Wireless-World-1959
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EtT111133 7trlldll ELECTRONICS, RADIO, TELEVISION NOVEMBER 1959 Managing Editor: 475 Editorial Comment 476 Travelling-Wave Valves - By C. H. Dix HUGH S. POCOCK, M.I.E.E. 482 " Words, Words, Words " By P. P. Eckersley Editor: 485 Short -Wave Conditions 486 World of Wireless F. L. DEVEREUX, B.Se. 488 Personalities 489 News from the Industry Assistant Editors: 491 Russian TV Production 492 F.M. Receiver By J. G. Spencer H. W. BARNARD 499 Automatic Pattern Recognition By R. L. Grimsdale T. E. IVALL 502 Voltage -Tuned Oscillator By G. W. Short 505 Transistor A.F. Oscillator By H. B. Dent 507 Letters to the Editor 508 Technical Notebook 509 Simplified Transformer Testing By J. Skinner 510 Elements of Electronic Circuits -7 By J. M. Peters 512 Reception of Space Diversity Transmitters By J. W. Koch 514 Stereophony in the Open Air 515 Missing Signposts By " Cathode Ray" VOLUME 65 NO. 10 518 Manufacturers' Products PRICE: TWO SHILLINGS 521 Transistor Stopwatch By D. E. O'N. Waddington 525 November Meetings FORTY -NINTH YEAR 526 Unbiased By " Free Grid" OF PUBLICATION 528 Random Radiations By " Diallist " Offices: Dorset House, Stamford Street, London, S.E.1 Please address to Editor, Advertisement Manager. or Publisher, as appropriate & Sons Ltd. 1959. Permission in writing from the Editor must first be obtained before letterpress or illustrations ©lliffeare reproduced from this journal. Brief abstracts or comments are allowed provided acknowledgment to the journal is given. PUBLISHED MONTHLY (4th Monday of preceding month) by ILIFFE & SONS LTD., Dorset House. Stamford Street, London, S.E.1. Waterloo 3383 (65 lines). Telegrams: Iliffepres, Sedist, London." Annual Subscriptions: Home and Overseas, £1 15s. Od. Telephone: King Canada and U.S.A., $5.00. Seeond -class mail privileges authorised at New York, N.Y. BRANCH OFFICES: BIRMINGHAM: Edward House, New Street, 2. Telephone: Midland 7191. COVENTRY: 8 -10, Corporation Street. Telephone: Coventry 25210. GLASGOW: 4412. YORK 26B, Renfield Street, C.2. Telephone: Central 1265. MANCHESTER: 260, Deansgate, 3. Telephone: Blackfriars NEW OFFICE: U.S.A.: 111, Broadway, 6. Telephone: Digby 9-1197. F www.americanradiohistory.com 114 (ADVERTISEMENT) WIRELESS WORLD NOVEMBER, 1959 UM MD DDD D VALVES FOR TELEVISION The first advertisement in this series discussed the frame grid valve in general terms, and outlined the advantages which it brings in the tuner and i.f. stages of a television receiver. We shall now look at the i.f. stages in more detail, with particular reference to the needs of fringe areas. Sand a Vision Vision ji a pa. A circuit for an i.f. strip using the new frame -grid 4190V variable -mu EF183 is shown. It consists of a first i.f. stage which is common to sound and vision, followed by a second i.f. stage in each channel. Apart from component value changes, the only difference from PudO normal practice is the use off 10% neutralising capaci- RFC tors. When the strip is used with the frame -grid PCC89 ¡E1391 in a cascode r!, stage and the conventional PCF80 mixer, adequate gain is achieved for use in fringe areas 1 4pF without the addition of a further vision i.f. stage. For Band III reception the maximum sensitivity required of a fringe area receiver is 20µV for a picture of normal 820" contrast level. Even for signals weaker than 20µV a receiver of this sensitivity will give the best picture possible. (A higher sensitivity will produce excessive noise on the screen.) The Band I requirement is slightly less stringent and will in practice be easily met in a receiver which satisfies the requirements for Band III. 1004 ^+ ^ With the strip shown, and with the PCC89 and PCF80 rF in the r.f. and mixer stages, 11µV at the aerial will 1.0kn 1.0 mn provide 2.OV of video. A typical receiver with a con- ventional valve line -up (PCC84, PCF80, EF85 first i.f., EF80 sound i.f., EF80 vision i.f.) requires 63µV. Thus the to take the conventional EF80, with the EF183 retained conventional receiver fails to cover the required signal in the first i.f. stage. With this new line -up, a 2.0V video range for fringe areas, and it would need another i.f. output is obtained with 9µV on Band III and 5µV on stage. The frame -grid receiver, on the other hand, covers Band I. the range and has an adequate margin for production The circuit shown provides adequate a.g.c. on sound, and tolerances. approximately 80dB vision gain control without serious will be It noticed that the conventional PCF80 has been cross- modulation. Comparable performance is obtained retained in the mixer stage. If the frame -grid PCF86 with the