AMATEUR WIRELESS, APRIL 6, 1923 "BRITAIN'S FAVOURITE THREE -1929 MODEL Every Azsr i I Thursday() Vol. XIV.No. 356 Saturday, April 6, 1929 RITA1N'S AVOURITE Registered at the G.P.O. as a Nel...3-ttr t*, 3929 matter Whet, APRIL 6, l' 11 1S ? 9041014ofnatne is there adifference isonly Actuallyis aperfected there Ventone. Niullard that and. theVentonewhole thinli.valve tor the use ini0,titeatade world, with, its Sounap iathe it. in. byNkullard, increaseof betWeedifiereaeeonly behind llardin anan state alltheinade one tl-t artareptaation resultsafurther areeceiveradding, -valve. tradition. practiceogar by different, and stateobtainedsopa-powertobe valve "(beery that just all aown theoutputtoealaloviag VentooeAfterofits equal itthe veil volume call anative the araplification&alit perfortoancedeserve for its LS -We superiordoes but With ot its itself nosnob,inhand iaeldeatalki by is hand aclass Pentane beatbecauseis in toWorlz t Mulfordit pefers N.B.results brothers. best P, MullaYd IsarALOE 0.SAS The Mallard Wireless Service Co, Ltd., MullardHouse, Denmark Street, London, W.C.Z. Advertisers Appreciate Mention of "A.W." with Your Order APRIL 6, 1929 513 amour Wtraluj. THE AINvict 1 it I EXPEpts, LEWCOS COI LS ENGINEERING PRECISION... Engineering Precision has once again resulted in J.B. Condensers being chosen for yet another Star Circuit-in fact, it's no easy matter to -day to find a really high-class set which does not include these precision instruments. This time J.B. Logarithmic Condensers (Plain Type), are used in " Britain's Favourite Three " De Luxe, as described in this issue of " Amateur Wireless." These Condensers are the last word in ULTRA -SHORT- high-classdesign,possessinggreat SIX -PIN COILS WAVE COIL mechanical strength combined with the highest possible electrical efficiency. An important feature of this model is the Variable Friction Brake, by means of USE THEM which the turning tension of the rotor may be varied to suit individual require- IN ments, while at the same time the move- ment of this condenser is extraordinarily " BRITAIN'S smooth. FAVOURITE Prices, complete, 4 in. Bakelite Dial :- .0005 . 11/6 .0003 FIXED POTENTIOMETER . 10/6 THREE" .00025 10/- .00015 10/ RADIO PRODUCTS THE LONDON ELECTRIC WIRE COMPANY AND SMITHS, LIMITED CHURCH ROAD, LEYTON, LONDON, E.10 Telephone : Telegrams: Waltharnstow 2531 "Lewcos, Phons. London." INSTRUMENTS LEWCOS RADIO PRODUCTS FOR Trade Coanter and Calle Sales : BETTER RECEPTION. 7, PLAYHOUSE YARD, GOLDEN LANE, E.C.1 Advt. of Jackson Brothers , 72, St. Moms' Street, London, Telephone: flop. 1.637. To Ensure Speedy Delit4ry, Mention `.`A.W." to Advertisers APRIL 6, 1929 entatew Wire65.3 514 Imported Dty Batteries of all descriptionsarekeeping 5000 BRITISH WORKPEOPLEON THE DOLE Helpyourfellow Countrymen andwomenby BUYING BRITISH EVER READY, BRITAINS BESTBATTERIES Giveyousecurity guaranteed service DRYfor CELLS Bells.Telephones & valueformoney etc. REFILL BATTERIES for Lamps &To,c63 EVE' WE- Y sttet HIGH TENSION BATTERIES for Wireless Yourincreased support will enable us to reduce working costs and give still better service. Advt.of The Ever Ready Co. (G.B.), Ltd., Hercides Place, London, N.7. You will Help Yourself and Help Us by Mentioning "A.W." to Advertisers St 5 0,-,,-.,,,-,,,,,,--),,,,,--..-,,,,,,.,-,,-,--,,,,,,,--,,,,,,t.e73..c_<-.:Itc.-...--1,t,_..-,)-1c,-)Iate7)w-1--)c),--4te7ir.v.._>ttel:1 C APRIL 6, 1929 No. 356,Vol. XIV C S C S 5 C 5 Ontatzur ue , 5 and Radiovision 5 The Leading Radio Weekly for the Constructor, Listener and Experimenter § = ---Editor : BERNARD E. JONES Technical Editor :J. H. REYNER, B.Sc., A.M.LE.E. :: Research Consultant: W. JAMES :: Assistant Editor: H. CORBISHLEY § ricete7)---)clec7.1e-lca-)t,:7)tc)t.4:7)e)--7-1-. t.')r--)t.--)t71wle-.)t--1t.:ItIte7Ite7).+ctoit%)t-oc,tclte%)t-v.,.ett7)c-)t4.2)r---7it.&>0.4n.,.)0 Is There Jamming ?-Fultograph Filmed !-" Hot" News-Exit Jeffrey- The General-Don't Swear !-Next Week Is There Jamming ?-Why is it that 5 \ X on April 7, when General Higgins, when thinking of towns with "broad- the new leader of the Army, will conduct casters in every block" one always starts a service to be relayed from the Congress with New York? Apparently the U.S. has Hall, Clapto,n, London, E. not the monopoly of jamming, for the Don't Swear!-Has it ever occurred evening paper in Toronto, Ontario, gives to you when listening to the running com- every day the programme of five stations mentaries, such as the. football broadcasts in Toronto itself, nine stations elsewhere and the Boat Race relay, what a tempta- in Canada, together with a schedule of the tion it is for the commentator to make programmes of seventy stations in the ejaculations which the microphone and United States. some of the millions of listeners might not Fultograph Filmed!