The British Radio Olympia

Radio Record, Volume III, Issue 20, 29 November 1929, Page 10

The British Radio Olympia

The Latest in Radio

HE Mecca of English radio enthusiasts, for six years, has -been the annual exhibition at Olympia. Each successive year sees new developments and these are invariably foreshadowed at Olympia. The greatest of exhibitions has just concluded and it has revealed the simple A.C. receiver, the dynamic speaker, and the portable.

-- HE sixth, and by far the most S 4 | interesting and comprehensive, radio exhibition in England was held recently at Olympia, "If it’s Radio, it's i, Olympia," was one of the ‘snappy slogans used by the ~ English Radio Manufacturers’ Association, and from all accounts it is evident that. for once a slogan can be tabloid truth. As year by year the Radio Wxhibitions succeed one another, it is noticeable that each exhibition has some outstanding feature which perhaps may be termed a phase in development, For example, last year might well have been known as a screen-grid valve year, and the show preceding that undoubtedly served to emphasise the popularity of the moving coil loud-speaker, It now seems evident that te modern trend in design of broadcast re"Geiving apparatus is "all electric" sets. Next in order of importance comes the portable set, the design and performance of which have been improved immensely since last year's exhibition. Features of Olympia. Throughout the entire exhibition, a earefully toned colour scheme in blue and gold was employed. Twenty-five small theatres weve housed under the Olympia roof, each sound-proofed from the others. These halls were for the purposes of receiving set demonstration, and it is the first time that such facilities providing for individual demonstrations, without fear of interference, have been available. To supply these halls, a specially constructed receiver and amplifier was installed, by means’ of which programmes were received and passed to each of the miniature theatres. The main feature of the B.B.C, ex‘hibit this year comprised a model

diorama depicting the course taken by a typical programme from the microphone to the receiving aerial of the ‘distant listener, A model of the latest type of broadcasting studio was also exhibited, Considerable interest was taken in the demonstrations of radiovision which took place in a small building adjoining Olympia. The visitor was enabled to see, not only the radiovised images on the screen of the cabinet, but also the transmitter at work and the studio.in which the radiovised performances were given. The trans: mitted pictures are reported to have been much clearer and larger than they were on the occasion of last year’s exhibition. The main characteristics of this year’s exhibition at Olympia were the "all-electric"? or mains operated receivers and both the electric and combined radio gramophones. In the case of the former, it is noticeable that not only that more firms are producing this class of set, but the models shown range from the modest but highly efficient two-valve set to the more luxurious five-valve. sets, the prices being surprisingly reasonable. Screen-grid valves are employed in practically all of the modern multi-valve sets, with, in some cases, a choice of super-power or pentode valve in the output stage. ‘Many eliminators that will enable less

up-to-date receivers to work from the electric supply mains were (displayed. The humble crystal set, once s0 popular, has now almost disappeared in England, and only one firm exhibited this type of receiver. Among the more novel features displayed was a set which could be earried about in a car, and operated from the dash-board. Another was worked by a dial resembling that of an automatie telephone, The required number. is dialed, and, it is claimed, the station connected to it is heard, On the whole the general tendency in present-day receiver manufacture in Wngland is towards fewer yalves and more efficient sets. The almosi complete absence of American-Manufac tured receivers at the exhibition was noticeable. This is probably beeause these sets are not adaptable to the conditions of wide wave-range which exist in England. Also, for the same reason, the one-dial controlled sets are not yet so popular in Nngland. _ Grama-Radio and Portables. NOTHER marked development of the year has been the extension of radio gramophones and the perfecting of internal appliances and simplification of control, Combined radiogramophone sets which are operated entirely from the mains, were dlisplayed by many exhibitors, Consider: able improvement was noticeable in the design and construction of the "pick-up" and tone arm, It is reported that several ingenious devices took the place of the old familiar tone-arm in the various instruments on view. Probably the greatest development shown by the radio industry this year is in regard to portables, nearly two hundred types of which were shown. Four-valve sets appeared to be in the majority, the circuit including one, and occasionally two, sereen-grid valves with a pentode in the output stage. On their first introduction these sets were designed chiefly for outdoor use, and were put up in large-sized dispateh cases, but as they have become even more popular in the home the manufacturers are providing them with wooden eabinets, which, as well as heing light enough to carry, have a very handsome appearance, . Many of these sets are entirely mains-operated, and as such are known as transportables. This type of receiver, which is completely self-con-tained, appears to be increasingly popular in England, Despite the facet that only a frame entenna is used, the efficiency of modern valves and circuits results in a very satisfactory range of reception. .

Loudspeakers, HIS year, as never befor,e the loud- . speakers have come into their own, and many and varied models were on display. The types exhibited included moving-coil speakers, shown in chassis form and mounted both on __ baffleboards and in cabinets; ordinary cone instruments in various mountings and driven by various types of reed and balanced armature wnits; linen diaphragm loudspeakers of all dimensions also actuated by a variety of drive units, and several examples of exponential horn speakers, With a few exceptions, it seems as though the old horn-type speaker has disappeared, One company exhibits as one of its \ novelties a new moving-coll loudspeaker which is said to give an improved balance to tone and a greater sensitivity, While it is certainly true that each succeeding yenr sees a greater proportion of the exhibits clearly intended to interest the von-technical listener, there was, nevertheless, much exhibited at Olympia to appeal to the homeconstructor, The "kit idea, which involves the supply of all the necessary components, is rapidly growing in favour among mannfacturers, and fhe plan has been extended to include yarious types of loudspeakers and power- supply units. The conversion of an _ ordinary gramophone to an electric-reproduction model or the combining of gramophone mechanism with a wireless receiving set also offers great scope to the enthusiastic home-constructor. The com- , ponents required, such as the pick-up and carrier, the electrically-driven turntable, moving-coil loudspeakev parts, ete,, were all exhibited in variety, Other set-building components, such as eondensers, transformers, chokes, ¢oils, ete, were displayed in profusion. One point worthy of special mention is the gradually increasing number of American manufactured components which are finding’ their way on to the English market, Notable among these are amplifying units and moving-coil loudspeakers. TPHAT this exhibition was a complete snecess, both as regards radio ‘leyelopment and popularity, is exemp'ified by the record crowds which actended Olympia, Within fifteen minutes of the opening of the exhibition, over 1000 people had passed throuvh the turnstiles, It is interesting to conjecture what new improvements future Olympie exhibitions will bring forth, expecially ag it seems apparent that an end in the progress of radio development, especially as regards reproduction, is in sight.