S g Experimenter's Licence for The Home-made Set ( p. 591)

No. 26 SATURDAY, DECEMBER 2, 1922 Price 3d.

Regular Regular Features Features RADIOGRAMS TELEPHONY TRANSMISSIONS

111 ON YOUR WAVE- LENGTH CLUB EVENTS

la RI if 6c1 3

INFORMATION LETTERS BUREAU Photograph of a Single -circuit One -valve Set constructed by ETC.ETC. Mr. A. W. Owen, of Walthamstow si 111 SPECIAL ARTICLES Atmospherics or Statics Amateur Transmissions and the A Basket -coil Type Tuner G.P.O. Shall We Ever See by Wireless ? A Novel Utility Aerial Telephone Winding All About the Valve Loose -coupler Device Rectifying Panels for Unit Set InterferencePrevention emataitWttviess 582 DECEMBER 2, 1922 (1VIITCHELFONES ECONOMICELECTRICLTD. Are not a spasmodic production to meet A I a sudden demand, but have been on the

I-1 Have YOU tried the market for over three months, and during this period 27,000 have been distributed " XTRAUDION " VALVE ? to thetrade, and consequently we have the latest and best development of not been able to offer them direct to the

retail buyer. the 3 Electrode Valve. RECTIFIES, OSCILLATES 1,000per week are now available, and we announce AMPLIFIES Its Mechanical Construction DELIVERY FROM STOCK makes it a stronger and more lasting Youpostyourorder,orcallatour valve than any other. premises and get them at once.Think

The Filament consumes well under what this means to you-you, perhaps, who half - an - amp. at 4 volts.Anode have been waiting and are stillwaiting.

Potential, 50 volts. Standard resistance 4,000 ohms, double headgear with Its Amplifying Properties are double headstraps,comfortable,highlyefficient, wonderful and its freedom from noises and foolproof a revelation. Send for Descriptive Leaflet. 25/- per pair:

15/- 15/- Special Terms to Traders and deliveries that will surprise you, U PRICE PRICE PATENTS PENQINC MITCHELLS Electrical & Wireless Ltd.; We publish the most complete Wireless Postal Address: McDermott Road, Peckham, S.E.15. Catalogue obtainabie.36 pages, profusely Retail Address: 188, Rye Lane, Peckham, S.E.15. illustrated, and many usefulcircuitsfor Head (Vice 10, FITZROY experimental work. Mailed to any address 'Phones: New Cross 1540,1541. SQUARE, LONDON, W.I. on receipt of four penny stamps.

Showrooms Telephone : LI)anch Showrooms 6. Works : cGREATBRITAIN'S GREATEST WIRELESS STORE-4(1) 303, EUSTON ROAD, N.W.I. MUSEUM 1055 TWICKENHAM

ofInterest to Amateurs "PERRYPHONES" n Auction HEAD SETS FOR WIRELESS TELEPHONY Included in this important Sale of 4,000 ohms.! Ex -Government Wireless Apparatus 21 Every SetGuaranteed. Beautifully there will be a large number of finished, highly sensitive, detachable receivers, eminent!y suited for purchase SMALL LOTSby WirelessExperimenters IMMEDIATE DELIVERY THE TRADE will also have anexcellent opportunity of securing: Illustrated NVireless Catalogue now New Mark III Tuners,Mark III C.W. Trans- ready, post free, 3d. mitters and Receivers. B. Mark II2 -Valve Detector Amplifiers, 50 Watt Spark Trench THE JEARY ELECTRICAL CO., LTD., Sets for Receiving and Transmitting, 8, LAMBETH HILL, and 97, QUEEN VICTORIA ST., C. Mark III 3 -Valve Amplifiers (low frequency) in new LONDON, E.C.4. condition. Ind at Glasgow, Birmingham, etc. Brown's Head Telephones, Reed Type, 120 to 8,000 ohms in new condition. Valve Boxes, Teak Instrument Cases,a quantity of 13ft.Masts, '4181111111111111111111111111111111111111111111111111111111111111111111111111111111111818111181111111111111111111111111111111W and a large quantity of Miscellaneous WIRELESS GEAR. COMPLETE and EFFICIENT AERIAL SETS LTil = -F. STEVENS' AUCTION ROOMS --#: For Single Wire Aerial For Double Wire Aerial E= (Established 1760) 110 feet 7122s Copper Wire I E L--- 100 feet 7122s Copper Wire= = 2 Shell PatternInsulators, 4 Shell Pattern Insulators -.7.-7.. Will sell the above by Auction = which guarantee High 2 Hard Wood Spreaders, 174. :: attheir Great Rooms :: = Insulation 6 feet long E-- - 2 Wall Fixtures 2 Wall Fixtures = = or or 38, King Street, Covent Garden, E. 1 Wall Fixture and 1 Mast 1 Wall Fixture and 1 Mast g W .C.2. =-- WEDNESDAY, December 6th, 1922, E.= PulleyPulley E7.-. 10/complete 16/6 complete =E At 12.30 o'clock precisely _=_ =E Delivered Free' front Stock. Cash with Order = = Please state clearly whether you require 2 Wall Fixtures = OnView: Monday, 4th December, from 12.30 to 5.30, Tuesday H- or IWall Fixture and l Mast Pulley .; from 9.30 to 5.30, and on morning of sale from 9.30 to 12 o'clock = = =. = THE SOUTH WESTERNWIRELESS SUPPLIES CO. ;....-=-. CATALOGUES ON APPLICATION. 382a, Merton Road, - Southfields, - London, S.W. Telephone -1824 GERRARD. Telegrams-" Aces, RAND, T. ',CON." .-,- = RINNEIN111111i TI111111111111111111111111111111111111 11111111H1111111111111111111111111111111111111111111M11111111111111111111111111111111111Ti 5 63

and Etzctrics No. 26 December 2, 1922 ATMOSPHERICS OR STATICS OF late we have had several pessi- between.the dots and dashes, making mistsinour midst who have The elimination of atmospherics or statics is italmost impossible todistinguish beenpreachingdisaster bythe one of the most pressing needs of modern them. mighty -hand of static..They tell us wireless. This article explains the effects So faraswireless telephonyis thatwhenthebigbroadcasting andgivessome simplehintsthatmay concerned, however, I do not think stations begin on their long -delayed provide a key to the problem. that static will be found nearly .as programmes we shall begin tosee serious.In the first place wireless how undeveloped the science is as telephony is conducted by means of yet. They tell us to wait until we arepassage of the charge is recorded in thecontinuous waves, and where theseare listening -in on one of our favourite pieces,telephone receivers.These static chargesused in the ether we get sharp tuning, and in the midst of our enjoyment are sud-are so broad and cover so many differentwhich is in itself extremely helpful. denly enraged by a discordant jargon ofwave -lengths that they penetrate almost all Then again, we are dealing now with sound-static interference again. turning adjustments, this being, perhaps,voice and music sounds, and these vary Most probably you have met one of thesetheir most annoying characteristic. in pitch and amplitude, so that the hearer pessimists.He gives one the impression The peculiar thing about staticis thatdoes not have to concentrate on one pitch that our receiving sets will be useless untilitis most prevalent in tropical countries.and pick up dots and dashes.I believe some method is found of eliminating theIn northern latitudes it 'is most prevalentthat with careful tuning the voices and disastrous static.In fact, static is the bigin summer, and alWays worse during themusic will ride clear above the static, but bogy of the wireless world. night than during the daytime.Its effectof course, the tuning must be very dis- But up to the present we have not suf-upon the telephones ranges from harsh,criminate, and that only comes with ex- fered so badly from it,I think.Let usrasping soundsto mushy squeaks, andperience. see what static is and how it behaves, andwhen itisreally bad it continues unin- perhaps we may pick up a hint or two soterruptedly.Such are the conditions ofSome Hints that we may be able to combat its effects.static. Here are a few suggestions for use where static comes in very badly. Haw Static Behaves If you are using a two- or First we must realise that three -stage amplification in broadcastingisnot a new connectionwith a loud thing; the only new thing is speaker, forgo that pleasure the public. interest which is for a little while and cut now being taken in it. Ever out, the whole lot.By lis- sincethe development of tening -indirectfromthe the wireless telephone to a detector you will necessarily point of good performance, sacrificesomedegreeof amateurs have been broad- volume of sound, but you casting to one another, and willgainmuchinthe they have done it very well. clarity of the signals from Static has not seriously in- the headphones. Remember convenienced them so far. that the amplifying valves. The best way to explain extend their power toall static simplyisthatitis currents that come in, and lightning in the making.It thatstatic, being stronger consists of accumulated than theradio -frequencies, charges of electricity which isamplifiedto a greater arestoredintheatmo- volumethanthesignal. sphere, not large enough in sounds. capacity to break down the Another hint is to reduce, airresistance andfinda the amount of current pass-. Photograph of Four -valve Set of the Small Cabinet Type. Ix -ayto theearth. These ing through the valve fila-; Charges are stored up just (Telephone Manufacturing Co., Ltd.) ments to the lowest possible like charges on the plates amount consistent with the of a condenser, and; like the result of static, because the latter, some of the chargeleaksacross Static and Telegraph.), more current passed through the valve the the dielectric, or air. To wireless telegraphystaticoffersa more the static is increased in intensity as InthecaseOf static,thisleakage x-eryserious opposition.!The sounds ofcompared to the music. takes place along the aerials of wireless.'thecodeareveryI constant,and, this Above ,all, make all tuning. adjustment stations wherever they -are' erected, and theallows the atmospheric interference to getcarefully and very slowly. A. J. B. mateur WirettS5 584 DECEMBER 2,1922

A Neat Efficient Tuner A Compact Tuner of the Basket -coil Type ci

THE followingisa description of ahalf inches for wave -lengths from 600 tonear itspin,as shown in Fig.5. The tuner of a neat and compact type andr,roo metres.The holders are made fromreaction coil consists of a small slab coil remarkable efficiency. ebonite in. thick, and are 3 in. long bymounted in the same manner as the basket The apparatus is mounted on an ebonite1% in. wide (see Fig. 3).Each. has a slotcoils, and is sufficiently small to prevent the panel 9 in. long by 5 in. wide and in. 743-ff in.wide cut lengthwise through theset from oscillating, while large enough to thick (see Fig.1). This is screwed on tothickness of the ebonite (see Fig. 4).Themagnifythetelephonyorsignalscon- a mahogany box of the same size as theslot has a depth equal to the radius of the siderably.The two-wayswitchatthe panel and 4in.deep made from k -in.coil intended for it, and is made by firsthack of the panel reverses the direction of wood. cutting two slots 3T in. apart with a finethe current flowing in the reaction.This Theaerialtuningcondenserofa stiff -back saw and then cutting out thehas been found very useful, particularly capacity of .00r microfarad and a smallebonite in between with .afret -saw.Thewhen using high -frequency amplification three -plate vernier condenser connected incoil fits tightly in the slot in its holder.withtheplug-intypeoftransformers,

IND. REACT.

111W SOLDERED EXTRA REACT PHoN e

GRID

EXTRA .710W. IND. e Fig. 2.-Coil Former. s Fig. 6.-Diagram of Connections. `theseillustrations show the details of a remarkably efficient apparatus of simple construction 11 Fig. 5 (above).-Detail of Holder for Re- action Coil.

F;g. 1 (left). - The Fig. 3.-Coil Holder with Coil in Position. Complete Tuning Unit.

Fig. 4.-Side View of Coil Holder. Fig. 1 parallel with the larger one are mountedThe holdersareeachfittedwithtwowhose windings are not always in the same on the panel.The two-way switch on theordinary valve legsrin. apart, and thesedirection. front of the panel enables these condensersplug into valve sockets on the back of the The four terminals on theleft of the to be placed in series with the aerial fortuner. panel are to enable an ordinary solenoid short wave -lengths, say, 18o metres to 500 The sockets are r in.apart and aretype of inductance coil with reaction to be metres, or in parallel with the inductancemounted on a piece of ebonite 1/4. in. thickused for longer wave -lengths than r,000 for higher wave -lengths. and 2 in. long by % in. wide.This lattermetres, in which case the short-wave coil Theactualtuningcoilsandtheiris screwed on to the back of the mahoganyandreactionareremovedfromtheir holders are of rather novel design.Theybox.A similar piece of ebonite with twoholders.An alternative would be to wind consistof basketcoils wound with 26 -valve sockets x in. apart is mounted by itsthe basket coils with more turns of finer gauge enamelled copper wire on thin card-side on an ordinary brass hinge, which is wire,butthiswouldmeanlossof boardformers oftheshape shown infastened on to the box.This holds theefficiency. Fig. 2.These are well dried, shellacked,reaction coil and is capable of swinging Fig. 6 shows the internal connections and then baked. A depth of wire of halfthrough an angle of 90 deg. (see Fig.5). of the tuner. an inch is suitable for wave -lengths fromA long handle made out of a piece of This tuner has been found to give excel- 18o to 30o metres, three-quartersof anright-angledstiffbrasswirewithanlentresultswithtelephony,itschief inch from 300 to 40o metres, one inch fromebonite knob onone.end is soldered on toadvantage being the ease with which any 400 to 600 metres, and about one and athe top' movable part of the brass hinge,station can be tuned in. H. B. DECEMBER 2,1922 585 ettint,,,r Wtrdess however,remains,andindeeditsuse seems essential in considering any attempt todealwith such alarge number of A SimpleDevice Television. VI signals. Shall We Ever See by Synchronism for Operating the The use of wireless, although practic- Wireless(conclusion) ally overcoming one difficulty, introduces Loose -coupler another of even greater importance.This is the question of synchronism.In ordi- The Application of Wireless to Televisionnary photo -telegraphy, where no time limit THE accompanying diagram shows a WITH the problem of television stillis set for the reproduction of the secondary device for operating the secondary coil in the experimental stages, and withpictures, the limit of error in synchronismof a loose -coupler,such as that of the no system sufficiently developed to be cap-requires to be at leastI: soo in order toshort-wave set described in the Handbook able of working successfully over even aobtain resultsatallsuitableforpubli- short length of metallic circuit, any sug-cation.Even where the two stations are gestion regarding wireless television may,connected by a metallic circuit, maintain- TOPor Box immr perhaps, be considered mere speculation.ing this degree of accuracy over a pro- WAWA' ',1"//0000/ This, however, is not the case, for eventracted period is no easy matter. A limit Alik with the introduction of a praCtical system I: Soo of error in synchronism as high as BRASS SPINDLE. of television there arc certain features in-orr : t,000 will at least be necessary in herent in all telegraph and telephone linesthe case of television, but even this degree PRIMARY that would prevent transmission over anycould no doubt be obtained by the use of COIL but exceedingly short distances. alternating currents in the manner already explained. Woos SECONDARY SPINDLE ,Possible Speed COIL The rateat which separate telegraphThe Future signals can be transmittedisdependent In any wireless system of transmission TOPVIEW upon the resistance and capacity of thethe difficulty arises from the fact that the Device for Operating tat, Loos[ circuit. Over averyshortlengthof two stations have to run independently, the Loose -coupler. linewhere thecapacity andresistancethe one link that at present makes syn- effects are slight,signals can be trans-chronism possible-the connecting wires- mitted at the very high rate of severalbeing non-existent.It is this problem that"Wireless Telegraphy and Telephony." applicationThe exact measurements are immaterial, thousands per second, but this speed is not alsopreventsthesuccessful as they would probably have to be modi- possible with much increase in the length ofwirelesstransmissiontoany of the fiedwithdifferentapparatus,butthe, of the line.When a brief current of elec-systems of photo -telegraphy that have been nodiffi-; tricity is sent over a line of considerabledesigned for working over metallic con-culty should be met with in making the is Some adaptation of the alternat- lengthaportionofthiscurrent ductors. H. A. abstracted, and, by virtue of the capacitying -current method of synchronism sug-arrangement, of the line, retained as a charge upon itsgested in connection with the two recent surface.This induced charge, or "extra"systems of television just described seems current as it is termed, makes itself mani-possible,asitisa comparatively easy fest in two ways.It delays the appearancematter to arrange for the two sets of alter- A Telephone of the current at the receiving end (knownnators to run atsimilar speeds and to as retardation) and increases the perioddelivercurrentatthe same frequency. Winding "Tip" of discharge of the current after arrivalWhat is required is either some arrange- (known as prolongation).This retarda-ment whereby the two stations are set to tion and prolongation of the current has awork atthe same instant and kept in THE following tip may be of use to materialeffect upon the rateat whichsynchronism during the period of opera- amateurs who desire to re -wind their separate signals can be transmitted. tion,or some arrangement whereby thetelephones. In ordinary telegraphy a working speedpicture thrown upon the screenatthe If one has access to a gramophone the ofro,000signalsaminutehasbeenreceiver can be synchronised by the oper-matter will be found quite simple.Obtain obtained over an aerial line 590 miles inator after reception has commenced. an empty cotton reel which has a hole length, and about 6,000 signals over a line From theresultsof experiments thatthrough its centre just large enough to fit. ofr,000 miles. These figures, however,have taken place there is every reason to only represent the practical limit of work-believe that a reliable working method ing;inpractice Signals cannot succeedwill eventually be found. each other at intervals more frequent than We can say, then, that although tele- the time taken to affect the receiving in-vision working over metallic circuitsis strument.As the capacity of one mile ofalmost out of the question, wireless tele- submarine cable is equal to about twentyvision is not only possible but probable. miles of aerial line, it is evident that theWhilst the difficulties to be overcome are Winding Telephone Bobbins. effective signalling speed will be greatlyenormous and cannot be overrated they reduced on any circuit which includes anyare by no means insurmountable, andover the projecting portion of the spindle great length of submarine cable.Over theshould readily yield to organised research.of the gramophone turntable.Then take AtlanticcablesthecurrentisretardedThey are no greater in comparison thanthe bobbin which is to be wound and fix it four -tenths of a second, the working speedthedifficulties that had to be met andto the top of the reel by means of a spot beingabout1,5oosignalsperminute.overcome by the pioneer workers in otherof glue or sealing -wax.The wire can Compare thesefigures with theioo,000field of invention. M. J. M. then be attached to the bobbin and the signals per minute that are required for a turntable allowed to revolve.The speed successful television system, and itwill at whichitrevolves can, of course, be be perfectly obvious that line transmission Ask"Amateur Wireless" to send you aregulated by the controller which is fitted is totally out of the question.Wireless,list of practical books.Sent gratis and post free. to most gramophones. R. A. F. enintpitr WirelASS .i86 DECEMBER 2,1922

The Valve as Detector All About the Valve.-VII and Amplifier

WHERE one valve is utilised both asBut as the characteristic curve shows, it Therefore, although the pulses of elec- a detector and amplifier, it is gener-commences to pass a certain amount oftrons forming the grid current follow each ally in practice worked on the straight-current when the grid builds up a positiveother so rapidly during the actual per- line part of the characteristic curve oh - voltage.Accordingly as this happens, thesistence of a wave train that they have no shunt path across the grid and filamenttimetoescape completely through the no longer offers an infinite resistance tohigh -resistance path of the leak rt., yet in the signal voltage on the inductance L, butthe ensuing comparatively long period of opens up so as to by-pass through the tubequiescencebeforethenext wavetrain a part of the positive half of each high -arrives, there is ample, time for the accu- frequencyimpulseimpressed uponthemulated charge to traverse the leak and grid circuit. so re-establish the normal grid voltage, As a result, the positive pulses appliedleaving the tube readytoreceive and to the grid lose some of their effect, andrectify the next oncoming train of waves. give rise to a net increase in the plate The actual condition of the grid voltage current which is less than the theoreticalduring this sequence of events is clearly value by an amount that represents theshown in the group of curves set out in loss in grid voltage arising from the shuntFig. 14.It will be observed that the grid grid current.Meanwhile no correspond-voltage sinks in a series of small curves ing effect takes place so far as the negativeof increasing depth during the actual re- halves- of the high -frequency signal wavesception of a wave train.This is due to are concerned.These exercise their fullthe fact that during the actual period of Fig. 13.-Diagram showing Rectsfication by effect in reducing the plate current. the impact of the wave train a certain Means of Grid Leak. As the resultant increase in plate current amount of the accumulating grid 'charge under thesecircumstancesisnot sym-manages to escape through the leak re- tainedasexplainedintheprecedingmetrical with, but isless than, the re- sistance.Before all of it has succeeded article. sultant decrease throughout the durationin getting away the next pulse of electrons The usual potentiometer employed forof a wave train, the upshot is to cause thearrives and sends the voltage a stage lower. setting the grid at the "bend " points isvalue of the mean plate current to fall This alternation of the grid voltage is dispensed with, and the necessary rectifica-during that period, and this variation isimportant, as it throws light on the man- tion is secured by the use either of a simpleduly recorded by a click in the phones. ner in which one valve can function to grid condenser or more usually of a con- Meanwhile the existence of a grid cur-generatelocaloscillationsfor receiving denser shunted by a high resistance, therent also indicates that electrons have beenC.W. by the heterodyne method and at combination being known as the grid leak.carried from the filament to the grid inthe same time serve to detect the combined pulses or gushes which correspond to each"beat" effect.The sinusoidal form of the How impulses are Rectified positive half -wave of the applied high -voltage variations represents the high-fre- Such a circuit arrangement is shown infrequency signalirn Fig. 73.In order to understand clearlypulses. SIGNAL OSCILLATIONS I the manner in whiCh the signal impulses Each such pulse of are rectified by means of the grid leak itelectrons charges the VINE OF NO DISTURBANCE is necessary to refer back to the charac-grid negatively, and teristic curves shown in Fig. t s, p. 538. Asat the end of a wave cc cc previously explained,thelowersetoftrain there exists ac- GRID POTENTIAL tu¢ curves represents the relation that existscordingly a consider- 8 VARIATIONS 2cc trZERO GRID POTENTIAL between the grid voltage and thegridable accumulation of _I (Ai ILNORMAL GRID POTENTIAL current-the current which flows throughnegative electricity (2 VOLTS NEGATIVE) the grid -filament space and around the ex-upon the grid and the 2 ternal grid circuit.These grid currentsassociatedplate of are usually very small in magnitude, par-the condenserC. Un- iNORMAL PLATE CURREN) ticularly in "hard" valves, but they playless a relief path is PLATECURRENT its MILL/AMP) an extremely important part in the process VARIATIONS given to enable this rYLui'J OF ofrectification,particularlywhenthischarge toescape,it 3 ',ZERO PtagERRENT takes place, as in the present case, off the 0 will impede the main at0 "bend" points in the characteristic curve.electron flow from the TELEPHONE CURRENT to As the grid voltage swings up from zero-filament to the plate VARIATIONS ti ------4TEADI/ NORMAL CURREN/ potentialto a positive value, a currentand so clog up the THROUGH PHONES starts to flow in the grid circuit, which, innormaloperationof0 the case of the French valve, reaches athe tube. Fig. 14.-DiagramIllustrating the Mechanism of Grid -leak value of about 4o micro -amperes for a grid The high resistance Rectification. voltage of 2. R of one ortwo Now a glance at the circuit shown inmegohms is shunted across the condenserquency interaction between the plate and Fig. 13 will make it clear that the internalplates in order to supply this means ofthe grid circuits by means of which the grid -filament space of the valve is in shuntrelief.The normal interval between thelocal self -oscillation is maintained.In the to the main grid inductance L., on whichend of one series of spark wave trains andcase of a heterodyne receiver the right- the applied signal energy is building up.the beginning of the next is anything fromhand side, or "recovery" part of the curve, Normally this shunt path has an infiniteten to twenty times longer than the actualwould also be sinusoidal. D. ALCASE. resistance for zero potential on the grid.duration of any one train. (To be continued) DECEMBER 2,1922 587 etnateurWiretzs Buildyou your ownset Mullard Accessories

1 hewirelesscomponentswithaworld-wide reputation of many years standing. They will ensure your getting a set which looks well, works well and speaks well. For receiving vocal and instrumental items you must have the MULLARD "ORA" Valves to get the best results. Oscillates--Reetifies-Amplifies

Specially recommended where good amplificationis required. The "Ora " Valve requiresabout 3'8voltsonthe filament and 30 volts or over between the anode and filament for efficient results. 15/. each IMPORTANT NOTICE The great demand for Mallard "ORA" Valves and other accessories has compelled us to open much larger works.A greatly increased output is now available. The MULLARD "R" Valveisnow reduced inprice from 22/6 to 1716 tioye04. eftiN,> ct. 4 (19

re 04 Mullard Radio ValveCo.L-fd. ZS dr 0 45,Nightingale Lane, Balham, S.W.12.

111111111111111111111111111111111011,11111111111111111111111111111111111111111111i111

Confrac for s fo H.MAdmiralfy. IVerOfficeRqyalAirrorce &PosfOffice, Telephone : Codes: Telegrams : Battersea ABC (5 Ed) 'Radiovalve, Hammer' 'S? 1068 Bentley's London. .v 1e .0 cpb.c..0

AVALIATT' gluunumun RAMO MEN VALVE t) CO' Amateur Wireless 588 DECEMBER 2,1922

IMPORTANT NOTICE to all Amateurs, Experimenters, Manufacturers and Retailers We have completed the purchase of the largest stock of Ex -Govt. WIRELESS MATERIAL ever handled by an individualfirm, andit is our intention to offer the same SHARE OURfor re -sale BARGAINS at astonishingly low prices inWITH accordance with OUR our inevitable CUSTOMERS rule to We would again emphasise the fact that IT IS UNNECESSARY TO PAY FANCY PRICES FOR EX -DISPOSAL BOARD WIRELESS APPARATUS As an example of the bargains that are to follow, we are offering the following preliminary items : RECEIVERS, C.W. MARK III C.W. TRANSMITTo RS, MARK III, 30 WATT This set comprises a complete 2 -valve Receiving For two valves.Complete, with aerial, ammeter, Set, with a. wave -length range of 350-1,800 metres. platinum -pointed Morse Key, in Mahogany case. The addition of High and Low Tension Batteries, Wave -length range 300-1,800 metres. valves, and 'phones completes the entire receiving NOTE.-This set can be conveniently converted station.For the reception of Broadcast concerts thisinto a2 - valve 'Detector - Amplifying Receiver. set is ideal, the strength and clarity of the signalsPrice... £3 5 0 being absolutely wonderful. London readers shouldB MARK II RECEIVERS take the opportunity of hearing this set working at Vertical pattern. Can be easily converted to any our Showrooms. Only 200 left. Price £9 9 0 wave -length £3 15 0 Complete with 4 -volt 40 -amp. Fuller Block Accu- Above, fitted with Variable Air Condenser, .0005 mulator, 60 -volt H.T. Battery, 2 Mullard "ORA "mfds., in place of change -over switch £4 15 0 Valves, and pair of Brown "A" Type Headphones, HETERODYNE WAVEMETERS. 500-3,000METRES complete with cords £ 15 100 For Receiving, without Gal_ vanometer AMPLIFIERS, C. MARK IV ForTransmitting and Receiving,£2containing 0 0 This instrument is a complete three -valve low -fre- Weston Galvanometer ... quency amplifier, and can be used in many ways £3 0 0 without modification. AEaIAL MASTS AND EQUIPMENT The C. Mark IV. Amplifier is an improvement on 15 -feet Steel Masts in Sections, each 2 ft. 81 in., the C. Mark III. (the latter being sold by othercomplete with Halyard, Pulley, and Stays.Can be dealers at £6 Ss. Od. each without cases), inasmuch aserected by one man, and are portable.The height the C. Mark IV. contains terminals and change -overcan be increased up to 30 feet by the use of extra switch, allowing the use of the instrument for either stays. Per Set Complete ... £0 15 0 High- or Low -Frequency amplification. 30 -feet DITTO, in SECTIONS, each 4 ft.3 in. The price at which we are offering these Amplifiers (without stays).Per Set Complete £0 17 6 is less than the actual value of the transformers contained in the instrument.Puce, Complete in SULLIVAN HEADPHONES 120 ohms... . Mahogany Case... £4 50 £0 12 6 SULLIVAN HEADPHONES INSULATED AERIALS 120 ohms complete with new Telephone Transformer 40 -feet £0 1 0 60 -feet go 1 6(value 25s.) in iron case £1 10 0 Kindly note that the above prices do not include Packing and Carriage.Please add, therefore, an appropriate amount to cover this. Any surplus will be refunded. The City Accumulator Co. 179, MARK LANE, LOIN DON, E.C.3 'Phone:At,etve 1515 Wholesale and Retail Distributors for Messrs. BURNDEPT, Ltd.Same Trade Discount Allowed as by Manufacturers.

AGENTS. S.Wales: SOUTH WALES WIRELESS INSTALLATION London: H. V. ALEROW, 56, George Street, Port- CO., LTD., 18, West Bude Street, Cardiff. man Square, W.I. N. Wales, Lanes., Chas. & LO.M.: THE " ALL. Cie?..:BRISTOL WIRELESS CO.,52, Cotham Hill, BRITISH " WIRELESS MANUFACTURES CO., LTD., Bristol. 18, Vauxhall Road, Liverpool.

// \ DECEMBER 2,1922 589 mateur

Those Troublesome The Wireless Cracklings ECT I O Nand uses it he cannot qualify fo* the ex-lently for alltele- Limerick night was perimenter'sticket;but the regulationsphonic wave- Election Night and really most excit-say that he may neither make nor use it !lengths from Paris The Experimenter 2 L 0 ing. When the At any rate he must not be found withdownwardsand and firstresultcameit in his possession.How is either "A "renders coupling His Licence Sunday Morning inatabout so or "B " ever to gain the status of an ex-far more manage- o'clockthelittleperimenter?"There," in the words of aable and less sus- crowd hanging,iffamous character, "there you 'ave me."ceptibletobody one mayputitso,onthelipsofAllwireless men shouldtakethefirst capacity than the ordinary methods.At my loud -speaker thought thattherestopportunityofapproachingboththeleast I find it so. would shortly be arriving thick and fast.correspondence columns of the press, and * * the M.P.s whom their votes have just sent "Closing dowri for five minutes " said the We havenotyet hadthewireless voice.Feverishly the minutes were ticked to Westminster.Something must be done,limerick, or at any rate if any have been off ; then, with ten good seconds to go, theand that right soon. perpetrated they have not come Thermion's switches were put over."No more news; ap Let us invoke the Muse : closing down for another five minutes." * * way. A young man who lived in an attic We agreed that results couldn't after all Sunday morning.I ought really to be Had a set that was strangely erratic. be expected before half -past ten; later wegoing to church; in fact I'd practically When sparks flew from the phones made it half -past eleven, and later stillsaid I would, but we've got some people He would stifle his groans we fixed half -pasttwelve asthelikelycoming this afternoon tolistento the And put the whole thing down to static. zero hour for the great rush.It neverDutch Concert and one wants to get the Sorry to use an Americanism ("static" came.Results, quite a number of them,thing all right.Yes, I know I did say ismerely our oldfriend-or enemy- trickled in, but the man with the pencilpractically;butpractically'snotabso- atmospherics), but there did not seem to was never really overworked.However,lutely definitely, and-hand me the smallbe anything to rhyme with atmospherics. we heard a great many long before lesserscrewdriver,there'sadear,and-con-Still, on second thoughts, how's this? men relying on the "land line " couldfound this infernal nut, rolled under the A wild man who lived close to Berwick's possiblydoso, andthehalf-hourlytable, dear.. . Thanks.Haven't seen Fine town was renowned for homerics; resumes of the state of the parties providedmy soldering -iron lately,I -suppose?Is When he wirelessed his speeches both the optimist and the pessimist present His screams and his screeches that the last bell ?Well, that settles it; Were mistaken for strong atmospherics. with all the material that they needed toIcan'tpossiblygo now. I'vegota prove that their fondest hopes or worstmouthful of nuts.Not that I don't want * fears were in process of realisation,Whatto go;Ido, but with allthese people Are you troubled at times with crack- anevening outitmust have beenforcomingthisafternoonIfeelIought lings in your receivers which cannot be 2L O's announcer. News at six, more news-to--They're - not coming ?Well, now duetothebalefulinfluenceofatmo- at nine, and election results from then tillI've wasted the whole morning, missedspherics?Most of us are.As a rule the oneinthe morning.His microphonechurch and everything.Of course, you H.T.batteryistheculprit,especially did not seem to be quite so good as usual,go, dear.It wouldn't do for both of uswhen itis no longer initsfirst youth. forit was inclined to blur s's and f's.to stay at home. . . Good-bye ! The remedy istouse a farlarger by- Possiblyit,too,felt the strain alittle. Now. Round abouti,000metres,I pass condenser across its terminals than The new chimes which strike the fourthshould think. Hallo, who's this? "Abide isusually recommended.Most writers quarter and then the hour are quite awith me." Yes,I ought to have gone tolay down that from .o3 to .3 mfd. is the feature.Phones and loud -speakers repro-church. Who's 2N P, or is it M P ?Rag- most suitable capacity.As a matter of duce them with amazing clearness. time now.Riddles, rather an amusingfactInever use less than s mfd.;,- and * * * * cove, this.I'll just push the condenserfrequently double this capacity when the Curious thatthe non -technical papersback a bit.Le Bourget talkingtoSt. battery is growing old.You will find, too, have been almost as .silent as the graveInglevert. " The :'resident of thethatifyou employ low -resistancetele- over the broadcast licence question.Is Republic wants to talk to St. Inglevert."phones it pays to shunt across them some- it that they do not realise what has beenPresident's a bit- sticky at the microphone.thing much bigger than the .0005 or .001 done ?The position is utterly ridiculousCroydon as loud as ever and Pulham ex-condenser of convention.If the phones when you come to think of it."A," whocellent.I'll keep the same coils on andare of the high -resistance type the larger is keenly interestedinwireless,wishes switchthe condenserinseries. Here'scondenser does no good at all, but with to make some experiments which may leadsomebody on about 400.I can hear whatlow -resistance gear capacities up to .025 toa useful discovery.He istoldthathe says but Ican't catch his call sign.mfd. may be used with advantage.Tests as he cannot show a satisfactory recordWonderful difference a condenser acrosswith various condensers will soon show of previous experience he must contentthereactancesnakesonshortwaves. which capacity is best suited to the phones. hissoul witha- broadcastlicence. He 2L O was good last night, by the way, .54 obtains a "hall -marked "set,butfinds though theitemswererather on the * that if he tinkers about with its circuits gloomy side.I think I've found the ideal Answer to Correspondent :No, Harold, he is guilty of an illegal act. Exasperated,combination now, and that is basket coilswe can see no use in the wireless set for the he applies again to be ranked as an ex-for the A.T.I. and one of Tingey's A*valve which your dear little boy connected perimenter, only to learn that thefactcoils in the reactance with a large capacitytothe high-tension battery " to. see the that he possesses and Works a broadcast variable condenser acrossit. Thisre- pretty fireworks."However, the missis setisnot regardedasgiving him theactance coil, if adequate use is made ofwill find it most useful to push inside socks necessary qualifications."B," again, has the,threetappingstudsandofthe when she is darning them. designed an briginal set.Unless he makesvariable condenser -across - it,does excel - THERMION. Virekss 590 DECEMBER 2,1922 A Novel Utility Aerial

UTIL such time as aerials as we knowin mind, Chambers and Ellis, of Cravenand another adjustable insulator is pro- them to -day are no longer necessary,House, Kingsway, London, W.C.2, havevided by means of which the necessary even with comparatively simple sets, theput on the market what they term thelength of span easily can be secured. The "Esi-Fix " aerial. The claims made fortheaerial, and thereis no reason that they should not -besubstantiatedinactualpractice,. are that it can be simply throWn up anyhow and anywhere, over a roof, for instance, or over a tree, without any precaution being necessary with regard to insulation. Also,thereisnonecessitytocutthe aerial to an exact length asitis made adjustable. The lead-incanbe made through any open window, and itis im- material whether the wire touches external objects such as window frames, masonry, etc:No insulators or supporting wires are required. This all seems very wonderful, not to mention the convenience, hut the resultis obtained in a very simple way though the invention is none the less of value because ofthis.The aerialis composed of 40 strandsofNo.30 -gauge wire with an outer covering of a patented tough rubber Photograph of Aerial on Chimney. compound whichisimpervioustowet Photograph showing Down Lead and and will not rot or corrode.It will be Adjusting Device. task of fixing those of the orthodox typeapparent that the combined construction will always be a troublesome matter inprovides at one and the same time anaerial is made in lengths of too ft., 75 ft. the case of seventy-five per cent. of would-aerial and the necessary insulation.One and so ft.; additional cable can be had bewirelessenthusiasts,and,therefore,end of the wire is fitted with a porcelainif required. any idea that tends to reduce the troubleinsulatorto provide a means of attach- The two photographs show the aerial in will always be welcome.With this ideament rather than to act as an insulator,use under different conditions.

An Interference -prevention Circuit 11

EPERINIENTERS - who are troubledductancevariablycoupledtothetwothesecondarycircuitshouldbe tuned with interference should try the cir-primaries. until the desired signals arc heard at their cuit shown below (Fig. 1), as it has proved Coils of the honeycomb and basket typesstrongest. Then thecondenser ofthe very selective in use.As will be seen theare particularly sui,tible for this circuit onothercircuitisvaried untilinterfering signals are cut out. It Nvill probably be found that the coupling between the three coils has 'to be carefully set completely to cut out the interference. For receiving C.W. signals by the re- action method itis advisable to split the C: secondary inductance, using one half in the interference -prevention circuit and the other half coupled to a reaction coil in the plate circuit (Fig. 2).In this case the re- action -coupling coils should be far enough away from the primary circuits to prevent energy being returned to the aerial. Fig. 1.-Interference-prevention Circuit. Fig. 2.-Modified Interference -prevention Circuit. L. A. W. primary circuit is divided, and each halfaccountoftheircompactness.There- The WesternTelegraphCo. have contains an inductance and a condenser.quisite sizes will, of course, depend uponlodged a claim with the Irish Provisional Theinductancesshouldhavesimilarthe wave -length to be received., Government forthedestructionof the values.The secondary circuit has an in- In operation the primarycircuit andValentia Cable station. , DECEMBER 2,1922 591 emateur Wireless Transatlantic Tests. -TheLondon ElectricSupply Company have kindly allowed the use of their premises for one ofthetransmittingstations. A zoo -ft. The Experimenter's Licence for chimney isavailable for running up an aerial.Operators willing toassist and the Home-made Set who do not mind sitting up between 12 I midnight and 6 a.m. should write to the hon. secretary. WE print belowa copy of a letter receivingapparatusforexperimental Prizes for Armstrong Regenerative Cir- that has been received by an ama- purposes; and such licencesare nowcuitSefs.-A first prize of Lis and the teur from the Secretary of the General Post only issued to persons who make theirsecond prize of Lio is being presented by Office in response to an application for a own sets,or to persons who producetwo members of The Wireless Society of receiving licence.The letter is self -ex- evidence that they have in view someLondon (who desiretoremain anony- planatory and needs no comment, beyond Abjectofscientificvalueorpublic mous) for the best instrument employing pointing out that it endorses the advice utility, and that they are qualified tothe principlesofthe Armstrong super - that we have consistently given to those make proper use of the facilities theyregenerative circuit.The conditions are : who have made their own sets to apply desire.If you wish for a licence of this (i) The ruling of aspecial sub -com- for an experimenter's-and not a broad- description, it will be necessary to askmittee of the Wireless Society of London cast receiving-licence. you to produce such evidence. will be final. " Withreferencetothebroadcast P.O. Ref. No. 147990/22. (2) No more than three valves shall be licence above referred to, I am able toused, and the set must work on a loop GENERAL POST OFFICE, explain thatthe British Broadcastingaerial which must accompany the instru- LONDON, E. C. 1. Company is an association of manufac-ment when itis sent in for judging, to- 16th November, 1922. turers who havecombinedtoerectgether with a diagram and what is claimed "With reference to your application stations for broadcast transmission, andfor the instrument as to performance. of the 6th November, I am directed by to arrange for the broadcasting by means (3) Those desiringtoenterthe com- thePostmaster -Generalto saythat of those stations of regular and suitablepetition must he members orassociate licences for wireless apparatus for the programmes of music and other matter. membersoftheWirelessSocietyof reception of broadcast matter are con- The cqmpany is open for fair and easyLondon,ormembersofanaffiliated finedto apparatus which is manufac- terms to every bona -fide British manu-society. The competition will close Decem- tured by, members- of the British Broad- facturer of wireless apparatus, and everyber loth.All apparatus must be sent in casting Company, and which bears the set bearing their trade -mark contributesto the hon. secretary before that date. registered trade -mark of that company, by a suitable percentageof the sale - (4) Each competitor will be allowed to indicating that the apparatus is of a type price to the heavy expenditure of thedemonstratehis own instrumentifhe approvedbythePostmaster -General. company in the erection of suitable sta-desires, or he may depute someone to do The range of reception in the case of tions or programmes.I am to add thatthis,failingwhich thecommittee will such apparatus will not be limited to the approval given by the Postmaster -make their own tests according to written a particular band of wave -lengths, and General to setsmanufactured by mem-instructions. Some constantsourceof in view of this fact it is thought that a bers of the company indicates only thattransmission will be arranged for all of the licence of this kind will probably meet such sets comply with his technical re-tests. Inallprobabilityitwillbe your requirements.If not, the alterna- quirements, andisno guarantee ofarranged that the prize winners will ex- tive would be a licence for the use of efficiency or. workmanship.- hibit their sets at a meeting of the Wire- less Society of London if, they agree to do SO. The following points will be taken into consideration in judging : WirelessSocietyof London (a) General design. (b) Adjustmentinminimum timeto (The Radio Society of Great Britain) maximum efficiency. (c) Resultant signal strength. Note:External finish will not be taken Change of Name gramophone or otherwise), not exceedinginto consideration. AT thespecialgeneralmeeting heldfive minutes in duration, to be permitted OWN.,.W..."..."../C) on November 22nd, the name of thefor testing purposes, and a total trans- society was officially --altered and hence-mission at one time of not more than to A Hlstorlc Event forth will be called "The Radio Societyminutes, with a total transmission of fourWE have received from Marconi's Wire- of Great Britain." such periods (40 minutes) in all, duringless Telegraph Co. a copy of the souvenir any one evening from 6 to x x p.m. ; otherthat has been prepared and sent, to persons Amateur Transmissions.-The commit-hours of the day being free except that thewhoreportedonthetransmission, of tee which was appointed at the meeting offive' minutes' limit of music transmissionH.R.H. the Prince of Wales's ,speech to those holding transmitting licences in theshall apply. the Boy Scouts on October7th. This London disrict have unanimously arrived (2) These arrangements only to applysouvenir, which is very attractively got atthe following suggestions and theseto working in the 440 -metre wave -length. up, gives H.R.H.'s speech in full, and a will be submitted to the next meeting. (3) Holders of transmitting licences arelist of the persons who heardit.2L 0 (I) It isagreedthata voluntaryreminded of the terms of theirlicenceemployed onthisoccasion a twin -wire arrangement be made tostop broadcastwhereby they must use their call sign be-aerial, the wave -length being 36o metres. music transmissions except where specialfore and after each transmission. The power used was 1% kw., and the permission has been obtained from the (4) .The use of spark transmissions bytransmission was heard on a crystal set G.P.O.,inwhich casethis should beamateurs on all wave -lengths and tonicatCambridge,somiles from Marconi stated before, during and after the trans-train on 440 -metre wave -length should beHouse, and on a 4 -valve setat New - missions. Musictransmissions(eitherabolished. quay, 240 miles away. eintatut-'Wirelkss 593 mateur Wireless AMATEUR WIRELESS" IDEAL UNIT RECEIVING SET This is the second article of the series that Mr. R. W. Hallows Rectifying Panels in placecertainleads can be attached is writing by special request. The instalment given in thisissue fastened to No. 2 of the terminal panel, The way in which the rheostats are fitted WHETHER itisintended thatthe permanently to it,so that the connection the detector unit can be connected toit to the panel depends entirely upon their first unit of the apparatus shall be and disconnect,ion of wires are reduced to deals with rectifying panels, by means of two notched Mass strips.The design.It is necessary, as a rule, to let a crystal detector or a valve rectifier, the a minimitm. telephonesandvariablecondenserare them into the wood for3(in.or so in readerisstronglyadvisedto begin by wired up as shown, and as soon as we have order to allow plenty of clearance below making the terminal panel, which is the r the end of the spindle, but this is a matter Terminal Panel drilledin batchesof three or four at a as we shallseelater how to convertit made some kind of inductance coil tofit foundation of the whole set.Once itis The photograph (Fig. i) shows the panel thevalve -socketstheunitiscomplete. that presents little difficulty if a chisel or time. into a combined high -frequency valve and with four terminals, and the sable number The block for the terminal panel should detector panel,itis just as well to pro- You cannot do better than use a set of appears on all the other units.Since the be of hard wood of exactly the same height vide it with them when'it is first made up. basket coils, seven of which, tuning from photographs were taken an additional one and length as the unit panels.Clamp the Prepare two strips as before, but bore 25oto4,000metres witha.00imfd. has been added throughout the set, which strip on toitand make a prick in the the in.holesbeneaththemright variablecondenser,can be boughtfor is found to serve a variety of useful pur- wood exactly inthe. centre of each ter-. through the wood of the panel.Now take about 6s.Make sure that your coils are VALVE SOCKErs posesIt isalways handy .to have an heavily shellacked and not merely dipped DOREWED IO minal.Next remove_ a_ strip and bore r" a piece of ebonite measuring 2 in. by in. NI TS extra terminal, particularly when experi- in paraffin wax, otherwise they will not last - %-in.holeabout in.deepateach - and mount on it a pair of valve -sockets mentingwithnewcircuits. Forthis mark.Fit the terminals to the strip. and i in.apart from centre to centre.-Bore long.Mount each on an ebonite block as reason the reader will do well to adopt put.itinplace,seeingthatthenuts in.holes through ,the wood totake shown in Fig. 6, provided -with a pair of five -terminal units rather than those with or" bolt -heads on the under side are quite their lower ends, and fix the block quite valve prongs spacedtofitthesockets. four only.One set of terminals will nor- clear of the wood.If there is any contact close to the top edge of the panel (Fig. 4). This is done most easily by sandwiching mally not he in action, but we shall see theoffendingholeorholesmustbe Another strip to take- the detector is fitted the coil between the ebonite block and a later how they may be used to advantage slightly enlarged.Cut a small notch in as shown in the drawing.Place it quite strip or disc of the same material held in when we come to discuss possible refine- the wood leading to 'each hole, as shown If.nearthepiececontainingthevalve - place by a screw. Fig. 1.-Photograph of Terminal Panel. ments of the circuits shown. inFig.3. These should be justlarge sockets,so that plenty of room may be For the terminal panel we require a enough to take comfortably the insulated left on the panel for the valve -holder and The V alve.rectifying Panel strip of ebonite measuring S in. by in. wire that you.propose to use for your bat- The valve -rectifying panel is not at all EBONITE Ton VALVE SOCKETS rheostat which will be added later when / by in. or in. thick.This should be tery and otherleads. Ifitisintended we come to make the conversion.MOUnt difficult to make.Figs. 7 and S show its Fig. 10.-Photograph of Accumulator bored as shown in Fig.2. All the holes toproceedstraight away with the con- the detector on thisstrip, boring in. appearance when seen from above and 00 with Valve Sockets Fitted to Terminals. are Lain.The two nearest the ends are structionofthevalve rectifying panel, holes as before below the crystal cup and from below.To fix the valve -holder in 0 0 for the screws which fix the strip, and the these leads may now be attached to the the pillar. place bore a hole y4. in.in diameter in wood block upon whichitrests,to the lower ends of their respective terminals, The wiring may now -be carried out as the panel, which will give the legs plenty 0 0 0 table. The remainingfiveareforthe (0 and the strip and its block can be fixed to shown in Fig.;. Use fairly- stout wire, of clearance, and then fasten with screws. EliOnirfFOR OEI EC TOR VE,77E PRONG SOLDERED 3 B.A. terminals, whose heads should be the table.If, however, the crystal detec- about No. 24 s.w.c., and pass each piece The rheostat should have a maximum 0 0 ro LEADrsom TEArvelAL as large as possible, with good flat contact PANEL tor is to be the next step, no wires need throughalengthofinsulatingtubing. resistance of about S ohms.Several excel- surfaces.As allthe ebonite strips used be attached before the panelisscrewed Each erid of all wires should be soldered lent types are on sale now very cheaply. 0 EBONITEFOR 0 VALVE SOCA E are identical, except that for those fitted down. to a 3 B.A. washer, as described in the Threeofthoseused intheset which TERMINALS SCREWED IN --N. to the unit panels the screw holes should lastarticle ;these can- then he clamped appearsinthephotographscostonly 0 0 be onlyligin.in diameter,itis a good The Crystal Unit Panel tightly by the lower nuts of the terminals. 2s. 6d. each, and nothing could he more plan to make a number at once.They The crystal unit does not actually re- If now the aerial lead-in is taken to ter- satisfactory, for their action issilent and L____. canconvenientlybetrimmedupand quire thefull number of terminals, but minal AcCunK,L.A,0* and the lead from the earth is perfectly smooth. TENA,NA4. Fig. 4.-Diagram showing Positions of Ebonite Strips.

Fig. 11.-Detail of Accumulator TerminalwithValve -socket 7iNENNAL PANEL Connector. , A - d'tn. BRASS 50AIA5 LI0

*4/ 0 dit'IT.SE:17Dj EBOAIrr

I 1 SECONDARY

.0003-L-12 0005-7:: 0005 VE PRONGS IZ-_ _ _ . Lta u I Fie. 6.-Detail of Coil Holder I _77'PRIHARY

I I .`;00,07';',000? RFEEk' .ERE with Coil. COIE 1,,,E '1"1.50,? - 0

Fig. 7.-Photograph of Valve Rectifying Panel. 9. O e" L _ _ _J =r-- Norc, 0 0 O ; Lill A_ .01./05 7 CON L r A fig. a Fig. 3 REACTION 6v. 60 v. Fig. 5.-Wiring Diagram of Crystal Unit Panel. Figs. 2 and 3.-Details of Ebonite Strips and Wood Bloek. Fig. 9.-Wiring Diagram of Valve Rectifying Panel. Fig. S.-Under-side View of Valve Rectifying Par el. eintatut-'Wirelkss 593 mateur Wireless AMATEUR WIRELESS" IDEAL UNIT RECEIVING SET This is the second article of the series that Mr. R. W. Hallows Rectifying Panels in placecertainleads can be attached is writing by special request. The instalment given in thisissue fastened to No. 2 of the terminal panel, The way in which the rheostats are fitted WHETHER itisintended thatthe permanently to it,so that the connection the detector unit can be connected toit to the panel depends entirely upon their first unit of the apparatus shall be and disconnect,ion of wires are reduced to deals with rectifying panels, by means of two notched Mass strips.The design.It is necessary, as a rule, to let a crystal detector or a valve rectifier, the a minimitm. telephonesandvariablecondenserare them into the wood for3(in.or so in readerisstronglyadvisedto begin by wired up as shown, and as soon as we have order to allow plenty of clearance below making the terminal panel, which is the r the end of the spindle, but this is a matter Terminal Panel drilledin batchesof three or four at a as we shallseelater how to convertit made some kind of inductance coil tofit foundation of the whole set.Once itis The photograph (Fig. i) shows the panel thevalve -socketstheunitiscomplete. that presents little difficulty if a chisel or time. into a combined high -frequency valve and with four terminals, and the sable number The block for the terminal panel should detector panel,itis just as well to pro- You cannot do better than use a set of appears on all the other units.Since the be of hard wood of exactly the same height vide it with them when'it is first made up. basket coils, seven of which, tuning from photographs were taken an additional one and length as the unit panels.Clamp the Prepare two strips as before, but bore 25oto4,000metres witha.00imfd. has been added throughout the set, which strip on toitand make a prick in the the in.holesbeneaththemright variablecondenser,can be boughtfor is found to serve a variety of useful pur- wood exactly inthe. centre of each ter-. through the wood of the panel.Now take about 6s.Make sure that your coils are VALVE SOCKErs posesIt isalways handy .to have an heavily shellacked and not merely dipped DOREWED IO minal.Next remove_ a_ strip and bore r" a piece of ebonite measuring 2 in. by in. NI TS extra terminal, particularly when experi- in paraffin wax, otherwise they will not last - %-in.holeabout in.deepateach - and mount on it a pair of valve -sockets mentingwithnewcircuits. Forthis mark.Fit the terminals to the strip. and i in.apart from centre to centre.-Bore long.Mount each on an ebonite block as reason the reader will do well to adopt put.itinplace,seeingthatthenuts in.holes through ,the wood totake shown in Fig. 6, provided -with a pair of five -terminal units rather than those with or" bolt -heads on the under side are quite their lower ends, and fix the block quite valve prongs spacedtofitthesockets. four only.One set of terminals will nor- clear of the wood.If there is any contact close to the top edge of the panel (Fig. 4). This is done most easily by sandwiching mally not he in action, but we shall see theoffendingholeorholesmustbe Another strip to take- the detector is fitted the coil between the ebonite block and a later how they may be used to advantage slightly enlarged.Cut a small notch in as shown in the drawing.Place it quite strip or disc of the same material held in when we come to discuss possible refine- the wood leading to 'each hole, as shown If.nearthepiececontainingthevalve - place by a screw. Fig. 1.-Photograph of Terminal Panel. ments of the circuits shown. inFig.3. These should be justlarge sockets,so that plenty of room may be For the terminal panel we require a enough to take comfortably the insulated left on the panel for the valve -holder and The V alve.rectifying Panel strip of ebonite measuring S in. by in. wire that you.propose to use for your bat- The valve -rectifying panel is not at all EBONITE Ton VALVE SOCKETS rheostat which will be added later when / by in. or in. thick.This should be tery and otherleads. Ifitisintended we come to make the conversion.MOUnt difficult to make.Figs. 7 and S show its Fig. 10.-Photograph of Accumulator bored as shown in Fig.2. All the holes toproceedstraight away with the con- the detector on thisstrip, boring in. appearance when seen from above and 00 with Valve Sockets Fitted to Terminals. are Lain.The two nearest the ends are structionofthevalve rectifying panel, holes as before below the crystal cup and from below.To fix the valve -holder in 0 0 for the screws which fix the strip, and the these leads may now be attached to the the pillar. place bore a hole y4. in.in diameter in wood block upon whichitrests,to the lower ends of their respective terminals, The wiring may now -be carried out as the panel, which will give the legs plenty 0 0 0 table. The remainingfiveareforthe (0 and the strip and its block can be fixed to shown in Fig.;. Use fairly- stout wire, of clearance, and then fasten with screws. EliOnirfFOR OEI EC TOR VE,77E PRONG SOLDERED 3 B.A. terminals, whose heads should be the table.If, however, the crystal detec- about No. 24 s.w.c., and pass each piece The rheostat should have a maximum 0 0 ro LEADrsom TEArvelAL as large as possible, with good flat contact PANEL tor is to be the next step, no wires need throughalengthofinsulatingtubing. resistance of about S ohms.Several excel- surfaces.As allthe ebonite strips used be attached before the panelisscrewed Each erid of all wires should be soldered lent types are on sale now very cheaply. 0 EBONITEFOR 0 VALVE SOCA E are identical, except that for those fitted down. to a 3 B.A. washer, as described in the Threeofthoseused intheset which TERMINALS SCREWED IN --N. to the unit panels the screw holes should lastarticle ;these can- then he clamped appearsinthephotographscostonly 0 0 be onlyligin.in diameter,itis a good The Crystal Unit Panel tightly by the lower nuts of the terminals. 2s. 6d. each, and nothing could he more plan to make a number at once.They The crystal unit does not actually re- If now the aerial lead-in is taken to ter- satisfactory, for their action issilent and L____. canconvenientlybetrimmedupand quire thefull number of terminals, but minal AcCunK,L.A,0* and the lead from the earth is perfectly smooth. TENA,NA4. Fig. 4.-Diagram showing Positions of Ebonite Strips.

Fig. 11.-Detail of Accumulator TerminalwithValve -socket 7iNENNAL PANEL Connector. , A - d'tn. BRASS 50AIA5 LI0

*4/ 0 dit'IT.SE:17Dj EBOAIrr

I 1 SECONDARY

.0003-L-12 0005-7:: 0005 VE PRONGS IZ-_ _ _ . Lta u I Fie. 6.-Detail of Coil Holder I _77'PRIHARY

I I .`;00,07';',000? RFEEk' .ERE with Coil. COIE 1,,,E '1"1.50,? - 0

Fig. 7.-Photograph of Valve Rectifying Panel. 9. O e" L _ _ _J =r-- Norc, 0 0 O ; Lill A_ .01./05 7 CON L r A fig. a Fig. 3 REACTION 6v. 60 v. Fig. 5.-Wiring Diagram of Crystal Unit Panel. Figs. 2 and 3.-Details of Ebonite Strips and Wood Bloek. Fig. 9.-Wiring Diagram of Valve Rectifying Panel. Fig. S.-Under-side View of Valve Rectifying Par el. lettuxtegr 594 DECEMBER 2.1922 gouge is available.If the spindle passesowing to their low self -capacity. 'It is not3.30 p.m. are discontinued, and the trans- through a brass bush, itis best to makedifficult to make an adapter which willmission that was given at 5.10 p.m. is now in the wood a hole big enough to clearallow them to be used on holders designedsent out at 6.20 p.m. itentirely. The bushisthenpassedto take honeycomb or lattice -wound coils. through a thin piece of ebonite, which isA very cheap set, of coils can be made by screwed down to the top of the panel. mounting a set of seven baskets and the A numberofGlasgowanddistrict five largest of a set of eight slabs in theamateurs report that when receiving they Don't Economise on the Grid Condenserway mentioned.The baskets will attuneare greatly troubled by the phenomena There is one direction in which itis to 4,000 metres, beyond which wave -lengthknow as "fading." One amateur puts it folly to economise when building a valvethe slabs can be used for receiving anydown to the erratic running of the genera- set. A cheap, badly -designed grid con-existing stations.Even Bordeaux's 23,45otor at the transmitting station, while an- denser and leak will often be responsiblemetres are not too much for the largest ofotherthinksthatisitwholly due to for poor and irregular results.The con-the coils.Slabs are not so efficient asatmospherics.In next week's issue we denser is about the only one in the wholebaskets, but they will be found quite goodhope to have an article on the subject. set whose value is critical, and it must befor the longer waves, on which, after all, well made.Cheap grid -leak; are some-one rarely listens in.Such a set of coils, timesmadeof hygroscopicmaterial,complete with their mountings, will not which causes the resistance to drop enor- A wireless telegraph stationisto be cost,,much more than a sovereign all told, erected at Gremeton, near Varbeg, mously in damp weather, often tothe and with them one covers the whole rangeSweden, for communication with America. entire mystification of the user, who can-from 200 to 30,000 metres. not understand the poor performance of R. W. HALLOWS. - his set. Good reception of Marconi Houseis Place the condenser on the upper side reportedinthe Glasgow districtusing of the panel just in front of the valve. only asingle valve, the distance being The leak can then be changed without any nearly 400 miles.At Bridge of Allan, trouble if its valve does not suit the valve stillfarther away from the transmitting in use. Radiograms station,loudspeechisreceivedon a In the photograph the leads for the re- small two -valve "Marconiphone,." which action coil are shown as running to a pair has a guaranteed range of only so miles, of sockets at the lower end of the panel. AT the annual dinner of the Society ofwhile similar experiences are obtained in This isa convenient arrangement, for it Authors, Playwrights and Composers,Glasgow, using two valves of an "Etho- enables the coil and the condenser to beheld on November list, Major Ian Hayphone III," guaranteed range 8o miles, plugged in in a moment, whilst if reactionBeith, who presided, mentioned the factand with pairs of phones fitted. is not in use the sockets are short-circuitedthat any question of licensing an agency I by means of a pair of plugs mounted on awhich was going to broadcast music with- brass strip.Possibly, however, it wouldout payment to those immediately con- Inalettertothe"Aftenposten," a be even better to take these leads to ter-cerned, should be leftto the society toNorwegian paper,datedAugust,1922, minals standing on thesurfaceofthedecide upon. Captain Amundsen says :"The wireless functions brilliantly.We hear Stavanger panel, shorting being done when necessary by means of a swinging hook, made of Radio clearly and distinctly every day sheet brass:attached permanently to one Itis stated that the callletters 5H Xat the appointed hour." of the pair., have been allocatedto an experimenter The valve used for the rectifying panelfor the purpose of carrying out experi- The United States Army Air Service should be prdferably ofthe rathersoft mental transmissions from racing cars on Brooklands motor track. isexperimentingwithakiteballoon type.It is possible to use the same valves which.carriesacameracontrolledby for both amplifying and rectifying,but wireless.By this means, during war, it better results will be obtained if the recti- The TerritorialSignalling Sectioninwillbepossibletophotographlarge fier is provided with a valve with not aGlasgow isgiving wireless amateurs intracts of land without any of the usual very high degree of vacuum, hard valvesthe district excellent Morse practice everydangerassociatedwithaerialphoto- being used on the remaining panels. night.Morse is transmitted by the terri-graphy.

Fig. 9 shows the wiring of the panel,torials between 7 p.m. and 8p.m.. on which should not present any great diffi-1,900 metres.Three nights a week itis culty.See that all wires on the undersent at speeds between ten and fourteen A noveltywasintroducedintothe side of the panel are a little slack. words a minute, and on the remainingDevonshire House election -night ball by nights the signals are at a faster rate. the transmission of music from a cellar Accumulator Connections to a lacquered box situated in the ball- A usefultipfor making accumulator room where the guests were dancing. The connections is 'shown in Figs.o and The United Fruit Co. is providing freebox, which was a cleverly concealed re- A valve -leg is screwed into the top of eachmedical service by radio from its hospitalsceiver, took the place of the orchestra. in its terminal, a ,prong being soldered to each Central America, and from pas- or lead running from the low-tension batterysenger shipsatseato other ships not having a doctor on board. In Scotland tenement dwellings are very to the terminal panel.This saves all the numerous, and many difficulties have been bother of unscrewing and screwing down le experienced in the erection of aerials by terminals when the accumulator is being The President of Brazil has sanctionedresidents therein. A novel suggestion has connected up,butthepresence ofthe theinstallationof high power wirelessbeen made that a stout cable should be valve -legs in no way interferes with thestations, and the establishment of a wire-stretched parallelto a tenement and at free movement of the milled -headed nuts,less telephone service on Brazilian terri-some distance fromit,the ends being which can be used in the ordinary waytory by the Agencia Americana. attached to the chimney stacks of adjacent when the battery is sent to be re -charged. tenements running at right angles to the Any type of, three -coil inductance will one which isto be served."This cable work well with thisset.For short-wave The following /alterationshave beencould be used to support any number of reception basket coils mounted as alreadymade inthe broadcasting timesof theaerials running fromittothevarious describedareparticularly recommended EiffelTower :Theconcertsgivenathouses in the tenement. DECEMBER 2,1922 595 =lair Wtretess OUR INFORMATION BUREAU Expert Replies to Readers' Questions.Hundreds of Replies are sent by Post. TO ENSURE A PROMPT REPLY PLEASE OBSERVE THE FOLLOWING RULES Write distinctly, give all necessary details and keep to the point.Ask one Question at a time-never more than two.Send a Stamped and Addressed Envelope. Send the Coupon cut from page 598.

Flickering Valve. correspondence column, and think the re- Q.-Can you explain the reason why my sultsI have obtained would be of some valve occasionally flickers and the light ceasesinterest to other amateurs.I am using- a momentarily and then lights up again for no high, an in- CLUB DOINGS I apparent reason ?-P. G. K. (Bristol)(4312). 6o -ft.twin -wire aerial 34 ft. A.-Provided you are positive that yourductively -coupled tuner with condensers, connections are quite in order and that yourand a " Hertzite " crystal with fine copper variable arm fits tightly on your rheostat, we wirecontact. Ship andcoast -stations Lambeth Field Club and Morley can only suggest that possibly one set of the come in very strongly, and clear signals College Scientific Society accumulator plates is broken internally from Hon. Sec.-MR. W. RIVERS, Morley College, one of the accumulator terminal.It may beare received from Harwich, Niton, NorthWaterloo Bridge Road, making contact ordinarily, but any slight jarForeland, Sheerness and the ContinentalTHE Hon. Sec. invites application for mentLer- or vibration will cause the broken connectionstations at Boulogne, Dunkirk, Le Havre,ship of the above society. to jump apart and thus cause your valve to go:Ostend and Scheveningen.The commer- out.Any loose matter between the plates Sale, Altrincham and District Radio would also cause the trouble.-L. C. cial stations, Paris and Nauen, are always Society loudly received, and Ihave also heardHon. Sec.-MR. H. FowTER, Alston, Oldhall Karlsborg, Madrid, Moscow and Petro-Road, Sale. BROADCAST TELEPHONY grad.Telephony between Croydon, whichA SOCIETY has now been formed calledthe Some o/ these transmissions are commercial is17 miles away, and aeroplanes on theSale, Altrincham and District Radio Society, or official.Wave -lengths and times are liable London -Continental route is always verywith headquarters at the Reform Club, Sale. It is proposed to form a ladies' section and to alteration without notice. loud. Speech from Marconi House five - London B.B.C. Station (21. 0), 365 metres. also a junior section.Full particulars can he miles away, can be heard 2ft. from the obtained fromthe hon. secretary. ' Daily, usually 6 p.m. to TO p.m. 'phones and can still be loudly received ManchesterB.B.C.'Station(2Z Y), 385 Plymouth Wireless and Scientific metres.Daily, usually 6 p.m. to 9 p.m. when a frame aerial is substituted for the Society BirminghamB.B.C.Station(2W P),425 ord4nary one.The concerts from Writtle, metres.Daily, usually 6 p.m. to 9 p.m. 35 miles away, are very good, every wordHon. Sec.-MR. G. H. Loos, 9, Ryder Road, Croydon (G E D), goo metres.Daily, Stoke, Devonport. Writtle (2M T), 400. metres.Tuesdays, 8 p.m. being clearly heard.On one occasion ION Oct. 31st a meeting of the Society was held; EiffelTower (F L),2,600metres. Daily, was surprised to hear faint telephony fromat which a lecture was given- by Mr. G. H. 6.20 p.m. to 7 p.m. the Eiffel Tower station.With regard to Lockon" WirelessReception."Dealing The Hague (P C G G),1,o85 metres. Sun- the transmission of telephony by amateurs,with the subject historically to begin with, the days, 3 p.m. to 5 p.m. lecturer referred to the pioneer work of Hertz, Rome (I C D), 3,20o metres.Daily. I have received speech and music from theBranley and others, carrying the audience up Konigswusterhausen(L P), 2,800 metres. following :2B Z, 2L U; 2L V, 2L W, aM I,to the point where Marconi came upon the Daily, 4 p.m. to 5.3o p.m. 20 M, 20 N, 2Q Q, 2S I,2S W, 2U V, scene.The principles of tuning were then Amsterdam (P C A),1,800metres. Daily, 2W P, 2X X, 5C P.I 'should be pleased toexplained, and then magnetic and crystal 1.10 p.m. detectors dealt with.The Edison effect, the Haren (0 P V H), goo metres.Daily, every hear if any other reader has had resultsFleming two-electtode valve and ultimately hour f1-011111.20 a.m. to 4.20 p.m. equal to mine in the reception of low -the three -electrode valve followed.A typical power amateur telephony.-W. E. N. W. characteristic curve was shown, and the recti- (Harlesden, N.W.to). fying and amplifying points explained. Mag- netic reaction and the reception of continuous CORRESPONDENCE Experimenting with a Crystal waves completed the lecture.A demonstra- n.nrs.n.nnnws".".".".".nwraewv~".) Sir,-With regardto your correspon-tion followed, during which, by means of a letterremyarticle-publishedseven -valve set, the lecturer was able to show Berkhamsted Wireless Society and dent's practically the principles of beat reception. the Broadcast Licence November 4th, I agree- with him: that the SIR,-I should esteemita favourif current passed by a crystal is not directly Coventry and District Wireless you would draw the attention of wirelessproportional to the applied voltage, but Association societies to the following, resolution passedthere are ways (as no doubt your corre-Hon. Sec.----J.E. Bor.us, " Iona," 14, Counclon at a meeting of the above society and for-spondentisaware)ofincreasingtheRoad, Coventry. applied voltage by means of local poten-AT a meeting of the above association on Nov. warded to the various officials immediately 1st, Mr. Sidley gave a short address on, general concerned : tial.I :did not show potentiometers andsubjects connected with wireless telegraphy. "That this representative meeting of thebatteriesin my diagramsinordertoMr; Sidley commenced his address by an appeal society views with the gravest apprehen-simplify matters.I should like to pointto all members using reactance to revise their out that a stable crystal such as carborun-circuits with a view to bringing them strictly sion the inclusion of condition No. z on within the P.M.G.'s regulations, both on their thebroadcastlicence; holdingthatit dum, in a well -designed detector, shouldown account and with a view to avoiding establishes a monopoly of the worst type,rarely require adjustment. annoyance to other listeners -in by causing that itisa' menace to both the industrial I should also like to mention that whichoscillation of their aerials.He pointed out and the scientific sides' of Wireless, andit seems I did not make clear enough inthat the prevailing practice of coupling the re- my article, that the "multi -crystal circuit "ception coil to the aerial coil was forbidden, and, that itis a gross and unconstitutional in- that the only permissible arrangement was to terference with the liberty of the subject."was only a suggested line for experiments,couple the reactance coil with a secondary coil W. F. EAGER, Hon. Secretary. and was not a full tested instrument. of a closed circuit inductively coupled to the R. W. E. (TamwortIV. aerial coil, and that although this: might seem Crystal Reception to involve additional difficulty in tuning, yet SIR ,-I havereadwithinterestthe The"Work"Handboek"Wirelessin practice the difficulties were not nearly so greatasmightappear.Alsothatwhile letters relating tocrystal receptionthat,Telegraphy and. Telephony ",is :the bestcritical tuning was as- necessary as ever in the have appeared from time to ,time, in, thevalue obtainable. secondary circuit, Considerable latitude was mateur Wirelesc 596 DECEMBER 2,1922 obtained in the aerial circuit, and in generalby means of contributions in the form ofWoolwich, showed the practical application of with a given coil in the latter the aerial con-money or apparatus. the lecturer's remarks. denser might be varied throughout its whole range without losing a station which has been Manchester Wireless Society East London Radio Society tuned -in. Hon. Sec.-MR. Y. W. P. EVANS, 2, ParksideHon. Sec.-MR. W. G. SIMMONDS, 6o, East Road, Princess Road, Manchester. Ferry Road, E.14. Portsmouth and District Amateur ON Nov. 1st Mr. Y. W. P. Evans gave his firstTug secretary of this society will Cordially Wireless Society of a series of elementary lectures intended forwelcome intending visitors and do everything Hon. Sec.-MR. R. 0. H. Cor,E, 34, Bradfordthe novice and dealt thoroughly with simplein his power to make them enjoy their visit. Road, Southsea. crystal circuits and also combinations of crystal A MEETING of this association was held onand valve.All technical matter was entirely Bromley Radio and Experimental Nov. 1st.The speaker for the evening waseliminated, and the various actions explained Society Mr. Harrold, A.M.I.R.E., his subject beingin everyday language much to the benefit andHon. Sec.-J. P. CROOME, 26, Wendover Road, " Wireless Telegraphy, Telephony and Broad-interest of those present who were just takingBromley, Kent. casting."Unfortunately time did not permitup wireless experimenting. AT a meeting of the Society held on Nov. 13th, Mr. Harrold to go as fully into the subject as Mr. Allen demonstrated and explained his five - he wished, but he conveyed to the membersHornsey and District Wireless andvalve receiving set.The H.F. valve is arranged the system of the earliest forms of trans- Model Engineering Society with tuned anode circuit, and he showed with mitters. Mr. Harrold explained what civiliza-Hon. Sec.-MR. H. DAVY,134,Inderwickdiagrams the functioning of this and other tion owes to wireless telegraphy, and althoughRoad, Hornsey, N.S. parts of the apparatus.Telephony and music at the present time wireless is being boomedOn Oct. 23rd a short lecture was given by Mr.specially transmitted by 2 L W were after- by the daily press, in a few years time it willHunting on " The Morse Code," dealing inwards successfully and clearly received on a be a part of our daily existence. detail with its many and varied uses. loud speaker. Thames Valley Radio and Physical Bromley Radio and Experimental Streatham Radio Society Association Society A LECTURE meeting of the above society was Hon. Sec.-ERIC A. Rocuas,17,LeinsterHon. Sec.-J. Fmmussox-Citoomn, " Cowrie,"held on Nov. 8th.After the routine business Avenue, East Sheen, S.W.I4. Wendover Road, Bromley, Kent. had been carried through, a lecture was given Fur,r, particulars of this society will gladly beAT a meeting on Nov. 1st the secretary statedby Mr. A. 0. Wood, the subject being " Tuned 'sent on application by the Hon. Secretary. that the present meeting place had been (Continued on tage 598) secured as a permanent headquarters and that Hackney and District Radio Societythe future meetings would be held there regu- Hon. Sec. MR. E. R. WALKER, 48, Dagmarlarly on every Monday at 7.3o.He then intro- " Piano -tuning and Repair"is an im- Road, Hackney, E.0. duced Mr. L. Stopes (chairman of the Society), portantarticleinthis week's issueof AN informal meeting of the abovesociety waswho gave an interesting and instructive lecture " Work " (3d.) Otherarticlesare : held on Nov. 2nd. The first unit of the society'son " Primary Cells and Accumulators."The wireless set was installed.It permits of thelecturer described the various types of cell," Making a Leather -covered Footstool," use of valve or crystal detection.Furthertheir chemicalaction,and their use with" Hints on GraftingSoleson Boots," Unitsarein courseofpreparation.Withspecial reference to wireless purposes.The" Wrought -iron Boot -scraper," " Bedroom the aid of a 3 -valve Mk. III L. F. amplifier,second half of the lecture was devoted toCurb and Fire -screen,"" Mending Pots kindly lent by a member, telephony was verysecondary cells, both the Plante and Edison well received.It is worthy of note that theform being dealt with, and charging metbliodsand Pans," "A Fitment for the Scullery," society's .set is as far as possible being builtdescribed. A representative collection of cells, " Close -annealing Furnaces," " Metal without recourse tothe ordinary funds butkindly loaned by Messrs. Siemens Bros., ofDraining Rack for Photographic Plates."

BROADCASTING RECEPTION SETS ONE VALVE SET COMPLETE FOR WORKING, £7-10 - 0 INCLUDING ALL ACCESSORIES G. P.O. Prov. No, 1027. DESCRIPTION Single valve, mounted on polished I -in. ebonite panel with vari- able condenser, smooth acting resistance, grid leak and condenser and all terminals clearly engraved in white, in a mahogany polished cabinet, g in. by 5 in. by 5 in. ... £ 3 - 15 - 0 A TAPPED COIL for wave -lengths up to 90o metres with 2 Terminals for coils for any higher wave -lengths. The coilis enclosed and the tappings are brought out to an 8 -way switch mounted in the front of the cabinet.

