THE WIRELESS WORLD

Otago Daily Times, Issue 23353, 19 November 1937, Page 2

THE WIRELESS WORLD

NEWS AND NOTES

By Magna Vox

Items of local interest are invited Dy “ Magna Vox ” for publication in tins column. It is necessary that such matter should reach this office by Tuesday of each week for insertion on 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. 3AK. Melbourne.—77o k.c., 390 metres SCL, Adelaide.—73o k.c., 411 metres. 4QG. Brisbane.—Boo k.c., 311 metres. 3YA, Christchurch. metres. 4YA. Dunedin,— 79o K.C., 379.5 metres 4YO, Dunedin.—ll4o k.c., 201 metres ANSWERS TO CORRESPONDENTS P S. McC., Dunedin. —You cannot work out the plate current unless you know both the resistance in the plate circuit and the voltage drop across this resistance. The plate current will then be found by dividing the voltage drop in volts by the resistance in ohms. One can work out problems with Ohm’s law only if two of the quantities are known. " Superhct,” Hampden, - Background noise in supers is generally due to faulty alignment, but it varies a good deal with different coil kits, etc. A very efficient kit with perfect alignment will usually play any station worth hearing long before rushing background noise is heard If, however, the aerial is inefficient, disconnected, or if the intermediates are out of alignment, then the noise may be troublesome. Try a bigger aerial and careful general adjustment, change pentagrid grid condenser and grid leak, and if still the same have the colls checked. ’’ Crystal," St. Kllda. —A selective crystal set. and one which is sufficiently sensitive to bring in all the locals (separately) is something which everyone would like to have, but Is not so simple to arrange. Additional tuning circuits usually result in such a loss of efficiency that no station can be heard at satisfactory volume. The use of a wave trap is quite in order in a unique case such as yours, where the local stations are so powerful. Doubtless you will have no difficulty in obtaining suitable constructional details of the trap DENMARK IN THE LEAD Latest figures issued by the International Broadcasting Union show that Denmark leads the world in the number of listeners in proportion to its population, one licence for every 5.2 people. Great Britain fills second place, with one licence to every 5.4 inhabitants. This, it is estimated, is better than the proportion in the United States, where the absence of licence statistics prevent accurate comparison. Italy shows up badly with only one licence to 58 of its people. Russia has one to 41, Germany one to 7.9, and France one to 10.4. NOTED BASSO TO TOUR The Australian Broadcasting Commission has received many congratulations on its enterprise in engaging Alexander Kipnis for a tour of the Commonwealth. Alexander Kipnis is regarded as one of the finest bassos in the world to-day. and is universally acknowledged as the greatest of the German opera bassos. Born in Ukralnia (South Russia), Kipnis first attracted attention as a boy soprano; then, when his voice broke, he devoted himself to the study of instrumental music, and graduated as a musical conductor at ihe Conservatorium in Warsaw. However, when he realised that his voice had developed into a fine bass, he determined to embark on a singing career. Undecided to go to Berlin or to Vienna to study for grand opera, he left the decision to fate, for he went to the railway station at Warsaw with the intention of travelling on whichever train arrived in first. The young singer bought his ticket for Berlin, and he has never regretted having left the matter to chance. Kipnis will open his tour of the Commonwealth next April, and may visit New Zealand at the conclusion of his Australian tour. EXACT TUNING In Its survey of receivers exhibited at the 1937 Radiolympiathe, the British Broadcasting Corporation gives pride of place to the technical solutions associated with ready tuning. It points out that scales have been made much larger and longer, and that in many cases the actual dial positions for the major short-wave stations are indicated. Exact tuning has been rendered more easy by the electronic tuning indicator, which has been so fitted on some of the more expensive sets as to give a croper indication of resonance even on the weakest signals. Such cathode-ray tubes are now excellently adapted to proper short-wave reception. The survey draws attention also to the growing favour of automatic tuning. This development precisely tunes in the station to which wave length the dial has been approximately tuned by the operator. LEAKAGE From the average broadcast enthusiast’s viewpoint it sounds foolish to take down the aerial periodically and clean the insulators, but from a technical view it is logic. The best type of insulator for use on an outdoor aerial is corrugated, and it should have a highly glazed or polished surface. A highly glazed suiface presents a high surface resistance, and the corrugations lengthen the distance that any current will have to travel to leak off. If dust or other elements of the air settle on the glazed surface of the insulator the surface resistance will be lowered and leakage will commence. . Therefore it is wise to clean the insulator periodically. When erecting the aerial make provisions for lowering it. During the dry weather leakage will not be so great as in wet weather SOUND EFFECTS With the development of broadcasting, and particularly the production of plays, the matter of providing background noises of a suitable nature became an important port of studio technique. The “ sound effects " department became an important pan of a studio’s organisation. It is still a prominent factor, but Its methods have changed. In the early days producers and their assistants had to display much ingenuity in devising simple arlangements for Imitating various noises. The effects department was generally a collection of all kinds of oddments which were struck, shaken, or otherwise disturbed as occasion arose. Mon" of these appliances seemingly were poor imitations of the original when seen and heard in the studio, but at the other end of the transmitting and receiving network they gave a very good impression of what they were meant to represent 'lhe general disabilities of the system in transmitting plain noises, the most difficult of all sounds to transmit faithfully, usually made up for the apparent deficiencies. To-day most of this cumbrous equipment, its dishes of water and sand that used to spill ovei the studio furniture and sc on nave dis appeared. Records have taken its place. There are enterprising concerns that have made a specialty of recording sounds of every description and an up-to-date station lays in a stock of these records and plays them or extracts from them as and when required. The variety of these records is astounding. A station of reasonable size would have a stock of about 500 They include many types of the same noise. For example, there are records of ride shots, singly, two at a time and so on. up to a pitched battle with a continuous roll of musketry, locomotives (English and American types), street noises at well-known points in various cities, wind, rain, waves breaking on the shore, riots, and hundreds of everyday, and more uncommon, sounds. For use the selected records are mounted on a battery of turntables, and their outputs fed singly or in groups as required to the common output from the studio. The handling of these records so that the proper sound comes in at exactly the right moment requires care and great skill is often necessary on the Dart of the operator in selecting a particular groove of a record and dropping the pick-up into it at the right time. To facilitate these operations special groove counters and locators and pick-up dropping mechanisms have been developed. TELEVISION DIFFICULTIES Television has been “ on the market” in London for a year, a fact which has brought forth reviews and comment. on its progress. The general opinion is that, although it has much

