RADIO AND ITS RECEIVERS

Sun (Auckland), Volume 1, Issue 95, 13 July 1927, Page 14

RADIO AND ITS RECEIVERS

Conducted for THE SUN

2YA—THE SUPER STATION By the end of this week New Zealand radio will have moved forward a bifir step. The new Wellington station with its aerial power of 5,000 watts ranks second only to Daventry and Is not far short of that station in power. A good opening programme is arranged for Saturday, July 16. Speeches will be made by the Prime Minister, the Mayor of Wellington, and the Postmaster-General. The artists include Signor Cesaroni, Signor Truda, Mr. de Mauny, Miss Myra Sawvei, Miss Nora Green, an instrumental trio, a guitar trio, Maori songs and band numbers. The plant was designed and built by Messrs. Standard Telephones and Cables, better known by the cider name cl Western Electric Co., an international organisation whose researches into the transmission and reception of sound by electrical means have been a very big factor in the development of broadcasting. The equipment embodies the very latest improvements in radio engineering. and is with the exception of a few individual pieces of apparatus British, with the accompanying high quality of workmanship, finish and reliability. The microphones used in conjunction with the plant are the latest doublebutton carbon type, and also the condenser type will be used. The diaplirams of these microphones are so stretched that their natural resonance is up among the highest musical frequencies, and faithful reproduction will result. This type of microphone is not as sensitive as other types, but this is made up for by a speech amplifier of special design. The signals from the speech amplifier are next amplified again, and then delivered to the modulation valve, which superimposes the sound controlled vibrations on to the carrier wave. This modulated carrier wave is at a comparatively low power, and it is brought up to strength by two stages of radio frequency power

amplification, the second stage feeding the aerial with 5 k.w. of unmodulated carrier wave. The power with 100 per cent, modulation at peak output may rfse as high as 20 k.w. The carrier wave is generated by a 50-watt valve, the first stage of power amplification consists of four 250-watt air-cooled valves in parallel, and the second stage is two 10-kilowatt watercooled valves in parallel. An interesting point is use of capacity coupling between the stages to eliminate wastage of power in the generation of harmonies. Grid bias for the valves is obtained from a 250-volt generator, and the 10,000 volts needed in the last stage is got by rectifying the output from a high voltage step-up transformer. The filaments are lighted by step-down transformers from the mains. Tests that are being made now indicate the power of this wonderful new plant, and after the new officials have had time to shake down and arrange their programmes, 2YA should be more than popular with listeners. HOWLING VALVES The result of the news that Dame Nellie Melba was to be broadcast from 4QG, Brisbane, was a lesson in more than one way. It showed first of all popularity of a relay of a famous artiste, and how the prior announcement of such a programme is welcome. It also showed the need for a campaign to teach listeners that if they cannot get a station without making their sets oscillate —they certainly will not get the station if they do—and, in addition, they cause so much interference that others who often do know better gradually come up to oscillation point in their endeavours to get through, which is a comparatively easy matter to them when things are clear, and so the interference grows. As a matter of fact, toward the end of the concert the disappointed ones evidently went to bed and reception became remarkably good, as it might have been earlier in the evening if everyone had been reasonable. DEPARTMENTAL ACTION In this respect the Post and Telegraph Department has issued a ..ir-

cular giving among other tilings data for the construction of a neutralised stage of high frequency resistance. The writer has not seen the circular, but would like to help tills good movement on, and perhaps the cost of the components might help. A good unit of good components will cost somewhere in the neighbourhood of £2 and the results in increased distance and the knowledge that one is not causing interference is well worth while. Win a valve from THE SUN Hints and Tips, and you have saved a-quarter of the outlay. NOTES AND COMMENTS A LOCAL JOURNAL THE SUN received a copy of “New Zealand Radio” for July 9. This bright little paper lias much news of topical interest from various parts of the Dominion, an article on the selectivity of aerial systems and other interesting items. It seems a pity that such a journal should make the misleading statement that such and such a set is more powerful than another. This may be so under certain circumstances, and it would be, in most cases, quite possible to reverse the tables. MORE INSPECTORS NEEDED The need of more radio inspectors has been put to the writer In quite a new way recently. Two prominent dealers complained that on several occasions they, as wholesalers, have received country orders, accompanied by the purchaser’s licence number, a dealer’s licence number. After a few such orders, each for single sets or articles, and coming from districts where no radio dealer could possibly make a living, these men made inquiries and they found some people have taken out dealer’s licences in country districts where the extra fee is only a few shillings. These people then proceed to order their own gear from wholesale merchants and the difference between the retail and wholesale prices pays many times over for the extra licence fee. This partly explains the huge number of dealers in New Zealand, and is rather hard on the city merchfflnts, who pay not only a big fee as dealers, but also have to pay travellers’ licences and the many other incidental expenses of a retailer. RADIO CHANGES IN AMERICA Radio in America is now controlled by a Federal Commission which will be in charge for 12 months. After that it will continue as a court of appeal, leaving the administration to the Department of Commerce. This is merely another example of the trend toward Government control of what has become a national service. In America this change has been hastened by the confusion of too many stations. In an area of 100 miles round New York there were no less than 80 stations. In New Zealand the change is advocated for different reasons, but the general trend all over the world is for Government control. NEW ZEALAND-BUILT SETS Last week THE SUN saw a range of Australian-made components and later in the week Messrs. Hartle and Gray showed THE SUN some New Zealand-made receivers. These consisted of the solodyne and the allBritish six, two sets designed primarily at the Elstrel Laboratories under the direction of Major Robinson, D.Sc., sometime chief of the Royal Air Force Research Department. These sets are unique in being constructed of British material throughout, and this old-es-tablished firm which pioneered many British components, now well-known to amateurs, have made the construction of these two sets a labour of love THE SUN hopes to give its readers a detailed report on the performance of the all-British six at an early date. STATION EQUIPMENT IN SYDNEY Mr. Townshend. manager of Firestone Tyres and Firestone Radio, who has just returned from a trip to Sydney, expressed his disappointment at the equipment of the well-known station 2BL, and his astonishment at the lavishness of the equipment of 2FC. Rumour has it that he brought back a little device which enables him to have 2BL’s physical jerks with his breakfast. FISHING TALKS 2BL’s sporting department is broadcasting week-end fishing prospects every Friday. A short talk on various spots on the coast and what can be caught there and how to catch what is to be caught would surely be popular as an occasional talk from IYA.