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BEGINNER'S GUIDE TO WIRELESS Fxplains inplain, everyday language, everything MOMDROMOMEI beginners wish to know about Wireless Telegraphy. HOW TO ERECT, CONNECT, AND MAKE J. L. CART'WRIGHT gco all the apparatus required for reception of telephony or morse. and full instructions and diagrams tor making coils, tuners, and WORK 24, London Road, Manchester. complete valve and crystal sets.112 pages, price V_ post free Phone:. CENT SAXON RADIO CO. (Dg.), South Shore, BLACKPOOL HANDBOOKS 4200. " STER 32 page Catalogue of Wireless Apparatus, 3d. post free. Works-- BERRY STREET II

IIII DO YOU READ PRACTICAL BOOKS ? The best See Cassell's Listof Technical,Practical and Money -saving Books. A p.c. will ensure your receiving it. series of Practical CASSELL & Co., la Belle Sauvage, LONDON, E.C.4. Books for Practical As our special offer of 'PHONES AMATEURS ! is now closed, we are offering Don't Work in the Dark. Men CONDENSERS You cam acquire a thorough knowledge of the Scientific Principles which complete (complete and parts) at consider. govern the working of your apparatus quickly and easily by our system. 2961 free ably reduced prices.Get our lists PLEASANT LESSONS BY POST AT YOUR LEISURE. from :- -3d., post free. Our Course of individual tuition is certain to appeal to you, whatever Our Standard Prices for 'Phones are now - previous knowledge you may haveorif you have none. Among our students we number highly trained -scientists with University Degrees, as 11 140 ohms .. 30/-

II well as those with no scientifichdowledgewhatever. 4000 ..32/- Special fee for the Course -30/. cash, or 6/A upon enrolment and five

monthly payments of 5/., 8000 ..331- CASSELL & CO. Sysc.ial lie //cede. THIS IS JUST THE THING YOU NEED -BEGIN TO -DAY Limited irrite,opfualarzieuTars 10 - La Belle Sauvage J. CORSTON SINCLAIR &Co., THOS. BARTON &Co., THE NATIONAL INSTITUTE OF APPLIED SCIENCE, LONDON, E.C.4 47, Waterloo Street, The ElectricWorks, 3, 5 & 7. OLD QUEEN STREET, LONDON, S.W.", Glasgow. Blackburn. EMTIOPMEMEM DECEMBER 2,1922 etitautit-Wiretes3 598 CLUB DOINGS(continued front page 596) Anode Circuits."Mr. Wood gave details of his new " Vim " apparatus, and after the lecture gave a demonstration with it.The nextlecture " meeting is on Dec. 13th, when Mr. C. H. Roddis will give a demonstration of Transmission and Reception of Infra -red rays. Leeds and District Amateur Wireless Society HALL' Hon. Sec.-MR. D. E.PETTIGREW,37, Ilex - borough Avenue, Chapeltown Road, Leeds. WIRELESSACCESSORIESAT the general meeting held on Nov. loth, Mr. G. P. Kendall, B.Sc., gave a paper on the subject of" Some Gadgets of a Faddist." HIGHEST QUALITY LOWEST PRICEMr. Kendall kept the meeting highly interested for more than an hour, with explanations as to the use of innumerable gadgets which were SPECIAL OFFER! embodied in his experimental receiving in- stallation.Devices to ensure security of an aerialto maintain an efficientearth were "Dispatch, 4,000 ohms examined closely.Paying 'Articular attention to preserving valves, Mr. Kendall submitted by return,", various means to prolong the life of a valve. BRITISH HEADPHONES Switching arrangements of circuits enabling a OUR LATEST BATCH Very Light. Beautifully Finished combination of valves to be used were ex- plainedbrieflyandclearly.Manyother (COMPLETE WITH CORDS) gadgets including smoothing devices for rough DARLINGTON, anodepotential,shockprotectors,vario- 20/7/, November, 1922. meters, use of potentiometer for regenerative Messrs. Hall's. purposes, plugs and jacks, etc., were described DEAR SIRS, 1916 and various components submitted tothe ..."lain greatly satisfied meeting for examination. and pleased with the articles POSTAGE 9d. already sent." W. H. S. Hornsey and District Wireless These phones, sold almost exclusively elsewhere at 35/-, will Society HERTS, be supplied at 19/6 (below cost price)to allcustomers DAVY,134, 20tkNovember,1922. purchasing within the next fourteen days. Hon. Sec.-MR. H. Inderwick H all's. Road, Hornsey, N.8.

DEAR SIRS, " A MEETING of the above Society was held on . "All the 'goods are to GUARANTEED GOODS Nov. 3rd.A lecture was given by Mr. H. J. my entire satisfaction," etc. Pugh, who demonstrated a crystal detector A. BEADLE. Value with Quality. DISPATCH BY RETURN VARIABLE CONDENSERS: and a -valve amplifier.Persons desiring to Capacity Complete Mahogany join a society in the above -mentioned district CHESHIRE, Parts Cabinet should write to the secretary for full particulars. 19/11,1'22. .001 71- ... 3/6 Hall's. .0075 ... 6!. . ... 3/3 Lambeth Field Club and Morley DEAR SIRS, .0005 ... 5/3 3/- . "Goodsreceived safely .1...... 2/9 College Scientific Society ... 2 6 and amvery pleased with same." . Hon. Sec.-F. W. LING, Physics Laboratory, B. 13. Ebonite top and bottom, 1/6 pair extra Morley College, Waterloo Road, S.E. Intervalve Transformers.-Ratio 5 to 1 12/9 ON Nov. 11th Mr. R. F. Cosser gave a lecture MANCEIESTER, Crystal Sets . 15/-, 35/-and £3 before the members of the above society en- 14111/22. Aluminium Vanes ... Id,pair; fixed andmoving, doz. 6d Hall's. Spacers, large,3td,doz. ; small, doz. lid titled " The Making of a Two Valve Set." DEAR SIRS, Ebonite Knobsfor centre spindle ;each, 2d., 4d. and Sd Aerial Wire,100 ft. in length, 7/22 copper... 2S Oldham Lyceum Wireless Society "We thank you for Valve Legs,with nuts and washers ...each let prompt delivery," etc. A. V. W. Insulating_Sleevingyard 44d Hon.Sec.-GRAHAMHui,BERT, ESQ., 16, Two Coil Holders,solid ebonite mounted on mahogany... 5/- South Hill Street, Oldham. PAISLEY, Three VP 9,6 Crystal Detectors,adjustable inevery way, turned brase PARTICULARSof this society can be obtained Scotland. 210 on application being made to the secretary. Hall's. Slider Rods,drilled 5d DEAR SIRS, Instrument Wire, all gauges. ..."Safely received Er graved Ivorine Scales, 0-180 4d parcel.Delighted with quality Filament Resistances, splendid value ... 2/4and 2/9 ANNOUNCEMENTS of contents,"etc. R. B. E. SwitchArms,complete with knob, collar, nuts,ete.,10d.and 1/6 Valve Holders 9d., is.and 1/6 Amateur Wireless andEleotrics." Edited by Crystal Cups ..plainId.; 2screw2d.; 3 screw 3d Bernard E. Jones.Price Threepence.Published on All originals are at our office, and Large Terminals, all types.. Extraordinary value, 2d.each Thursdays and bearing the date of Saturday imme- can be seen on request. with nutand washers, 19doz.Smalltype ...each 1d diately following.It will be sent post free to any Contact Studs, t x 9,with nuts...... doz. Sd part oftheworld -3 months,4s.6d. emonths, 2 in. porcelain.Reel, shell or egg 'type ... Insulators, each 3d Bs.gd ;12 months,17s.6d. Postal Orders, Post BrassNuts. 2B.A., 4 B.A. and5B.A. doz. 3d Office Orders, or Cheques should be made payable Ebonite Sheet. cut toany size... 36 to the Proprietors, Cassell & Co. Ltd. Fixed Condensers, any capacity 1/3 Grid Leak Condensers 2/9 General Correspondence is to be brief and written Ebonite Slider Plunger complete ... 5d on one side of the paper only.All sketches and Mica, 4d. large sheet.Copper and tinfoil, 8 in.wide, foot 4d drawings to be on separate sheets. Crystals, Bornite,Larborundum, Galena, Silicon ...each 4d Contributions are always welcome, will be promptly 1/. considered, and if used will be paid for. Hertzite 1/9 Communications should be addressed, according to "Dispatch by return" Screwed Brass Studding, 2 B.A., 4 B.A. ... foot 4d theirnature,to TheEditor,The Advertisement is no idle boast. InductancesWound 22/24 gauge wire ... 3/6 Manager or The Publisher, "Amateur Wireless;' Our Stock of Wireless Orders ur der 30/- kindly remit ?male posture La Belle Sauvage, London, E.C.4. Equipment and Accessories is such that we can supply Balance refunded if excess sent. Send for FREE Catalogue every Wireless need at once and at lowest prices. If you TRADE DISPATCH do not see what you want SUPPLIED BYRETURN in our list, please write us. HALL'SREGENT 1282 71, Beak Street, Regent Street, London,W.1 Between Piccadilly Circus and Oxford Circus Electsics Buses 3, 6,12, 13,15, 32, 51, 53, 59 and 88 pass Querist's Coupon Available until Saturday, Dec, 9, 1922 DECEMBER 2,1922 599 entateur WIRELESS PARTS JIIIIIIIIIIIIIDr. J. A. Fleming and ACCESSORIES at F. R. S. MA NUFAC7 URERS PRICES = Terminals, solid brass, knurled, large 2/- doz.: gross21/-

15/. P s s small THE INVENTOR OF THE VALVE Valveholders, best finish' ... each 1;1- Porcelain Insulators f t 6d

Filament Resistances, with special stop stud 4/- Who is a well-known writer in Brass Road, square, l3 -in. 6d Slider and Plunger...... doz. 7/6 THE WIRELESS WORLD & Switch Arms, best Ebonite Knob, 4 -leaf contact each 2/6 RADIO REVIEW is now con- Contact Studs...... doz. 1/- 100 ft. Aer al Wire, 7/22s best copper, enamelled ...3/11 tributing a series of articles entitled Crystal Detector, mounted on ebonite base, ebonite handle, universal joint, heavy brass terminals ... each 4/6 1- Accumulators, 4 volt 40 amps...... 20/9 I 29/6 ELECTRONS Volt and Ammeters, Flush or Raised Fitting:- Plated ... .. each 10/6 B ack Enamel ... 10/ - ELECTRIC WAVES SPECIAL TERMS TO THE TRADE AND We shall be glad to quote for all components of the first quality at equally low prices to the above selection from our list.Every article WIRELESS TELEPHONY tested before leaving our Warehouse. Money returned if not satisfied. Terms : Cash with order.Orders over 201- carriage paid 5- For a short period only we are offering which covers the whole field of HANDY BENCH VICE WIRELESS TELEPHONY TRANSMISSION Specially suited for the Wireless W ork- irf: including the principles and appii- shcm. 2 -in.jaws, allsteel. Sheffield make.The tool you have cation of the Thermionic Valve. been looking for. Carr. paid U El The subject of Valves and their appli- The ABRO Motor Company cation is too great to be completely dealt WIRELESS 331 AL. It IVX .F-: 1\1' 'X' with in one article. a144 and 186, London Road, Manchester WORKS :73 and 75, Downing Street and Hague Street. 'PHONE Central 6149 The first article appeared in the Oct. "N 7th issue (No. 164, Vol. XI), and is con- tinued each week. Since the commencement of this series, overfiftypagesof the WIRELESS OUR PRICES SIMPLY STAGGERING WORLD AND RADIO REVIEW nave = been devoted to thoroughexplanations, E Buzzer Sets complete with Switch Arms, heavy type 2/3 -7 which can be easily grasped, and which a Ear -piece, Tapping Key, Buz- = Dr. Fleming has personally written. E Large Spacer Washers _ zer, Induction Coil, in case 7/6 per doz...... 4d =- (Postage x/- extra.) Small Spacer Washers ti As aresult of the introductionof ..;Single Ear Phones per doz...... 3d===: Broadcasting, thousands are seeking a lucid ' Eso ohms) ...... 2/9 SwitchKnobs xiDia. explanation of the principles of Broadcast- Brass Formers each 216 Knurled Edges, Tapped 2 BA =- ing and how it is done. The exact answers t--:. 3, 4, 5 or 6 each Brass Nuts, 2, ...... 2d will be found in these articles. BA. . per dozen3dFilament Resistances, 2 BA 12"ScrewedRods ea. 4d best quality ,.. each 2/6 There have been many contributions to Brass Rods, 13" X /a" X i " Aerial Wire 7/22 per too ft. 3/3 -2- each 5d wireless literature dealing with the subject ' ' Aerial Wire Silicon, per ---L. Condenser Vanes per doz. 6d too ft...... 2/6 of Wireless Telephony, but never before LI Contact Studs with Nut and Lightning Arresters each 2/0 has it been treated in a manner so well cal- = Washer per dozen 6dValve Holders with nuts andE culated to absorb the attention and interest Copper Foil 4" x ooz ; lb. 2/8 washers ... each 1/0 TE1. of every class of reader, Crystal Detectors completeValve Legs with Nut and= with best quality Crystal 3/6 Washer . each 2d Remember =ValveCrystal Cups, Pins each 2d &with 6d nut, each 2d -.-ti Crystal Detector Parts Ebonite Sheets, 41 thickness If you want full information covering ==..... per set ...... 1,9 any size cut ; per lb. 4/6 the whole field of Wireless Telephony -s. Egg Insulatorseach 3d E Terminals, small or medium, Transmissionreadthesearticlesin: = or per dozen...... 2/6 withnutand washer,per Shell Insulators, each 7d dozen...... 1/6 =nMica, large,3"x 2 r ... each withldTerminals nut and E Mica Washers per doz. 3d washer, per dozen, 2,0 Switch Arms, best quality Centre Condenser Rods, 5 The Wireless World F., each ...... 1/0 each from ... 3d to 1/0 and Radio Review

E--2. CASH GEORGE PALMER WHOLESALE Of all Newsagents and Booksellers REFUNDED 47, GERRARD STREET. LONDON, 11/.1. TRADE P. PRICE 6d. EVERY THURSDAY ;.=-. IF NOT Mamie film LONDON HIPPO- SATkFIED DROME and DALY'S THEATRE SUPPLIED :7-71 E7Iiimmiluutilimiliffilituumillmluilimmiliiiimintuumuuunimiliillllilllllllillfllllllillllllllr FillIIIMIlliiii11111111111111111111111111111111111111191111111111111111I1111111111111111111111111111ifilliffill111111111111A '0 =Uzi' Wireless 600 D7CEMBER 2,1922

rai'a' 'a a a ,IAVA**11,'ILLSIAIEI'llaKIILOAIMIMAJIgg[IMEIKC4EMI--CIE1 111 1111041-1g=10=IMOMDMOEIDIAtalg 1-

L*: El fi. is HULLO EVERYBODY! . _ Do YOU Know US ? If not, why not ? COMPARE PRICES ! COMPARE QUALITY ! ! Complete Sets of PARTS for Making Variable Condensers

Approx. No. of Everything ready to assemble and consist of the following :Accurate Capacityre Plates Price Aluminium Fixed and Moving Vanes, Large and Small Spacer 'Washers, Microfarads Centre Square Spindle (Screwed Ends 2 BA), 3 Side Rods, 12 Nuts and 12 Brass Washers (2 BA), Pointer -scale 0480, Terminals, 3 Bushes, '0015 85 10/. Spring Coil Washers. Best Quality Knob with 2 BA Nut in Centre. 1101 57 7/6 ALL HIGHEST QUALITY GOODS '00075 43 6/9 '00J5 29 5/6 EBONITE TOPand BOTTOM PLATES SUPPLIED (Drilled) Free of '0003 19 3/- Charge with 0002 13 2/3 SETS:'0015,'001,'00075,'0005 '0001 7 2/. (Ifwanted foranyother set include another1/-) Vernier 3 1i9 Postage, Packing,etc., 11- per set extra Packing and Postage for 2 sets, 113 UNSOLICITED TESTIMONIALS A.J.P00K, Esq., SYDNEY J. ASHWORTH, Esq., W. J. CORLESS, Esq., 101, Day's Road, 9,Paradise Place, 5, Whatman Road, Barton Hill, Stoke, ForestHill,S.E.23. 2/10/22. Bristol. Devonport. Ireceived theset of condenser parts quite 17/11/22 13th November, 1922. safely and thank you for the careful packing. Enclosed 6s.6d.for .0005 condenser parts. The quality, price, and the dispatch of your As regards the parts themselves, they fitted Two I hadpreviously(.001and.0005)have high-class goods leave nothing to be desired. together splendidly, making a neat instrument, drawn admiration from all my friends. Remark- I am still able to profit by sending to you for and I consider them the best condenser value able value, they say. them,especially when quality is considered. on the market.

ALL the following GOODS POST FREEat the SPECIAL PRICES attached for POST ORDERS ,7f you are not satisfied wit6 value, return goods andwe will refund all e6arges Filament Resistances.Most wonderful value in Good CondenserKnobs,tapped 2 B.A.,at 11mm. Insulating Sleeving, 6 yds. for 2/2.By the wireless trade.Each 216 and 3/6.By 2/.doz. By post,2/8. post, 216.12 yds. for 4/,By post, 4/6. MI Post, 3/- and 41-. Knobs, with brass nut (2 B.A.) in centre, high- Slider and Plunger, 5d.By post, 8d. Switch Arms, with polished knob, bushed 2 BA class quality, 44d. each.By post, 7d.6 for Slider Knob, plunger and 13 in.rod. The lot, nut,laminated blade,springcoil washer, 2/.. By post,2/6. 8d. Cannot be sent by post. nuts and bush,low.and 1/6 each.By post, CrystalDetector,cupsenclosedwithglass War OfficePattern Terminals, complete with 11] 1/3 and 2/1 each. cover, dust proof, 4/6.By post, 5/3. nut and washer, 1/8 doz.By post, 2/2 doz. [11 Crystal Detectors on Ebonite.Simply marvel- Aerial Wire, 7/22 bare copper, stranded,first Splendid Linein5 -piece Terminals, complete lous value.Each 2/-.By post, 2/8. class quality, not a substitute.Price per NIN,'oitsht.nuvt6.and washer, good size, 1/- doz.By El Fixed Condensers, with terminals on ebonite, 100 ft.,2/10. By post,3/10. Priceper .0003,.0005,.001,.002,.003,1/6;by post, Intervalve Transformers.Each, 141..By pot, 150 ft.,4/3.By post, 5/3. ifij..(Low frequency.) 1:9; .004, 1/9; by post, 2s. Reel Insulators, 1d. each, 11d. doz.Cannot be sent by post. Aluminium Vanes, 2 doz.1/-.By post, 1/6. Oojah Basket Coils, 7 in set, 5/- set.By post, Triple CoilHolders, handsome design on A 5/6. HertziteCrystal,per piece1/3and1/6.By Ebonite, 10/-By post, 11/-. Lead-in Tubes, ebonite, brass ends, 9 in., 1/2. post, 1/6 and 1/9. Large Spacer Washers, 3 doz. 9d.By post,1/-. By post, 1/6.12 in., 1/4.By post, 1/8. Pennon Crystal Detectors, 4/..Ey post, 4/9. Small Spacer Washers, 6 doz. 1/-.By post, 1/4. * NEW TRADE LIST NOW READY. WE LICK CREATION ON PRICES AND QUALITY.

To Callers :We Sell All Component Parts CHEAP ! Brass Rods, Nuts, Washers, Screws, Valve Sockets, Valve Pins, Stop Pins at wholesale prices.

We don't sell cheap and nasty telephones. Try our pest French make. Guaranteed quality. 4,000 ohms, 211-, 251- (Double).Single, 4,000 ohms, 10/- El HEADPHONES8,000 ohms, 25/- (Double). Post,1/-. -1

NOTE ! MY terms are strictly cash with order.All orders by oast are respatched at the earliest possible El

moment, as we have great pressure just now on the postal department. S 27.LISLESTREET, Eli M. RA.Y M 0 NT D, .0.2. 'Phone: RIGHT OPPOSITE Gerrard To avoid mistakes, this address is close to

. DALY'S GALLERY DOOR; 4637 Charing X Road and Leicester Square Tube.

At*EiggiN,:i7iFflairairs7T_Ji*NilirgraWIEvKi'Esi-LiNErfilifkillggriiNNKINNNNWNNN NggraigggNEINNDNINNN[lElgg N I DECEMBER 2,1922 601 emateur Wirviess

Your Your Guarantee. Guarantee.

BROADCAST RECEIVING SETS tar (One, two, three or four Valves) "Clear as a Bell" Our receivingsetswill bear the guarantee mark ofthe Postmaster - General, and are fully licensed under Marconi Patents. BROADCASTING EFFICIENT SETS AT REASONABLE PRICES. RECEPTION Full details and quotations upon application. Besides complete sets we supply numerous component parts for those wishing to build their own sets. SETS PriceLists 3d. post free. Advice and assistance freely given. HAMBLING, CLAPP & Co., 110, Strand, London, W.C. 'Phone: Gerrard 81306. CRYSTAL SETS " 00JAH " HIGH FREQUENCY TRANSFORMERS ONE TO FOUR VALVE SETS PATENTED P.O. Licence No. 0124 IN ;; THE U.K. 111,1111'01,°, We have prepared a range of Broadcasting PATENTS Reception Sets con- PENDING forming to P.M.G.'s FIG. Regulations, and ABROAD. manufacturedunder Patentee's Licence. FIG. ,. Reg-, No. 635488 These H.F. Transformers have been designed to meet the growing demand of the We invite applications for our "R "List, giving full particulars and prices. Wireless Experimenter for a cheap and efficient H.F. Transformer. We are also prepared to offer special terms to Dealers in Districts where They were used successfully in the recent Transatlantic Tests. Agencies have not yet been fixed. All Transformers are wound with D. S.C. paraffin -waxed copper wire (affording the highest degree of insulation) of a gauge far thicker than transformers now upon the market. Min. W/L Max. W/L Unmounted Fig. x Fiv. 2 No. r ... 300 to Soo ... 113 319 416 No. 2 ... 600 to1,400 ... 1/6 4/- 416 Postage No. 3 ... goo to2,9oo ... 2/6 51- 516 extra No. 4 ...'1,800 to4,000 ... 3'- 516 61- bia101d3t0116 F7No. 5 ...3,000 to _ 5,0oo ... 4/- 6/6 7/- PENDLETON. A...MANCHESIBEI? GREENSLADE & BROWN, Lansdowne Rd., Clapham, S W.9 Telephones :Brixton 639. Brixton 3251. A NEW RELIABLE RECEIVING HEADPHONES 4,000 ohms, double bands, complete with flex and tags, Selector Switch at 20s. each, post free = Cash with order. Ex stock.Every instrument guaranteed. The ideal Tuning Device-Makes your Set complete and finished-A perfectly THE SOUTH WESTERN WIRELESS SUPPLIES CO., insulated 10 stud switch, contacts covered = 382a, Merton Road, SOUTHFIELDS, LONDON.S.W.18 E and numbered-Fire proof-Advanta- Rillifillillfififififilfilifillfifinlififillfifill11111111111111111fifilfin111111111111fifillifillfifilinlillfill1111111111E geous when Soldering-Difficult to make

but easy for you to acquire. HEADPHONES, 4,000 ohm, English make, guaranteed .. £ 15 0 FELLOPHONE 2 -VALVE RECEIVER, in Oak Cabinet, 4110104, PRICE 416 EACH with Headphones,Batteries,Accumulator, Aeriuland Insulators £90 0 8/6 per pair 2 -VALVE AMPLIFIER, in Oak Cabinet (for loud speaker) £50 0 Cash with Order.Packing and Postage Free o TRADE SUPPLIED SUPER CRYSTAL SET, with double Headphones,Aerial and Insulators . £40 0 47) Superior Resistances, 5).; L.F. Transformers, 21/-; Knobs,Ed.; P'10111111.frl E. & D. MANUFACTURING CO. Condenser Dials, 1/9; Mullard "Ora" Valves, 151-; Mullard Grid 112a, Queen Victoria St., London, E.C.4 Leaks, 5/-; Ebonite Block Condensers, '0003, 2/9 ; Switch Arms, 3/6. F. N. GOWN & CO., Ltd., 31, Upper Brook Mews, Lancaster Gate, near Paddington Station. WIRELESS FOR THE HOME Bp NORMAN P. HINTON, B.Sc. Price Price Written by an Expert for the Amateur, this book is intended as a guide for all who have installed or who contemplate installing wireless apparatus.It tells the amateur how to install the apparatus and 2/= gives the best advice on its selection and purchase. The style is simple, technicalities are avoided, 2/= net. and everything that will smooth the way for the amateur and help him to grasp the main principles net. Of all of wireless, so as to be able, after perusal, to receive messages, etc., has been included. Of all Booksellers Booksellers "WILL BE FOUND INVALUABLE."-The Broadcaster. PITMAN'S Parker Street, Kingsway, London. W.C.2. entateur Wireless 602 DECEMBER 2,1922

444444V44444W444 Notice to Advertisers PORTLAND'S PARTS BY POSTADVERTISEMENT INSTRUCTIONS and copyfor" Amateur Wireless -should beat the office by First Post on FRIDAY morn- "EBONITE "ing at the latest. 6 s.d. s d 4 4 7 X 58 28 02 X 88 ... 65 PREPAID ADVERTISEMENTS. 8 X 6 30 12 X 10 .. 7 6 9 X 6 3 5 to X6 39 Must Sell.Complete crystal set.Nothing to buy. s 12>:5A- 42 171 X 88 ... 96 .1.,cor offer.-Lovell, Wraysbury, BuckS, 9 X 88 410 14. X 12 . .. 105 MakeYour OisnSets. Working drawings sup- 17 X5 53 18 X 18(flair sheet) 12 10plied. Write to-day-Puckle, Buckhurst Hill, Essex. 7 lb. 1 30 36 X 18 1 30 [23 r 28 lb., £4 £5.Nearestoffer. Experimenter'scrystalset, Sono ohm.phones. Particulars,photo sent;seen evenings.-Baecrstock, 70, Strode Road, Portsmouth. No charge for cutting, waste or postage [3 s Delivery by return of post Wireless.-New2 -valve experimental set, complete; worth Lao. -Write Goodacre, Gosberton. l4 s Quality Al. DRILLING, Manufacture, BRITISH Instrument Wire,46 gauge (.0024) single silk wire, Thickness. one Quarter-Surface, Mat ins. 6d.Ilb., post free.-Radi Arc Co.,,, Warwick Street, \V. r. f5 s Accumulators,plates,parts,accessories.Expert repairs.-Barnard, 45, Great Ormond Street, JAMES PORTLAND, [12 39, SINCLAIR ROAD, OLYMPIA. W.14 WirelessDealersthroughoutGreatBritainare stronglyadvisedtostockpartsformaking up N.B.- Mr. Portland Stocks 200 Wireless Partswireless sets. Buy your parts direct from the factory INTRODUCING THE 1111011111111811510011118110012. at wholesale prices.-Newtonia Wireless Factory, 13 and15, Whitcomb Street, London, W.C.z. Huge Purchase of ex -GovernmentWirelessStock. For all wave lengths over 1000 Electric& Ilvaratg: Write for list giving full details.150 -watt dynamos, SCIENTIFIC APPLIANCES oyiicai ; hedgehogcoils,3s.6d. ;loudspeakers, zoo LESS PARTS and Materials at LowestPrices. ohms, 7s.6d. ;1 -in.spark coils,los. ;it -in.spark Carl and see our immerse stock or write for Information and Prices. coils, ass. 6d. ; morse tapping keys, 3s., etc. etc. etc. ULTF-WAV In Centre ef London, To, iu Kur,tunny. SCIENT.FIC APPLIANCES, Three days' approval against cash, or please call. 11 and 29, Sicilian Avenue, London, W.C.1. Writefordetailedpricelistofallgoods.-E. J. AMPLIFIER Galpin, 16, Loampit Ilill, Lewisham, S.E.13, London.[s B.A.Screws, Nuts,andWashers,assorted gross. (Made throughout by Peto Scott Co.) 2s.; list, 2d.-J. H. Bennett, Station Road, Willesden Junction. [17 r 11 -ERE isanew plug-inAmplifierbeirr,CRYSTAL SETS IN CABINET All About Wireless-Sendfor Booklet, 64 pages, offered with absolute confidence after the Complete with 4,000 011MS Phones, Aerial, etc., withmanyillustrations," Wireless Made Easy." most exactingtests. For use onall wave- £4, cash with order. Simple,concise.explanation ofwirelesswonder. lengths over z,000 metres. Without Phones, £2 I Os. 9, ,, How to make andfit up at home.Post free, 6d. Or on easy payments, £1 with order and Ss, per week stamps.-The CityWireless andElectrical Depot No condenser or other critical tuningisrequired- VARIABLE CONDENSERS,any capacity or type. (Dept.J),,7, Hatton Garden, London, E.C. merely plug in and be assured of the best possible results. COIL HOLDERS. CRYSTAL D TECTORS, Five Wireless Sets Given Away!Particulars, 3d.- Made in two styles in solid ebonite throughout, No.z FILAMENT RESISTANCES, INDUCTANCE Ilinks' Wireless Department, Hardington, Yeovil. [zo r for use with one H.F. Valve, and No. a for more than STUD BASES, SWITCH ARMS. etc. TheLatest Invention.Steam rotary engine, reg. one stage of H.F. amplification (inthis case No. 2is Send Stamp for Lists.Our Prices will astound you. patent.The finest scientific working steam engine used as coupling between first and second Valves and Save money by dealing direct with the Manufacturers. ever invented.Is. each, 3 for zs. 6d.-Alan Hitchen, No. r between second Valve and Detector). Trade only supplied on small Brass Parts. Patentee and Manufacturer, Dept.17, Burnley.[22r Wires,all gauges; rock bottom prices.Send for No. !- No. 2 - T. W. HALL & CO., Manufacturers,list.-Empire Wire Company,52,May Road, Gil- tor use with for more than 1 2/6 lingham, Kent. [15 r One H.F. Valve one stage of H.F. 58, HARDMAN ST., MANCHESTER. 8/6 amplification EASY TERMS OR CASH Send 6d. for RADIO ROULET Further reduction. No extra charge for extended payments.I. All Peto Scott Radio Transformers, 15/6 & 20'..Mallard Om Valves 15/..Double showiar ROW to buildup CRYSTAL SETS Headphones, Brown's, S erling's 4,00o ohms, 52/., Mul,ad's 4.roo your own Roesivine Set with Instruments sold ohms, 301.. Best French 4000 01092, & 30/, British 4.000 S and rdiseaRadio Parts. underLicencefrom SPECIAL OFFER ohms, high'y sensitive, 20/. & 22/6.3 way Coilholders, 13/8 is Full description of principles 1716, c wa , 7/6.Single Holder 2/6.Honeycomb [.oils list, price r2 in. coil, double slider, oak base, fixed condenser.Hertzite according to ,avelength.Variable t ondensers, complete sets 5, p .rts, involved in plain language. Marconi Co. detector, complete with 4,000 ohm head phones, aerial and top and bottom, cos 6/.. ono5 6/6. A ccumulator,4 volt ao amps, 17/.1, 32 -PAGE CATALOGUE FREE 0 amps, 20/o, 8o amps.404. H. f. Battery, 30 volt 716,6o volt 15/.. insulators. Cash with order. Polished Mahogany Cabinet, with Ebonite Panel, drilled, for Single 55 /- Valve Set Sby 6, 10., two Vats es, so by 8, 15/6, three Valves n4 by 12, Cash returned if not satisfied.DELIVERY FREE.2.1. and terminals.Terms: One-third with order, balance in sin fortnightly payments. Carriage paid on all orders over 40/.. Money EMANCO. 13, CASTLE STREET,I.ONG ACRE,W returned m fun if not completely satisfied.Other accessories for cash atlowest. prices. EBONITE! ! G. BUSH, 119, Sutherland Avenue, London, W.9. SHEET-i in., 3/6 ;I. in.,5/6 ;2 in., 9/ square foot. Offices and Showrooms : Any Size Cut. Best " t" Quality. Genuine "Brunet" phones. Reel Insulators, 3d. each. Aerial Wire,7)22 Enamel, Extremely sensitive,asusedexclusively by 5/6 zoo ft.Velvet Filament R6sistances, with Knobs and 64, HIGH HOLBORN, W.C.I Pointer, 3!'4 each.Switch Arms, Laminated, 3/3 each. French army and navy, 6 tungsten steel poles Condenser Dials, wills Set Screw, oQ-180°, 3,6 each,High each earpiece, 4,600 ohms, limited number at 25/- Note Transmitting Buzzers, 3/6.Valve Holders,1/3 & Delivery per return.Enclose Postage, balance returned. Houghton's Wireless & Electrical Supplies, Intervalve Transformers. High Street, Blackwood, Non. Guaranteed highest efficiency, suitable for super A PERFECT DETECTOR regenerative sets.Ratio, 41 to r. FOR WIRE CONTACT CONDENSERS, the last word in efficient CRYSTALS CRYSTAL design, aluminium frames, all vanes rounded and polished edges, 4" aluminium earthing plate to DOUBLE BALL JOINT BROADCASTING avoid hand capacity, 3" bevelled and engraved Reg. Design No. 691568 RECEIVER dial .001 for panel mounting, £1. MICKELWRIGHT, Ltd. PASSED BY G.P.O. ACCUMULATORS, 6v. 6c AMP.Celluloid Totally enclosed in highly polished Cases, 37/6, carriage free. ALPERTON, WEMBLEY, MX. Cabinet with accommodation for Phones. Mounted on Ebonite INDUCTANCES, wound 22or24gauge, plate. 12 X 4, 4/6. Price - £2 10 0 BASKET COILS, set of 7,goo/30,00o FRriE SERVICE With 4,000 ohms phonds, too ft. metres, 6/9. Have you any queries ?We answer them FREE. aerial, insulators and lead-in tube. THERIGHTGOODS AT THE RIGHT PRICE Carriage paid U.K.£4 0 0. 3 -COIL HOLDERS, long handles avoiding Single valve sets complete from aerial to earth, £610s. ACCES,SORI/1S.. SIn:.11-1.1'.%1R7+ capacity, 13/6 each. Two valve, £8.Three valve. £11 5S.Pour valve, .St PPL1P D. LISTK.L1.. £14 105. Five valve, £18 10. Crystal Sets,I50s. Lists 25. Our Motto: Every other accessory stocked. Dept. "A" "EFFICIENCY with CHEAPNESS" SEND FOR LIST.--- SIMPOLIA WIRELESS CO., 170, West Green Rd., Tottenham, N.15 .41rje practical wireless"te: C. S. MILLS, PAGET, 32, Glenthorne Road, 135, High Street, Notting Hill Cate, LONDON. Hammersmith. - DECEMBER 2,1922 603 ettiattur Wes Vo*Nr-''el'-'Neo'W1 STARTLING REDUCTIONS Ebonite Condenser Dials; Engraved 0-180° and A RECEIVING SET WITHOUT 'PHONES filled white with Knob, Brass Bush and Set Screw 2'6 Dial only ...... 1/6 IS LIKE A SHIP WITHOUT A RUDDER Aluminium Condenser Vanes per doz. ... 6d. Spacer Washer, small 3d. dhz.; large 4d. doz. Knobs, with 2 BA Brass Inset ...3d. A.E.G. and Haiske Valves for recti- The " Brown " Super -Sensitive Telephones Grid Leaks (enclosed), 2 meg. fying and amplifying (tested) ... 7/6 Grid Condensers ...1 6 Crystals (special selected), Bornite, These Telephones are unquestionably the clearest and most sensitive made, Filament Resistances ...... 3/6 Zincite, Galena, Silicon, Carbor- and, consequently, increase the distance over which wireless can be heard. Crystal Cups with Screw ... undum, Copper Pyrite-, Graphite, Fusible Alloy, per stick .. Tellurium, etc. ... 6d. BROWN'S are recognised as the most comfortable to wear, due to their Inductance Tubes, 12' X 3' ... Egg Insulators, Green .. 4d. extreme lightness in weight and adaptable adjustment.There is no wire- 12' X 4' Reel best quality...... 3d. less headphones in the world to compare with BROWN'S. Hellesen 36 v. Batteries with Tap- xi X8'... pings and Wander Plug... 8 6 Wireless Instruments and parts Sliders and Plungers Essex r5 v. H.T. Batteries... 3/ - manufactured by andbearing the Sq. Brass Rod, xu X r X Ebonite Leading In Insulators 1/6 name " BROWN" can still be bought Enamelled Wire, 23 gauge, lb. Perik on Detectors on Ebonite Coin. with absoluteconfidencein their Aerial Wire, 7/25, Stranded, loo' plete with Crystals 4/- quality, value, and efficiency, because Valve Holders, Screwed Legs "Ubique" Crystal Set Complete "A" TYPE throughout this period of increasing DELIVERY BY RETURN GUARANTEED Postage extra. Low Resistance wireless activityS.G. BROWN, Ltd., have wisely refused to lower wlice Shoun,anns 581 - their high standard of quality. 499, GROVE GREEN RD., THE ESSEX WIRELESS CO LEVTONSTONE, E.11. High Resistance Telephone-WANSTEAD 749. (1 min. from Station, G E R.) 62/- to 66/- IMPORTANT NOTICE.-When pur- chasing BROWN'S, you should see "D" TYPE that the name BROWN is stamped Low Resistance on the back of each ear -piece. GENTS' "DISCOL" 48/ - INUNIVERSAL High Resistance USE, AS SUPPLIED TO BRITISH, H.F. TRANSFORMER 52/ - ALLIED ANDFOREIGN GOVERNMENTS. (Above Prices include cords.) HAS BECOME A ILLUSTRATED CATALOGUES POST FREE STANDARD FITTING IN THE Head °glee & Woks- London Showrooms_ Victoria Rd., NORTH 19, MORTIMER STREET, RADIO WORLD and IS IN ACTON, LONDON, W.3. LONDON, W.I. LARGE DEMAND BY EVERY CLASS OF USER-ASK YOUR DEALER FOR GENTS' "DiSCOL" TRANSFORMER -6/8 EACH. GENT & Co., LTD:, FARADAY WKS., LEICESTER London: 25, Victoria Sr., S.W.r. Newcastle-on.Tyne: "Tangent House," Blackett St. THAT BOOK YOU WANT ON WIRELESS OR ANY OTHER TECHNICAL SUBJECT Foyles have it or will quickly obtain it. 1,000,000 Vols. (Second-hand and New) on Techni- cal and every other conceivable subjectinstock. Books sent on approval.Write for Catalevee log (free) mention nr requirements.Books l'u,chased. FOYLES, 121, Charing Cross Rd., London. BATTERIES 24 -HOUR SERVICE H.T. We make it our boast that every letter received has attention within twenty-fourhours. Send your inquiry along and test ourserviceforyourself. Batteries ELECTRICAL SUPPLY STORES, 5, Albert Terrace, King Cross, Halifax, Eng. for New Lists Now Ready. 24 -HOUR SERVICE -- Valve Sets 24v. 28v. 32v. RELIABLE APPARATUS Type B.K. AT POPULAR PRICES Owing to the demand for these batteries, all orders will be dealt with in strict rotation. CRYSTAL SETS, VALVE SETS, etc. EVERY Prices approximately oneshilling a volt. NECESSITY & LUXURY FOR THE WIRE- :: Ask for Leaflet 4030 ::- LESS EXPERIMENTER. ti Fully Illustrated List of Wireless Goods, post free, 4d. 0,eitaibt, EcL0ENCgNyICALLSINITEA_GDE H. D. BUTLER & CO LTD. ,r Office: BANK BUILDINGS, 222, GT. DOVER ST., S.E.I ieCO., I CLIFTON JUNCTION, 219/229, SHAFTESBURY (Opposite Boro Tube Station). Nr MANCHESTER. AVENUE, W.C.2. Works: CANONBURY, LONDON, NJ Teio'ione: Hop 3029. Teieg.:"Ingenuity, 'Phone London." PRICES AND PARTICULARS ON APPLICATION. entateur Wirekss 604 DECEMBER 2, 022 " LISTEN -IN" ON 7. HE STERLING No. 1 CRYSTAL RECEIVING SET The Sterling No. I Crystal Receiver has been specially designed tor use in con- nection with the Wireless Tele p hony Broadcasting Scheme and is suitable for Immediate a range of about 25 miles. The set comprises: 1. TUNER.-This consists of an inductance which can be varied Delivery by means of tappings taken to stud switches. Two of these are fitted, one for coarse and the other for fine adjustment. A separate coil is provided which can be plugged into a fitting at the back of the instrument (as illustrated) for reception of time signals, etc., from Eiffel Tower. 2. DETECTOR.-This is of the crystal type, requiring no battery, and is designed to give universal adjustment over all parts of the crystal. The apparatus is mounted on ebonite panel and fitted in polished walnut case. The equipment includes one pair of No. R1258 DOUBLE HEAD TELEPHONES wound to a total resistance of 2,000 ohmS the pair. To be obtained from all dealers or direct from - Sterling Telephone and Electric TELEPHONE HOUSE, Co., Ltd., 210/212, Tottenham Court Road, London, W.I. Ti'e,oarantee that all Radio eziSaratm,- sold by us conforms such the. Post- master -Generals Broadcasting Licence. Telephone No.4144 Museum (7 lines). Telegrams:Cucumis, Wesdo, London. Works :DAGENHAM, ESSEX, BRANCHES : NEWCASTLE -ON -TYNE: 9, Clavering Place. PRICE - £7 12 6 CARDIFF :8, Park Place.

: LOW PRICES ! ! ! Wireless Headphones 1111111111111111111111111111111111111111i111111111111111111111111111111M11111111111111l111111111111111111111111111111111111E Purely for the purpose of bringing to your notice our New Show- rooms & Demonstration Lounge, all cur small parts are marked at practicaby Cost Price. Below are a few samples of our prices. THIS High Grade Instru- Moulded Valve Holders,Aluminium Condenser Polished, with Flange and 3 Plates, fixed or moving, per ment fitted with Aluminium screw holes ., ... 6d doz. ... 5d Adjustable Diaphragms is Moulded Polished SliderEbonite Condenser acknowledged by leading with Spring and Plunger 3d Ends ...... 1- expertsto be thefinest ye Moulded Polished KnobsBright Valve Sockets, in. Blind nut inlaid3'd Best Quality 2d placed beforethePublic. Sensitive French Phones Wound to a total resistance of Moulded Condenser Ends with Leads, 4,000 ohm, drillea 541 & 8d 2,00) ohms, their sensitivity is . pair ... . Egg Insulators ... 3d British Made Ditto 21: - equal tomost others on Switch Arms with KnobHeavy Teak Base Boards the marketof 4,000 ohms. complete X 91 x 1: - Specially shaped Ear Pieces Mahogany Boxes,High Class Ditto, 4x 7 x. ... 4d Polished, 9- x 5... 7: - Crystal Receivers (Two are designed so that all outside kinds)... Ebonite Panels, Best Matt noisesareexcluded. Head- finished, g x 6 x I,fit neatly New (ex -Govt. Stores) Brown 2,000 Ohms bands are extremely light and into above bogies 2 - Phones (type A) H.R. 49'6 Ditto, L. K 42,'6 covered with the finest quality Ditto Panels, 5 X 7 x 1 6 POST Telephone Cords, Best FREE Ebonite. Ditto ditto 4i. Make, pair 3,'6

All kinds df Valves, Phones, Valve and Crystal Sets. -..:-.. Amplifiers, and Hundreds of other Wireless Lines. =--- Special Terms to Trade E These aLnird I"; ices are merely to induce you to give us a call.Te;ins nett cash 12--: with e,doc, in: buae sub/Cc-rent forostaev Orders (21 Le and over test ./S.ec.

E11111111111111111111111111911111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111g AT THE The BRITISH DOMINIONS TRUST Ltd, ff. E-:-=- H.V.ALBROW ":2 'P"et4E. . NO.5: Ex., BACK OfUT '="- 56,GEORGE STREET, E_T-.- MAYFAIR 161, New Bond Street, g--- SafRIDCE'S E- BAKER STREET, W.1 E. 5842 FE LONDON, W.1. Phone :Gerrard 3438 ,--111111111111111111111111W11111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111A

Printed and Published in England by CASSELL & COMPANY, LIMITED, Ludgate Elill, London, E.C.4,Sole Agents for South Africa, CENTRAL NEWS AGENCY, LIMITED. Saturday, December s,Tcpa (o5 What the Broadcast Licence Covers (p. 616)

ENLARGED NUMBER

No. 27 SATURDAY, DECEMBER 9, 1922 Price 3d.

SOME OF THE CONTENTS

Amateur Experimental Transmitters Why do Signals Fade ?

Adjustable Headpiece Set Legal Position of the (Automatic Telephone Manufacturing Co., Ltd.) Wireless Amateur

REGULAR FEATURES Regulation Aerials Magnification Units On Your Wave -length How to Obtain a Good Radiograms Earth Correspondence Reaction and the Valve Information Bureau Club Doings, etc., etc. Loud Speakers ematzur Wireless 606 DECEMBER 9,1922

1 i

CONOMIC LE CT R I LTD. ('-MITCHELFONES A Are not a spasmodic production to meet a sudden demand, but have been on the Have YOU tried the market for over three months, and during " XTRAUDION " VALVE ? this period 27,000 have been distributed to thetrade, and consequently we have the latest and best development of not been able to offer them direct to the the 3 Electrode Valve.

retail buyer. RECTIFIES, OSCILLATES AMPLIFIES 1,000 per week are now available, andwe announce

Its Mechanical Construction DELIVERY FROM STOCK makes it a stronger and more lasting

valve than any other. Youpostyourorder,orcallatour The Filament consumes well under premises and get them at once.Think half - an - amp. at 4 volts.Anode what this means to you-you, perhaps, who Potential, 50 volts. have been waiting and are stillwaiting. Its Amplifying Properties are Standard resistance 4,000 ohms, double headgear with wonderful and its freedom from noises double headst raps,comfortable,highlyefficient,

a revelation. Send forDescriptive Leaflet. and foolproof 25/.per pair. 15/- 15/- Special Terms to Traders and deliveries PRICE PRICE that will surprise you. PATENTS PENDING MITCHELLSElectrical & Wireless Ltd.; We publish the most complete Wireless Catalogue obtainable. 36 pages, profusely Postal Address:McDermott Road, Peckham, S.E.15. illustrated, and many usefulcircuitsfor Retail Address: Head Office 10, FITZROY 188,Rye Lane, Peckham, S.E.15. experimental work. Mailed to any address SQUARE, LONDON, W.1. on receipt of four penny stamps. 'Phones: New Cross 1540/1541. Showrooms : Telephone : Branch Showrooms Ze-, W orhs 303, EUSTON ROAD, N.W.I. MUSEUM 1055 TWICKENHAM k)10-GREAT BRITAIN'S GREATEST WIRELESS STORE-4)

"HERTZITE" JAN.15" OUR GREAT CRYSTALFOR BROADCASTING ON THIS DATE SIMPLE TO USE. NO BATTERY REQUIRED WILL APPEAR No. 1 of a Price 2/6 post free GREAT NEW Mounted in our Patent Detector, 5/6,postfree MONTHLY See you get our "Hertzite" and not some substitute JOURNAL "HERTZITE" and " PERIKON " DETECTOR,6/6, post free. Entitled We can give the best Wholesale Terms for all Crystals " MODERN WIRELESS" VALVES :"ORA," " XTRAUDION," " C.V.C.," & "R.M.R." I5/- each iood igicZyt It will beedited by John /Scott -Taggart, F.Inst.P., H.I.R.E.,assistedby RUSSELL-SHAW9 Paul D.Tyeraand E. Red - path, well-knowncon- 38, Great James Street, Bedford Row, W.C.1. tributors to"Amateur Wireless." A good judge of wireless STARTLING REDUCTIONS literaturewill insiston getting this first number. C!!!:111)110116 Ebonite Condenser Dials, Engraved 0-180°and filled white with Knob, Brass Bush and Set Screw2'6 Order from your news- Dial only ...... 1/6 agent. It is publishedby Aluminium Condenser Vanes per doz. ... 6d. RADIO PRESS LIMITED. Spacer Washer, small3d.doz.; large4d.doz. Knobs, with2BA Brass Inset ...3d. A.E.G. and Halske Valves forrecti. Grid Leaks (enclosed), 2 meg. ...1/. fying and amplifying (tested) ...7/6 Grid Condensers ...... 1.8 Crystals (special selected), ,Bornite, JUST OUT Filament Resistances ...... 316 Zincite, Galena, Silicon, Carbor- Crystal Cups with Screw ...... 3d, undum, Copper Pyrite,, Graphite, Fusible Alloy, per stick ... Tellurium, etc. ' ...... 6d. Wireless Handbook & Diary,1923 Inductance Tubes,Is' X 3' ... Egg Insulators, Green ...... 4d. ii it T2' X 4' Reel best quality...... 30.

/9 12° X 5' ... Hellesen 36 v. Batteries with Tap - Price2/6net

8 6 51 I2'x 6' ... pings and Wander Plug...... Sliders and Plungers ... Essex 13 v.H.T.Batteries...... 3 - A completeLetts.Diary with40 pagesofvaluable wireless Sq. Brass Rod, re X r x r... Ebonite Leading In Insulators ...1,6 information and the usual pages ofuseful generalinformation. Enamelled Wire, 23 gauge, lb. ...2/- Perikon Detectors on Ebonite Corn - Aerial Wire, 7/25, Stranded, too' plete with Crystals ...... 4l - Beautifully bound in leather, itwill form an ideal Xmas gift. Valve Holders, yewed Legs " 'Clique " Crystal Set Complete... IS'. Get someone to buy you one. DELIVERY BY RETURN GUARANTEED Postageextra. Obtainable through all Booksellers or direct post free 218 from fiice Shouronm 499, GROVE GREENRD., DEVEREUX COURT. THE ESSEX WIRELESS CO LEVTONSTONE, E.11. Telephone-WANSTEAD 749. (1 min. from Station, G.E.R.) RADIO PRESS LTD9LONDON, W.C.2. (1)0'7

and Etectrics No. 27 December 9, 1922

A PROBLEM STILL FADING TO BE SOLVED nNE of the outstanding problems of theof the communication can the trouble becoming close to the transmitter have the day with which both amateurs and pro-traced.Isitin the receiving set,isiteffect of altering the wave -length. fessional men are faced is the finding of ain the transmitting station, or must we look cure for that very prevalent malady inelsewhere for an answer ?Each shade ofTheories wireless communication known as fading.opinion has numerous adherents, and the A great body of opinion, however, attri- Nothing is more common ; nothing is moreexperts are far from unanimous in theirbutes fading to defects in the ether itself, difficult to eradicate; and nothing is more vie ws. or whatever medium itis by which wire- heartily annoying than the coming and By those who believe that the receiver isless waves are carried.' There is much to going of signals in more or less regularto blame,itissuggested that irregularbe said for this theory,: as ' even the most waves of sound. working of the leak across the grid con-thorough overhaul of apparatus by experi- denser,orirregulardischargeoftheenced men usually failstolocate any Telegraphy and Telephony battery,isresponsible. Possiblefaultssatisfactory explanation of the interruption It was bad enough for the enthusiastat the transmitter which have been men-in the signals. when Morse was the sole mode of conver-tionedarevariationsinthesourceof 'When the apparatus is suspected itis sation, but now that broadcast telephony. ispower, or heat set up- in the valves, caus-almost always some partofthevalve, inoperation theposition becomes moreingexpansionandcontractionofthetransmitting orreceiving,ofwhich the serious, and affects an immeasurably largerplate and consequent lack of uniformity ininvestigator challenges the efficiency, but number of people.It would be hard to dis-the output.It is also thought that personswith the crystal, and also long ago in the cover anything more likely toraise themoving about in the operating room anddays of the magnetic 'detector, one of the choler of a listener bugbears of. an oper- than, after getting a ator'slifewas this charming singer or a selfsame fading. delightfulorchestral EXAMPLES OF UNIT CONSTRUCTION The subject is one selection nicely that needs very full tuned in, to hear the and careful inquiry, volume of sound but it may be pointed graduallydie away outthatthere -is without apparent already proof that in causeuntilitbe- certain parts of the omesalmostor worldthereare quite inaudible. At clearlydefined and such', times theset continuous dead has .a dead feeling - spots through which forafew seconds. no wireless message Such happenings are may pass.Is it not offrequentoccur- possible,and even renceamong ama- feasible,thatwhen tcurs,andt her e Five -part Unit Set (Fleet Radio Co.). the cause of the ex- seems to be no cer- istence of one is dis- tain remedy atthe covered, the problem presentstageof wireless de- of the other will at the same velopment time find a solution ? Sofar,thecauseofthe In some tests.carried out by a troublehasnotevenbeen number of amateurs living in definitelyascertained. Prob- the same town, and within a ably in differentinstances distance of a mile or two of therearevaryingreasons, each other,it was found with but,at any rate,the signals regardtoreceptionfroma ofnostationappeartobe selectedbroadcastingstation absolutely immune f r o that fading was experienced at attack, though-with some approximatelythesame mo- transmitting sets thephe- ment by each of the experi- nomenon seemstobe more menters. Furtherinvestiga- noticeable. tionsalong theselines may In dealing with the puzzle, lead to an understanding of the thefirstquestionthat natur- character of this obstacle and. ally- arises-istowhatstage Four -valve Unit Set (Consolidated Trading Co:1 its subsection.G. A. F. entateur Wireiess 608 DECEMBER 9,1922 IllggEEILIKEELI*132*1:10=I[DilgMMIll*g*ID2CEICEJLIELMTM-_!1*ElE3*E11:1=1****LeiCED*0171*M0* Ill El El El . 111 Amateur Experimental Transmitters . ID LC An Article Describing the Various Methods and Apparatus Used in Amateur Transmissions B CI Pit Li] gEMMEICIMEACI*EIELE0000E00EK310K:IK:1*E.111=CEI Kiii gi=gEgM laali),LF_JA****D1=1 IDIE***INI MANY beginners perhaps think that ausefulinthisconnection.Terminals Knegligible wattage absorbed by the set; its continuous -wave transmitterisex-are for use when transmitting C.W.; whentransformation ratio may conveniently be pensive or complicated; the object of thistelephony is required these terminals areof the order of r : i. The apparatus articleisto show that such a beliefisshort-circuited, and a low -resistance micro-shown in Fig.2will not be suitable for phone is connected to terminals m in thetelephony transmission, but only"tonic earth lead. train," and therefore terminals and K The Morse key for connection inthe should be shorted. grid circuit may be of quite light construc- With the second arrangement a small tion, as the power of the set is so low.

rt INEY 6 LT OO To ti.T. 1i l 0 TE9MINO1.5 Fig. 1.-A Simple C.W. -0 and Telephony Trans- Fig. 2.-Method of Using A.C. Mains for Fig. 3. -Rectified A.C. for C.W. and mitter. H.T. Supply. Telephony Transmission. erroneous, and that most probably a low - The microphone carries the oscillatingtransformer of the"nell ringing "type power set may be assembled. from materialantennacurrent,andthereforeshouldmay replace the filament battery of the inthereader'spossessionwithout anyhave as little metalwork in it as possible;rectifying valve;thisvalve may be an monetary outlaywhatever.Itmust beveryshortleadsaredesirable, anditordinary R type or a special rectifier, such understood,however;thatbeforeanyshouldpreferablybefixedtotheset as a Cossor; its filament must not be fed transmitting set can be operated a trans-instead of being heldinthehand.Iffromthesamesourceasthemain mitting licence must be obtained. oscillatory valve.If there is no In Fig.i, from which all un- electricity laid on in the house necessary components have been KEY and it is not convenient to use a omitted, thecoilLisa small loo -200 -voltdry -cellbattery, double -slide tuning inductance, thearrangementsketchedin of the type used for crystal re- Fig. 4 may be used.It is par- ception, the size of which is un- mj ticularlysuitableforportable important, provided it is capable sets,andenablestonic -train oftuningtheexperimenter's transmission to be obtained when aerialto 440metres. Most Micaorttorst terminals Al and x (Fig.r) are amateurs who have taken up shorted. valve work will have such a coil Fig. 5.-C.W. and Telephony Set for Usewith A.C. The induction coil used must left over from their crystal days, be very small, with a very thick but for those who wish to make one, a coilseveralmicrophonesaretohand,all(comparatively) secondary.The capacity 3 in. diameter by 4 in. long wound full ofshould he tried in turn, as one will usuallyof the condenser across this will depend 22 -gauge enamelled wire is recommended,give distinctly better results than the rest.on the size of the coil ;it should be ex- as this will easily reach the standard 440 - The best type of high-tension supply fortremely well insulated, and large enough metre wave -length with a small aerial. use with this set is the D.C. house -light-to enable a potential of about 40o volts For the valve an ordinary R type maying mains, at from So to 600 volts; itis R.M.S. to be obtained across the anode be used, or alternatively an ES2, B, orpossible that some fortunate amateurs mayand filament of the transmitting valve. AT25;toincreasethepowerseveralhave current at the latter pressure laid on In "tuning -up " these transmitters for tubes of the same type may he connectedfor power purposes, and if so, quite a goodbest results the following procedure should in parallel.The low-tension voltage willrange may be expected.Should the light -he adopted : i. Connect up all component parts with KEY the shortest possible leads, making sure

Fig. 4.-Connections of Induction Coil for Supplying H.T. Current. Fig. 6.-Standard Spark Transmitter. Fig. 7.-Power-buzzer Transmitter. depend on the type of valve, but it shouldingcircuitbeA.C.,thearrangementsthat every connection is clean and bright. be as high as may safely be applied; ashown in Figs. 2 and 3 may be used.TheTerminals IC should be 2horted. low -resistance,close -regulationrheostatsize of the transformer is quite immaterial, 2. Listen in on a wave -meter set to 44c in series with a 6 -volt accumulator is veryas it draws upon the Meter only for themetres, adjusting wave -length by s' (see DECEMBER 9,1922 609. emattux Wireless Fig. and oscillation point, by s2 and It is not intended to go at all thoroughlymay be as described for an ordinary spark filamentrheostat. Unlessthesetis into the construction of spark sets, as thisset above.The best capacity for the con- arranged for T.T.aheterodyne wave -type of transmitter is becoming rarer asdenser is found by trial, .005 mfd. being a meter is required, which makes adjustmentthe numerous advantages of C.W. on the-very usual value.The best value for this rather difficult; _alternatively, a clock may- scoreofefficiency,closetuning,andcondenser is shown by minimum sparking be arranged to tick in front of the Micro-abilityto transmit speech are becomingwith best tone at interrupter. phone, and an ordinary spark wave -metermore apparent. employed. Practical Advice 3.If a tonic -train induction -coil set hasPower Buzzers In conclusion, the author would recom- been assembled, adjust break and reverse In the category of spark transmittersmend to the intending experimenter the secondary leads olce or twice to obtain istheso-called"power -buzzer," whichfollowing : best results. has not in this country received the atten- t. Always use a wave meter. 4. When using rectifying valve, adjust-tionwhichitsefficiencyonvery low 2. Strictly observe the regulations ment of filament brilliancy may be madepowers warrants.The customary circuitappertaining to amateur transmitters. with advantage. arrangement is as in Fig. 7.The buzzer 3. Experiment thoroughly for maximum 5.If using a microphone with "variableconsists of a core, similar to that of anrange with minimum power. damping " device, adjust this for loudestinduction coil, about 6 in.long, wound 4. Speak clearly and loudly, frequently speech on a crystal set arranged near by. with about z lb. of 20 -gauge d.c.c, coppergivingyour"call "when radiotele- If the set should break down from somewire, with an interrupter arranged as forphoning. obscure cause, one of the following faultsa sparkcoil.Such a buzzer willtake 5. Lastly, never rest content with usual may be the cause, and the suspected partabout .3 to .5 amperes at 20 volts from aor ordinary results-always expect your should be tested thoroughly : battery of large dry cells. set to be capable of improvement to such I. Microphone granules fused. Remedy : The tuning inductance, which should hean extent as to make it more efficient than Replace with larger ones. accessible to the clips at almost all points,any other. T. W. 2. Plate potential reversed. 3. Disconnection. *Ell=1:EM*EK:=EICA**ElgYD****DITIll******EY*111[111=1EX 4. Condenser shorted internally. * * 5. Lighting -main fuse blown. - * 6. Valve filament touching grid. 1How to ObtainaGood Earth Fli Sometimes, on this -short wave -length, a iii [0] difficulty is experienced in making a set[i CI oScillate.This trouble can he overcome rilEliCKCKAGIIEIEIKA ElEXIIII**171**INI:s11111E1*IlsLeICIEIXIIIICIER DK' gElifie_OK:lg by replacing the two -slide tuner by two AN earth is necessary for all wireless setsmight not be so successful in another, as pancake coils, each of thirty turns of 22 - before -signals can be sent or received,much depends upon local conditions.The gauge d.c.c.wire wound on a nine -peg anditisimportant thata good earthreader, if in difficulty, can try each of the withaninternaldiameterof former should be obtained,foritcan justas above in turn, or a combination of any,. i% in.A very small variable condensereasily be the cause of poor signals as aand note which gives the best results. .00015 maximum (notexceeding mfd. bad aerial can.Great care should there- Itshould be borne in mind that an capacity) is used to tune the aerial.Thefore be taken to make sure that the earthearth should be made in a place where windingsofthetwocoilsshouldbe arranged to run all in one direCtion, andconnection is a good one. thesoilisas moist as possible and not the coupling between the coils should be in dry places.For that reason the water - isusually a very good one, tight but variable. pipe earth AERIAL becauseitis bound to reach damp soil Fig. 5 showstheconnections when Fig. 1 -Earth Arrange- using these coils and rectified A.C.Any ment for Spatk Trans- somewhere. other circuit required may he arranged, of mitting. The connection to the sheet of metal, if course,byreferencetoprecedingdia- EARTH in suitable damp soil, should prove just grams. as satisfactory as the water -pipe..The net- work of wires spread out and buried under Itis recommended that the apparatus the soilor grass can also prove a very described above be mounted on a base- AERIAL satisfactory earth, for there is usually a boardof ample size -ratherthanina fair amount of moisture under grass. asthe experimenter will prob- cabinet, I ig. 2.-Earth Arran:e- The metal gauze mat lying on the grass ably, when he has gained experience with meat for Cont:nuous- EARTH is more or less the same as the network of these simple circuits, desire to make im- viave Transmitting. provements, such as replacing the present v// z wires just described. tuning arrangements by coupled circuits The reader must- remember that in gas, with separate reaction coil, or elaborating There are several methods of makingpiping there is often a coating of paint the radiophone into a choke -control set. an earth, and one of the following can bein the -joints which may greatly reduce the made use of wherever the reader may beefficiency of the earth, and then there is situated : theriskoflightning,thelikely conse- Spark Transmitters (i) A connection made to a water -pipequences of which do not need to be men- To turn from these valve circuits to the(preferablythe main feed pipetothe interesting,thoughfastdisappearing, tioned. cistern) as near the ground as possible. In some caseswater -pipes may have spark transmitter, we find that the usual (2) A sheet of metal about a yard square arrangement of circuitisas inFig.6, painted joints, but in the majority of cases buried a few feet deep in the ground. the joints are soldered. where L is the tuning coil, of about six (3) A network of wires buried under the turnsofcopperstripwoundpancakeground or grass. It may not be known to some that the fashion with in. between turns, and with best place for the earth for transmitting, (4) A metal gauze mat laid upon theemploying methods 2, 3 or 4, is for it to a mean diameter of 6 in.; C is a very well -grass or damp soil. insulated condenser of .0025 mfd. capacity; run paralleltoand directly under the s the spark gap, variable up to Y2 in.; ICSelection aerial(Fig.i)if using spark sets, and an ordinary induction coil, of which iis I have enumerated them in the order inparallel to the aerial, but running behind the break; K a Morse key with heavywhichIshouldselectthem, but whatit (Fig. 2), if using continuous -wave sets. contacts; and B the battery terminals. would provesatisfactoryinoneplace C. E. B. amateur Wixetes3 610 DECEMBER 9, :022

IAlaia,f*_'_ L[:1:K-1.:E.E11.1..D:Ki7e,!.Fiirwiir.,., . 4110:10 ]1:11=11i-jgEl511illg 5171111 1-g How Reaction All About the Valve.-VIII Takes Place tRIACIAAAgDIEIYCIA*EiILIECILCIDADIJALAIDAAACJA.IJALICEITILIDDfillilLICIADFCTIRECIC10111111EligEMKIgilLIAIEmi IT should be mentioned that in the casein producing the regenerative action de-A Simple Explanation of soft tubes, such as the Round valvesired. A simple way of viewing this action is and the early Audion type, a small con- When the coils AB, Fig. 15, arc looselyto, regarditas a mode of lessening the denser inserted in the external grid path iscoupled together; the first impact of signaldamping of the applied signals.Itis sufficientto ensurerectification withoutenergy upon the .aerialis transferred toobvious that when a signal "impulses" the the use of a leak resistance.In this casethe grid.Suppose the first result to betuned circuit BC the resultant oscillation the grid charge accumulated as the resultthat the grid voltage is made more posi7should persist indefinitely ifit were not of an incident wave train is relieved bytive.This is reflected in an immediate risefor the, reactance or resistance of the cir- being transferred to the positive ions ofin the value of the plate current, which incuit itself, which in actual practice rapidly the residual gas contained in the tube. turn increases the magnetic flux throughdamps out the effect of each impulse.If, the coil A.The new lines of force linkhowever, an electro-motive force were to Retroaction with the coil B, and so induce a transientbe applied in phase with the current and An important step in the evolution of thevoltage which is in phase with the plateequal in value to the product of the cur- thermionic tube was the discovery aboutcurrent.This, on being superposed uponrent and the resistance, the effect of the 1913 of the principle of retroaction.Thisthe existing grid voltage, tends to augmentdamping resistances would be*cancelled, development appears to have been. madethe first effect-that is,it boosts the plateand the implied oscillation would persist, almost simultaneously by Franklin andisurrent upwards, beyond the value it wouldtheoretically for ever, at a constant ampli- RoundinEngland,by Armstronginhave reached without the back -couplingtude.In a retroactively coupled tube the America, and by Meissner in Germany.Itaction. additional electro-motive force so required ( onsists essentially in.4"o linking together is, transferred from the plate circuit to the the input or grid and the output or plateSelf.oscillatIon grid, with the result that the applied signal circuits that they interact by mutual 'stimu- Now ifthe reactionisset below theimpulses are maintained by reducing the Iation until, in the limiting case, the tube damping of the grid circuit. is set into continuous oscillation. A criticalpointisreached when the This new characteristic opened out many transferred E.M.F.isjustsufficientto fresh fields of utility.Thermionic tubes, counteract entirely all the damping effects asgeneratorsof continuous waves, are of the grid circuit.At this point the first displacing the older systems of C.W. and HIGH TENSION signal impulse would set the grid circuit telephony transmitters, such as the high- B c, continuously oscillating. frequency alternator and the arc, owing to This is not desirable in practice when their superior advantages as regards com- receiving damped signals, as it would re- pactness, simplicity, regularity in opera- tion, and portability. sultinasteadycurrentthroughthe phoneswhich wouldpersistafterthe Amongotherthingsthethermionic cessation of the signal itself. generator rendered it possible to equip our scouting aircraft during the war with a Accordingly the regenerative coupling is light -weight wireless telephony outfit set just below: this critical point, so that of the maximum amplificationisattained remarkable efficiency and range.Similarly Fig. 15.-Retroactively-coupled Tube. small- and large -powered valve transmit- whilst keeping the platecircuit respon- ters for C.W. and tonic -train telegraphypoint at which self -oscillation occurs (assive to the impact and cessation of each were rapidly developed, and proved them-where the tube is being used purely assignal. D. ALCASE. selves superior in many respectsto thean amplifier for increasing signals), the (To be continued) various types of rotating -gap, quenched -upward growth of the plate current is ulti- spark, and similar transmitters previouslymately arrested by the impact of the next in use. half -wave of signal energy, which this time Fig. 15 shows a typical circuit arrange-throws the,grid voltage in the negative Regulation Aerials ment for a back -coupled valve as applieddirection. A. CONSIDERABLE amount of uncer-

to receive C.W. The resulting drop in the plate current tainty exists regarding the conditions reduces the value of the magnetic linkagethat must be fulfilled for an aerial to com- Its First Uses between the coils AB, and this time theply with the official regulations.The fol- Before discussing theelectricalactionresulting transient E.M.F. induced in thelowing are the conditions as communicated of such acircuit,itshould perhaps becoil B is in the opposite direction (again inbytheSecretaryoftheGeneral Post mentioned than back -coupling wasfirstphase with the current) and tends to throw Office :Itis necessary that the aerial of used simply and solelyasa means ofthe grid voltage still more negative, soa station for the reception or transmission amplifying incoming signals to a greaterthat the drop in the plate current is againof wireless signals' shall not exceed a com- extent than was previously possible.Itgreater by the effectof this transferredbined height and length of too ft.The was only subsequently discovered that thevoltage. height is regarded as the vertical height ultimate result of the interaction between The dropping current in turn is againfront the leading -in point to the level of the grid and plate circuits was to set thearrested by the ensuing half -wave of signalthe highest point of the aerial, and the whole system into a state of self -oscilla-energy, :andisturned upwards by thelength as the length of the span.Pro- tion.Further, although as shown in Fig.change in grid voltage, and so the processvided the foregoing limit is observed there 15 the connection between the two circuitsgoes on so long as the signal impulses areis no restriction as to the number of wires arises from the magnetic linkage across beingreceived. The neteffectis,of which may be used in the aerial. Authority the coils and B, other means of electriccourse, to increase the energy changes into use an aerial in excess of the standard coupling,suchasbytheelectro-staticthe plate current so as to give -amplifiedlimit is only granted where special justi- action of a condenser, are equally effectiveeffects in the phones. fication is shown. DECEMBER9,1922 611 enutteur \Wireless

pePediectke.gealtavt

For receiving vocal and instrumental items you must have MULLARD "ORA" VALVES to get the best results. Oscillates RectifiesAmplifies. Specially recommended where good amplification is required. The "Ora" Valve requires about 3'8 volts on the filament and 30 volts or over between the anode and filament for efficient results 15/-each IMPORTANT NOTICE The great demandforMullard" 0 R A " Valves and other accessories has compelled us to open much larger works.A greatly in- creased output is now available. The Mullard "R" Valve is now reduced in price from 22/6 to 17/6.

Ra diovaive Glad. e' a° Ao 45, Nightingale Lane, Balham, S.W.12.

zy'c' 111111111111111IIItl I 11111111111111111111111111 II 11111111111111111111111111 1 Il Ii 111 4.s,e O's* c,Z). 4.7 N7 aka,°ocs,C' e b* ° .0 4 c1:- 0 csc, - 0';.* 'D

ADO 7 A.\ MINIM111111 MMAR,2) mlr e

Unprecedented Offer of- Ex-Govt. WIRELESS MATERIAL AN APOLOGY. Owing to the overwhelming number of orders received by us for this Ex -Government apparatus, we have been unabletocope with the tremendous number of enquiries as expeditiously as we would wish. We respectfully ask the indulgence of readers, and assure them that we will reply to their queries at the earliest possible moment. In the meantime we are despatching all orders in strict rotation, and guarantee delivery within 18 hours of receipt. Gs*V.01..r"..eNer4..,,roWfteW`v^'WVAN, RECEIVERS, C.W. MARK III C.W. TRANSMITTERS, MARK III, 30 WATT This set comprises a complete 2 -valve Receiv- For two valves. Complete, with aerial ammeter, ing Set, with a wave -length range of 350 -1,800 platinum -pointed Morse Key, in Mahogany case. metres.The addition of High and Low Tension Wave -length range 300-r,800 metres. Batteries,valves, and 'phones completes the Note.-This set can be conveniently converted entire receiving station.For the reception of intoa2 -valveDetector -Amplifying Receiver. £35 0 Broadcast concerts this set is ideal, the strength and clarity of the signals being absolutely wonder- B MARK II RECEIVERS ful.London readers should take the opportunity Vertical pattern.Can be easily converted to

of hearing this set working at our Showrooms. any wave -length ... £3150 Only 100 left£990 Above, fitted with Variable Air Condenser, Complete with 4 -volt 40 -amp.Fuller Block .0005 mfds., in place of change -over switch £4 150 Accumulator, 6o -volt H.T. Battery, 2 Mullard " ORA " Valves, andpairof Brown " A " HETERODYNE WAVEMETERS. 500- Type Headphones, complete with cords E15 10 0 3,000 Metres For Receiving-without Galvanometer £200 AMPLIFIERS, C. MARK IV For Transmitting and Receiving, containing This instrument is a complete three -valve low- fequency amplifier, and can be used in many Weston Galvanometer .£300 ways without modification. AERIAL MASTS AND EQUIPMENT The C. Mark IV. Amplifier is an improvement on the C. Mark III. (the latter being sold by 15 -feet Steel Masts in Sections, each 2 ft. 8i in., other dealers at f6 5s. od. each without cases), complete with Halyard, Pulley and Stays.Can inasmuch as the C. Mark IV. contains terminals be erected by one man, and are portable.The and change -over switch. allowing the use of the height can be increased up to 3o feet by the use instrument for either High- or Low -Frequency of extra stays ...Per Set Complete£0 150 amplification. 3o -feet DITTO, in SECTIONS, each 4 ft. 3 in. The price at which we areofferingthese (mast only) ...Per Set Complete£0 176 Amplifiers is less than the actual value of the transformerscontainedintheinstrument. SULLIVAN HEADPHONES Limited number only left subject to being unsold. ... £0 126 Complete in Mahogany Case£450 SULLIVAN HEADPHONES INSULATED AERIALS 120 ohms complete with new Telephone Trans - 4o -feet £0 1 0 6o -feet £0 1 6 former (value 25s.) in iron case ... £1 100 ( Kindly note that the above prices do not include Packing and Carriage.Please add, therefore, an appropriate amount to cover this. Any surplus will be refunded. The City Accumulator Co.