-A film entitled like?After all we are only human, and :The FultographStoryhas been incor- it is very natural that a keen sport enthu- porated in Pathe Pictorial No. 571. This siast should forcibly and fiercely vent his has been booked by over, a thousand feelings in ungentlemanly style when, say, 'cinemas throughout the country, and is a good pass is dropped !The B.B.C. makes expected to be showing in most districts thoughtful provision for this, often, by ,within a week.Incidentally, perhaps all placing a large notice, "Don't Swear !" in broadcastpictureenthusiastsarenot frontoftherunningcommentator's 'aware of the fact that experimental tests "mike." are being made at the Royal Airship A New Rela y!-A clever skit is to be [Works at Carclington in the course of Before its time-a spark transmitter and receiver given on April 9, under the fascinating in use, in 1902, at Streatham Fire Station. A ,which weather maps are beingtrans- telephone is now used. title of "A relay from the National Radio mitted by the Fultograph system and Station in Erewhonia."This programme, received in a number of places in theregretted by alllisteners.Nevertheless,which consists of typical scenes from British south of England. There is obviously ahe should be able to do some good worklife, is said to be founded on a study of [big future for this sphere of picture broad-for the "talkie" people, and they are cer-B.B.C. methods made by a Northern casting. tain to be congratulated on the initiativeErewhonian representative during a visit " Hot" News-And, while on thethey show in getting good men like JeffreytoLondon! subject of Fultographs, a word of praisewith ready-made experience. " The Proms."-The B.B.C. has de- 'must be given to the Wireless Pictures The Genera/-A broadcast which willcided to hold an eight weeks' season of people for the way in which they arebe of particular interest to all members ofPromenade concerts again this year, start- starting to fulfil their promise about givingthe Salvation Army is that from 2L0 anding on Saturday, August 17, and conclud- listeners real news pictures. Boat -tic471cce7iciw-icar.e7o.ce7icace,lece7ne7e.e7lote7i0ing on October12.Sir Henry race photographs were broadcast § PRINCIPAL CONTENTS Page §Wood will be the conductor.The within an hour and a half of the5 " Proms."seriesisone much race, you may remember, and even- Current Topics .. 515 appreciated by listeners-" high," § ing papers contained pictures of the 14 Audiences at Once.. 516 " mezzo " and " low -brow." Grand National wired, via Fulto-5 Improving Your Portable Next Week-So many people graph, from Aintree. § Electrical Recording at Home.. 551187 1like reasonably simple and self-con- Exit Jeffrey-A loss to broad -5 On Your Wavelength.. 519 5tained sets, particularly if electric - 'casting and a gain to "talkies" is§ Cutting Out Needle Scratch.. 523 5light mains can be used, that the WIRLLESS Mr. R. E. Jeffrey, who, we learn, ci My Wireless Den .. 524 5Am ATEUR Technic al has resigned from the staff of the§ Points About Exponential Horns 525 §Staff is sure next week's set will be B.B.C. in order to take charge of a winner. It is a "simplicity" two- the sound production department5 Without Fear or Favour 527 §valver, working entirely from A.C. of British International Pictures,§ Britain's Favourite Three Up-to-date 528 §mains and using the new directly - Ltd.Mr. Jeffrey has, of course,§ The "Arcadian Portable " Afield 531 heated Valves and a simple rectifier been associated with broadcaSting "A:W." Tests of Apparatus 532 §for H.T. No H.T. batteries to run § for the past six years, and the fact §downoraccumulators § Radiograms 534 to"go of his leaving the sphere in which Our Information Bureau 537 5phut" just when there is a good he is at present best known will beClcev.lcoicacatoitoice:macatatacac,at&vlwIcioie,.7)05 Programme to be beard (imam WireiT 516 APRIL 6, 1929 I AUDIENCES I AT ONCE ! Political Broadcasts Made Possible by Wireless By An " A.W. " CORRESPONDENT and other sounds similar to atmosphericsgrids are connected together to the second- being introduced.Now, it is a curiousary of a special to to i Marconi Ideal trans- fact that noises one would hardly noticeformer, but the output circuits are inde- when listening to speech on headphonespendent. It is therefore possible to control assume serious proportions when the wholethe input to individual lines and a fault on is raised to loud -speaker level.This mayany one line will not affect the others. A easily be confirmed on any wireless set.listening point and volume control are also Unless,therefore,the inputisstrongfitted to each circuit. enough to ensure an output intensity well above that of any interference, the amplifiedTwenty-six Trunk Lines! results are rather like those obtained when The final unit at the trunsmitting end RECENTLY I described in AMATEURtrying to receive a distant station duringwas a thirteen -way change -over and moni- WIRELESS how land -lines were useda thunderstorm toring panel from which radiated twenty- for a giant political" S.B." of speeches from Repeaters solve the problem, as withsix trunk lines, each of the thirteen circuits Newcastle simultaneously to a number ofthem we are able to start with a moderatethus being duplicated again.The spare other towns.