RADIO PROGRESS.

Press, Volume LXIV, Issue 19466, 13 November 1928, Page 17

RADIO PROGRESS.

♦ 2,500,000 LICENSES IN BRITAIN. NEW IDEAS AT OLYMPIA SHOW. (FBOX OTO OJTS CORRESPONDENT.) LONDON, October 2. At the end of 1923 some 158,871 people in Great Britain had paid for wireless licenses. At the end of 1927 there were 2,395,174 people licensed to use a wireless set. When it is remembered that each set supplies the needs of a whole family it is easy to see why the Wireless Exhibition held at Olympia last week was poasibla and continuously well attended. On the eve of the exhibition the Badio Manufacturers' Association held a dinner at which Sir William Bull, M.P., president of the Association, presided. He said that more than 2,500,000 families in this country had taken out wireless licences. This meant that at least one house in three had a wireless receiver. In the United States of America the corresponding proportion was one house in five. It could be taken out that in Great Britain more than 20,000,000 listened regularly or occasionally to wireless programmes. Good hearing required efficient radio receiving apparatus, well marketed and intelligently demonstrated. The British radio industry, after many vicissitudes, was now beginning to reap the reward of years of patient endeavour and difficulty. The industry, now at last centralised and united, was giving for the first time a really comprehensive and practical exhibition of all the machinery, instruments, and accessories that were available for good hearing. Not only was there a great improvement in the quality and design of radio apparatus, but there was a great increase in variety. Primarily, owing to the initiative of the Badio Manufacturers' Association in working for an abatement of royalty charges, there was this year a great reduction in price, with the result that the more efficient and elaborate apparatus was now within the reach of a much wider public. Another thing that would be discovered at Olympia was that radio manufacturers had realised that the wireless receiver was an essential part of the equipment of every" up-to-date household and should be enclosed in a cabinet. Visitors would be particularly interested also in the devices which allowed sets to be operated from the ordinary house lighting supply. Concluding, he announced that the Association had decided- to supplement and develop its exhibition work by repeating in other large cities what was now being done in London. They were taking a leading part in connexion with the exhibition at Manchester to be held this year from October 22nd to November 3rd. Senatore Marconi said the fullest development of wireless lay before them, and the future was full of promise. He thought also that it would be full of surprises. We were a long way from being able to utilise the electric wave to anything like the fullest extent. We were gradually learning how to utilise it. t Features of the Exhibition. It was not easy to pick out the most interesting features of the exhibition, but probably te radio picture and television exhibits proved the great magnet. Although almost everv manufacturer has something to show-in the direction of greater efficiency or simplicity in general receiver design, the chief interest naturally centres round certain innovations of special importance. The outstanding novelty of last year's exhibition was undoubtedly the screened valve, but, at that time, it was mainly a tool for the home constructor and had not found its way generally into the manufacturers' sets. This year many well-known manufacturers have introduced the screened valve into the high-frequency side of their receivers, with corresponding gain in amplification, stability and simplicity. A.t the same time the present exhibition has its own valve novelty, in the shape of the pentode, which is a five-electrode valve specially suitable for the output or loud-speaker stage, but, as this type of tube has been in the hands of technical workers for some time, it has been possible to incorporate it into many of the standard sets. It is said that the new pentode valve (five electrodes) gives considerable amplification, so much m fact that only one low frequency stage is necessary when this valve is used. A two valve receiver having an ordinary detector valve and a pentode m the second position is claimed to give as much magnification as the usual three valve receiver. Obvious Difficulties. "But While admitting the possibilities of the pentode, it is important to remember its disadvantages," writes an expert, "and it is my view that listeners shotild leave this valve alone until it has been proved in the hands of experimenters and those amateurs who are interested in the latest developments. "There are obvious difficulties m the manufacture of valves having five electrodes arranged closely together, and there seems something about the reproduction obtained that is unnatural. The pentode valve is at the moment not well understood. A valve of this type may be fitted in a receiver and greater volume will be obtained, but the additional noise is not necessarily desirable." . There are many receivers which have obviously been most carefully designed. There are several having two high frequency stages, and the usual amplifier which are most cleverly constructed. They have simplified tuning, are selective, and sensitive. A good price must, of course, be paid for these receivers, but they are much superior to the better types C9sting approximately the same last season. An interesting feature is the more, extended use of metal instead of wood for cabinets. A metal cabinet is satisfactory electrically and mechanically, and may be produced in attractive styles. The metal helps to shield the tuning coil and other components, with the result that a cheaper construction