1 79, MARK LANE, LOiDON, E.C.3 i j. 'Phone:...4c,ne 1316 li Wholesale and Retail Distributors for Messrs. BURNDEPT, Ltd.Same Trade Discount Allowed as by Manufacturers. AG ENTS. London: H. V. ALEROW, 56, Goorge Street, Baku S.1Vales: SOUTH WALES WIRELESS INSTALLATION Sweet, W.I. CO., LTD., IS, West Bude Street, Cardiff. Glos. BRISTOL WIRELESS CO.,52, Cotham 11,;1, N. Wales, Lanes., Ches. & 1.0.M.: THE " ALL. li Rristol. BRITISH ''WIRELESS MANUFACTURES CO., LID., Le,cest,f : WALTER Rowe, LTD., 96, Granby Street, 18, Vauxtriall Road, Liverpool. Leicester. \\ -..%,,-.....--...... , -"'.....4 /// DECEMBER 9,1922 613 Ontateur Wu-etes

Too Much The Broadcast Condenser HOW many of The news bulletins are not exactly strik-France. T h is, Licence usknowor, ing.There is, of course, the weather fore-mark you, is done 2L 0, 2W P and if we know it, howcast,followedbycricket andbilliardevery evening and 2M T's Burlesque Radiola many of us obeyscores and market reports,allof whichtwice on Sundays, thefirst goldenwill be greatly appreciated by those who by a company A New A Wireless Miracle rule of tuning,do not see the evening paper.But the restwhich receives no Transformer ! whichisuseas of the programme consists too much ofshareoflicence littlecapacityaspolice court news of no particular interest,fees, for the benefit youpossiblycanintheprimaryofand of "snippy bits" of the kind whichof listeners -in who arc not compelled to theaerialtuninginductance? Coilsharassed sub -editors generally use for fill-use hall -marked apparatus.Thereisa areoftenstated,totune from 400to ing up gaps into which nothing else willmoral in this somewhere. i,000 metres with a .om condenser; they fit. You know the sortof thing : 2' * will do so, but every extra degree overBlank Dash, aged 103, has just made a * * about 45 marked by the condenser pointerflight in an aeroplane. A deported tom -cat Perhaps thegreate"st miracle that has means a loss in efficiency.If you wishhas arrived home after a journey of 'minty'ever happened in wireless was announced your set to he really efficient you should notmiles, and so on. by 2L 0 with his 9 p.m. bulletin on -Mon- use a variable condenser in the primary day, November 27th.The entirepro- o biggerthan .0005mfd. TheA.T.C. * 42, grammeofanAmericanbroadcasting should be wired inseries for all wave There is one thing about itall, how-station was heard that morning in Croydon. lengths under i,000 metres.It is difficultever :if you do not like what London isItappearsthatMr.J:H.Ridley,of to_ realisethe almostinfinitesmallnesstransmitting you can always turn on Bir-Messrs. Burndept, was listening -in on 325 of the impulses brought in by the aerialmingham, and vice versa.Birmingham'smetres for American amateurs, when he totheset. Certainly the currentisa transmissions are amazingly good. Thoughsuddenly heard strains of music.Sharpen- million times too weak to light even ahe is three times as far from my aerial asing the tuning, he was amazed to pick up pocketflash -lamp. Thereisabsolutelyis 2L 0, he comes in every bit as strongly.the call letters W J2, which are those of nothing to play with, and if we reduceIt is a pity that he puts on so many gramo-.theNewark, New Jersey,broadcasting the efficiency of the set by adding capacity,phone records.After all, if one wants tostation.For a whole hour he listened to simply because we are too lazy to put on ahear gramophone music one can do sothe programme, every item of which was bigger set of coils., we must not be sur-without using a wireless set.Records un-clear anddistinct.This opens up an prised if we do not get the best results.doubtedly do not sound well in wirelessentirely new field in wireless.At no far transmissions ;one cantellthemina The moral of all this is : Always use the distant time we shall be able to listen in largest possible coils for any given wave-'moment.If the broadcasting stations areour own homestotelephony transmis- length,andtunethem by addingas going to make extensive use of what thesions from all parts of the world. little capacity as ycu can. Americans call "canned stuff" they will not encourage the popularity of wireless. * * * va * * v. * * It is to be hoped that amateurs are not Here isa tip that may save quite a On thewhole,our broadcastingpro- going to take the broadcast licence lying cumber of shillings over the lead-in andgrammes are quite good, but they cannot down.If they make a determined and the earth wire.If you buy heavy rubberedcompare with the Concerts Radiola, trans-combined, effort they, can ensure the modi- cable for the purposeitwill cost frommitted bytheSociete Francais Radio-fication, if not the complete suppression, of 6d. to is. a foot.But there is some ex-electrique, whose station \isat Levallois-the odious condition No. 2 on the back. If, cellentstuffusedbyelectriciansforPerrett, near Paris.Next time you arehowever, they are 'content to do nothing wiring heavily -loaded household circuitslistening -in between $ and 9 p.m., or be-they will have themselves to blame if the which will answer admirably.It ,consists tween 2 and 3 o'clock on a Sunday after-.monopoly, having become _firmlyestab- of seven strands of 18 or 22 -gauge coppe:noon, tune to 1,500 metres, and you shouldlished, proceeds to treat -them as monopolies wire with an insulation whose resistancehave no difficulty in pickingup this station,usually do. is8 megohms.This wire, which. costsfor its transmissions come in very strongly. * 2' * * about 7d. a yard, will do all that is needed. On November 26th the matinee perform- Did you hear that delightful jester, the * * * ance consistedoforchestralpieces,allO.C. Writtle transmission, in his burlesque beautifully, rendered, -by Weber, Mozart,of2.L O's new chimes ?'Twas done, so 2L O's new orchestra is a great feature. Gluck and Greig, a humorous turn by one'tissaid,with two biscuittins and an At theirfirstperformance on Saturday,of the most popular music -hall stars-hisempty soda water bottle. November 25th,they had a succes fon.topical song, with itsreference to Lloy' So many congratulatorycallswerere-Jorge,would have broughtdown any * .5' * ceivedon the"land -line "thatthe French house-and songs and instrumental OverheardConversation :"Yes,isn't announcer had to issue a C.Q. messagesolos by artistes of distinction from thethiswirelessawonderfulthing ! So begging admirers to send postcards insteadOpera and the Conservatoire.EVery itemromantic, too, to think of messages coming of telephoning in order to prevent the onewas a little gem.Not the least attractivelike that through space.My daughter's operator on duty at the exchange frompart of the programme lay in the shortfiancé, a charming man, my dear, always being snowed under.The orchestra's per-chats on the various composers given bysays good -night to her by wireless. He formance of part of the "Peer Gynt" suitethe announcer before the performance offailed to do so the other night and we was magnificent, and the ,dance music t'opieces by them :"Morceau par Weber,couldn't think why until he sent a note which they treated us at intervals musttompositeur al7emand-mais ra/pelez-vous tosay thathisosculationtransformer have set hundreds of couples a -fox-trottingy'aitmoundil-y-aplusd'unsicle!"had brokendown ! " Well !Well ! in all parts of the country. Nothing Hunnish isyet very popular inWell ! THERMION. =fair Wireless 614 DECEMBER 9,1922

To TRANSFOR R PRIMARY FROM 7 11A NSFOME "Amateur kCONDA RY To ThANsFoRrIER Wireless PRitomaY

Ideal Unit ti7 Receiving HT - Set LT The Third Article by Mr. R. W. Hallows on the Construction of a Complete Unit Set, FtHEOTAT Fig. 9.-Under Side of Low -frequency Panel. Fig. 7.-Under Side of 114h -frequency Panel. MOST of those who use multi -valve setsamplifier, a rectifier and one note-magni-place, one-half of each has been filtered will agree thatifthere areto befier-and to add to his set by fitting upout, so that it consists now of either a crest several steps of amplification the majoritysome further high -frequency units ratheror a trough; in the second, the waves have of them should be of the high -frequencythat those which amplify at audiofre-now been marshalled into groups, and, as type.Note magnification, though it givesquency. itwere, fused together,sothat several a much greater volume of sound in the The two types of panels differ consider-hundreds of them combine to produce one receivers, has several serious drawbacks.ablysince their tasks are quite unlike.movement of the telephone -receiver dia- Amongst other things it always gives riseTheradio -frequencyunitreceivesthe phragms. to a certain amount of distortion.This,rapidlyoscillatingwaves --.hatarede- The high -frequencyimpulses may be if only one low -frequency valve is used, islivered toiteither by the secondary ofpassed on in several ways, two of the best not as a ruleserious, butifthere arethe tuning inductance or by the plate ofof which forshort wave reception, the several stages, it may become bad enough aprevious valve.These arecompletetuned plate and -the air -core transformer, to spoil most of one's pleasure in usingwaves,andifthe wave -lengthis400 are shown diagrammatically in Figs. i and theset. There isalso the further dis-metres 750,00o undulations occur in each 2.A third method, the resistance -capacity advantagethattheslightestparasiticsecond of time.When the waves havecoupling,thoughexcellentforwave- -- noise in the set is enormously magnified.passed through the detecting valve theylengths of over i,000 metres, does not give The reader will therefore do well to beginare delivered by it to the note -magnifiervery good results with the shorter waves. withthreepanels-oneradio -frequencyinaverydifferentform.Inthefirst Fortheconversionoftheoriginal

2.-Tuned-ancde Coupling of H. F. Unit to Rectifying Valve. Fig. 1.-High-frequency Air -cored Transformer Coupling.

The photographs Figs. 8 TRANSFORMER SECONDARY and 9 will be referred to TRANSFORMER in the next instalment of REACTION PRIMARY this series.

HOL DE R-

A.T.I. o0 v.

6v - T-

Fig. 4.-Diagram of Coil Holder used as H. F. Transformer. fig. 8.-Photogr,ph cf Law -frequency Panel with Iron -core Transformer. DECEMBER 9,1922 615 mofertr Wireless The panel can now be used with any

kind of two -coil tuning inductance as a ToTRANSFORMER 0 0 complete receiving unit by clipping it to theterminalpanelandattachingthe head -telephones to tite output terminals on PRIMARY theotherside. Those who have pre- viously used only the unaided crystal will SECONDARY

[SPOT be surprised at the increase in both range OUTPUT and volume of sound which follows on the 0 addition of even one high -frequency valve. HT* Great care should be taken to find the HT+) most sensitive spot on the crystal and to INPUT get the pressureof the contact exactly 0 right.To do this you cannot do better HT- HT - than adjust the set to 600 metres, on which T - LT- wave -length there, is always something to hear at any hour of the day or night. 0 When you have made signals as loud as 0 - 0 LT+ possible by means of the tuning induct- LT ance, and the variable condenser of thefig. 5.-Wiring Diagram of RP. Transformer plate circuit,turn your attention to the Panel. detector and adjustitsothat you arepanel in the place occupied by the trans- Fig. 3.-Wiring Diagram of H.F. and getting the best out of it. former shown in the photograph (Fig. 6, Detector Panel. p. 569). There are two main types of trans- High -frequency Panel former on the market to -day, the "plug-in" crystal detector panel we make use of the The high -frequency panel containing a first of these methods, using the basket and the tapped.The former are small valve aloneismost conveniently mademushroom -shapedaffairsprovidedwith coiloriginally mountedfortheaerialwith transformer coupling.A high -fre-four prongs (one pair for the primary and tuning inductance as the coil in the tuned -quency transformer consists of two coils ofthe other for the secondary turns) which fit anode circuit. equal,oralmostequal,sizecoupledinto an ordinary valve holder.Their great Fig. 4 (p. 568) shows the finished panel.'together.The primary receives the out-advantage is their cheapness, for they can The valve -holder and filament rheostat areput of the valve, inducing in the second-.be bought for about 5s. each.They have, mounted asbefore,and two extrater- ary a current which is passed on to thehowever, one serious drawback, which is ' minals are required at the lower ends ofgrid of the succeeding valve. A perfectlythat each covers a very limited range of the panel.These are to take the leadsefficient transformer can be made by using wave -lengths, so that a set of eight or so froM the variable condenser which tunestwo basket coils which are simply laid oneis necessary in order to receive trans- the anode inductance.About .0006 mfd. on top of the other, the upper one beingmissions from 25o to 25,000 metres.If the will be found to be a suitable value for movedaboutuntilthemosteffective set is to be used only for the reception of this 'condenSer. degree of coupling has been found.Withbroadcasting the plug-in transformer will The wiring, which is shown in Fig. 3,this type of transformer itis an advan-answer admirably; but if you wish to be looksatfirstsight rather a formidabletage, though it is not absolutely necessaryable to receive everything that is going in undertaking, but actually it the way of both telephony Mies not present any great andtelegraphy,youwill difficulty,especiallyifthe find the tapped transformer anodecircuit,shown in TERMINAL PAMEI. SECONDARY (Amex:ER much more convenient. iscom- heavy black lines; ,'-,EteL5-,3-RARALLELSWITCH Those the author uses are pletedfirst.Itisa good providedwith a rotary tip when making up any switch and four studs.The of the, panels described in first istuned towave - these articles to draw pen- 1 e n g t h sfrom 200-400 cillines on the under side metres,the second 400- ofeachcorrespondingto 1,000, the third 1,000-3,000, the leads themselves.The and ,the lastto those over

wiring, --havingbeenfirst - - 3,00o. Whichever type it is mapped out in this Way, is - decided to use see that they thenquiteaneasytask; are well made, and remem- further, if at any time tern- berthatiftwoor more poraey changesare made transformers are used, their in the Circuits; the pencilled electricalvaluesmust be lines showing the original identical,otherwisethey positionsof the wires are Fig. 6.-Photograph of Rectifying Panel in Use as" Sin gle-valver." will work against instead

alwaysthereto:act - as., of with each other. guidesandtime-saverswhenthecon- to tune one of the coils with a variable The high -frequency panel differs from nectionscometo:. be remade.-Recordscondenser.Fig. 4 shows how a three -coilthe valve rectifying unit in thatit has ofseveralcircuits,. canbekept- by holder may be -used as a high -frequencyonly the ten terminals arranged in two usingpencils- withdifferentcolouredtransformer,thereactioncoilfrom therows of five on the long ebonite strips. leads. rectifying panel being coupled in this caseThe input or primary side of the trans- With some kinds of crystals it will be tothe secondary of the transformer, aformer receives impulses from the plate found advantageous to place a small fixedmethod which entirely eliminates the riskcircuit of the valve, which makes itin condenser between the detector and theofcausing annoyance toothers byre - some cases rather difficult to mount it so top output terminal; this acts as a block,radiation from one's own set. that the lead to the grid of the valve shall preventing any of the high-tension cur- Either of these improvised instrumentsnot run near that going from its plate to rent from passing through the crystal. can be mounted on thehigh -frequency the transformei.It is important to keep mateitr Wireless 616 DECEMBER 9,1922 these wires as far apart as possible, other-[11*XMYEILIXII7E1*****111EIE*X* facturer, they took the view that the set wise theset may be noisy when high - * could properly be used under the terms of frequency amplification is in use owing to the ordinary broadcast licence.This will El capacityandinductioneffectsbetween A Broadcast LicenceMbe _splendid news for the thousands of wire- them. Care must be takenthatthese less enthusiasts who have been placed in wires are not parallel to each other and FilCovers a Built-upIa stateof difficulty during the last few close together. Li weeks, and also for that body ,of manufac- Fig. 7 shows the under side of the panel,Z :: :: Set :: :: :turers which, since the issue of broadcast whilst Fig. 5 shows the wiring diagrams,0 LI regulations, have simply not known where which is applicable to any type of trans-ci *1 AGICE11=1**0**Ella2:01:110MEk they were. former. the courtesy of Messrs. Peto Scott we 1,alve for Amplification B,-areabletopublishthefollowing Though a soft valve may be used withcorrespondence: The British Radio Manu- advantage as a rectifier, this type will not give good amplification.A really hard Applicant's Letters to the Postmaster - facturers'and Traders' valve, that is one with a high degree of General Association, Limited vacuum, will give by far the best results, "DEAR SIR,-I beg to apply for an ex- WE learn that a company, limited by' but care should be taken toselect oneperimental licence to- enable me to use a guarantee and bearing the above which works bestwiththesame platehome-cnstructed PetoScottinstallationname, has now completed its legal forma- potential as the valve used on the rectify-for receiving at my private residence.-I tiOn. It takes over the members of the ing panel.If amplifying and rectifyinghave already a broadcasting licence, butWirelessManufacturers'andTraders' valves require quite different voltages onrealise that this will be useless for theAssociation of Great Britain and also the their plates, the unit system becomes un-apparatus I desire to use and the field I membersoftheTradeSectionof the satisfactory unless a potentiometer is usedwish to cover." recently -formed Radio Association.There in the anode circuit of the rectifier, since is not much doubt that it will be able to normally the H.T. leads supply the same The Reply do its work in a far more thorough and potential to each valve. "DEAR SIR,-With reference to previousefficient manner than waspossiblefor When the high -frequency unit has been either of the two associations from which: completed it should be tested in conjunc-correspondence,Iam directedbythe itdraws itsoriginalmembers. Its tionwith therectifying panel. Fig. 6Postmaster -General to forwardalicence shows the rectifying panel used alone as afor the reception of broadcast messages,executive council, which will not exceed and to say that, asitis understood thattwenty,alreadycontainsfifteenrepre- complete receiver. The H.F.panelis sentatives of firms every one of which is simply inserted in front of it.You can- you have already purchased your appara- not go wrong in the connections, since thetus, no objection will be raised to its usewell known toreadersofthisjournal. correct pairs of terminals come oppositeprovided thatitwas purchased_ from aThe registered office of the association is each other when the units are placed sideBritish manufacturer, and that it compliesDundee House,15,Eastcheap, London, by side.Itwill probably be found thatwith the technical conditions of the licence. E.C.3; and the secretary is Mr. Charles the tuning of the aerial and secondary in-The requirementsin regard to the Latham, A.L.A.A., A.I.Ar. ductances alters considerably as a high -apparatusbearingtheregisteredtrade Membership of this association is open mark of the British Broadcasting Companyto any British firm in the wireless indus- frequency -valveisadded. As soon as will not in the circumstances be enforcedtry,theannualsubscription being two signals are coming inas wellasitis possible to get them turn to the filamentas far as the set in question is concerned.guineas.The principle of alternative re- rheostats; and adjust them, moving at theI am to add that when this licence is re-presentation has been adopted so that any same time the wander -plugs of the high-newable an account will be rendered byone of a firm's chief officials may repre-, tension battery until the best combinationthe local postmaster.-I am, your obedientsent it in the meetings of the association. of filament current and plate potential hasservant, There arealsoto be honorary members, "G. E. P. MURRAY." and in the case of these no subscription . been found.In both cases use the least amount of " juice " consistent with good will be payable. signal strength. Our Comment Among the many objects of the associa- Taken inconjunction with the corre-tionarethepromotion,encouragement Self -oscillation spondence which we published last week,and protection of the manufacturers' and Each additional step of high -frequency itis evident that there has been a verytraders' interests; the guidance of public amplification increases the tendency of thesignificant change of front on the part ofopinioninmatters thatvitally concern set to fall into self -oscillation.The signs. the Post Office during recent weeks. Wethe wireless trade; the establishment of a of this can be readily recognised :signalsvery heartily congratulate the Post Officepatent bureau (the very first duty of which become " woolly," andif the aerial ter-officials on having taken such a wide andwill be to investigate the present patent minal is touched with a wet finger a dis-generous view of the situation. position); the compilation and distribution tinct " tap " is heard in the phones.The It follows from last week's correspon-ofstatisticsoftheindustry;and the questionofeliminatingself -oscillation dence that the Post Office recognises thatformationofacourtofarbitration, to will be dealt with fully in a later article;experimental licences arefor those whowhichdifferencesanddisputes can be for the present it will suffice to say that itmake _their own sets, or for persons whoreferred. can usually be prevented in small sets (s)produce evidence that they are qualified to We are informed that the association' by using thesmallest efficientreactionconduct experiments. has already entered into communication coil; (2) by lessening filament current or That.isagreatpoint.Thecorre-with the British Broadcasting Company: anode potential;(3) by working alwaysspondence that we print above establishesand also with the Postmaster -General ori: with the loosest possible coupling. another one. matters of immediate concern to the in- The set that is being described isre- In the present case the applicant had adustry, and from our acquaintance with' markably quiet in its working, but para-Peto Scott set which he had built up fromthe trade generally we are of opinion that' siticnoises may make their unwelcomeparts purchased from the manufacturers.the association will supply " a long -felt appearance. at add times in any set.IfEvidently. the Post Office did not think thatwant."It would be well for all interested they occur, suspect the batteries first, and this was a case_ for an experimental licence;members of the trade to. put themselves if- they prove -blameless look forloosebut, inasmuch as the set had been built .upintocommunication withthesecretary; connections. R. W. HALLOWS. from parts supplied by a British manu-whose name and address we give above. DECEMBER 9,1922 617 &total r Wtrdesi C]1=2111EJCIOCICIClEggEICEECEIggEl be denied entrance.One gratifying resultcompanieshavebeennegotiatingfor Cl has been the greatly increased member-rights, but the Government is unable to CI ship.At the subsequent meeting of themove, owing to the fact that Great Britain CI Radiograms CI club no fewer than sixty-nine new appli-has not yet come to a decision. cations were submitted.

CALACIICICELLIKI It is stated in certain official quarters in The British Broadcasting Co. has de-Glasgowthatunderthebroadcasting THE Right. Hon. F. G. Kellaway, P.C., cidedthatthetemporaryBirminghamscheme the stationfor the Lowlands of hasbeenappointedadirectorof district broadcasting station is to be at theScotland, which was provisionally fixed Marconi's Wireless. Telegraph Company, GeneralElectricWorks,Witton,Bir-for either Edinburgh or Glasgow, will be Limited.This appointment was the sub-mingham. established in the latter city.At one time ject of questions in the House of Commons atown midway betweenthetwobig on November 30. centres was suggested. At the special request of the King, whilst on an unofficial visit to the Marine and CY,..n.."-rwvw.rwC) The Cunard Steamship Company haveSmall Craft Exhibition on November 22nd, 'decided to maintain its own wireless ser-a message was sent through by wireless BROADCAST TELEPHONY Some of these transmissions are commercial vice instead of employing Marconifrom Buckingham Palace to illustrate toor official.Wave -lengths and times are liable operators. His Majesty how H.R.H. the Duke ofto alteration without notice. York opened the exhibition. London B.B.C. Station (2L 0), 369 metres.

Daily, usually 5 p.m. to to p.m.

It is stated that Mr. R. E. 'Williams, of ManchesterB.B.C.Station(2Z Y), 385 Holyhead, employing only three valves, Walsall Education Committee has sanc- metres.Daily, usually 5 p.m. to to p.m. hasreceivedaconcertbroadcast fromtioned a grant of thirty shillings towards Birmingham B.B.0 .Station(2W P),425 the cost of installing wireless apparatus in metres.Daily, usually 5 p.m. to to p.m. America. Croydon (G E D), goo metres. Daily. ix a Council school, provided that itis for Writtle(2M T),400 metres. Tuesdays, the use of the children.The teachers and8 p.m. Apilotlessbiplanewassuccessfullyscholars have agreed to find the remainder Eiffel Tower (FL),2,600 metres. Daily, directedandcontrolledby wirelessatof the apparatus. 6.20 p.m.to 7 p.m. Etampes on November 24. The Hague (P C G G), 1,085 metres.Sun- days, 3 p.m. to5 p.m. Rome (I C D), 3,200 metres.Daily, to a.m. Telephony was received from Newark PresidentHarding'sspeechtothe Kfinigswusterhausen(L P), 2,800metres. SenateontheShipSubsidyBillon (W Z), United States, 3,75o miles from Daily, 4 p.m. to 5.30 p.m. November 21 wasbroadcasttothe Amsterdam (P C A),i,800 metres. Daily, London, on November 27, by Mr. Frankcountry. t.to p.m. Phillips, chief engineer of Messrs. Burn - Haren (0 P V H), goo metres.Daily, every dept, Limited.This is the first time on hour from 11.20 a.m.to 4.20 p.m. record that a wireless concert has been The Detroit Police Department has been receivedinEngland from America.A issued with the call letters K 0 P.Pure special note appears in.another column. genius on somebody's part.

66 WO R K " II U

on The proprietoroftheWilton Arms, Inalectureanddemonstration Thornton Heath, has a wireless receiver in Broadcasting " the lecturer, Mr. CHRISTMAS his saloon -bar, and customers are enter-Anthony Harkey, mentioned that an ether tainedwithconcerts fromthevarious wave could travel seven and a half times NUMBER broadcasting stations. round the world in a second. w GREATLY ENLARGED Capt. J. W. More, Huddersfield's chief The missionaries of the Methodist Epis- USUAL PRICE - 3d. constable, has received permission toin-copal Church have decided to use wireless stallwirelessapparatusatthecentraltelephones as well as aeroplanes as an aid police offices.This is the second ofitsto carrying missionary work into the in-This week's issue is a special number and kind, the first being at Middlesbrough. accessible parts of China. contains over a dozen articles of a seasonable

nature in addition to theregular features A noticeable omission in the programme A suggestionis made that buses and of the London Broadcasting station is thattrams should be equipped with receiving PRINCIPAL CONTENTS of so far little has been transmitted of theapparatus for the entertainment Amateur Wireless at Christmas nature that appeals to children. passengers. Easily -made Chinese Lanterns w A Cliff Tramway : A Working Toy that will IN Scottish amateurs must be amongst the stand hard use Letters from two South African corre-smartest going.The latest report-fromParlour Tricks for Christmas Parties spondentsstatethattheconditionsforthe Ayrshire coast-isthat Birmingham"Making -up" for Amateur Theatricals receiving are very bad.Only telegraphyand The Hague have both been excellentlyOn the Rise of the Curtain :an Illusion in which the Conjurer Introduces Himself can be heard, and atmospherics are veryheard on a rubber -covered4o -ft.aerial bad. AMATEUR WIRELESS has to be only 18 ft. from the ground.The musicMaking Christmas Cards at Home ordered in advance, and costs 6d. A Santa Claus Sleigh was audible at a distance of 6 ft. from theStanding Figure Calendars phones.The set was quite an ordinaryHome Decorations and Illuminations one; with two stages of amplification. The only drawback at the Glasgow and The Master Puzzle District Radio Club's wireless exhibition Some New Conjuring Tricks for the Amateur was that the accommodation in the hall The P.M.G. of New Zealand has statedPreparing for the Christmas Party was quite inadequate. Two thousand per-that he is in favour of New Zealand havingThe Parlour Stage and Its Arrangement sons paid for admission, but owing to the directwireless communication with the congestion at the show many more had toworld instead of the chain system.Two40 pages 3d. Fully Illustrated. 618 619 ematthr Wireies3 aIDAl ill AiLe11=1DMEMIll 01:1001:1 a a 1170g**** 17TJEJEILIDID**1:1*E113:]g*D1=1*Ell=111=1**5._COEl*WarlEREDI=I[DME11=1****ElE1

THE Postal Service, which covers the The Introduction of srP7 widest possible man- vestigations, the Act entitles him to have I collection,transmission and delivery Wireless ner theinstallation a licence, as a matter of right.But itis El of written communications generally, has The inventionof or use of any wire- still left to the Postmaster -General to say always been a State monopoly, and is at wirelesssignalling, lessset,eitherfor what constitutes a satisfactory proof that THE LEGAL POSITION OF El present vested in the Postmaster -General. in turn, opened up a , receptionortrans- the applicant is in fact an experimenter. The introduction of the telegraph as fresh avenue of pos- mission,by anyone Further, the licence may be hedged in with El a new mode of communication was fol- sible encroachment who has not fortified whateverrestrictions the Postmaster - El lowed in 1869 by the passing of the Tele- THE WIRELESS AMATEUR General may think proper. 1=1 himself by a licence upon the pos61 pre- El graph Act which gave thePostmaster - serves.The new de- from the Postmaster - The average amateur probably thinks ',.111!1111:1'.11s.:1:11:11111.:111111:111111111111111HIPIE Generaltheexclusiveprivilege(with velopment was An Authoritative article, specially written at the request General.. Further, thatthisconcession practically amounts certain exceptions in favour of railway accordingly met by thePostmaster - to nothing, as it leaves too much to the l511:11111111111:111/1:111I11111111111111111H111111111 of the Editor of " A.W. "' bya Barrister -at -law. SIIIIIIIIIIIIIL companies, etc.) of transmitting telegrams the passing in1904 General is given discretionof the authorityin power at El andofperformingalltheincidental of the Wireless Tele- entirediscretionas the Post Office.To a certain, extent this services of receiving, collecting and de- El a graphAct, under towhattermshe criticismistrue enough. If,however, livering them. which the present W.T. Broadcastand For good or ill, then, the Act of 1904 ;,It goes on to declare that a licence shall mayimpose as a condition for granting theadministrativeofficialinpractice Experimental Licences are issued. governs the position to -day, and determines be in such form and for such period as the thelicence. abuses his authority to such an extent as

Government Monopoly OriginallythelifeofthisActwas the relation in which the would-be user l'ostmaster-General may determine, and Section 2 sets out that where an appli- toevadethespiritof theAct,itis When in the year 1880 the telephone limited to a period of two years, from the of wireless apparatus finds himself -hallcontain the terms, conditions and cantfor a licence furnishes satisfactory always open to an aggrieved applicant made its appearance as a commercial pro- 15th of August, 1904, to the 31st July, 1906. situated, both as regards the law generally restrictions on and subject to which the proof to the Postmaster -General that his who is a bona -fide experimenter to appeal position,the Postmaster -General claimed Possiblytheauthoritiesthoughtthe and the Postmaster-Gener=k1 in particular. licence is granted.The fees payable for sole object in obtaining the licence is to to the High Court for a mandamus to thatits use was an infringement of his newfangledwirelesscontrivancewould alicence areto be determined by the enable him to conduct experiments in wire- compel the Postmaster -Generalto carry monopoly rightsundertheabove -men- be dead and forgotten by then.Curiously Restrictions Pbstmaster-General with theconsent of less work, a licence for that purpose shall out the provisions of the Act, and to grant tioned Act.This view was upheld by the enough,itsurvived and flourished, and In these circumstances it is most impor- the Treasury. be granted, subject to such special terms, a licence upon reasonable terms. courts,andinconsequenceitbecame it therefore became necessary to pass a tant that every owner of a wireless set conditions and restrictions as the Post- necessary for each telephone company to new Act in 1906, which in one curt para- should have a clear idea of what restric- Ati Explanation master -General may think proper, but shall Licence Fees hold a licence, and to pay a royalty of graphextendedtheprovisionsofthe tions and duties the statute imposes. The expression "Wireless Telegraphy " not be subject to any rent or royalty. The statement that such licences are free ten per cent, on its gross revenue to the former Act until the 31st December, 1909. The first section of the Act lays down is laid down to cover any system of corn- from any payment in respect of rent or Post Office-a state of affairs that lasted Since then the original statute has been that no person shall establish any wireless :"....nication(in the nature of telegraphy) The Rights of the Experimenter royalty requires somelittle explanation. untilthe National Telephone Company extended from time to time up to the pre- telegraph station or install or work any without the aid of any wire connecting the The purport of the above paragraph is ThePostmaster -General'smonopolyin was bought out by the State.Now prac- sent day in a somewhat furtive manner, apparatus for wireless telegraphy in any transmitting andreceivingends. The to exempt a genuine experimenter from wirelesssignallingisanalogoustothe Ei tically all existing public telephone sys- and in company with sundry other minor place except under and in accordance with definition covers wireless telephony. the monopoly powers of the Postmaster - position a patentee occupies in respect of tems have passed into the hands of the legislation, by means of a succession of a licence granted to him by the Postmaster - It will be observed that the effect of the General.Provided that he can prove that aprotectedinvention, and therentor Post Office. Expiring Laws Continuation Acts. General for that purpose. above paragraphsistoprohibitinthe his only object is to carry out wireless in- royaltyhere referredtoisamonetary

"Grarnaphix " Loud -speaking Attachment for Gramophone. Examples of some Loud Speakers Usual Types THE first photograph shows aloud speaker of the self-contained type in conjunction with a5 -valveamplifier.An attachment for the phones that amplifies the sound is shown in the next picture, the usual ear -pieces being simply slipped on to a specially -constructed horn. Use of the same principle is made withthe arrangement shown inthe third photograph, in this case thesound chamber ofthe gramophone being utilised to amplify the sound. The next photograph shows anotherloudspeaker of the self- contained type,whilst the last picture is that of a loudspeakerarranged in cabinet lorm. "Broadcast De Luxe (T. H. Isted). "Aero" Adapter(1. A. Coomes, Ltd.). " Magnavox." "Radio Teleola." 0 0 0 0 0**E*1********IMEI gE***4--JDE] El 618 619 ematthr Wireies3 aIDAl ill AiLe11=1DMEMIll 01:1001:1 a a 1170g**** 17TJEJEILIDID**1:1*E113:]g*D1=1*Ell=111=1**5._COEl*WarlEREDI=I[DME11=1****ElE1

THE Postal Service, which covers the The Introduction of srP7 widest possible man- vestigations, the Act entitles him to have I collection,transmission and delivery Wireless ner theinstallation a licence, as a matter of right.But itis El of written communications generally, has The inventionof or use of any wire- still left to the Postmaster -General to say always been a State monopoly, and is at wirelesssignalling, lessset,eitherfor what constitutes a satisfactory proof that THE LEGAL POSITION OF El present vested in the Postmaster -General. in turn, opened up a , receptionortrans- the applicant is in fact an experimenter. The introduction of the telegraph as fresh avenue of pos- mission,by anyone Further, the licence may be hedged in with El a new mode of communication was fol- sible encroachment who has not fortified whateverrestrictions the Postmaster - El lowed in 1869 by the passing of the Tele- THE WIRELESS AMATEUR General may think proper. 1=1 himself by a licence upon the pos61 pre- El graph Act which gave thePostmaster - serves.The new de- from the Postmaster - The average amateur probably thinks ',.111!1111:1'.11s.:1:11:11111.:111111:111111111111111HIPIE Generaltheexclusiveprivilege(with velopment was An Authoritative article, specially written at the request General.. Further, thatthisconcession practically amounts certain exceptions in favour of railway accordingly met by thePostmaster - to nothing, as it leaves too much to the l511:11111111111:111/1:111I11111111111111111H111111111 of the Editor of " A.W. "' bya Barrister -at -law. SIIIIIIIIIIIIIL companies, etc.) of transmitting telegrams the passing in1904 General is given discretionof the authorityin power at El andofperformingalltheincidental of the Wireless Tele- entirediscretionas the Post Office.To a certain, extent this services of receiving, collecting and de- El a graphAct, under towhattermshe criticismistrue enough. If,however, livering them. which the present W.T. Broadcastand For good or ill, then, the Act of 1904 ;,It goes on to declare that a licence shall mayimpose as a condition for granting theadministrativeofficialinpractice Experimental Licences are issued. governs the position to -day, and determines be in such form and for such period as the thelicence. abuses his authority to such an extent as

Government Monopoly OriginallythelifeofthisActwas the relation in which the would-be user l'ostmaster-General may determine, and Section 2 sets out that where an appli- toevadethespiritof theAct,itis When in the year 1880 the telephone limited to a period of two years, from the of wireless apparatus finds himself -hallcontain the terms, conditions and cantfor a licence furnishes satisfactory always open to an aggrieved applicant made its appearance as a commercial pro- 15th of August, 1904, to the 31st July, 1906. situated, both as regards the law generally restrictions on and subject to which the proof to the Postmaster -General that his who is a bona -fide experimenter to appeal position,the Postmaster -General claimed Possiblytheauthoritiesthoughtthe and the Postmaster-Gener=k1 in particular. licence is granted.The fees payable for sole object in obtaining the licence is to to the High Court for a mandamus to thatits use was an infringement of his newfangledwirelesscontrivancewould alicence areto be determined by the enable him to conduct experiments in wire- compel the Postmaster -Generalto carry monopoly rightsundertheabove -men- be dead and forgotten by then.Curiously Restrictions Pbstmaster-General with theconsent of less work, a licence for that purpose shall out the provisions of the Act, and to grant tioned Act.This view was upheld by the enough,itsurvived and flourished, and In these circumstances it is most impor- the Treasury. be granted, subject to such special terms, a licence upon reasonable terms. courts,andinconsequenceitbecame it therefore became necessary to pass a tant that every owner of a wireless set conditions and restrictions as the Post- necessary for each telephone company to new Act in 1906, which in one curt para- should have a clear idea of what restric- Ati Explanation master -General may think proper, but shall Licence Fees hold a licence, and to pay a royalty of graphextendedtheprovisionsofthe tions and duties the statute imposes. The expression "Wireless Telegraphy " not be subject to any rent or royalty. The statement that such licences are free ten per cent, on its gross revenue to the former Act until the 31st December, 1909. The first section of the Act lays down is laid down to cover any system of corn- from any payment in respect of rent or Post Office-a state of affairs that lasted Since then the original statute has been that no person shall establish any wireless :"....nication(in the nature of telegraphy) The Rights of the Experimenter royalty requires somelittle explanation. untilthe National Telephone Company extended from time to time up to the pre- telegraph station or install or work any without the aid of any wire connecting the The purport of the above paragraph is ThePostmaster -General'smonopolyin was bought out by the State.Now prac- sent day in a somewhat furtive manner, apparatus for wireless telegraphy in any transmitting andreceivingends. The to exempt a genuine experimenter from wirelesssignallingisanalogoustothe Ei tically all existing public telephone sys- and in company with sundry other minor place except under and in accordance with definition covers wireless telephony. the monopoly powers of the Postmaster - position a patentee occupies in respect of tems have passed into the hands of the legislation, by means of a succession of a licence granted to him by the Postmaster - It will be observed that the effect of the General.Provided that he can prove that aprotectedinvention, and therentor Post Office. Expiring Laws Continuation Acts. General for that purpose. above paragraphsistoprohibitinthe his only object is to carry out wireless in- royaltyhere referredtoisamonetary

"Grarnaphix " Loud -speaking Attachment for Gramophone. Examples of some Loud Speakers Usual Types THE first photograph shows aloud speaker of the self-contained type in conjunction with a5 -valveamplifier.An attachment for the phones that amplifies the sound is shown in the next picture, the usual ear -pieces being simply slipped on to a specially -constructed horn. Use of the same principle is made withthe arrangement shown inthe third photograph, in this case thesound chamber ofthe gramophone being utilised to amplify the sound. The next photograph shows anotherloudspeaker of the self- contained type,whilst the last picture is that of a loudspeakerarranged in cabinet lorm. "Broadcast De Luxe (T. H. Isted). "Aero" Adapter(1. A. Coomes, Ltd.). " Magnavox." "Radio Teleola." 0 0 0 0 0**E*1********IMEI gE***4--JDE] El emateur Wireless 620 DECEMBER 9, 1922 payment as consideration for the privi- Since then the phenomenal developmentscuits. Incidentally, why do the makers lege of sharing the monopoly.The feethat have taken place in radio science pro-of valve -holders design them so that such of ten shillings actually charged for anmise to make a wireless receiver mosttroublesarepossible? Ifthebrass experimentallicenceisnotarentorcertainly anasset,ifnot an absolutesockets are well sunk in the ebonite there royalty proper, but merely covers the ad-necessity in every home in the- country. is no risk.One would have expected it ministrative charges connected with the Under such circumstances how can oneto be thefirstthing a designer would examination,grant andregistrationofcontemplate without amusement the casethink of, but so far I have only met one such licences. of some respectable householder, or thecase inwhichthispoint has received It should be pointed out that licencesstill harder case of his youthful but im-attention on a standard design.-C. B. to receive broadcast matter do not fallpecunious son and heir, being solemnly(London, S.W.). under the above -mentioned section of thethreatened by an irate P.M.G. with the Act. They are not to be obtained as ahorrible fate laid down by the Wirelesspwwv matter of right under the statute, nor areTelegraph Act of1904forthose who they necessarilyfreefrom the duty toneglect to procure or renew the necessary pay rent or royalty.In fact, however,licence.In all seriousness, the law should CLUB DOINGS as is well known, such licences are beingcommand respect, not provoke a grin. granted under certainconditionstoall In effect the 19o4 Act with its absurdly who care to apply for them. drastic powers and penalties is completelyIlkley and District Wireless Society Hon. Sec.-E. STANLEY DOBSON, Lorne House, The fee charged, namely ten shillings out of touch with present facts. The soonerRichmond Place, Ilkley. year,happens to be the same asthatit is replaced upon the Statute Book by a A MEETING of the society was held on Nov. 6, levied upon theexperimenter,but themeasure more in accordance with publicwhen Dr. J. B. Whitfielp gave a lecture on Postmaster -General would be within hisapproval the better for all concerned. " The Relation Supposed to Exist between Electricity and Matter."The lecturer com- powers in charging any fee he might con- menced by giving a short account of the various sider reasonable, purely as compensation states in which matter can exist, and the for sharing hismonopoly rights,apart means by which it may be transformed, from from any sum due to the purveyors of the CORRESPONDENCE one state into another. Broadcast Service, music, news, etc.As The divisionofmatter by mechanical means wasexplained,showing how the is now well known, the licence fee is to be Motor Racing and Wireless smallest particle into which matter can be shared between the Broadcasting Company SIR,-We have pleasure in 'informing you divided retains all the chemical properties and and the Postmaster -General,thelatter'sthat our experiments on Brooklands with acomposition of the substance in bulk.The portion being probably justsufficient to theory of the subdivision of the molecule in cover registration and general adminstra-wireless equipped car were entirely success-atoms wasexplained,andthedifference ful,and we succeededintransmittingbetween the propertiesof the constituent tion expenses. speech,whilst thecar was circling theelements and the composite substance after chemical action takes place, was dealt with by Penalties track, to a station situated at the top ofreference to salts such as common table salt, The Act lays down some very severethe members' hill.At high speed a slightwith which everyone isfamiliar.The dis- penalties for any infringement of its pro-muffling of speech was noticeable owing tocovery of radio -active elements and the elec- the vibration of the microphone and sway-tronic emissions in a vacuum tube were then visions. traced out, and the modern electron theory Any person installing or using wirelessing of the aerial wires, but these are tech-and its explanation of these phenomena was apparatus without a licence is guilty of anical details which can soon be overcome. explained. The lecturer then gave an interesting misdemeanour.If charged before a magis-The receiver, operated by Mr. Partridgedemonstration of the action of these electronic (2K F), of Merton, was of the four -valveemissions, by means of a very fine X-ray trate he is liable to a penalty of Do. He outfit. mayalsobebroughtbeforeQuartertype-one H.F., one rectifier, and two note - Sessions or the Assizes on indictment, and,magnifying;thereceivingaerial was Hartlepool and District Wireless if convicted there, may be fined anythingapproximately 6oft.long, supported by Society up to Do°, or be sentenced to a maxi-two trees at a height of about 25 ft.EarthHon. Sec.-MR. A. BROWN, 62, Grange Road, mum term of imprisonment of 12 months,was obtained by pushing a screwdriverWest Hartlepool. down a wet drain.Three pairs of tele-VISITORS are invited to any of this society's with or without hard labour.In either weekly meetings, excepting on the first Friday case he is also liable to have his set con-phones were in use. We hope to continueof each month, which is devoted to the society's fiscated. these experiments at an early date.-ELEc-business.Full particulars may be obtained A saving clause, however, says that no TRICAL DISPOSALS SYNDICATE. on application to the secretary. prosecution shall be launched against any .Filament Fuses Ilford and District Radio Society offender except by order of the Postmaster - Hon.Sec.-A.E. GREGORY, 77, Khedive Road, General, the Admiralty, the Army Council, SIR,-I have noted the article in yourForest Gate, E.7. or the Board of Trade. recent issue dealing with the above, andUNDER the auspices of the above society, Finally, a further sub -section states thatthink the following suggestion from mydemonstrations ofwireless telephony were own experience may prove of interest togiven in aid of church funds at the Seven any magistrate (if he is satisfied that there Kings Baptist Church on Nov. 2nd, 3rd, and isreasonable ground for believing thatyour readers. Ithink more valves are4th.Telephony wassuccessfullyreceived any apparatus for wireless telegraphy hasspoilt by hastily replacing them withoutfrom Marconi House, 2 0 N and 2 J X, and was been installed or worked in any placeswitching off the H.T. battery than fromreproduced on a loud speaker loaned by without a licence having been obtained),any other cause.At least that is my ownMessrs. Radio Instruments, Limited. may grant a search warrant to any policeexperience;othersmayhavedifferent (More "Club Doings " onpage 622) officer or Isther properly accredited official,waysofbeingreckless. A %-amp. authorising him to enter and inspect the"Cozwhy " fitted in a holder against the " All -on" Two -valveReceiving Set.- installation and toseize any apparatusnegative end of the H.T. battery may beOn the first page of our last issue a photo- which appears to him to be used or in-relied on to blOw first in such cases.Ifgraph of a valve -receiving set of the small tended to be used for the purpose of wire-the negative terminal is used to vary gridself-contained cabinet type was shown and lesssignalling. potentials, that is,is a wander -plug, thewasthereinadvertentlydescribedas fuse -holdercanbeconvenientlyfittedbeingaproductionoftheTelephone Out-of-date Regulations close by, and a lead of sufficient lengthManufacturing Co., Ltd.The makers of These regulations were framed at a timeto allow for the variation connected be-this, however, are Messrs. Rogers, Foster when wireless was practically initsin-tween it and the plug.This precaution& Howell, Ltd., Edward Road, Birming- fancy,long before the present type ofalso serves to prevent the battery fromham, and the setis styled the "All -on compact apparatus was even dreamt of. being run down by accidental short cir-Two -valve Receiver." DECEMBER 9,1922 621 mattur Wireless wwwv OUR INFORMATION BUREAU Expert Replies to Readers' Questions.Hundreds of Replies are sent by Post. TO ENSURE A PROMPT REPLY PLEASE OBSERVE THE FOLLOWING RULES Write distinctly, give all necessary details and keep to the point.Ask one Question at a time-never more than two.Send a Stamped and Addressed Envelope. Send the Coupon cut from this page.

5 -Valve Amplifier with Switches. set, or any of the following parts, namely, Q.-Will you please give me a circuit dia-Reception of Americanamplifiers (valve or other), telephone head gram of a 5 -valve amplifier with only one pair of telephones and with switches instead of receivers, loud speakers and valves, used jacks, the switches to allow of any combina- Signals under thislicence must bear the mark tion of valves to be used without disconnecting THE following American signals were"B.B.C."The onlyfirmsallowedto leads or 'phones.-J. H. A. (3940) I received on a Burndept Ultra ri 1,toaffix this mark to their goods are those A.-The circuit shown will be suitable.which was coupled an -extra stage of high -who are members ofthe British Broad- The secondary -tuning coil should be connected casting Company, but as at the time of betweenGand F.When wishing to use allfrequencyamplification, making four Valves, the switches should be aaranged asvalves in all. writingthis company has not yet been follows.Switch at G is put to the grid of the From 1.5 a.m. to 3.31 a.m. G.M.T. onregisteredand,therefore,we presume, first valve.The grid switches of the secondSunday morning, November has not yet any legal existence, itis diffi- and third valves should be put to the left, and J Z NewYorkBroadcastingStation,thecult to see how it can have any members. entire programme was heard and under-In spite of this anomaly many firms are . stood. From 3a.m.to3.15a.m.thealready using the " B.B.C." mark, but strengthofthesignalsgraduallyin- apparentlythereare many others who creased until they .\ core eventually audiblewishtobeabletouseitand do not about 12ft. from the telephones. appear to have authority to do so. The following stations were also heard verystrongly :rC M K,1X U, 2A W L ANNOUNCEMENTS (who was calling 5L V and 9Z Y), 2L M, Amateur Wireless andElectrics." Editedby F ) 1 813 P L (who was calling 4X Y, sent him Bernard E. Jones.Price Threepence.Published on LT -E, a message and signed off),. C U L, G M, Thursdays and bearing the date of Saturday imme- diately following.It will be sent post free to any 73G N, SAT F, SA Q 0 (who was calling partofthe world -3 months,4s. 6d.;6 months, 13s. ud ; 12 months.17s.6d. Postal Orders, Post I 5M S Manchester Wireless Society),his Office Orders, or Cheques should be made payable message reading, "Signals faint.Nearly totheProprietors, Cassell & Co. Ltd. Five -valve Amplifier with Switches. General Correspondence is to be brief and written Q R Z," SX A K (who sent a weather re - on one side of the paper only.All sketches and port), 9L G. drawings to be ou separate sheets. the right-hand telephone switch down and the These signals were all received on the Contributions are always welcome, will be promptly other two up.To cut out the lastr, Fvalve, considered, and if used will be paid for. simply raise the last telephone switch and pushsame set by the chief test room assistant Communications should be addressed, according to down the centre telephone switch.To cutof Messrs. Burndept, Ltd., Mr. J. H. D. theirnature,toTheEditor,The Advertisement ...:Dnageror The Publisher, "Amateur Wireless,", out the two L F valves, raise both the centreRidley, who lives at Norwood, near Croy- La Belle Sauvage. London, E.C.4. and end telephone switches and push downdon, and whose aerial is iSo ft. long and the first telephone switch.To cut out the first37 ft. high. HF valve, put switch G on the centre stud and the second grid switch to the right, keeping the third grid switch to the left.To cut out two' w F valves put the switchGto the left- hand stud, and the third valve grid switch " B B C to the right.-1,. C. A SOMEWHAT curious position seems to have developed with regard to the The largest and most powerful trans-use of the above letters.As everybody mitter, it is claimed, has been built on theknows, Condition 2 of the Broadcast Re-Querist's Coupon Available until roof of the lEolian Hall, New York. ceiver Licence states that "Any receiving Saturday, Dec. 16, 1922

,,...... ,...... _.,...... _...... ,...... _...... ,, INVINCIBLE 1 SPLENDID Christmas PRESENTS (cannot be beaten) ,.. 20 i LE ISHE130 ALLISON & CO. YEARS I IN QUALITY AND PRICE i : i L.F. INTERVALVE TRANSFORMERS Crystal, £31With 4,000 ohms These transformers are of the upright pattern, and are manu- "SETS factured throughout at our own works.Several well-known "Valve, £51DOUBLE Headphones wireless manufacturers are using our transformers in their sets, I and we guarantee you complete satisfaction All Sets will or refund full payment by return post. be markedBBCandPMG

i Type A. 17/6Type B. 161- . post free.t Type A. is fitted with brass connectors for wiring to the external circuit. i Send for particulars and testimonials i, Type B.isnot.Otherwise both types are 'identical. :Terms and sal/Wes sent to. Mannfacturers and Traders on application. i 46, 46a, 50 and 50a, CHURCH RD., ACTON i WOODMASON, St. John's St., COLCHESTER. i 1,..... p.a.-or...or... .1.1.,0.11.. 0.1..4 0..11.411...,0.11.N 0.0.-4 4, Wm.less DECEMBER9 1922 Ontateur 622 roundthefrontofthebuilding and usedasan to describe the various methods of communicating MORE CLUB DOINGS earthor,moreproperlyspeaking,abalancing the amplified impulses to the grid of the succeeding capacity, and with thesecretary'sthree -valvere- valve.Transformer, resistance -capacity and react (See also page 620) ceiving set, supplemented by batteries, amplifiers and ante -capacity couplings were dealt with in a way Manchester Wireless Society. a loud -speaker kindly loaned by Messrs.Mitchell, which enabled even the beginnerstounderstand. the results broadcasted by 2L 0 Practical hints given as to the methods of elimin- Hon.Sec.-V.W. . Ev ANs, ParksideRoad, of Rye Lane, all I'rincess Road, Manchester. were made known to the occupants of the crowded atingself -oscillation and " howling "were particu- SUwDAY, Nov.1q.-Ati a.m.the members com- committee rooms, and it is feared that some of them larly valuable. menced a special series oftests with a 1,000 -watt became known to the crowd outside in the street, On Nov. 14 lecture was given by Mr. E.\V. valvetransmitter,calling2F Pand 1A 'A,two From 6 p.m. to 1.3o next morning, when nL 0 closed Penney on " Valves and Valve -receivingCircuits." American amateur stations.Transmission lasted for, down with a notice that they did not know how Mr. The lecturerdealtfirstwiththeelectrontheory, fifteen minutes, and consisted of test messages re- Bonar Law had fared,the secretary stucktohis more particularly in its application to valve -working. ferring to the work in hand. These were repeated every posttoseethat noneofthe termsofthe non - He then briefly described the typical construbtion of hour until 6 a.m., the intervening 43 minutes of each arrived permit had been infringed. valves and theirclassificationinto hard and soft, hour being devoted to listening for replies from the open and closed grid types. above -mentioned stations.The power was derived Manchester Radio Scientific Society. from D.C. generators in series, with a total output Hon.Sec.-H.D.W HEI EHOUSE,16,Todd Street, Liverpool Wireless Society. of 2,50o volts, and using two 430 -watt Marconi valves, Manchester. Hon. Sec.-C. L. LYONS, 76, Old Hall Street, Liver- a maximum radiation of 1z amps was attained on the A GENERAL. MEETING of the above society was held pool. last transmission. on Nov. 16. Mr.J.W. Hand openeda discus- ON Nov. 16 a very interesting demonstration seas As regards thereception,although twenty-three sion on " The Construction of Wireless Sets, with given by Mr.J.H.Swift, w -ho had brought his American amateur stations were registered, there was Special reference to the threevalve set iu operation exceedingly well made five -valve receiver, consisting no acknowledgment of our transmissions. One special atthemeeting." Mr. Hand spokebrieflyabout of two detector and 2 L.F. valves.A special record was an amateur as far west as California, crystal sets for short -distance" broadcast" recep- transmission was given to the society by 2Z Y, and who was only using about 750 watts and radiatingtion, and followedthis up with an outline ofthe both the speech and the musical items were very about amps. Comparatively speaking, withour working andconstructionofthe home-madeset loudlyandclearlyreceived. TheBirmingham' Ss -amp. radiation our messages ought to have beenwhich was on view.Then followed a demonstration Broadcasting station was also picked up (2Z P) very. received quite easily by the American amateurs. " of telephony reception from27, Y. clearly.Some little trouble was caused by unwanted Cables are being exchanged between the American interference from Seaforth G.P.O. station, and in a Radio Relay League and the society with a view to Hackney and District Radio Society. rather amusing duet between thisstation and the boosting up the enthusiasm which has been aroused Hon. Sec.-E. R. Watacka, 48, DagmUr Road, E.g. Metro -Vickers station the latter easily came out on on both sides of the Atlantic, and the Manchester ON 'Nov.qththe chairman read a , letter he had top. amateurs are working day and night improving their received from the Wireless Society. of London 'with Allinterestedpersonsdesirousofjoiningthe. apparatuswitha viewtoeventuallyestablishing society should apply to the secretary. direct interchange of -messages, to be followed by a regard to the position of amateurs under the new special test of telephony, subject to the approval of -broadcastingregulations, and although some very strong opinions were voiced against the restrictions Amateur Wireless Society. theI'.M.G. to 'be imposed on amateurs, the Wireless Society's Portsmouth and District reply was considered satisfactory,it being felt that Hon. Sec.-R.G.H.Core,34,Bradford Road, Peckham Wireless and Experimental Association. Southsea. the Hackney. Society would be able' to fight harder,./a MEETING ofthe above association was heldoft Hon. Sec.-G. SUTTON, IS, Melford Road, S. E.22 on behalf of the amateurs within the ranks of theNov. 8, when an interesting talk was given by the, As was previously announced, thisassociation had national society than outside. secretary, Mr. R. G. H. Cole.Mr. Cole chose AS determinedtogivetheirvice-president,SirFred. Nov. 16th.-Two home-made sets of three valveshis subject " Valves," and fully explained the actions Hall,K.B.E.,D.S.O.,allthewirelessassistance eachwereonexhibition,loanedfor the occasionof these frail members.Mr. Cole explained the two - theycouldin thegeneralelectiontheymight by two members of the society, and with the aid of electron and three -electron valves, and dealt with be allowed by the authorities to give, and had in- a Brown's loud -speaker the latest news of the day, the action of the grid and plate.Mention was made structed their secretary, who on Oct.28 made the as broadcasted by the LondonBroadcasting of the various kinds of valves and how they recti- .pro -formaapplicationtothePost Officeforthe Station, was heard loudly and clearly by all present. requisite permission.This was not forthcoming, and The society meets every Thursdayi at 7.3° p.m., and fied speech in telephony. the project had regretfully been abandoned.Late visitor, are always welcome inthe afternoonofthepollingday,Nov. 15,a South Shields and District Radio Club. message seasreceived thatthepetition PlymouthWireless andScientificSociety, Hon. Sec.-J. A. SMITH, 66, Salmon Street, South ,was granted, and that formal permission would fol- Hon. Sec.-G.H.Lora,'9,Ryder Road,Stoke, Shields. low.It was too late then to put into train all the Devonport. A NEW aegial has recently been erected, and this ,elaborate scheme which had been mapped out, butAT a meeting of the above society, held on Nov. 7, was tried out on Nov. 7 with a four -valve Burndept an old Army rubber -covered aerial was hoisted up a lecture on "High -frequency Amplification" was set in conjunction with a Brown's microphone relay :the flagstaffatthe committee rooms at17, Grove given by Mr.L.J.Voss. Startingwith anex- and loud -speaker.Among the telephonystations ,Vale, Camberwell, and another length of the same planation of the amplifying region of the"chariteter- heard were the new broadcasting stations at London 'materialstretchedontheothershorterflagpoles istic curve of a normal valve, the lecturgr,proceeded and 'Manchester.

..Nig., BROADCASTING RECEPTION SETS=mmhavi ...., ONE VALVE SET COMPLETE FOR WORKING, £7-10 0 T1 SENDFOR CATALOGUE '''' -, Passed for INCLUDING ALL ACCESSORIES Broadcasting - --,...... : Licence DESCRIPTION -- G.P.O. No. to38. Single valve, mounted on polished 4. -in. ebonitepauel with vari- able condenser, smooth acting resistance, grid leak and condenser and all terminals clearly engraved inwhite, in a mahogany polished cabinet, 9- in, by 5 in, by 5 in. ... g 3 - 15 - 0 MO.! A TAPPED COIL for wave -lengths up to ...... 900 metres with 2 terminals for coils for any - higher wave -lengths...... Thecoilis enclosed and the tappings are brought out to an 8 -way switch mounted in ..-.. the front of the cabinet. -. ACCESSORIES INCLUDED Siemens 54 volt high-tension Battery with plugs -. for altering the voltage 15 - 0 4 volt 5o amp. hour low-tension Accumulator in case with carrying strap ...... 1 - 4 - 0 OINEMON One pair of Sensitive Head Phones of 4,000 MOM= ohms resistance .., ...... 1 - 1 - 0 =MOM One Detecting Valve ...... 15 - 0 -...... Satisfaction guaranteed TOTAL £7-10-0 .... or money refunded. ....-...... - WIRELESSINSTALLATIONS LIMITED, ...... 15. ALDERSGATE STREET, LONDON, E.C...... TTI 11111111111111111111rnilliniliffillillinINHIHMIIIIHMIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIlle:: nrrcluRFO nInv) mateur Wu6s It Speaks for itself and in no uncertain voice THE WORLD'S. STANDARD LOUD SPEAKER

AMPLION WIRELESS At Prices LOUD SOUNDING ranging from RECEIVERS E2 : 10 : 0 are supplied in a series of £15(15: 0 Ten Models Suitable for DAILY DEMONSTRATIONS every service: at the GRAHAM The Home, SHOWROOMS The Laboratory ALGRAPHONE SALON and the 25-26 Savile Row, Concert Hall Regent Street, W.1 MUSIC MASTER" HORN Type AR 13, 120 ohms £6: 0:0

... Type AR 15, 2,000 ohms £6: 2: 6

"Graham" Wireless Pro- Patentees and Manufacturers : SCOTLAND : ductions include "High Mr. F. M. Milligan, Efficiency"Telephone 25 Renfrew Street, Headsetsofimproved ALFRED GRAHAM design and construction. GLASGOW. The "Graham" isthe AND COMPANY best Head Gear money St. Andrew's Works, Crofton Park IRELAND : can buy. Mr. Alex. R. Munday, LONDON - - - S.E.4 41, ChichesterSt., Full !articular: forwarded upon 11111111=111111MINIMMIIIII request,Ask for Folder A. BELFAST. 624 DECEMBER 9,1922 ewntinit-Wireless GREAT REDUCTION IN PRICESP.gsT1Rsat 4000 ohms total BEAVER Splendid Crystal Resistance. Complete Set of Double Headband. Detector CONDENSER Guaranteed highly efficient. Mounted on Ebonite. Complete with Cords.Ball andsocketjoints ;highly PARTS polished nickel cases ;best Tungsten steel magnets. contains: Ebonite Top and Bottom Plates, Machined BEAVER Complete CRYSTAL SETS Aluminium Moving Plates Aluminium Fixed Plates Beaver "MIDGET" Crystal Set. 1 Square Centre Spindle The Ideal Xmas Present.Length 6Fiin.x 4 in.Absolutely 3 Stay Rods, screwed both ends guaranteed.18/- ;complete with 4000 ohm ear -piece, 36/-. Large Spacing Collars 219 No. 2 unassembled 25/ - Small Spacing Collars NO. 1 unassembled 20/- Bronze Coil Spring High -c ass Filament Resistances 4/- No. 3 assembled 27/6 ready for use Ebonite Knob, drilled and 100 ft. Aerial Wire 7/22 S randed Complete with Splendid Tested and Guaranteed 4000 ohm screwfitted H.D. Copperthe best ,.. 3/ 10 Phones, 50/ - Brass Nuts forCentre Spindle Best Quality Switcharms 116 NO: 4 unassembled 35/ - Small Nuts Ebonite Valve Holders Complete with Splendid Tested and Guaranteed 4000 ohm '0005 MF. 8/6 Best Quality 1 /6 Phones, 57/6 .00075 MF. 9/ Best Insulating Composition ... 10d. De Luxe Set No. 5 assembled 66/- ready for use 001 MF.. . .. 11/6 '0002 Condensers 1/6 Complete with Splendid Tested Guaranteed 4000 Phones, 84/ - 0015MF. 13/- *003 ... 2/9 (Passed by Postmaster -Gen ral, G13.0. Regd. No. 198) BEAVER ELECTRICAL SUPPLYCO- Telephone: GERRARD 1900. 109, REGENT STREET, LONDON, W.1. Special Terms to Trade.All Cheques and Postal Grders to be crossed London Joint City and MidlandRank. Indoor Aerialswillgive WILTON splendid results

If you cannot erect an Aerial out of doors, don't worry.Fasten duplicate Wires (strandedcopperor insulated B.B.C. RECEIVERS Pertinax) across the room, three inches below theceiling, insulate them from the walls, and c ,rinectto your Set. Approved by Postmaster -General. You will get results which will surprise you, If you have an upstairs landing CompleteOutfitNo.1.-Comprising Cabinet,Crystal orpassage,four wiresstretched 12 Receiver, with tapped inductance and enclosed detector, inches apart, and connected in pairs- each oboist 30 feet long-will give you fitted special Hertzite Crystal, one Pair " Supreme " Head- practically a P.M.G. Aerial. phones, 4,000 ohms., too feetAerial Wire, Insulators, Use a Peto Scott No. 4 Unit, and you in strong box.An Ideal Christmas Present. No. 4 will receive excellent speech and music Post free£3 10 0 Detector Panelwithout atmospheric disturbances. "Amplions," £2 5 0 (without Valve) Loud Speakers-"Clarivox," £3 0 0. The usualearthleadtowater -pipe 19s. 6d. is required. Splendid Line of 4,000 ohms Headphones ... Detectors-On Ebonite, Special Crystal 2s. 9d. Adding aNo.3H.F. Unitwillenable you All Peto Scott to pick up long-distance Broadcasting stations C.A.V. Accumulators, 4 v. 4o amp. ,.. 18s. 6d. Apparatusis with ease. 26s. manufactured undericense All Peto Scott Units are Brown's 4 000 ohms Headphones 30s. from Marconi "IIsold in sets of parts for 3 Coil Holders-With Extension Handles ...10s. 6d. Co. Catalogue home construction. Detailed free. instructions renderRadio Basket Coils -200-3,00o Metres, for Telephony knowledge unnecessary. Ournew Set of 7 4s. 6d. Booklet 2 Valve Receiving Outfits comprising Receiver - Offices and Showrooms : - explains Valves, Loud Speaker, Aerial Equipment, with Featherstone House, the whole instructions.Made specially for Broadcasting£20 0 0 system Intervalve Transformers ... 15s. 64, HIGH HOLBORN, B.B.C. Crystal Sets...... 35s. w.c.i. g "ST6REE Everything for Wireless - Despatch by Return naciaira0,8 Trade Supplied. WILTON WIRELESS CO., LTD., 120-124,HIGH ST., TOOTING, S.W.17. Phone-STREATHAM533. DECEMBER 91922 625 motour Vireles3

4r:The Universal Electric Supply t iDec. 9 to 24 I'Dec. 9 to- 241 4 BROWN STREET ONLY -- ONLY ,2i1ephonet ONE DOOR FROM MAR KFT Si &stalks/wet L- - 3409 CITY 1892 SALE MANCHESTER G.P.O. Box No. 619. Great Clearance Xmas Sale all Radio Requisites Promptly Supplied. Complete Vary and Crystal Sets for Broadcasting Reception, P.O. Licensed. of Wireless Instruments and Accessories Fully Mu, trated Catalogue, post free, 6d. .. AT .. COIL HOLDER nt finish. Three Coil Type, price 18, - Mounted on polished base. Price 21/.

A perusal of a few of the items belowLL'S will shew that unapproachable value and prices are listed.Purchasers are advised to secure while stocks exist, as a rush will undoubtedly be experienced and replacements at the figures shewn

HONEYCOMB COILS will not be possible.Another opportunity like this will never be presented. LAMINATED Excellent Re-ults. SWITCHARM Wave Lengths. Radius 35 in. rEto4/6 800 5/2 Complete as 300 4/6 i,oss 6/6 OUR COORS ARE GUARANTEED! illustrated. 450 5/- I,50071. BRITISH HEADPHONES 600 6. r,,,sso 7/40 Price2/. 4000 ohms.Very Light. BeautifullyFinished. Stalloy Diaphragms.Complete with Cords.Adjustable Earpieces. " Dispatch, (Soldelsewhere almost exclusively at 3514 by return.".) 19/61113::.ge OUR LATEST BATCH Only 530 left...... Every type of instrument and accessory from Mercury Condensers to Double Slider Tuners at ridiculously low prices can be seen I)111.1N..'oo,, at our showroom. Space naturally precludes c mpletelist FILAMENT 20171, Norember, 1022. RHEOSTAT Messrs. Hall's. Ready DEAR SIRS, mounting.Best'ai' Price 51:6 ..." I am greatly satisfied VARIABLE CONDENSERS: and pleased with the articles Capacity Complete Assembled for already sent." W. H. S. Parts Panel Mounting .001 ... 6/9 ...... 11. 9 .0075 ...... 11/. Strong Wood/ HEATS, .0005 4/3 ...... 919 CONTAINER 90176 November, 1222. .0003 ...... 3/3 ...... to hold up to 35 Sac Leclanche Hall's. ... 5 9 Cells.Price 1/6 DEAR SIPS, ..." All the goods are to Top and Bottom Circular Drilled Ebonite Plates, 1/3 extra TERMINALS. my entire satisfaction," etc. Vernier, 3/- A. BEADLE. M ake rip your own H.T. Intervalve Transformers, Ratio 5 to 1, finest manufacture 1 i9 Batteries. Crystal Sets from 15/- to £3 Easily attached to CHESHIRE, " Royal Phone" Loud Speakers, 4000 ohms resistance, Pocket Lamp Batter_ NO56/1011 19111l'22. les.1/6doz. ebonite horn giving clarity of ton.e..andf tricillikt Hall's. distortion.St ck of 72 only FIXED CONDENSER 28/9 DEAR SIRS, Aluminium CondenserVanes,fixedand moving,reedof NEW MODEL CRYSTALI. All capacities from .00r to 000, . . Goods received safely 22 24 gauge ... Complete with clips. Price 3 - each Id DETECTOR and am very pleased with same." Spacers, true to .001 ... small, doz.Intl;large, doz. 2d B. 13. Ebonite Knobs, tapped 2 B.A. with brass nut- 1st quality,4d;2nd quality 2d MANCHESTER, Aerial Wire, 7;22 hard drawn copper, in 100 ft. lengti s 2 6 14/11/"12. Valve Legs, with nuts and washers ... 1deach ; doz. 9d Hall's. Two Coil Holders, solid ebonite mounted on mahogany... 4/6 DEAR SIRS, Three ,, with long arms to avoid . .. " We thankyou for effects 8.9capacity prompt delivery," etc. A. V. W. Crystal Detectors, adjustable in every way, fluted brass 2 6 PAISLEY, Slider Rods, 12 -in. or 13 -in..in. square brass, drilled both ends, 4d Scotland. El graved Ivorine Scales, 0-180', round or square ends... 31d Hall's. Filament Resistances, extraordinary value, velvet action 2/4 DEAF. SIRS, Switch Arms, .complete with knob, collar, washers, hush Without Crystal,3/6 "Safely- received nuts, etc. lst quality, 1 3 ; 2nd quality 9d Specially Selected Crystal', per Tin. parcel.Delighted with quality Valve Holders, turned ebonite, complete with nuts, 1 /-; 2nd ijual., 8d Bornite, 1/. Copper Pyrites, 1'. Galena, Manganese, 1 - of contents," etc. R. B. E. Crystal Cups ..plainId.;one, two, or three screw 2d Carborundum, Fused Silicon, 1/8 Ir-ra Pyrites, 2.- Large Terminals, complete with nut and washer...each 1d Nickel Filling', :1/6 Contact Studs, iin. x rill., or 7tan.x complete The"Dlyronite" Crystalgives surprisir,g results, 1/9 All originals are at our office, and Wood Alloy,1/6 per Os. with nut and washer... doz. 4d per piece. can be seen on request. Insulators, 2 -in. reels - 1deach ; white ege, 3d ; green egg,4d ;green shell, each 3d ...... Brass Nuts, 2, 3, 4, 5, 6 RA., 21.ri. Washers, 41d 00NDENSER Ebonite Sheets. I, PARTS Fixed Condensers, any capacity ...each 1,3 Fixed and Grid Leak and Condensers combined ... each 2/9 Movable Slider Plunger eolii plete ...each 4d Vanes. Hertzite, 1 6. Bornite Carborundum, Galena, etc. each 31 ia. >c .010 in. 4d Price 1/6 do,. Screwed Brass Lengths, 12 -in. 2 or 4 B.A...... each 3d "Dispatch by return" Inductances, wound 22/24 enamelled wire ... each Centre Rod, 41 in. overall. is no idle boast. Fitted with Orders urder 30/- kindly remit =male postage Indicating Our Stock of Wireless Finger and Balance refunded if excess sent. Send 1 or FREE Catalogue extra large Equipment and Accessories handle. is such that we can supply TRADE BDYI SRPEATTUCRHN Price4/6 every Wireless need at once SUPPLIED Screwed Rod, 7011. per ft. and at lowest prices. If you Ivorine do not see what you want 'PHONE;1282 Condenser in our list, please write us. Scales, Accurately 71, Beak Street, Regent Street, London,W.1 Marked. 1/. each. Between Piccadilly Circus and Oxford Circus 'Buses 3, 6, 12, 13, 15, 32, 51, 53, 59 and 88 pass mateur Wes 626 Utl,t24i5tK9,lyre Ki Ki *iv* rii,**Thc**FL3,7**Ku*Iii,s,uilif*s*iiT*1,,Wis,*iiiii-la iisifir,s,imA51111_,Ifiilaulic411g' gli_71.11*Ai ILLII EX Wail ITLKI illii:K=111 I.j. El * El *El ULO EVERYBODY! WEI El

1 EMINNIMININIINIMIN 11] ElDo YOU Know US ? If not, why not ? it El tci Ef1,_ o COMPARE PRICES! COMPARE QUALITY ! ! u, M A v, . 44 m Eti,. rmi CompleteSetsof PARTSfor MakingVariableCondensers CI M Fil ApprOX. Everything ready to assemble and consist of the following :Accurate Eiji JIiiii Capacityplates inAluminiumPrice Fixed and Moving Vanes, Large and Small Spacer Washers, -iii El Microfarads Centre Square Spindle (Screwed Ends 2 BA), 3 Side Rods, 12 Nuts * II and12 Brass Washers(2BA), Pointer-scale0=180, Terminals, 3 Bushes,X CI '0015 85 10/- Spring Coil Washers, Best Quality Knob with 2 BA Nut in Centre. '001 57 7/6 ALL HIGHEST QUALITY GOODS * * '00075 43 6/6 CI, * '0005 29 5/6 EBONITE TOP and BOTTOM PLATES SUPPLIED (Drilled) Free of a CC * Charge with IN 1-i '0003 19 3/- .0002 13 2/3 SETS :'0015,'001,'00075,'0005 ftli '0001 7 2/- (If wanted for any other 'set include another 11-) * Ell Vernier 3 1)9 Postage, Packing; etc., 11- per set extra, Facking and Postage for 2 sets, 113 X iN 1ft-a LCKi AI 1* M * .L....-__ UNSOLICITEDTESTIMONIALS_.-...... [A MA. J. POOK, Esq., SYDNEY J. ASHWORTH, Esq., W. J. CORLESS, Esq., A [i_11. 101,Day's Road, 9, Paradise Place, 5, Whatman Road, Al ForestHill,S.E.23. 2/10/22. El Barton Hill, Stoke, *1 [3 Bristol.. , Devonport. Ireceived the set of condenser parts quite- co IN. , 17/11/22 13th November, 1922. safely and thank you for the careful packing. 41 0C111 Enclosed 6s.6d.for.0005 condenser parts. The quality, price, and the dispatch of your As regards the parts themselves, they fitted LIA LITwo I had previously(.001 and.0005)have high-class goods leave nothing tobe desired. together splendidly, making a neat instrument, [ drawn admiration from all my friends. Remark- I antstill able to profit by ;lending to you for andIconsider them the best condenser vabie IIIable value, they say. them, especially when qualify is considered. CI on the market. IC . WO Kli

Li ALL the following GOODS POSTFREE at :the SPECIAL PRICES attached for POST ORDERS ° *ii, * .7f you are not satisfied-wit -6 vdiue, return goods and we willrefund all charges A [II Filament Resistances.Most wonderful value in Coed CondenserKnobs,tapped 2 B.A.,at 1)mm. insulating Sleeving,6 yds. for 2/2.By [-A the wireless trade.Each2/6and 3/6.By 2jdoz.By post,' 2/6. M post, 2.16.12 yds. for 4/..By post, 4/6. El Post, 3/- and41- Knobs,with brass nut (2 B.A.) in centre, high- Slider and Plunger, 5d.By post,8d. EN IN Switch Arms,with polished knob, ,bushed 2 BA class quality, 4/,d. each.By post, 7d.6 fur Slider Knob,plunger and 13 in.rod.The lot, Lc [!C nut, laminated blade,springcoil- washer, 2/-.By post,2/6. 8d. Cannot be sent by post. ri nuts and bush,100.and1/6each.By post, crystalDetector,cupsenclosedwithglass war OfficePattern Terminals,complete with M 1/3 and 2/1 each. 1/8doz. Lai cover, dust proof, 4/6.By post,5/3. nut and washer, By post, 2/2 doz. riii CrystalIous Detectors tb.oniry.Simply2/8.marvel- AerialWire,7/22 bare copper, stranded,first SplendidNvnuLtinaejn I) iee egoToedrmsiizneals1,1. completep l substitute. washer,5- class quality, not .a Price per post,1/6. P-,-, Fixed Conden'sers,withterminalspost,on ebonite, 100ft.,2/10. By post,3/10. Priceper .m .003, .0005,.001,.002,.003,1161bypost, 150 ft.,4/3. By post,5/3. Intervalve Transformers.Each,14/,By post, g 1/9; .004,1/21 bypost,2s. Reel Insulators, 1d. 15/.. (Low. frequency.) UAluminium each, 11d. doz.Cannot be Vanes,2 doz.1/..By post. 1/6. RI] Oojah Basket Coils,7 in set, 5/- set.By post, sent by post. TripleCoil Holders,handsomedesignon El t 5/6. Hertzite Crystal,per piece1/3and 1,6.By Ebonite. 18/-.By post, 11/ LI Lead-in Tubes,ebonite, brass ends, 9in.,1/2. post,1/6and119. Large Spacer Washers,3 doz. 9d.By post, 1/-. rill EI By post, 1/6.12 in., 1/4.By post,1/8. Pericon Crystal Detectors, 4/..By post,4/9. Small Spacer Washers,6 doz.1/-.Bypost, 1/4. LI n NEW TRADE LIST NOW READY. WE LICK CREATIONON PRICES AND QUALITY. El * El El CI Ill Fil cii To Callers: We Sell All Component Parts CHEAP! A pi Brass Rods, Nuts, Washers, Screws, Valve Sockets, Valve Pins, Stop Pins at wholesale prices. [Pi * IA El El

We don't sell cheap and nasty telephones. Try our Best French make.Guaranteed quality 'r--- Do 4,000 ohms, 21!-, 25/- (Double).Single, 2,000 ohms, complete [ail HEADPHONES8,000 ohms, 25/- (Double). with cord, 9/-, aPanrpinott1/-. r: *1 * . Li] NOTE ! My terms are strictly cash with order.All orderc by post are despatched at the earliest possible A moment, as we have great pressure just now on the postal department. E+.3 : I-. 27, LISLE S ki -11J M.M RAYMOND, W.C.2.TREET, K. Li w RIGHT OPPOSITE Gerard I To avoid mistakes, this address is close to -1] DALY'S GALLERY DOOR. 4637 Charing X Road and Leicester Square Tube. Lfi_ 11-* gEgEggErIggElgiggClOggggglECIElgEll:EigggigifilgKt' °TraltiO011],r,SI-ADE1gMEJEJEIKIElE1 DECEMBER 9,1922 627 A BALD STATEMENT--ematwr Wtteks3 66 The NEW

Earth -Screened VARIABLE CONDENSER Range from '0001to'001mfd. Costs only14/9Post Free.

