio repeating," which recently linked np the various stations throughout North and South America, Cuba, and the Philippines, and , from a ceotral station in Chicago, relayed concerts to all parts of theso countries. All that is necessary now to bring about reality is to establish Bpecial stations in various parts of the globe which automatically pick up and amplify signals originating thousands of miles away and pass them on to local stations, from which they will be relayed to household aerials. Frar international radio, signals are sent out on inaudible low-frequency waves which do not interfere with local broadcasting stations on account of their inaudibility. Thus a famous statesman, say, speaking in London, could face two microphones—one to broadcast his speech on an audible wave locally, the other to carry his words to various other countries on an inaudible wave to " booster " stations, which amplify and send out audible waves to be picked up by listeners within range. Hence anywhere in the world may be received the words of the speaker on the usual receiver for local broadcasting stations.

A BEMAEKABLS 3HCBOPHQNE. The perfection of an electric ultraaudible microphone : invented by Dr Pbillipit Thomas, which it h claimed _ willpexmil scientists to record sound vibrations which now are too rapid or too fzint 10, affect the hnman ear, has been aimounced. In its experimental stage the microphone has been successfully used to transmit by radio the highest notes of the voice and of musical instrument* which are ordinarily produced and reproduced as mere noises- 'It is said thai the device has been perfected to a poin/ where it could be used by vessels at sea tor' picking up warnings of foghorns or other sound warnings beyond the range of the human ear; in studying the finer sound vibrations of organs of the human body, such as the heart and brain, and in the realm of the entomologist, who has tried in vain to pick 1 up the sounds known to be made by tiny, insects but inaudible to humans. It has long been known that certain birds, insects and even animals which to the human ear are dumb, make vocal or body sounds in communicating with-each other, and officials of the American Mnsenm of Natural History have declared that the new microphone will open up a vast realm of studyto the entomologist. The > microphone Consists of a ring of insulating material on the inner side of which two tiny electrodes are set opposite. A high voltage is applied to the electrodes producing a soft, purplish glow discharge .between them. It is said that this discharge is highly sensitive to sound vibrations, flickering with the sounds and causing changes in the flow of current and thess changes can be recorded by means of .suitable apparatus. The Thomas microphone ras proved very suitable for picking np heart beats which;; when, thus broadcasted' from the American station, KDKA, were heard all over North America, and at some pointff hv Great. Britain.

TEE SGO TEST TEAKSMISSION. ' * the most successful reception of KGO's special transmission for New Zealand was that of Mr. Shipley, Harewood, Canterbury. According to a southern'exchange, on June 29 KGO was picked up by Mr. Shipley at 5 p.m. at medium strength on two valves* At 6.30 pan. the strengths had much imand on adding two audio stages the' music'was quite distinct at 100 ft. from" the*'loud speaker. At 8 p.m. the ' announcer referred to tie test with New Zealand,; and gave & Bhort address follow* lag; a vocal item by a lady singer. A summary? of the speech is as follows:-—The speaker sftid that we lived m an epoch of great" development and achievement. A iter ; years of the war the world was settling* down again in peace and prosperity. Future progress must be in the direction of making the world a better place' to live in. Speaking of great achievements, he mentioned that during the previous yreek two American aviators had. crossed America, a distance of 2852 miles, in a little ower 21 hours* flying time, and now, that evening, San Pran- ■ cieco was speaking to New Zealand. Americana knew very little of New Zealand, therefore New Zealanders \ should their country more, and this could beVaeoomplished perhaps by radio. Finally ;'£he speaker aaid that he hoped all who heard .the test would write to KGO. A, song by a gentleman concluded the programme. <$Unr->iy """ - ■ -^** r *%otes akd edqcts. The Americans call tke oscillatijag valve howls "bixdies," and of ten express their/Mse to feed them poisoned wheat. of 4YA\, Dunedin, for the remainder of July are Wy 20, Third Artillery Baad; July 26, Wraiedin Tram■walPßeSl I with supporting- vccaiists. For the special Marconi telephony test held recently between England and Austrt£mK v V&> power used was ApOO watts of 92 metres. The beam I systeni sol',,transmission: was not. fully, 'signals being moare or less broadcasted: With a five-valve receiver thrsigna,r-we ro heard 2ft. from obones; ii?he distance covered; was 12,000 miles anft'the time taken for the voice to | distance 1-15 second. : _ j A» u a 1 4rejsuH of a successful experiment in ]&JBeag*, it is proposed to install a wireplant at Rugby, England, whereby it ,jhm mieaded to connect telephone suban(i '!*?* *ork*.-Two-■way coJQversation will bo possible. IYB Ibroadeasted a complete service from a local church on Sunday evening. The and the organ came through rwelH A sermon transmitted .from 4YA on the aavme evening was plainly heard in AwjklancL '.<■' A r»dIo get should not be placed near a Sonice of heat as it is harmful to dry cell batteries. , Asa' aerial ishooid be. kept tight so that & -fa not free to swing. If the aerial or i&» fead-in has free movement, every swing will a * fcer fc ke capacity of the system and slightly alter > the taming. Thin causes fading of the signals. Constructional work on the high-power Imperial Wireless station at Rngby, -England,. Xa proceeding apace. The aerial wsll be supported on twelve masts, each SOft. high, and i 3 about a mile and ahalf long and about half-a-mDe wide. The power plant wUI consist of motor generators arranged to give high tension and direct current output of 1000 kilo-. WifflfiS af&ny voltage which may be re4000 and 18,000 volts. A higfexfrpqueucy generator will be bid up ond<#*aWß>of valves arranged in such a •way as to deal with an output of from kilowatts. An earth screen, 20ft .in height, will be provided. Efforts ar 4 J jPKmg I Mirde to have the station ready for operation by the end of the present MejSolisfceners-in are aware that burning the filaments of their valves at more voltage will materially shorten''its life, but it is not generally known Mat too high a plate current has ihe ° same effect. Those familiar with transmitting valves know that the plates can be overloaded, and while this is often donft, attempt to increase radiation, it Modetinniental to the life of the valve. While an overload is not as severe on a receiving valve, it is sofficMintly important to deserve some consideration. Overloading the plate can be done in two ways, (11 by using very "high plate volt&gtt. J2j by. using- moderate - plate, vol- ;/ tsigewithout using a C-batAery to give |v /correct grid bias* . (