Modern-Wireless-1933
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October, 1933 MODERN WIRELES i Vol. XX. No. 82.MODERNWIRELESS. OCTOBER, 1933. Page Page Editorial . ..279 What Are Waves? 331 Introducing the K4 .. ..280 On the Test Bench 333 The Kendall Step System.. Scophony Television 336 The K4 Circuit .. 228398 Questions Answered . 338 How to Build the K4 . 295 The Radio Newspaper .. 340 Operating the K4 306 The Pick-up in Practice 342 The Performance of the K4 ..310 Round the World of Wireless 344 An Invisible Ray Burglar Alarm ..312 Reflections of a Radiotic 345 The Mystery Station of Switzerland 313 Kendall's Corner.. 348 Spotlights on the Programmes 315 Trouble Tracking 351 Long -Distance Mistakes .. ..317 " " Record Review.. 352 The Future of German Broadcasting 318 At Your Service .. Real Gramophone Tone Control ..321 HintsandTipsforthe My Broadcasting Diary .. ..323 Handyman .. 356 Faults I Have Found.. ..325 " Death at Broadcasting House " 358 Aerial Circuit Selectivity.. ..327 China Takes the Air .... 381 Round the Turntable.. ..330 Radio Notes and News of the Month384 As some of the arrangements and specialties described in this Journal may be the subjects of Letters Patent the amateur and trader would be well advi ed to obtain permission of the patentees to use the patents before doing so. Edited by NORMAN EDWARDS. Technical Editor: G. V. DOWDING, Associate I.E.E. Radio Consultant -in -Chief :P. P. ECKERSLEY, M.I.E.E. Scientific Adviser: J. H. T. ROBERTS, D.Sc., F.Inst.P. 100testswith8turns The of the knob... Sherlock Holmes of Radio No other single Radio testing is revolutionised by the Pifco instrument in ROTAMETER. The key to its simplicity lies the world makes in the octagonal knob with its eight marked alltestsmore faces -" The Sign of Eight." The symbols on easilythan the these faces give a range sufficienttotest Pilco ROTA - everythinginradio.Just turn the knob ME TER. Any component or circuit for test desired, connect the part or circuit can be tested quickly and surely. Makes up to the ROTAMETER, and the result is 100 tests. BRITISH MANUFACTURE there in the window of the instrument. The Pifco ROTAMETER tests everything. RANGES: Even itself !The BATTERY TEST registers ROTAMETER 1.-0-8 volts.For low-tension voltage the voltage of the three No. 495 radiometer Patents Penchn9 test. cells inside the ROTAMETER. Another point 2.-0-30 volts.For grid -bias voltage about this wonderful instrument is the Safety 0-.E13iV2o1htstRao-n.Voes test. Fuse which safeguards it against damage by 0- 30 Volts 3.--0-250 volts. For high-tension voltage careless handling. 0- 100 A 0-250 Salts 0-250 test. BatteryTest for." A 4.-BATTERY TEST. Get your radio dealer to demonstrate the Pifco Fr .a ResistATest 5.-0-20 M.A. For individual valve test. ROTAMETER to -day.If any difficulty, write directtoPIFCO,LTD.,HighStreet, ro,Ristane;Z:trt 'n1,01<lor. 6.-0-100 M.A.1For testing current taken MANCHESTER, or150Charing Cross Road, 7.-0-250 M.A.by total valves in set. ,5on top. 8.-FILAMENT AND RESISTANCE London, W.C.2. TEST (4,000 ohms).For D.C. and rectified A.C. PIFCO PRICE ROTAMETER TO .3 MODERN WIRELESS October, 1933 06 AMONG TABLE RADIO SETS The Superhet Concert Seven combines the very latest improve- qments in radio science, such as delayed automatic volume control (which eliminates fading of long-distance programmes), static suppressor (which prevents the amplification of any signal in the BECAUSE " mush "), and real adjacent channel selectivity.It provides not only a range of stations to satisfy the inveterate station hunter, but also a tone to please the most sensitive musical ear. IT IS A SUPERHET To prove its supremacy needs but a fractional turn of. the tuning SEVEN qknob-to prove its supremacy as a musical instrument, just listen ! Here is the realism of the Concert Hall itself-a tone that is true IT HAS CONCERT to life 1The technically minded will find further details to TONE & VOLUME interest them in the brief specification below. But besides being good to hear, the set is also remarkably good IT HAS DELAYED qto look at.Altogether, an instrument you will be pleased to listen to, pleased to look at, and, since itis made by " His AUTOMATIC VOL- Masters' Voice," proud to own.Price 22 Gns. (or by Hire UME CONTROL Purchase). IT HAS A SPECIAL BRIEF STATIC SPECIFICATION : Superhet Concert SUPPRESSOR Seven IT HAS ADJACENT Model 467 Seven - valve (inc. CHANNEL rectifier) superheter- odyne