Measures 3 in.x 31 in. xI in. only. Is Now Available from Stock. Is made and guaranteed for 12 months by THE RADIO COMMUNICATION CO., LTD. Direct from 34, NORFOLK STREET, LONDON, W.C.2. Or at NEWCASTLE: 17,Sandhill, LIVERPOOL: 67, Dale St. CARDIFF: AtlasChambers, James St. Branches : SOUTHAMPTON: 19, Queen's Terrace. GLASGOW :so, Blythswood Square. THAT MAKES YOU THINK Crystal Receiver 2.Valve Receiver Range 25 tc 30 miles This Model is a cheap and efficient 1 Detector. 1 Low Frequency Amplifier THE receiver Range, 60 to 80 miles SPECIFICATION.-Toning Coil wound TuningCoil wound on an insulated on an insulated former with 24 S.W.G. former with 24 S.W.G. Enamelled Wire Ni ECCA NO enamelled H.C. Wire, having a wave length with 5 tappings to studs.Wave length range of 180 to 1,000 metres,Tappings range, 130 to 900.Variable Condensers. RADIO taken off to 10 studs.Variable Condenser. '0015Mfd.Slain Tuning Condenser. C003 Mfd., tuning in series..001 Mfd. Single Moving Plate Vernier Condenser. Blocking Condenser across telephone ter- 0003 Mbil.Grid Condenser,2 V. Grid Crystal Receiving Set minals. The wholeismounted on an Leak. *001Mfd.Fixed Condenser Ebonite Panel, 71 in. x 51- in. xin., en- across Primary of Low Frequency Trans- for Broadcasting and Morse Reception graved and mounted in Polished Mahogany former.'001. Mfd. Fixed Condenser Case, 5 in. deep.Complete with Sterling across Telephones. Low Frequency Trans- he Meccano Crystal Receiving Set will receive Telephony 'Phones, Aerial Wire, Insulators,Lead-in former,Ratio 51 to 1, Mounted on 5 in. x 12 (i.e. music and speech) from distances of 20 to 30 miles. Tube. CASH PRICEAce 10 plus in, I o.i Ebonite Panel, engraved and in It is a piece of scientific apparatus with which anyone may Royalties,718 Mahogany Case 41 in. deep. With Sterling Telephones,Aerial and Insulators, etc. spend hours of delight and enjoyment, "listening in" to Note Magnification Panel broadcasting stations and other telephony transmissions. SPECIFICATION.-Low Frequency £10 10plus Royalties. Transformer, Ratio 51 to 1, wound with It has been thoroughly tested and has received with great S.S.C. Copper Wire.Filament Resistance 3 -Valve Receiver clearness broadcast music and speech in London, Paris, of 5 ohms.Mounted on an Ebonite Panel, Detector.2 Low Frequency Amplifiers New York and elsewhere. 7 in. x 6 in, x ain. in Polished Mahogany Case. PRICE CASIIpis As above but with extra stage of amplifi- The Meccano Receiving Set is low in cost and is Royalties. cation on Panel 14 in. x 12 in. x I in., en- These can be supplied up to 3 stages of graved and in Mahogany Case 41 in. deep. complete in itself, ready to be connected to any aerial. Note Magnification from a Broadcasting A complete Aerial Set is sold separately. Station. 3 -ValveReceiver The Meccano Radio Receiving Set 4 -Valve ReceiVer 1 High Frequency. i Detector.1 Low makes an ideal present for Christmas. 1 Detector,3 Low Frequency Amplifiers Frequency Give one to your boy and make him SPECIFICATION.-As preceding models, SPECIFICATION.-'0CO2 Variable Con- happy. but with 3 stages.of Note Magnification for denser Tuning Primary of ILF,Transformer. Loud Speaker reception. Mounted on Tuning Coil wound on insulated former Send forthis Book Panel, 16 in. x 14 in, x l in,,in sloping with 24 S.W.G. Enamelled Wire.Wave- Our new booklet, The Mahogany Desk -shaped Cabinet, All Valves length range 130 to 1,200 metres tapped off Meccano Crystal Receiving Set, are sunk in panel, visible from front. to 10 studs.Mounted on Ebonite Panel 12 in. x 14 in. x / in., engraved and in explains Radio so that every- 4 -Valve, 1 H.F., 1 D., 21.F. Mahogany Case 41 in. deep.This model is one is able to understand recommended for use when the situation is how simple is the reception As above, but with one stage of Radio of broadcasting, telephony Frequency Amplification, and two stages of 30 miles or farther from a Broadcasting Start Radio Note Magnification. '0002Mfd,Variable Station. and Morse messages. This Now in an Efficient Condenser tuning Primary Winding of IL F, booklet will be mailed free and Inexpensive Way Transformer. This model is strongly recom- MANUFACTURERS OF COMPLETE on request. mended for reception over long distances. PELICMS. All the above Modelsare Approved WIRELESS INSTALLATIONS Meccano Crystal Receiving Set,complete, price as/.

ELECTRICAL ENGINEERS, Aerial Set(including antenna, lead H. A. WHITE & SON, in and aerial wires and insulators) 12/6 229, Pentonville Road,KING'S CROSS, LONDON, N.1. MECCANO Ltd Binns Road LIVERPOOL Telephones. CENTRAL 3045,HAMPSTEAD 7872.HAMPSTEAD 648. entateur Wtrdzss 628 DECEMBER 9. 1922

111111111111111111,1 11111111 11

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70, the ,011, i;Mu aitattelea Xmas 1922 is the first time you will be able to give a really novel present : A Wireless Set A presentin which thefascinationand enjoyment never fails. We offeracompleterangeofwireless receivers from simple crystal sets to cabinets de luxe. All T.M.C.. wirelessreceiversarefully approved by the P.M.G. and give maximum results from the British broadcasting. The illustration shows the T.M.C. Crystal Set No. 2, with Patent Everset Crystal which needs no adjusting. £5-17-6 each Come and choose your present to -day. If you cannot call,full particulars will be sent on request. The Telephone Manufacturing Co., Ltd. 68, Newman Street, W.1 Telephone Museum 5581 TMCBRANCHES IN EVERY LARGE TOWN makes Wireless wort -h while.

11

37 DECEMBER 9,1922 629 0190.tatt" Wisviess BROADCASTING GENTS' "DISCOL" HAS NOW BEGUN! H.F. TRANSFORMER HAS BECOME A

- STANDARD FITTING your Set yet ? IN THE Have you obtained RADIO WORLD AND IS IN LARGE DEMAND OUR No. CRYSTAL DETECTOR SET is suit- BY EVERY CLASS OF USER. able for reception of all broadcast matter for a ASK YOUR DEALER FOR range of 20-30 miles.Type approved by P.M.G, GENTS' "DiSCOL " TRANSFORMER - 6/8 EACH. Reg. No. 126.Price 35s. plus 7s. 6d. Broad- GENT & Co:, LTD:, FARADAY WKS., LEICESTER castingroyalty. British made, London: ns, Victoria With Phones. Newcastle.on-Tyne. " Tangent House," Blackett St. wound to 4,000 ohms.Price 60s. and Broad- castingroyalty. Aerialequipmentcomprising BEGINNER'S GUIDE TO WIRELESS tooft.7/22 Stranded Aerial wire and 2Insu- Explains inplain, everyday language, everything lators, 4s. extra. beginners wish to know about Wireless Telegraphy. HOW TO ERECT, CONNECT, AND MAKE Everything complete £3 3 0 plus Broad- all the apparatus required for reception of telephony or morse, and full instructions and diagrams for making coils, tuners, and casting royalty, 7/6.All accessories and compo- complete valve and crystal sets.112 pages, price post free. nent parts. SAXON RADIO CO. (Dt2.), South Shore, BLACKPOOL 32 page Catalogue of Wireless Apparatus, 3d. post free. Write for illustrated Catalogue HEADPHONES, 4,000 ohm, English make, guaranteed .. 15 0 FELLOPHONE 2 -VALVE RECEIVER, in Oak Cabinet, with Headphones,Batteries,Accumulator, Aerialand Insulators £90 0 2 -VALVE AMPLIFIER, in Oak Cabinet(for loud speaker) £50 0 SUPER CRYSTAL SET, with double Headphones, Aerial BOWER ELECTRICLTD., and Insulators £40 0 15, GRAPE STREET; : Superior Resistances, 5/.; L.F. Transformers, 211.; Knobs, 5d. : Condenser Dials, 1/9; Milliard " Ora " Valves, 151-; Mullard Grid SHAFTESBURY AVENUE, London,W.C.2 Leaks, 5/- ; Ebonite Block Condensers, 0003, 2j9 ; Switch Antis, 3/6. F. N. GOUVY & CO., Ltd., 31, Upper Brook Mews, Lancaster Gate, near Paddington Station. How did YOU receive the ELECTION RESULTS ? BATTERIES IT can be confidently said that all who were listeningin with a WatesSetwere very BROADCAST pleased with the reception when the Election RECEIVING SET results were broadcasted. Price complete with British The reception was good-not only because Wates made headphones, aerial and Sets are perfect in manufacture, but also because everything ready for fixing- purchaser, canavailthemselves ofthefree advice of our technicalexperts, who can help £5 0 0 them togetthebestpossibleresultsunder Batteries Plus 7/6 Broadcasting Fee. varying circumstances. Low FrequencyAmplifiers Not only do we manufacture complete receiving sets for for use in conjunction with of the best quality, but also all component parts. this set having special trans- formers-Price The illustration is that of the PYRAMID H.T. Battery, which we can confidently recommend to £5 0 0 help you to get better results.Itis priced as Two of these amplifiers are follows :- Valve Sets capable of working a loud speaker with excellent results 15 -Volt - - within a distance of zo miles 3/6 24v. 28v. 32v. front London. With variable plug connection Type B.K. Filament Resistances .3;9 30 -Volt- - 7/6 " Ideal "Valve Accu- mulator in case Send 3d. stampsforour IllustratedCatalogue. Owing to the demand for these batteries, 4 -Volt 5o amp. 251 - all orders will be dealt with in strict rotation. (Carriage 2/.) List of H. T.Batteries or Accumulatorsfree. 6 so amp. . 35/. Prices approximately oneshilling a volt. (Carriage 3/ -) Variable Condensers (of :: Ask for Leaflet 4030 :: various capacities) From 6/ - Fixed Condensers. 2/6 3 -Coil Holder, complete Unitforusewith 00:11j1nrA ib ELECTRICAL STORAGE .. 20/. Standard Coils. A' COMPANY LIMITED. Callatour Showrooms-they will interest you CLIFTON JUNCTION, I 219/229, SHAFTESBURY 13/14, Great Queen Street, Nr MANCHESTER. AVENUE, W.C.2. Wales Bros.KINGSWAY, LONDON, W.C.2. PRICES AND PARTICULARS ON APPLICATION. etwateur Wireless 630 DECEMBriP. 9,1922 CRYSTAL Notice to Advertisers BROADCASTING PORTLAND'S PARTS BY POSTADVERTISEMENT INSTRUCTIONS and RECEIVER copy for" AmateurWireless "should be at the PASSED BY G.P.O. office by First Post on FRIDAY morn- Totally enclosed in highly polished "EBONITE " Cabinet with accommodation for £s. d. £ c. d. ing at the latest. Phones. Mounted on Ebonite 4 x 4 1 3 12 x 7 .. 2 plate. 7 X 5i 28 .2 X 8i ... 5

8 X 6 30 12 X 10 6 Price - £2 10 0 9 X 6 3 5 is X 811. PREPAID ADVERTISEMENTS. With 4,000 ohms phones, too ft. 10 X 6 39 12 X 12 ... 0 aerial, insulators and lead-in tube. 12 X 4 2 x71 X fifi . 6 Carriage paid U.K. £4 0 0. 9x 8i 4 10 14 X I2 ... 105 Working drawings sup. 17 x 5 53 x8 X 18 (Hall sheet) 1210 Make Your Own Sets. Valve Broadcast Receiving Set. ...130 plied.Write to-clay-Puckle, Buckhurst Hill, Essex. Passed by R M.G. Tax paid. lb. 30 36X 18 ... [23 £9 0 0. 28 11., £4 Accumulators,plates,parts,accessories.Expert 3 Valve Cabinet. Receiving Set. repairs.-Barnard, 43, Great Ormond Street, W.0 .r. Passed by P.M.G.Tax paid, No charge for cutting, waste or postage [12 £15 0 0 Delivery by return of post WirelessDealersthroughoutGreatBritainare 4CCESSORIES & SMALL PARTS SUPPLIED. LIST FREE. stronglyadvisedtostockpartsformaking up Quality Al. DRILLING, Manufaclure, BRITISHwireless sets. Buy your parts direct from the factory Our Motto:" EFFICIENCY with CHEAPNESS." at wholesale prices.-Nevvtonia Wireless Factory, 13 Thickness, one Quarter-Surface, Mat and 15, Whitcomb Street, London, W.C.2. C. S. MILLS, Huge Purchase of ex -Government Wireless Stock. 135, High Street, Notting Hill Gate, LONDON. Write for list giving full details.150 -watt dynamos, JAMES PORTLAND, £1 ;hedgehogcoils,3s.6d. ;loudspeakers,zoo 39, SINCLAIR ROAD, OLYMPIA, W.14ohms, 7s.6d. ;1 -in.spark coils,ios. ; spark coils, 12s. 6d. ; morse tapping keys, 3s., etc. etc. etc. N.B.-Mr. Portland Stocks 200 Wireless PartsThree days' approval against cash, or please call. CRYSTAL SETS IN CABINET Writefor detailedpricelistofallgoods.-E. J. Complete with 4,000 ohms Phones, Aerial, etc., iiiiiii~110111010.11110404110110101110111101101110110Galpin, 16, Loampit Hill, Lewisham, S.E.13, London. £4, cash withorder. Lt s Without Phones, £2 10s. B.A. Screws, Nuts, and Washers, assorted gross, Or on easy payments, £1 with order and 5s. per week 2s. ;list, 2d.-J. H. Bennett, Station Road, Willesden VARIABLE CONDENSERS, any capacity or type. A PERFECT DETECTOR Junction. (47 r COIL HOLDERS, CRYSTAL DETECTORS. All About Wireless.-Send for Booklet, 64 pages, FILAMENT RESISTANCES. INDUCTANCE 3/9 FOR WIRE CONTACT withmanyillustrations," Wireless Made Easy." STUD BASES, SWITCH ARMS, etc. POST Simple,conciseexplanationofwirelesswonder. Send Stamp for Lists.Our Prices will astound you. CRYSTALS How to make and fit up at home.Post free, 6d. Save money by dealing direct with the Manufacturers. FREE stamps.-TheCityWirelessandElectrical Depot Trade only supplied on small Brass Parts DOUBLE BALL JOINT (Dept.J),17,Hatton Garden, London, E.C. Reg. Design No. 691568 Five Wireless Sets Given Away!Particulars, 3d.- T. W. HALL & CO., Manufacturers, TEMA.' NVireless Department, Hardington, Yeovil. [zo r 58, HARDMAN ST., MANCHESTER. MICKELWRIGHT, Ltd. Buzzers.-Speciallyconstructedinstrumentsby ALPERTON, WEMBLEY, MX. which crystals can be set for reception, zs. 60., post free.-Fra'hk Hooydonk, Hornsey Rise, N. I9. 128 r Wanted,allwirelessparts,weeklyquantities STEEL TUBULAR MASTS directfrom factory;alsolaudspeakers, _phones. SCIENTIFIC APPLIANCES Dtlio4 SzaHsItins)i. F.lectrilftio Mlle& Sendconditionsandlists.-ApplyBoxin,c/o LESS PARTS and tiatertals at Lowest Prices. " Amateur Wireless." (5 s Call and see our immense stock or write for Information and l'rices. £6.Mark III. Tuner.Brand new. -24, Pollards In Centre of London, Top of ICintrway. Hill East, S.W.I6. [4s SCIENTIFIC APPLIANCES, " Work" Short-waveWireless 105. Easily erected and lowered by one man. 11 and 29, Sicilian Avenue, London, W.C.1. Receiver,£3 Light, strong, and cannot rot like wooden Stamp particulars. -26, Grosvenor Road, Wrexham. poles, and are fitted with Halyard and [2 5 Galvanised Pulley, SteelFlexible Guy Telephone Receivers Rewound up toi,000 ohms, Lines,with InsulatorsandStrainers, 4 Steel Angle Ground Anchors fitted with as. each ;2,000 ohms,7s.6d. ;cash with order.-M. E. ring for fastening guy lines.Painted and Hampshire, :39, Sydenham Road, S.E.a6. [3 s complete rowdy for erection.io ft., 158 ; EBONITE co ft., 25s.; 3c. ft., 35s.; 40 ft, 508.; so ft., 708. 1"--36" x 18",20/-;18" x 18",121-;is" X In*,5/6; 13e'ng the actual manufacturers we can therefore supply you at above keen prices, with prompt delivery, for cash with order. If X 9', 41.; 0" X 6',3/-; 4" X 4', 1/.; Ally size cut. Trade Inquiries Invited Knobs, solid ebonite 2BA and 4BA. 4d. each. Genuine "Brunet" phones. ABBEY ENGINEERING WORKS, WATTON, NORFOLK Valve holders solid ebonite, with 8 nuts, 1/. each. Extremely sensitive,asusedexclusivelyby Wireless supplies quoted for. Postage raid over 10/. French army and navy, 6 tungsten steel pole:, BAILEY & ROBINSON, 9 ESPLANADE, REDCAReach earpiece, 4,000 ohms, limited number at 25J. .EASY TERMS OR CASH

Further reduction. No extra charge for extended payments.L.F. Intervalve Transformers. Transformers, 15/0 & 20, Mallard Ora Valves 18/.. Double Hewlphones, Brown's, S erling's 4.000 ohms, 53/, muia,d's 4,000 Guaranteed highest efficiency, suitable for super ohms, 30/.. Best French 4,000 ohms, 25/. & 30/, British 4,000 All the News in regenerative sets.Ratio, 41 to I. ohms, highly sensitive, 20/. & 22/6.3 way Coilholders, 13/6 & 17,6, 2 wa7/6,Single Holder 2/6. Honeycomb Coils list, price a Nutshell in according to wavelength.Variable Condensers, complete sets of pins, CONDENSERS, the last word in efficient top and bottom, cox 8/-, 00e5 6/6.Accumulator, 4 volt ao amps, design, aluminium frames, all vanes rounded and amps, 201., Soamps.40;.. H. F. Battery.3ovolt TA, Se volt 15/.. Polished Mahogany Cabinet, with Ebonite Panel, drilled, for Single polished edges, 4" aluminium earthing plate to Valve Set 8 by 6, 10/., two Vales, xo bye, 15/6, three Valves r4by `the DAILY GRAPHIC avoid hand capacity, 3" bevelled and engraved 2.1/. and terminals.TermsOne-third with order, balance in six fortnightly payments. Carriage paid on all orders over 40!.. Money dial Tom for panel mounting, £1. returned in full if not completely satisfied.Other accessories for cash at lowestprices. The Perfect ACCUMULATORS, 6v. Go AMP.Celluloid G. RUSH, 119, Sutherland Avenue, London, W.9 Picture Paper Cases, 37/6, carriage free. INDUCTANCES, wound 22or24gauge, 12 x 4, 4/6. TELEPHONE: CITY 2972 ASK BASKET COILS, set of 7, 200/30,000 metres, 6/9. Ltd., "A. W. 3 -COIL HOLDERS, long handles avoiding A. MUNDAY, capacity, 13/6 each. for 59, WATLING ST., E.C.4, 45, EASTCHEAP, E.C.3 List of Every other accessory stocked. (One door Queen Victoria Street, :: One door Queen Street) Technical -- SEND FOR LIST.--- PAGET, 32, Glenthorne Road, Aerial Wire, 7/22 copper, 2/9 100 ft. Books. Hammersmith. Contact Studs, complete with nut, 5d. per dozen. RELIABLE RECEIVING HEADPHONES Ivorine Scales, 0-180, 3d. each. 4,000 ohms, double bands, complete with flex and tags, BROWN'S 4,000 ohm Double Head at 20s. each, post free Phones, 30/- per pair. Cash with order. Ex stock.Every instrument guaranteed. THE SOUTH WESTERN WIRELESS SUPPLIES CO., French 4,000 ohms 20/- per pair. 382a, Merton Road, SOUTHFIELDS, LONDON,S.W.I8 E 11111111111011111111112111MNIMMINIMIIIIIIIIME1111111M111111111MISIMIIII 771111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111IMMIII11111111111111117 DECEMBER...... 9,1922 ..... 631...... enuttattAViretess

ELWELL High Power ;111g,*(///////laiVc\WII/1/1/1)111)))41, Wireless Stations

Oxford

Cairo

EP;

Northolt

(1) The self -tightening bull -dog grip 4 Horsed fitted tothe Elwell plug enables

telephones or loud speaker connec- BULL -DOG GRIP Island tions to be changed in a moment.

CONNECTORS

(2) By the terminal adaptor, the bull- Eiffel dog grip connector can be added to Elwell patented self- Tower any existing terminals. , tightening grip fittings 4 are a big convenience. (3) For fitting to the face of a panel this ons pattern is recommended.It com- bines a standard terminal for fixed Without soldering, connections with a bull -dog fitting for corms:Lions which you require tightening of nuts or to change. V-4Nantes (4) A series connector with a bull -dog screws or the useof grip at each end.Invaluable for connecting telephones in series. anytools whatever, electrical connections Rome

(5) The series connector in use.Tele- canbe made, broken phones can be connected in series in an instant.No amount of pulling can break the connection.It thus or changedin a a oids those annoying interruptions &' others caused by involuntary movements. moment. <>

Moreover, theconnections when made areelectricallyperfectand

self -tightening. The more youpull them the tighter they

grip. Buttheycanbereleasedinamoment whendesired.

Ask tosee them at your wireless dealer or write fordescriptiveleaflet.

C. RadioEngineers, F. ELWELL, LTD.,

CRAVEN HOUSE, KINGSWAY, LONDON, W.C.2. Telephone :REGENT 421

000 Cntateur WireS3 632 DECEMBER9, 1922 Radio brings it: MAGNAVOX tells it MAGNAVOX THE WORLD'S FINEST LOUD SPEAKER

T0 enjoy and obtain the greatest possiblesatisfaction from your Wireless Receiving Set, equipit with a Magnavox Loud Speaker.Hear the voice of the singer faithfully reproduced, the perfect intonations of the lecturer,or No. R 1282 the natural sound of music.The introduction of the Magnavox Loud Speaker foruse (18 in. Horn). with Radio Re6eiving Sets marks a most important development, and will be themeans of making broadcasting extremely popular. INQUIRIES INVITED. Vo be obtained from all Dealers or direct from the Manufacturers and Sole Licensees

STERLING TELEPHONE & ELECTRICCO LTD.,9 Telephone House, 210/212, TOTTENHAM COURT ROAD, LONDON,W.1 Telephone : Museum 4144 (7 lines). Telegrams: " Cucumis, Wesdo, London." NEWCASTLE -ON -TYNE: WORKS: CARDIFF: .0. 9, Chwering Place. Dagenham, Essex. 8, Park Place. IMMEDIATE We guarantee that all Broadcast Radio Apparatus sold by us conforms with DELIVERY the conditions of the Broadcaster's licence issued by the PostmasterGeneral.

I 7 iiin_flfiel,,,,,549,1114.. ..VII2V!1,11,511,1,1rrrlf11 i..

#674444 elLeretie tkeeiti "aktvieriei Your electric light catches the wireless exactly as an aerial does. Plug a "Ducon"into any lamp holder or wall socket, connect it to your wireless receiver and you will receive the broadcasting perfectly. USE A "DUCON" and you don't need an aerial

"Ducons" areperfectly safe-each oneistestedto 5,coo volts, they consume no current and do not affect the electric light in any way.

The

isobtainable from leading wireless dealers,electrical contractors and stores, or direct from the makers. Dealers not yet stocking are invited .to write for Tracle Terms Over 50,000 in use The Dubilier Condenser Co. (1921) Ltd. Ducon Works, Goldhawk Road, Shepherds Bush, London TeNhone-Ileemmersmith 10E1.Telegrams-Hiratcon, Phone, London

Printed and Published in England by CASSELL & COMPANY, LIMITED, Ludgate Rill, London, E.C.4.Sole Agents for South Africa, CENTRAL News AGENCY. LIMITED. Saturday, December 9,1922 33 Forminga WirelessAssociation (see page 645) Thirty= Teo° Pages

No. 28 SATURDAY, DECEMBER 16, 1922 Price 3d,

CO\TENTS CONTENTS

How to Record Rectification by Signals Crystal t2 Coil -winding The Valve as a Apparatus Generator

Making Contact Low -frequency Studs Amplifying Sets

Wireless as a Profession Bending of Wireless Waves Radiograms Club Doings On Your Wave- length Correspondence Telephony C Fourvalve Cabinet Receiving Set Transmissions (W. R. H. Tingey) Information Bureau emateur Wire -toss 634 DECEMBER 16, 1922 , (9):MITCHELFONES CONOMIC LE CTR,I LTD.,C Are not a spasmodic production to meet a sudden demand, but have been on the E Have YOU tried the market for over three months, and during this period 27,000 have been distributed

" XTRAUDION " VALVE ? to thetrade, and consequently we have the latest and best development of not been able to offer them direct to the the 3 Electrode Valve. retail buyer. a RECTIFIES, OSCILLATES 2,000 per week are now available, and we announce AMPLIFIES Its Mechanical Construction DELIVERY FROM STOCK makes it a stronger and more lasting You postyourorder,orcallatour valve than any other. premises and get them at once.Think

The Filament consumes well under what this means to you-you, per haps,w who half - an - amp. at 4 volts.Anode have been waiting and are stillwaiting.

Potential, 50 volts. Standard resistance 4,000 ohms, double headgear with Its Amplifying Properties are double headstraps,comfortable,highlyefficient, wonderful and its freedom from noises and foolproof a revelation. Send for Descriptive Leaflet. 251- per pair:

E 151- 15/- Special Terms to Traders and deliveries

that will surprise you. PRICE PRICE PATENTS

PENDING MITCHELLS Electrical & Wireless Ltd., We publish the most complete Wireless Postal Address: McDermott Road, Peckham, S.E.15. Catalogue obtainable.36 pages, profusely Retail Address: 188, Rye Lane, Peckham, illustrated, and many usefulcircuitsfor Head Office 10, FITZROY experimental work. Mailed to any address c'Phones: New Cross1540/1541. SQUARE, LONDON, W.1. on receipt of four penny stamps.

Showrooms : 7 elohone : Blanch Showrooms S. Works GREAT BRITAIN'S GREATEST WIRELESS STORE-4k) 303, EUSTON ROAD, N.W.1. MUSEUM 1055 TWICKENHAM

"HERTZITE" HEADPHONES!! OUR GREAT CRYSTAL FOR BROADCASTING Buy French Headphones SIMPLE TO USE. NO BATTERY; REQUIRED Now and Save s.d. Price 2/6 post free Headphones Mounted in our Patent Detector, 5/6, post free of French manu- factureareseldom equalledfor This Crystal was named and introduced by us. sensibility and workmanship. Efforts See you are not taken in with some substitute. are being made to prohibit importa- tion,Therefore buy now. We can give the best Wholesale Terms for all Crystals Owing to the present favourable VALVES: "ORA," " XTRAUDION," "C.V.C.," Er "R.M.R." 15/. each rateofexchange, wecanoffer various makes at the following ex- RUSSELL -SHAW traordinary prices 38, Great James Street, Bedford Row, W.C.1. List T otal Res Retail No. Make' in ohms. Brief Specifications. price.Postage.

STARTLING REDUCTIONS 201 Picard 4.000 Mouldedebonitereceivers, Ebonite Condenser Dials, Engraved 0-150' and doubleduraliumstraps, 2,13 fully ad Instable - ...... 21'- 9d. filled white with Knob, Brass Bush and Set Screw B,000 ... Dial only ...... 116 202 III Ditto ...... 22,6 9d. 203 2,000 Single Receivers only, com- 411notslIZAIN,i1sW. Aluminium Condenser Vanes perdoz. -. 6d. . Spacer Washer, small3d.dos. ; large 4d. doz. plete with cords .. .. 8/- 5d. 204 Brunet 4,000 Aluminium receivers, double Knobs, with a BA Brass Inset ... 3d. A.E.G. and Halske Valves for recti. oxidised steel straps, fully rGrid Leaks (enclosed), a meg. 1/- tying and amplifying (tested) 7/6 adjustable, extra lung Grid Condensers .. 16 Crystals (special selected), Sornite, cords ...... 23/6 9d. Filament Resistances 316 Zincite, Galena, Silicon, Carbon. 205 Thomson- 3,000 Highly polisheddetachable Crystal Cups with Screw ... 3d. undum, Copper Pyrite-, Graphite, Houston receivers, single nickel - Fusible Alloy, per stick 4d. Tellurium, etc. ... 6d. platedlightwidesteel Inductance Tubes, ra X 3' ...... 6d Egg Insulators, Green ... 4d. spring strap. Particularly T2' X4.°.. ... 9d. Reel best quality... 3d. suitable for ladies.. ... 23/6 9d.

... - Hellesen 36 v. Batteries with Tap- I2'x 5' ... 206 As above, but with'double it I2*X 6' ...... 1 3 pings and Wander Plug... 3 6 straps, fully adjustable... 24'6 9d. Sliders and Plungers ... 6d. Essex r5 v.H.T.Batteries... on As above, single strap ... 24 6 9d. Ebonite leading In Insulators i, 4,000 Sq. Brass Rod, ta" x 1' x 1"...... 4d. 208 JP As above, donbie straps ... 2516 9d. Enamelled Wire, 23 gauge, lb. ...2 Peril. on Detectors on Ebonite Com- JP Aerial Wire, vas, Stranded, too' plete with Crystals ... 4/- Valve Holders, Screwed Legs 9d. "Ubique " Crystal Set Complete... 15/. Satisfaction Guaranteed. Liberal Trade Terms. Send for List to -day, DELIVERY BY RETURN GUARANTEED Postage extra. (PARIS and LONDON.) oir Shwaroonas 42, JENNER ROAD, 49LISIFT9, GOOVENST G GNREENIL" R. THE ESSEX WIRELESS CO. E, W. JOANES,NEWINGTON,LONDON,STOKEN.16 Telephone-%VANRTEAD 749. (1min.fromStitt:ion, G.E.R.) X35

No. 28 December16, 1922 Recording Wireless Signals Constructing a Simple Device for Printing Morse THE inability to read Morse places many terminals v by a piece of very thin coiledwheel by a pinion and large gear wheel. amateurs under a great disadvantage,copper wire.The other contact c (also.The pen consists of a short length of glass for many of the important communicationspreferably of carbon) is mounted in a smalltubing drawn out into a fine point; the are carried on in the code, as for long-cup, its pressure on B being regulated byupper part holds a small quantity of ink, distance communication telephony isout and is therefore fitted with a cork. ofthequestion. Thedifficultyisin If the moving parts are made light and memorising the code, and long practice 11111111111111111111111' littlefrictionis allowed, the inker can isrequired in order to be able to take record automatic transmissions at quite a down the signals as rapidly as an expert good speed. operator transmits them. Fig. 4 shows the method of connecting To obviate these difficulties, and also to up the apparatus which will work quite keep records of press, etc., the writer uses smoothly. provideditiskept free from the instruments shown inthe diagrams, vibration. which automatically. printsthereceived The signals from the receiver on pass- signals on the familiar Morse. tape, when ing through the telephone vibrate the dia- fig. 1.Dancing -contact Relay. they can.. be decodedslowly. The phragm and contact B.Contact C is ad- apparatus can easily be made with few justed so as to keep a light contact with B, tools, and the necessary components maya screw fitted with the knob D, the wholeand the rheostat varied until just sufficient be purchased for a comparatively smallarrangement being similartoacrystalcurrent is allowed to pass the contacts in sum.It is easy to adjust, and if not dis-detector.Contact c is connected to theorder to keep the relay contact on the turbed will go on working until the paperother terminal Y. spacing stop,thatisso that the 4 -volt is exhausted.Its only disadvantages are Across these two terminals is connectedbattery does not actuate the inker. that unless the signals are very strong ita Weston moving -coil relay in series with On the arrivalof the signal the dia- will not work With less than three valves,a small dry cell and rheostat.The Westonphragm vibrates, moving the contacts and

VOLTS Fig. 2.-Weston X Relay. lip ( 3 VALVE RECEIVER 111: RELA1 il1 Fig. 3.-Morse Inker. ii',1119

vni.T5 CONTACT Fig. 4. ---Diagram of Connections. PRINTER

and as itis very sensitive to vibration itrelay (shown inFig.2)was purchasedthusincreasingtheresistancebetween is not portable. for thirty shillings, and it has now beenthem.The decreased current not being sufficient to hold the contact arm of the Fig. rshows the dancing -contact relayworking satisfactorily for nearly .ayear. that controls the current supplied by aThe small current from the dancing con-Weston relay back, the arm flies over to small dry cell operating the Weston relay.tactcontrols the current supplied by athe marking stop, allowing the 4 -volt ac- This dancing contact is the essential part 4 -voltaccumulator actuating the Morsecumulator to, pull down the pen on to the of the apparatus andisused by manyinker shown in Fig. 3. tape, thus recording the signal. American amateurs for similar purposes, The inker is of the usual type, driven Once adjustedtheinstrument works although the arrangement is different. A by asmall electric motor, but any typewell, but as before mentioned, itis very is an ordinary telephone ear -piece mountedof inker will answer provided the magnetssensitive to vibration from traffic, etc., and on a- suitable base, and leads from itsare wound to a suitable resistance.Themust therefore be installed in a quiet part terminals are taken to the two terminalsone shown is home -constructed.In orderof the house. X. B is a light carbowcontact, the smallerthatthetape wheel may revolvesuffi- The small expense and trouble incurred the better, fixed on to the telephone dia-ciently slowly;thebeltdrive froM thein its construction is amply repaid by the .pbragm andconnectedtooneofthe motor worksr sepaiaie shaft driving- theresults obtained. K. U. 0....,Wiretess 636 DECEMBER 16, 19211

101 16 la tO1 .,, Rectification by Crystal tr, y

Pi

C'i h [ci Ell [P]

[0] 6

16 ll [6 inM11 [0] E6

T1 4-11

P1 VI

16

B.1.41. Crystal Receiver iBrilish1 nomson-Houston Co., La). Empire Crystal Receiving Set (A. C. Cossor, Lid.). 11 16 10 IA

THERE are many types ofcrystals,these crystals in the first class being moreing from zero and rising to their maximum but they can all be divided into twoeasily explainable than that employed withvalues. distinctclasses. Firstly,thosethroughthose inthe second classwill be dealt Now considering one trainofoscilla- which an increase in flow of currentiswith first. tions, we will suppose that the first alter- proportionateiVI to an increase in potential All crystals have the property-exactlynationrisesinvalueto.3volts,so differenceacrossthecrystal. Secondly-,why isnot known-of allowing a largeplotting this on the graph, as in Fig.1, those through which, after a certain volt-amount of current to pass through themwe see that it causes a current rising in age has been applied, the increase of cur-in one way and only a very little in thevalue up to 6o micro -amps to pass through rent is out of proportion with the increaseother way. the crystal.The next alternation being in potential difference.Hence itissaid To explain theresultofthispheno-negative in direction causes current rising that those crystals in the first class obeymenona graph ofthecurrent -voltage to only .5 micro -amps to flow in the oppo- Ohm's law, which states :" The currentcurve of a typical crystalis shown (see sitedirection.The next positivealter- nation causes a current to flow rising up 100 toso micro -amps.The following alter- -r-VOLT-AMPERE CURVE nation being again negative in direction t4rCRO- 80 causes only .4 micro -amps to flow, whilst AMPS the next positive one produces a current 60 CONDENSER CHARGE Al END OF EACH 1 RAIN rising up to 40 micro -amps.And so on Of WAVES to the last positive pulse which makes a 40 varying current, having a maximum value to 20 of 6o micro -amps, flow through the 0 crystal. Fig.2.-Receiver Circuit For one train of oscillations we thus have pulsesofcurrentof a large 4 .5 Using an "Ohm's Law" oIb2 b3 b4 b5 Crystal. value ina positivedirection and ofa TIME very small value in a negative direction. Fig. 1). Along the horizontalaxisare OSCILLATORY plottedvaluesof E.M.F. measured inThe Blocking Condenser VOLTAGES TIME volts, and along the vertical axis current Inacircuitemployingtheordinary Fig. 1.-Characteristic Curvevaluesmeasuredinmicro -amps. Thetypes of detector a blocking condenser is of Bornite-zincite Crystals. resultant graph will be one showing theplaced across the telephones asinthe increase in current for a certain increasecircuit shown graphically in Fig. 2.This in voltage, and will be in the form of acondenser will be charged positively and flowing inany circuitisequaltothestraightline because an increase in onenegatively by the rectified current.Owing potential difference between the ends ofisproportionatetoan increaseintheto the high frequency of the alternations that circuit divided by the total resistanceother.The type of crystal we are con-the condenser will only be able todis- of the circuit ; and that those'in the secondsidering is used in a circuit such asis charge at the end of each train; this dis- class do not obey Ohm's Law. shown in Fig.2, whereitisseen thatcharge, being the net result of the positive Included in the first class are such com-no steady voltageisplaced acrosstheand negative alternations, will be positive binations as bornite-zincite (perikon), sili-crystal.Therefore the alternating voltagein value.This will be seen to be so on con,whilstthecarborundum-steel com-due to the oscillation in the aerial is thestudying the graph,Fig. 1,where the bination is included in the second Hass. only voltage which affects the crystal, sorectified currentisplotted against time. The method of detecting employed withthey must be plotted on the graph, start - (Continzted on page 651) ,. DECEMBER; -1922 637 mateur 14141ms

fth [Eh I6 .16 A Coil -winding Apparatus

_ -77._,TitsCE122rtg=lf225][toritIrl;li.TuTrq2

THE apparatus shown by Figs. and 2 coil fads to take the spindle.Insert the For the traveller a piece of 14 -in. square was designed for amateurs who desire spindle in the coil and screw up tight, rod 5 in. long is required.Make a hack- to wind cylindrical coils easily and have using two nuts each end (one nut actingsaw cut at the top end, to run the wire not access to a lathe. lock -nu through, and tap it 4 BA about 3 in. from Procure an old highly -varnished thin the bottom end. , cardboard advertisement which is roughly Screw the traveller ontoitsspindle 9% in. by 14 in.Bind lengthwise in a and add two nuts to each end.Insert the circle, glazed side out, and glue a butt - traveller spindle and spindle with the coil strap inside along the scam, leaving the holder between the two end pieces and latter Y, in. short of each end for the in- then screw the end pieces on to the two sertion of the circular end pieces of hard bottom pieces. wood. Place one gear wheel on each spindle, To wind 24 S.W.G. enamelled wire the securing them by the small set screw pro- following material will be required :one vided,and then mesh the third gear wheel rod screwed 4 BA 12 in. long; one spindle Fig. 1 loosely on a wood screw and tighten up 12in.longpassing throughthecoil all round with double nuts.Attacha holder;threelargesize" Meccano " handle to coil spindle and the apparatus is wheels; two wood end pieces7in. by complete. 5 in. ; two pieces of wood for the base- The sizes of the coverings on wire vary one 3 in. wide and the other t% in. wide. Fig. 2 with different makers, but almost any wire Take the 7 -in. by 5 -in. pieces and bore can be wound by first windingrin.of two holes in them about 2'4 in. apart to turns on a lead pencil and counting the take the traveller spindle and coil spindle. number of turns and selecting the thread Screw a thread at each end of the coil Figs. 1 and 2.-Plan and End Elevation of giving that number or nearest less to the -spindle.Bore a hole in the centre of the Coil winding Apparatus. inch. J. M. W

E2 A Cheap Variable Condenser 1P1

THE accompanying drawings illustrate The capacityisvaried by sliding theeach side of .the wooden strip.A spring the method of constructing a simplepart C over or away from D (see Fig.1). letter clipis then connected by a short variable condenser which, besides beingThe measurements shown in the drawingspiece of flexible wire to terminal B and easytoconstruct,will be found to behave been found the most convenient byclipped on to that part of the tinfoil which equally as useful as the expensive boughtthe writer, but, of course, these may bepasses over the wooden or ebonite strip G. In this way electricalcontact with the FLANGED STRIP moving plate of the condenseris easily V / E made. V-4 The fixed part D of the condenser is tin- t AlJ Fig. 2.-S etifit of ..I Hanged Strip. C p.::,0

B 0 \,,,......

I0" F g. 1.-Top Elevation of Condenser. ig. 4.-Complete Condenser.

modified. The base and flangedstripsfoil glued smoothly to the base and covers marked E (Fig.i) are made quite smooththe area shown.This tinfoil is connected withglasspaper. Thesectionoftheto terminal A. flanged stripsis shown by Fig.2. The The flanged strips E are so fixed al to construction of the moving plate C mayallow the moving plate and glass to slide be seen from Fig. 3.For the dielectric aeasily backwards and forwards.K is a ,,,i-plateglass negative (which has beensmall ebonite knob for moving the plate. TINFOIL ig. 3.-The Moving Plate. thoroughly cleaned) is used.G (Fig. 3) is The terminals A and B are mounted on a small strip of wood or ebonite and is ebonite screwed down at each end to variety. A brief description only is neces-glued on to the glass. A piece of tinfoil isthe strips E.The complete instrument is sary, as the sketches explain themselves. laid over this and attached to the glass atshown by. Fig. 4. F. D. C. emateur Wirdes5 638 DECEMBER 16, 1922 Jr:f.:.t.:2,-LTJE.7-ffic:4-LLT5L-t-;3,-141'.T-E] increases the downward thrust of the plate current and so carries it past the normal, IF] down to the lowest limit or zero.Then All About the again the transfer of energy ceases and LdontactStuds 4) thecurrentcommencesaccordinglyto pi regain its normal value (corresponding to Valve IX the filament current and the high-tension Made from yi on the plate), and so the process continues. ...i AS A GENERATOR Vi In reception by the heterodyne method Vi the localoscillationsso created interact Screws [0, 4-) H. T GENERATOR I T is frequently desirable that the tube + NA /HEN it is desired to make up one's should generate sustained oscillations- V V owncontactstudsthefollowing for example, when it' is used as a trans- II- idea willbe of service. Cheese -headed mitter or as a receiver of undamped or screws must, Of course, be used, and, as C.W. signals by the heterodyne method. the sizes of these vary greatly, no definite The coupling of the coilsA and B(see dimensions can be given for making the Fig. 15, p. f to) is then increased until the. jig.Itisthought,however,thatthe reaction issufficient to set the plate cur- diagrams Figs. ito 3 will give a clear rent surging continuously (see Fig. 16). impression of What is required. Referring to the illustrations it will be interchange of (Energy seen thatthe jigiscomposed of three The action is precisely the same as that portions.The material used throughout previously described, except that in this is mild steel.A and B (Fig.1) should be case the upward growth of the plate cur- slightly less in thickness than the distance rentislimited, not by the imposition of between the base of the screw -head and each successive signal half -wave, but by the bottom of the screw -slot.Two fixing - the physical dimensions of the tube itself. H screw holes are drilled in each in the posi- Theoretically the interchange of energy tion shown, and these are countersunk so between the grid and plate circuits shouldFig. 17. -Thermionic High -frequency Generatorthat the heads of the fixing -screws will be continually increase, and in time become for Telephony or C.W. Transmission. slightly below the surface.When com- sufficient to create oscillations of infinitely pletedbothpiecesarecase-hardened. large amplitude in the plate circuit.Inwith the incoming signal oscillations so as to create a "beat" effect of audible fre-The reason why the jig has only been practice, however, the plate current cannot designed to take two screws at a time is exceed the saturation value of its charac-quency.This is rectified by the grid leak and is detected in the phones. because, if A and B were made longer un- teristic curve (see Fig. if), nor can it sink evenness of surface might be caused by below zero value, and so the extent of theThe Thermionic Generator the metal warping during the case -harden- plate variations is limited by these factors. Fig.57 shows a thermionic generatoring.c should he at least 3.1,in. thick, so It may perhaps be asked why the firstfor use as a telephone transmitter or for,that the jig may have a firm foundation. impulse on the grid does not thrust theC.W. telegraphy. The regenerative actionThe holes for the fixing -screws are drilled plate current up to its maximum value andtakesplacethrough the tightly -coupled and tapped, so that, while being coinci- keep it there.The answer to this is thatcoils A B. The plate and aerial inductances dent with those in A and 13, they are at the value of the E.M.F. transferred fromform an auto -transformer. such a distance apart that the slot formed the plate to the grid is measured by the The action is precisely similar to thatbetween the plates A and B will be just rate of change of the magnetic flux.Thisdescribed in the_ heterodyne receiver, ex-equal to the diameter of the heads of the is a maximum at the steepest part of theceptthatgreater energy variationsarescrews to be made into studs.The holes platecurrentcurve. Asthecurvenaturally concerned in the case' of trans-forthe reception of the shanks ofthe approaches the apex, this rate of changemission. The plate tensionissuppliedscrews are drilledinthe centre of the diminishes,whilst atthe moment itisfrom a D.C. generator of suitable voltageslot, and should be clearance for the size actually at the apex the current is momen- (say5,zoovolts). Signalsaresent byof the screws used. tarily steady (there is no rate of change),means of a key x in the grid circuit, which Using the Jig Fig. 16.-Variations in the Plate Current starts and stops the oscillations, the dura- of an Oscillating Tube. tion of each C.W. wave train radiated When in use the jig is held in the vice. from the aerial corresponding to the MorseThe screws are inserted in the holes in 1,,,c-rEFtSTIC intervals. the slot, and, after making sure that they L CYI' For transmitting speech, a microphone A B circuit M isconnected through a trans- former tothe gridcircuit as shown, a 111111201111111 condenser c forming a shunt for the high - Fig. 1 ti frequency currents.The action of the circuitistosuperposeonthegrid, f:=3 voltage -variationscorrespondingtothe Figs. 1 to 3.-Making low -frequencycurrent -variationscreated Contact Studs from by speaking into the microphone.These TIME Fig. J Screws. arereflectedintheplatecircuitand so that the transfer of energy ceases andcausetheamplitudeofthecontinuousare firmly seated, are filed off flush with the plate current commences to fall to itswaves fed to the aerial to vary.At thethe surfaces of the hardened plates.The normal value (as shown in dotted lines).receivingendthese"carrierwaves "latter will not be "touched" with the file, Immediately this reversal sets in, however,are rectified, and the superposed voice -and uniformity of contact surfaces will be anewmagneticlinkage -variation isformvariationsarerevealedinthethe result.An oldfile should be used created between thecoilsA B(Fig. 15) phones. D. ALcAsE. as the hardened surfaces would soon ruin which sets up a reverse E.M.F., and this (To be continued) the teeth of a new one. T. mcG. DECEMBER 16, 1922 639 '7XeW

as-afts MULLARE PHONE. Specially made forthereceptionof wireless broadcasting, Mullard 'phones arethoroughlywellmade andfit comfortably to the head, etc. British Manufacture Thetwohighresistanceear -pieces (4,000 ohms total) are flexibly attached tothefullyadjustable,double head bands. The setis nicely finishedin nickel -plate and supplied complete with standard flexible cords. TYPE A, Send the coupon to -day to secure im- 21/- mediate delivery. Thesetelephonesare made by the TYPE B, makers ofthe famous " ORA "valve - and Mullard valve accessories. 25j

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b.") . ,,, q' 1111111111111111111119 1610 161 0 411111 1111111111111 HIM 111111111; .0c'e'c.b. ' 4,,..4.4' e1b* ..-S,'c ' ). 41.4e, oef! 0.25. 0.c. t,\.\eb c>c"4.,:e> 0.* e

'? s'''' 4' .... 4a WarOfficeRgyalAirrorce&PostOffio3, ,' 0-.t-..,,2> '°6e, c.be'z,,c,0* -e' be44\5, . cy c0 cp ,....c., 0 A.0'., Telephone: Codes: 0, Telegrams: '.:;;;e', 4$4'''z''S*''''' '. Battersea ./...' ABC (5 Ed) 'Radiovalve, Hammer' ...' 0 .0 c,oc,s.,l'e'4' 1068 Bentley's London.

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MIAR >.:,.;4 gellittanue 0.32LD2'..) N) 4)sti 640 DECEMBER t6, 1922 entateurWireles3 T.M.C. Wireless

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Make it a T.M.C. Wireless Receiver and strike a new note.T.M.C. offers you a wide selection of fully approved, British Broadcasting Receivers, from simple Crystal Sets to Cabinets de Luxe The illustration shows the- T.M.C. CRYSTAL SET NO. 2 with PATENT "EVERSEV" CRYSTAL which needs no adjusting.Call and choose your Present to -day. If you cannot call, full particulars will be sent on request. The Telephone Manufacturing Co., Limited, 68, Newman Street, London, W. r, Tel.: Museum 5581 Wehaveengineersin everylargetown, who install the wirelessto your satisfaction. TM London, Manchester and Birmingham ntakesVireim worth while are Broadcasting Now. DECEMBER 16, 1922 641 mateur Wireiess BUY YOUR XMAS GIFTS NOW ! FURTHER GREAT REDUCTIONS IN PRICES ALL GOODS SENT POSTFREE "Igle Headphones BEAVER Splendid Crystal Complete Set of Detector CONDENSER Mounted on Ebonite. PARTS

contains: Ebonite Top and Bottom Plates, Machined Aluminium Moving Plates Aluminium Fixed Plates 1 Square Centre Sp"ndle POST 4,' 3 Stay Rods, screwed both ends FREE Large Spacing Collars Small Spacing Collars High-c.assFilamentkesis ances4/- Bronze Coil Spring 100 ft. Aerial Wire 7/22 Stranded H. D. Copper- the best 4000 ohms total EboniteKnob.drilledand screw fitted ... 3/ 10 Best Quality Switcharms 116 Resistance. Brass Nuts forCentre Spindle Double Headband. Small Nuts Valve Holders Best Quality Ebonite ... Guaranteed highly efficient. *0005 MF. 8/6 1 '6 Complete with Cords.Ball *00075 MF. . 9/6 Best Insulating Composition 10d. andsocketjoints ;highly Condensers '0002 1/6 polished nickel cases ;best '001 MF. 11/6 ID DD '003...... 2/9 Tungsten steel magnets. 001S MF. 131. Chemically engraved Scales 0-180°, 31d. BEAVER COMPLETE CRYSTAL SETS Beaver " MIDGET " Crystal Set No. 5 De Luxe Set

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01111i11111111% UMUMUNHHHIDINWHHHHOUUM11

I0UNNEINIIIMINNIO C=11 The Ideal Xmas Present.Length 61 in.x 4 in.Absolutely guaranteed. 15/- ;complete with 4000 ohm ear -piece, 30/-. Comprises Inductance Coil 9" X 3k", with waxed interior to prevent No. 1 unassembled 151-No. 2 unassembled 20/ - sweating, wound 24 -Standard Wire Gauge, Bronzed Wire, heavily shellaced andvarnished. Beaver de Luxe CrystalDetector with Crystal, Highly efficient Blocking Condenser, 2 brass Rods. Special No. 3 assembled 24/- ready foruse pattern Slider and Plunger, concealed Insulated Wiring, all necessary Complete with Splendid Tested andGuaranteed 4000 ohm Terminals and Tabs, the whole mounted on polished Mahogany base, Phones, 45/. with fluted edges. A Highly Efficient and Guaranteed Set. No; 4 unassembled 304: - Assembled 50/- ready for use Complete wi'h Splendid ested and Guaranteed 4000 ohm Complete withSplendid Tested Guaranteed 4000 Phones, 70/ - Phones, 50/. (Passed by Postmaster -Gen, rat, G.P.O. Regd. No. 198) BEAVER ELECTRICAL SUPPLY CO. Telephone: GERRARD 1900. 109, REGENT STREET, LONDON, W.1. Special Terms to Trade.All Cheques and Postal Girders to be crossed London Joint City and Midland Bank. mateur Wirehss 642 DECEMBER 16, 1922

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Acentic 1316 Wholesale and Retail Distributors forMessrs. BURNDEPT, Ltd.Same Trade Discount Allowed as by Manufacturers. AGENTS. London: H. V. ALBROW, 56, George Street, Baker S. Wales:SOUTH WALES WIRELESS INSTALLATION Street, W.1. CO., LTD., 18, West Bude Street, Cardiff. Gi08.: BRISTOL WIRELESS CO., 62, Cotham Hiil, Bristol. N. Wales, Lancs., Ches. & I.O.M.: THE " ALL- BRITISH " WIRELESS MANUFACTURES CO., LTD., Leicester: WALTER ROWE, LTD., 9(3, Granby Street, 18, Vauxhall Road, Liverpool. Leicester. Dtt,EMBER 16, 1922 643 eltlateur Wirdes,

aval,elot My Favourite Amateur Valve HAVE youthe very best modern stuff.F L ended atSome have taken Transmissions noticedt h e5.5o with his customary "Bon soir, mes- Non-stop Seven - to the shorter amazing strengthdames; bon soir, messieurs." Ten minuteswaves, others have Oscillation and the hours' Concert of the spark trans-interval to adjust a high-tension connec-changed their American Tests missionsfromtion which showed a disposition to crackle. One Vies times. no American ships ? At 6 p.m. to the minute, 21. O's chimeslongerhearsthe 21VI T to C Q Some of our coas-announced that he was on the spot.Onlypleasantbuzz of talstations,suchthe first news bulletin from him, but theconversation that as G N P and G B; are powerful enough topromise of a concert later.6.t5.-Man-used totake place every evening and make the headset uncomfortable wheneverchester, in full song.More good musicmost of the day on Sundays On round quite a small number of valves is in use.until an entertainer with some sort of aabout 40o metres. We all of us owe these But if ever your ears are suddenly blastedrecitation came on.I couldn't get himenthusiasts a deep debt of gratitude for into temporary deafness by a callthatvery, well-Manchester is 200 miles away-what they have done for us in the past. seems to come from a million kilowattso went fishing.Surprised an amateurBut for them there would, on most even- station situated -in your own back garden,announcing that he was coming on atings, have been nothing at all to listen to you can be pretty certain that you are p.m. with music.Our old friend 20 Min the way of telephony. listening to the gentle cooing of one ofthis was.Are we going to get to bed at Uncle Sam's mercantile marine. If Ameri-allto -night ? * * * can land stations are of anything like the Birmingham was goingstrongat 7 same calibre it is no wonder that Congress o'clock.Transmission excellent, but still It is reported that hundreds of amateurs, is taking measures to suppress spark trans-that hollow sound, as though the roomfired by what has been done at Croydon, missions. from which the speech and music comesNottingham,Bridgend,Brightonand * * a'a' was absolutely bare.Why does Birming-Holyhead, are now burning the midnight ham say he is going to switch off for threetherm or watt, as the case may be, whilst My rectifying valve blew out on Sunday.minutes and then be away five or eight?endeavouring to pick up dulcet strains On any other day of the week it would beIt wastes our "juice."But we don't havefrombroadcastingstationsacrossthe the simplest matter to obtain another thatto listen to Birmingham, do we? ThatHerring Pond.They should remember, would have done the work in some kindhe was good enough is evidenced by thehowever, that others are engaged just now of fashion.But I fear that I shall neverfact that I stuck to him till 8 p.m. in trying to hear American amateur trans- be able to replace that old friend, the London again at 8 o'clock.Very goodmissions;itistherefore very important best rectifier that ever was.The secret ofindeed, and punctual. When Burrowsthat no set should he allowed to oscillate itsexcellencelayinitsslightlysoftof the clear articulation says that he ison short waves during the night hours, for character. With it mounted on the big sethaving a three minutes' interval, itis a'interference of this kind might easily spoil one could search round with a clear con-three minutes' interval, except when heimportant experiments.It must be rather science amongst telephony transmissionsmakes it two minutes fifty-seven seconds.a blow to Uncle Sam that we have heard untilone found what was wanted, forViolin and piano and some excellent con-hismusicbeforehehasmanagedto there was never a sign of a chirp or atralto and tenor songs from London.At listen -in to ours.Don't worry about that, squeak whilst searching was being done.8.45 we decide that London may be verythough..It won't be long before American Your hard valves areallvery wellin good, but it isn't the only pebble on thepapers report, with headlines of vast size, their way, but forrectification purposesbeach. What aboutthat new Frenchthat Abinadab P.Joskins,thethirteen - they cannot hold a candle to those of thestation on r,soo?Perhaps there won't beyear -old son of the Sheriff of Sloshville, open grid type with a small residue ofso many fellows using reactance on thePa. (or perhaps Va. or possibly Ga.), has airleftwithintheglass. My lateaerial and flashing condensers on thatbeen hearing 2M T for weeks on a home- lamented was not,Iregrettosay,ofwave -length. Something has got to bemade crystal set that cost exactly 37 cents British make; in fact, had any memberdone about these ether -hogs.They aren'tto construct. of the B.B.C. seenitI should probablygetting much fun themselves because their SrSrSrSr have been hanged, drawn and quartered;instrumentsaren'tproperly tuned, and but it did the work as no other has everthey spoilthe pleasure of everyone for The Morse instructor was warming to done it,giving a far greater volume ofmiles around. his work with the beginners' class."The perfectly pure sound than can be obtained Yes, the Radiola people were there, andletter v, or vic," he thundered, "which you ivith any that has since been tried.Ifnointerferenceatall. Instrumentalwill hear used a great deal on Sunday one of our home makers will try placingmusic to start with, then some songs, andafternoons during The Hague concert, is on the market a valve designed speciallyan excellent 'cello solo.More orchestralmade up of three dats and a dosh !" for rectifying, "softish,yet able to with-work.Radiola ended at 50.5, and it was stand 6o volts on the plates without blue -curious to hear F L's time signals butting * a' *. glowing, he willfind thatitwill com-in on the last item, though he isr,000 Did you hear, by the way, of the post- mand a ready sale. metreshigher up onthe wave -lengthcard received at Writtle from an admirer scale. who had been motoring that way ?" I * a' At ro.21 the amateurs were getting busy.had hoped to call," so he wrote, "but Let me tell you of a non-stop seven -They keptit up untilmidnight, withwhen we got to Writtle it was an hour hour concert.The fun started at 5.15 withspeech and music.A seven -hour run,past lunch time and I was 2M T to C Q." F L booming through as though he waspractically non-stop. Too bad;stillWrittle was askingfor in the same room,Weather report first, * * 54* trOuble after his spoof chimes on a biscuit as usual, and then an excellent musical Amateur -transmitters have- been rathertin and 2M T bottles ! programme, vocal and orchestral, mostlyput in the shade of late by broadcasting. 7-mannoN. mateur Wirele-ce 644- DECEMBER 16, 1922

El) " A.W." Ideal Unit Receiving Set.IV THE LOW -FREQUENCY PANEL "

APASSING reference was made in theof them can be relied upon to. eliminatesion, for a certain amount of distortion will last article to some of the drawbacksentirelythe unwanted effects,but theyhardly affect spark or continuous wave that attend the use of low -frequency ampli-certainly make a great improvement.Yousignals, though it mars the distinction of fication; though these are serious, it must speech and spoils the tone of a musical not be imagined that this form of wave item.Gramophone records, by the way, ;Ii;irffr.lc..:::_l_.::::_-_-_-,_-_-_- _7..1"...., 4 are not ideal for testing purposes, since if

SECONDARY PRIMARY the receiving setis perfectly in tune the WINDINGS WINDINGS scratching of the needle on the surface of -;;NiditrOm) .0 000009 0 0(2922C2i").,,, the record can be heard, and may be mis- .\:--- /... L taken for the hissing that often betokens a ...... 0000.11 faulty grid -leak or the presence of self - :::71:7:71:::::::::.Bill:: ;p;i, oscillation. 44424* hilli::!:: Should interaction effects be noticed, try II, - -)14%.: INSULATING ''ijfi 5; 1- : : :__5;5;.j.±17:41:' soldering a wire to each iron core and LAYER takingitto earthThis will sometimes Fig. 1-Diagram of Open -core Transformer. Fig. 2.-Diagra n of Clcsed-core Transformer. work a cure; but if it fails, the best thing to doistoencloLe each low -frequency magnificationisaltogethertobecon-can test the set for interaction effects bytransformer in an iron case, which will demned. On the contrary, it has its ownusing flexible leads, say a yard in length,confine the greater part ofits magnetic uses,performingtasksthatthehigh -instead of the short brass strips, to connectfield to its own immediate neighbourhood. frequency system cannot accomplish, andtwo low -frequency panels.Before switch- it is usually desirable to have certainly oneing on move the panels away from eachWhat the Transformer Does stageof audio -frequencyamplificationother to the fullest extent of the wires. The chief dutyofthelow -frequency available in the multi -valve set.ThanksNow turn on thecurrent, tune into atransformer is to act as a "booster " to the to the unit system it can always he thrown impulses supplied by the plate of the pre- out of action in a moment when it is not cedingvalve. Whentwocoilsare wanted. PRIMARY op coupled, breaks or changes in the current IP CI"-, flowing in the primary will cause spurts Note -magnifiers in Cascade TRANSFORMER SECONDARY of current to occur in the secondary.The Itis, of course, possible to use two or OSI IS 0 secondary terminals of a transformer there- more note -magnifiers in cascade, but Unless ToPHONESof foredeliverelectricalimpulseswhich thesetis requiredto operatealoud PRIMARY OF NEXT VALVE correspond exactly with those that enter speaker giving a volume of sound sufficient those of the primary.But if the windings tofill a largehall,itisbetter notto of the secondary are more numerous than employ more than one.High -frequency those of the primary the current will be so transformers can beplaced quiteclose altered by it that its voltage is increased. together without undesirable results, but We do not obtain more current, for the with the iron -core instruments needed for step-in in voltage is accompanied by a dealing with audio -frequency impulses the corresponding loss in amperage; but as the case is different.Unless they are widely 0 operation of the amplifying valve depends separated a certain amount of interaction LT* takes place, which gives rise to distortion upon potential changes in the grid circuit, and sometimes to an orgy of howls, in Fig. 3.-WiringDiagram of Low -frequency this is exactly what we require.The in- comparison with which the mightiest vocal Panel. crease of potential is almost in proportion efforts of a pair of warring tomcats are to the number of turns in the primary and strong signal and listen carefully.Slide secondary coils respectively.Hence, if the mere dulcet flutings. the outlying panel gradually towards thelatter contains five times as many turns as The low -frequency unit used with the setother, remaining at the same time on thethe former, the potential will be raised by under description is shown in Figs. S andlook out for any change in the quality ofabout five times.This ratio of five to one 9 in the article on page 614, which givethe signals.If they become blurred orhas been found to give the most satisfac- the details of its economy both above andaccompanied by outside noises as the dis- below the panel.It will be noticed that tory results for the low -frequency trans- the transformerisso arranged thatits WINDINGS windings are at right angles to the long 05 side of the panel.If the reader contem-

plates the employment of more than one E13.1%/H, such unit he is advised to mount. the trans- IP former with its coils parallel to the ebonite 1.0. ,././....,9356, LT- strip, otherwise itseffects upon its next- LT. door neighbour may be so serious as to impair the working of the set. Fig. 4.-Leads of Low - fiwta570 frequency Transformer. Fig. 5.-Diagram showing Control of Three Low - Interaction Effects frequency Panels with One Rheostat. There are several ways of minimisingtance between the panels is decreased, thenformers used in the receiving set, providing theinteractioneffectsoflow -frequencyinteraction is present.It is best to makealways that the primary is large enough to transformers mounte Iin cascade.Nonethe test also with. a telephonic transmis-give the necessary factor of impedance. DECEMBER 16, 1922 645 111 0 FAT WIXO1055 The function of the iron core is to act as ontheother. The inputand outputfilament rheostat for each low -frequency a path for the electro-magnetic lines ofterminals can, however, be readily foundunit, for since the valves are doing the force set up by currents flowing throughif you remember that the input lead willsame work they willrequirethe same the windings.In order to compel as manyalways come fromapointnearertheamount of current.Fig. 5 shows how one of them as possible to do useful work thecentre of the coils than the output lead.resistance may be made to control all of coreis of what is known as the closedFig. '4 makes this quite plain. In connect-them. Ifasinglerheostatisusedit type ;that is,instead of being simply aing up the wires join the terminal leadingmust he capable of carrying 2% amperes. straight bundle of iron wires it is shapedfrom the plateof the preceding valve to In the next article we shall describe the into what may be termed a "square 8,"o P, and r p to H.T -F.r S is joined to theconstruction of the end panel, on which both primary and secondary coils beinggrid, and o sto L.T-. H the connec-are mounted both loud speaker and tele- wound on the middle bar.Figs.i and 2tions are not made as shown the trans-phones,aswitchenabling either to be illustrate the effects of this arrangement. former will not work properly. thrown in or out of operation. We shall Fig.r shows an imaginary section of an Valves of the type used on the high- also discuss some possible refinements, and open -cored transformer.All of the linesfrequency panels will be found to answersee how to make profitable use of the fifth of force from the primary move along theadmirably for note magnification.Thereterminal, which so far has been allowed to straight core, but many escape at the endsis no need, by the way, to have a separateremain idle. R. W. HALLOWS. without ever having passed through the secondary.In Fig. 2 the working of the Ei530,JCg3CE_ closed -core type is seen diagrammatically. 11 The iron offers far less opposition to the [EI passage of the lines of force than does air; hence all but a very few of them move FormingaWireless Association roundthecore,passing ontheir way through to windings of the primary, and doing useful work. amateur wireless society may consiststruct your own set from home-madeor The rectifying valve does not functionANTof three or more members, and if thebought parts. quite perfectly, for it allows a number ofthree are respectively the chairman, the The matter of forming an association is high -frequency pulsations to pass throughsecretary and the treasurer, with power tonot quite so easyif a large membership it,and these go on tothe transformeradd to their number, you have an idealis probable. You have now a more diverse mingledwithlow -frequencyimpulses. nucleus round which to gather andtostandard of attainment and the capacity to Their presence in audio -frequency circuitswork. Howeversmallyourtown,it attempt greater things. is undesirable, and some means of gettingsurely will contain three people who are rid of them must be found.This is done To meet such a case the formation ofa interestedinwirelessmatters. A Postspecial committeeis advised whose sole by providing a capacity in the primary ofOffice permit is not necessary before you the transformer which will act as a by-pass function is to find out the requirements of can hold a meeting, but you will find thatindividual members and recommend to the for them.It usually takes the form offew meetings will have taken place beforechairman and the secretary that the dis- afixedcondenserof.00r mfd.shunted most of the members are in possession ofcussions and instructions should followa across the primary terminals, the necessary permit to receive wirelesscourse best designed to meet the individual transformers, such as the type shown insignals. need.Everything else which you may do Fig.r, are so wound that their own self - The authorities are invariably well dis-must be subservient to capacity is sufficient for the purpose.The this.Where the posed toward the bona -fide wirelessex- plan outlined above has been adopted low -frequencypanel,whenmadeup, it perimenter, and if you have given proofhas worked admirably.Meetings, how- should be tested with and without such aby banding together intoasociety,theever large or small, must be conducted on condenser in order to see which gives the PostOffice can hardly go hack onits parliamentary lines. best working. The speakers must word and refuse to listen to the appeal foraddressthechairman,whomustbe Low -frequency condensers range in priceexperimentallicenceswhentheyareselected on account of his suitability for from 14s. to 2. A small type used duringbacked up by the signature of your electedthe post. setscan be the war in army receiving secretary on club notepaper and concurred The secretary also will either makeor bought at the lover figure mentioned. I in by the other members of the commitee.mar the society, but he has to be more or cannot claim to have tried them, but some In order tojustify the good opinionlessof an opportunist, and though he who have done so give good reports ofwhich the authorities have, the writer sug-cannot be all things to all men, he has to them.In this type the core is providedgests a definite course of elementary studytrimhiscoursebythewishesofthe with a lead ready fixed for earthing pur-beginning with an easily -made tuning in-majority. poses.Remember that the success of yourductance, passing on to a crystal detector, An expert visitor who can appreciate audio -frequency panel depends verythe telephones and the aerial, and by theyour needs and meet them in a talk or largely on the design and finishof thetime you have studied these theoretically,lecture is a very desirable person, but one transformer.A badly made instrumentby the aid of the cheap and good literaturewho cannot get down to your levelis a can never do good work; it pays thereforenow on the market, you will be quitedrawback rather than a help.He will talk to buy a kind that is guaranteed by thereadyand capableofputting yourso over your heads and you will go away makerstohave been thoroughly testedacquired knowledge to the test of experi-confused rather than edified. before leaving the. factory. ment and, as before said,will probably Don't stint yourself in stationery.You Fig. 3 gives a wiring diagram of thehave received the official sanction to do so. willoftenbe judged by yourletters. panel.Initthe transformerisshown Let it be clearly understood that if youPublicity is good.It keeps you up to the mounted as seen in the photograph; dopurchase a broadcasting licenceat yourmark and brings in new blood, without not forget to make the necessary change inPost Office you will not be permitted towhich no society can progress. its position if you intend to have two orperform any experiments other than turn- Read the'report-s- of the doings of other more note -magnifiers. ingthevarious knobs on your dearly -societies and tryatleastto equal their There is one point of importance in thebought apparatus, and hoping that some- doings. wiring up of the transformer.Some ofthing will happen as a consequence.The Nearly all newly -joined members will them have the input and output terminalsonly thing you will be allowed to do onhe most diffident as to their worthiness of of primary and secondary marked r P, o P,your own will betheerection of yourbelonging to your society.Do your best S, and o S, but others are merely letteredaerial.If, on the other hand, you obtainto put them at their ease, and thaw them "primary " on one side and "secondary "an experimentallicence,you cancon- outoftheirreserve. SIGMA. mottur Wireless 646 DECEMBER16, 1922

CtThflir=g212T&:ItgILI-4:LTTP:5771,175-5-kri-q:g3Lg,a=7.- 101 The Bending of Waves An Entertaining Article by Mr, Robert G. Lunnon, M.A., B.Sc., on an Abstruse Question 1I21 tJ

HOW can wireless waves bend half -waysider the behaviour of those ether waves Is this phenomenon of diffraction suffi- round the world ?The questioniswhich are visible as light..They can becient to account for the fact that with a a very puzzling one, and the scientist isreflected and refractedeasily ;do theywave -length of ten miles we can com- not yet certainofitscomplete answer,show diffraction?They certainly do notmunicate with the Antipodes ?The answer although his knowledge of other kinds ofbend far round the earth, for a ship's sailsis that the waves would indeed bend so waves goes some way towardsit.Con-soon disappear on the horizon.If lightfar by diffraction, but they would be far sider, for example, how sound waves bend.rays enter by a keyhole they do not appearweaker on arrival than is actually the case. We all know that sound can pass roundto spread out in the least.Sound waves, corners, and there are three ways in whichhowever, are very much longer than lightA Problem Solved it does so.If a band is playing in frontwaves, being commonly 3ft.or 4ft.in It was in 1918 that G. N. Watson solved of a houseit can be heard at the back,length, whereas the longest waves of lightthe problem which had baffled many lead- although notallthenotesare equallyare less than one thirty -thousandth parting mathematicians, and calculated hoW audible ; the low notes travel best, and theof an inch.By suitable methods the bend-far the wave should bend round the earth. high-pitched instruments may scarcely being of light can be made clear.If a smallActual measurements of the strengths of heard.Again, in a whispering gallerypinhole be placed in front of a strongsignals over very long distances were made even a faint sound can be carried roundlight, and a threepenny -piece be hung atby the Radio Department oftheU.S. a large part of a circular gallery.Andabout six yards distance, then at the veryNavy in the yearS before the war, and one thirdly,the sounds from some powerfulcentre of its shadow, at the same distanceof Austin's actual measurements of recep- source, such as gunfire or an explosion,on the other side, a tiny bright spot maytionat 6,000 miles was seven thousand are sometimes heardatgreatdistancesbe seen and photographed.The light hastimes greater than Watson's formula could when they have not been audible at all atnot come through the centre of the coin explain.So the theory, long thought to nearer places; they have travelled up intoit has been able to bend through the verybe the only possible one, has failed, and the air and have been bent down again insmall angle, less than twenty minutes (yi°)physicists'thoughtshavebeenseeking An arc.Isit by methods similar to oneof arc, involved in passing round the edge.other channels.The most fruitful result or allof thesethatelectric waves areSimilarly if the edge of a knife blade behas been due toa suggestion made, by curved? held in a suitable beam of light, it is pos-Oliver Heaviside many years ago, based on sibleto see with a microscope that thethe whispering gallery analogy.If the Three Effects clear edge of the shadow seen with thewaves do not spread out freely upwards These three effects are classified as lasesnaked eye does not exist, but some lightfrom the generating station, but are re- of diffraction, reflection and refraction re-bends round the edge, the shadow onlyflected downwards and outwards by some spectively.In the last case the air is ofgradually deepening into complete dark-upper layer of the atmosphere, then they different densities and temperatures at dif-ness. will travel very much farther round the ferent places in the path of the sound, so earth.Such an upper layer would make that some parts of the wave travel moreCharacteristics of Long and Short Wavesthe whole earth one vast whispering 'gal- quickly than others, and its pathis no The shortest waves bend least.An aver-lery for electric waves by preventing the more a straight line than the path of aage X-ray isa wave 5,000 tubes shortergreat waste of wave energy sent out into squad of soldiers would be if the men onthan red light, and until 1912it had notthe interstellar spaces.The theory would one side marched more quickly than thosebeen discovered that X-rays could curve atbe admirable if we could understand how on the other.The whispering gallery isall, so that it was doubted whether theysuch a "Heaviside layer," with a definite acaseofreflection-thefeeblesoundwere really waves.But the electric wavesreflectinginnersurface,couldbepro- waves from a whisper are 'not allowed tothat Hertz discovered in 1888 were severalduced. waste their energy by spreading outinfeet long, and it was not surprising there- all directions, but by repeated reflectionsfore to find that such waves could divergeA Reflecting Layer they are kept going for a long distancewidely from a straight line path.Now we Now electric waves are only reflected round the narrow gallery.The method ofuse waves far longer than any Hertz couldfrom conductors of electricity-evenfor diffraction is harder to understand.Theproduce, and they can very easily curvethe short light waves metals are the best sound waves from the band travel roundround ordinary obstacles.' An experimentreflectors. Airisa non-conductor-if it the house because every part of each ad-of CampbellSwinton'sisone of manywere otherwise wireless could never exist vancing wave sends on the sound as, ifitthat show thisclearly.He enclosed a-but it can be made into a conductor; were itself a new centre for the wave.wireless receiving apparatus inalargethatis,it can be ionised by passing X- That" isto say, it sends on the wave in allcovered tin with one side cut out.Whenrays, or ultra -violet light, or strong elec- directions, and not only forward initsthis open side was pointed directly awaytriccharges throughit,and in certain original direction.In the same way iffrom the sending apparatus the signalsother ways.Professor Fleming therefore a noise comes into a room through a key-were received perfectly clearly, so that thesuggests that this invisible reflecting layer holeitspreads out inside the room inwaves had been able to bend right back issimply the boundary of a great, per- alldirectionstovariousdegrees-mostround theedges. Even withtheside manentlyionisedportionofthe atmo- strongly,of course,inthelineofthealmost closed again, and only a narrowsphere.It may be about 5o miles above hole. slitleft, the waves could penetrate.Sirthe surface of the earth, where the atmo- Oliver Lodge has found thatif a smallsphere is chiefly hydrogen, and the ionisa- The Behaviour of Ether Waves round hole is left instead of a slit the sig-tion is due to strongly electrified particles Bitt sound waves are entirely different innals received inside are very much weaker,of dust sent into our atmosphere by the characterfromeleetromagnetic waves-and healsofoundthatthey may besun.It is known that dust particles of a they are waves in air, not in ether-andstrengthened by holding a short piece ofcertain size will be repelled by the pres- these analogies may be misleading.Con-wire through the hole. sure of sunlight, and Fleming calculates DECEMBER16.1922 647 Ottullutr Wire6.5 that this dust will be unable to fall farther ff]t:Irti33ffiff3ff3tcgi:tPt]rg31:PrtPcgIttPcrInriP0 towards the earth because of the viscositycattiJff3EL._:_',--,:_,------cfP5L-,52-5. 16 [6 Ui of the gas around it.Some particles will v be positively charged with electricity and RADIOGRAMS Yi [6 some negatively,buttheydonotre- Li ta combine for two reasons :they are different 16 in size, which makes them fall to different[13E,_ITLT-::_ti-c_i:Pit]ric-L-:-..LT-rsir-.1,7-L.,:i:JirsPagzEgiff2ff]iti3i:g:tcl[c§:ltfi3t±PrEl levels, and they are drawn inopposite CHRISTMAS greetings will be sent onto which it will be put will be to send out directions by the earth's magnetism.And Christmas -eve by wireless to the smallreports of shoals of fish to fishing boats. so a great fixed wall is hung above the

colony of workers at King's Bay, Spitz- earth, and continually renewed by vast it bergen.Spitzbergen is1,5oo miles from Dr. Lee de Forest will be able for the streams of two kinds of dust thrown offLondon. from the sun. first time to manufacture his own inven- It is a daring suggestion, but its deductions seem to be perfectly in tion, as the Fleming patent, which was accord with facts, for a calculation of the A Lincoln hairdresser has installed aowned by the Marconi Telegraph Co., strength of signal to be expected has beenreceiver in his shop, and customers are in-expired in the United States on Nov. 7. The made and agrees with experiments.It hasvited to be "shaved by wireless." some support, too, from the meteorologists,Daily Telegraph asks, "Who would choose A particularly neat receiver has been for they can only explain phenomena like tosit beneath the barber's steel at theproduced by using plate glass panels. auroraborealisbymeansofsimilarmoment when theartist heard that the theories. horse which carriedhis money orthe There is, however, a difference in thecandidate of his affections had been the Mr. F. G. Kellaway took over his new amount of curvature which electric waveslast of the field ? " duties as director of Marconi's Telegraph can accomplish in daytime and in night- Co. on Dec. 4. time.This is readily understood as the An Australian amateur has succeeded in effect of the shortest invisible waves oftransmitting speech, using only 3.2 watts A number of trained canaries supplied sunlight,for in the daytime these rays inpower,fromStrathfieldtoSydney,the entertainment of a programme broad- ionise the atmosphere for some miles be-Melbourne, a distance of 42o miles. cast from San Francisco recently. neath the Heavisidelayer, and so the . surface of the layer becomes less clear and . sharp for reflecting purposes.Daylight Captain W. G. R. Hinchliffe, pilot of There has been some difficulty in finding hangs curtains round the wallsofthethe London to Amsterdam air mail, was ina suitable site for the Glasgow broadcast- world's vast whispering gallery, and byconstantcommunicationwithCroydoning station, but when it is opened-which dulling the reflections makes the signalsaerodrome whilst circling over Amsterdam.may possibly be before the end of the year less audible.Besides this, the upper partsThis is a new record in wireless telephony.,-it is thought that there will be a re-

of the waves must travel more quickly in ix arrangement of the wave -lengths in use to this partly ionised air, and so the waves Controlofwirelesstelephony by theallow of the Scottish transmissions being come down again to earth more quicklyProvincial Governments is recommendedgiven somewhere between the mean time before they have travelled so far as theyby the Canadian telephone departments. limits of 36o metres at Marconi House and At sunset and sunrise, 420 at Birmingham. The Glasgow station, can do at night. by the way, will cater for the whole of too, and at times of heavy thunderstorm, Australia is to have a radio concert ser- therapidchangesintheatmospheric Scotland at first, as well as the North of vice,inaddition to an up-to-date com-Ireland.It will be run on the same lines ionisation produce other strange variationsmercial wireless telegraph service. in the paths of the waves.They become as the three in service in England.