PCF86 variant. Both versions are notably 0is substituted, then the second i.f. stages can be modified superior to conventional line -ups. M U L L A R D HOUSE, T O R R I N G T O N PLACE, L O N D O N, W . C. 1 MVM 471 www.americanradiohistory.com NOVEMBER 1959 World Vol. 65 No. 10 Wireless National Science to get SCIENCE is a method, a habit of thought which policy is to leave the various Departments facility is practised not only spontaneously and individ- on with their work, but to provide greater and to ually for its own sake, as a rewarding personal for the removal of possible antagonisms bene- activity, but collectively and deliberately as a increase co- operation where this would be in solving efficiently the prob- ficial. means to an end must lems of technology and economics. Pure science It is unfortunate, but inevitable, that there time infra- and supra -national in the always be a conflict of interest as far as the claims is at the same In our sense that original thought is the work of indivi- of civil and military science are concerned. have an affinity of interest with other own field this shows itself in the arguments over duals who the workers in the same field regardless of race or the allocation of radio frequencies. Whereas Applied science, on the other hand, has claims of broadcasting and civil communications creed. those of a military and market value and is consequently, must be justified in the greatest detail, and quite properly, a subject of political interest. the fighting services are safe from public criticism Under the pressures of expediency and in behind the wall of " security." As we have said where the well -being of the com- before, these conflicts can be resolved only by a circumstances entrusted munity as a whole is involved the Government minister of Cabinet rank who can be money and accepted responsibility for with the full facts on either side. In this respect has voted be of all kinds, from agriculture to the powers of the Minister for Science will scientific work Presi- energy and from roads to radio. While similar to those which he held as the Lord atomic will be this work is necessarily secret, much that dent of the Council. We hope that they some of of more widely known is lost to view be- exercised and that some means may be found should be are hoarding cause it is considered either too esoteric or too allaying suspicions that the military to catch the popular fancy. At times like wavebands as they sometimes do land. dull for Science the present when satellites and moon rockets serve The main functions of the Minister man in the street conscious of the will be to listen sympathetically and to talk per- to make the and, scientific effort throughout the world suasively, to release tensions and to reassure, vast scale of to recom- it is natural that he should want to know what if any real malfunction is diagnosed, this country are doing to keep pace with mend treatment. The choice of Lord Hailsham we in Although the march of events. for this post is, we think, a good one. questions of detail can be put to the not a qualified scientist he has already shown him- Although to be en Ministers responsible for the separate depart- self, as Lord President of the Council, will con- is not always easy to find where the rapport with the scientific world. He ments, it the responsibility lies because the labyrinth of Govern- tinue to have first call on the services of so complex that many of its Advisory Council on Scientific Policy and he will ment Science is the obscure, even to those with some know- maintain contacts with the Royal Society, byways are and the of its main structure. The feeling is wide- Universities, the Ministry of Education ledge said that one spread that not enough is known about the deploy- Research Councils. Already he has resources and effort in the scien- of his first tasks will be to forge closer links ment of national the and this was no doubt partly the reason between Government research stations and tific sphere, to gain the inclusion in the Conservative Party's elec- Universities in the belief that both stand for more intimate tion manifesto of a promise to appoint a Minister in prestige and effectiveness by responsible to the Cabinet for the association. for Science the portents for overall promotion of scientific and technological Not since the Restoration have British science been more favourable, and in Lord development. to we think, the new Government has Hailsham this country has found the man match Wisely, his forth- pressures to form a whole new Ministry the hour. His long political experience, resisted in science and scientists of Science.