to its credit, its position is not as good as it might be. Within the first six months it was expected that 10,000 sets would be sold and in operation, but at the end of a year the total is probably less than half that number. It is not that the public is entirely disinterested. There have always been crowds at demonstrations. The special television display at the Science Museum, South Kensington, was one of the biggest attractions it has ever arranged. The service area of the transmission is bigger than was at first expected. The great majority of those who have seen the transmissions do not hesitate to praise the clearness and steadiness of the received image. But still it fails to gain wide approval One suggestion is that there has been a strong desire to wait and see if there is likely to be a sudden development in receivers which will make them considerably more cheaper or more effective than they have been. On the score of cheapness, the most helpful factor would be increased sales. The recent exhibition, however, has seen a marked reduction in figures in certain directions. It has also seen an improvement in the size of the received image, but generally only with an increase in cost. One very good receiver showing an image 20 inches by 16 inches is marked £193 sterling Modifications in the technical side of the transmitting equipment will allow a mechanical system of reception to be employed which will show a picture about 2ft by 2ft. The greatest retarding factor is undoubtedly the difficulty and expense of finding suitable programmes. In this respect the 8.8. C. is in a quandary whether to spend a lot on providing attractive programmes for the comparatively few set owmers, ■ thereby risking the displeasure of listeners to the ordinary services, or wait until the number of owners justifies expansion in this respect; but recent technical advances may help the programmes to be greatly improved at little or no increase of expense. A special cable which has been laid round London will allow programmes to be picked up from a variety of sources, in which respect the mobile pick-up unit will also help materially The transmission by television of items supplied to the ordinary sound broadcasting system would have the dual advantage of giving television the benefit of the experience of its programme compilers plus the publicity effect of the intimation to ordinary listeners that the items were being seen by those who owned television receivers. In the programmes the difficulty is to give set owners something comparable with that given by the talking films. Television cannot be. as broadcasting is, a more or less minor background to all kinds of other activty, Concentration on the screen is essential. Apparently it is thought that it is just as easy to go along to the local cinema with a better chance of getting a suitable programme. Another point is that television, because of its technical complexities, is bereft of the assistance of the home constructor, who in the early days of broadcasting not only gave the stations their audiences, but by his enthusiasm and results awakened the interests of others. The same strong desire to rig up his own set is there, but the technical and financial opportunities for gratifying this desire are lacking.