locally distorted, and not only is the dis- tances of their travel irregular, but they Itis probable that wireless telegraphy There is quite a probability that once may be changed in direction.This side-stations will be erected at Julianchaab,broadcasting gets into its stride the power wise bending of the wave isa seriousGodthaab, Godhavn, and Angmagssalik,all round will be raised to the neighbour- hindrance when the wave is being used forin Greenland. hood of 3 kw. directionfinding, and the best modern im

apparatus for these purposes is unreliable An electric power company in Japan has at times. asked for permission to link up its various In theUnitedStates broadcastingis Wireless waves curve round the earth,generating stations by wireless. enjoyed every night by between half and therefore, under the influence of all the three-quarters of a million of people.It threetendencieswhichwavespossess. isfully believed that similar huge audi- They arediffracted,theirdiffractionis It is hoped that the broadcasting stationsenceswillbe obtainedinthiscountry very much helped by reflection in the greatat Newcastle and Cardiff will be in opera-within a very short period, in which case whispering gallery of the atmosphere, andtion by the end of the year. theBroadcastingCompanygivesthe lastly, their paths suffer further distortion, a is assurance that it will be able to get the andthatharmfully,fromrefraction. A broadcasting company is being formedvery finest artistes, teachers, and preachers These are the outlines of the answer to ourin Sweden. -in fact, everyone who has a worthy mes- sage to give. question. R. G. L. a

is Tenthousandexperimentallicences " Using a Gramophone as an Orches-have been issued during thelastseven Further proof thatScottishamateurs tra " is one of the articles in this week'smonths, which now make -a total of 18,000. can bear comparison with their English issue of " Work " (3d.).Other articles in- brethren is given by the reports of two clude :" Making Toys from Waste Tins," enthusiasts north of the border as to hear- " A Simple Magnetic Fishpond," " Two Letter messages can now besentating telephony in which the voices had an Clothes -airing Devices," " Easy but Effec-week -ends to America via Marconi for 3d.undoubtedly American twang. The source tive Conjuring," " The. Pin -wheel Clockper word. of the transmissions was not ascertained, Escapement," "AmateurWirelessat II but oneoftheexperimenters was of Christmas,"" HowtoGrindGlass," A new wireless station is being erectedopinion that what he heard was someone " Decorations in Strip Tinplate." at Gothenburg, and one of the many usesspeaking to a passenger on a liner. entatturWireless 648 649 Ontabutrwttass

-7:L5LT fft-7-'c:!-,T,-..7t5':17,--r-L1--rLtSFrr:-T5ffltf- .75 - 77T7:7!TL7:71T7--:717 1- 7.7--7 -77-717 7'7 7.±777.'971157,5 -77' -F7 -L-7 57:1775:_fP'2t7Cf]l5CTOItI15127015LPIDE:1'

AS anaturalsequenceto the 16' II amazing progress made in the science of wireless within the last WIRELESS AS A PROFESSION few years, many people are con- ra sidering the suitability of wireless The Manipulative Branch adverse economic conditions, that the exact establishedPostOfficetelegraphists,so EP] lI as a means of livelihood, and we demands the services of specially -trained are constantly being asked for in- Thisisthebranchwhichwillun- scales cannot be stated.However, it will operators.It will therefore be seen that that anyone wishing to enter this service formation as to how the profession doubtedly appeal more strongly. tothe not be far out to put the limits between a 41the prospects of a sea -going operator can- must firstobtain a position id the Post aspirationsofyoungpeople.Itisto minimum of ,42 and a maximum of Z5 per not be considered alluring, especially when OfficeTelegraPh Service. Once there, 5' may be entered and what prospects 41 it offers. thisblanchthat the wirelessoperator week. Rationsaboardare,ofcourse, it is remembered that the position entails several years of manipulation work will This article, written by follow, during which time he will become aPost explains belongs, whose position and the means of supplied at the expense of the shipping many years at sea with its dull monotony Officeoperator, obtaining it will now be analysed. companies. thoroughly acquainted with the different exactly the present-day position, and ;Randthelackof homely comforts and Therearetwodistinctbranchesof ' With regard to promotion the sea -going associations.This is a point upon which systems of telegraphy, and finally emerge it will be seen that the immediate operators-each of which have their own operator has small prospects.So much so, too much emphasiscannot beplaced, a first-class operator.It is at this stage of prospects are none too bright;in particularsphereofactivity,and who indeed, that his job can undoubtedly be because so many people have learnt this his career that he may secure a transfer to fact,the- authorpracticallygives belong to two separate and independent classed as one of the "blind -alley " type. truth too late. the wireless branch of the service, in which the same advice as did Mr. Punch services. The company to which he belongs has no'" case a new phase of life will be entered to those about to marry-" Don't." Firstofallthereis thesea -going suitable positions for him ashore.In the The Land -station Operator upon.His new work will probably take operator, the majority of whom constitute case of the Marconi Company a limited The lot of this operator will now be con- him toone of the lonely spots of the Lifeboat Fitted with Wireless. 41 thestaffofthe MarconiInter- country where a station is situated, nationalMarineCommunication but he will hive plenty to occupy [Of AGREAT many people, fascinated by -72 less service beyond this point need not be Company; and secondly, there is his mind for the first two years. la the wonders of wireless telegraphy p .1" 4) pursued,enoughhavingbeensaidto 18 andtelephony, seriouslycontemplate the land -station operator, who, in During this period of time he will showthedifferencebetweenthetwo taking up the science as a profession and most cases,isa member ofthe becompelledtostudyhardin classes of operators. Post Office wireless service. order to pass the required depart- . a means of livelihood.The' greatdiffi- It is hardly necessary to point out that If, mental examinationsinFrench, 15 culty they experience, however, is the lack neither class, can be accused of making of useful information which will give them The Sea -going Operator German, andtechnicalwireless fortunes out of wireless.The only people a true perspective of things and help them The Marconi operator is the in- telegraphy.Failure to accomplish who are able to do that are those whose this will probably result in his re - to gauge the possibilities of success. dividual Avith whom we are most interestin thescience does not extend tit transfer to the telegraph service. Generally speaking,theprofession-is familiar.His sphere of dutyis beyond the number at shares they hold in 4i dividedintotwoseparate and distinct aboard ship-a fact which forces Success, however, means hisac- the various wireless companies: branches-the engineering branch and the him to lead .a seafaring life.His ceptance on the permanent wire- The businessoftheoperatoristhe lessstaffasanoperator,after' manipulativeoradministrativebranch, position is attained in one otwo serious one of dealing with the messages of kt) each of which has its own particular class ways.He may either pay a fee which he will be liable for duty at the public and of carrying out the provi- tO1 of work to perform.The former is respon- and receive his training at one of any of thePostOfficestations sions of international wireless laws, with- L -r) sible for the production of apparatus and the many wireless schools estab- within the British Isles(Ireland outwhichtheetherwouldbeina excepted). tv 115 the erection of wireless stations, but it is lished throughout the country, or perpetual state of pandemonium and chaos. The 'pay oftheseoperators [tt the work of the latter branch to operate he may be chosen by the Marconi Furthermore, he must be very watchful tti them and to make the necessary arrange- Company to attend their school of ranges from a minimum of 38s. to for signals of distress and ready atall ments for handling wireless traffic. instruction,forwhich,itisbe- a maximum of 75s. per week, plus times -to carry out the "safety at sea " 15 lieved,no feesarerequired. 10111MMIMINIMMINV theCivilServicecost -of -living regulations. 1,',111 The Engineering Branch Whichever be the plan chosen the bonus,whichisrapidlyfalling. Such men havelittletimeforthe So far as this branch is concerned the object is the same, namely, that of The working. week is one of forty- pleasures of wireie-ss telephony, -their duty only position of importance is that of the qualifying forthePostmaster - five hours spread over six days; compelling- them to listen for hours at a 'a radio engineer.He is the man who has General's certificate of proficiency the time beingdividedbetween time to the ceaseless buzz of dot and dash. made the science of wireless and electrical in. wireless telegraphy.. This cer- day and night in the ratio of about S. engineeringalifestudy.His workis tificate must be held by everyone three to one. [41 primarily that of designing apparatus and desirousoftakingupwireless The prospects of promotion are stations and for seeing that his specifica-.duties afloat, and it usually takes not very bright in normal times, as A List of Addresses tions are properly executed.The actual a person of average intelligence at itis usually a.case of waiting for useful to any candidate for tpi work of manufacturing the many corn- least a year of conscientious work deadmen'sshoes. Therank theWirelessProfession. ponent parts of the apparatus is under- isan and study under the tuition of ex - above that of an operator Amalgamated Wireless (Australasia),. I.td., taken by various firms who specialise in perience.d teachers in which to gain Overseer or. supervising officer, and " Wireless House," Clarence Street,Sydney.; i;) these matters.The radio engineer, there- it.Having secured it and obtained - whena vacancy for such occurs New South Wales. 4.A 15- fore,isinaclass ofhis own, whose a position with the company, the the senior operator in the service Marconi International Marine Communica- numbers are verysmall. His training young operator is soon detailed for selected for promotion, provid- tion Co., I.td., Marconi House, Strand, lon- Sketch of Interior of Wireless Cabin of a Ship fitted with Marconi Insf.urr.ents. is W.C.2. ifh necessitates the possession of brains and a sea duties.Obviously the choice of ing his official record is clean and Marconi's WirelessTelegraphCo.,Ltd., goodly supply of cash, and. in most cases a ship cannot be given him, but it he has passed the necessary quali- _Marconi House, Strand, London, W.C.2. Vi he is found to be a man who has had a isgenerally the case for him to spend number of inspectorships are available to sidered.He is the man who performs his fying technical examination.Men of this RadioCommunicationCo.,I.td.,34/35, universityeducation.The fieldof em- the first years of his career aboard ships rank take duty as officers in charge of Norfolk Street, London, W.C.2. 15 their operators, but the number of appoint- duty at one or other of the Post Office R.M.Radio,Ltd!,5,Regent'sSquare, 18 ployment for such a man is not very large, of the cargo type.Naturally, positions ments are so small compared to the large land stations, through which the sea -going stations, or perform Government ship in - 4:1 Gray's Inn Road, W.C.I. 'a being practically confined to the service aboardthebestships arereserved number of operators, that the chances of operator sends and receives his messages. spection duties at one or other of the large Chinese National Wireless Telegraph Co., 5, 'a of large firms of wireless manufacturers.. for,theseniorandmoreexperienced The service. to, which he belongs isthe ports.They may also be called upon to Peh Ch'a Ta Fu Ssu, Peking. securing one are infinitely small.More- COI CompaniaMarconide. Telegraphia. Sin More than this need -not be said with operators. over, this particular class of operator has Post Office Wireless Service, the supreme examine candidates for the P.M.G.'s cer- Vi Hilos del Rio de I.a Plata, Calle l.avalla, 50, fa regard to this branch, where it is not diffi- The next question to be considered is the little hope of serving at one of the corn- head of which is the Inspcctor of Wireless tificates, or to work as clerical officers on Buenos Aires, Argentina. cult to see that the prospects of obtaining interesting one of pay.So many adjust- pany's high -power stations, because theATelegraphy.Recruits for this service are the headquarters staff at the G.P.O. Companhia Radiotelephica Brasileira,io7, wtill 15 lucrative employnient are 'very remote. ments, have recently been made, dup to nature of the work they do at such plaCes exclusivelydrawnTromtheranksof The constitution of the Post Office wire- Rua to de Marco, Rio de Janeiro. Yi kit Offiduziegiduc4rgs3iTrrect7Iffic4f2TrTzT. ffitOIDE_Fi-fficT55E.TOfficrElrglfflcf7,0th--100dP-TOfflOgirli3ttliiTdPrffiffiofflil entatturWireless 648 649 Ontabutrwttass

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AS anaturalsequenceto the 16' II amazing progress made in the science of wireless within the last WIRELESS AS A PROFESSION few years, many people are con- ra sidering the suitability of wireless The Manipulative Branch adverse economic conditions, that the exact establishedPostOfficetelegraphists,so EP] lI as a means of livelihood, and we demands the services of specially -trained are constantly being asked for in- Thisisthebranchwhichwillun- scales cannot be stated.However, it will operators.It will therefore be seen that that anyone wishing to enter this service formation as to how the profession doubtedly appeal more strongly. tothe not be far out to put the limits between a 41the prospects of a sea -going operator can- must firstobtain a position id the Post aspirationsofyoungpeople.Itisto minimum of ,42 and a maximum of Z5 per not be considered alluring, especially when OfficeTelegraPh Service. Once there, 5' may be entered and what prospects 41 it offers. thisblanchthat the wirelessoperator week. Rationsaboardare,ofcourse, it is remembered that the position entails several years of manipulation work will This article, written by follow, during which time he will become aPost explains belongs, whose position and the means of supplied at the expense of the shipping many years at sea with its dull monotony Officeoperator, obtaining it will now be analysed. companies. thoroughly acquainted with the different exactly the present-day position, and ;Randthelackof homely comforts and Therearetwodistinctbranchesof ' With regard to promotion the sea -going associations.This is a point upon which systems of telegraphy, and finally emerge it will be seen that the immediate operators-each of which have their own operator has small prospects.So much so, too much emphasiscannot beplaced, a first-class operator.It is at this stage of prospects are none too bright;in particularsphereofactivity,and who indeed, that his job can undoubtedly be because so many people have learnt this his career that he may secure a transfer to fact,the- authorpracticallygives belong to two separate and independent classed as one of the "blind -alley " type. truth too late. the wireless branch of the service, in which the same advice as did Mr. Punch services. The company to which he belongs has no'" case a new phase of life will be entered to those about to marry-" Don't." Firstofallthereis thesea -going suitable positions for him ashore.In the The Land -station Operator upon.His new work will probably take operator, the majority of whom constitute case of the Marconi Company a limited The lot of this operator will now be con- him toone of the lonely spots of the Lifeboat Fitted with Wireless. 41 thestaffofthe MarconiInter- country where a station is situated, nationalMarineCommunication but he will hive plenty to occupy [Of AGREAT many people, fascinated by -72 less service beyond this point need not be Company; and secondly, there is his mind for the first two years. la the wonders of wireless telegraphy p .1" 4) pursued,enoughhavingbeensaidto 18 andtelephony, seriouslycontemplate the land -station operator, who, in During this period of time he will showthedifferencebetweenthetwo taking up the science as a profession and most cases,isa member ofthe becompelledtostudyhardin classes of operators. Post Office wireless service. order to pass the required depart- . a means of livelihood.The' greatdiffi- It is hardly necessary to point out that If, mental examinationsinFrench, 15 culty they experience, however, is the lack neither class, can be accused of making of useful information which will give them The Sea -going Operator German, andtechnicalwireless fortunes out of wireless.The only people a true perspective of things and help them The Marconi operator is the in- telegraphy.Failure to accomplish who are able to do that are those whose this will probably result in his re - to gauge the possibilities of success. dividual Avith whom we are most interestin thescience does not extend tit transfer to the telegraph service. Generally speaking,theprofession-is familiar.His sphere of dutyis beyond the number at shares they hold in 4i dividedintotwoseparate and distinct aboard ship-a fact which forces Success, however, means hisac- the various wireless companies: branches-the engineering branch and the him to lead .a seafaring life.His ceptance on the permanent wire- The businessoftheoperatoristhe lessstaffasanoperator,after' manipulativeoradministrativebranch, position is attained in one otwo serious one of dealing with the messages of kt) each of which has its own particular class ways.He may either pay a fee which he will be liable for duty at the public and of carrying out the provi- tO1 of work to perform.The former is respon- and receive his training at one of any of thePostOfficestations sions of international wireless laws, with- L -r) sible for the production of apparatus and the many wireless schools estab- within the British Isles(Ireland outwhichtheetherwouldbeina excepted). tv 115 the erection of wireless stations, but it is lished throughout the country, or perpetual state of pandemonium and chaos. The 'pay oftheseoperators [tt the work of the latter branch to operate he may be chosen by the Marconi Furthermore, he must be very watchful tti them and to make the necessary arrange- Company to attend their school of ranges from a minimum of 38s. to for signals of distress and ready atall ments for handling wireless traffic. instruction,forwhich,itisbe- a maximum of 75s. per week, plus times -to carry out the "safety at sea " 15 lieved,no feesarerequired. 10111MMIMINIMMINV theCivilServicecost -of -living regulations. 1,',111 The Engineering Branch Whichever be the plan chosen the bonus,whichisrapidlyfalling. Such men havelittletimeforthe So far as this branch is concerned the object is the same, namely, that of The working. week is one of forty- pleasures of wireie-ss telephony, -their duty only position of importance is that of the qualifying forthePostmaster - five hours spread over six days; compelling- them to listen for hours at a 'a radio engineer.He is the man who has General's certificate of proficiency the time beingdividedbetween time to the ceaseless buzz of dot and dash. made the science of wireless and electrical in. wireless telegraphy.. This cer- day and night in the ratio of about S. engineeringalifestudy.His workis tificate must be held by everyone three to one. [41 primarily that of designing apparatus and desirousoftakingupwireless The prospects of promotion are stations and for seeing that his specifica-.duties afloat, and it usually takes not very bright in normal times, as A List of Addresses tions are properly executed.The actual a person of average intelligence at itis usually a.case of waiting for useful to any candidate for tpi work of manufacturing the many corn- least a year of conscientious work deadmen'sshoes. Therank theWirelessProfession. ponent parts of the apparatus is under- isan and study under the tuition of ex - above that of an operator Amalgamated Wireless (Australasia),. I.td., taken by various firms who specialise in perience.d teachers in which to gain Overseer or. supervising officer, and " Wireless House," Clarence Street,Sydney.; i;) these matters.The radio engineer, there- it.Having secured it and obtained - whena vacancy for such occurs New South Wales. 4.A 15- fore,isinaclass ofhis own, whose a position with the company, the the senior operator in the service Marconi International Marine Communica- numbers are verysmall. His training young operator is soon detailed for selected for promotion, provid- tion Co., I.td., Marconi House, Strand, lon- Sketch of Interior of Wireless Cabin of a Ship fitted with Marconi Insf.urr.ents. is W.C.2. ifh necessitates the possession of brains and a sea duties.Obviously the choice of ing his official record is clean and Marconi's WirelessTelegraphCo.,Ltd., goodly supply of cash, and. in most cases a ship cannot be given him, but it he has passed the necessary quali- _Marconi House, Strand, London, W.C.2. Vi he is found to be a man who has had a isgenerally the case for him to spend number of inspectorships are available to sidered.He is the man who performs his fying technical examination.Men of this RadioCommunicationCo.,I.td.,34/35, universityeducation.The fieldof em- the first years of his career aboard ships rank take duty as officers in charge of Norfolk Street, London, W.C.2. 15 their operators, but the number of appoint- duty at one or other of the Post Office R.M.Radio,Ltd!,5,Regent'sSquare, 18 ployment for such a man is not very large, of the cargo type.Naturally, positions ments are so small compared to the large land stations, through which the sea -going stations, or perform Government ship in - 4:1 Gray's Inn Road, W.C.I. 'a being practically confined to the service aboardthebestships arereserved number of operators, that the chances of operator sends and receives his messages. spection duties at one or other of the large Chinese National Wireless Telegraph Co., 5, 'a of large firms of wireless manufacturers.. for,theseniorandmoreexperienced The service. to, which he belongs isthe ports.They may also be called upon to Peh Ch'a Ta Fu Ssu, Peking. securing one are infinitely small.More- COI CompaniaMarconide. Telegraphia. Sin More than this need -not be said with operators. over, this particular class of operator has Post Office Wireless Service, the supreme examine candidates for the P.M.G.'s cer- Vi Hilos del Rio de I.a Plata, Calle l.avalla, 50, fa regard to this branch, where it is not diffi- The next question to be considered is the little hope of serving at one of the corn- head of which is the Inspcctor of Wireless tificates, or to work as clerical officers on Buenos Aires, Argentina. cult to see that the prospects of obtaining interesting one of pay.So many adjust- pany's high -power stations, because theATelegraphy.Recruits for this service are the headquarters staff at the G.P.O. Companhia Radiotelephica Brasileira,io7, wtill 15 lucrative employnient are 'very remote. ments, have recently been made, dup to nature of the work they do at such plaCes exclusivelydrawnTromtheranksof The constitution of the Post Office wire- Rua to de Marco, Rio de Janeiro. Yi kit Offiduziegiduc4rgs3iTrrect7Iffic4f2TrTzT. ffitOIDE_Fi-fficT55E.TOfficrElrglfflcf7,0th--100dP-TOfflOgirli3ttliiTdPrffiffiofflil Amateur Wireikss 650 DECEMBER 161922 oftheBritishBroadcasting Company,X = k ,/CxL, where each holding an equal number of shares = wave -length. up toa totalfor the six companies ofk = some constant tp,A Tuning Hint 6o,000 shares. Nofurthercapitalc = capacity. could be issued without the Postmaster -L = inductance. General's consent.The six firms were :Squaring both sides we have k2L F you are troubled with a set that asksThe Marconi Wireless Telegraph Com- xC.Now since k is a constant and L is I for exceedingly delicate tuning on shortpany, the Metropolitan Vickers Electricalalso constant (a fixed inductance coil) the wave -lengths, try putting a blocking con-Company, the Radio Communication Com-expression k2L is also a constant, and may denser of about o.00i mfd. in series with.pany, the British Thomson -Houston Com- benotedbyK,whentheexpression youraerial tuningcondenser. Thispany, the General Electric Company, and becomes X' = K C broadens tuning very considerably and you theWesternElectricCompany'. Any It is necessary to pick up and tune to the will find it difficult to miss signals it was otherBritishmanufacturerofwirelessloudest possible point some station whose almost impossible to find previously with-apparatus might become a member of thewave -length is constant and well known, out a deal of luck.The best way to put itcompany, subjecttocertain terms andsay, Marconi House, Croydon, etc., and to conditionsalreadyagreedtobythe inis to insertit between the output ter- note thecondenser readingindegrees. minal of the aerial tuning condenser andguaranteeing companies.He saw no ob-We are now in a position to calculate K in the input of the aerial tuning inductance. jectiontopublishingthetermsofthe andcondenser agreement between the Post Office and thetermsofwave -lengths Such a condenser can easily be made for degrees.Thus,supposeatransmission a few pence at home.Cut eight pieces ofcompany if there was a general demandoccurs on 360 metres and the condenser the thinnest copper foil to dimensions offor it. ® reading is 4o deg., we have 2 in. by 2% in.Each piece should have = KxC a tongue on the end for connection pur- 360 x 36o = Kx 40 poses. E-itu,ff-.,,_-_-,=2,-,ff,,E About twenty pieces of stout blot- zi therefore K = 9 x 360 ting paper should next be cut to 2,4in. t and our equation becomes V = 3240 C by 2 4in. These should be thoroughlyt t tTheRadioSocietytt (indegrees).By interposing for X any soaked in wax thatis nearly at boilingt tvalues within the range of the coil we can point.Ordinary candle -wax will serve thetof Great Britaintreadily calculate condenser reading corre- purpose.Five sheets of waxed paper are hi hi (The Wireless Society of London) sponding to this wave -length. Iapplied used as a foundation and then alternate hi hi hi this method for tuning in The Hague after copper sheets and papers are laid on one getting Croydon.I set the condenser and another,like.a. Victoria sandwich. The (.-N December20,at6p.m.,Lieut.waited for The Hague and got him, it re- connection tongues projectfirston one quiring only very little fine tuning.This side and then on the other.Five moreODuncan Sinclair, of the Air Ministry, will lecture at the Institute of Electrical methodshouldbeusedwiththefine pieces of waxed paper on top finish it off. tuning condenser (if used) connected up, Whilst the wax is hot the whole should Engineerson "DirectionFindingin Airships."As Lieut. Sinclair was presentbut at 90 deg.It will be observed that be pressed into a solid lump.Pierce the the constant K must be calculated for each tongues at each end and insert small ter-on the voyages of several airships and personally assisted in carrying out tests,instrument by observation on a known minals through each of the bundles of wave -length,andwill,of course,vary four. Wrap the wholein stout brownthe lecture should prove of great interest. During the past month 5o new membersconsiderably. The methodlendsitself paper and the job is finished.To make a very readily to the construction of a curve very complete job of it put the finishedhave been elected, and there are now up- wards of i5o societies and clubs affiliated.for each coil used, and I may say that I condenser in a small box, bend the tongues have found it very useful.-F. G. F. so that the terminals stick up, and pourThe total membership 'of the whole society wax, just in the running condition, overwill soon reach the i,000 mark. With a Single Valve the whole, so that the condenser is em- SIR,-Thearticle" AllonaSingle bedded in wax. Valve," in No. 18, has pronipted me to Don't forget that on short wave -lengths CORRESPONDENCE forward you the following description of you get maximum efficiency by using your my home-made single -valve set on which aerialtuningcondenserinserieswith I receive the Dutch concert regularly and your inductance (coil) and not in parallel. Calibration also F L and 2M T telephony.I also get ERNEST LANGMEAD. has often occurred to me thatall the usual Morse transmissions covered by my tuning apparatus. 0,./.."."....."...eww many amateurs are at a loss to calibrate The set is rather their apparatus, owing to the fact that aroughly constructed, and thetotalcost DciTILTUPtc.--:31±PPIIL_[turfi]cff31171wave meterisnot,ingeneral,withinwas 12s., as under: EEI hi everybody's reach.Igive the following" Magnos " valveandholder for what it is worth to those who use fixed (9s. 6d. and is. 6d.) ...... ito The Broadcasting inductances(suchasslab,honeycomb,Second-hand double head -phones etc.) and tune with variable condensers. (total resistance 2,000 ohms)... 6 6 Company Q1 It is only necessary that a numbered andSecond-hand accumulator (Fuller divided dial be used with the condenser, block) ... too such as may be bought for a few pence.H.T.'battery(flash -lamp refills, IN the House of Commons this week The principle is as follows :The capacity Siemens) ... 7 6 Capt.W. Benn,Liberal member forof any variable condenser is directly pro-Wire for tuningcoil(No.22 Leith, asked the Postmaster -General theportional to the overlap of the plates, and S.C. c.), etc.

26 names of the various firms which werethereforeproportionalto theamountCondenser material and parts 6 o members ofthe Broadcasting Companyswung in as indicated by the pointer onAerial wire (t8 gauge), insulators and the amount oftheirholding. He the dial; thatis, a condenser having a and poles (2 in. by 2 in.) 69 inquired whether the terms of the agree-maximum of,say,0.00Tmfd.with theTerminals and sundries ment betweenthePostOffice andthe plates right in (that is iSo deg. on dial) 9 company could- be published. willhave o.0005mfd.atgo deg.and Z2 120 Mr. Neville Chamberlain, in reply, said0.00033 at 6o deg., etc.The wave -length that six firms had guaranteed the capitalfor any set is given by :. (Continued in third column of next page) DECEMBER 16, 1922 651 tttateur Witvies5 OUR INFORMATION BUREAU Expert Replies to Readers' Questions.Hundreds of Replies are sent by Post. TO ENSURE A PROMPT REPLY PLEASE OBSERVE THE FOLLOWING RULES Write distinctly, give all necessary details and keep to the point.Ask one Question at a time-never more than two.Send a Stamped and Addressed Envelope.Send the Coupon cut from page 654.

Oscilating and Heterodyning a dozen or more steps will be taken and thenlengths.Up to 600 metres 5o turns of No. 36 Q --Is the oscillation of one's valve duringthe men will be in opposite step.That is,S.W.O. d.s.c. copper wire.Goo to 2,000 metres the reception of C. W. necessarily radiatingone man places his right foot down whilst theion turns of No. 36 S.W.G. d.s.c. copper wire. energy from one's aerial, and if so, is it audibleother his left foot.Again they will fall out2,000 to 6,000 metres, 170 turns of No. 36 to neighbours, or is one creating a nuisanceof step, and so on until exactly in step as whenS.W.G. d.s.c. copper wire.All of 'the above only on those occasions when too tight coup- first they started walking.This state of affairscoils should be wound on a 2 -in. former and ling causes a hooting audible in one's ownoccurs in a valve circuit when employing re-may be of the honeycomb coil type.-I.4. C. phones.?-T. K. S.(3029). actance.The reactance coil forming a circuit, A.-Various notes have been published con-which is not tuned resonantly to the aerial O 0 cerning the re -radiation of wireless waves Whenoscillatorycircuit,causes the variations in BROADCAST TELEPHONY using reactance in conjunction with valveanode current to alternate best at the tuned Some of these transmissions are commercial sets.These notes have been somewhat mis-frequency ofitself.These variations beingor official.Wave -lengths and times are liable leading owing to the contributors being at aslightly out of tune with the incoming oscilla-to alteration without notice. loss to explain a difficult subject in terms thattions cause a " beat " effect such as illustrated could he readily understood by the amateur.by the analogy.When the reactance and London B.B.C. Station (.L 0), 369 metres. When a valve set is in operation, and is re-aerial oscillatory circuits are functioning thus,Daily, Usually 5 p.m. toin p.m. ceiving signals of any category, the valve itselfthe circuits are said to be heterodyning.If ManchesterB.B.C.Station (2ZY),385 is really oscillating.Keep this in mind fromthe reactance coupling to aerial is tight, oscil-metres.Daily, usually 5 p.m. to to p.m. the outset, and a better understanding of thelations induced into the aerial are strong. BirminghamB.B.C.Station (2W P),425 subject will be formed.By oscillating it isOnly a small percentage of this oscillatory metres.Daily, usually 5 p.m. to lo p.m. not intended to convey that the valve is re -strength is required to make up for the resist- Croydon (G E D), goo metres.Daily. radiating.It simply means that the incomingance losses in the circuit to maintain a Lself= Writtle (21\1T), 400metres. Tuesdays, signal which formsanoscillatory" currentoscillation and consequently the surplusis 8 p.m. functions between the grid end the filament ofradiated away ,between aerial and earth.It Eiffel Tower (F. 2,600metres.Daily, thereceivingvalve.Thisinturncausesis noticed when a very tight coupling is em-6.20 p.m. to 7 p.m. variations of current in the plate circuit of the ployed the valve starts tohoot " or 'howl." The Hague (P 'C G G), i,oS5 metres. SU:1- valve.ThesevariationsareoccurringatAn explanation of this is, the super -imposeddays, 3 p.m.to 5 p.m. oscillation from the reactance is so powerful Rome (I C D), 3,200 men-eq.Daily, io a.m. exactly the same frequency as the incoming Konigswusterhausen(LP),2,80ometres. oscillations, but instead of alternating posi-that it causes the valve to generate its ownDaily, 4 p.m.to 5.30 p.m. tively and negatively above and below theoscillations.If amateurs understood that the Amsterdam (P C A),1,800 metres.Daily, filament potential line, are alternating con-valve howling for only a few moments causes 1.10 p. m. sistently at a positive potential to the filament.greater loss than burning the valve in an or- Haren (0 P V H), 90o metres.- Daily,- every These variations in plate current are rectifieddinary manner for several hours, the howlinghour from 11.20 a.m.to 4.2o p.m. by adjusting the steady grid potential in theof valves would be reduced to a minimum. C. usual way to enable the current to operate the telephone receivers.Now, when a re-Particulars of Tuning Coils. actance coil is inserted between the plate of Q. --Please give a list which will enable me CORRESPONDENCE (continuel from page 65o) the valve and the positive terminal of the plateto build up a complete set of coils constituting In addition to the foregoing is the licence circuit battery, an extra duty is performed.primary, secondary and reactance to, tune be-of los.My aerial of twin wires is slung By coupling this reactance coil in such a mannertween roo and, 6,000 metres.-P. B. (Southfrom a is -ft. pole (2 in. by 2 in. red deal, to the oscillatory circuit or aerial tuning cir-Wales) (5148). cuit, the variations in the plate current caused A.-The following lists may be taken asplaned and painted) on to the back kitchen by the valve oscillating, induce a correspond-approximate when used in conjunction ,withchimney, total height from ground about ingvariationintotheoscillatorycircuit.variable condensers as follows :-.001 plicl. for3o ft.The far end isto a similar pole This induced variation from the reactance intothe primary tuning coils, and .0005 infd. for20 ft. high.Length of aerial about 36 ft., the oscillatory circuit may be termed a super-the secondary tuning coils, imposed oscillation.This operationcauses 200 to 600 metres, 70 turns of No. 26 s.w.G.and down lead about '15 ft. 1 in. ; bamboo the valve to maintain a self -oscillation in thed.c.c. copper wire. spreaders, 4ft.6 in. long, are used at oscillatorycircuit.Beforeproceedingfur- Goo to r,000 metres, uo turns of No. 26each end of aerial with reel insulators. ther, an analogy will serve as a simple explana-s.w.G. d.c.c. copper wire. My valve panel is constructed from two tion.Imagine two men walking along the 1,000 to 1,700 metres, 170 turns of No. 26 7 -in. recordsand road together.One istall and takes longS.W.G. d.c.c. copper wire. gramophone isstill strides, the other is short and consequently 1,70o to 2,50o metres, 235 turns of No. 28 going strongaftersix months'service. takes short strides.At one moment eachS.W.G. d.c.c. copper wire. The records require just ordinary care in man will be correctly in step ;a short time 2,500 to '4,000 metres, 37o turns of No. 28drilling, and can he held down for this later the men will be out of step.PossiblyS.W.G. d.c.c. copper wire. operation by a screw through centre holes. 4,000 to 6,000 metres, 55o turns of No. 3o S.W.G. d.c.c. copper wire. I am 'using discarded fountain pens for "RECTIFICATION BY.CRYSTAL " (cont. from p. 636) The above will be suitable to use as primaryextensions and tuning handles on con- The area of the positive half -cycles, a'-a6tuning coils. densers. A week or two ago I heard part are very much larger than the area of 200 to 600 metres, 150 turns of No. 3o S.W.G.of the Teddy Tail story -reciting, " Three d.c.c. copper wire. negative half -cycles bi-b6, and the dis- 600 to r,000 metres, 23o turns of No. 3oBlind Mice," etc., also announcements of charge of the condenserisdue totheS.W.G. d.c.c. copper wire. the items.Needless to say Ialso hear differencebetweena1-a6,andb'-b5, 1,000 to 1,700 metres, 350 turns of No.. 32from some of the local atmosphere dis: because the charge due to the latter annulsS.W.G. d.c.c. copper wire. turbers, whose howls areanything but 1,700 to 2,500 metres, 48o turns of No. 32welcome on these occasions. some of the charge due to the former. S.W.G. d.c.c. copper wire. I have also Thus each wave train sets up a uni- 2,500 to 4,000 metres, 75o turns of No. 32been experimentingwitha home-made directional rise and fall of current throughS.W.G. d.c.c. copper wire. loud speaker, constructed from a micro- the telephones, which will' result in the 4,000 to 6,000 metres, T,I00 turns of No. 32phone and earpiece belonging to a house diaphragm being attracted and releasedS.W.G. d.c.c. copper wire. telephone set.With the horn of a gramo- These will he suitable for a set of secondary once' for each wave train. C. E. N. R. tuning coils..A set of four reactance coils willphone attached, and placing one of the (To be concluded) be quite suitable for the above range of wave-H.R.. earpieces over the microphone, I get tnateur Winless 652 DECEMBER 16, 1922 Paris clock ticking just like a grandfather reception ofthespecialtransmissions from Paris because the fact that and Northolt, and these came through at 4 and 7 clock,alsoLeafieldon portional to p.m.,bothwishingtheclub everysuccess. The C W ("har- x + y, set used for the reception of these messages was monic " about z,000 metres).-V.E. M.it increases out of proportion with increase unique, same having been built by one of the club members who is totally blind.Itisin the form of (Shrewsbury). of E.M.F. does not interfere with the cal-a bureau with lid,and has a three -valveset con- culation, as each transmitting station will taining one H.F., one detector, and oneL.F.The Experimenting with Crystals w orkmanship and general finish of the set is splen- be sending on a definite and not varyingdid, and gives particularly good signals.Concerts SIR,-With reference to the articles on Were transmitted at regular intervalsall day from pressure.For two resistances in parallelan adjoining hall, and received in loud -speakers and experimenting with crystals in the issue ofthe total resistance is equal to headphones at a number of the exhibitors' stands November 4,I in the main hall.By three o'clock the hall was so should like to point out R, X R2 packed that it was found necessary to stop admit- thefollowing :assuming the resistances ting visitors for a short time, but after the lecture + R2 by Professor Howe on " Wave Transmission," which of the crystals are to be of equal value =If we consider the four crystals in Fig. was enjoyed by the few who managed to squeeze x.Let y represent the resistance of the intothe lecturehall, those who had been infor (page 487) in pairs in parallel the resist-some time, and had been satisfied in what they had remainderofthecircuit. The currentance of the crystal circuit alone is equal seen, were asked to kindly make room for the queue which was lined up outside.Not the least success- through one crystal can be taken as pro -to ful part of the exhibition was the fact that arrange- ments had been made for the taking of the names 2X X 2% __ 4%2- X of new members for the club.During the day about 2X + 2X 4% one hundred names were taken, practically doubling theclubmembership. Allthingsconsidered,the EXTRA 'PHONES FOR CHRISTMAS so thatit' will be seen from this that the show was an undoubted success, and gives the club great encouragement for holding a similar exhibition YOU CAN AFFORD THEM current through the whole is proportional at some future date, when no doubt the experience AT THIS PRICE gained at this their first exhibition will be valuable. All your friends will want to "listen in."Snap this to the same as for a single crystal, special offer now.7 hree pairs for price of one ! x + Croydon Wireless and Physical Society. Genuine Sullivan Headphones. Double, com- and thereis apparently no advantage atHon. Sec.-B.CLAPP, Meadmoor, Brighton Road, plete with double adjustable headbands and cords, APTurla 020 ohms.Perfectly new.Each pair in box.Ideal all to be gained by this method of con- eeting of the above society, held on Nov. 4, present for " Wireless" friends. nection. If,however, we considerthe Mr. S. H. Naylor gave a most interesting lecture on POST " HintstotheStudent and Teacherof Wireless 2in Or 3 PAIRS FOR 35/- case of two crystals in parallel (Fig.2, Telegraphy." Mr.Naylorexplainedtheeasiest FREE I "-''Cash with Ostler. stock lasts. page 487) we have waystostudythesubject,and emphasisedhis F. HARRISON, 46 Brooke Road, WALTHAMSTOW, E.17 pointswithseveralanalogiesand. demonstrations x x x X2 with simple models.The secretary will be pleased = togiveparticularsofmembershiptointending X + X 2X 2 members. and the current is proportional to - -- Fulham and Chelsea Amateur Radio and Social ACCUMULATORS x + y Society. 4 volt 20 amp....14/.6 volt 20 amp....22/ - 2 'Iambic Street, Fulham, Hon. Sec.-R. Woon, 48, 4 40 19 . 6 40 ... 27/6 S.W.G. 4 60 ...27 - 6 60 37/6 2 AT a meeting held on Nov. 7 the members, with the 491 6 80 52.'- or C, : (Carriage Paid) (Carriage Paid) X = 2y, +I .v zy aidofafive -valveset loanedby oneof them, These accumulators are band new, guaranteed and attempted a pleasant and instructive evening, but specially recommended.Terms Cash withOrder. 2(x + y). owing to severe disturbances from a local generator C2 = C1 If we give valuesit was found impossible at the time to get atall BASTONES,228,PEN EMILE RD , KINGS CROSS. LONDON. N.1. x + zy clear signals. as before x loo,000, y = 4,000 = C, Mr. Whittsinthe meantime read and lectured from one of R. D. Bangay's books. 2(104,000) OFFER OF 1.9.Or we may say that the io8,000 - Streatham Radio Society. Hon. Sec.-S.C. NEWTON, " Compton," Pendennis GUARANTEED GOODScurrent through two crystalsin parallel Road, S.W.16. Eeergthing for Wireless is twice that of one.-J. T. B. Ox Nov.Is Mr. Bevan Swift gave thefirstof a Combined Crystal and Valve set B.B.C. stamped 7o mile range, with series of lectures specially arranged for the younger phones, valve, batteries, zoo ft. aerial wire, insulators, lead.,,, tube, earthing clamp and including all royalties, £9. Accumulators 4.0o, 15/.; amateur.Some of the more experienced, however, 4'40, 20/.; 460, 25/; 23/-;6'40, 31/.: 6'60,39/0.H.T. received an excellent " brushing up " on the less Batteries r5 v. Multif Plug, 36 v. 6/., 63 v. 10., Aerial wire 7/at., 4/3, complicated fundamental wireless laws, such as the 3;22, 3/3Double headpliones4,0oo ohm, 27/..All instrument wires. relationof wave -length to frequency, etc. Hertzite, 1/.Zincite, ualena, Carborundum, Bornite, etc. 6d. each. THE LIVERPOOL WIRELESS CO., 10S, MOUNT PLEASANT, LIVERPOOL NorthLondon Wireless Association. CLUB DOINGS Hon. Sec.-V.J.HINKLEY, NorthernPolytechnic, EASY TERMS OR CASH N.r. Further reduction. No extra charge for extended payments.L.F. Onnnnniv ON Nov.zo Mr.II.Norman Wilsondelivereda Transformers, 15/6 & 20/..Mullard Ora Valves 15/..Double lectureontheconstructionoftelephones. Headphones, Brown's, Feeling's 4.000 ohms,52/..Mula,d's 4,000 Mr. slims, 30/.. Best French 4,000 ohms, 25/. & 30/-.British 4,000 Glasgow and District Radio Club. Gilson had actually constructedhisown phones, ohms, higtgy sensitive, 20/. & 22/6.3 way Coilholders, 13/6 & Hon. Sec.-W. VUILL, 93,, Holm Street, Glasgow. and was therefore well able to speak on the diffi- 17/6, a tea,, 7/6,Single Holder 2/6. Honeycomb Coils list, price A HIGHLY successful exhibition was held by the club culties to be overcome by anyone desiring to under- according to wavelength.Variable Londensers, complete sets parts, top and bottom, oor 0003 6/6. Accumulator,4 volt ao amps,17/,, inthe McLellan Galleries,SauchiehallStreet,on take the job.The main difficulties, he stated, were 3o amps, SSW, 8o amps.40/, H. C. Battery, 30 volt 7/6,6o volt 15/.. Nov. 4.The special features were the large tradeto obtain sufficiently strong permanent magnets and Polished Mahogany Cabinet, with Ebonite Papel. drilled, for Single show,all the latest in wireless being exhibited byto wind and solder the extremely finewire on the Valve Set 8by 6, 10/., two Valves. to by 8. 15/6, three Valves t4 by bobbins.In his case, to make the permanent mag- 21/. and terminals.TermsOne-third with order, balance in six abouttwentyfirms,thelocalfirmsbeingvery fortnightly payments.Carriage paid on all orders over 40!.. Money prominent.The club members' show was also fairlynet he had wound the hardened steel with several returned In full if not completely satisfied.Other accessories for cash large,alltypes of ancient and modern apparatus turns of wire and magnetised it by connecting- it to at lowestprices. being on view, and the workmanship of some was ofa charging dynamo. 0. BUSH, 119, Sutherland Avenue, London, W.9. high order.Arrangements had been made for the (Continued on page 654) XMAS POST FREE OFFERS. HIGHEST EFFICIENCYCRYSTAL RECEIVING SET forBROADCASTING CABINET CRYSTAL RECEIVER, OAK CASE, 35/11. I(Range over 20 miles) Coil wound on Ebonite, polished mahogany base.Dust proof sensitive detector, Baby Crystal Receiver, 19/11.4,000 Double Headgear, 31/11. condenser spare crystal in cap.Approved by P.M.G.,PRICE COMPLETE 30 v. H.T. Unit, 7/11. 60 v., 14/11. incl.royalties, 33/6 (highest grade).Headphones, 4,000 ohms, single 10/6; double,20 6and32,6. COMP ETE OUTFITS(inchtooft.7'22 WOE, 6 v, 60 amp. Accumulator, 40/11.100' 7/22 Copper Wire, 5/6. insulators, leading -in Aerial Insulators, each 6d. tube) with single phone IVEL WIRELESS SUPPLIES, 33 Middle Street, YEOVIL. 50/-,with double, 60/- FOR TORRE BE ENRNI & 70,- all ALLREQUIREMENTS RENTER post free. AT MOST REASONABLE PRICES. COMPLETE SETS OF PARTS SUPPLIED, SPLENDID FROM CONDENSERS TOSUPER -REGENERATIVE SETS(IN STOCK). testimonials. IN ATTENDANCE, EXPERIENCED RADIOENGINEER INSTRUMENTS REPAIRED,ETC. All sets tested. Immediate JOHN BANKS & SONS, delivery from 14-15 Duke Street, workshop. (5 minutes from CENTRAL STN.) 'Phone 4424 Royal. IVERPO W. J. PDLYDOROFF, A.M.I.E.E."'' (See WIN DOWS.I DECEMBER 16,Ion

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All Models can be Inspected and Heard at the Head Office and Branches of I WALTURDA CO., LTD. MARCONIPHONE DEPT.: THE 46 GERRARD ST., LONDON, W.I. BIRMINGHAM.LEEDS.MANCHESTER. LIVERPOOL.CARDIFF. NEWCASTLE -ON -TYNE.SCOTLAND. SOLE AGENTS IN THE UNITED KINGDOM For allPlaces of Public Entertainment. DECEMBER 16. 1922 emoketir Wireless 654 CLUB DOINGS (continued from tage 652) THE secretary will be very glad to hear from intend-anditsapplication as a detector.Next, the con- ing members.All ladies and gentlemen interestedtrolling effects on the electron stream, obtained by Oldham Lyceum Wireless Society. are made welcome to the meetings, which are heldthe insertionof the" grid," were shown, and the Hon. Sec.-GRAii.km HULBERT, 16, South Hill Street, every Friday eveningintheY.M.C.A.,Claypath, increase-inefficiencyandrangeofapplication Oldham. Durham, at 7.30 p.m. pointed out.

ON Nov. 16 Mr. J. Holden lectured on "Recording Wireless Signals."In his lecture Mr. Holden went Ilkley and District Wireless Society. Stoke-on-TrentWireless and Experimental right backtothe beginningofwireless, and ex- Hon. Sec.-E. S. DossoN, " Lorne House," Richmond Society. plained how a recorder could be used and had -beenPlace, Ilkley. Hon.Sec.-F.T.joNEs, 36o, CobridgeRoad, used with such old friends as coherers.The nextON Nov. 20 Mr. D. E. Pettigrew, secretary of the Hanley. step was the crystal, and the lecturer showed howLeeds and District Amateur Wireless Society, gaveTHE secretary of the above society will be glad to a recorder could be brought satisfactorily into thisa lecture on " Maritime Radio Communication." The hear from intending members. type of detector circuit.He then went on toex- lecturer commenced by tracing the development of plain in great detail the theory and action of mostwireless as applied to ship practice from the earliest Walthamstow Amateur Radio Society. present-day recording machines. experiments of Marconi.The utility of wireless aslion. Sec.-R. H. COOKE, Ulverston Road, E.r7. Wireless Society of Hull and District. a means of communication between ships and from ON Nov.zs Mr. Cooke gave a lecture, illustrated ship to shore was explained, and also the method by manydiagrams,on"Radiatingand Non - Hon.Sec. -11. NIGHTSCALES, 79,BalfourStreet, ofhandling messages. Mr.Pettigrewthenpro- radiating circuits."He drew several non -radiating Holderness Road, Hull. ceededto describe indetail the various types of circuits,includingcircuitsconformingto the A MEETING of this society was held on Nov. 13.Mr. transmission and receiving gear tobe found onP.M.G.'s regulations. G. H. Strong read a paper entitled "The Calcula-ships, from the magnetic detector and plain aerial tionof Capacity,"in which thelecturer describedspark transmitter to the modern multi -valve receiver the way to calculate the capacities of many different and C.W. transmitter. types of condensers and gave many useful formula. ANNOUNCEMENTS Blackpooland Fylde and Lytham St.Anncs Edited ScientificSociety. AmateurWireless andElectrics." by PlymouthWireless and Wireless Societies. Bernard E.Jones.Price Threepence.Published on Hen.Sec.-G. H. LOCK,9, Ryder Road,Stoke, Hon. Sec.-C. S. DOEG, " The Poplars," 6, SeventhThursdays and bearing the date of Saturday Hume. Devonport. Avenue, South Shore, Blackpool. diately following. itwill be sent post free to any ON Nov. 22 a demonstration of telegraphy and tele- PERSONS interested in the above society are invitedpartoftheworld -3 months,45.oct.:o months, phony was given at a bazaar and fete in aid of the to write to the secretary. 8sod ;is months,17s.rid. Postal Orders,Post funds of the Service Men's Y.M.C.A.With a seven - Office Orders, or Cheques should be madepayable valveset and Magnavox belonging to Mr.S.F. Tottenham Wireless Society. tothe Proprietors. Cassell & Co.Ltd. Heal the5.10 concert and weather forecast from Paris were made audible to a large audience.In Hon. Sec.-R.A.BARKER,22,Broadwater Road, General Correspondence isto be brief and written Bruce Grove, N.17. onone side ofthe paper only. AUsketches and the main -hall of the building, through the kindnessON Nov. 22 a lecture on " Aerials " was given bydrawings to be on separate sheets. ofMessrs.Tregilgas,Gundry, Brand and Lock, quite a good exhibition of modern wireless receivingMr. Hall.The lecturer fully explained how to make Contributions arealways welcome, will bepromptly apparatus was gives a substantial mast, also how to erectitcorrectly, considered, andifused will be paid for. after which lie went into the smaller but important Communicationsshould be addressed,according ro Ipswich andDistrictWirelessClub. details. theirnature,toTheEditor,TheAdvertisement Yon. Sec.-II. E. BARBROOK, 40, Foundation Street, 1:onageror ThePublisher, "Amateur Wireless." - Fulham and Putney Radio Society. La Belk Sauvage. LondonE.C. PARTICULARS ofthissociety can be obtained from Hon. Sec.-J. WRIGHT DEwltuRsT,52,North End the secretary. Road, West Kensington, London, W.14. ON Nov.24 Mr.S.G. Calvet gave a lecture on South London Wireless and Scientific Club. "Accumulators and Secondary Cells."He started Hon. Sec.-W. G. ANSELL, 69, Larcom Street, S.E.17. with the earliest form of this type of battery, and ON Nov. zoCapt.deVilliersdiscoursed on his wentcarefullythroughthevarioustypesupto seven weeks' experienceinthe provinces withhis Edison's nickelaccumulator. Mr.Culver had on wireless controlled airship.He started by describ-exhibition a number of accumulator parts. ingthedifficultyhe hadexperiencedinvarious towns of arranging suitable aerials and the marked Ilford and District Radio Society. contrast inthe results on aerials arranged under Hon.Sec.-A. E. GREGORY, 77, KhediveRoad, varying local conditions and his methods ofover- Forest Gate, E.7. coming same. ON Nov.16 Mr. A. E. Gregory delivered a lecture on the " Elementary Principles of the Valve."Ex- Durham City and District Wireless Club. plainingbrieflythe electrontheory and the emis-Querist's Coupon Available until Hon.Sec.-G. BARNARD, 3, Sowerby Street, Sacris- sionofelectronsfromhotbodies,thelecturer ton, Durham. proceeded to the theory of the two -electrode valve Saturday, Dec. 23, 1922

BROADCASTING RECEPTION SETS 5_ ONE VALVE SET COMPLETE FOR 'WORKING, £7-10-0 =OWEN ,MMOdi SEND FOR CATALOGUE Passed for INCLUDING ALL ACCESSORIES Broadcasting Licence DESCRIPTION G.P.O. No. 1038. Single valve, mounted on polished i-in. ebonite panel with vari- able condenser, smooth acting resistance, grid leak and condenser and all terminals clearly engraved in white, in a mahogany polished cabinet, g in. by 5 in. by 5 in. ... £3 - 15 - 0 A TAPPED COIL for wave -lengths up to AGENTS 90o metres with 2 terminals for coils for any WANTED higher wave -lengths. The coilis enclosed and the tappingsare brought out to an 8 -way switch mounted in the front of the cabinet.

MmO ACCESSORIES INCLUDED Siemens 54 volt high-tension Battery with plugs for altering the voltage 15 - 0 4 volt 5o amp. hour low-tension Accumulator in case with carrying strap 1- 4 - 0 One pair of Sensitive Head Phones of 4,000 ohms resistance,.. 1 - 1 - 0 One Detecting Valve . . 15-0 SATISFACTION GUARANTEED TOTAL ge7 - 10 - 0 OR MONEY REFUNDED a

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GECoPHONE GECoPHONE GECoPHONE CRYSTAL SET Jo. 1 2 VALVE CABINET SET DE LUXE CRYSTAL SET No. 2 Approx. range (with standard Approx. range (with standard Approx. rangewith standard P.O.Aerial) 25 miles. P.O.Aerial) ion miles. P.O. Atrial) 30 miles. Price Complete g510 0 Price Complete 250 0 Rice Complete£9150

(REGISTERED TRADE MARK) SOLD BY PRINCIPAL ELECTRICIANS, STORES and IRONMONGERS Manufacturers(Wholesaleonly) THE GENERAL ELECTRIC CO., LTD:,MagnetHouse,Kingsway.London,W.C.2. DECEMBER 16, 1922 Ontateur Ws 656 IMPORTANT WE HAVE OPENED VERY COMMODIOUSPREMISES AT 54, Gracechurch Street, E.C.3 forthe demonstration and saleofalltypes ofWireless Receiving Sets and "Claritone" Loud Speakers. Amateurs and Experimenters will he able to obtain every partrequired for any type of Set including ; Transformers, L.F. and H.F Valves, M.O. and Milliards Headphones, al,types, all resistances Brass W.O. and TelephonetypeTerminals, Condensers, variable and fixed, all capacities Nuts, Washers, Contact Studs and all other parts Vario-Couplers and Variometers Accumulators Coil -Holders and Coils Dry Batteries Anti -capacity Switches,all types Aerial Wire Rheostats, all types Insulators Radial Switches, 5, 10 and 15 way Hertzite and Galena Crystals Ebonite Valve Holders, Dials, Scales, other Cotton and other Tubings, all colours parts and in sheet Etc. etc. PRICE LIST ON APPLICATION PETTIGREW & MERRIMAN, Ltd., 122-124, Tooley Street, London, E.C.1 Note: 54, Gracechurch Street is a few minutes from Monument, Eastcheap, Bank, CannonStreet & London Bridge TELE. :HOP 134

Crystal Receiver 2 Valve Receiver Range 25 to 30 miles 1Detector. 1 Low Frequency Amplifier This Model is a cheap and efficient Range, 60 to 80 miles "A HAPPY RADIO CHRISTMAS' receiver TuningCoil wound onon insulated SPECIFICATION.-Tuning Coil wound former with 24 8.W.G. Enamelled Wire on an insulated former with54 S.W..i. with 5 tappings to studs. Wave -length for those who buy our B.B.C. Sets. enamelled H.C. Wire, having a wave -length range, 130 to 800.Variable Condensers. range of 130 to 1,itu0 metres.Tappings 110,5 Mid.Main Tuning Condenser. taken off to 111 studs.Variable Condenser. Single Moving Plate Vernier Condenser. -5003 Mid., tuning in series.,001 Mid. '0003 Mfd. Grid Condenser,2 V. Grid No. 1 Receiving Outfit,comprising Crystal Re- Blocking Condenser across telephone ter- Leak. '001Mid. Fixed Condenser ceiver (P.O. No. 26q),tted in hands,)me sloping cabinet minals. The wholeismounted on an across Primary of Low Frequency Trans. Ebonite Panel, 71 in. x 5i in. x t in., en- former.'0111 Mid. Fixed Condenser with finely tapped inductance coil, enclosed detector fitted graved and mounted in Poli4h-d Mahogany acro.s Telephones. Low Fraquenoy Trans Case, 6 in. deep.Complate with Sterling former, Ratio 54 to 1, Mounted on 8 in. x 12 withthe wonderful HERTZITE CRYSTAL, certain 'Phones, Aerial Wire, Insulators, Lead-in in, xin. Ebonite Panel, engraved and in results ;one pair splendid 4,000 ohms 'Phones, Aerial Tube. CASH PRICE as 10 plus Mahogany Case41in. deep. With Sterling Wire, Insulators, instrongbox, Royalt,es, Tie Telephones,Aerial and Insulators, etc. and instructions. POSTFREE£3 lOs_ Note Magnification Panel _gel() 10plus Royaltlee. SPECIFICATION.-Low Frequency Transformer, Rato fek to 1, wound with 3 -Valve Receiver THIS WEEK'S SPECIAL BARGAINS. 8.8.0 Copper Wire.Filament Resistance 1 Detector. 2 Low Frequency Amplifiers of 5 ohms.Mounted on an Ebonite Panel, Aaabove but with extra stage of amplifi- ballaction,Hertzite 6 In. a ,%in. in Polished Mahogany cation on Panel 14 in. x12in x en- (1) Enclosed Crystal Detector, 7 in. x graved and in Mahogany Case 44 in. deep. Crystal . ... 4s. 6d. Case. PRILE /..CASH plus Royalties. (2)Broads-Ast Receiving Unit,TappedInductance Supplied up to 3 stages of Note Magnifi- 3 -Valve Receiver on Panel ...... 12s. 6d. cation. 1 High Frequency. 1 Detector.1 Low Frequency (3} Splendid Variable Condenser, '0003... 7s. 6d. 4 -Valve Receiver SPECIFICATION. -1) 02 Variable Con- (The Three make a Splendid Receiver.) 1 Detector.3 Low Frequency Amplifiers denser Tuning Primary of H.F.Transformer. As preceding models, Tuning Coil wound on insu ated former 30s. tut with 8 stages of Note Magnification for with 24 8.W.G. Enamelled Wire,Wave- Brown's 4,000 ohms 'Phenes, Special, Loud Speaker reception. Mounted on length mange 130 to 1,200 metres tapped off Intervalve Transformer 158. 3 CollHolders, Extension HandFir Panel,10 in. x 14 in. x 1in.,in sloping to 10 studs.Mounted on Ebonite Panel 108. 6d. Mahogany Desk -shaped Cabint. All Valves 12 in.a14 in.x 3 in., engravedandin on Plugs for Broadcast, 7s. 6d. H.F. Broadcast Transformers, 3s. Od. are sunk in panel, visible from front. Mahogany Case 44 in. deep.This mod -I M 3coils recommended for use when the situation is 4 -Valve, 1 H.F102 L.F. 30 miles or farther from a Broadcasting As above, but with one stage 01 Radio Station. PARTS FOR AMATEUR WIRELESS. Frequency Amplification, and two stages of IDEAL UNITS.TRADE SUPPLIED. Note Magnification. '0002 PA td. Variable MANUFACTURERS OF COMPLETE Condenser tuning Primary Winding of 14,F. WIRELESS INSTALLATIONS Transformer. This model is strongly recom- mended f r reception over long distani es. Agent: Wilton Wireless Co., Ltd. AA the above Models are Approved W. A. HAGGARD, 53, Charles St., CARDIFF. 120-124 HIGH STREET, TOOTING, S.W.17 H. A. WHITE & SON, ELECTRICAL ENGINEERS. 229, Pentonville Road,KING'S CROSS, LONDON, N.1. 'PHONE:STREATHAM 533. Telephones: CENTRAL 5045.HAMPSTEAD7872. HAMPSTEAD 643. DECEMBER 16, 1922 -A BALD STATEMENT657 mateur Wirarss

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Measures 3 in. x 31 in.x 1 in. only. Is Now Available from Stock. Is made and guaranteed for 12 months by THE RADIO COMMUNICATION CO., LTD. Direct from 34, NORFOLK STREET, LONDON, W.C.2. Or at NEWCASTLE: 17,Sandhill, LIVERPOOL: 67, Dale St. CARDIFF: Atlas Chambers, James St. Branches : SOUTHAMPTON: ig, Queen's Terrace. GLASGOW :ro, Blythswood Square.

-THAT MAKES YOU THINKE. P.S. 18 QUALITY " NATIONAL "EFFICIENCY

WIRELESS ACCESSORIES Approved ANOTHER OF OUR BROADCAST RECEIVERSGuaranteed POSTAGE AND PACKING EXTRA by P.M.G. TYPE N. Mk.l. by Us. 3/9 each THE N.Mk.i* is an Agl.N ALL Is ST UM ENTS FILAMENT RESISTANCES extraordinarilyeffi- are tested and cali- FIXED CONDENSERS *0 02 or 3 ... 216 "001 31- cient1 -ValveSet, brated by us before DO,BLE THRO W SWITCHES S. POLE ... 3/- Double 416 leavingthe works, our tuningdevice and acalibration SINGLE THROW 216 316 giving great selec- card supplied. The GRID L AKS 2 MEGS ... 113, WITH CONDENSER 416 tivity and sharpness. Panelisoff -in. CRYSTAL DETEC FORS, Small 3/6 Large 416 Jamming of Signals Ebonite,highly BASKET COLS I SET OF 9 WL 180 to 3500/ 4/9set polished, and all let- is greatly e,iminated. teringis engraved. PLUG IN COILS (2) AND B.F. TRANSFORMER WOUND This Set will receive The cases are wry FOR B.B.C. BROADCASIING 181- the Broadcasting up handsome, being of SINGLE SLIDER CRYST L S. T r B.C.C. AND P.0.1 42/ - special Ebonite DOUBLE SLIDER CRYSTAL SET kFULLY LICENCED/ 631- to a distance of too Black finish, highly INDUC l'A.CE COILS WOUND 22/24 WIRE 41- each miles and the Wave- polished, size 9 in. length Range is 330 y7 in.by31- in. Only the very best Special Quotations to Trade and Factors on Application. to93o metres. It materials are used willthereforere- in the manufacture THE LONDON & COUNTY SPORTS CO., 10, WOODFORD ROAD, E.7. ceive ships and of otii *sets, and we Croydon as well as do not sell rubbish. the Broadcasting...... G P.O. Regd. No. 1042.

PRICE of Receiver, excluding Valve, Royalty, and Accessories,

.g4 Make itaRadio Christmas 1 5 0

Mullard ORA Valve, 15/-;Broadcast Royalty, 20/-. Crystal Receiver, Tapped Inductance-Hertzite Detector ACCESSORIES (best quality), 4 v. 60 a. Accumulator (Hart's), 36 v. H.T. in Handsome Cabinet, results without trouble...27/6 I Battery with Wander Plugs, pair Brown's Phones 4,000 ohms, 100 ft. Aerial

4,000 ohms Headphones ... 19/6 Concert Basket Coils, per pair 2/- Wire 7/22, 4 Insulators, and Coil of Earth Wire.

linervae Transformers... 15/- Crystal Detectors ...... 2/9 PRICE of Complete Installation, including Valve, Royalty, and 40 3 Coil Holders ...... 10/6 H.F. ditto...... 3/6 .

Accessories, £9 15 0. O Note Magnifiers, for adding to existing sets ...... 45/- . TERith Morder: Carriage Hertz to Crystal in Cup-Tested ...... 2/- Cash w AGENTS WANTED. few Single 2,000 ohms Earp ece, with cord ...... 9/6 We are Actual Manufacturers.Come and see our Stock and Works

...... 4:0 Set of 7 "Trinity" Basket Coils 4/6 Advice free with pleasure.Send for our complete List of

SETS AND PARTS. STAMP FOR LISTS :: ADVICE FREE *

THE NATIONAL WIRELESS AND ELECTRIC CO.,

A. S. A. RADIO, 33, Trinity Road Tooting, S.W.17. 7a, Church Road, ACTON, LONDON, W.3. Chiswick 2219_ )ECEMBER 16, 1922 emateur W1s 658 BUY HIM A WIRELESS SET THE X la 'PHONE Crystal receiver, which willpick up anywhere withina 20 -mile radius of Comprising a Crystal Receiving Instrument that tunes Charing Cross Passed byPostMasterandBroadcasting Co.,£3 7s. 6d. to1.500 metres and containing micrometer detector. or withheadriece£1 10s. per pair Phones extra,single, 12/6 each, complete (betterquality, £115s.), mateialsforoval, 8/- to 10/-, accordingto Pr*ce £2 15 requirements. Any handy man can erect by followinginstructions inbd. Smaller size, pr:ce £2 10 Booklet " WIRELESS MADE EASY,"lhewhole outfit at less than five pounds. You can then listen -in to Concerts, Lectures, Sermons, and All mounted on solid ebonite base and stamped B BCand general news at homeinyour favourite chair. approved by the Posimaster- General for the reception of ELECTRIC NOVELTIES AT concerts. One pair of Phones MODERATE PRICES. and one Aerial. - We would state that all our Beautiful Tiepins that light up instruments arefitted with wit,at 16 each (uitge mortmeut to chooseBorn). HERTZITE Crystal. SHOCKING COILS,6/6,8/6, thesupersensitive 1016 each. Cash with order.Deivery in strict rotation.Send your order immediately to MOTORS to drive Meceano sets, 97, QUEEN VICTORIA STREET. on card forhome erection, 5/, BAKER, JAR[OLD & CO1 LONDCN. E.C.4, DITTO, complete, 8/-, 10/6. sa AS ILLU-TRATED, 15 A PARLY PHONE SETS, 30'. pair. MIOMlMMNNMMMMWMMIMMMOSilMMMTh.. TELEPHONE: CITY 2972 HAND LAMPS,as illustrated,small, 6/6; large,10/6. A. MUNDAY, Ltd., LIGHTNINGSETS 59, WATLING ST., E.C.4, 45, EASTCHEAP, E.C.3 oncard,silreadyto tit,up,5/-. B ttery, (One door Queen Victoria Street, :: One door Queen Street) Bd.; bulb, 7d. extra. ACCUMULATORS, switches of ail kinds. French Head Phones, 4,000 ohms £1 00 BULBS, various, special,for lightingyour 6 Xmas Yee, small stuck only.Order early. Brown's Head Phones, 4,000 ohms £110 Infact, everything electric.Write for Sullivan's Head Phones, 120 ohms 126 Book, 6d.Or Catalogue, only 2d. - Low Frequency Transformers 126 THE CITY WIRELESS AND Aerial Wire, per 100 ft. 7/22 29 ELECTRICAL DEPOT, Egg Insulators, each 3 17, Hatton Garden, Terminals from, per doz. 1 3 London, E.C.1. samminussommmunimminummommemanoms MATERIALS, TOOLS, AND WORKSHOP SUNDRIES OUR 1923 LIST of above (64 pag is now ready.Wireless experimenters cannot afford to be without a copy.SENT POSTFREE on receipt of PostCard.Ask for Lint Ito. SM/1. GEORGE ADAMS(DAT), 255-6, HIGH H0.1613.10. RN, LONDON,

3c1. post free

Aerial Insulators,Shell Condenser Vanes, other sizes see list. Insulated Sleeving, Type, 2f"x21" Condenser Spacing Washers. Accurate, large 6d. doz., 11 m -m. yard6d. approx., best glaze small . doz. 4d. Inductance Sliders, LOUD finish .. ..each 1/3 Condensers, fixed, 40001 11:-I.00(15 each 2/- with spring and SPEAKER Aerial Insulators,Reel -001to .002 each 2/3 plunger.. ..each6d. Type, 24" dia. approx.each 3d .003to.004 each 2/6 InductanceSlider Aerial Insulators, Strain- Crystal Cups (with screw to fix crystal) ..each 3d. Rod, in 13" er, 21" x li" approx.each 8d. Contact studs (superior finish, 1" x l;", with nut lengths .- each4d. Aerial Leading in Tubes, and washer) . doz. 1/- Ivorine Scales, sturdy ebonite, 6" over- Copper Foil Sheets (uniform thickness, 12' x 3".)each 3d. engraved, n o t all, each 1,8,12" overall, each 2/ - Core Wire, soft iron in straight lengths .. lb. 2/9 printed ..each 10d. Aerial Pulleys, large 51" Coil Mounting Plugs, with screw connectionseach 1/8 Snobs, Ebonite, with tackle, hook and 3 Coil Holders for panel mounting.. ..each12/6 11" diam. ..each5d. bicket each 2/6 Ebonite Engraved Dials ..each 1/6 Low FrequencyTransformers.24s each. Aerial Pulleys, small 21' ..each 1/ - Ebonite Sheet, best quality, light not loaded.. lb. 5/ - For description see catalc Accumulators (Oldham's Special Process) - Filament Rheostats for Panel Mounting, the best Paraffin Wax.. .. lb. 1' - 4 volt 40 amp. LC. ..each 20/- offered each 3/6 Resistance Wires, 22 and 24 S.W.G. and 4 volt 60 amp. I.C. ..each22/6 Grid Leaks and Condensers (tested.. with proper enamelled 28S.W.D. ..yard Id. 6 volt 80 amp. LC. ..each 27/6 instruments) ..each 5;6 Screws (brass) from 2d. doz. 8 volt 6amp. LC. ..each 32/6 Instrument Wires.Hundreds of miles in stock, Terminals .. .. from 1'9 doz. Brass Rod, screwed, 2 B.A. in 12" lengthseach 5d. competitive prices. Telephone Transformers, 20;- each. For 3 B.A. in 12' lengthseach 4id. description see catalogue. 4 B.A. in 12 lengthseach 9d. Tin Foil, free from lead, sheets 26" x 13" each4d. 5 B.A. in 12" lengthseach 314. Please include ample postage, balance will be returned Valve Pins, complete with nut and washer doz.1/3 Brass Washers, 2, 3, 4 or 5 B.A. ..doz. 24. Valve Sockets, complete with nuts and Brass Nuts, 2, 3, 4 or 5 B.A... doz. 4d. washer .. ..doz.1/3 Batteries, flash Lamp .. ..doz. 5/ - Valve Holders, complete with nuts and

Terminals to fit contacts of flash lamps doz. 21 - washer.. . . eachI/- Condenser Vanes, 21" diem., in .022" hard drawn Valves. Huge stocks B.T.H., 15? -1,MuI- aluminium ..doz. 9d. lard Ora, 15/,Marconi Osram 17/6 Wholesale Distributing Agents for Scotland :- -- Retail Agents for Bradford :- J. GORSTON SINCLAIR &Co., (Dept. A), 24, London Rd., MANCHESTER. The GRAMOPHONE STORES, 47, Waterloo St., Glasgow Works: BERRY STREET. Bowling Old Lane. 'Phone: Central 42o9.'Grants :"Platheram, Manchester." DECEMBER 16, 1922 659 ematratr Wireiess JAN. 15th Mar On this day will appear the great new Monthly WirelessMagazine "MODERN WIRELESS" ORDER NOW From your Newsagent. 11- net.

This Magazine will be written by Wireless Engineers, edited by WirelessEngineers, and published by Wireless Engineers. Edited by JOHN SCOTT-TAGGART (F. Inst. P., M.I.R.E.), assisted, by PAUL D. TYERS Author of"Construction ofWireless Receiving Apparatus," and E. REDPATI-1, lateWirelessExpertof "Work," and authorofCassell's" Work " Handbook " WirelessTelegraphyand Telephony." of a wireless periodical will not fail to buy the bril- a liant First Number of this Magazine, published by RADIO PRESS, Ltd., Devereux Buildings, Strand, London, W.C.2. BEGINNER'S GUIDE TO WIRELESS Fxplains inplain, everyday language, everything 00E100000*00000*00E*MM*Iii*****000M*11 beginners wish to know about Wireless Telegraphy. HOW TO ERECT, CONNECT, AND MAKE all the apparatus required for reception of telephony or morse, and full instructions and diagrams tor making coils, tuners, and IMPORTANT NOTICE complete valve and crystal sets.112 pages, price 1- post free. TO THE PUBLIC AND TRADE SAXON RADIO CO. (D;g.), South Shore, BLACKPOOL 32 page Catalogue of Wireless Apparatus, 3d. post free. Wireless Sets and Accessories Our policy has always been one of II BUTLER'S BkIT1SH BROADCASTING individual attention and promptness of

CRYSTAL RECEIVERS FOR WIRELESS TELEPHONY, ETC. delivery. Owing to the enormous in- rJ Dimensions A RELIABLE INSTRUMENT crease in business we are now greatly

AT A LOW FIGURE 61 x 6f X S DoubleSlideTuningCoil, extending our organisation :: Spring Contact Crystal Detec- Approximate tor, Engraved Ebonite Panel, This is to give notice of the following changes of address: Weight 3 lb. Lacquered Terminals, the HE 9D OFFICE & WHOLESALE SHOWROOMS whole fittedinto solid, well are now located at- t.pproved by Post- seasoned, polished mahogany Hastings House, master -Genera,. Cabinet. Norfolk Street, Strand, AS ILLUSTRATION Approximate range 3,000 metres London, W.C.2. is POST to which address all correspondence should he sent. £2 -- 6 FREE IF FITTED WITH VARIABLE CONDENSER DEMONSTRATION & RETAIL SHOWROOMS Approximate ra ge 3,000 metres are now located ct- £21 5 posT Eu 179, Strand (Corner of Norfolk St.), - -kJ? FREE * Overseas Postage Extra. London, W.C.2. All that is necessary with these sets is to cofinect up the aerial and earth and All goods are to be sent to our telephones and with small adjustment WAREHOUSE & WORKS- signals should be received. * EXTE A S.-Double Telephone Head Providence Place, Gear, Insulators Aerial and Earth West End Lane, Kilburn, '*1 Wire. London, N.W.6. ILLUSTRATED LIST POST FREE 4d. H. D. BUTLER & COMPANY, LIMITED, * Office:BANK BUILDINGS, 222, GT. DOVER ST., S.E.I.Works: CANONBURY, LONDON, NJ. LESLIE McMICHAEL Ltd. (01,losite Baro Tribe Station) 'Phone: Ho wit.7 clef,: "In,,enuity,'Plzode London." CIMMOCIEMDMOCIOMM**********MM******** (1-mateur **Inks' s 660 li/tt;t1%15tK IS/ZA vmsg411114L0 Do YOU Know Us ?If not, why not2

COMPLETE SETS of PARTS fortinsolieited MAKING VARIABLE CONDENSERSVestimonialS EVERYTHING READY to ASSEMBLE and 0. H. FRASER, Esq., 169, MaxwellRoad, CONSISTS of the FOLLOWING : Shillshall, Glasgow. 1/12/22. Accurate Aluminium Fixed and Moving Vanes, Large and Small Spacer Washers, The condenser parts to hand, and I desire Centre Square Spindle (Screwed Ends, 2 B.A.). 3 Side Rods, 12 Nuts and 12 Brass to thank you for the very prompt attention to my order.The condensers themselves Washers (2 B.A.), Pointer-scale 0-180, Terminals, 3 Bushes, SpringCoil Washers, are of an excellent quality. Best Quality Knob with 2 B.A. Nut in Centre. ALL HIGHEST QUALITY GOODS

T. BROWN, Esq., 2, St. Clair Terrace, REVISED PRICES, WITHOUT EBONITE Annan Road, Approximate Capacity Dumfries. in Micro farads No. of Plates Price 6/12/2Z Received goods this morning. Am highly .0015 85 9/- pleasedwiththem,especiallycondenser .001 57 6/6 parts. .00075 43 5/6 .0005 29 4/6

.0003 19 3/- C. W. DUFFIN, M.P.S.,

15, Silver Street, .0002 13 2/3 Wakefield. .0001 7 2/- 2/12/2 . , . I am very pleased with condenseIS Vernier 3 They are wonderful value.

