THE WIRELESS WORLD

Otago Daily Times, Issue 23511, 27 May 1938, Page 2

THE WIRELESS WORLD

NEWS AND NOTES

By Magna Vox Items of local interest are invited by ” Manna Vox ” for publication in this column. It is necessary that such matter should reach this office by Tuesday of each week for insertion in the following Friday IYA. Auckland.—6so k.c,. 461.2 metres. 2YA, Wellington.—s7o k.c.. 526 metres 2BL Sydney.—74o k.c., 405 metres. 2FC. Sydney.—6lo k.c., 476 metres 2AR Melbourne. —770 k.c.. 390 metres. SCL. Adelaide.—73o k.c.. 411 metres. 4QG, Brisbane.—Boo k.c.. 311 metres 3YA, Christchurch—72o. k.c.. 416.4 metres 4YA, Dunedin.—79o k.c., 379.5 metres 4YO. 'Dunedin.—ll4o k.c.. 261 metres ANSWERS TO CORRESPONDENTS G. McK. Dunedin—lf it is running parallel to power lines for any distance, this is probably how the hum is being picked up. Have you tried earthing the far end of the aerial through a 1000 ohm. potentiometer, and adjusting the latter for the best results? This sometimes makes an extraordinary difference in volume. D. PM. Woodhaugh.—To connect headphones to your receiver (assuming that it uses push-pull output valves), connect one side of a .01 or .02 mfd fixed condenser to the plate of each output pentode. The free pigtails on the two condensers should be taken to an output jack mounted on the back of the chassis, and well insulated from it. Then incorporate a switch on one of the leads from the secondary of the output transformer to the speaker voice coil in order to silence the latter when the 'phones are being used COLOUR TELEVISION Mr J. L. Baird, the Scottish lelevisionist. who has been visiting Australia, told an interviewer that before long it will be possible for a son in Australia to ring up his mother in England, and, while talking to her, see her in natural colours. Mr Baird claims to have colour television near perfection. The principal is something similar to that of multi-colour printing. The picture at the transmitting end is split into three primary colours—blue, red. and yellow. At the receiver these are blended, and produce all the colours of the spectrum. The transmission is carried out on ultra-short waves of six or seven metres. At present the range of ordinary television is only 25 miles, and tremendous advances will have to be made before Mr Baird’s vision of televising colour over half the globe becomes a reality A CURIOUS HITCH A curious technical hitch occurred during the televising of the 8.8. C. of Koringa, the woman Fakir, and her snakes a short time ago. The producer instructed the cameraman to track forward for r. close-up, but there was no response—a snake had entwined itself round the axle of the camera “ dolly.” Later in the proceedings the crocodile got out of hand. Koringa’s assistants edged away, but the cameraman. “ when all but he had fled,” was about to emulate their example when Koringa caught the creature by the tail and succeeded in mesmerising her pet just when it threatened to overturn the camera. NOT FOR NOTHING Naively suggesting that Lawrence Tibbett, the Metropolitan Opera baritone, might broadcast for nothing as a gesture of goodwill, a representative from one of the Auckland stations approached Mr Tibbett’s manager when the Mariposa called at the northern port last month. The manager informed the station representative that the opera singer would certainly consider singing from that station. but not for nothing. How much would Mr Tibbett require as his fee? “Five hundred,” replied the manager. " Five hundred dollars ? “ No. pounds.” EFFECT OF lONISATION Generally speaking, conditions for reception of stations on the broadcast band aire very much better at night time than during daylight. Many explanations have been put forward as to why this should be so. One of the most feasible is that the suns rays cause what is known as “ionisation ” of the atmosphere, or the charging of its atoms with tiny electrical charges. These have the effect of an electrical “blanket,” and reduce the range over which the radiated power is sufficient to operate a set at good strength. Consequently, whether the signal the set normally receives is due to the “ground" or direct wave, the “ sky," or reflected wave, or both, the strength of the signal is not so great. At night time, this ionisation effect not being present, conditions may be favourable, and big distances may be covered where there is a path of darkness between the transmitter and the receiver. LATE LISTENERS Detailed investigations by the 8.8. C. have shown that after 10 p.m. there is a rapid loss of listeners. Half those listening at 9.30 p.m. have switched off in the succeeding hour, and at H o’clock only one quarter still listen. At 11.30 p.m. onlv three per cent remain tuned in. On Saturdays the figures are different. Eighty per cent, are still listening at 10.30 p.m., and an hour later 17 per cent continues. According to analyses made by Mr W. A McNair in his book, ‘ Radio Advertising in Australia.” much the same falling off appears in Australia. The parlv evening peak of up to 80 per cent of sets in use falls to between 40 to 50 per cent, at 10 o clock. In the next half-hour it drops to between 20 and 25 per cent, and after 10.30 p.m. it decreases to between 8 and 2 per cent. On Saturdays the early P e f£ *s not as large, but at 11 0 , clock are still about 20 per cent tuned in After that there is a rapid drop APPEALS FOR CHARITY British listeners responded generously to appeals for charitable causes made in BJB.C. programmes during 1937, a grand total of £162,265 being subscribed in response to nearly 350 national and local broadcasts For the past 12 years five minutes ol every Sunday’s' programmes hayp been devoted to the appeals, which are broadcast under the *itle of The Week - Good Cause.” Special committees consider the many applications mr the use of the period. Beneficiaries of the charity concerned, as well as person? of national and local repute act as appellants—for example, two children once broadcast on behalf of the orphanage that had brought them up. The annual appeal on Christmas Day on behalf of the British Wireless for the Blind” Fund—which derives virtually all its income from listeners' contributions—heads the results for 1937 the sum received to date being £22.89/ The most generous response on record was to an appeal on behalf of BriUJi Red Cross work in Ethiopia £27.048 being contributed. PACIFIC ISLANDS NETWORK

