RADIO REVIEW (141H Year of Publication)
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he rele AN D RADIO REVIEW (141h Year of Publication) No. 397. WEDNESDAY, APRIL 6TH, 1927. VOL. XX, No. 14. Assistant Editor: Editor: Assistant Editor: F. H. HAYNES. HUGH S. POCOCK. W. JAMES. Editorial Offices : 539-40, FLEET STREET, LONDON, E.C.4 - - Editorial Telephone : City 4011 (3 lines). Advertising and Publishing Offices : DORSET HOUSE, TUDOR STREET, LONDON, E.C.4. Telephone : City 2847 (13 lines). Telegrams : "Ethaworid, Fleet, London." COVENTRY : Hertford Street. BIRMINGHAM Guildhall Buildings. Navigation Street. MANCHESTER : 199, Deansgate. Telegrams: " CyeBet Coventry." Telegrams: " Autoprees. Birm- oghnm." Telegrams: "IliYe, Manobeeter." Telephoner 5210 Coventry. Telephone: 2970 and 2971 Midland. Telephone: 8970 sad 8971 City. Subscription Rates : Home, 178. 4d.; Canada, 978. 4d.; other countries abroad, içs. 6d. per annum. As many of the circuits and apparatus described in these pages are covered by patents, readers are advised, before making use of them, to satisfy themselves that they would not be infringing patents. THE VALVE. cern should be to make the best use of them, being careful that each type is made to function under conditions most F one asked 1v11at is the most useful component favourable for its best performance. in wireless communication to -day there could The present issue of The Wireless World has been pre- be but one reply -the valve. -From small pared with the object in view of supplying this necessary iI beginnings the valve has grown in a compara- information, anti, in particular, details are given of the tively short period of receiving valves now available to 4-4-4-4-4-4-4-4,4+ 4,4-4-4-4-4- years until to -day it is the public. Looking through this regarded as the formidable list one is almost forced justly CONTENTS. i soul of wireless. Considering the PAGE to the conclusion that there are too unpretentious start which the valve EDITORIAL VIEWS ... ... 405 many types made by nearly every made and the fact that wireless at valve manufacturer, and in very that time appeared to be getting MODERN VALVE MANUFACTURE 406 f many cases the characteristics of along quite well without it, it is the By J. J. Gracie. valves are so nearly similar that more remarkable that to -day we are READERS' NOVELTIES ... ... 414 the necessity for the two types so in seems might, of completely dependent upoìl it HINTS AND TIPS FOR NEW READERS 415 doubtful. One its various forms and applications. course, go much further with the Not only is the valve used in the CHOOSING THE RIGHT VALVE 417 plea for standardisation, and say actual transmitter or receiver, but By P. K. Turner. that the time has really come when in many auxiliary directions, NEW APPARATUS ... 422 greater attention should be paid to in view especially in connection with CURRENT TOPICS ... 423 this subject, especially of broadcasting and telephone trans- the fact that an association of valve . missions. How To TEST YOUR VALVES ... ... 425 manufacturers exists which can do When will the valve reach By W. James. much to facilitate standardisation. finality in its development ? Prob- NEWS FROM THE CLUBS 429 In many directions it is obviously ably at no time in its history impossible to limit the number of will BROADCAST BREVITIES 430 such a stage be reached, for so types, but different classes of fila- many new roads are open to de- RECENT INVENTIONS ... 432 ment voltages must surely be an velopment which have limitless LETTERS TO THE EDITOR 433 exception. Here it would seem that horizons. The possibilities of READERS' PROBLEMS ... 436 it would be possible to dispense multiple electrode valves have been with alternative filament voltages developed only to a small extent, and base our requirements, say, on though there is much to be done in 4 -volt valves and so gradually this field. Substitutes for incandescent filaments will, no eliminate the 2- and 6 -volt types as time goes on. These doubt, he developed in the future to enable us to obtain additional voltage types can have comparatively little in electronic emission, and already we have the valve with an the way of advantages, and yet they account for approxi- indirectly heated cathode, although this is probably only mately two- thirds of the total number of valves which in an early stage of development ; but whilst we look are really required. forward to the future we must not neglect the present, and One final plea, which must not be overlooked, is that the valves we have at our disposal to -day are unlikely to for a standard method of valve nomenclature which is become obsolete for some considerable period. Our con - surely many years overdue. B5 .: uuíi.