PLEASE NOTE NORMAN E. CARVILL, Esq., FeroseHall, DRILLED EBONITE ENDS Tonbridge. I purchased some variable condensersoff . you some time ago, andIshould like you 1/- per pair extra to know that I am very pleased indeed with them.They are really worth double, and Postage and Packing, 11- per set.Two sets, 113 the finishis excellent. Owing to the extraordinary value given in above Condenser Sets, we are compelled to make these charges for packing, postage, etc.

Mel c-^wwww RIG HT OPPOSITE Toavoidmistakes, M. RAYMOND this address is close to Charing X Road DALY'S27, LISLE STREET, W.C. 2 and Leicester GALLERY DOOR SquareTub 'Phone . GERRARD 4637 ove".voln.410.".""wAwe Z!Q1C;ft4M3 DECEMBER 16, 1922 661 enuiteur Wireless EVERYBODY We do not offer you " something for nothing," nor is this advertisement a catchpenny one.Goods supplied are value for money, both as to quality and price. We leave our customers to be the best judges. Wuff said !

ALLthe followingGOODS POST FREEat theSPECIAL PRICESattached forPOST ORDERS lf you are not satisfied with value,return goods and we will refund all eearges Filament Resistances.Most wonderful value in the wireless trade. War Office Pattern Terminals, complete with nut and washer, Each 2/6 and 3/6.By post, 3/- and 4/.. 1 8 doz.By post, 2/2 doz. Switch Arms, with polished knob, bushed z BA nut, laminated Splendid Line in 5=piece Terminals, complete with nut and washer, blade, spring coil washer, nuts and bush, 1/., 1/6, 2/. each. good size,1/ doz.By post, 1/6. By post, 1/3, 1/9, 2/3. Large Spacer Washers, 3 doz.,9d.By post, 1/.. Crystal Detectors on Ebonite.Simply marvellous value. Each Small Spacer Washers, 6 doz., 1/=.By post, 1/4. 2/6.By post, 3;'-.Also 3/3; by post, 3:9. Terminals (verylarge),magnificent quality,aerial and earth, Fixed Condensers, with terminals on ebonite, .0003, .0005, .00t, complete with z nuts and 2 washers (a BA stems), 2 for 8d. .002, .003, 1/6; by post, 1/9; .004, 1/9; by post, 2/3. By post,1/.. Oojah Basket Coils, 7 in set, 5/. set.By post, 5/6. Intervalve Transformers (low frequency), high class, tested, and Lead=in Tubes, ebonite, brass ends, 9in.,1:2.By post, t6. guaranteed s -r,14/".each. By post,15/.. Smaller size, 12 in., 1/4.By post, 1/8. 10/6; by post, 11/6. Good Condenser Knobs, tapped 2 BA, at 2/. doz.By post, 2/6. HertziteCrystal,perpiece,accordingtosize,1/3 and1/6. Knobs, with brass nut (2 BA) in centre, high-class quality, 4%,d. Cannot send by post. each.By post, 7d.6 for 2/..By post 2/6. Ebonite Dials, bored in centre with engraved scale o -18o,1/. Crystal Detector, cups enclosed with glass cover, dust proof, 4/6. each. By post,1/6. By post, 5/3. Egg Insulators, 4 for 9d. ;2/- per doz.Not sent by post. Aerial Wire, 7/22 bare copper, stranded, first class quality, not a Grid Leak and Condenser, .0003, very high quality and appear- substitute.Price per too ft., 2/10.By post, 3/10. ance, 3/9.By post, 4,3. Reel Insulators, Id. each.Cannot be sent by post. Inductance Coils Wound Enamel Wire, 12 by 4, 3/'.Not sent mm. Insulating Sleeving, 6 yds.for 2/2.By post,2/6. by post. 12 yds. for 4/..By post, 4/6. Filament Resistance, " Thor " pattern, suitable for one, two or Slider and Plunger, 4d.By post, 7d. three valve sets, 4/..By post, 4/6. Slider Knob, plunger and 13in.rod.The lot, 8d.Cannot be Terminals, telephone, highly finished, with nut and washer, 2/. sent by post. dozen.By post, 2/6. , Aluminium Vanes, 2doz.,1/..By post, 1 6. 5/-gross ;by War Office Pattern Terminals, extra special quality, with nut post, 6/.. and washer, 2/- dozen.By post, 2/6. WE BEAT CREATIONON PRICES AND QUALITY

HEADPHONES. We Don't Sell Cheap and Nasty Telephones Genuine " Brunet " French Telephones, most Single Receivers (French) withcord sensitiveobtainable, 6 Tungsten steel polesin each earpiece.4,000 ohms, with cords (Double 2,000 ohms 9/. (post 1/- extra) Receivers) 251- post free High Class British Receivers, double, French Receivers, 8,000 ohms, double complete with cords and headband Receivers with cords 25/.. postfree 21I- to 251- (post1/- extra) To CALLERS :We Sell All Component Parts CHEAP ! rassRods, Nuts, Washers, Screws, Valve Sockets, ValvePins, Stop Pins at wholesaleprices NOTE !Terms strictly cash with order.All orders by post are despatched at the earliest possible moment, as we have great pressure just now on the postal department

e-PVo"Nedwok., To avoid mistakes, RIGHT OPPOSITE M. RAYMOND this address is close to Charing X Road DALY'S27, LISLE STREET, W.C. 2 and Leicester GALLERY DOOR Square Tube 'Phone . GERRARD 4637 ernateur Wireless 662 DECEMBER 16,1922 THE MARK OF A RELIABILITY JUST OUT 1111111111111111111111=111111 WIRELESS HANDBOOK & DIARY, 1923 FILAMENT POTENTIO. DEC. 30 RESISTANCES METER The ideal gift to all interestedin Wireless. 300 ohms Show this advertisement to your friend who Each was goingto buy you anordinarydiary. Panel Type 4/6 Each PRICE 216 net (post free 2/8). with Knob Panel type A Charles Letts' Diary with 34 pages of general and ISSUE and Pointer. on Ebonite. 40special pagesofwirelessinterest. Beautifully GOES TO PRESS bound in real leather. 1 to 12 volts I to 35 amps VOLT & AMMETER Combined Dead Beat Pocket Type.New and not German. Splendid Instrument in Nickel -plated DEC. 20 Case. Ideal for Testing Cells& Filament Current PPOASIDT 5/6LIMITED VvolvvwwwwwIlAsaINIAVONMS,SlarVU NUMBER PREPAID ADVERTISEMENTS. The Latest Invention.Steam rotary engine, reg. OTHER EXCEPTIONAL VALUES patent.The finest scientific working steam engine Aerial Wire.Bright Hard Drawn, 7'22 Copper, ever invented.rs. each, 3 for as. 6d. --Alan Hitchen, 3.6 per 100 ft. ; same enamelled, 5/. Patentee and Manufacturer, Dept. 17, Burnley.[22 r Aerial Insulators.2 a2tins.Shell type, 9d. Accumulators,plates,parts,accessories.Expert each ;2 in. Reel Type. 2. each. repairs.-Barnard, 45, Great Ormond Street, W.C.r. Telephone Transformers. (Army Type.) 9'. [12 each ; L.F. Transformers, 15J- each. WirelessDealersthroughoutGreatBritainare Vernier Condenser.5 Plate for Panel mount- stronglyadvised tostockpartsformaking up ing,4/.each,'001,16/-. 0.005 12' each. wireless sets, Buy your parts direct from the factory Wireless Jacks.With Plugs, i.- the pair. at wholes -ale prices.-Newtonia Wireless Factory, 13 High Note Buzzer.(Army Type.)Worth andr3, Whitcomb Street, London, W.C.z. treble, 3i- each ; Tapping Keys. 5'6 each. B.A. Screws, .Nuts, and 'Washers,assorted gross, Dewar Switches.D.P.Ch,nge over,panel 2s. ;list, 2d.-J. H. Bennett, Station Road, Willesden type, 2,/- es. ILSmall Switch Arms, 6d. each. Junction. ' Write for "Comple e Supplementary Price List of Excep- All About Wireless.-Sendfor Booklet, 64 pages, tional Values,' sent Post Free.All goods sent Carriage withmanyilltrstratiqus;"-Wireless Made Easy." Paid, but vita Orden under Is. lid add ed. for postage Simple,conciseexplanatiOnofwirelesswonder.tr How to make andfit up at home.Post free, 6d. J.H. TAYLOR & CO., stamps.-The CityWireless and Electrical Depot ELECTRICAL AND RADIO ENGINEERS. HANG IT (Dept.J),17, Hatton Garden, London, E.C. MacaulaySt HUDDERSFIELD. Diu:miteSheet,postfree,anysizecut, f, in. from your table thick,-!,d,per sq.in. ; in.thick, O. per sq.in.-- Telephone 341. Telegrams " Thorough," Huddersfield. Warren andClark, 1.1.A., SidneyAvenue,London, Radio Press Wireless Directory N.13. a 12,000 amateur, stationcall LookatThis,-Lundspeakers,ex -Government ship and land 200ohms,fittedon ebonite base, vial high-class signs.As indispensable as a telephone directory. 24 -in. detachablealuminiumhorn;bargain,30s.; A PERUCT DETECTOR PRICE 2:6 net (post free 2/8). carriage and packing extra.-White,121,Adelaide 3/9 All our publications obtainable through booksellers, Road, Chalk Farm, [3 s FOR WIRE CONTACT or direct from ; L.B. Automatic Morse Senderswill send any mes- PO ST sage airyspeed and willlastalifetime.Makes CRYSTALS Devereux Buildings, the Morse code a pleasuretolearn. Priceonly FREE RADIO PRESS Ltd.I Strand, London, W.C.2. 6s.,postfree. Furtherparticulars ,,,-d. stamped DOUBLEBALL JOINT enr clope. Satisfaction guaranteed.7-Grimshaw's Reg. Design No. 691368 (Dept. A.W.), Legh Street, Golborne, Lanes. [4 s CRYSTAL Huge Purchase of ex -Government -Wireless Stock. Write for list giving full details.150 -watt dynamos, MICKELWRIGHT, Ltd, BROADCASTING "(Jr;hedgehogcoils,3s.6d.;loudspeakers,zoo ALPERTON, WEMBLEY, MX. ohms, 75.6d.;1 -in.spark coils,Los.; spark RECEIVER ins. 6d. ; morse tapping keys, 3s., etc. etc. etc. Three days' approval against cash, or please call.mokimmomommomaimmow PASSED BV G.P.O. Writefordetailedpricelistofall goods.-E. J. Totally enclosed in highly polished Galpin, 16, Loampit Hill, Lewisham, S.E.13, London, Cabinet with accommodation for PORTLAND'S PARTS BY POST Phones. Mounted on Ebonite plate. APPLIAIItt5 bate & Hams). ideal -mu, ma,..oeue SUE NilrIL Optical and ALL RADIO WIRE' LESS PARTS and Materials at Lowest Prices. Price - £2 10 0 Ca 1 and see our immense stock or write for Informationlancl Prices. With 4.,000 ohms phones, roo ft. ht Centre of London, Top ol Inngswa_y "EBONITE" aerial, insulators and lead-in tube. (SCIENTIFIC APPLIANCES, £s. d. Laid. Carriage paid U.K.£4 0 0. 11 and 29. Sicilian Avenue, London, W.C.I. 4 X 4 1 3 12 X 7 52 Valve Broadcast Receiving Set. 7 X 5i 2 8 12 X Si 65 Passed by P,M.G. Tax paid. 8 x 6 30 12x ro 76 69 00. 9 x 6 35 15 X80 ... 8 0 Valve Cabinet Receiving Set. ELECTRADIX RADIOS. I.X 6 3 9 12 X 12 ... 9 0 Passed by P.M.G.Tax paid, rz x5I 4 2 171x Si ... £150 0, 9 X 8i 4 10 14 X 12 ...... 105 IMMEDIATE DELIVERY II X 5 53 18 X it (Hal. sheet) 12 10 r/CCESSOR/ES E SMALL PARTS SUPPLIED. LIST FREE. FROM OUR HUGE STOCKS 7 lb. 30 36 x 13 ...... 130 Our Motto: "EFFICIENCY with CHEAPNESS." _Everything from a Recorder to 28 lb.,£4 an Eurth Clip. C.S. MILLS, The best equipped City depot. No charge for cutting, wasteorpostage135, High Street, Notting Hill Gate, LONDON. Delivery by return of post COME AND SEE US Quality Al. DRILLING, Manufacture, BRITISH 9, COLONIAL AVENUE is WIRELESS BARGAINS. Thickness. one Quarter-Surface, Mat firstopeningonleftin the PHONES, 21/- SUPEiR0S0E0NormIsY,E Minories, nr. Aldgate Station, ALL WIRELESS PARTS & SETS.Trade supplied. Metropolitan Railway. JAMES PORTLAND CRYSTAL DETECTORS, 2/6. 39, SINCLAIR ROAD, OLYMPIA, W.14 LESLIE DIXON & CO., T5f. Illustrated Catalogue A, including list of Stations, N.B.-Mr. Portland Stocks 200 Wireless Parts 6d. post free. 9,COLONIAL AVENUE.MINORIES, E.1. SUPPLY CO.. EONS WIRELESS115, Fleet Street, E.C.4.

FEL OPHONE /2 -Valve RECEIVER for plug in cols in Oak ,...91111111111111111111111111H11111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111t Cahinet,Headphones, Batteries, Accumulator, Aerial and Insulators (Including Tax) £ 12 FELLOPHONE 2 -Valve AMPLIFIER in Oak Cabinet (for Llud RELIABLE RECEIVING HEADPHONES Fs: Speaker), Including Tax -F: g 7 =4 '000 ohms, double bands, complete with flex and tags, =..-7--- SUPERCRYST, CompletewithAerial,Insulators and Headphones, In- = = at 20s. each, post free --- cluding Tax..,£4 7 6 HEADPHONES, 4,000 ohms £1 1 ..7;.: LOUDSPEAKERS. MULLAHD andCOSSOR VALVES, GRID LEAKS. Cash with order. Ex stock. Every instrument guaranteed. E ---- Variable and Block Condensers, Telephone Transformers, £1 1 ,:g - DEMONSTRATIONS. 9 aim. to 5.30 p.m.8 to 9 30 p.m. Ti.---. THE SOUTH'WESTERN WIRELESS SUPPLIES CO :-.=- S N.TURD,VS.9 to r p.m.8 to 9.3o pin. SUNDAYS by appointment. .== 382a, MertonRoad, SOUTHFIELD -,LONDON S.W.ISEz-: F. N, GOUT & CO., Ltd., 31, Upper Brook Mews, Lancaster Gate, near Paddington Station. DECEMBER 16, 1922 663 eft:deur litteles,5

Your Your THE Guarantee. Guarantee. MECCANO RADIO BROADCAST RECEIVING SETS (One, two, three or four Valves) Receiving Set for Broadcasting and Morse Reczption Our receivingsetswill bear the guarantee mark of the Postmaster - General, and are fully licensed under Marconi Patents. HE Meccano Crystal Receiving Set has EFFICIENT SETS AT REASONABLE PRICES. been thoroughly tested and has received Full details and quotations upon application. with great clearness, broadcast music and Besides complete sets we supply numerous component parts for those wishing speech up to 30 miles of London, Birming- to build their own sets. ham and Manchester. PriceLists 3d. post free. Advice and assistance freely given. RAMBLING, CLAPP & Co., 110. Strand, London,W.C, EACH SET IS TESTED AND GUARANTEED 'Phone: Gerrard 8806. EF-ICIENT ON A P.M.G. AERIAL Ass ideal present for Christmas. Give one to your boy and snake him "PERRYPHONES" happy. It is low in cost and complete HEAD SETS FOR WIRELESS TELEPHONY initself,readyto be 4,000 ohms.: connected to any aerial. Send for this Book Our new b )oklet, The, 21/- MeccanoCrlintalReceivinaSet, explains Radio so that every- Every SetGuaranteed. Beautifully one is able to understand finished, highly sensitive, detachable receivers, how simple is the reception of broadcasting, telephony and Morse messages. This Start Radio IMMEDIATE DELIVERY booklet will be mailed free Now in an Efficient on request. and Inexpensive Way Illustrated Wireless Catalogue now PRICES ready, post free, 3d. MeccanoCrystal Receiving Set,complete, price551 Aerial Set(including antenna, lead- THE JEARY ELECTRICAL CO., LTD., in and aerial wires and insulators) ,, 1216 I, LAMBETH HILL, and 97, QUEEN VICTORIA ST., LONDON, E.C.4. MECCANO Ltd Bums Road LIVERPOOL And at Glasgow, Bilininghant, etc.

c= I We reply by return 1=1 9] CRYSTAL DETECTOR [1 LacqueredBrass on Ebonite, Ball and Socket movement. Suitable forSilicon,Galena,etc, Exibe Our BATTERIES money -back 3/ POST guarantee PRICE FREE accompanies ALL our Two Cup Pattern, for Zincite-Bornite, etc. 2 H.T. 11 goods etc., Lacquered Brass on Ebonite, post free '7/ u CompleteEt irelessLists post free Batteries ELECTRICAL SUPPLY STORES,I] for 5, Albert Terrace, King Cross, Halifax to JO, Of CI O ==1 Valve Sets

GENTS' " TANGENT " 24v. 28v. 32v. FILAMENT Type B.K. Owing to the demand for these batteries, RHEOSTAT all orders will be dealt with in strict rotation. STURDY, SOUND Prices approximately oneshilling a volt. AND RELIABLE :: Ask for Leaflet 4030

SEND FOR LA 2 EST PRICES OF Gents' "TANGENT" Filament Rheostat (#0.11iititib ELECTRICAL STORAGE Gents' " TANGENT " L.F. Transformer 4 COMPANY LIMITED, Gents'" DISCOL" H.F.Transformer and other fitments CLIFTON JUNCTION, I 219/229, SHAFTESBURY Radio Dept:, AVENUE, W.C.2. GENT 8 CO., LTD"FARADAY WORKS," Nr MANCHESTER. PRICES AND PARTICULARS ON APPLICATION. LONDON!: 25,VICTORIA ST., 5.51.1. NEINGASTLE-ON-TYNE : TANGENT HOGS, ELACKETT ST. maieu r Wireles5 664 DECEMBER 16, 1922 RADIO CHRISTMAS GIFTS Sterling No. 1 Crystal Radio Head Receiving Phones Set (Manufactured under Brown's Patent No. 134353/18 by Sole Licence)

Of the highest efficiency. Constructed on the mostscientificprinciplesand togive Specially designed for Broadcast reception, very selective and simple to a comfortable fitto the ear of the user. op rate.Complete with one pair( fDouble Head Telephones and with special coil for Paris Time Signals.Range about 25 miles. Write for Leaflets Nos. 321 and 325. Write for Leaflet No. 324. "Co he obtained from all Dealers or direct from WE GUARANTEE that STERLING TELEPHONE & ELECTRIC CO., LTD., all Broadcast Radio Telephone House, 210/212, TOTTENHAM COURT ROAD, LONDON, W.1. Apparatus sold by us conforms Telephone : Museum 4144 (7 lines.) Telegrams :" Cucumis, Wesdo, London." with the conditions of the NEWCASTLE -ON -TYNE : WORKS : CARDIFF Broadcasters' Licence issued by 9, Clan ering Place. Dagenham, Essex. 8, Park Place. the Postmaster -General.

MI NI III 1111 WI III aMI II II IN IN IIIIIII II ill II IC11111 11 II III

Introducing the Registered N? 1045 Passed 1911416

D

D R©

Here's an ideal Xmas Gift-one all the family can enjoy 365 days

in the year.Receives speech and music perfectly, and is tuned

by one knob onlu-no irritating adjustments to make. Further Valves can be added to enable a Loud Speaker to be used.In addition, by the aid of a special Loading Panel-to be attached to

terminals A and E-its present wave -length limits of 300 to 500 metres can be increased to receive Paris and Hague Concerts

Every Instrument accurately tested on an Aerial before dispatch & a signed Certificate attached to ea:h

Size 7 in. by 5 in., mounted on polished mahogany

Cabinet, complete asillustrationbut without Valve. Catalogue of 'phones, loud speakers, batteries and other components sent post free.

OFFICES & SHOWROOXS:

FEATHERSTONE HOUSE,If for use with Broadcast Licence' each instrument 64, HIGH HOLBORN, W.C.1. must be stamped B.B.C. at

an extra cost of 32/6.

gonnen

Printed andPublishedinEngland byCASSELL & COMPANY,LIMITED,Ludgate London, E.C.4.Sole Agents for South Africa, CENTRAL News AGENCY, LIMITED. Saturday, December 16,1022 Gs 404P -.41~-01A040-04~-.4:14.44 -A "Civistmassp" Pumber- A Visit to 2 L 0

No. 29 SATURDAY, DECEMBER 23, 1922 Price 3d.

RECTIFYING' PANEL MODULATOR PANEL

C,Or4TROL AND SUB -- CONTROL MODULATOR VALVES

nLA MEN - TIFy;NG REG ULA'fl NC. VE, RESISTANCES

AMPLiF1ER PRIMARY-CiRcurr INDUCTANCE

5MOOTMNG AMPLIFIER MAIN CONDENSERS CONDENSER DRIVE PRIMARY -CIRCUIT INDUCTANCE

DRIVE CONDENSER

REMOTE -CONTROL SWITCH (NIA;N-POWER)

BROADCASTING APPARATUS AT 2 L 0.(See Special Article on pages 678 and 679.) 4s °*-0-064~~0**144004-)W04~04~-44watirot etnnteitr Wireless 666 DECEMBER 23,192k

CONOMIC LE CTR I LTD. ('-MITCHELFONES Are not a spasmodic production to meet a sudden demand, but have been on the

Have YOU tried the market for over three months, and during " XTRAUDION " VALVE ? this period 27,000 have been distributed to thetrade, and consequently we have the latest and best development of not been able to offer them direct to the the 3 Electrode Valve. retail buyer. RECTIFIES, OSCILLATES 1,000 per week are now available, and we announce AMPLIFIES Its Mechanical Construction DELIVERY FROM STOCK

a makes it a stronger and more lasting You postyourorder,orcallatour valve than any other. premises and get them at once.Think The Filament consumes well under what this means to you-you, perhaps, who half - an - amp. at 4 volts.Anode have been waiting and are stillwaiting. Potential, 50 volts. Its Amplifying Properties are Standard resistance 4,000 ohms, double headgear with doublefoolproofoher:odatraps,comfortable,highlyefficient, wonderful and its freedom from noises and a revelation. Send for Descriptive Leaflet. 254-per pair.

15/- 15/- Special Terms to Traders and deliveries that will surprise you. PRICE PRICE PATENTS PESO INC

MITCHELLS Electrical & Wireless Ltd., We publish the most complete Wireless Postal Address: McDermott Road, Peckham, S.E.15. Catalogue obtainable.36 pages, profusely Retail Address: 188, Rye Lane, Peckham, S.E.15. illustrated, and many usefulcircuitsfor Head Office 10, FITZROY experimental work. Mailed to any address 'Phones: New Cross 1540/1541. SQUARE, LONDON, W.L on receipt of four penny stamps.

Showrooms I Telephone: Branch Showrooms S. Works: )10.-GREAT BRITAIN'S GREATEST WIRELESSSTORE-iiti 303, EUSTON ROAD, N.W.I. MUSEUM 1055 TWICKENHAM VALVE BROADCAST SET No Set to Equal Our Great Registered No. io62.Very compact, of forest British workmanship, and the price includes all accessories. ...Price, £10 0 0 "HERTZITE" Send for lists, postfree, of othersets, amplifiers, components, etc. CRYSTAL RECEIVING SET FOR WIRELESS COMPONENTS LTD BROADCASTING 16,ManetteStreet, Charing Cross Road, London, W.C.2. Inc!tid ng B.B.A. Carriage and Commision 67/6 Packing Free DO YOU READ PRACTICAL BOOKS ? SINGLE CRYSTALS, 2/6 Post Free. VALVES: "ORA," " XTRAUDION," "C.V.C.," & "R.M.R." 15/. each See Cassell's ListofTechnical,Practical and Money -saving Books. A p.c. will ensure your receiving it.

RUSSELL & SHAW9 33, Great James Street, Bedford Roy% W.C.1. =7. CASSELL & Co., La Belle Sauvage, LONDON, E.C.4.

STARTLING REDUCTIONS 0.(4;;4,, Themost sensitive 11111111111111111106111. Ebonite Condenser Dials, Engraved 0-180° and SPECIAL OFFER a tilled wli ite with Knob, Brass Bush and Set Screw2;0 ql" Relay made. Real Dial only ...... 1/6 PlatinumContacts. /,ilinth""""""'4''' Aluminitun Condenser Vanes per doz. ... 6d. Eminently suitable Spacer Washer, small3d.doz.; large 4d. doz. /0 for Wireless work. Knobs, with a BA Brass Inset A.E.G. and Halske Valves for recti. 44',00 Perfeotly new as re- Grid Leaks (enclosed), 2 meg. Eying and amplifying (tested) 7/4 4°. ceived from makers. Grid Condensers 1/6 Crystals (special selected), Bornite, 0 p`b 0 Filament Resistances ... 3/8 Zincite, Galena'SiliconCarbor- Crystal Cups with Screw ... undum, Copper Pyrites, 'Graphite, Fusible Alloy, per stick ... Tellurium, etc. 6d. 0 Price201.each ... 4d. Inductance Tubes, is'X 3 ... Egg Insulators, Green NOTE :- Originallycost Postage and packing, 1,V. 12. X 4 ... 9d. Reel best quality.- ...3d. to 12. x 5' ... Hellesen 36 v. Batteries with Tap- the Trade£8 £10 each. DELIVERY PERRETURN. it 12X6'...13 pings and Wander Plug... 8 6 Sliders and Plungers Essex 15 v. H.T. Batteries...... 3/ - Sq. Brass Rod, 12' X f' X Ebonite Leading In Insulators ...110 Enamelled Wire, 23 gauge, lb. ...2/- Perikon Detectors on Ebonite Corn- Aerial Wire, 7/25, Stranded, too' 3/ - plete with Crystals ... 4/- WESTON MOVING COIL RELAYS Valve Holders, Screwed Legs ... 9d. "UbiqueCrystal Set Complete... 15/ - DELIVERY BY RETURN GUARANTEEDPostage extra. THE GRAFTON ELECTRIC COMPANY, Office & Showroom.. 499,GROVE GRENE RD., 54, Grafton Street, Tottenham Court Read,

THE ESSEX WIRELESS CO LEVTONSTONE,E.11. LONDON, W.1. Telephone-WANSTEAD 749. (1 min. from Station, G.E.R.) Telephone : Museum 241. Telegrams : Grafectric Eusroad London. No. 29 December 23, 1922 No Re -radiation this Christmas! Ensure Peace and Goodwill to Your Brother Experimenters THERE are complaints in all parts ofnot comply with the regulations, becausetightened,watchbeingkeptforthat the country just now about the amountthe primary coil is the middle one of thepeculiar tinny sound which betokens that ofinterferencecaused,particularly onthree and is thus directly coupled to thethe set is about to oscillate, wave -lengths in the neighbourhood of _tooreaction.In thiscase the remedy isas Reaction well used is a splendid thing metres, by those who allow their sets tosimple asitcan be,foritis merely aand one of the greatest helps to the tecep- oscillate.One thing is quite certain aboutmatter of altering the wiring. tion of distant signals.Badly used it is a wirelessenthusiasts,experimentersand But the amateur whose inductances arecurse, not only to the user himself; but to broadcast receivers alike, and that is thatproperly coupled must not be lulled into a hisfriendsandneighbours.Too often notone ofthemwishestospoilthefalsesenseofsecurity,for though thisone meets an. enthusiist who, with the best pleasure of others by interfering with theirarrangementreducesre -radiationtoa intentionsintheworld,boasts ofthe reception.IN'here re -radiation occurs it isgreat extentitdoes not by any meanswonderful loudness of the signals which due usually to carelessness, lack of skill,prevent it entirely from occurring. his apparatus brings in. . or insufficient know ledge of the way in \1T hen he _demonstrates its powers one which areceivingsetworks.In someSearching discovers that he had made a fetish of casesitisno doubt attributabletothe Interference with telephony takes placestrength and pays little or no attention to faulty design of the set it-. clearness and lack of dis- self.If any reader is not tortion.Reaction is pushed satisfied that his set cannot to its limits, with the result cause interference when it that words are inaudible, iscarefully handledthe whilstmusicisfull,of best way of making sure weird.discordantnoises. isto arrange a series of Your setisnot properly tests with a friend whose tuned unless speech and aerialisnearhisown. musicare receiveddis- After comparing watches tinctly and with good tone. he arranges to use the set Overdone reaction makes for five minutes at certain the loud speaker perform hoursoftheday. The worse thana badlyde- friend should listen -in on signed gramophone using the agreed wave -length and worn-outrecordsanda be on the look out for the blunt needle; if the amount slightest sign of re-radia: ofreactioniscorrect,a tion. good set will give nothing Ifitisfoundtotake but sounds that are abso- place duringthe test lutely pure. periodsandnotatany Operating a Four -valve Set. other time, then the set is With care, a receiver with any number of valves may be operated without causing annoy- Some Advice most certainly at fault. ance to others.That care we enjoin upon all readers, particularly at ttis season of goodwill. Never use too large a reaction coil.This is an Official Regulations most commonly whilst the searching forerrorintowhich many amateursfall, The Postmaster -General'sregulationsthedesired stationisin progress.Bothimaginingthatthemoretheimpulses now prohibit the use ofa reactioncoil secondaryandreactioncouplingsarearc "gingered up " the stronger will the coupled directly to the primary or aerialaltered as the user triesto pick up thesignalsbe. Youmayincreasetheir inductance.There arestill hundreds offirst faint sounds, with the result that thestrength a little, but you will also increase sets in use which do not conform to thisset is continually being_ thrown into oscilla-distortion and the possibility of re -radia- requirement, and their owners should losetion for brief periods.The most sure waytion.The reactioncoilshould bethe no time in having them altered.It is, asof avoiding this is to put the reaction coilsmallest consistent with good results.Use a rule, quite a simple business.If thereout of action, either by short-circuiting ita small variable condenser shunted across is no secondary coil the existing primaryof by moving it to the most loosely -coupled it,but keep the capacity as low as pos- may be converted into the secondary byposition, until the transmission has beensible. making its leads run direct to the grid andpicked up.Tuning should be done with If you start your tuning -in when a con- the negative terminal 'of the valve holder;'the primary and secondary circuits untilcerthasbeeninprogressfor_ sonic a new primary coilcan thenbefittedthe signals are at their maximum :strength;minutes,stillgreater careiscalledfor loosely coupled tothe secondary.Somethen, and nottillthen, the coupling of , (Continued at bottom of first column we sets which have already a trio "Of coils dothereactioncoilshouldbegradnallY next lase) mateur Wirekss 668 DECEMBER 23, 1922

Single -wireAerialand Practical the Down Lead Short Double -wire Aerial Aerial Pole and Spreaders Hints Insulators Aerial Wires

THE most common fault of an otherwiseprobably have to come from the top of themake the best of the space available.In well -arranged single -wire aerialis thepole at A, but if the position of the receiv-such a case it would be better to erect the position of the- lead-in from the horizontaling room was low it would be quite im-mast on the house at E (Fig.t) and run a part.Some amateurs seem to think that double wire aerial from G to B, with a lead- itmatters verylittle where the lead-in in from G. wires are attached, and that the middle or Measure off the wire carefully, and so the end are the only possible placesif arrange the spreaders that they can be good work is to be expected.Itisex- pulled to the top of the poles without un- tremely difficult to arrange a lead-in from duly straining them. the electrical middle point of the hori- The pole at E can probably be stayed by zontal wire,for ever solittledeviation a fine bronze wire at F against the pull of from the centre point means that the two the aerial.If you have light aerial wires halves are at variance with one another. you can have light bamboo spreaders, and Even if it has been measured off carefullyFig. 1.-Diagram Explanatory of Aerial Erection, the "flogging about" in a gale of wind to the nearest fraction of an inch, one half, will not be so likely to cause damage. perhaps suspended over the house,has G quitedifferentcharacteristicsfromthe Joints other half, suspended over the garden with Avoid jointsintheaerialifpossible, 20 ft. or 3o ft. more clear space between it making the aerial all in one piece with he and the nearest level. lead-in wire.If you must have joints, see Itis, of course, not always possible to that they are properly soldered and that arrange that the lead-in can come straight the jointed -up lengths of wire are all of from the pole at either end, and if not, the same size and material."Egg" insu- some sort of a compromise must be made. lators are generally light and look neat This would be the case in Fig.t, where when up."Shell" insulators are also very the lead-in, to get the best results, would Fig. 2.-Bamboo Spreader. light and have a greater protective surface. Spreaders AVOID RE -RADIATION (continual from the pre:cd- Choose a light bamboo stick about 3ft. tug page) long, not less, and not a great deal mote insearching, otherwiseyou mayspoil thanrin. thick.See that it has a knot others' reception of most of one item.It near each end.Then in the open reedy would be a good thing if the Broadcasting part outside the knots, cut grooves across Companycouldarrangetohavethe the bamboo as at G and H (Fig. 2.) customarythreeminutes'intervalsat Fig. 4.-Attachment of Insulator. Take three pieces of No. 20 bronze or certainstated times, continuing tosend copper wire, each about 12ft.long, and outawave whilsttheylasted.Late- possible to arrange a good straight lead-infasten them at one end to something solid, comers could then tune in without fear offrom the point A. such as a screw eye in a door post.Take causinginterruption,andthosewhose Similarly from the point B, even if the tuning was not perfect for earlier itemslead-in, together with the aerial, did not could make final adjustments. exceed too ft.in length, the angle at B There is one case in which it is difficultmade between the aerial and the lead-in to avoid re -radiation, and thatis whenwould reduce the efficiency of reception strong continuous -wave signals are comingconsiderably. in on almost the same wave --length as a In such a case perhaps a piece of strong, telephony transmission.Thisisparticu-light bronze wire from A to D might be larly liable to occur in the case of theused with a light insulator at D, and the concerts from Paris and The Hague.Thelead-in be dropped from this point.Even set, though perfectly adjusted to the tele-if the aerial were shortened by a few feet phonic transmission, oscillates in responsethese few feet might well be sacrificed. to the C.W. signals.The only thing to do in this case is to short-circuit the re-Restricted Space action coil, sacrificing signal strength in But supposing that your gardenisa Fig. 3.-Photograph show'ng Wiring of order not to offend. H. R. W. short one, then this construction would not Insulators and Spreader. DECEMBER 23, 1922 669 mattur Wes the three other ends and stretch the wires torepair. Solderingisalmost an im- out equally tight, fix them to the "chuck" possibility unless the whole of the wax is of a carpenter's brace, and, keeping them removed, but by thefollowing method stretched out tight, twist them up tightly Another Phone batteries with loose sockets can easily be into a stranded cable.Take one end of the repaired and put into a condition in which cable when completed and place it at c, they will give excellent service with a running the stranded wire along the bam- Dodge little care.The cell connection should be boointothe notchat H, carryingt'ae first scraped clean of any wax, and then a stranded wire out and back again into the stiff amalgam of zinc and mercury should notch at G with the other end at H. LDIES often complain of the phone be prepared and a little run into the hole. You should now have two strands lying head -banddisarrangingtheirhair. The loose socket should now be put down along one side of the spreader, and a loo seThis state of affairs need not exist if theinto the amalgam and held upright whilst loop extending outwards from the otherphones are simply disconnected from thea little melted wax is run round it, filling side from the notches at G and H.Nowhead -band and attached to short woodenthe hole.When the wax is set the socket take about a yard of No. 20 copper-bronzehandles, as shown in the accompanyingshould be quite firm and making excellent is rather too brittle for this operation-windsketches. A length of good hard dry woodelectrical connection with the cell.Unless three turns round each end of the spreaderand a few screws and washers are all thatit is very roughly handled it will stay in position. soastobind down theendsoftheisrequired,thesketches being self-ex- stranded slings, but leaving the sling onplanatory.Smooth all edges off the wood When making up batterieswith the the other side of the spreader, as shownwith glasspaper and give it 'two or three" flash -lamp " type of battery as units the in the photograph (Fig. 3).These slingscoatsof shellac varnish, orit may beconnections from unit to unit are more should not make a much more acute angle, easily made with copper foil than with and may be less acute than that of an wire.Each unit should be separated from equilateral triangle-that is, G J and Ill the next by a sheet of waxed blotting should not be longer than G H.The ends paper, and the whole battery should be of the binding wire, after the three turns placed in a box with well -waxed bottom have been made, should be twisted to- and sides or stood on a sheet of glass. gether and passed through the eye of the For "plugging in " with batteries made bobbin insulator and brought back to of flash -lamp units nothing is better than and H, each single wire end being bound a spring tie -clip soldered to the end of the round twice again and finishedoffby lead from one'of the H.T. terminals of the twisting together. set. ERNEST LANGMEAD. The example shown by the photograph has been made with large cotton -covered wire so as to show how the spreader should be wired, and the loose ends sticking up at the right of the print are the free ends Winding of the binding wire after they have been twisted round the sling to prevent it rid- Inductances ing out of the notch.Two bobbin insula- tors are shown making a "shackle," which is quite a good way of making up aerial WHEN windinganinductanceor insulators. A double loop of wire is passed other coil some means of supporting round the grooves of the bobbins and then the full spool is necessary, and the illus- the bobbins are twisted in opposite direc- tration shows a simple method of effecting tions, so that the double loop is twisted this without fixing up a special frame or into a strand as shown, while the two free other spindle arrangement.Procure two endsarethen twisted over on topas hooks of the size and shape shown, and shown near the larger of the two bobbins. screw hook A in any wooden fixture.Do not screw it right home, but just so that Aerial Wire it can be turned either way without undue The aerial wire is passed through theFigs. 1 and 2.-Telephones Fitted with Handles.effort.Hold the spool in position almost eye of the second bobbin and the tail end touching the vertical portion of hook A. twisted round the straight run, so that nofinished in black enamel or in any otherThe position of hook 13 can nowbe marked twist is put into the run of the aerial wireway desired.Fig. x shows a back view ofon the wooden support, allowing only just. to weaken it.If stranded wireis usedthephone andlinkconnectedtothe for the aerials the wires may be unstrandedwooden handle by the screws and washers and then twisted one at a time round theA, and the side view and general arrange- straight run to make off. ment is clearly shown in Fig.. 2. The lead-in should be a continuation of 0. J. R. thestraight run of the aerial.Ifitis passed round a bobbin insulator and tied up tightly with a piece of string, this will avoid a joint and allow for subsequent High-tension alterationinlengthiffound necessary Simple Winding Devices. (Fig. 4). Battery Tips This bobbin necessarily makes the third enough of the horizontal part to enter the in the chain, being additional to the two0 spool and support it, say in.Screw in shown in the photograph, and would be THE socket connections of the ordinaryhook B level with A.Now if the two hooks better able to take the strain, as the aerial 36 -volt plug-in type of H.T. batteryare turned slightly backwards, the spool would thus have no sharp edges to bendsometimes come adrift from their solderedpushed overA,itwill be found quite over as it would if wired to the eye of theconnections to the cells.As they are em-easytoinsertB,asthereissufficient bobbin. GAMMA, bedded in wax they are somewhat difficult-clearance. MICJAR. (Intatcur Wird"5 670 DECEMBER 23, 1922 eeee uuuuu ozoomoocoseontaeco mmmmmmmm o mmmmm eeeeee...... D Rectification by Crystal The ConclusionoftheArticleon theTheoryofCrystalRectification

HAVING studied the rectification by a The most common type of potentiometerhalf -cycle rising to .3 volts causes a current crystal which obeys Ohm's law, weused for this purpose is shown in Fig. 5,of to plus 52 micro -amps (=62 micro -amps) will consider the manner in which rectifi-where the terminal D is joined to one sideto flow.The negative half -cycle rising to cation is obtainedby such a combinationof the crystal combination and terminal.3 volts causes a current of to minus 2.5 as that of the carborundum-steel, whichF to one terminal of the telephones.Themicro -amps (=7.5 micro -amps) to flow. does not obey Ohm's lay`. left-hand cellistrying to force .currentThe next positive alternation, or half -cycle, through the part A E of the resistance A Bproduces a current of to plus 43 micro - Carborundum Crystals through the outside circuit in the directionamps (=53 micro -amps), and the next Fig.3isa characteristiccurve of a ofFto D.The right-hand cell is trying tonegative alternation one ofto minus2 carborundum crystal.' The curve and theforce current through the outside circuit inmicro -amps, or 8 micro -amps, and so on.

100 MICRO - F.ig. 3.-Characterisic Curve AMPS 75 of a Carborundum Crystal without Auxiliary Voltage. 50

25 CURRENT RISING TO A MAXIMUM Of 2iNICRO-AMPS. 10

2 0 2 .6 .7 .8 1.0 1.2 TIME OF CURRENT I..-- PULSES

TIME OF ONE TRAIN Fig. 4.-Curve of Carl): run. OF OSCILLATIONS dum Crystal Using an Auxiliary Voltage.

oscillatingvoltagesplottedthereon are drawn in the same way as the characteristic The charges put in the telephone con- curve of the Ohm's -law crystal, with the denser will be, as before, the charges put oscillatory Voltages applied across it.It in during the positive half -cycle less those can be seen that unless the voltage applied F;g.6. - Receiver CircuitUsing put in during the negative half -cycles. is greater than .7volts only very .little Carborundum Crystal. The steady currentofto micro -amps current will flow in a positive direction; always causes a certain pull on the tele- and unless the voltage applied is less than phone diagram.Therefore the diaphragm 'minus.3voltsina negativedirection will be deflected by an amount propor- practically no current will flow, and even tional to the pull caused by that current after minus .3 volts only a very little flow. which is due to the difference between the Now the E.M.F. of the received oscilla- steady current of to micro-amps-as shown tions will never rise to as much as .7 volts, MAAAAAAARANVV a by the line s c on the graph, Fig. 4-and so unless some extra potentialis placed *1 the current a a a a, which is due to the com- across the crystal, rectification by a car- bined effects of the potentiometer voltage borundum crystalisof ,no practical use.Fig. -.-Diagram of Potentiometer and Battery. and that rectified by the crystal. This fact can be made clear by studyingthe direction of D to F and through the part Thus by means ofthepotentiometer the graph, Fig.3,of the characteristic E Bof the resistance. we have adjusted the crystal to its most curve of a carborundum crystal where there The resultant current Will be the difference between the two.If,sensitive point where the latter suddenly is no extra voltage across the crystal, the becomes unidirectionally conductive, and received oscillations being therefore plottedtherefore, the slider E is at the centre point of AB no current will flow.If A E is lesshave thus been able to rectify the oscil- on the curve at zero potential, with the latory potentials, picked up by the receiv- result that maximum rise in current-duethanE B.,Fwill be positive to D, and if A E is greater than E B, D will be positive toing aerialand transmitted by a spade tothe greatest half -cycleofoscillatory F. A detector circuit employing a potentio-transmitter by means of a carborundum voltage rising to .3 volts-is only2micro - crystal. C. F. N. R. amps. The extra voltageis .applied bymeter and battery is shown in Fig. 6. means of a potentiometer and battery. §upposing, then, we apply across the crystal a steady potential of .7 volts (see StageIllusions andEntertainments:T'lis is the The Potentiometer Fig. 4), so that each positive half -cycle of title of a new " Work " Handbook of special interest toallamateur entertainers. In the large variety The potentiometer enables one to applyan applied oscillatory E.M.F. acts in the ofsubjects includedare Stage Carpentry; Scene Painting;StageEffects;Making -up;Black Art; that voltage after which the current sud-same direction as the potentiometer volt- Making a Manikin Theatre; A Marionette Theatre; denly increases out of proportion with.theage, and each negative half -cycle acts in Making Ventriloquial Dolls; Illusions; Smoke, Rag it. and Sabd Pictures;Paper Manipulation; Making increase of voltage.In the case of theopposition to Now" the potentiometer and WorkingaPunch -and -Judy Show,etc.etc. crystal whose characteristic curve is drawnvoltage causes a steady flow of current of Price Is.6d. from all booksellers, orIs.8d., post paid, from Cassell & Co., Ltd., La Belle Sausage in Fig. 3, this value is .7 volts. to micro -al -rips,so that thefirst positive London, E.C.a. DECEMBER 23, 1922 671 (Imateur Iftrekss

IIII il i vs:

I

11 ill 1111111111 1liblitill N'ir- 0161 .0 -

lit li The Valve

Mr. " ORA " wishes his many friends and supporters a Happy Xmas and a very Prosperous New Year. He looks forward to spending many delightful hoursintheircompany duringthe festive season. For receiving vocal and instrumental items you must have

MULLARD "ORA" VALVES -"'

to get the best results. rt,

OscillatesRectifiesAmplifies. Specially recommended where good amplification is required. The " Ora" Valve requires about 3'8 volts on the filament and 30 volts or overbetween the anode and filament for efficient results. 1 5/-each

. The Mullard "R" Valve is now reduced in price from 22/6 to 17/6. mallardRadioValve 45,Nightingale Lane, Balham,S.W.12.

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Imo an- WirelEss 672 DECEMBER 23, 1922 IMPORTANT WE HAVE OPENED VERY COMMODIOUS PREMISES AT 54, Gracechurch Street, E.C.3 for the demonstration and saleofalltypes of Wireless Receiving Sets and " ClaritoneLoud Speakers. Amateurs and Experimenters will be able to obtain every part required for any type of Set including ; Transformers, L.F. and H.F Valves, M.O. and Mullards Headphones, alltypes, all resistances Brass W.O. and TelephonetypeTerminals, Condensers, variable and fixed, all capacities Nuts, Washers, Contact Studs and all other parts Vario-Couplcrs and Variometers Accumulators Coil -Holders and Cods Dry Batteries Anti -capacity Switches,all types Aerial Wire Rheostats, al types Insulators Radial Switches, 5, 10 and 15 way Heitzite and Galena Crystals Ebonite Valve Holders, Dials, Scales, other Cotton and other Tubings, all colours parts and in sheet Etc. etc. PRICE LISTON APPLICATION PETTIGREW & MERRIMAN, Ltd., 122.124, Tooley Street, London, E,C.1 Note: 54, Gracechurch Streetis a few minutes from Monument, Eastcheap, Bank, Cannon Street & London Bridge TELE. :HOP 134

o B NENEEIENENNIMININIMENINE1113111111161E 1!") Congratulationson a the Success of the For all wave tencrhs over 1000 ULTVWAVE AMPLIFIER (Made throughout by the Pete Scott Co.) For H.F. amplification above r,000 metres, you will find the Multi -wave Amplifier absolutely ideal. There is no tuning required: simply plug it into its socket and immediately you will begin to pick up Stations which have previously been out of your reach.Excellent telephony is being transmitted daily front Paris and Berlin and the Multi -wave will enable you to hear them with the greatest ease. Made in two stiles in solid ebonite throughout. NO., for use with one U.S.. Valve and No. z for Inure than In this litter, Mr. J. K. P. admits- that one stage of H.F. amplification Oa this case No. a is used as coupling between first and second H.F. Valves his Multi -wave does not work quite as and No. r between second H.F. Valve and Detector). well on The Hague wavelength as on the others.Every set has peculiarities of its No 1- Na 2-for own, and perhaps in this particular case, for use /6more than one12/6 wi,11 one stage of H F. for 1050 metres (the wavelength used for H.F. Valve amplification The Hague) transformer coupling is to be preferred.But for the Paris and Berlin Thinking of building your concertsthe Multi -wave stands alone '11 own Set?Send 6d. for a copy of " RADIO," which gives full . .its results are almost unbeliez.able. descriptions of home -constructed Radio Sets.Fully illustrated and well written.Thirty- two - page Cataloguefree with Booklet. FEATHERSTONE HOUSE, 64, HIGH HOLBORN, w.c.i. MARSHALL AD. 1110151EINENNEINEEEMEEIN 10111111110ElIS ME II mo.teur Wireless' DECEMBER 23, 1922 673 TeNteCeWireless.

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.._,.._ . 1 '--..-rs 99 A QS ier latariedi and give a Present, which is new and brings continuous enjoyment. T.M.C. offer you a complete range of wireless receivers from simple crystal receivers to cabinets -de -luxe.The illustration shows a T.M.0 Crystal Set No. 2 with patent Everset Crystal which needs no adjusting .:-., £5 :7 :6 each (Plus liZlisting) , T.M.C. Wireless Receivers give vocal, orchestral and dance music from the British Broadcasting and ensure ,!:-'it)11-11 A Merry Xmas. ,)( Call and choose your present to -day.1/ you cannot call, full particulars ,r,i.----.______--.Th,,/// will be sent on request. 1l clrr"-11,.14 The Telephone Manufacturing Co., Ltd. lia (i 68, NEWMAN STREET, W. 1 II c,' r------'-_,III/i 1 f------;--- 1 TeleAlton, 21.1useum 5581 We have engineers in every large town who install the wireless to your satisfaction. , .,-____,,,( NOW 1 LONDON, MANCHESTER & BIRMINGHAM AREBROADCASTING ; ., :_.,11 , ,7, ,,,,1 ..fl II

makesVreless worthwhile 1-

35 DECEMBER 23, 1922 enuthitrWirdess 674 1:11E]:111=11:AKI,Iiiihm.A1AAPIIILTJAWAliill_iiikhDEI 00lit*WrillEJO[1 111-tIN n'gE]gFgiD:10E/ gKI,E11:1*IgnggEXE11111:111CODE11. A Seasonable Gift which will be appreciated BUILD YOUR OWN SET FROM THE BEST MATERIALS OBTAINABLE

No finer Setcould be obtained if 20 times the price were paid.

Illustration shows :- Three Valve Detector -Amplifying Set, built up on the Unit system.

CONDENSER UNIT _BET u.Ton PANEL, L.F.A IIPLIFYING PANEL, I L.F.AsiPLIFYING PANEL, Usir No. I. UNIT No. II. I.Txtm No. H.

Condenser Unit. Detector Panel, Unit No. I. L.F.Amplifying Panel, Unit No.II. Handsome polished mahogany Cabinet. Handsome polished mahogany Cabinet. Handsome polished mahogany Cabinet. Panel ofbestqualityebonite,matt Panel of best quality ebonite, matt finish, bevelled edges.Valve holder.Fila- Panel of best quality ebonite, matt finish, finish, bevelled edges.Variable Con- ment resistance. 2 MullardCon- bevelled edges.Valve holder.Fila- Condenser Scale, ment resistance.Intervalve transformer denser '0005 mfds. densers, '0003 and '001 mfds. withknob, engraved. 8 Terminals. in iron case.Mullard Condenser '001. Mullard's Grid Leak. 11 Terminals. 10 Terminals. 12 Engraved tablets. 4 Engraved tablets. Coloured Systoflex, 12 Engraved tablets.Coloured Systo- Coloured Systoflex,copper wire and copper wire and BLUE PRINT. flex, copper wire and BLUE PRINT. BLUE PRINT. 37/6each 30/.each 50/-each

READ THIS TESTIMONIAL from WALLSEND-ON-TYNE 271 MILES from LONDON " With reference to the set of parts I bought from you a short while ago for building A SINGLE VALVE PANEL, allow me to tell you that it has proved a great success. Whilst listening -inthe other night,I could plainly hear telephony from 2 L 0 London. Please forward parts for a L.P. Amplifying Panel to add to your Detecting Panel . . SUCH A RESULT CAN ONLY BE MADE POSSIBLE BY USING THE VERY BEST COMPONENTS OF CORRECT VALUES. WE SUPPLY ONE QUALITY ONLY-THE BEST OBTAINABLE.Inferior qualities lead only to disappointment. SPECIAL OFFER OF EX -GOVT. SULLIVAN HEADPHONES. Absolutely New. Thousands Sold. Cannot be repeated. 120 Ohms, 12/6. 120 Ohms (complete with Transformer. value 25/-), 3O/-. 8,000 Ohms, 36/6. Best quality Cords, 3/6.Postage, registered, 1/- extra.

INI0141101.11 The City Accumulator Co.

79, MARK LANE, LONDON, E.C.3 I Wholesale andRetail Distributors for Messrs. BURNDEPT,Ltd.Same TradeDiscount Allowed as by Manufacturers. AGENTS Phones: AVENUE 1316, 91, 92, 93 and 9936. AGENTS London: H. V. ALBROW, 68, George Street, Baker N. Wales: SOUTH WALES WIRELESS INSTALLATION Street, W.1. Telegrams: "TYCHE FEN, LONDON. CO., LTD., 18, West Bude Street, Cardiff. Glos.:BRISTOL WIRELESS CO., 52, Cotham Bristol. Codes: A.B.C. (5th Edition) and LIEBER'S. N. Wales, Lanes., Ches. & THB " ALL. Leirsster WALTER Ron E, LTD., 96, Granby Street, BRITISH " WIRELESS MANUFACTURES CO., LTD , Leicester. 18, Vauxhall Road, Liverpool. ECOMIEJEAk.lYggg-gggli-E DECEMBER 23, 1922 675 ntateur Wireless

K/at/eoeeooke#t

AWireless Instrumental Christmas A MERRYlightlyofa sound wave superimposed couldn't be better." Transmissions r -t CHRISTMASupon it.As a matter of fact, the most Saying which I Christmas toallgoodandsimple of sound waves is really a verytouchedwood,to Harmonics Programmes true wireless men.complicated affair, consisting of dozens ofwit the painted May theirsignalsripplesofdifferentlengths and -ampli-mantelpiece. Blind -spots Luck ! never grow less ! tudes 'woven together like threads in aWithin an hour a skein.If you have ever seen photographsshort burnt out two VG' OJ * * of waves made by the human voice youexpensive valves. This is going, when you come to thinkwill realise what extraordinary compoundsThen something went wrong, and hours of ofit,to be one of the most wonderfulof different curves theyare. When aninvestigation have not yet disclosed what Christmases in the/history of the world.orchestra:of several performers 'is playing,it is.The performances of the set are now One can safely say that every availablethe microphone ,has to respond simultane-far from good, and it has suddenly become wireless receivingset will be inaction,ously to innumerable impulses of varyingpossessed of an evil spirit.I have just which means that the world over threestrengths,and,ofcourse,thereceiver,discoveredthatthat mantelpieceisnot or four millions of people will be listeningperhaps hundreds of miles away, must dowood at all, but marble painted over by in their own homes to greetings and musicthe same.That the stalloy or aluminiumsome Vandal in bygone days! sent out to them by distant stations.Itdisc of a loud speaker can become by turns is safe to prophesy that in the next fewa violin, a cornet, a human throat, or a * * * days the great army of British wirelesswhole bandofmusicalinstrumentsis Of course you have noticed how often enthusiastswillbelargelyaugmented.reallyoneofthemost perplexingofthe receiving set lets you down when you Every schoolboy home for the holidays willmodern miracles. have invited friends to come round and want oneChristmaspresent aboveall listentosomeparticularlydelectable others; andso,amidstfeverishexcite- * * * * concert !As a rule itis some silly little ment, new crystals and valveswillbe Many thanks to2 W D and 2 0 H forthing, such as a loose connection, which giving their maiden performances in allgiving me acall. Both transmissions,defies detection at the time but leaps to parts of the country.Paterfamilias willthough on small power, were excellent.the eyes in a moment when it's too late. readily fallin with little Tommy's sug-Neither, I believe, used more than 5 watts,On such occasionsthe wise mantests gestion that a wireless set is the one thingwhich shows how much can be done now-through half an hour before his guests needed to make life worth living, for alladays with a tiny expenditure of power.are due to arrive; he sees carefully that of us arc wondrous wishing to give a W D'sfirstcallwas unfortunatelyin-allconnections are tight,that the lead present with which we can play ourselves !terfered with badly by some condenserin is attached and that everything is above You remember the old story of the smallwangler in the neighbourhood, who pro-suspicion.He searches for and obtains boy who saved up to give his sire a clock-duced cat calls in the loud speaker thatclear,strongsignals. Hegreetshis work engine in order that he- might becould be heard in the next room.How- friends with a quiet smile of assurance- allowed to enjoy the performances of hisever, the second attempt was most satis-and then the accumulator "conks out." factory, theafter -mentioned disturber ofAt least that's what mine did last night own in peace? the peace being probably engaged in a * 2' * * Sunday afternoon nap.Few of those who * * * offend realise that they are interfering with There are rumours that the broadcasting What a pity it is that the harmonics of stationsare concoctingsomething veryothers.Most of the elementary books lead Christmaspro-beginners'tobelieve that unless the setLearfield and Northholt come in so badly specialinthe way of in some places on the broadcasting wave- grammes.Let us hope that we shall beactually howls no harm can be done; as treated to the playing of those excellenta matter of fact, many instruments, if theylengths.Northholt especially often inter- orchestras which we have heard from timeare oscillating at all, send out a 'hetero-feresseriouslywith2I. O's programme, to time. dyne wave thatisaudible two or threemaking itdifficultto keep the set from milesaway. Theonlysure'testforoscillating.The elimination of harmonics * * * oscillation is to touch the aerial terminalwill be one of the big wireless problems of Which instrument do you think comeswith a wet finger.Clicks, taps or popsthe future, for the ether will soon be so outbestinwirelesstransmissions ? I in the receiver as the finger makes andfullthatitwill be impossible to allow should plump for them in the followingbreaks its contact are a sure proof thatone station to occupy two wave -lengths at order :i,clarionet;2,'cello;3, banjo;your set is causing interference.I makethe same time. 4, violin;5,piano. The difficulty withno apology for returning to this old topic * * * * the piano, one imagines, is that the micro-for the sake of the new hands who will phone, wherever it is placed, must alwaysbe operatingsets ;forthefirsttimeat It would be interestingifreaders in he nearer to some strings than the others.'Christmas. Thereare even "hall-various parts of the country would report Hence certain partsof the registeraremarked " sets that will oscillate if badlyhow they receive the broadcasting stations Undulyemphasised,whilstothersarehandled. now in operation, for some curious freaks almost swamped. areoccurring. The Manchesterair * * a' * station, for example, comes in strongly in * * * va Superstitious ?No, of course not.NorHertfordshire,whilstthebroadcasting is is It is amazing that the microphone andam I.Still. . . . Anyhow, listen to this. station veryfaint. Birmingham the receiver can deal atallwith suchA new set had just been completed, and almostasstrongasMarconiHouse, complex wave forms as those set up byafter afewadjustmentswasgivingthough three times as far away.On the evena common chordofthreenotes.wonderful results."Absolutely perfect," southcoastManchesterisreceivedin When we are describing the way in whichquotb Itothe partner of my joys andseveral places much better than Birming- the carrier wave is modulated we speaksorrows;"if you'd paid Doo forititham. THERMION. Omateur WtreieSS 676 DECEMBER 23, 1922 The Wonderful Future of Wireless Prophecies of Many Applications of Wireless in the Service of Mankind

L.1

SOMETHING lessthanthirtyyearsin time of peril, wireless gear is gradually The general use of wireless as a means ago the idea of using ether waves fordisplacing the compass, the sextant, andof keeping in touch with land, previously signallingpurposes was a mere possi-the chronometer, and issubstituting forreferredtoinconnectionwithships, bility slowly taking shape in the minds ofthem a new -system of navigation. applies with particular force in the case of aircraft.Once the aviator has taken wing one or two leading physicists. Direction Finding 1900 heisinapeculiarly isolatedsituation By means of the radiogoniometer, orwithout the aid of his wireless set. In1900, Marconi's fourye6.rsafter wireless direction -finder, a ship at sea is In the war, aircraft wireless enabled the pioneer invention of the extended aerial,abletoascertainitspreciselocation. wireless telegraphic messages were being flying scout to send down to headquarters This may be done on board by analysingapromptreportofhisobservations. sent across one hundred miles of inter-the direction of the incoming signals from vening hadalsobeen When employed inco-operation with a space. Speech two or more coast beacon stations in turn,firing battery, the result of each shot could successfully transmitted over shorteror alternatively, by sending out a call frombe recorded from aloft, and the necessary ranges throughthesame medium. In his own wireless set, the ship's wirelessdirectionstransmittedtocorrectthe short, the new art of wireless communica-operator can obtain in reply precise de-gunner's aim when necessary. tion had beenestablishedonasoundtails of his bearings as determined by the Again the development of the double - ,practicalfooting and was preparingto loop aerials at the shore station. loop directionfinder enabled a pilotto enterinto commercial competition with Such a method is particularly useful innavigate his machine by taking readings the older wire and cable systems. foggy weather where the ordinarydiffi- from a ground beaconstation,andso Rapid Expansion culties of navigation are enormously in-facilitated long-distance flying at night. Since then the progressive expansion ofcreased. A highpercentageofseaThe armistice came at a time when a casualties arise from the prevailing dangerflight to Berlin and back had just been wireless has been without parallel in theof wreck or collision during fog, owing history of invention.Even at the present rendered feasible by the aid of wireless as to the difficulty of ascertaining the truean auxiliary means of aerial navigation. day we have merely opened up the fringeposition of the ship relatively to a dan- ofthesubject,andthepossibilitiesof gerous coast or a neighbouring vessel. In Aviation further development in the future appear A wireless direction -finding set provides In civil aviation, where the safety of the to be inexhaustible. machine its freight, both passengers Quite apart from the enormous growththe most reliable means at present known of meeting suchasituationwithcon- and cargo, is of primary importance, the in popularity that is bound to follow thefidence. provision of wireless' equipment has now introductionofbroadcasting,thenew In addition itis probable that particu-been rendered compulsory by legislation. principlesandapparatusutilisedandlarly dangerous coast lines will in futureAs previously stated, it affords the only re- developed by thewireless engineer are liable means of keeping the pilot in touch continually finding new and wider fieldsbe provided with a chain of automatic wireless`;beam"ordirectionaltrans-with his base for receiving essentialin- of utility. mitters to supplement the present light-structions either as to the route to be taken It would be impossible within the scopehouses and foghorns which are found inor as tothe weather conditions that he of the present article to deal with thesepracticetobealmostuseless,ifnotmay expect to meet ahead. innovations in any great detail, but itis proposed to indicate briefly some of theactuallymisleading,infoggy weather.Distant Control more important directions in which wire-The French Government actually installed The application of wireless methods to less is rapidly making itself indispensable.a series of "radiophares," as such auto-the automatic control or steering both of matic transmitters are called, around por-aircraft and ofshipsorsubmarinesis Applications tions of the coast of Brittany just beforealready well known.Many alternative In the first place, a broad division maythe outbreak of war. systems have been suggested.According be -madeintothoseapplications which to one method the steering gear is con- have a special value, (a) at sea, (b) in theLocational Uses In the case of submarines, the wirelesstrolled by means ofrelays _actuated by air, and (c) on land.In the second place, tunedcircuitsenergised through wave- it should be borne in mind that to a largeequipment is indispensable and has served many other purposes than the primary onelengthsofaparticularfrequency. In extent these special uses have been made another a two -anode valve is employed, possible by the internal development ofof receiving official instructions from the "-proper quarters."For example, one ofand the 'electron current is automatically two main factors :(i) the introduction of diverted to one or other of two separate the thermionic valve as a supersensitivethe secret applications of wireless during the war consisted in the use of what wascontrol circuits,according as a compass receiver and as the most convenient and re- needle deviates to one side or the other. liable generator of high -frequency oscilla-termed "leader gear," whereby a fairway tions yet discovered, and (2) the progressthrough a mined area was indicated byDivining thatis being made towards the ultimatelaying down along each border of the Turning to new developnients of general perfection of directional methods of trans-channel a cable fed by alternating current.application on land, we find wireless being mission and reception. The radiations from' these marginal cablesused as a method of prospecting or dis- were picked up by suitable receiving setscovering mineral deposits.In this connec- Marine Uses on board a submarine or ship and formedtion it may he mentioned that in a recent At sea, quite apart from its value as thea .safeguide by meansofwhich suchtest of the directional properties of a par- only possible means of keeping passengersvesselscould thread their way throughticularaerial,itwas discovered thata in constant touch with their business andwaters that meant sudden death for thepeculiar assymmetry in its radiation curve private affairs en route, and in additioncrew of an enemy craft.By means of thewas caused by the presence of a metal to the unique part it has played in savingsame device vessels can enter a port withdrainage pipe buried in an adjacent field. countless lives through the S.O.S. appealsafety in the thickest fog. (Continued on page 68o) DECEMBER 23, 1922 677 e Matta? WirelitS5

Charging Accumulators from Alternating -current Mains

NE ofthemanytroublesofthe(3) the rotary converter; (4) an alternating - Oamateur isgetting his accumulatorscurrent motor driving a D.C. generator. chargedsatisfactorily. Forthose who havedirect -currentelectric -lightmainsThe Electrolytic Rectifier the matter isfairlysimple.Itisonly This has two outstanding advantages necessary to connect the cells up with awhere a small current only is needed.It variable resistance and ammeter and leaveis easy and cheap to make and can be left on for any length of time; it makes no noise and requires no attention while in use.Ifzoo -volt mains are available a transformerorchokingcoilshould be obtained to reduce the voltage to a reason- able amount, say25. Most electrolytic Glass -cell 2 -volt Accumulator rectifiers will not work on high voltages, (E. G. Lind & Co.). but they are always satisfactory for any voltage below 4o.If a transformer is notare screwed to a hard -wood block, as shown available a choke coil .may be used, butin Fig.2. The wood must be soaked in it is not nearly so satisfactory, and suitableparaffin wax or painted with brunswick transformers are fairly cheap to buy now.black or shellac varnish, and two terminals Forchargingaccumulatorsupto 12 screwed in and connected to the plates. volts the secondary winding of the trans-This will complete the rectifier, and when former should give 25, as there is a certainplaced in series with a low -voltage source amount of resistance loss in the rectifierof alternating currentit will only allow itself.The type of rectifier described inthe current to flow in one direction. the following notes has been used for a If the voltage used is above 30 it may be Fig. 1.-ElectrolyticFig. 2.-Method ofconsiderable time by the writer with satis-necessarytotreat the aluminium plate Rectifier. Mounting Plates. factory results for charging a 12 -volt 20 -beforeitwill function properly.To do amp. hour accumulator battery. this it may be immersed for a few moments them untilthey are charged.This, of The container is a 2 -lb. glass jam jarin a strong and boiling solution of washing course, is very wasteful if there is only a6 in. high (see Fig. 1), and is filled within soda.This will render the surface matt. 4 -voltcelltocharge,as the remainingan inch of the top with a nearly saturatedFor lower voltages, however, the rectifier voltageislostintheresistance. Low - solutionof ammonium phosphate.Thewill always work as soon as it is put into voltage cells can be connected in seriespure salt, and not the commercial, shouldthe circuit.To preserve the lifeof the with the lights of the house without mak-be used, as it lasts very much longer andplates they should always be taken out of ing very much difference to the intensityjustifiesthe extracost.The writer hasthe solution when not in use, and if neces- of the latter, and provided the lights passexperimentedwithsodiumbicarbonate,sary scrubbed after each charge. enough current there is no trouble. sodiumphosphate,andborax(sodium The size of rectifier described above will To charge accumulators from alternat-biborate),butthe ammonium phosphatepass half an ampere without heating too ingcurrent mainsisquiteadifferenthas been found to give better results than much.It should not be overloaded, or the matter, however.There are four methodsany of these. solution will get too hot and eat away the which are suitable for the amateur to use, Two plates, one .of lead and the otherplate.Of course, with a charging current and these are by means of :(s) The electro-aluminium, each 5% in.by 1% in.and of only this amount it takes three days lytic rectifier; (2) the mechanical rectifier;about Ve in. thick, are required, and thesecontinuous running to charge a 4o ampere - hour battery, but this is not usually a dis-

TRANSFORMER LEAD ALUMINIUM

AC MAINS 25 VOLTS CELLS Fig. 3.-Diagram of Rectifier Connections. RESISTANCE advantage and will certainly not do the cells any harm.Two or more rectifiers might be connected in parallel if desired,/' but itis dolibtful whether this would be, better than using one of the other methods R.A.F. WIRELESS OFFICERS' REUNION DINNER. of charging available. Amongst the readers of "Amateur Wireless" there are certainly many thousands who during the war A diagram of connections for charging) served in the Royal Air Force.How many of these, we wonder, recognise any of the former officers accumulators from mains through a trans; shown in the photograph above ? former is shown in Fig. 3. J. Fl_S, emateur Wireless 678

EVERYONE knows the familiar words "Hullo,hullo,hullo,2 L 0,the LondonBroadcastingStationcalling," and most of us have tried at one time or another to imagine what sort of a place a " A.W's" Special big transmitting station must be. You can believe, therefore, how delighted I was when, the other day, the telephone brought an invitation to spend an evening at Mar- Representative coni House with Mr. A. R. Burrows, the announcer, who up till then had been ".a voice but nothing more." Visits

The Broadcasting Room The broadcasting room is on the seventh 2L® floor,butfortunatelythereisalift. Imagine a mixture of a large drawing - room, an office and a tent, and you have some idea of what 2 L 0 looks like.The furnitureconsistsofa grand piano,a the open top of the piano, and others are numberofcomfortablechairsfor. the at hand, adjustable to various heights. artisteswhoareawaitingtheirturns, music stands, a filing cabinet and a large The Change -over Switch desk.-The floor is covered with a thick, The change -overswitchseen onthe sound -deadening carpet, whilst walls and pedestal actuates a remote control in the ceiling are draped with hangings in order SENATORE GUGLIELMO MARCONI instrument room which throws into action G.C.V.O., LL.D., etc., to do away withthecuriousresonant the whole of the transmitting gear. At soundthataccompaniestransmissions of world renown, who made wireless broad- one side of the concert room is a bracket casting possible. from a room whose sides and top are bare. which containsatell -talelamp, whose Near the piano are the famous chimes, steady glow shows the announcer that the clearly seen in the photograph.They are transmitter is working.This bracket also The Chimes operated by Mr. L. Stanton Jefferies, the supports a pair of head phones connected As the clock nears the hour Mr. Jefferies accompanist, who puts real soul into the to a receiving set working on a small frame takes up his position at the chimes, whilst work !In the middle- of the room is a aerial in a distant part of the building. Mr. Burrows stands at the central micro- pedestal supporting the microphone which He is thus able to listen -in and can signal phone. "Quiet,please,"saysthean- is used by the announcer as well as by to a singer to come nearer to the micro- nouncer-a necessary warning, since others singers. A second microphone hangs from phone or to move farther away from it. in the room often do not realise that any- thing that they say may be heard even in Shetland !The long hand touches the hour; over goes the switch and the chimes ring out.Mr. Burrows gives the general call and announces the first item.Then theswitchisopened again whilst the first performerisgettingintoposition. " Ready ? "Singer and pianist nod ;the Hullo C Q,Amateu a ftiappry

little light on the wall bracket flashes on, and in a moment the first song is on its waytolistenersin, allpartsofthe country.

The Apparatus So much forthe concert room; and now for the apparatus.This is housed in a room some distance away and does the actual work of transmitting. Large notices outside the door give all and sundry warn- ing that the place is dangerous.When you realise that the secondary winding of the main transformergivesaworking potential of 22,50o volts you will see that 01r. L. Slanic7, 70e r,fs ,.1 . .C.`414 , Mr. "'oh" , Miss Oiit e Shiners. 6,1,1P such a warning iS not out of place. Transmissioif: Photographed in the BroadcastingRoomat 2 L 0. The transmitter (a photograph of this is 679 &taw -Wireless 0

high-tension lead is a "speech -choke " con- nected to a large inductance which varies the potential on the anode of the oscillator valve.Each variation iscarried to the A Broadcasting aerial and so helps to produce the com- plex ripple which, superimposed on the carrier wave, conveys every modulation of Station speech or music. The Modulator Panel The modulator panel has two valves, a at control and a sub -control.The plate of the firstis connected through a high re- sistance to the speech -choke, which is also Christmas connectedtothepositivehigh-tension lead. Its grid is joined through a con- denser to the anode of the second valve. When the microphone is spoken into, the varying resistance produced by the vibra- duce between them a direct current with a tion ofits diaphragm causes a variation "ripple "of boo persecond. Thisis totakeplaceinthecurrentflowing smoothed out by a double filtering system through the speech transformer. This pro- which actually makes the current more duces changes in the potential on the grid 111hhim... .,1001011111 eventhanthatsuppliedbyadirect - ofthesub -controlvalve,whichthen MR. ARTHUR R. BURROWS current generator.One can understand causes still larger variations on the grid 2 L O'S ANNOUNCER, now why 2 L O's transmission are so com- of the main -control valve.This in turn variesthe anodepotentialoftheam- to so many thousands just " a voice "-and a pletely free from humming. clear voice, too, The filaments of the valves of the three plifier, and so the speech rippleissuit- remaining panels are lit by a 40 -volt 330 - ably built up. ampere -hour accumulator.The drive os- My thanks are due to Mr. Burrows, who shown on the cover) consists of four panels. cillator receives its anode potential from was kindness itself,and to Mn R. H. That on the left is the rectifier, next come the rectifier,its grid being connected to White,M.I.E.E.,M.I.R.E., whoseex- the drive oscillator and the amplifier; on earth, which at 2 L 0 means the lead roof planations of the complex mechanism of the extreme right is the modulator. and the steel framework of the building. the transmitting set made everything clear Power comes from the ordinary supply The valve of the next panel is a trans- even to one who has had little practical mains, but a special arrangement is pro- mitter, whose grid potential is controlled, experience of the transmitting and broad- vided so that either of two entirely dif- by means of reaction coils, by both the casting side as distinct from the receiving ferent sets of mains can be utilised.It is drive and the amplifier.In the positive side of wireless. m BD.A. delivered in the basement of the building toa io-h.p. motor coupled directtoa 6 -kw. alternator which supplies current at 5oo volts.From the alternator a cable runs to the transmitting room at the top of the building, where it is connected to the primary of a 6 -kw. transformer, whose Wirelessspeaking: act secondary winding gives out theterrific voltage already mentioned. The Rectifying Panel The function of the rectifying panelis to convert alternating current to direct at a pressure of io,000 volts.The filaments ofitsvalves are lighted from a trans- former whose primary is connected to the main 5oo-volt alternating supply.Thus the filaments of these huge valves-they are as big as Rugby footballs-become the positive high-tension pole of the wireless circuit. Eachvalvedealswith 300 alternations a second, and as they are so arranged that each of them deals With one side of the alternating waves, they pro - Reception : A Typical Drawing -room Scene this Christmas. mateur Wtretess 680 DECEMBER 23, 1922 " THE WONDERFUL FUTURE OF WIRELESS " (continued from page 676), Similarly, in another set of experiments, a rubbish heap containing a number of empty tin cans and biscuit cases made its RADIOGRAMS presence felt in quite a decisive fashion. Subterranean Uses The application of wireless signalling toI T isstated that the Bar and Formby Thepremises of theCo-operative nines has shown that subterranean com- Lightships are to be placed in wireless -Wholesale SocietyinBlandfordStreet municationisperfectlyfeasible. Heretelephone communication with the Liver-havebeenselectedfortheNewcastle

again the new science will show its valuepool Dock Offices. broadcasting station.The aerial is to be of attachedtotheboiler -housechimney, intime asasaverofhuman life ai accident or emergency. 15o ft. high. Americaistohave a nationalradio

Television week.