is possible. Better Parts. There is ample evidence at the show that manufacturers are employing better parts than formerly. A user may therefore expect freedom from breakdown, as this is a natural result of improved designs. There are a large number of inexpensive loud speakers that give acceptable reproduction, priced at between £2 and £3- They include horn and cone types. Many of them are,attractively finished, and very suitable for employ-ment-with ordinary two and three valve receivers. A snrprisingly large number of receivers are arranged for the playing of gramophone records. The better-class instruments are self-contained, all batteries or main units and the aerial being included in the cabinet. A few instruments of this type are portable, but most of the light-weight ones are for wireless only. Many ingenious arrangements have been adopted in order to fit the com-

ponents in as small a space as possible. Four or five valves are often used in order to provide the necessary amount of magnification. These have, of course, to be chosen with due regard to their current consumption, in order that small batteries may be employed. Perhaps the most significant thing about the exhibition is the obvious trend of British manufacturers to concentrate on quality of design and manufacture. The "Stunt" set, the jerrybuilt, and the Cheap Jack set are absent. Developments Predicted. Wireless developments during th® next few years to an extent which almost defies imagination are predicted by Commander E. L. C. Grattan, R.N-> (Assistant Controller of the Central Telegraph Office of the G.P.0.). "There will be a great advanee in the wireless telephone," he said, "and it is impossible to say how far wireless photography, or even cable photography, will go. It is capable of vast development. Everything we can do by wire we should be able to do, in time, by wireless. Our chief bugbear is always atmospherics and, in beam wireless, fading periods. These should be got over in time. When one thinks of the advance of wireless from 1914 to 1918, and then from 1918 to 1928, one can hardly imagine what will be achieved by 1938. Messages and pictures will always be sent by wireless, but the cable is not dead by any means. Even now the cable is developing in its methods of transmission. The two services are developing side by side, but wireless, being the newer service, is developing more rapidly. The Beam System. "The beam service is so quick that we sometimes get a signal twice round the world. The station sends a signal, we get it here, and a moment afterwards we get the same signal again. We have methods of checking that. It is called the 'echo.'" In Commander Grattan's opinion the beam service could not have been developed so quickly but for the resources of the Post Office. It has been an enormous organisation from the beginning, dealing with something like 40,000,000 words a year. Messages are sent and received by beam wireless at the rate of 150 words a minute. More than 11,500,000 cablegrams and wireless telegrams are handled in a year in the cable room of the Central Telegraph Office, a vast appartment where the ends .of the earth are connected with London. Not only the cable services but the world-wide radio services from Rugby and the beam wireless services to Canada, Africa, Australia, and India converge in the cable room, to make it the busiest in the world. The beam services and the Imperial cable to North America and Australia are likely soon to pass from the Post Office to the Marconi and Eastern Telegraph Company, but the wireless telephone will remain. Commander Grattan took up wireless telegraphy in the Navy in 1912, and saw special service in Gallipoli, for which he was twice mentioned in despatches and awarded the D.S.O. He was afterwards in charge of wireless stations at Malta and in the United Kingdom under the Admiralty. He was appointed assistant inspector of wireless telegraphy at the G.P.O. in 1921, and for three years was in charge of the Abou Gabal wireless station near Cairo. Since January he has generally supervised the Post Office wireless and cable services.