circuit SELECTIVITY Marconi valves. Automatic Volume Control. Illuminated Scale with wave- lengths and station and names.Duplex tone control. Movingcoil, mains -excitedloud- speaker.Sockets for gramophone pick-up. BECAUSE Power to operate three additionalloud- speakers. Height - 1 ft. 7} ins. IT IS BUILT BY Ikidth -1 ft. 51 ins. Depth-- n ins "HIS MASTER'S VOICE" TRUE8TO0LIFE RADIO & RADIO GRAMOPHONES The Gramophone Co., Ltd., 98-108 Clerkenwell Road, London, E.C. Price does not app(y I.F.S.) October, 1933 MODERN WIRELESS 1()IVIPPNm,ifite Ac kk%-\ Vol. XX. No. 82. viviiitt0/4BRITAIN'S LEADING RADIO MAGAZINE October, 1933 Two Outstanding Contributions-The K4 and " Death at Broadcasting House." \ this special issue of MODERN WIRELESS we are pleased builders would feel that the set was not beyond his to present to our readers two features of outstanding powers. importance, namely, the exclusive contribution by It was doubted at first whether such a method could Mr. G. P. Kendall or the construction of his latest and be adopted in practice, but we think readers will agree mostingeniousreceiver-The K4 ;and,secondly, that Mr. Kendall has achieved his ambition when they the opening instalment of a new and thrilling serial read the following pages giving the fullest possible details story, " Death at Broadcasting House," which has been for the construction of his latest and finest receiver.For specially written for readers of this magazine by two there is no doubt that not only are the technical merits very well-known B.B.C. personalities-Mr. Val Gielgud, of this receiver obvious to the initiated, but as the article is the Director of Dramatic Productions, and Mr. Eric read they become increasingly easy to follow and to Maschwitz (under the nom -de -plume of Holt Marvell), understand, even for the veriest tyro. the newly -appointed Director of Variety. We feelconfident that in presenting the K4 we are offering readers of MODERN WIRELESS a chance to The Finest Ever Published build a receiver which, in every sense of the phrase, will THESE two features alone, we never let them down." think, go a very long way to making this issueof Our New Serial Story MODERN WIRELESS oneofthe WE shouldverymuch finest ever published.To begin welcome letters from with, Mr. Kendall's K4 isun- readers concerning our doubtedly goingtoprovethe new innovation in radio jour- outstanding 4-valver of the year. nalism-the introductionofa The receiver has two very distinct radio serial story. In the past we andimportantnovelties - the have from time to time pub- Step System of construction and lished radio short stories,but the tone -levelling principle. we think we are right in saying Whendiscussingwith Mr. that this is the first time any Kendallthevariouspossible wirelessmagazine hasever methods ofpresenting the K4 offered to its readers a full-length receiver toreadersof MODERN novel in serial form by two very WIRELESS, Mr. Kendall suggested well-known iiauthors.We hope that he should not only deal with you will enjoy the story-and the problems arising out of his we hope, as all Editors and all new set in a way which would authors must-that it will keep make animmediate appeal you in suspense, and that not to the more technically -minded until the very last instalment reader of this journal, but should will you guess the name of the at the same time explain-when miscreant who brought " Death necessary at length, and always to Broadcasting House." At with clarity of detail - the any rate, although the chances actualdetailedprocess of are you will suspect most of the constructing the K4 thateven characters at one time or another, the most inexperiencedofset - we promise you a big surprise ! The Inventorof the K4, G. P. KENDALL, B.Sc. and the Step System fully described in this issue. 279 0.60 K 4BLUEPRINT CONSTRUCTION CHART TUNING DIAL Iti4.5 ;Yci"Ere TUNING DIAL C WE AB EAC: TERM 5POINT J ON- O Swircn TUN/NG IPEACTION CONDENSER 7Cl/V/AIG 000541F0 CONDENSER CONOEIVSER J -O003MFo .0005 /WO C LIPLANGa4 1 S Nor I SED 3 2 8v IBit AERIAL I 12 VI CO/L L3 3 I 4'3 aAss 0 reur CHOKE 000.5 Nor$ OsEog Au ',lox Av A NT A0 01 &/ Gwr-A/va CE II SCREEN fpBNeR/D BN GRID PLAT' BG "er Y Ant COMPENSATING To ANODE OF Ax F TRANSFORMER WANDER ICLCI6 BP EARTHIEA FUSE AERIAL BR NT- NT.f/ L TIL LT- N T74-4 TUN/NG DIAL e I 7Z//W/Y1.3 DA 44. .- mem ..... .3 POINT awe li OFF ,./ aims= E.o.C. = ON- TERM. 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