The transmission of pictures over tele- Furtherinvestigationsoffadingare being carriedout by the Glasgow and graph wiresis a problem that has long It is stated that -the Cardiff broadcasting exercised the minds of inventors.Recent District Radio Club.Members situated in inventions go to show that a solution ofstation will be completed by Christmas. different parts of this locality are making the problem may be found by means of tests with the broadcastingstations wireless methods.The prospect of seeing Another amateur, Mr.J.Jardine,re-whereby a certain station is selected for a the latest cinema films broadcasted is cer-ports on hearing W J D, United States,particular night, and each member listens tainly attractive and will form a welcomeearly in the morning of Dec. 2. intotheentire programme. Detailed addition to the present fare of song and reports as to reception are prepared, and music. these are collated at the subsequent meet- The Attorney -General of New York Stateing of the club.Itis hoped to secure Wired Wireless has declared that marriages by wirelessvaluable data in this way. Wired wireless, as applied to existingare illegal. telephone lines, will enable more than a dozen independent conversationsto take Valves do not have to be/approved by place over a single pair of wires without The Japanese Government has decidedthe Postmaster -General for use under a theslightestinterferenceorconfusion.to assist in the proposed formation of abroadcast receiver licence; they must bear This will result in greatly reducing theJapanese -American Radio Corporation. thestampoftheBritishBroadcasting Company. cost of the existing telephone service, more In this connection it may be particularly in the case of long-distance stated that Muilard valves (used by the work, where the expense of laying down A song inEsperanto, sung by Misswinner of the fIrst Transatlantic test) are linesisat Gladys Cosmetto, was broadcast from 2 L 0stamped with the B.B.C. mark and can be and maintaining the trunk on Dec. S. present enormous. used freely for broadcast reception.

Valve Development Barnes District Council has refused per- Thedevelopmentofthethermionic Don't expect a special Christmas con- valve has resulted in a great extension ofmission to allow householders to fix aerialscert from Radiola, the French broadcast- to street trees. itsoriginal purpose.The valve is now ing station.Like the Scots, the French employed in practice for rectifying high - reserve their celebrations for New Year's power alternating current, as an automatic Schoolsfortrainingthe voicesof Eve, the Reveillonfestivitiesbeing controller for dynamos and motors, andsingersforbroadcasting weredeclaredamongst the gladdest of the year.There- as a regulator in electric power supply andnecessarybyProfessorFlemingatafore, though no announcement has been distribution circuits generally.It threatens,demonstration at Trafford Park on Dec. 16.made yet, we,may look for something even in fact, to replace the dynamo itself.A better than usualif we tuneto1,55o thermionic tube capable of developing zoo metres on the evening of Dec. 31. The new P.M.G. is opening up negotia- kw. is already in use, and the manufacture tions with the Marconi Co. with a view to of a t,000 -kw. tube has been reported from Directional wireless experiment tests on America. settling its long-standing claims with the Government. less than to metres ( !) will probably take

Power Supply place between London and Birmingham Finally itis possible that we may yet at Christmas time.Itisstated that the collect our electric power supply through The news that music broadcast fromsignals cannot be picked up by stations Newark, U.S.A., has been heard in Eng-lying more than half a mile or so off the an aerial system erected upon the domesticland occasions no surprise in the States. roof.The problem of distributing power direct line.It is not an easy business to by radiation through the ether appears atItis understood that all the items men-receive them in any case; still,it can be first sight to be impracticable on accounttioned have been verified except one. done by cunning work with a separate of the waste involved, but the further per- oscillatorcircuittunedtoprovidethe fection of a strictly directional system of The claims under Wireless Inventionsnecessary heterodyne. transmission may quite conceivably resultwere found to have been adjourned gener- in bringing this scheme within the limitsally when the second report of the Royal of practical application. D. A. Commission on awards to inventors was Wireless Catalogues are often mines of information, and in this respect we par- issued on Dec. 15. ticularly direct our readers' attention to a Notes on Oxy-acetylene Weldingis IN cataloguejustissued by the Economic an important feature in the current issue Work on the South African WirelessElectric, Limited, ofto, Fitzroy Square, of " Work " (3d.).Other articles include : stationisto be startedat once, as theLondon, W.I.It is primarily intended for " ImprovingaSpringLetter -balance,"agreement with the Marconi Company hasthe experimenter, to whom it makes a " A Handy Pair of Steps," " Silver Workbeen ratified by Parliament.This stationspecial appeal, for every requirement is forAmateurs,"" MakingToysfromwill be the biggest in the world, givingcateredfor,fromoddsandendsof Waste Tins." direct service practically to every country.material to complete apparatus. DECEMBER 23, 1922 681 makurWu -de -Ss OUR INFORMATION BUREAU Expert Replies to Readers' Questions.Hundreds of Replies are sent by Post. TOENSURE A PROMPT REPLY PLEASE OBSERVE THE FOLLOWING RULES Write distinctly, give all necessary details and keep to the point.Ask one Question at a time-never more than two.Send a Stamped and Addressed Envelope. Send the Coupon cut from page 682.

Units of Capacity amateurs report that they cannot get 2 M T Q. Can you tell me of a unit of capacity for in parts of Cheshire, but I have no difficulty calculation purposes in receiving sets which CORRESPONDENCE at all, using one rectifying and two L.F. eliminates the use of so many decimal figures. ® ^,..n"."..rwwwwwts.".""rs.n.n."-rs-Wnevalves. Decimal figures are often regarded as very small I may say that Paris and P C G G quantities and neglected.-F. C. (Windsor) 5998 Fading are excellent on five valves, so there is A. A unit of capacity which is invariably SIR.,-Attention was drawn in a recentnothing wrong with the set.Another of used for tuning receiving circuits by calculationnumber of your paper tothe excellentmy friends, about three miles away (Hoy - is the jar.One jar equals A-0- part of a micro - results obtained by amateurs in the Northlake), reports that he cannot get P C G G farad and the formula for calculating the wave- at all, but Paris is louder with him than length in metres is: C, when I, equalsof Scotland who, using comparatively few the inductance in micro -henries and C, thestagesofamplification,receivedclearwith me.Itseems strangethat these capacity in jars.-L. C. telephony from London and even Paris.stations should be so weak at these certain \.,%."."."..cs."."..,-..""/C) This seems to suggest that wireless im-spots;Ialsofailtoget Konigswuster- pulses tend to travel along the meridianhausen, yet in Liverpool he is quite clear Partsrather than across the lines of the terres-on one H.F., one rectifying, and one L.F. ImportedWireless trial magnetic force.It would be interest-valves.-I. A. (Wellington). LAST week, in the House of Commons,ing to know if any of your other readers MajorMcKenzie Wood askedthecan throw any further light on this sub- WWW.0 Postmaster -General what arrangements, ifject.-H. A. .B. (London, W.). any, had been made with theBroadcasting Company or the British Radio Apparatus Insulated Aerials CLUB DOINGS Manufacturers' Association fornotifying SIR,-Some correspondence took place a the electrical trades as to the admissibility few weeks ago in the pages of your journal Stoke-on-TrentWireless and Experimental Society. ofimported partsin wireless apparatuson the subject of insulated aerials, and the Hon. Sec.-F. T. JONES, 360, Cobridge Road, Hanley. approved for Post Office licence; whetherfollowing experience may be of interest to THE secretary will be pleased to forward particulars he was aware that leading British importyour readers.At a demonstration given houses who had hitherto sold parts to wire- Hackney and District Radio Society. bytheRadioSocietyofHighgate on Hon. Sec.-E. R. WALKER,. 48, Dag mar Road, E.8. less manufacturerswerefindingtheSaturday, Nov. 25, an indoor aerial was Os Dec. 7 a lecture on "Insulators and Insulating greatest difficulty in securing the informa- Materials" was given by Mr.Sandford. Inthe used,consistingof asinglelengthof courseofthelecture Mr. Sandford demonstrated tion necessary to guide them in consider- the insulatingqualitiesof various materials. and whether herubber -covered cable such as is used for ing forward contracts ; house -lightinginstallations. The aerial Burnham, Highbridge and District Wireless Society. would consider theissue of a detailed Hon. Sec.-L. Lor-r,52, High Street, Burnham -on - was 4o ft.long and ran parallel to and Sea. statement on the subject? 3 ft. away from the wall and 2ft. belowTHE secretary will be pleased to forward particulars Mr. N. Chamberlain, in reply, said that of the above society to persons interested. the receiving apparatus which might bethe steel girders supporting the roof.The earth connection was made to a rusty gas Fulham and Putney Radio Society. used under broadcast receivinglicences Hon.Sec.-J. WRIGHT DEWHURST, 52,North End bracket.It is evident from this that theRoad, West Kensington, W.14. would be limited to types submitted forconditions were not favourable for the re-ON Dec. 8 Mr. Calvet brought to the club -room a the approval of the Post Office by members very compact portablethree -valvesetfittedWith ception of signals, but amateur telephonyspecial low -frequency transformers, and the mem- of the Broadcasting Company and foundand other stations came in well on a single bers present had a very pleasant evening "listening to conform with certain technicalstan- in."The speech and music were very loud and valve, and three valves worked a loudclear and freefrom theusual disturbances,this dards.It would be a condition during a being due tothe designofthe transformers and period of two years that such apparatusspeaker sufficiently well to enable a hun- type ofcircuit used. must be made in this country, with thedred people todance to theorchestral music from 'Marconi House.-J.F.S. Chorleywood and District Wireless Society. exception of certain parts which for the Hon. Sec.-A. G.S.RICHARDS, Hillbrow, Haddon (Condon). Road, Chorleywood. present were confined to batteries, accu- THIS society meets every Monday evening, and all mulators andoutsideaerial equipment. interestedareinvitedtocommunicatewiththe These conditions had been announced by Reception in Cheshire secretary. his predecessor, but he would endeavour SIR,-In reading your issue of Nov. 25 Coventry and District Wireless Association. Inotice that Thermion asks for the ex-Hon. Sec.-H.II.THOMPSON,44,Northumberland tosecurepublicityfortheminthe Road, Coventry. periences of those living in Cheshire asPARTICULARS of the above society may be obtained technical press. regards reception.My station is situatedon application being made to the secretary. at Hewall-on-Dee inthe Wirral Penin- Stratford -on -Avon andDistrict Radio Society. " The Modern Boy's l ibraryis the titlesula;itis badly screened on the N.E. Hon. Sec.-E. W. KNIGHT, 17, Park Road, Stratford - on -Avon. of a new series announced for publicationand W., but not on the S.E. or S.W. THE secretary invites application for membership of this season by the House of Cassell.TheThe aeriallies north and south.As tothe above society. aim of the books, which are well and fullyreception,Ifailtoget Marconi House Manchester Wireless Society. illustrated,isto meet the needs of the(2 L 0) during the day, using five valves Hon.Sec.-Y. W.P. EVANS,2,Parkside Road. Princess Road, Manchester. many boys who are keen to obtain know-(two H.F. reactance coupling and two L.F.) Nov. z6.-After having dismantled the transmitting of things. Thefirst and he is very weak during the evening.set used the previous week for theTransatlantic ledge "useful" test,andsubstitutedA.C.forD.C.supply,the volumes, published at5s.net each, areA friend living about two and a half miles work ofinstallingthe transformers and rectifying valves was commenced on Saturday afternoon at "Something to Make," "The Outdoor Boy,"away at West Kirby gets him very loud,z p.m., and the first tests were made at 11.5o p.m.. "Hobbies," and "The Boy's Workshop,"using reactance and two L.F. valves, hiseverything working well.AtIa.m. the circuit was still being adjusted and tuned, but insufficient radia- and these will be followed by others. aerial being screened on the south.Sometion as reached to justify a call to I A W and 2 F IL entaitatt WinteS5 82 DECFMBER 23 1922 the two American stations with whom the society HornseyandDistrictWirelessSociety. were working.At 2 a.m. a maximum radiation of Hon. Sec.-H. DAVY, 134, Inderwick Road, Hornsey. about9amperes wasregistered,andafifteen INTENDING members should send stamped envelopes minutes'call was given, and repeated at3 a.m. fur particulars of membership to the secretary. SeveralAmericanamateurstationswereheard SAL.E! working, and a few references were made to our transmissions, which started the idea that we had Wireless Society cf Hull and District. Great Clearance Xmas Sale been heard.A special survey was undertaken with Hon.Sec.-H. NIGHTSCALES, 79, Balfour.Road, the idea of getting the utmost output at the 4 a.m. Holderness Road, Hull. of Wireless Instruments and Accessoriestransmissions, and a few preliminary trials showedAT a meeting of the above society on Dec. 11 Mr. a little improvement and the call was commenced,J. Nicholson gave a lecture on " The Construction but at two minutes past the hour the fuses were ofInductanceCoils." Thelecturergave much blown, and after examination it was found that the valuableinformationandmanyusefulhints tc 9 transformer supplying one of the rectifying valvesamateurs intent on making their own coils. wasshortingacrosstheprimarywinding. No spares being at hand, we made a desperate effort C)N."..n.n..n.n.rw,./WVC) to overcome the difficulty by putting 5,000 volts A.C. direct on to the plates of the power valves.This HAL method only gave a radiationof about3 amps., BROADCAST TELEPHONY A perusal of a few of the items below will 9how that but a call was made and a list of stations received unapproachable value and prices arelistbd. Pur- repeated. Afterlisteninginforanother hourit Some of these transmissionsare commercial chasers are advised to secure while stocks exist, as was decided to abandon the tests until the follow-or official.Wave -lengths and times are liable a rush will undoubtedly be experienced, and replace- ing week. ments at thefigures shownwill possible. to alteration without notice. not be Dec. 3.-The temporary arrangement of thecir- Another opportunitylikethiswillnever again be cuit,asusedattheTransatlantictransmitting London B.B.C. Station(2L0), 369 metres. presented. station forthetests on Sunday, Nov.23, was re- Daily, usually 7 p.m. to so p.m. placed on the znd inst. for a more efficient one by ManchesterB.B.C. Station(2Z Y),385 BRITISH HEADPHONES mounting thevalves,switches,meters,etc.on a 4,000 ohms. VeryLight. BeautifullyFinished. specially prepared panel about 8 ft. by 6 ft. erectedmetres.Daily, usually 6 p.m. to TO p.m. Stalloy Diaphragms.Complete with Cords.Adjust- on insulators.Owing to a slight error in the trans- BirminghamB.B.C.Station (2W P),425 able Earpieces. formeradjustmentofthepowervalvefilaments metres.Daily, usually 6 p.m. to to p.m. (Sold elsewhere almost exclusively at 35/-4 one valve was burnt out.Two members, however, Croydon (G E D), coo metres.Daily. went toadealer and obtained a spare,arriving 19/6 Postage 9d. back at 2.30 a.m.Meantime a test had been car- Writtie(2M T),400 metres. Tuesdays, Only 530 left. riedout on theone valve,resultinginexcellent 8 p.m. Every type of instrument and accessory from Mer-radiation, and this, coupled with the second, gave Eiffel Tower (FL),2,600 metres.Daily, curyCondensersto Double -Slider Tuners at ridicu-a fairly good output, which, by means ofa few lously low prices can be seenatour showroom. extra adjustments, was increased considerably, and 5.20 p.m. to 7 p.m. Space naturally precludes completelist. finally,at5,6 and 7a.m.,theset was worked .The Hague (P C G G), i,oS3 metres.Sun- atitsmaximumefficiencywiththematerialin das, 3 p.m.to 5 p.m. VARIABLE CONDENSERS: hand.The reception was very poor indeed owing D), 3,200 metres. Capacity. Parts. Assembled for to local conditions, with the result that only about Rome(I C Daily, to a.m. Complete Panel Mounting. threeAmericanamateurstations wereheard. Itonigswusterhausen(LP),2,80ometres. .051 619 11/9 SA Q 0 (N.Y.district)was heardcallingSian- Daily, 4 p.m.to 5.30 p.m. .0075 chester 5 M S. Daily, .0005 Amsterdam (P C A),z,800 metres. .0003 s.io p.m. .0002 East London Radio Society. Haren (0 P V H), goo metres.Daily, every Hon. Sec.-L. E. LUBBOCK, Lecture Hall, Woodstock Top and Bottom Circular Drilled Ebonite Road, Poplar, E.14 hour from 11.20 a.m. to 4.2o p.m. Plate,1/3extra.Vernier,3/- THE secretary will be very glad to hear from intend- Intervalve Transformers,Ratio 5toa,finest ing members. manufacture ... 11/9 RadioComponentsLtd.areissuing Crystal Sets from 15/- to £3 Radio Societyof Tavistook. their catalogue on the loose leaf principle, " Royal Phone "Loud Speakers,4,000 ohms lion.Sec.-A. E. GRAVES, 2, ParkwoodRoad, resistance,ebonitehorngivingclarityof Tavistock. and we have received copies of the sheets tone and freedom from distortion.Stock THE above society is in process of formation.Will 28/9 any gentlemen who are interestedinthescience already issued.These include rheostats, Aluminium Condenser Vanes,fixed and moving. kindly communicate with the secretary? 22/24gauge ...... each duo -lateral inductance coils, triplug Spacers,true to .00r.Small, doz.1id.;large, Wolverhampton and District Wireless Society. tuners,micro -tuners,intervalvetrans- - doz. . 12dd.. Ebonite Knobs,tapped 2 B.A., with brass nut- Hon. Sec.-J.A.H. DEVEY, 232,Great Brickkiln formers,accumulators,condenserand st quality, 4d.; znd quality 2d. Street, Wolverhampton. other component partsforwireless ap- Aerial Wire,7/22 hard drawn copper, in looft. Ox Nov. 28 the above society held several experi- lengths . 2/9 ments with regard tothe receptionof broadcastparatus. Valve Legs,with nuts and washers,1d.each; music.The experimentswere made on crystal and doz. 9d. valve sets, including an Armstrong super-regenera Two CoilHolders,solidebonite mounted on tive set, telephony and music being distinctly heard 4/8 with the use of a frame aerial and a loud speaker. Three CoilHolders,solidebonite, with long Dec. 6.-A short paper was given by Mr. G. W. ANNOUNCEMENTS armstoavoid. capacityeffects ... Jonesexplainingthe usefulnessof various home- made contrivances for the testing of sets and the .,aniateurWireless and Elestrks." Editedby CrystalDetectors,adjustableinevery way, obtaining of good results. P.emard E. Jones.Price Threepence.Published on turned brass on ebonite 2/9 Thursdaysand bearing the date of Saturdayimme Slider Rods, 12 -in.or 13 -in. square brass, diately following.It will be seat post free to any drilledbothends... Id. Mount Pleasant Radio Society. part oftheworld -3mouths,45.ed.; emonths. EngravedIvorineScales,0-18.o°,roundor Hon. Sec.-W.R. Ffezaigq, 156,Upton Park Road, Bsgd.; 12 months. 179.id.Postal Orders, Post 341. Forest Gate, E.7. Office Ordersor Cheques should bemade payable Filament Resistances, extraordinaryvalue, AT ameetingon Nov. 27 Mr. W. E. F. Corsham,to the Proprietors. Cassell & Co. Len. velvetaction 2/4 president,gave hisexperiencesincommunicating Switch Gamest Correspondence is to be brief and written Arms,completewithknob,collar, with American amateur stations.He statedthat enone sideof thepaper only.All sketches and washers, bush nuts, ,etc.1st quality,1/3; he found that the best signals were received during drawings to be onseparate sheets. 9d. storms overtheAtlantic. Americanstations,he Contributionsare always welcome, wilt be promptly Valve Holders,turned ebonite, complete with said, could be received on two valves.Mr. W. D., ccnsidered, and if used will nuts,1/..;and quality ... 8d. be paid for. Keillerlecturedonsimplereceivingsets. On Communications should be addressed, according to crystal Cups.Plain1c1.;one,two,or three Nov. 34 Mr.. W.A.J. Smith gave a demonstration screw ... 2d. with a Mark IIItuner lent by the vice-president,theirnature,to The Editor,The Advertisement I,.arge Terminals, complete with nut and washer Mr- W. Beaton. adanagerorThe Publisher, "Amateur Wirtless,". each Id. LaBelle Sauvage,London, l.C.4. ContactStuds, in. by 1-in., or in. byIin. complete with nut and washer. ...doz. rd. Leeds and DistrictAmateur WirelessSociety. Insulators,2 -in.reels- Hon.Sec.-D. E. PETTIGREW, 37, Mexborough td.each; white egg,3d.;green egg, Id.; Avenue, Chapeltown Road, Leeds. greenshell...... each 3d. Ar ageneral meeting on Nov..24Mr.F.C.F. Brass Nuts, 2, 3, 4, 5, 6 B.A., 20. doz. Washers, Phillips gave a lecture and demonstration relating doz.14d. to-" Burndept "apparatus. Heexplainedhow Ebonite Sheets, 3, A., 3, 3 lb. 3/3 efficientreception ofthe shorter waves, as used Fixed Condensers,any capacity...... each 1/3 for broadcasting and amateur experimentaltrans- Grid Leak and Condensers combined each 2/9 missions, May be obtained by using certain tuning Slider Plunger complete ... each 4d. arrangementsandCertainmodes of interval % e Hertzite,1/6. Bornite, Carborundum, Galena, coupling. As regards tuning,the use .ofloosely - etc. ... each ed. coupled circuits with variometer tuning was adv.. Screwed Brass Lengths,12 -in. 2 or4 B.A.each 3d. cated.For intervalve coupling ofH.F.valves, the Inductances, wound 22/24 enamelled wire, each 3/ - " reactance -capacity "couplinghasbeenproved Ordersunder 301-kindty remitample post- as the bestfor short wave work.Musidal selec-Querist's Coupon Available until age.Balance refunded if excess sent. tions and speeches by the hon. treasurer And hon SEND FOR FREE CATALOGUE secretarywiretransmittedwitha"Burndept " Saturdays Dec. 30, 1922 transmitter, using one wattof power and a frame Pe DISPATCHaerial erectedinanother building. TRADE 'ILT A T a BY RETURN §UPPLIEDnitiLd., Proposed Pattern, Ashfordand District Radio " All About the Valve " and " The' 12.ZICsre : 1ZEG1-33NT 1282 Club. Ideal Unit Receiving Set "-Owing to the 71, Beak Street, Regent Street, London,W.1Wirt all persons inthese districts who are inter- estedinwirelessplease communicate eitherwith special demands upon our space it 'has been BetwAen Piccadilly Circus and dtford Circus Mr.Nettleton,"St.Albans," Feltham, Middlesex, necessary to hold ov.r the instalments of 'Buses3, 6, 12 13, 15, 32, 51, 53, 59and pass or with Mr.II.G.. Moss, 48, HighSt., Feltham,. with a view to forming the above club? these 'two articles this week, DECEMBER23, 1922 683 emattur W65 BUY YOUR XMAS GIFTS NOW ! FURTHER GREAT REDUCTIONS IN PRICES ALLGOODS SENT POSTFREE `VI Headphones BEAVER Splendid Crystal Complete Set of Detector CONDENSER Mounted on Ebonite. PARTS

contains: Ebonite Top and Bottom Plates, Machined Aluminium Moving Plates Aluminium Fixed Plates I Square Centre Spindle POST 4.3 9 3 Stay Rods, screwed both ends FREE Large Spacing Collars Small Spacing Collars High-classFilamentResistances4/ - Bronze Coil Spring 100 ft. Aerial Wire 7/22 Stranded H.D. Copper-the best 4000 ohms total EboniteKnob,drilledand screwfitted 3/10 B es tQ uality Swit charms 1 /6 Resistance. Brass Nuts forCentre Spindle Double Headband. Small Nuts Valve Holders

Guaranteed highly efficient. '0005 MF. 8/6 Best Quality Ebonite... 1/6 Complete with Cords.Ball '00075 MF.._ 9/6 Best Insulating Composition 10d. andsocketjoints ;highly 11/6 Condensers '0002 1/6 '001 MF. polished nickel cases ;best '003...... 2/9 Tungsten steel magnets. 0015 MF. 13/ - Chemically engraved Scales 0-180°, 31d. BEAVER COMPLETE CRYSTAL SETS Beaver " MIDGET " Crystal Set No. 5 De Luxe Set illwamoween

.1eeli11011881118818111188111r811111a8lliiiiiiinirMi nsinisismanansussessasiii 1 ismisiumuseasj

I181 111881119118111111

The Ideal Xmas Present.Length (it in. X 4 in.Absolutely guaranteed.15/- ;complete with 4000 ohm ear -piece, 30/-. Comprises Inductance Coil 9" X 31-", with waxed interior to prevent sweating, wound 24 -Standard Wire Gauge, Bronzed Wire, heavily No. 1 unassembled 15/- No. 2 unassembled 20/ - shellaced and varnished. Beaver de Luxe Crystal Detector with Crystal, Highly efficient Blocking Condenser, 2 Brass Rods, Special No. 3 assembled 241- ready for use pattern Slider and Plunger, concealed Insulated Wiring, all necessary Complete with Splendid Tested and Guaranteed 4000 ohm Terminals and Tabs, the whole mounted on polished Mahogany base, Phones, 45/ - with fluted edges. A Highly Efficient and Guaranteed Set. Assembled 50/- ready for use No; 4 unassembled 30/ - Complete with Splendid Tested and Guaranteed 4000 ohm Complete withSplendid Tested Guaranteed 4000 Phones, 70/ - Phones, 50/ - (Passed by Postmaster -General. G.P.O. Regd. No. 198) BEAVER ELECTRICAL SUPPLY CO. Telephone: GERRARD 1900. 109, REGENT STREET, LONDON, W.1. Special Terms to Trade.All Cheques and Postal Orders to be crossed London Joint City and Midland Bank. BEAR em tow r Wtreless 684 DECEMBER 23, 022 1211111111111111111111111111111111111111111111111/1111011111111111111111111111111111111111111111MMINA. MUNDAY, LTD., 59, WATLING ST., E.C.4 :: 45, EASTCHEAP, E.C.3 Wireless Receivers (One tour Queen Victoria Street, :: TELEPHONE: LATY 2972) CONTACT STUDS.. ... per doz. 5i BRITISH AERIAL WIRE, 7/22 Stranded Copper, 100 ft. 2/9 CRYSTAL DETECTORS ...each 2/5 MADE FILAMENT RESISTANCE ...... each 2/6 SWITCH ARMS 10d an1/ - HEAD- BROWN'S 4,000 OHM PHONES 30/ - BEST FRENCH 4,000 OHM PHONES 20/-

22/6 PHONES\ PP ,, 8,000 Leather LOW FREQUENCY TRANSFORMERS 12/6 Covered- IIIIIMIMMINME1111111111111MIIM1111111110111111M111111111111 of the Highest Efficiency. 4,000 ohm pair, Wireless is attracting all men.The Amateur is entering only the field in great numbers, and he wants to know all 25/6 about it.He will require Materials, Parts, Tools.He Postage gd. will also want to sell surplus material. Approved by P.M.G. and bearing B.B.C. " stamp. " AMATEUR WIRELESS is out to cater for this eta's of reader, who will be eager Also single .1,000 ohmPhones, with flex for knowledge and bargains.To meet h'm, use the Sale

and handle holder 12/6 each --postage extra and Exchange columns, which he is sure to search. Rate 3s.minimum, prepaid, Latest date DEPT. A.W. 2, 3d. per word, Friday mornings. Address THE CITY WIRELESS & ELECTRICAL DEPOT, The Advertisement Manager, "Amateur Wireless," 17, HATTON GARDEN, E.C.1. La Belle Sauvage, Ludgate Hill, London, F.C.4,

WILTON Wireless Outfits and Parts 0 k 010® '132A11,14 All Sets Approved by P.M.G. Members of the British Broadcasting Co., Ltd. P,71715,, WILTON No.1 OUTFIT- WILTON No2 OUTFIT- Ililid11111111:1'i4,111161 CabinetCrystalReceiver, Cabinet Valve Receiver, tapped Htifaitissi Hertzite Detector, 4.00oohm Inductance,el 000 ohm Phones, Phones, Aerial Wire, Insulators, Valve, H.T.Battery, Accuma- 111 etc. £3 2 6 lator, Aerial Fittings, Instruc- Plus B.B.C. royalties 7 6 tions.Designed by experts for Telephony Price £6 17 6 tanding a one £3 10 0 Plus B.B C. and Marconi royalties 1 12 6 L.F.TntervalveTrans- £8 10 0 formers ...... 15 0 Kr%BroadcastTrans- " WIRELESS VALVES formers ...... 3 6 Skeleton Variable Condensers Set of 7 Basket Coils ...4 6 '0003 '0005 '0of Grid Leak and Condenser2 6 81- 10/- 16/6 SIMPLY EXPLAINED " Fixed Condensers .00T,'0022 6 Switch Arms laminated ...2 0 Loud Speakers, z000 ohms 45 0 Velvet Filament Rheostats3 0 By JOHN SCOTT-TAGGART, F.Inst.P. 3 Coil Holders ... 10 6 Note Magnifier-Set of Parts HOneycomb Coils 1'3, 1;'92 6 Whether you buy a complete receiving to make yourself, designed on Tapped Inductance Coils, the" Radiocamo "principle, 300-900 metres, 9 tap- set or design it yourself, this book at 2/6 loud signals when attached to pings ...... 7 6 will save you time, trouble and money. any make of receiver,Exceed- Ivorine Scales ...... 0 8 ingly easy to make.Complete Engraved Dial and Knob 2 6 GET iT TO -NIGHT AS YOU GO HOME with Cabinet and Instructions,.Enclosed Detectors, Ball £1 17 6 Action, Hertzite Crys- Obtainable from all newsagents and bookstalls, Making a 3 -guinea Instrument. 4 9 or send us P.O. for 2/8 and your copy will reach you in two days. Get our 14 -page List. Trade Supplied. (Devereux Buildings, WILTON WIRELESS CO., LTD., Strand, 120 -124, HIGH ST., TOOTING, S.W.17. ntoin prtEit 7-wtb4London, W.C.2. Phone-STREATHAM533. DECEMBER 23, 1922 685 emat'Vel"5 A BALD STATEMENT 66 - The NEW p...)

Earth -Screened VARIABLE CONDENSER Range from '0001to'001mfd. Costs only 149Post Free.

Measures 3 in. x 31 in. x 1 in.only. Is Now Available from Stock. Is made and guaranteed for 12 months by THE RADIO COMMUNICATION CO., LTD. Direct from 34, NORFOLK STREET, LONDON, W.C.2. Or at NEWCASTLE: 17,Sandbill, LIVERPOOL: 67, Dale St. CARDIFF: Atlas Chambers, James St. Branches : SOUTHAMPTON: 19, Queen's Terrace. GLASGOW :so, Blythswood Square.

THAT MAKES YOU THINK--E.P.S. 38 POPULAR 2 VALVE RECEIVER RADIO FOR 45j- P.O. Regd. No. 2011 CONSTRUCT IT YOURSELF I COMPLETE SET FORWIRELESS MUSIC NO COIL WINDING TO DO i..1.11.111111.,11,11I11...11.111, 11.11.1 Polished Cabinet,DrilledEbonite 'Top, Double Phones, amciout.Detector and Terminals, Hertzite Crystal,=01. Aerial andInsulators, with Best Quality Phones.... This is sure to Price exclud- ELEC. SERVICE. I2a, KIRKDALE, S.E.26 please you. ingvalue Cheques and P.O.'s crossed BARCLAYS BANK £9

BRITISH BROADCASTING So simple that Fullstation BU "TER': achild can price CRYSTAL RECEIVERS FOR WIRELESS TELEPHONY, ETC. operate it. 14 : 10 : 0 A RELIABLE INSTRUMENT Dimensions AT A LOW FIGURE 61 X 6i X 51 111 , "11,111111.11.11 DoubleSlide TuningCoil, Spring Contact Crystal Detec- Approximate tor, Engraved Ebonite Panel, Weight 3 lb. Lacquered Terminals, the Send for our full list whole fittedintosolid, well T. H. ISTED, RADIO WORKS, TERLING, ESSEX Approved by Post- seasoned, polished mahogany master -General. Cabinet, AS ILLUSTRATION Approximate range 3,000 metres GENTS'- - £2 - 76 F?,SRI:E IF FITTED WITH VARIABLE CONDENSER MAKE FITMENTS Approximate range 3,000 metres I11111111111111111111111111111111111111111 IM1111MIIIIII1111111111111 £2 - 15 - 0 PTRIE Overseas Postage Extra. Send for our sundries pamphlet, make use of our stocks, ask us All that is necessary with these sets is to connect up the aerial and earth and toquoteforyourwholesale telephones and with small adjustment requirements :: signals should be received. EXTRAS.Doubloreleiohone Head 111111111111111111111111111111111111111111111111111111111411111111111111 Gear, Insulators Aerial and Earth ?Vire. GENT & CO LTD., ILLUSTRATED LIST POST FREE 4d. H. D. BUTLER & COMPANY, LIMITED, Radio Dept.,,Faraday.Works, LEICESTER L.F. Transformer London 25, Victoria St., S.W., Office: BANK BUILDINGS, 222, GT. DOVER ST., S.E.1. Works: CANONBURY, LONDON, N.I. Newcastie-on-Tyne: " Tangent House,' Plackett St. (05Fosi, Eon, be, Station) Price_ 22/6 each "4111=11111.11111111 ernatzur Wtrvigss 686 DECEMBER 23. 1922

This is to announce that on JAN. 15th RADIO PRESS LTD., the well-known publishers ofauthoritative wirelessbooks,will publish a new monthly wireless Magazine entitled : MODERN WIRELESS 11- NETT Every reader of "Amateur Wireless" should obtain the brilliant first number. The Magazine is edited by John Scott -Taggart,F.Inst.P., assisted by E. Redpath, Author of Cassell's " Work" Handbook " Wireless Telegraphy and Telephony," and by Paul D. Tyers, Author of "Construction of Wireless Receiving Apparatus," both well-known contributors to the pages of "Amateur Wireless." Order your copy from your newsagent, bookseller, from a railway bookstall, or direct (r/3 post free) from 1Rabio pro5 ,DEVER EUX BUILDINGS. STRAND, LONDON. W.C.2.

T-*

1111111 °I` 1181115

Top and Bottom CONDENSER BUSHES 9d. per doz.

ij kktklm\-*\\0\--0191))))))) SLIDER VALVE LEG KNOBS TERMINALS at1/3 per doz. ed. each No. 1 FILAMENT RESISTANCES 1 /9 Per doz. forPanel.Mounting, 3/6 SEND FOR OUR Hr. SPECIAL SPACERS WIRELESS guaranteed within LIST limits of '001 COIL PLUGS AND SWITCH LARGE POST ARMS 3/- per gross SOCKETS FREE 1 6 each SMALL doz. pairs 2/- per gross 1 /9 per ORMOND ENGINEERING CO., 199, Pentonville Rd., N.1 Telegrams :" ORMONDENGI, KINCROSS." Telephone :HOLBORN 1812. DECEMBER 23, 1922 6S7 Ontateur Wes It Speaks for itself and in no uncertain voice

THE WORLD'S STANDARD LOUD SPEAKER

AMPLIoN WIRELESS At Prices LOUD SOUNDING ranging from RECEIVERS E2 : 10 : 0 are supplied in to a series of £15 : 15 : 0 Ten Models Suitable for DAILY every service: DEMONSTRATIONS at the GRAHAM The Home, SHOWROOMS The ALGRAPHONE Laboratory SALON and the 25-26, Savile Row, Regent Street, W.1 Concert Hall 'Phone: Regent 1075 " MUSIC MASTER" HORN Type AR 13, 120 ohms £6: 0 : 0 Type AR 15, 2,000 ohms ... £6: 2: 6

" Graham" Wireless Pro- Patentees and Manufacturers : SCOTLAND: ductions include " High Mr. F. M. Milligan, Efficiency"Telephone 25, Renfrew Street, Headsetsofimproved ALFRED GRAHAM design and construction. GLASGOW. The " Graham "isthe AND COMPANY best Head Gear money St. Andrew's Works, Crofton Park IRELAND : can buy. Mr. Alex. R. Munday, LONDON - S.E.4 41, ChichesterSt., Full particulars forwarded ut on 'Phone: Sydenham 952. 'GramsNavalhada, Brook, London request."Lk for Folder A. IV. BEL FAST, emokur Wireless 688 DECEMBER 23, 1922 wooyErliogoomooKDELIEom00000ggio.K.00googoom000Kio*ocoK-Joo*ogoog0000mpoop HULLO EVERYBODY! Lai Do YOU Know US ? If not, why not ? We do not offer you " something for nothing," nor is this advertisement a catchpenny one. Goods supplied are value for money, both as to quality and price, We leave our customers to be the best judges.'Nuff said! Complete Sets of PARTS for Making Variable Condensers REVISED PRICES, without Ebonite EVERYTHING READY TO ASSEMBLE and A pprox. CONSISTS of the FOLLOWING : Capacity in No. o Plates Price Accurate Aluminium Fixed and Moving Vanes, Large and Small Spacer Washers, Centre Microfarads Square Spindle (Screwed Ends, 2 B.A.), 3 Side Rods, 12 Nuts and 12 Brass Washers '0015 85 9/- (2 B.A.), Pointer -scale 0-180, Terminals, 3 Bushes, Spring Coil Washers, Best Quality '001 57 6/6 Knob with z B.A. Nut in Centre. ALL HIGHEST QUALITY GOODS. '00075.., 43 5/6 '0005... 29 4/6 PLEASE NOTE '0003 ... 19 3/- - . 0002 13 2/3 DRILLED EBONITE ENDS 11- per pair extra ' 0001 ... 7 2/ - Postage and Packing, 11- per set extra.Two Sets, 1/3.Three Sets, 1/6. Owing to the extraordinary value given in above Condenser Sets, we are compelled to make these charges Vernier ... 3 119 for packing,. postage, etc.

ALL the following GOODS POST FREEat the SPECIAL PRICES attached for POST ORDERS Jf you are not satisfied wit6 value, return goods and we will refund all e6arges Filament Resistances.Most wonderful value in Aerial Wire, 7/22 bare copper, stranded,first Interyalve Transformers (low frequency), high the wireless trade.Each 2/6 and 3/6. By class quality, not a substitute.Price per class, tested, and guaranteed 5-1, 14/- each. Post. 3/- and 4/-. 100 ft.,2110. By post, 3/10. By 15/-. Smaller size, 10/6; by post, Switch Arms, with polished knob, bushed 2 BA Reel Insulators, 1d. each.Cannot be sent by 11/6.post, nut,laminated blade,springcoil washer, post. Hertzite Crystal, per piece, according to size, nuts and bush, 1/., 1/6,2/. each.By post, 1i mm. Insulating Sleeving, 6 yds. for 2/2.By 1/3 and 1/6.Cannot send by post. 1/3, 1/9,2/-. post, 2/6.12 yds. for 4/..By post, 4/6. Crystal Detectors on Ebonite.Simply marvel- Slider and Plunger, 5d.By post, 7d. EboniteDials, with engraved scale0-180,11 - lous value.Each 2/6.By post, 3/-.Also Slider Knob, plunger and 13in.rod.The lot, each.By post, 1/6. 3/3; by post, 3/9. 8d. Cannot be sent by post. Egg Insulators, 4for 9d.;2/-per doz.Not Fixed Condensers, withterminals on ebonite, Aluminium Vanes, 2 doz. V-.By post, 1/6.5/ - sent by post. .0003,.0003,.001,.002,.003,1/6;bypost, gross; by post, 61-. GridLeak and Condenser, .0003,very high 1/9;004, 1/9; by post, 2s. War OfficePattern Terminals, complete with quality and appearance, 3/9.By post, 4/3. Oojah Basket Coils,7in set, 5/- set.By post, nut and washer, 1/8 doz.By post, 2/2 doz. 5/6. Inductance Coils Wound Enamel Wire, 12 by Lead-in Tubes, ebonite, brass ends, 9 in., 1/2. Splendid Linein5 -piece Terminals, complete 4, 3/,Not sent by post. By post1/6. 12 in., 1/4.By post, 1/8. with nut washer, good size, 1/- doz. By Filament Resistance, " Thor" pattern, suitable 116. GoodCondenserKnobs,tapped 2B.A.,at for one, two or three valvesets,4/..By 2/-doz.By post,2/6. Large Spacer Washers, 3 doz. 9d.By post, 1/.. post, 4/6. Knobs, with brass nut (2 B.A.) in centre, high- Small Spacer Washers, 6 doz. 1/-.By post, 1/4. Terminals, telephone, highly finished, with nut class quality, 40. each.By post, 7d.6 for Terminals(verylarge),magnificentquality, and washer, 2/- doz.By .post, 2/6. 2/..By post,2/6. aerial and earth, complete with 2 nuts and WarOfficePattern Terminals,extraspecial CrystalDetector,cupenclosedwithglass 2 washers (2 B.A.stems), 2 for 8d. By quality,osv6.with nut and washer, 2/. doz. cover, dust proof, 4/6.By post, 5/3. post, 1,f, By

WE BEATCREATION ON PRICES ANDQUALITY.

HEADPHONES. wedon'tselle6eap and nasty telep6,mes. Genuine " Brunet " French Telephones, most Single Receivers (French) with cord,2,000 sensitive obtainable, 6 Tungsten poles in each earpiece.4,000 01 ms ohms ... 9/- (post I- extra) with cords (Double Receivers) 25:- post free French Receivers, 8,000 ohms, double receivers High Class British Receivers, double, complete with cords 25,'- post free with cords and headband...... 2 1 /- to 25/- (post 1/- extra) El Ca] To Callers :We Sell All Component Parts CHEAP!

Brass Rods, Nuts, Washers, Screws, Valve Sockets, Valve Pins, Stop Pins at wholesale prices. NOTE ! My terms are strictly cash with order.All orders by post are dispatched at the earliest possible moment, as we have great pressure just now on the postal department. IMPORTANT !The postal department will be closed December 25, 26 & 27th.

27, LISLE STREET, M. RAYMOND, W.C.2. RIGHT OPPOSITE 'Phone: Gerrard To avoid mistakes, this address is closeto DALY'S GALLERY DOOR. 4637 Charing X Road and Leicester Square Tube. ne 1711=1EAWYCE11:11Cgmj.i.imog000Kigooggclow000mEI:m00000000000: DECEMBER 23, 1922 689 emateurwirdess

THE BROWN'S .,.4, 11111111111MIt v--6-"-- itI11 MECCA.NO hid*"'''' MECCANO .64.9'00_ 17 RADIO Receiving Set ii; 111A0'.- - VIA , for Broadcasting and Morse Reception HEADPHONES THE Meccano Crystal Receiving Set has been thoroughly tested and has received BRITISH with great clearness, broadcast music and AND BEST speech up to 30 miles of London, Birming- THE FINEST ham and Manchester. HEADPHONES EACH SET IS TESTED AND GUARANTEED PROCURABLE for EFhICIENT ON A P.M.G. AERIAL An ideal present for Christmas. 30/- Give one to your boy and make him This price is for one pair happy. It is low in cost and complete of either 120 or 4000 ohm initself,ready to be phones, including cords connected to any aerial. - of good quality. - Send for this Book Catalogue, post free, gives Our new booklet, The you details of our Wireless Meccano Crystal Receiving Set, explains Radio so that every- Headphones, Loud one is able to understand Speakers, and Amplifiers Type FFeatherweight."Actual how simple is the reception weight, including cords, is 6 oz. only. of broadcasting, telephony Start Radio and Morse messages.This Obtainable from all Wireless Dealers booklet will be mailed free Now in an Efficient Way on request. PRICES and Inexpensive Meccano Crystal Receiving Set,complete, price155/- S. G. BROWN, LTD. ,, Aerial Set(including antenna, lead-

in and aerial wires and insulators) 12/6 19, MORTIMER STREET, LONDON, W.1 MECCANO Ltd Binns Road LIVERPOOL Head Office and Works :Victoria Road, North Acton, W.3

I BROADCASTING RECEPTION SETS One -Valve Set Complete for Working, £7 10s. 'SHUN Passed for DESCRIPTION : Broadcasting Single Valve, mounted on polished MARK TIME before you spend your money Licence G.P.O. I -in. Ebonite Panel with Variable No. 1038. on expensive wireless sets. Look at these Condenser,smooth prices and see what you save. actingresistance, grid Average range leak and Condenser and in miles for telephony. allterminalsclearly Crystal Sets ... 12/6, 30/-and60/-. SEND FOR engraved inwhite, in Single Valve Sets 50 CATALOGUE a Mahogany Polished Two Valve Sets 1 detector, 1 L.P. 50 RA 86 100 00 Cabinet 9 in. by 5 in. Two Valve Sets ...1 H.F., 1 detector 150 10 0 by 5 in. £3 15 0 Three Valve Sets ...1 detector, 2L.P...... 50 £11 5 0 A TAPPED COIL Three Valve Sets ...1 H.F., 1 detector, 1 L.F. 150 £12 150 for wave -lengths up to Three Valve Sets 2 11.F., 1 detector ... 450 AU 60 goo metres with 2 ter- Four Valve Sets ... 1 detector, 3 L.F. 50 £14 10 0 minals for coils for any Four Valve Sets ... 2 H.F., 1 detector, 2 L.P. 150 £16 0 0 higherwave - lengths. Four Valve Sets ... 2 11.F., 1 detector, 1 L.F. 450 £1710 0 The coilis enclosed and the tappings are brought out to an Four Valve Sets ... 8 11.F., 1 detector...... 1350 £19 0 0 8 -way switch mounted in the front of the cabinet. Five Valve Sets ... 1 detector, 4 L.F. 50 £18 100 Five Valve Sets ...1 H.F., I detector, 3 L.F. 150 £20 00 ACCESSORIES INCLUDED: Five Valve Sets ...2 11.F., 1 detector, 2 L.F. 450 £21 100 Five Valve Sets 1350 £23 00 Siemens' 54 -volt high-tension Battery with plugs ... 3 H.F., 1 detector, 1 L.F. for altering the voltage 150 Five Valve Seta 4 H.F., 1 detector ... 4050 £24 100 4 -volt 50 -amp. -hour low-tension Accumulator in The above sets are complete with valves, phones, case with carrying strap 140 accumulator, H.T. battery, aerial and insulators. They One pair of Sensitive Head Phones of 4,000 ohms are built with sloping panel and have a finish as good resistance... 110 as sets costing three times as much. Every set is guar- One Detecting Valve ... 150 anteed and sent on approval for four days against cash. We have a practical wireless experience cf fifteen years at your service. Total£7100 Write for our list, zar., it will save you pounds. Satisfaction Guaranteed or Money Refunded, SPECIAL TERMS TO THE TRADE WIRELESS INSTALLATIONS Ltd. 15, Aldersgate St., London, E.C. SIMPOLIA WIRELESS COY. AGENTS WANTED. (Dept. A), 170, West Green Road, Tottenham, N.15

ti entateur Winless 690 DECEMBER 23, 1922 PREPAID ADVERTISEMENTS. The THE MARK OF RELIABILITY The Latest Invention.Steam rotary engine, reg. patent.The finestscientific working steam engine 11611111111.5110111111111 1111111111.111111.11.111 ever invented.ts. each, 3 for 25. 6d.-Alan Hitchen, lUniversal Electric Supply 14 FILAMENT POTENTIO- Patentee and Manufacturer, Dept. 17, Burnley.[30 r 4 BROWN STREET RESISTANCES METER WirelessDealersthroughout GreatBritainare stronglyadvisedtostockpartsformaking up 7e.,phaae: ONE DOH FROM MAR KF T ST astabirthert ohms 3409CITY 1892 - 21. Each 300 ireless sets. Buy your parts direct from the factory MANCHESTER at wholesale prices.-Newtonia Wireless Factory, 13 Panel Type 4/0 Each and is, Whitcomb Street, London, W.G.2. G.P.O. Bolt No. 519. with Knob Panel type HugePurchase of ex -Government Wireless Stock. and Pointer. on Ebonite. Write for list giving full details.iso-watt dynamos, Our Large Illustrated Catalogue gives a wide ; hedgehogcoils,3s.6d. ;loudspeakers,200 range of Radio Requisites, and complete Crystal 1.111111.1....11 1111111111.111.11.111 ohms, 75.6d.;r -in.spark coils,ros. ; spark and Valve Receiving Sets for Broadcast Reception. Ito 12 volts I to 35 amps coils, 125. 6d. ; morse tapping keys, 3s., etc. etc. etc. Post free Oa Three days' approval against cash, or please call. Write fordetailedpricelistofallgoods.-,E.J. VOLT & AMMETER Galpin, 16, Loampit Hill, Lewisham, S.E.13, London. SINGLE VALVE RECEIVING Combined Dead Beat Pocket Type.New and not 1.2 s SET. German.Splendid Instrument In Nickel -plated Telephone Receivers Rewoundup to1,000 ohms, Case. Ideal for Testing Cells & Filament Current so. each ;2,000 ohms,7s.6d. ; cash with order.-M. P.O. Licensed. Hampshire, 139, Sydenham Road, S.E.26. [4 s High'y efficient. POST 5/6LIMITED Buzzers.-Speciallyconstructedinstruments by Comprises Polished PAID NUMBER Case with Ebonite uhich crystals can be set for reception, as. 6d., post Panel flitted with free.-Frank Hooydonk, Hornsey Rise, N.19. 123 r Variometer Tuner, OTHER EXCEPTIONAL VALUES B.A. Screws, Nuts, and Washers,assorted gross. Filament Rheostat, Bright Hard Drawn, 7j22 Copper, 2s.; list, ad.-J. H. Bennett, Station Road, Willesden and all necessary Aerial Wire. Junction. [32 r Tmininals, etc. etc. 3,6 per 100 ft.; same enamelled, 51 - Aerial Insulators.2 x 21 ins.Shell type, 9d. New Low -resistance Telephone Earpiecesfor £3 106. each ;2 in. Reel Type. 2. each. alve'sets,10s.6d.pair;Os. single;12 for 54s.; quantities cheaper. Quadruplecords,ls. 6d. Broad. Telephone Transformers. (Army Type.) 9'. casting each ; L.F. Transformers, 15/- each. Second-hand chloride accumulators, 90 amp. 2 volt, Fee extra. Vernier Condenser.5 Plate for Panel mount- 10s.; carriage extra.Satisfaction or money back. - ing, 4/. each.'001, 16/-.t0o5, 121- each. 140, Grosvenor Road, E.7. [1 s With Plugs, 1:- the pair. Telephone Jack and Plug,nearly new, 3s.each., Wireless Jacks. [3 s Fully illustrated High Note Buzzer.(Army Type.)Worth post free.-.M.,51, Meath Road, Ilford. leaflet of treble, 3/- each ; Tapping Keys. 2/ each. Crystal& Single Dewar Switches.D.1'.Change over, panel EASY TERMS OR CASH type, 2/- each,Small Switch Arms, 6d, each. Two, Three and Further reduction. No extra charge for extended payments. Double Four Value Write for "Comple e Supplementary Price List of Excep- Headphones, Brown, S'erling 4.000 ohms, 52/.. Mul.a.td*s Type A, Receiolng Sets, tional Values,' sent Post Free.All goods sent Carriage 21/.1 Type B,25/.. Best French "Brunet" 4,000 ohms, 25/. & 30/, postfree on Paid, but witn orders under is. 6d. add 6d. for postage British 4,000 ohms, 20/. & 22/6.Mallard Ora Valves 15/,L.F. request. Transformers, 15/8-8,20,..3 way Coilholders, 13/6 & 178, 2vlay. J.H. TAYLOR & CO., 7/6. Honeycomb Coils at list prices, according to wavelength:Vari- ELECTRICAL AND RADIO ENGINEERS. able Condensers, complete sets cr, ports, top and bottom, .00r 81,.0005 6/6. Accumulators, 4 volt 20 amps. 17N 3o amps. 20/., So amps. Macaulay St., HUDDERSFIELD. 40/. H.T..BatterY, 30 volt 7;6, 6o volt 14/. (variable with plugs). FILAMENTRHEOSTAT. 4. RADIO " Mahogany Cabinets, Ebonite Panel, drilled, for Single Valve Set 8 by DOUBLE HEAD Telephone 341. Telegrams: "Thorough," Huddersfield. 6,10/, for two Valves, m by 8, 15/6 three Valves 14 by v., 21/- with Complete RECEIVERS. terminals.Money returned hi full if you are not completely satisfied Carriage paid on all orders over 40/.. Terms: One-third with order, far Panel balance in six fortnightly payments. M0 0 - SCIENTIFIC APPLIANCES o tical and ALL Electrafi"I;igIna. G.BUSH, 119, Sutherland Avenue. London. log. LESS PARTS and Materials at Lowest Prices. British Call and see our immense stock or write for Information and Prices. Made. In Centre or London, Top of Kingrway. g - Complete SCIENTIFIC APPLIANCES, ACCUMULATORS with Cords 11 and 29, Sicilian Avenue, London, W.C.1. 4 volt 20 amp....141. 6 volt 20 amp....22/- 000 ohms, 28, pair 4 40 ..,19,'.

1111 4 60 6 60 3716

4 80 331- 6 80,, 52/- Special High (Carriage Paid) (Carriage Paid) Note PORTLAND'S PARTS BY POST These accumulators are brand new, guaranteed and BUZZER specially recommended.Terms Cash with Order. for Crystal AdjustmeMs. BASTONES, 228, PENTONVII LE RD KINGS CROSS. LONDON. N.1. Skeleton Type, g6. I " EBONITE " Mouatel on Base with Cover, Ls. d. WIRELESS BARGAINS. Bioadcasting Fee 6d. extra. SUPERSENSITIVEALL -BRITISH, 8 x 7 PHONES, 21/. 4,0 POST FR EE. HIGH TENSION 4x 4 1 3 ALL. WIRELESS PARTS & SETS.Trade supplied. BATTERY. 7x5 2 8 CRYSTAL DETECTORS, 2/6. 15 Volts3;8 lox 6 3 9 Illustrated Catalogue A, including list of Stations, Variab'e r 7 x 5 5 3 6d. post free. Type. 12 X so... 7 6 WIRELESS115,UPPLYS CO., Volts 8i , 9 6 EONS FleetStreet,E.C.4. 36 9/. x IS... 12 10 60 we 36 x i8...... 1 3 0 So 27/. 7 lb. ... 1 3 0 --NOTICE Tappings QUARTER, MAT. BRITISH The SIMPOLIA WIRELESS Co., taken every Postage Free-Any Sloe Cut , having re -designed their wireless sets, have a small stock of 3 volts. their older type to dispose of at less than cost price. 20 Single Valve Receiver Panels at 121 -each or £10 CRYSTAL SET AMPLIFYING the lot.12Two Valve Receiver Panels with tuners, low JAMES PORTLAND 401-each or £21 the lot. PANEL frequency, at 39,SINCLAIR ROAD, OLYMPIA, W.14Simpolia Wireless Co., 170, West Green Rd., Tottenham, N.I5 sina remarkablethestnt.tE sigtsincreasing extent. N,B.- Mr. Portland Stocks 200 Wireless Parts Can be readily attached to any good type of Crystal Set. Comprises polished hard. wood Case with SOLVES THE Ebonite Panel. Fitted with ELECTRADIX RADIOS. AERIAL PROBLEM Valve Holder, Filament Re- You can support your sistance, Low IMMEDIATE DELIVERY Frequency FROM OUR HUGE STOCKS aerialindoors one foot Transformer from wallsonthe in- and all Everything from a Recorder to necessary sulatedarmofthe Terminals, an Earth Clip. Labels and IND-AERIAL HOOK. Connections. The best equipped City depot. Price, These books can be attached (and inc uding all COME AND SEE US PRICES taken down) in a second, to the picture Broadcasting 9, COLONIAL AVENUE is rail of any Room, Hall, Lobby, Passage, Fees, 2/9 each Office, Nursery, etc.Almost any length Re a 0 firstopeningonleftinthe. Marconi- Set of four of Aerial can be arranged by hanging Osram " R " Minories, nr. Aldgate Station, 10/6 aerial round walls or across room.No type. Valve, screws or nails required. Makes any set including Metropolitan Railway. post free Broadcasting portable, astonishing results belong ob. Fees. Tel. Send P.O. tainted.TRY IT. LESLIE DIXON & CO, ,4 venue 4166. to -day and 17;8, 9, COLONIAL AVENUE, MINORIES, E.I. IND-AERIAL CO. (Dept. A), secure yours. 47.1 -VICTORIA STREET, S,W, 41111111=1111111111M DECEMBER 23. 1922 matter 691 1: Ws. The Battery with 40 years' Exi manufacturing experience BATTERIES behind it THE finest quality materials and experienced workmanship go to make this a battery to be absolutely relied upon to give the H.T. steady high voltage so necessary to ensure the best results in Wireless Reception. PYRAMID H.T. Battery

Batteries Volt . 3o Volt (with variable plug connection) 71 - for (POST ORDERS DELIVERED WITHIN 24 HOURS) We also manufacture complete Wireless Sets and all component parts, of which the following is a much abbreviated list. Valve Sets Broadcast Receiving Set Price complete with Britishmade headphones, 24v. 28v. 32v. aerial and everything ready for fixing-£5 0 0 Filament Resistances .3,9 plus 7/6 Broadcasting Fee. Low Frequency Amplifiers for use in conjunction Type B.K. " Ideal "Valve Accu with this set basing special transformers-Price mulator in case 4 -Volt 5o amp.. 25/. £5 0 0, Owing to the demand for these batteries, (Carriage 20 Twoof these amplifiers are capableof working a loud speaker with excellent results withina all orders will be dealt with in strict rotation. 6 5o amp. . 351 - distance of zo miles from London. Prices approximately oneshilling a volt. (Carriage 31-) Variable Condensers (of :: Ask for Leaflet 4030 various capacities) From 61 - Fixed Condensers . 216 3 -Coil Holder, complete ELECTRICAL STORAGE Unitfor usewith Standard Coils. . . 201 - COMPANY LIMITED. IllustratedListsfreeonRequest,orVisitour Showrooms

CLIFTON JUNCTION, I 219/229, SHAFTESBURY Nr MANCHESTER. AVENUE, W.C.Z. 13/N1tsGreat Queen Street, PRICES AND PARTICULARS ON APPLICATION. Wates Bros. I WAY, LONDON, W.C.2.

FOR TORRE BE EXGPI ENRNI EMRE. NT E R ALLREQUIREMENTS AT MOST REASONABLE PRICES. COMPLETE SETS OF PARTS SUPPLIED, FROM CONDENSERS TO SUPER -REGENERATIVE SETS(IN STOCK). BROADCASTING ENGINEER IN ATTENDANCE, INSTRUMENTS REPAIRED,ETC. EXPERIENCEDJOHNRADIO BANKS & SONS, HAS NOW BEGUN! 14-18 Duke Street, t5 minutes from CENTRAL STN.)LivERp001 Have you obtained your Set yet ? 'Phone 4424 Royal. (See Windows.)Catalogue Post Free. Our No. 1 CRYSTAL RECEIVING SET is BEGINNER'S GUIDE TO WIRELESS suitableforreception of all broadcast matter for a Explains in plain, everyday language, everything range of 20-30 miles. beginners wish to know about Wireless Telegraphy. HOW TO ERECT, CONNECT, AND MAKE TYPE APPROVED BY P.M.G.Reg. No. 126. an: the apparatus required for reception of telephony or morse, Price 35s. and full instructions and diagrams for making coils, tuners, and Plus 7s. 6d. broadcasting commission. complete valve and crystal sets.112 pages, price 1/- post free. SAXON RADIO CO. (Dg.), South Shore, BLACKPOOL 'PHONES.British made, wound to 4,000 ohms. 32 page Catalogue of Wireless Apparatus, 3d. post free.' Price 25S. AERIAL EQUIPMENT, comprising 100 ft. 7/22 .90 lk 'NAM Rat 'Satl i1 lay S.W.G. Stranded Aerial Wire and Insulators, 4/- extra. COMPLETE EQUIPMENT, ready to " Listen - aI,mas(lift IJ in." Price £3 3 0 JUST OUT Plus 7/6 broadcasting commission. "Excellent R e sults." "Costs Nothing." WIRELESS HANDBOOK 8 DIARY West Kensington, r8th Nov., 1922. " You might like to know that in spite of the fact that I have a 3-valve. 1923 Set, I prefer listening -in on the Broadcasting Co.'s Transmission of your No. i Crystal receiver, which givesexcellent results,and unlike Valves Price 2/6 net costs nothing to run." Ve Acomplete Letts' Diary with go pages of valuable wirelqs information and the usual pages of useful general information. Beautifully bound in L ii leather, it will form an ideak Xmas gift.Get someone to buy you one. Write for Illustrated Catalogue of all Radio Accessories ObtainablethroughallBooksellersordirectpostfree 2/8k from

941 BOWER ELECTRICLTD., Rabb' Pm 3ttb., 11111111111111114 : 15, GRAPE STREET; : DEVEREUX BUILDINGS, STRAND, LONDON, W.C.2 SHAFTESBURY AVENUE, London,W.C.2 111111110/41 1st 111 Ma V#7 LP .1 LIIJ=U.' Our Wes 692 DECEMBER 23, 1922 RADIO CHRISTMAS GIFTS Sterling No, 1 Crystal Radio Head Receiving Phones Set (Manufactured under Brown's Patent No. 131353/18 by Sole Lice'nce)

Of the highest efficiency. Constructed on the mostscientificprinciplesand togive Specially designed for Broadcast reception, very selective and simple to a comfortable fitto the ear cf the user. op rate.Complete with one pairof Double Head Telephones and with special coil for Paris Time Signals.Range about 25 miles. Write for Leaflets Nos. 321 and 325. Write for Leaflet No. 324. 'o he obtained from all Dealers or direct from WE GUARANTEE STERLING TELEPHONE & ELECTRIC CO., LTD., thatall Broadcast Radio Telephone House, 2101212, TOTTENHAM COURT ROAD, LONDON, W.1. Apparatus sold by us conforms Telephone: Museum 4144 (7 lines.) Telegrams :" Cucumis, Wesdo, London." with the con dition s of the NEWCASTLE -ON -TYNE : WORKS : CARDIFF Broadcasters' Licence issued by 9, Clavering Place. Dagenham, Essex. 8, Park Place. the Postmaster -General.

Your electriclight catches the wireless exactly as an aerial does. Plug a "Ducon" into any lamp holder or wall socket, connect it to, your wireless receiver and you will receive the broadcasting perfectly. USE A "DIXON" and you don't need an aerial.

"Ducons" areperfectly safe-each oneistestedto 1,coo volts, they'consume no current and do not affect the electric light in any way. The Ug a0 isobtainable from leading wireless dealers,electrical contractors and stores, or direct from the makers. Dealers not yet stocking are invited to write for Trade To Ins, Over 50,000 in use. The Dubilier Condenser Co. (1921) Ltd. Duce nWorks, Goldhawk Road, Shepherd's Bush, London. TeWhon,7-Hannnersmith toSj. n!eyrams-llivolIcon, Phone, London.

ranted and Published in England by CASSELL & COMPANY. Lulu -rap, Ludgate Dill, London, E.C.4.Sole Agents for South Africa, CENTRAL Naws AGENCY, LIMITED. Saturday, December 21 292:, (x,9'3 A COMPLETE VALVE SET FOR £4

Put Your t;flieulties to Zly

No. 30 SATURDAY, DECEMBER 30, 1922 Price 3d.

Manchester Broadcasting -station Studio(See page 707)

SINGLE -VALVE REGENERATIVE CIRCUIT :: WIRELESS FROM CLOUDLAND

MORSE MADE EASY :: CRYSTAL MOUNTING THE DYNATRON MANCHESTER BROADCASTING STATION IMPROVING A UNIT SET ematzur Wireiess 694 DECEMBER 30, 1922

ECONOMIC LE CTR I LTD. ten4ITCHELFONES Are not a spasmodic production to meet a sudden demand, but have been on the market for over three months, and during this period 27,000 have been distributed to thetrade, and consequently we have not been able to offer them direct to the

retail buyer. 1,000 per week are now available, and we announce CRYSTAL DETECTORS, 5/6 a

Write DELIVERY FROM STOCK

To -day for 40 - HEAD RECEIVERS Youpostyourorder,orcallatour Page WIRELESS From 12/6 List Post Free premises and get them at once.Think

4d. what this means to you-you, perhaps, who 250 Illus- IQ ENCLOSED have been waiting and arestillwaiting. trations. CRYSTAL DETECTOR, 12/6 Standard resistance 4,000 ohms, double headgear with double headstraps,comfortable,highlyefficient, and foolproof 25/- per pair.

Special Terms to Traders and deliveries

that will surprise you.

VALVE HOLDERS, 119 MITCHELLS Electrical & Wireless Ltd., PostalAddress:McDermottRoad,Peckham, S.E.15. Plead Office 10, FITZROY Retail Address: 188,Rye Lane, Peckham, S.E.15. SQUARE, LONDON, W.T. 'Phones: New Cross 1540/1541. Showrooms: Telefihone BlanchShowrooms 6r.Works: 303, EUSTON ROAD N.W.I. MUSEUM 0355 TWICKENHAM 11/4)0-GREAT BRITAIN'S GREATEST WIRELESS STORE-4)

LIi 'A011 14,1,1:h'el.1111J'A1.1 :A. J'01 tk1111.1 Jti [DELKiri*E1***D:m(f=10*[]**,***DEI:Lic.Diunim h.J riu Altar's Gift I=1 JUST OUT j Ll AT LAST ! !! O WIRELESS HANDBOOK t?DIARY El 1923 ElReallyEfficient B. B. C.Setsat Price 216 net LOW PRICES A complete Letts' Diary with go pages of valuable wireless information El and the usual pages of useful general information. Beautifully bound in 1111 leather, it will form an ideal New Year's gift. Get someone to buy you one. ElCOMPLETE OUTFITS Ready to Obtainablethroughall Booksellers ordirectpostfree2/81 from tig One Valve£9901 tk Complete IncludingO abin Vass 30, Two "ii I=1 13176 I DEVEREUX BUILDINGS, STRAND, LONDON, W.C.2 El with all Tuner,etc.i Three 16160 1 Royalties 111401 LIi'Mt 11101 \or Four 19190 Packing and Carriage free in Great Brlain. El STARTLING REDUCTIONS EJ Accessories are : 1 um imiiY m0 Ebonite Condenser Dials, Engraved 0-180° and pair 4,000 ohms Double Head - filled white with Knob, Brass Bush and Set Screw2'6 Elphones ; 1 Accumulator ;2 H.T. Batteries ;Aerial Dial only ...... 1/6 , ttit Aluminium Condenser Vanes per doz. ... 6d. Ei Wire ;Insulators ;Lead-in Rod and necessary Earth Spacer Washer, small 3d. doz.; large 4d. doz. D and Connecting Wire ;and Valves. Knobs, with 2 BA Brass Inset ... 3d. A.E.G. and Halske Valves for recti. 11 Grid Leaks (enclosed), 2 meg. ...1/- lying and amplifying (tested) ... 7/6 El Grid Condensers ...... is Crystals (special selected), Bornite, NOTE I!Weare45 miles from Writtle, 70 from Marconi House, Filament Resistances ...... 316 Zincite, Galena, Silicon, Carbon. ... 130 from Birmingham, and 170 from Manchester, and 41 - Crystal Cups with Screw ... 3d. undum, Copper Pyrite, Graphite, ... El get all these stations on Fusible. Alloy, per stick ...... 4d. Tellurium, etc...... 6d. anyof these sets, Verb. sap. El Inductance Tubes, 12' X 3 ... Egg Insulators, Green ...... 4d. Reel best quality...... 3d. El WRITE : [A 11 It IV X 4 ...... 8d. ,, ,9 , to x 3' ... Hellesen 36 v. Batteries with Tap- ... ,, re x 6' ...... 1 3 pings and Wander Plug ... 8 6 * Sliders and Plungers ...... 8d. Essex 15 v. H.T. Batteries...... 3/- Lc Sq. Brass Rod, re x r x l'... Ebonite Leading In Insulators ...1/8 :Cook's Wireless Depot Enamelled Wire, 23 gauge, lb. Perikon Detectors on Ebonite Com- El El Aerial Wire, 7125, Stranded, too plete with Crystals ...... 4/ - lil EC Valve Holders, Screwed Legs " Ubique " Crystal Set Complete... 15/ - 61 and 63, St. Matthew's Street, LC DELIVERY BY RETURN GUARANTEED Postage extra. El IPSWICH SUFFOLK. Office 5 Showrooms CI 499, GROVE GREENRD., :: Wholesale only :-9, Bedford St. :: El THE ESSEX WIRELESS CO LETTONSTONE, E.11. Telephone-WANSTEAD 749. (1 mtn. from Station,G.E.R.) El El OMMMEDMEll2MME11DMMOOMMIKIIMMMMDE3*MrliElOMEI* C1314 Etectrics No. 30 December 30, 1922 Wireless from Cloudland

T is truly a wonderful -:'"''',,11-111,117[!!!111711:`1 ;13711117111111,,,,,,, ',1'!!!,!:1!1,1:!,!3:111:111:1,1.1,1!,,,,!1:111111r:1111111[0i111:!:1:!:::111:1!,:11111:,:,'Ilil15 way"itis vibrating Iexperiencetotravel throughoutits w h o l e above the clouds, out of AIRCRAFT WIRELESS :: WEIGHT AND EFFICIENCY structure. N o t h i n g sight of the earth, at a POWER :: EARTH :: ENGINE NOISES VIBRATION could be more injurious, speed of So or i)o miles THE " HEAVISIDE "LAYER of course, to crystal re-

.an hour, and carry on a El; ception. Inorderto II "'' I' ".,'.' I, II '111 f..:11111111111111111111AIIIIIIIIIIIIIIIIIIiIIIII!III: communication with an V111:111'.11011Will!:11111111,11!!!;11'.;::1:,.!,:' .' I' tll; 11111"I .:;1:111 JI ":11::1:1111'1 Illilallllll \I .1Llp keep the contact point invisiblewirelessstation some hundredsthat was incurred by the presence .ofasteady it was often necessary to screw it of miles away.Flying is in itself a most" spark" in any kind of aircraft.Need- hard down upon the crystal itself, thus re- exhilarating mode of travelling, and when lesstosay,this danger was frequentlyducing the sensitivity of the latter.Mag- to this is added the excitement of tryingexaggerated to a ridiculous degree at first,netic relays were extensively used in those to keep in touch with Mother Earth byuntil it became demonstrated in the coursedays to procure signal amplificationin wireless there is no more interesting andof time that, with proper precaution,it aircraft.The adjustment of these, how- fascinating experience to be found. constituted as unlikely a source of dangerever, was even More sensitivethanof Needless to say, aircraft wireless formsas any other part of the machine's equip-crystals,- and they were usually carried in aspecialised branchofscienceto -day, ment-which, of course, was, not saying athe "tail" of the machine Where the least althougheightyearsagopracticallygreat deal in those clays ! amount of vibration was experienced. nothing.. had been clone towards the de- velopment ofthis method of signallingEarths Biimping from cloudland.The late war gave the A pointwhichseems ofparticular The tuner, --ofcourse,couldnotbe first impetus in this direction, when someinterest to many amateurs in reference tocarried in. this positiOn because of the need of the greatest scientific minds of the dayaircraft wireless is that of making a con- forperiodical readjustment ofthe con- set themselves to conquer the many diffi-nection to earth.How isitpossible todenser, etc. When the- relays "conked,"- it cult problems which impeded the applica-connect an aeroplane instrument to earth ? was impossible to get them going again tion of wireless principle's to aircraft. Well, the answer is that the function ofduring flight because of theirinaccessi- an ".earth " with any " open " aerial isbility in thetailofthe- machine.This Weight and Efficiency to serve as a capaCity, to balance that ofwas oftenresponsiblefora number of The greatest of these problems-and it isthe aerial itself.The aerial -earth system falsestartsatthe commencement ofa one which continues to exist to -day in nothus acts as a condenser, between the two flight.If the aerodrome happened to be small measure-had reference to the needsides of which the received or transmitteda bit "bumpy "atall,itwas an even for reducing the weight and size of aerial impulses oscillate.The first attempts to.chance as to Whether the relays would or wireless instruments toa minimum:Itprovide a suitable earth on an aeroplanewould not be thrown out of action in the must be remembered that when aircrafttook the form oflong condenser tubescourse of "taking off." wireless began to develop, aeroplanes andwhich were carried in a separate part of airships were themselves in no very ad-the machine.It was found later that the Valve Troubles vanced stateof development.This,of metal bed of the aircraft- engine afforded a With the advent of the transmitting and course, led to a conflict of interests be-still more satisfactory earth.A numberreceivingvalve,ofcourse,theaerial tween those who were responsible for theof leads are usually taken tothis fromwireless operator began to look forward to efficiency of the aircraft itself and thosetheearthconnectiononthewirelessa life of luxury and ease.But if valves whose task it was to make the wirelessinstrument. broughtadvantagestheyalsobrought gear as efficient as possible.On the one troubles. Fromthefirsttheynever handtheefficiency of theaircraftde- Engine Noise seemed to take kindly, to the air.Valves pended largely upon its lightness and its Another important problem in receivingwhich werequite well-behaved on- the amount of available space for Passengerson board all types of aircraftis that ofground always "howled" on being put and cargo.The, efficiency of the wirelessengine noise.The roar of an aero-engine intoanaeroplane. Moreover,high- gear, on the other hand, depended to an atclosequartersisterrific,though, tension leads were tricky things to "mess almost equal degree upon itsheavinessstrangely enough,onecanbecomeso about with " in the limited space at one's and the amount of space it occupied. accustomed toitduring flight asto bedisposalinthe cock -pitof a machine. almostunconsciousofit. To -day,of And if valves amplified signals, they also Power course, with valve amplification, -its effect amplifiedotherthings,such as the In those days the power for the trans- ispracticallynegligible.At thattime "ripple" produced in the phones by in- mitter was always taken from accumula-the only thing to be done was to lock itduction from the magneto of the engine. tors. This meant that thegreater theout by shutting your head up in the best But fresh troubles are, alas!rising up power used the greater the total weightfittingflying helmet that could be pro-to meet the new generation of aircraft and the space occupied by the wireless in-cured.How one's ears used to ache after observers. There is,forinstance,that stallation. Anotherdi advantagefroma long flight under such conditions ! importantproblem ofthe"Heaviside which the pioneers of aircraft wireless suf- Then there was the difficult problem oflayer."Now, if that could only be lifted fered emanated from theslightdangervibration.When an aeroplane is " undera little.... AIRCRAFT OBSERVER. ° entateurWireless 696 DECEMBER 30 1922

ED ...... 4111.411. 0......