The opening of a radio telegrapn office at Pukapuka, in the northern group of the Cook Islands, adds another to the surprisingly large number of radio stations in the South-western Pacific which arc in daily touch with New Zealand This immense area of ocean dotted with island groups has required a special organisation both for effective inter-communication and for contact with the larger centres of population, and in this the New Zealand Post Office has done much pioneei work. The Pacific Islands radio is grouped around five centres. In the Cook Group four low-powered stations on islands to the north including Pcnrhyn, 650 miles from Rarotonga, maintain touch with the central station at Rarotonga, and four stations to the south carry out the same duty. One of these subsidiaries, Niue, is in direct contact with New Zealand. Two days steam north-east of Rarotonga is the Society Group, a French possession having a central radio station at Papeete and five outlying stations Papeete maintains communication daily with Wellington and its French outlet, Saigon. The Tongan radio system has its centre in the capital of the Friendly Islands, Nukualofa, which maintains touch with four subsidiaries in the group and with Wellington and Suva. In Western Samoa, the central station, Apia, is in touch with New Zealand, and links up with seven sub-

sidiaries in the group, extending northwards into the Union Islands. The Fiji Islands radio system comprises six subsidiary stations throughout the group, with a main station at Suva, the latter maintaining contact with Australia and Samoa by radio and with New Zealand by cable. Very little power is needed to operate a small radio transmitter. At the Chathams a wind-driven generator easily maintains the necessary supply of current The Cook Islands Administration relies upon regular supplies of dry batteries, but in its most recent addition to the Island radio service, Pukapuka, in the northern portion of the Cook Group, a wind-driven generator is utilised. A news service is broadcast every night from ZLW on short-wave, an automatic transmitter being used, operating at twenty words per minute. Although the low power subsidiary stations may not pick up this bulletin, their parent station keeps a record, and on certain days transmits them a summary of the world’s news. All these radio systems linking up isolated island groups are rendering invaluable service. HERE AND THERE A contract has been signed between the German Telefunken Company. Berlin, and the Greek Minister of Communications for the erection of a 100-kw. transmitter at Athens, a 15kw. station at Salonica, and a 5-kw. station on the island of Corfu. These three stations will operate on medium wavelengths. Athens is to have also a 10-kw. station, which will work on short waves, with special beam aerials directed to the U.S.A. and Australia, the two parts of the world where there are most Greek emigrants. The concession is for twenty-live years, during which time the stations will be operated by Telefunken, who will have the entire revenue from broadcasting. At the end of that period they will become the oroperly of die Greek Government. The King has decided chat the proceeds from the sale of records of his speech to the Empire on Christmas Day shall go to the Not-Forgotten Association. The Czechoslovakian broadcasting system which now consists of seven stations, delivers about 9000 educational lectures annually: courses in eight different languages are broadcast.

Plans, too, are undei consideration for the institution of a wireless telephone system to link Newfoundland with Canada and America on the one side, and Great Britain on the other This service would naturally aid the developrnonl of exchange broadcast programmes with the Old Country Canada, and the United States. The Government is now considering the site occupied by the Admiralty at Mount Pearl during the war years as a national broadcasting station It. is about five miles from St. John’s, the capital. If the scheme is adopted only a minimum of advertising will be accepted, and relay stations will be placed at advantageous points throughout the country