íöriY:.: e;uar iiPid:dzF itir t:áwawww.americanradiohistory.com : e:E.44wsr>AÙe,ìv.iLuaa....aë:.-.:f.:a;L?.me.adiciaáeieauilnù-m '°. wipa®00 - 406 wopta APRIT. 61/1, 7927. MODE-1,12N VA1 VE UFAC7U2E, . ` .' . ! N11111111111 1111111 11111110 1111.11111111111111111111111111 ! l l l I I Ì I I lÍlÍIÍI ! l I I I I I I I I I I I I I I I l I Ì Ì iiI I I I I I I I I I I I I I I I I I I I I I Ì I .1 I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I Ì I I ! I ! I I I I I I I I I ! I I I I I I I I I I I I I l Ì Í Ì ÌN I I I ' Í I I IIIII.l IIIIInIIiIIIIIIIIIÌÌIi llll!IIIIIIIIIIIIIIIIIIIIIIUIIIIIÌIIIÌIIiIIIII Constructional Details of Receiving and Transmitting Types.- By J. GRACIE. VENTS move rapidly in the world of wireless, but haust by bombardment, lasting for two hours or more, has it is doubtful if anything has changed more often given way to machine pumps fitted with high- frequency than the design and methods of manufacture of gear to volatilise the " getter," which produce highly t lermionic valves, and more particularly receiving valves, exhausted valves at the rate of 30o an hour or so, and during recent years. It seems only a short time since the what, is perhaps more interesting to the reader is the fact " R " valve was generally accepted for all purposes of that these changes, which tend all the time toward faster reception, and no other type was seriously contemplated ; production and the elimination of the " human element," to -day there are, at a modest estimate, something like tend also to an unmistakable improvement in the quality 150 different kinds of receiving valve on the market, and of the finished article. The fine clearances common enough during this period of approximately four years there have to -day between grids and filaments, the closeness and also been many other valves which have sprung up, had evenness of the grid turns in a modern high " m " valve, a brief existence, and died a natural death. the uniformity of characteristics between valve and valve It can easily be appreciated that the valve manufac- of the same type, could not be approached if one had to turer has had his hands pretty full all this time ; his job depend upon manual labour, however skilled or con- has been twofold, first to improve existing valves and to scientious. develop new ones to give better characteristics, in order Nearly all receiving valves are similar in general con- to meet the public's ever -increasing demand for quality struction, that is to say, they consist of an electrode with power, and secondly to improve his manufacturing system, mounted on support wires which pass through a technique so as to reduce costs and thereby permit a corre- glass seal, the whole arrangement being contained in a sponding reduction in selling prices. glass bulb which is exhausted as completely as possible. Manufacturing Methods -A Comparison. The electrodes are usually three in number -the filament, anode, and grid. The cathode emission is obtained either The " R " valve of four years ago took 21 hours to from the filament itself, as in the case of a bright emitter, make ; the same valve nowadays is made in rather less by raising it to a state of incandescence, or from a coating than half an hour. The old - D.E.R. (then known as on the filament, in which case the filament acts merely as the L. T. i) took about five hours to make, and required a heater of the coating. Quite recently a new type has a high degree of skill in electrode assembly, exhaust, and been marketed in which the cathode is a nickel cylinder electrical treatment; this valve is now made in about one - coated with an emissive substance and heated purely by tenth of the time, and the labour involved can be classed radiation from the filament, which is inside, but not in as unskilled throughout, a result which has been achieved contact with, the cathode. largely by the introduction of automatic machinery and The glass operations are similar to those of lamp - the use of electro-chemical means of creating vacuum, making. A length of glass tube is fed into a machine known as " getters." which simultaneously cuts the tube into short lengths and Anyone visiting a modern valve works would recognise forms a flange at one end, Fig.