A Dutch Amateur Wireless StationI DO0.0-00.0.0.000...... II) AMATEUR interest in wireless is now W. Tappenbeck, and shown in the accom-range of zoo miles and apparatus for ex. I-1 universal, and we are constantly re-panying photographs, is of special interestperiments with very short wave -lengths. ceiving particulars of installations from allowing to the wide varietyof apparatusThe second photograph shows the receiver,

Transmitting Apparatus. Receiving Apparatus. parts of the globe.The Dutch amateurdisplayed, much of which is of an experi-whichhashoneycombcoils,amplifiers station(Noordwyk Aan Zee,Holland),mental nature.The photograph on theand four -electrode valves, together with a owned by an enthusiastic amateur, Mr. leftshows asparktransmitterwitha quantity of accessory apparatus...... 411.41...... 0 ...... arranged as detector and amplifier in the Single-valve Re- usual way.The function of the vario- Morse Made Easy meterintheplate circuit(plate vario- generative Circuit meter) is to tune in and feed back into the The Group Method grid the added voltage of the plate circuit. o 411.411) ..... 41)110. 111) For simplicity and ease in operation this ..... 411411...... THE query" How canIget morecircuit has a distinct advantage over any MANY amateurs seem to think that the volume from my singlevalve ? "isother type 'of regenerator, and the expert- Morse code is very difficult to learn, causing much racking but anyone following theadvice given of brains amongst ex- below will find it quite easy. perimente rs. How The code shouldbelearnedinfour many have thought of different groups, the easiest signs being in employing variometers ? ) the first group, which should be learned These wonderfullittle thoroughly. components are perhaps L.T FIRST GROUP. not too widely known E-"'is opposite T in this country, but in I .. HT America, the Land of S 0-_- Hook-ups, they are ex- FILAMENT RHEOSTAT H tensively used. SECOND GROUP. PHONES VARIO-COUPLER The variometer, what A is opposite N it is and what it is not, was fully described in U - >I D - V - t, B a recent issue of 'G AMATEUR WIRELESS, CI ID THIRD GROUP. W is opposite and the purpose of this P VALVE too 1111491 - G - K short article is to give R - 71 )) PLATE VARIOMETERVARIOMETER GRID VARIOMETER an example of one of P ...- f, ,, X=a :mem its many useful adop- L. GRID LEAS & CONDENSER - - tions. Inthevery Single -valve Detecting and Amplifying Vatiometer Circuit. F - 51 Q - simple circuit shown in FOURTH GROUP.

the accompanying illustration,itispos-mcnter will find it well worth trying out. sible to obtain both detecting and ampli- " OH-JAY-AII." -- No opposites fyingfromonesinglevalvealmost Please mention "Amateur Wireless" in . I equal to results obtained from two valvesreplying to advertisements. C. F. DECEMBER 30, 1922 697 (Iiiiateur Wireless

41, 4i. .K>C<><><><><>040-<><)<><>0(> 4011.411.110.4111.4, 40411041r010.4041.4.110.411. "A W," Ideal Unit Receiving Set.-V SOME ADDITIONS AND IMPROVEMENTS

0<><><>11110.4.4* 410, .411.<><>C0C...11%, <><>.C.-0C.GX><><>411.411.40,11, 41.41oocococ0 WITH even a single stage of high- taken in fitting up a means of controllingof potentiometer can be bought cheaply frequency amplification the set maythe grid potentials, for nothing is morefrom those firms which deal in Armysur- be found liable to oscillate when it is leastannoying than to find that big variationsplus stores. wanted to do so. We must therefore checkin the tuning occur whenever the hands With high -frequency valves the tendency this tendency by devising some means of controlling the potentials supplied to the TERMINAL grids of the valves which are amplifying PANEL at radio -frequency, otherwise the set may be very difficult to handle satisfactorily.

Self -oscillation Though slight self -oscillation is unlikely to cause re -radiation or interfere with other people,so long asthe reaction coilis loosely coupled to the secondary itwill make the reception of telephony very in- distinct.On music its effects are appal- ling; singers seem to be hoarse and not quite true to pitch, whilst instruments may produce discordant sounds.The most dis- tinctof speakers appears to be having Fig. 1. --Wiring Diagram of Three -valve Unit Set with Terminals, H.F. Rectifying, trouble with a half -swallowed potato.The L.F. and End Panel. presenceofself -oscillation makesitselfapproach or leave condenser knobs and tooscillateisatitsstrongest when the felt even when spark signals are cominginductance handles. grids are supplied with a negative poten- in, depriving them of their sharpness and Many owners ofreceivingsetssuffertial.As this potential is reduced towards causing a mixture of rushing, rustling andfrom self -oscillation troubles withoutzero the oscillation noises die down, ceas- hissing noises When the coupling betweenrecognising them or knowing that they caning altogether when the potential becomes the primary and the secondary coilsis becured*Comparatively- few"ready-slightly positive.The simplest and most tightened. made" sets have any form of grid control,obvious solution ofthedifficulty would If thesetis properly controlled therebut itis luckily not a difficult matter tobe to alter the wiring of the panels so that should be none of the squeaks and squealsadd it to most types of apparatus. the secondaries of the tuning inductance and the high -frequency transformers are . . connectedtothe plusleg,ofthefila- ment instead of to the minus.This, how- Fig. 2.-Grid-control Cir- ever, has serious drawbacks, since a posi-

cuits of Three High -fre- HT+ ',NJ N.;-11 tive potential has a damping effect, and quency Valves. HT- we must, if we are compelled to use it at LT- all, make it as small as possible. LT - The way in which the problem is solved will be seen from a study of Fig. i,which shows the wiring diagram of a small com- plete unit set consisting of 'three valves, To DPCO a radio -frequency amplifier, a rectifier and Swacr, anote -magnifier. Thefifthterminal, which hitherto we have left neglected, is LOUD SPEA now brought into play, and an end -panel, whose details will be described later, has been fitted. Grid -voltage Control If you trace out the course of the grid To Fixto potential of the H.F. valve, you will see To SLIDER TERMINALS that before reaching its destination it must pass through a variable amount of the resistance windings of the potentiometer, whence it travels by way of the fifth ter- Fig. 4.-Wiring of End Panel with Four Fig. 3.-Upper Side of End minalsandtheirconnectionstothe Pairs of Phones in Series. Panel. secondary coil of the tuning inductance. After passing round this coil it arrives on that commonly occur when searching for The apparatus required issimple andthegridofthehigh -frequencyvalve. telephony transmissions. Further, capacityinexpensive, consisting of a condenser ofThus the potentiometer controls the grid effects will be reduced to a minimum evenabout .005 mfd. capacity and a potentio-voltage, but does not interfere with the if they are not altogether absent.This inmeter with a maximum resistance value ofpassage of high -frequency oscillations in itself is an ample repayment for the troublefrom 30o to 45o ohms.Quite a good typethe circuit, a by-pass for them being pro- it-Acta- Wyss 698 DECEMBER 30. 1922 videdinthe.005bridgingcondenser,formerisconnected to the leads- shoWnfitted it has no connection., merely serving which, by the way, should have mica, notrunning from the double -pole change -overas a cut-out for the leak.This stud will paper, as its dielectric. switch to the loud speaker. not be needed if the grid -leak is of the Let us suppose that when full negative The terminals on the right of the panelcartridgepattern,inwhichcaseone potential is being supplied the Set showsare for the telephones.When more thanthrows the leak out of action simply by signs of unwanted oscillation.The sliderone pair is in use receivers should alwaysremoving it altogether. ofthepotentiometerismoved towardsbe connected in series, not in parallel as the middle, increasing the resistance andis often done.The swinging hooks enableOther Modifications reducing the negative value.Oscillationany number of head -sets up tofourto Other modifications and improvements may cease before the mid -point is reached,be used with a minimum of trouble.Most willnodoubtsuggestthemselvesto but ifit does not we continue the move -people prefer to turn on the loud speaker when friends come to listen -in, but there isno doubt thatthesounds produced by telephones are clearer and freer from 0 distortion;hence many amateurs never employ a loud speaker.Though there are many excellent types on the market none of them probablyisperfect initsper- formances ;theloud speaker has, how- ever, onedistinct advantage ifyou are using the set for long periods :it relieves you of the pressure caused by the heall- bands which, to me at any rate, becomes intolerable in time even with the lightest makes of receivers.With this panel the telephones can be used normally for deli- cate work, the loud speaker being switched on at intervals to give the head a rest. Fig. 5 -Upper Side of Improved Detector Panel Fig 6.-Wiring Liagram of Under Side of Improvements Improved Detector Pant!. ment of the slider, thus giving the poten- Let us now see how the existing set can tial a slight positive value.Experimenthe improved.The high-tension batteryreaders who make such a unit set as that will show the adjustment that gives theshould be bridged by a by-pass condenserwhich has been described in these articles. most satisfactory results. as shown in Fig.r. Besides providing aThe keen amateur is never quite satisfied Do not forget, by the way, that so longfree path for oscillating currents this con-with hisset asitstands, but is 'always as the low-tension battery is connected a thinking out some way in which it may is flowingdenser serves to eliminate battery noises current of 3o milliamps or so by keeping the H.T. current cornstant.Itbe made to give better perfor=mances.In throughthepotentiometer. Thisisa should beoflargecapacity-a r mfd.this lies perhaps one of the chief delights small amount, but if the battery is not dis- of wireless, for there is no thrill to equal connected when the setis out of use itsMansbridge condenser will do admirably. Convenient placesfor mountingitare that which one experiences when- a change charge will gradually leak away. either below the top of the table or onof wiring or the addition of some care- Whentwoor morehigh -frequencythe outside of the terminal panel. fullythought-out "gadget"isfound tc valvesareinusethewiringoftheir give an increase in efficiency. In this way Figs. 5 and 6 show how the valve -recti- panels is as shown in Fig. 2. fying panel may be improved by the addi- If the set is carefully made up it will the grids of all of them are controlled by be found to give first-rateresults.The is not as a ruletion of a three' -way switch, which can be the potentiometer, and it made up on a small ebonite base, by usingworking isquiet,and signals come in difficultto eliminate self -oscillation alto- with good quality and strength. With gether with a minimum loss of amplifica-three of the studs made for the selector switchesoftappedinductancesanda only three valves arranged, as shown in tion. laminated arm. Fig.r,broadcastingstationswithina End Panel Valves of different types vary consider-reasonable radius come in with sufficient Details of the end panel are given inably in their working.Some do best withpower to enable a loud speaker to make Figs. 3 and 4, which show respectively itsthegrid -leakinparallelwith the gridspeech and music pleasantly' audibleto upper and under sides.Made in this way,condenser, others with it placed betweeneveryone in a good-sized room.With two it becomes a neat and handy addition tothe grid and the minus leg of the filament,or threestagesof high -frequency,tele- the set, which well repays by its useful-others again with it connected to the posi-phony should be heard not only from any ness and the time that it saves the troubletivelow-tensionlead. Experiment willof our broadcasting stations, brit also from taken in puttingittogether.The loudshow which isthe best position for anymost, if not all, of the European centres. speaker is fastened down near the top ofvalve, and this switch provides a handyThe receptionofvery long-rangetele- the panel ;ifits base is too large tofit wayofmakingthenecessarywiringphony depends, however, largely on the comfortably,a small pedestal should bechanges without any trouble.Very softquality used, to say nothing of the skill made forit.Immediately below itis avalves do not require a grid -leak; theseof the individual operator, which counts double -pole change -over switch, by meansmay be catered for by providing a fourthfor a great deal.Practice makes perfect; of which either loud speaker or head tele-neutral studforthe switch -arm. you will be surprised to find how greatly phones can be put in and out of operation In making up this arrangement grid -yourreceptionsimproveasyougain in a moment. leak and condenserareseparated,the familiarity with the set and its working. Belowthisagainisthegrid -controlformer being mounted on its own ebonite The lastarticleofthe present series potentiometer.If it is desired to use low -block.The condenser is wired as beforewill deal with the operation of a multi - resistance phones and loud speaker, thebetween the grid and the input terminal.valve set. R. W. HALLOWS. telephone transformer should be mountedA second lead is taken from the grid. to on this panel.It is possible without anythe leak, and thence to the -switch arm. Erratum.-A misprint occurred in difficulty to make use of such mixed gearThe studs arc wired respectively totheArticle IV. in the first line of paragraph 4 as high -resistance phones and low -resist-input terminal, low-tension negative andon page 64;.Low -frequency condensers

ance loud speaker.In this case the trans -low-tension positive.If a fourth studis should read low -frequency transformers. - DECEMBER 30, 1922 699 ettiateur Witties3 lyegotMullard Accessories

1 hewireles3 components withaworld-wide reputation of many years standing. They will ensure your getting a set which looks well, works well and speaks well. For receivingvocal and instrumental items you must have MULLARD "ORA" VALVES to get the best results. OscillatesRectifiesAmplifies. Specially recommended where good amplification is required. The "Ora " Valve requires about 3.8 volts on the filament and 30 volts or over between the anode and filament for efficient results. Standard Price 1 5/- each IMPORTANT NOTICE Thegre AtdemandforMullard" 0 RA " Valves and other accessories has compelled us to open much larger works.A greatly in- creased output is now available.

The Mullard "R" Valve \.. is now reduced in price from 22/6 to 1716. te," GoyOc o o4) QC'

ct ,X C? Co.Lfd. -4" o Milliard Rad ioVal.ve c'

CP Nightingale Lane, Balham, 45, 1S5 b\ts0 4'.. co° - . y 1, , ebbZ> . CP k!!,, 4..\''' ....4, ..$ .2,, ,tit cl, , y0.,sac.4,tv ,.. ,.4 * y,.0 ot 44Ktb e,cg 0o Cont rac for s to H.MAdmireilty, Atl ;''''t.'C'S'cP oc' 4/ N\ e os. ao,, V/arOfficeRcyalAirforce &PostOffice, 04Czy.,J"' ze ..-1''o'' .t:is. ,P c, c' 0., 0,0 Q. tiQy Telephone: Codes: Telegrams: <39.- Nt,'". tAtterseaABC (5 Ed) Radiovalve,Wandscom, e oc, . 0 ae 1068 Bentley's London. ,Vb \O 49 CY 000' 4,'Ne7e O 0 s7nerlw s 4e' glialaWila RADIO nu)VALVE nit ':cs'4%' t.t's .44b. Cv. mateur Wireks3 7C0 DECEMBER 30, 1922

THE IDEAL ACCUMULATOR FOR WIRELESS FULLER "BLOCK" Type ACCUMULATOR The only Accumulator which will boll its charge from 12 to 18 months when not in use

Fool -proofNon -Sulphating::Unaffected by Short Circuits A Summary of the Principal Advantages of Block Accumulators. Instead of using thin plates, with their liability to buckle, the Cells are constructed with electrodes in which segmental blocks of active material are carried on small grids and wrapped in porous material. The result is that the electrodes are free from the possibility of injury either by vibration, short circuiting, or sulphating.They also have the special that they will hold their charge from 9 to 18 months without the E.M.N. falling belowfeature2volts. The Cell is constructed of two or more segments.The grid being buried in time Block is tahe,ted upon by the electrolyte, and consequently there is no fear of trouble from "growth." Some of the advantages of the Block accumulators are:- (1) They are " fool -proof." (2) There are no plates to buckle. (3) Itisimpossible for thecellsto he spoiled through accidentalshortcircuiting, and even if the terminals are joined by a metal bar, the cells will not be spoiled or seriously injured. (4) They will retain their charge for many months. (5) Sulphating cannot occur to any serious extent, as thisismostly caused through cells standing in a discharged state or being discharged through accidental short- circuits. (6) The Blocks are so constructed that they cannot swell or grow, and this prevents the

: external box or container being cracked or broken. (7) If the cells are neglected, or left in charge of inexperienced hands, no serious harm can he done, as even when discharged down to 1.5 volts, they recover their voltage and maintain their recovery, thereby preventing sulphate forming. (8) They are lighter and have a higher capacity per pound weight than ordinary plate Type 640,complete'i' Jin Teak accumulators, and ca q he re -charged an indefinite number of times. -. Intermittent TYPE. VOLTS. Capacity at Makers Price. Our Price. 20 -hours Rate.* DO NOT MISS THIS £s.d. £s.4. 440 4 40 2 150 1 126 640 6 40 42 6 289 SPECIAL OFFER 13 L 440 4 80 3 100 280 We have made a special purchase of 1,000 B L 640 0 80 55 0 3 12 0

B L 455 4 110 4 1 0 2 150 POLISHED TEAK CASES B L 655 6 110 6 1 6 426 (as illustrated) B J 4120 4 120 4 80 2 16 0 B J 6120 6 120 6 120 to take Type 640 03 volts 49 ampere hours) 440 complete with outer terminals brass hinges B L 480 4 160 4 90 3 4 0 and fastener, and solid leather strap. BL 680 0 160 6 13 6 4 160 We offer one of these cases, as long as the stock lasts, B L MO 4 220 6 1 0 400 B L 6110 0 220 8 9 0 600 ABSOLUTELY FREE of CHARGE For 12 -volt batteries, double the price of the 6 -volt. *NOTE The Ignition Capacity is double the Actual Capacity taken at the to all purchasers of this particular battery 20 -hour rate. Price for Teak Carrying Crates or Cases on application. at £2 8s. 9dThe value of the case alone is The name " FULLER " is behind every one of these batteries, a certain 15s. Please add 3s. 6d. to cover cost of guaranteeof quality, for nothing but the best and purest materials are carriage by passenger train. used inthe manufacture of their products. Li fil The City Accumulator Co.

I 79, MARK LANE, LONDON, E.C.3 Wtolesale and Retail Distributors for Messrs. BURNDEPT, Ltd.Same Trade Discount Allowed as by Manufacturers. AGENTS Phones: London: U. V. ALBROW, 56, George Street, Baker 8.Wales: SOUTH WALES WIRELESS INSTALLATION Telegrams : AVENUE Street, W.1. CO., LTD., 18, West Bade Street, Cardiff. Glos.: BRISTOL WIRELESS CO.,52, Cotham EEL -TYCHE 1116, 91,92- 93 FEN, and 9916, Bristol. N. Wales, Lanes., Ches. & I.O.M.: THE " ALL- Leicester WALTER Rows,LTD.,96, Granby Street, BRMSEI " WIRELESS MANUFACTURESco.,LTD , LONDON." Leicester. 18, Vauxhall Road, Liverpool. Codes: A.B.C. (5th Edition) and LIEBER'S DECEMBER 30, 1022 701 emateurVreless

Receiving Problems in America PROBABLE"wouldmakemostinterestingreading. phonic,producing Wireless

none but, thoseThe directionoftheaerials. concerned a slightly metallic- Blind Spots The whoseaerialsare should.be mentioned,as wellasanytonein the re- Oscillators Low -temperature high andsituated screening of them that may exist. ceivers, but thisis inopenpositions notbad enough Valves have much chance * * * * 'tobeunpleasant. Micro of hearingama- Have youeverwrestledwithaset There is no doubt teur or broadcast-thatrefusedtoworkuntilyour beadthat when they can ing transmissions from the United States.buzzed, your brain reeled and your heartbe manufactured and sold at a reasonable Itisnot,however,atalldifficultto was sick within you?Have you everprice they will displace all other kinds for pick'upsome -ofthebigAmericantraced out the wiring and founditall receiving purposes. stations provided that you have a set ofcorrect; thought of every possible fault, inductancessufficiently. largeto _reachlookedforitand founditnot?Have * thegreat wave -lengthsthattheyuse.you ever in blank despair resolved to give Interference from sets,whose owners Tuned by a .00r mfd. condenser in paral-up wireless and taketo knitting? Of will allow them to oscillate inspite of lel, a honeycomb coil of 1,25o turns willcourse you have, orif you haven't youprayers and threats,is becoming beyond be able to deal with most of them, and onwill some day.'Tis a thing that happensa joke.There are times when re -radiation these long waves a fair amount of capacityto every amateur wireless man sooner oris so bad that one switches off in disgust. in the primary circuit does not greatlylater.My time of trial came a day or twoAnyone who has a valve set containing matter. Ifyouhave a coil -winding ago.Signals,if they were there at all,only primary and reactioncoilsshould machine you can make these big fellowsWeresofaintthattheywerebarelyrealise that he is about as popular with for the cost of the wire, which is not a bigaudible. Nothing appeared to' be wrongwireless users as a mad dog is amongst item; or you can purchase the inexpensiveanywhere in the inner parts of the set, still ordinary men.There are, three 'people but not very efficient slabs.These last aresomethingwasveryobviouslyamiss. near me who deserve to be hanged from not too easy to use owing to their largeTake three guesses.Give it up?Well,their own aerials. Ido not know their self -capacity. Annapolis (N S S)worksthe grid condenser of the rectifying valvenames, butI can always recognise them on 17,000 metres, sending at1.3o a.m.,had broken down in some mysterious way, bytheirpeculiarmethodsoftuning. 1.30 p.m., 4.55 p.m. and so p.m. G.M.T.and that was that.You'll agree thatit Ham -headed Henry moves his condenser Marion (W S 0)is engaged almost con-was about the last thing that one wouldknobs with greatmajestic sweeps- tinuously on Transatlantic traffic, workinglook for. SQUEeeeeEEEAL.Timid Thomas, on the on 11,5oo metres, and Tuckerton (W =G G), Itis curious to observe how often theother hand, prefers the method of rapid whose .wave -lengthis16,too metres;is obvious will escape one's notice when onejerks from sidetoside-squeak-squawk, seldom silent for long. is looking for faults.A friend not longsqueak -squawk, squeak -squawk.But the ago spent the bestpartof the day inworst of all is Oscillating Oswald, who is * * *- taking hissettopieces and puttingitnever quite satisfied with his tuning; he I. A. has sent a. most interesting lettertogether again in the hope of finding out -is always giving things a touch here and with reference to the paragraph on blind what was wrong with And all the timea poke there.Could I but find a good, spots -which appeased in "On Your Wave-the filamentofone, valve was restingsound, .old-fashioned witch I would have length " a week or two ago.It was men-gently uponthegrid.Another friendthe evil eye put upon the lot of. them.If tioned then that parts of Cheshire werewas about to hurl his disembowelled setonly they and others of their kidney. would -reported to be bad for wireless reception. throughthewindow whensomethingreduce their filament current by means of I.Ai, whose stationisinthe Wirralsuggested that he should testhis accu- therheostatbeforestartingtheircon- Peninsula, cannot get 2 L 0 at all in themulators-you really can't expect muchdenser -wangling, there would be a great daytime even with five valves; at night-from about 2 volts peace in the land.It is a simple matter time he comes infaintly. ConSidering to increase the resistance a little during that this station is heard in Shetland on searching, which prevents oscillation, and a single valve this is extraordinary, and Speaking of small voltage, though, havethen to brighten the filament once the de- seems to point to the presence of a small youtriedoneofthelow -temperature sired station has been found.Meantime, blind, spot,especiallyasafriendof valves that.are now on the market? Somei, any out -of -work enchanter wants the job I. A.'s, living only two and a half milesof them work on as little as 1.8 volts withof turning Henry and Thomas and Oswald away,receivesthetransmissionsverya current of only ;it of an ampere.In into lop-eared rabbits with pink eyes let strongly with a rectifying valve and twofact their requirements are so small thathim apply without delay to me. note magnifiers.Matters are complicatedthey can be run quitewell from any by the fact that I.A. can receive 2 M Tprimary battery that will give a steady on three valves, whilst friends near bycurrent.The great thing- agailst them is "If you see the prefix micro- tacked on cannot get him at all.-Again, he receives their high initial cost, but this is counter-to any electrical term you know at once both P C G G and F L strongly, thoughbalanced by their long life and the savingthat it means millionth of."So says an friends fail to get the former and receiveinthe cost of recharging batterieS. As American text book, but our microphone weak telephony from the latter.It looksthey work with the filament only justsimply won't believe it ! THERMION. asthough someundergroundvein,ofred-hot, they will outlast three or four metallic ore were cau'sing the waves toordinary valves.The low temperature of A deputation representing the Empire deviate from their courses in curious ways.the ;filament does away with the cracklingPress Union will wait upon,the P.M.G. Will other readers who have come acrossthat is too often associated with a brightlyearly in January to get from him a de- similar instances of .the vagaries of etherglowing valve.For some reason theseclaration of policy regarding the Empire waves please send in brief reports ?Theylow -temperature valves are a little micro -Wireless Chain. 702 DECEMBER 30, 1922 0000000-0<> All About the Valve.-X This Article Concludes the Series Describing the Principles and Action of the Thermionic Valve

F - an alternating current of audible fre-applied to the cylinder, more of the elec-applied through the tapping T to the cylin- quency is supplied to the plate in placetron stream will impinge upon itafterder 3, continuous oscillations may be set of the steady voltage from the D.C. gener-passing through the spaces between theup inthe cylindercircuit,the voltage ator,the stream of C.W. radiationsis spiral electrode. variations arising from each pulse of cur- broken up into audible groups or trains By increasing the positive potential ,onrent being sufficient to maintain the cir- and may be received without heterodyning the cylinder by means of the adjustablecuit in a state of persistent oscillation. ---for example, by a crystal detector. Such tapping Titwill receive an increasing The frequency of these oscillationsis signals are called tonic train.The pitchnumber of electrons, and owing to theiradjusted by means of the inductance L velocity under the added attraction of theand condenser c, and they may be fed to Fig. 18.-The Dynatron or Negative - static field they will strike it with a con- resistance Tube Oscillator. siderable impact. Fig. 19.-Characteristic Curve Electronic Velocity for the Dynatron. Ultimately the velocity may be increased to such an extent that the force of the impactissufficientto"knockoff" secondary electrons from the substance of the cylinder itself.These secondary elec- trons will thereupon be attracted by the more positive charge on the spiral ele- F ment, and therebywillform a second current flowing from the cylinder 3 to the VOLTAGE APP spiral 2. SPIRAL AN At first only a few of such secondary electrons are liberated, but soon there are as many set free as arc received by the cylinder.In other words, each received electron upon impact liberates a'secondary of the note in the receiving phones corre-electron which passes to the spiral elec-a transmitting aerial A (Fig.i8)in the sponds to the frequency of the alternatingtrode.At this stage no current is beingordinary way. current applied to the plate of the gener-received by the cylinder. The dynatron is a typical example of a ating valve.For long-range transmission If the cylinder potential be still furtherthermionic device possessing a "negative itis usual to employ a number of tube -increased the number of secondary elec-resistance" characteristic.There are many generators connected in parallel. tronsliberated exceedsthe number re-other varieties having this feature, and in ceived-that is, some of the electrons ongeneralallsuch arrangements may be Aledifications of the Valve impactrelease twoor more secondaryutilised to generate continuous electrical There are at present in existence manyelectrons.As a result the cylinder circuitoscillations. D. ALCASE. ingeniousmodificationsofthe three - supplies current to the spiral circuitin- stead of receiving current. electrode tube.These aretoo complex El and varied to be dealt with in the present This is clearly shown in Fig. 19.The article, but it may not be out of place topart A B of the curve represents the increas- referveryshortlytooneremarkableing current in the cylinder circuit.From Amplifying Buzzer variety called the dynatron. B to C shows a lessening of current, until A diagrammatic sketch of the dynat,-onat c as many secondary electrons are re- Tones is shown in Fig. x8.It consists of a fila- leasedasthereareprimaryelectrons mentt, surrounded by a spiral wire 2,received, and there is zero current in the tvhich in this case forms the anode andcylinder circuit. WHEN making detector adjustment carries a high voltage from the battery 4. From c to D the number of secondary tests, ordinary magnetic buzzers are Surrounding both these is a third electrodeelectrons liberated continues toincreasegenerallyused. Althoughquitecon- consisting of the metal cylinder 3 contain-and the reverse current grows in value.venient, the faint tone emitted is not as ing in its external circuit a condenser CThe point D is finally reached, however,desirable 'a signal as could be wished for. and inductance L., which determine theat which the potential of the cylinder so The tone can be raised by simply plac- frequency oftheoscillationsgenerated.closely approaches that of the spiral thating tightly -folded strips of paper between The three elements are enclosed in anthe number of secondary electrons lost bythe magnet core and armature and between evacuated globe.The potentialofthethecylinderagainbeginstodecrease,the armature and contact spring. The cylinder 3 is derived from a tapping pointas thereis no longer a sufficientstaticrequisite thickness of paper may be deter- on the battery 4. attractiontowardsthespiralelement.mined by experiment. As there is a high positive potential onThis process continues until, at the point Instead of the paper, rubber bands may the spiral 2 there will be a considerableE, the number of secondary electrons whichbe used if they are wound tightly round flow of electrons from the filament to theleave the cylinder and do not return hasthe buzzer in such a manner as to occupy spiral.If the cylinder is kept at the sameagain become equaltothe number ofthe same position as the paper. potential as the filament practically noneprimary electrons received, and the net In further adjusting the buzzer for a of the electron stream will reach it.If, current is again zero. higher tone, the contact screw must' also however.asmallpositivepotentialis By suitably adjusting the initial voltagebe regulated.-Radio Digest. DECEMBER 30, 1922 703 ntattur VisvitsS 0 A Page in Holiday Mood

"Blenny acquiring his first car he developed bed- The thing howled again. sores on his back.He diaboloed most of "If this was anybody else'sset," said IF there is one thing more than anotherMrs. Blenny's best china into the ashpit,Blenny wildly, "I'd ...saythat the aerial Iadmire about Blenny itisthefineand pogoed through the nursery floor. wasn't connected." fresh enthusiasm with which he greets the You will not be surprised then if I tell "Is yours, dear ?" asked Mrs. Blenny. advent of any new hobby.When theyou that when I boarded the five -forty-five"The window cleanerswere here to -day." hand camera first made its appearance hea few nights ago I found Blenny immersed With a groan Blenny flung open the became oneofthepioneersofsemi - in a work entitled "The Ether's Wondrousfrench windows and strode out into the libellousportraiture,and many ofhisWaves" or something of that kind. night... . efforts are still unsurpassed as trick -takers He looked up asI entered and began He sat down once more to the set, mov- when ourlittlecircleindulgesintheimmediately to attempt tofire me withing things feverishly about. joyous game of photo -bridge. enthusiasm for his newest love.Had I a Suddenly the horn began to pipe like a With bicycles, motor -cycles and cars it set ?No ?Then I was missing the mostcanary. wasjustthesame. When thesafetysplendid kind of entertainment that there "Here it is," cried Blenny. bicycle arrived Blenny discarded his bone -had ever been. "Is that the concert ?" I asked. shaker and demonstrated the wonders of As the train slowed down he urged me "No, the carrier -wave, you idiot.Now thenew machinebeforeanadmiringto come in that very evening to hear mywe'll see." group of friends.His disappearance intofirstwireless concert.Knowing thatit The chirpings grew shriller and yet more the nettlebed and the subsequent lament,would have to be done sooner or later, Ishrill,thensettleddown toa hoarse which made thefinest outbursts of the accepted. rasping. Greek tragedians seem but poor,feeble When I entered Mrs. Blenny's drawing - Then the thing found voice. things, are still remembered.And thereroom after dinner I found that the attack "Hullo, hullo, hulro!" it said. was the adventure with the little pigs inof wirelessmania was more acute even than " There we are," said Blenny, beaming. the narrow country lane.He was for- Ihad atfirst suspected. The polished . .2 L 0 speaking," the voice con- tunate, we told him, in choosing animalssurface of her best table was covered withtinued. "We are now closingdown. so well upholstered-might they not havean array of queer things, some with littleGood night, everybody." been goats? knobs for tuning, and others that shut up He pitched Mrs. Blenny out of trailers, * - * or extended like telescopes.The name This is almost a true story.Let me upset her in side cars, and left the pairwireless seemed a misnomer, for between of them stranded miles from anywhere. make its veracity perfect.It was I who the instruments lay one of the most fascin-enacted the part of Blenny. H. R. His motor -cycles could be counted on toating entanglements that I have ever seen. convert themselves into the push varietyThe room was strewn with batteries, coils, on thehottestofdays. Shortlyafterbits of wire and miscellaneous tools. Blenny moved to the table and turned An Amateur's A.B.C. on a row of quite pretty little lights.TheyA is for AERIAL, ever so high. were not, he informed me rather testily inB is for BATTERY, usually dry. reply to my inquiry, the footlights.HeC forCONDENSER, whichstoresup a began to twiddle the knobs and to push charge. thingsinandout. HisbrowgrewD the DETECTOR, finds signals at large. wrinkled. HemadelittleimpatientE is for EBONITE, good as a base. noises from time to time.The set madeF for the FORMER, each turn in its place. none. G is for GRID -LEAK, 2 megohms or so. He twiddled something else, and the cryH isforHOLDER,whosefunctionyou of the amorous tomcat filled the room. know. "Splendid!" Icried." Ilove animalI for INDUCTANCE, to tune in the set. imitators. Ido hope he'lldo thesea-j for the JAMMING we usually get. lion-through a lamp glass, you know." K for the KEY with a delicate touch. Blenny explained,alittlewearilyIL for the LEADERS -Who teach us so much. thought, that this was not really an itemM for MARCONI, the man of the year. of the programme.It was merely mis-N is for NAUEN, whose signals we hear. behaviour on the part of the set.If youO is for ORA, its value well known. letitcontinue you were liable to haveP is for PARIS, heard clear in the, phone. your licence endorsed for furious howlingQ is the QUESTION we ask you to state. or something ofthatkind. Ido notR the REPLY at the earliest date. wonder. S for the SPARK, that is often so clear. He fiddled with something else.ThereT for the TELEPHONE, held to the ear. was another howl, louder and more melan-U for UNITED, by wireless speech. choly than the first."Must be the thing- for the VALVE, that has brought it in mejig 'that's wrong," he sighed."We'll reach. see." W for WAVE -LENGTH, on which the signal's He laboriously disembowelled one of his sent. contraptions with a screwdriver and a pairX is for X's; we all know what is meant! Something New in Fancy Dress Costumes. of pliers, but found it all as it should be.Y is for something that's not seen in the The thingmebob and the what's its name set; The photograph shows Mr. H. V. Batton, Hamp- stead,as"AmateurWireless." The costume were also above reproach.He replacedZ is another one, I haven't found it yet gained him the first prize. his bits and pieces and tried once more. VECTOR, ,entateur Wireless 704 0 ..... <>00<>"JOC>O<><>'-',,,>< A Complete Valve Set for 4

Fig. 1.-Single Valve Receiving Circait. Fig. 1

MANY amateurs, while fully realising 6. High-tension supply... 0 40 capacity across TI and T2, but if A and (. the many advantagesof a valve 7. Phones ... 1 12 6 be rotated through iSodeg.,A becomes over a crystal receiver, are deterred from opposite to D, and C opposite to B, and a adoptingtheformer byreasonofits 319 6 condenser is formed, since A is connected greaterexpense.Itishoped thatthis to one terminal ,and D to the other.By article may be useful to such in indicating Aerial and Earth rotatingtheplates A and cvarious how a complete valveset may be con- s.d. capacities may be obtained. structedata comparatively low figure. ilb.(about 14o ft.) No.IS s.w.G. A simplevariable condenser onthis This set is built on the " unit " system, so bare copper wire ... 2 0 principle cao easily be constructed.A box that from time to time improvements may 4 reel insulators I 4 4 in. by 4 in.' by Iin. should be made out be made in one component without inter - 9 in. thick rubber tubing for lead-ino 4 of cigar -box wood, and to the under side of the top two pieces of tinfoil (such as is used for wrapping chocolates, etc.), should be attached by means of shellac varnish. Ti Ordinary bare copper wire makes a very The shape of thetinfoilisshownin goodaerial.Stranded wireisstronger Fig. 3.Two tags protrude through which but something of a luxury.A single -wire two terminals pass.A piece of thin mica aerial is easier to erect than a double one, about 0.004 in. thick is then placed over and is preferable in every way if the full length can be obtained (too ft., including Fig. 2 Fig. 4 lead-in). Theaerialmaybe slung between two chimney -stacks and should be as high as possible, one end being led in through the rubber tube insulationina 14-- 4" hole in the framework of the window.To T- ensure good insulation two insulators of the reel type are recommended at each end of the aerial:The earth -lead should be as short as possible and should be soldered to a water -pipe connected directly with the Fig 3 main (not to a cistern).Some of the wire Figs.2,3 and4.-Constructional left over frOm the aerial may be used for Details of Aerial Tuning Condenser. this purpose.If a water -pipe is not avail- able plates may be sunk into the ground and the earth -lead attached thereto. 'mingwiththeothers,andadditional amplifiers may be added at will without Aerial Tuning Condenser any internal alterations to the existing set. s.d. 0 Fig. 1 shows a simple valve receiver, Knob and pointer w ith set screw and the dotted lines divide it up into seven Fig. 5.-A Simple Form of Aerial components, eachofwhich willbe 2 Terminals 6 Tuning Inductance and Reactance. described -separately.The followinglist will give some ideaof the costofthe 2 0 material for each component : the tinfoil, as shown by the dotted line. s. d. Four semicircular plates, A B C D, are This may be obtained from the mica sup- I. Aerial and earth 3 8 arranged as shown in Fig. 2,A and C are plied by ironmongers for oilstoves.It z. Aerial tuning condenser o 2 o insulatedfromoneanotherandare may be split by burring over the edge and 3. Aerial tuning inductance and mounted together ro that they can rotate insertingthefinger -nail,and thepiece reactance ... 0 5 4 about 0, and the plates AB and CD are used should be the thickness of this paper. 4. Valve panel and valve(15s.) 1 5 o connected by two flexible wires.In the A piece of cigar -box wood should then be 5. Low-tension supply ... 0 7 0 positionshownthereisanegligible cut into a circle of V.I. in. diameter and a <>0.00000< iJ ...... 705 Ontaieur Vdess

Specification Aerial Aerial Tuning Condenser AerialTuning Inductance and Reactance Valve Panel, Valve Batteries, Telephones

.1/4, Ins:de of Valve Panel. 71-- 5"----01 Fig. 7:- BALM VIEW .- FRONT VIEW. Details of Valve Panel.

al -in.centreholedrilled,twosmall a nut placed on each side of the bridge to but itis less expensive and simpler for a countersunkholes being made ateach -- prevent the spindle rotating without the beginner. Telephonycanliereceived side of this.Two semicircles of tinfoil, disc.The knob may then be attached to quite satisfactorily. in. radius, should then be -cut out and the other end of the spindle.Each of the shellacked to the disc of wood on the side pieces of tinfoil on the rotating discis Valve Panel on which the holes are countersunk, the connected to one of the pieces fixed to the s.d. semicircles being separated by jin., as in top by means of a spiral coil of No. 28 piece of ebonite about 5 in. by the case of the tinfoil -fixed to the top of d.c.c. copper wire.. 8% in. ... 36 the box.A screw is then pushed through A condenser such as described has been 4 valve sockets 1 0 the tinfoil covering each of the counter- used with very satisfactory results and was ebonite knob with pointer and- set

sunk holes, and screwed rightintothe foundtohave a maximum capacity of screw . . 1 0 wood, so that it protrudes at the other side, 0.00035 mfd.Thisvalueissomewhat and the flat head of the screw is below the small, but the maximum capacity can be surface of the tinfoil (Fig. 4).Contact- is increased if desired by providing one or thus made between the brass screw and the morefixedcondensers of about 0.00035 tinfoil.On the other side of the disc a mfd. (such as used in the valve panel), smallbrass bridgeisplacedoverthe which niay be placed in parallel with the L centre hole with a h -in. hole drilled in it. variable condenser by means of a plug or 4 $cREws switch. Figs. 9 and 10.-Formers for Rheostat. Aerial Tuning Inductance and Reactance 066" s.d

lb.:No. 28 d.c.c, copper wire 4 4 4 terminals Fig. 6.-Valve- Fig.8.-Setting- For thosejust commencing touse a socket Mount- out Panelfor valve set it is a good Plan to make a very -g. Valve -sockets. simple form of A.T.I. and reactance. A number of coils of the slab and basket type should be made from No. 28 d.c.c. wire.One of the coils may be used as a reactance and another_ for the A.T.I., and coupling produced by resting one flat on Fig. 11.-Filament Rheostat. the table and sliding the other over the top.Large wave -lengths may be obtained piece of mica o6 Fig. 12. Details of by connecting two of the larger coilsin 1 ihment Rheostat. series with each other to form the A.T.I. 10 terminals No. 4 B.A. ... 2 6 An improvement is shown in the photo- cigar -box (about S in. by 5 in. by graph (Fig.5),where the coils may be 2in.) o moved about on a horizontal spindle, the 1 reel of flower wire ... o upper spindle beinga holder for spare Piecesofcigar -box,smallbrass coils.The four corner terminals are con- screws, length of H.T: rubber nectedtothe A.T.I.and reactance ter- cable, tinfoil, scrap ebonite, brass The surface of the mica is then rubbed minals ofthevalve panelrespectively. wire, slate pencil, glass tubing 4 with a piece of cloth damped with olive The middle one is usedasa common oil.This is to ensure the smooth working terminal when two of the coils are being 100 of the condenser. connected in series.The ebonite is. not a The disc is placed over the mica with the necessity, for if a piece of dry wood is well The valve panel contains a valve holder, tinfoil side next toit, and _a short h -in. treated with shellac varnish it may be dis- filament rheostat, grid leak and condenser, spindle screw at one end is placed, through pensed with.It is not suggested that this and telephone condenser.These may all the centre hole of the top of the disc and is as good as the more elaborate tuners, he lociught or made at home. entattur Wireless DECEMBER 30, 1922 The valve holder is made by fixing the www.... 0 four valve sockets to the ebonite panel, as shown in Figs. 6 and 7.The panel CORRESPONDENCE should be drilled, as shown in Fig. 8, the ebonite being marked off with the hole A Radiograms in the position shown in Fig. 7.If there Fading isany serious difficulty in inserting the ...... SIR,-Ihavereadwithinterestthe vallie it is a good plan to slacken the nuts T is suggested that a band of amateursarticle in a recent issue on "Fading Sig- of the sockets, then insert the valve and Ishould be formed in Glasgow with thenals," and suggest that experiments should tighten them up again.The valve shouldobject of searching out the operators ofbe carried out.By obtaining the co-opera- then take in and out quite easily; if not,valve sets who are allowing them to inter-tion of your readers and choosing a cer- the holes in the ebonite should be slightlyfere with the reception of their neighbours.tain evening (correct time to be taken as enlarged. Like other congested areas Glasgow suffersthe first stroke of the hour from Marconi For the filament rheostat a former aboutconsiderablyfromthisnuisance;oneHouse) observations could be readily made 2 in. in diameter is required to be turned,prominent experimenter has offeredthe and results forwarded to you by the ob- as shown in Fig. 9.If a lathe is not avail-use of a direction finder and a motor carservers. The details of organisation,I able a good former may easily be made byin tracking down the offenders. feel sure, are best left to you, although I cutting out four circles of cigar -box wood 1. am willing to help in compiling the data with a fretsaw, two 2 in. in. diameter and into a form for easy analysis.-H. V. M. two 2 in. in diameter.These should be A directional wireless station has been(Plumstead). erected at Hallo, in Sweden, with the call fixed together, as shown in Fig.to. A [We shall be gladofother readers' length of rubber high-tension cable (suchlettersS A M. Thisstationwillgiveopinions.-ED.] as is used to connect the sparking plug ofships calling within 15o miles their bear- ing.The charge for each bearing given is an engine to the magneto) is then cut so 5 H V and 5 Z that it will almost reach round the circum-placed at 5s. 9d. ill III SIR.,-Can any of your readers inform ferenceoftheformer.Roundthisis II me who 5 H Y and5 H Z are ? Ihave coiled the flower wire, each turn being The British Broadcasting Company washeard very loud telephony from both these wound as closely as possible to its neigh-duly registered as a limited company onstations when I have been listening to the bour without touchingit.The winding December isth. Birmingham Broadcasting Station.Some- should not be taken right to the end of one has suggested that 5 H Y is a station the cable in one case, but to within about on one of the islands off the extreme north 3A in.oftheend.The ends may be An agreement has been made by the British Broadcasting Co., Ltd.with thecoastofScotland. Isthisso ?-S. W. secured by slipping them underneath the (London). previous turn.The H.T. cableisthenfollowing press agencies :Reuter's,the mounted ontheformer,asshownin Press Association, the Central News and Fig.II, being fixed by attaching the twothe Exchange Telegraph Company for the PCGO on the Valve ends of the inner stranded suppleach dayof a summary ofthe SIR,-I thinkit may interest some of to screws in the former. world's news. your readers to hear that P C G G was re- A short length of brass rod about Nt in. U ceived by me on Sunday 3/12/22 using the in diameter screwed at one endisre- Itis probable that the Savoy Havanasingle -valvedetector panel describedin the "Work" Handbook.The music came quired this is inserted through a hole in theBand willplaypartoftheChristmas centre of the former and the ebonite knobbroadcast programmes, so that the dancersin quite clearly, although it was difficult attached to the unscrewed end by meansat the Savoy will have the novel experi-to follow the announcements, only words of its set screw.A contact arm is thenence of listening to their usual orchestrahere and there coming in loud enough to required, and may be made out of a pieceby wireless. hear. of hard, springy brass or copper, or better, In my panelI am using a grid -leak phosphor -bronzestrip. Thisshouldbe consisting of a piece of slate pencil with about y4.in. by 134 in., and should have a A Committee of the Cabinet has beengraphite lines, and it is placed across from hole drilled in one end, so as to be attachedset up for the purpose of once again goingthe grid condenser (valve side) to the posi- to the brass spindle between the two nuts.into the question of the Imperial wirelesstive side of the filament.I find this an The other end is bent so as to make con-chain. improvement on the position acrossthe tact (Fig. 12) with the flower wire.Two grid condenser.My aerial is roo ft.(in- small screws are then fixed to the former At the general meeting of the Gramo-cluding lead-in), single wire, only 20 ft. to serve as stops, for the moving arm, andphone Company, Ltd., held recently, theabove ground, but a small indoor aerial to one of these the end of the flower wirechairman explained that wireless telephonywas also connected up to the A.T.I. on from the end which is wound to the endand broadcasting in its present state wasthe above occasion.An "Ora" valve was of the H.T. cable should be soldered.Thenot likely to affect the company's business.used, and the fine tuning was done by the rheostat is then ready for mounting on the filamentresistance.-H.C.B.(Forest ebonitepanel. It may befixed bya Hill). 5 B countersunk wood -screw, a small tapered A steam locomotive was recently hole being first made in the ebonite, but sue - SIR,-I should like to register a protest cessfully controlled by wireless in not right through.An ordinary counter-America. through the medium of your paper of the sunk bolt and nut may be used, but the use of my call -sign, 5 G B, being made by wood -screw method avoids showing any II some other amateur in Liverpool or dis- bolt heads on the top side of the panel. A new Belgian wireless company hastrict.Naturally, I have strong objections A photograph of the near side of thebeen formed under the title of La Societe tosuch a practice.-L. HUMPHAIES, 61, valve panel is shown by Fig. 13. Beige Radio Electrique. Geraint Street, Liverpool. (To Ire concluded) The Prince of Wales listened in to a "Wireless Telegraphy /Our gratis list of Techni- wireless message broadcast from 2 L 0 on :: and Telephony" :: cal Books contains Dec. 13 by Sir William Noble whilst he The most Practical Handbook for the particulars of this was on a visit to Devonshire House. Amateur.The priceis 1/6 net. splendid little work. DECEMBER 30, 1922 707 Manchester Broadcasting Station

THE 'Manchester Broadcasting Station commutator. Inthiscaseitisveryare necessary to retain all the real brilliance I(2 Z Y) hasestablished a -reputation efficiently done by passingthecurrentof tone whilst cutting out echo.A great for the excellence of both its transmissionthrough a filter circuit consisting of in -deal of experimental work has had to be and its programmes. done to determine both the right size for the chamber and the most suitable material A fortnight ago the MetropolitanVickers The Station Electrical Co., Ltd., entertained a party of for the draping. The station issituated in the research journalists at Trafford Park, Manchester. A switchboard (to be seen on the left department buildings of the works of the Among the party was a representative of sideofthephotograph)connectsthe Metropolitan Vickers Electrical Company, " Amateur Wireless."Here is his descrip- various microphones with the transmitting Ltd.,Trafford Park,Manchester. This tion of the broadcasting station and of the set.All the circuits are run in separate small experimental stationat Hale,six company is technically very closely asso- miles distant. cables to avoid inductive effects.On the ciated with the Westinghouse Electrical panelisa lamp which is used for sig- and Manufacturing Company, who were nalling that the transmitting set is work- the pioneers of broadcasting in the Unitedductancesinseries,shuntedwithcon-ing, and when the lamp is glowing no States, and has had atitsdisposal thedensers.Fig.r shows the two generatorssounds must be made other than those to *hole of the experience and experimentaltogether with the control panel. be transmitted. work of that company. Since its inception 2 Z V has been work-Transmitter Panel Musical Equipment ing on Soo watts, but by the time this de- The transmitter panel, shown in Fig, 2, The equipment of the studio consists of scription of the plant and methods of thewas installed by the Radio Communica-a Steinway grand piano to which can be

Fig. 1.-Generators and Control Plant. Fig. 2.-Transmitter Panel. station is in print it should be using thetions Company of London, and employsfitted a Welte player attachment.In addi- full 1,50o watts for which itis licensed.three Mul lard 0-50ovalves. The high-tion,thereisan Edison diamond -disc It started on the lower power in order thattensiondirect -currentsupplyat5,000gramophone and an /Eolian"Vocalion the many problems to be solved shouldvoltsissupplieddirecttotheplates,Graduola"gramophone. The ordinary not be unduly complicated. and a suitable protective gear is provideddesk telephone on the table beneath the to protect the generating set against shortcontrol switches is used for announcing the Power circuits.The filaments of the transmittingitems and for the broadcasting of news. The power for the' transmitting setis valves are heated from a 3o -volt battery. suppliedbyasmallso -cycle3 -phase The character of the modulation given byMicrophones generatorintheworkspower -house.the transmitting set can be checked in the The speech and music to be broadcast is This delivers 440 volts and is employed tosmalltransmission room by meansofpicked up by microphones supported on drive a triple set consisting of an induc-eithera .setof headphones oraloudconvenientadjustablestands. Oneof tionmotor,high-tensiongenerator andspeaker., these stands, with the microphone hanging exciter supplied by Newton Bros., Derby. from it, is seen on the right of the picture. The high-tension generator is rated at 2.5Studio The sound energy, having been translated kw. at 5,000 volts and runs at 1,5oo revo- The studio, in which are given the con-into electrical energy by the mirophones; lutions per minute. Two of these sets arecerts that are broadcasted, is a draped -offis given preliminary amplification through installed, and a complete changeover ofportion of a spacious room adjoining thethree to five valves before it is passed to drive and supply can be effected in emer-transmission room. A photograph of thisthe transmitting set. gency by throwing- a single switch fromis shown' on the cover.It is arranged to The placing of the microphones in rela- one side to the other. One of the problemsgive the utmost acoustic efficiency and totion to the performers is a matter in which of transmission is that of getting rid ofeliminate all resonance and echo.constant experithental work is being car- the noises, or "ripple," caused by the veryResonance is not desirable, and the car-ried out.The distance depends entirely rapid make -and -breakofthegeneratorpeting of the floor and draping of the roomon the character of the sounds that are to (I mateur Wireless 708 DECEMBER 30, 1922 be transmitted, and the whole question is one of considerable difficulty.The choos-Improved Broadcasting ing of suitable performers is also of more difficultythan outsiders would suppose. Service CLUB DOINGS Some voices and instruments that are ex- WHEN the regular service of broad- casting cellent for chamber or concert -hall work wasfirstbegunitwas Thames ValleyRadio and PhysicalAssociation. transmit very badly, whilst others that areunderstood, of course, that the broadcasts Hon. Sec.-E. A. ROGERS, 17, Leinster Avenue, East Sheen, S.W.14. not nearly so successful in the ordinarywere to be of an improvised andtern-THE secretary will be pleased to givefull particu- - way transmit very well.In this matterporary nature, until such time as detailedlars of the above society toall interested. unceasing experimental work is being donearrangementscouldbe made andthe Croydon Wireless and Physical Society. at all the other broadcasting stations. BritishBroadcastingCo.was formallyRon. Sec.-B.CLAPP, Meadmoor, Brighton Road, Purley. In the case of singers the problem is notregistered. Thislatterevent has nowA most interesting lecture was delivered by L.F. only one of quality of voice.The ideal isbeen accomplished and we are informedFogarty on "Different Methods of Charging Accu- mulatorsfromA.C. The lecturewasillustrated to find vocalists and speakers who can, sothat at a very early date the programmes by a number of very clear drawings depicting the different methods, and was demonstrated by a large to Speak, project their personality into theof the stations now operating will be con-number of instruments including electrolytic, vibrat- microphone.Such people may or may notsiderably extended. Permanent stations ingreed, and vacuum tube rectification,by which Mr. Fogarty charged accumulators at various rates be rare; the difficulty is to find them.Theareto take the place of the temporaryup to 5 amperes. quality is elusive, but when itis found itones with, it is hoped, a general all-round Birmingham Experimental Wireless Club. is welcomed by thousands of listeners -in.improvement. StationsatNewcastle, Hon. Sec.-A. L. LANCASTER, Lancaster Bros., Shad - well Street, Birmingham. The "Uncle Humpty-Dumpty" who tellsCardiff and Glasgow are to begin workingDIE secretary will be glad to furnish particulars to :he children's storiesat Manchester isaat an early date.In a recent interview intending members. caseinpoint.Already heis"snowedSir \Villiam Noble, chairman of the broad - Redditch and District Radio Society. under" with letters from little friends hecasting committee, said, "May I ask the lion.Sec.-A. W. REEVES, The Elms, Alvechurch, near Redditch. has made.Some of the letters have conicpublic not to judge of broadcast by the PARTICULARS regarding membership may be obtained from places over 300 miles from :Traffordpresentserviceat thethreetemporary from the secretary. Park. stations." Actualdetailsofthepro - Bath Radio Club. The aerial used by 2 Z Y. is of the cagegrammes are not yet available, but theyHon. Sec.-G. J. CURTIS, 6, Pierrepont Street, Bath. APPLICATION formembershipto be madetothe. type, consisting of six- wires supported bywillincludehigh-grade concerts,three secretary. hoops. news summaries from four British press The average height is 16o ft. Ashton-under-Lyne and District Radio Society. In connection with the Trafford Parkagencies, and three daily weather reports. Hon. Sec.-J. H. MARSHALL, 22, Warrington Street, station is a small experimental station at Ashton-under-Lyne.Ovx/Nrs".rw %."./WO PARTICULARS of the above newly -formed society can Hale.This is used for both transmission be obtained from the secretary. experiments and as a "control" for the BROADCAST TELEPHONY Some of these transmissions are commercial Fulham and Putney Radio Society. quality of the transmission from the mainor official.Wave -lengths and times are liable Hon. Sec.-J. WRIGHT ,DEWHURST,52,North End station.It has a small transmitting set Road, West Kensington, W.I.4. to alteration without notice. ON Dec. 1 Mr. Houstoun gave iris experiences and oftoowatts,andis verycompletely London B.B.C. Station (2. L 0), 369 metres.described some wiringexperiments he had made with the four -electrode valve.Mr. Calver described equipped for listening -in.The aerial atDaily, usually 7 p.m. to so p.m. . . the results of trials he had made of various Arm - Hale is15oft.long, triple wire,' and is ManchesterB.B.C.Station(2 Z Y),385 strongcircuitsaspublished, andalso mentioned metres.Daily, 4.3o p.m. to 5 p.m., concert;that he had wired up a new circuitwhich gave placed at a height of 75 ft.Most reception6 p.m. and 6.15 p.m.,kiddies' corner; 6.3ogood results. experiments, however, are done on a small p.m. to7p.m.,reproducing -pianorecital; West LondonWireless and Experimental subsidiary aerial within the limits set by7 p.m., news bulletin; 8 p.m.to9.to p.m., Association. the Post Office for those taking out broad-concert ;9.15 p.m., second news bulletin ;9.30 Hon. Sec.-H. W. COTTON, 19, Bushey Road, Har- p.m. to to p.m., miscellaneous concert. lington. cast reception permits. 425 AT a meeting held on Nov. 24 Mr. C.A.Hillyer Birmingham B.B.C. Station(2 W P), gavePartIIofhispaperentitled".Electrical The outstanding feature of 2 Z Y is the metres. Weekdays,6.30 p.m.to6.i5p.m., Measuring Instruments," and everyone was deeply enthusiasm of all those connected with it.children's stories; 7 p.m., news bulletin; 7.15interested both withthe data placed before them and the manner in which the paper was rendered. They are just as "wireless -mad" as theP.m. to 8.30 p.m., concert ; 9 p.m. to 9.45 P.m.,The secretary will have much pleasure in replying concert ;9.45 p.m., second news bulletin.Sun- toinquiriesrespectingtheobjects and terms.of many thousands who nightly listen to theiril,tys, 8 p.m., news bulletin ;8.15 p.m. to 9.45 subscriptionto this association. work. E. L. pm., concertsecond; 9.45 p.m., news bulletin. Croydon (C L I)), 900 metres. Daily. Chesterfield andDistrict Radio Society. O C. Hon. Sec.-J. DANBIDGE, Writtle(2. H'I'), 4(x) metres. Tuesdays, THE secretary will be pleased to hear from persons. 8 intending to become members of the above society. Wireless Handbook and Diary,-A neat Tower -(FL),2,600metres. Daily, pocket diaryforwirelessamateurs has 5.20 p.m. to 7 p.m. Wolverhampton and District Wireless Society. been published by the Radio Press, Ltd., The Hague (P C G G), 1,o85 metres.Sun- lion.Sec.-J.A.H.DEVEY, 232, Great Brickkiln Street, Wolverhampton. of DevereuxCourt,Strand,LOndon, days, 3p.111.to5 p.m. In addition to the usual featuresDec.Rome (I C D), 3,2oo 13 metres. tookDaily, the 10 forma.m.. 'FitE of weeklyan exhibition meeting . of the above of wirelesssociety held on W.C.2. Konigswusterhausen(LP), 2,800metres: sets, the chief object of the meeting being to show of.adiary a considerable amount of in- thevariousefforts made by members atbuilding Daily, 4 p.m. to 5.30 p.m. their own sets.The exhibits, which ranged from formation and data of value tothe ex- Amsterdam (P C A),1,800 metres.Daily,the simplest formofcrystalsetto the elabOrate perimenter is given.Its price is 25. 6d. 1.10 p.m. valve panel, were distinctly creditable.At intervals Haren (0 P V H), 900 metres.Daily, everythose present were entertained by the Birmingham hour fromi 1.2o a.m. to 4.2o p.m. broadcasting items, a loud speaker being in use. "Notes on Supersensitive Microphones" Leeds and District Amateur Wireless Society. isthetitleof anarticlethatwillbe CATALOGUES RECEIVED _ Hon.Sec.-D. E. PETTIGREW, 37, Mexborough Avenue, Chapeltown Road, Leeds. ofspecialinteresttowireless amateurs Sterling Telephone and Electric Co., Ltd.-AN exhibition of apparatus and demonstration of in the present issue of "Work."Other Loud Speakers and Power Amplifiers. wireless telephony was held on Dec.r.Telephony G. Z. Auckland & Son.-Component Parts. transmissions 'were received from Mr. H. F. Yard - articlesinclude :"SimpleRepairsto Wireless Supplies Co.-Valve Sets and ley'sexperimentalstation2 L B On 400metres. Broadcast itemswerealsoreceived,During the Blowlam,ps" "A Pairof Wrought -ironCry stophone Complete Outfits. course of the exhibition numerous lectures were de - Fire -dogs," "Finding Steam - engine Saxonia Electrical Wire Co.-Flexible Wires,livered by members of the society and others. Horse -power,'.'"Keeping a Small GateCables, Cords, etc. At a general meeting held on Dec. 8 the chairman MedicalSupplyAssociation.-Crystaland calledupon thepresidenttogivealecture and inHot demonstration of recording apparatus.The presi- Shut,""Spoons etc.,Fusible Valve Sets and Component Piats. dent outlined the work done on recording devices. W7ater," "TheSaltosphere. .A Sus- Radiophones,Ltd.-ValveSetsandC'orn- paying particularattentiontotuned trigger valve relays. The wholesystemofreceptionusinga pended Cork Ball."(illustrated), "Sonicportent Parts. single valve receiver with a tuner trigger relay was NoveltiesinMetal "(illustrated),"A T.V.ElectricalandWirelessSupplies.-clearly described, and with the aid of diagrams the Component Parts. action of the magnetic relay in controlling the valve T abl e -chair." Fully' illustrated,price Jeary ElectricalCo.,Ltd.-Valve Sets and relayoscillationsdescribed.The lecturer showed threepence, weekly. Component Parts. (Continued on page 710) DECEMBER 30, 1922 709 QmateurWit-des:5 El ...... 41. 4...... 4. 4. 4, 4. 4. 411. 4. 4. 4. 4. 4. 4, 4. 41. 4, 4, 4. 4. 4. 411. 41.41111. 411. 4.

How the Telephone Receiver Works I [pao-(--4.4, 4. 411. 41. 4, 4, ..... 41...... 0-0.0C<>0.0000.00.00000.0 ...... o<=L1 THERE are a largenumber of ceased to flow the magnetic field vanished.transmitter flow round the coil the mag- beginners who, although making fre-Here then wasa means of creatinga neticeffectbeing madeintermittently quent,ifnot daily,use of that humblemagnet at will.It was then found thatgreater orless,the diaphragm will be instrument the telephone receiver in someby making the wire into the form, of amade to vibrate between the three dotted lines as shown in Fig.2. The vibrations thusproducedwillcorrespondexactly with the vibrations originally set up at the - ...... - transmitting end. 'NORMAL The type of telephone receiver used in POSiTION Of wireless is called the watch receiver, and DIAPHRAGM although constructedina slightlydif- COIL ferent manner,itworks in exactly the same way.Figs. 3 and 4 'show sections of a watch receiver. R. A. F. BAR MAGNET <:).0-00E Fig. 2. -Working Princ ple of Telephon- Receiver. 3 Valve made from Motor -lamp Bulb Fig. 1. -The Bell -type Rececl 411. 00

Tuning Devices. provide a means of obtaining very fine tuning Portsmouth andDistrict Amateur Wireless Q.-Will you explain the respective advan-,witha minimum'of -adjustments.They have `:, Association. llon. Sec.S. Hogg, tj, Pelham Road, Soutbse6.. the drawback, however, that selectivity'of . tages and disadvantages of the many types of inquiries may be senttothesecretary, who tuning devices at present, in use, with theirreception cannot be obtained ;with vario-would specially welcome new members. suitability both for crystal and valve appara-couplers the range of wave -lengths is very tus.-H. C. (London) (5,997). limited unless a massive instrument is con- ProposedLee and District Amateur Wireless Society. A.-There are various kinds of inductancesstrUcted.-L.C. Wm,all persons interested communicate wills A. H. Kidd," Woodlands,"39,Burnt Ash Road,Lee, for tuning purposes all of which should have S.E.12, with a viewtotire formation of the above a variable condenser in conjunction with them RemovingEnamelfrom Wire.-There society. for fine tuning.Briefly slab, honeycomb and is difficultyin iscraping off enamel the basket coils have the 'advantage of giving SunderlandWireless and ScientificAssociation. the required inductance and yet being verywithout breaking the wire.One way of Hon. Sec.-A. RICHARDSON, Westtfield House, Sun- One removing the enamel is to pass the wire derland. compact and simple ofconstruction. ON Dec. 16 Mr. A.T.C. Danis, of Marconi's Wire- great disadvantage with this type of coil isover a bunsen gas flame several times,less Telegraph Co., lectured on " Wireless Direction thatthedifferenceofpotentialbetween Finding.' The lecture was illustrated by excellent until the enamel melts and drops off.If lanternslides. The lecturersaidthat before the neighbouring turns is often greater than isitisimpossibletodothisbecauseof development of the thermionic valve it was not poS- desirable.In the case of cylindrical or single - sible to compress the large aerials then necessary layer coils the difference of potential betweencircumstances;thesameresult, says for direction -finding into the limited space afforded Radio Digest may besecured bydis- byaship. Suchstations inthosedayswere adjacent turns is practically nil, and there is therefore situated in coastal positions.In an early little impedance to current flowing throughsolving the enamel in amyl alcohol. German method a kind of umbrella aerial was em- the wire.The disadvantage of single layer ployed, and a rotary switch was provided whereby coils is, that to receive any high wave -length various portionsof the aerials were used insun - CLUB DOINGS(continued frompage 708) cession.This method was improved upon by using itis necessary to build a large instrument. thenecessityofan' uprighting " magneticrelay two triangular aerials at right angles to one another. Maximum results with minimum selectivity before describing the pointer.A demonstration ofThe bases ofthe two triangles were made toin- are obtained with the single coil tuner.It is theapparatus on viewtookplace,signalsbeing clude respectively two coils whose axes were also at printed up tofifty words a minute. right angles one to the other.A rotating " searCh practically impossible, however, with single - coil," the secondary of the receiving set, was made coil tuners to tune out interference from any Sutton and DistrictWireless Society. toturnwithintheseformercoilsandsogive station near -by and consequently a two coil or maximum and minimum strength ofsignalscorre- Ron.. Sec.,-E. A. PeWELL, Stanley Lodge, Roscberysponding to the direction of the transmitting station. loose -coupled tuner is necessary.This typeRoad, Cheam. . . The advent of the.thermionic valve made it possible of apparatus allows of very tuning ON Thursday,' Dec.14, a successful 'demonstrationfor the two ofwirelessreception wasgiven, and duringthe. "` loop" aerials to be small enough to for any wave -length.Variometers give fineevening over 150 people were able to enjoy musicbe installed upon ships, and the arrangement de- tuning over a limited range of wave -lengthstransmitted fromLondon, Birminghamand. Man-scribed was used extensively by the Marconi Com- without the use Of a tuning condenser and che ster. (Continued on page 714) The Famous"WORK"Handbooks

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This is to announce that on JAN. 15th RADIO PRESS LTD., the well-known publishers cfauthoritativewirelessbooks,will publish a new monthlywireless Magazine entitled : MODERN WIRELESS II- NETT Every reader of "Amateur Wireless" should obtain the brilliant first number. The Magazine is edited by John Scott -Taggart,Ft Inst.P., assistedby E. Redpath, Author of Cassell s "Work" Handbook "Wireless Telegraphy and Telephony," and by Paul D. Tyers, Author of "Construction of Wireless Receiving Apparatus," both well-known contributors to the pages of "Amateur Wireless." Order your copy from your newsagent, bookseller, from a railway bookstall, or direct (1/3 post free) from 1Rat)io pre. 10,,DEVEREUX BUILDINGS, STRAND. LONDON, W.C.2.

" Wemco " Wireless Receiving Sets Specially designed for Broadcasting under Bliesh conditions, and approved by the Postmaster - General. UNIT SYSTEM.

See Postmaster - General's con- ditions,andnotethatthis CrystalDetector orRectifier Panel need not be scrapped at any future date should itbe ....g desired to add High or Low , Frequency Amplification. visor- -...... No.1 (Crystal Detector)SET. £4 15s. Od. Including 4,000 ohm Double Head Gear Receivers. This setissufficienttoreceive (within a range ofabout 20 miles)all concerts, etc., under Broadcasting arrangements. W ithinthehintsofthese wave -lengths (300 to 500 metres)itismore efficientthan similar apparatus which covers 1 an unnecessarily wider range. All prices Include free packing and free delivery in Creat Britain, and provide for Patent Royaliies and Manufacturers' payments to, the British Broadcasting Co. Send us a Post Card and ask for our ListNo. 122 A.W. Manufactured by : WALTERS ELECTRICAL MANUFACTURING CO.) Ltd., Telephone: PARK 653, KENSAL ROAD and CONLAN STREET, LONDON, W.10, ESTABLISHED 1880. INCORPORATED 1907. Manufacturers and Contractors to the Post Office, War Office, Admiralty, etc. etc. Members of the Bri'ish Broadcasting Company. (linatetir Wireless 712 DECEMBER 30, 1922

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Complete Sets of PARTS for Making Variable Condensers E,

REVISED PRICES, without Ebonite EVERYTHING READY TO ASSEMBLE and IA Approx. CONSISTS of the FOLLOWING : CI Capacity in No. of Plates Price Accurate Aluminium Fixed and Moving Vanes, Large and Small Spacer Washers, Centre El Microfarads Square Spindle (Screwed Ends,2 B.A.),3 Side Rods, is Nuts and 22 Brass Washers '0015 85 ,.. 9/- (2 B.A.), Pointer - scale o-r8o, Terminals, 3 Bushes, Spring Coil Washers, Best Quality ' 001 57 6/6 Knob with2B A. Nut in Centre. ALL HIGHEST QUALITY GOODS. ' 00075 43 ..- 5/6 '0005... 29 ... 4/6 PLEASE NOTE '0003 ... 19 ... 3/- DRILLED EBONITE ENDS- . 0002 13 ... 2/3 11- per pair extra 7 Pcstage and Packing, 1/- per set extra.Two Sets, 113.Three Sets, 1/6. ... 2/- Owing to the extraordinary value given in above Condenser Sets, we are compelled to make these charges Vernier 3 ... 1J9 for packing, postage, etc.

ALL the following GOODS POST FREEat theSPECIAL PRICESattached for POST ORDERS Iii If you are not satisfied with value, return goods and we will refund all e6arges Filament Resistances.Most wonderful value in Aerial Wire,722 bare copper, stranded,first Intervalve Transformers (low frequency), high the wireless trade.Each 2/6 and 3/6.By class quality, not a substitute. Price per 11.a./6s.s, tested, and guaranteed 5-1, 14/- each. Post, 3/.and 4/- 100 ft.,2/10. By post, 3/10. By post,15,'-. Smaller size, 10/6; by post, Switch Arms, with polished knob, bushed 2 BA Reel Insulators, 1d. each.Cannot be sent by nut,laminatedblade,spring. coil washer, post. Hertzite Crystal, per piece, according to size, nuts and bush, 1/-,1/6,21- each. By post, 10 mm. Insulating Steering, 6 yds. for 2/2.By 1/3 and 1/6.Cannot send by post. 1/3,1/9,2/-. post, 2/6.12 yds. for 4/-.Bypost,4/6. Crystal Detectors on Ebonite.Simply marvel- Slider and Plunger, 5d.By post, 7d. EboniteDials,with engraved scale 0-180,1/ - lous value.Each 2/6.By post, 3/-.Also Slider Knob, plunger and 13 inrod.The. lot, each. By post, 1/6. Not 3/3; by post, 319. 8d. Cannot be sent by post. - Egg insulators,4 for 9d.; 2. per doz. Fixed Condensers, with terminalson ebonite, Aluminium Vanes, 2 doz. 1,-.By post, 1,'S. sent by post. .0003,.0005,.001,.002,.003,1/e;by post, gross; by post,61-. GridLeak and Condenser, ,.0003,veryhigh 1/9; .o04, 1/9; bypost,2s. War OfficePattern Terminals,complete with quality andappearance,39.By post, 4/3. Oojah Basket Coils, 7 in set, 5/.set.By post, nut and washer, 1/8 doz.By post, 2/2 doz. Inductance Colts Wound Enamel Wire, 12 by 516. Splendid Line In 4,3/-. Not sent by post. Lead.in Tubes, ebonite, brass ends, 9 in.,1/2. 5 -piece Terminals, complete By post1/6. 12 in.. 1/4.By post, 1/8. with nut and washer, good size, 1/- doz. By Filament Resistance, " Thor " pattern, suitable post.1/6. 4/.. Good CondenserKnobs,tapped 2 B.A.,at for one, two or three valve sets, By 2/-doz. By post,2/6. Large Spacer Washers, 3 doz. 9d.By post,1/.. post,fo Knobs, with brass nut (2 B.A.) in centre, high- Small Spacer Washers,'6 doz. By 'post.. 1/4. Terminals, telephone, 1:ghly finished, withnut class quality, 40d. each.By post, 7d.6 for Terminals(verylargt),i'Magnificent-quality, and washer.2/- doz.$y ,post, 2'6. 21-. By post,2/6. aerialand earth,it onipjete ;with 2.nots and WarOfficePatternTerritimals,extraspecial CrystalDetector, cupenclosedwithglass 2 washers(2 stetts),2 fOrBd. By quality,2i6.with nut and m usher, doz. By Ts cover, dustproof,4/6. By post,5/3. post, 1/-. post, WE .BEATCREATION ON PRICES ANDQUALITY.

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EligKrA(a=1K]giTEIlmAKEEIElggCIO DECEMBER 30, 1922 &r Ws IMPORTANT WE HAVE OPENED VERY COMMODIOUS PREMISES AT 54, Gracechurch Street, E.C.3 for the demonstration and saleofalltypes of Wireless Receiving Sets and " Claritone " Loud Speakers. Amateurs and Experimenters willbe able to obtain every part required for any type of Set including ; Transformers, L.F. and H.F. Valves, M.O. and Mullards Headphones, alltypes, all resistances Brass W.O. and TelephonetypeTerminals, Condensers, variable and fixed, all capacities Nuts, Washers, Contact Studs and all other parts Vario-Couplers and Variometers Accumulators Coil -Holders and Coils Dry Batteries Anti -capacity Switches,all types Aerial Wire Rheostats, all types Insulators Radial Switches, 5, 10 and 15 way Hertzite and Galena Crystals Ebonite Valve Holders, Dials, Scales, ether Cotton and other Tubings, all colours parts and in sheet Etc. etc. PRICE LISTON APPLICATION PETTIGREW & MERRIMAN, Ltd., 122.124, Tooley Street, London, E.C.1 Note: 54, Gracechurch Street is a few minutes from Monument, Eastcheap, Bank, Cannon Street & London Bridge TELE. :HOP 134

BROADCASTING RECEPTION SETS One -Valve Set Complete for Working, £7 10s. Passed for DESCRIPTION : Broadcasting Single Valve, mounted on polished Licence G.P.O. On. Ebonite Panel with Variable BATTERIES No. 1038. Condenser,smooth actingresistance, grid leak and Condenser and allterminalsclearly SEtiO FOR engraved inwhite, in CATALOGUE a Mahogany Polished Cabinet 9 in. by 5 in. Batteries by 5 in. £3 15 0 for A TAPPED COIL for wave -lengths up to goo metres with 2 ter- minals for coils for any Valve Sets higherwave - lengths. The coilis enclosed and the tappings are brought out to an S -way switch mounted in the front of the cabinet. 24v. 28v. 32v. ACCESSORIES INCLUDED: Type B.K. Siemens' 54 -volt high-tension .Battery with plugs for altering the voltage 150 Owing to the demand for these batteries, 4 -volt 50 -amp. -hour low-tension Accumulator in all orders will be dealt with in strict rotation. case with carrying strap ...... 140 One pair of Sensitive Headphones of 4,000 ohms Prices approximately oneshilling a volt. resistance...... 1I0 :: Ask for Leaflet 4030 :: One Detecting Valve ...... 150 Total£7100 Otliturib,eECINARICALNY IISLOrRrEADGE Satisfaction Guaranteed or Money Refunded. WIRELESS INSTALLATIONS Ltd. 15, Aldersgate St., London, E.C. CLIFTON JUNCTION, I 219/229, SHAFTESBURY Nr MANCHESTER. I AVENUE, W.C.2. AGENTS WANTED. PRICES AND PARTICULARS ON APPLICATION. nvateur Winless DECEMBER30. 1922 CLUB DOINGS (continued from rage 710) Notice to Advertisers party.The bearings obtained by such apparatus did not give the absolute direction ofthe transmitting ADVERTISEMENT INSTRUCTIONSand station.Thus the latter might equally well be either duenorthor due southofthereceivingstation. copy for" Amateur Wireless should be at the This difficulty bad, however, been overcome by an ingenious arrangement. office by First Post on FRIDAY morn- WIRELESS VALVES West LondonWirelessandExperimental ing at the latest. Association. ITYI'NPI./11N113 Han. Sec. -1-1. W. Corrofc, 19, Bushey Road, Har- lington. ANY' gentleman desiring totake up wireless either PREPAID ADVERTISEMENTS. for experimental work or entertainment ran obtain The Latest Invention.Steam rotaryengine, reg. fullparticularsoftheassociation'sobjects by patent.The finest scientific working steam engine communicating s iththe secretary. ever invented.r s. each, 3 for as. 6d.-Alan Hitcher), Patentee and Manufacturer, Dept. 17. Burnley.[30 r Redditch and District Radio Society. WirelessDealersthroughoutGreatBritainare Hon. Sec.-A. W. REEVES, "The Elms," Alec:church. stronglyadvisedtostockpartsformaking up A PUBLIC demonstration and exhibitionofwireleSs wireless sets. Buy yourpartsdirect from the factory equipment seas held on Dec. 13.The demonstration at wholesale prices.-Newtonia Wireless Factory, 13 was given by Mr. A. W: Reeves and Mr. Entwistle. and15, Whitcomb Street, London, W.C.2. bothofthe'WesternElectricCo. Mr.Entwistle B.A. Screws, Nuts, and Washers, assorted gross, explained the various units and their use in a very as. ;list, ad.-J.H. Bennett, Station Road, Willesden able manner.The Birmingham Concert Party gave Junction. f32 r an excellent programme from Witton, the reception CabinetsandCases,inpolished mahoganyor of which was very much appreciated by the large teak. Quotations per return.-Lancasters, 87, audience. Parade, Birmingham. 133 r Hornsey and District Wireless Society. Han. Sec.-II. DAVY, 134, Inderwick Road, Hornsey. ON Dec. 11 Mr. Fleet gave a demonstration with a WIRELESS BARGAINS. 3 -valve amplifier of his own construction.The re- ALL-SRITISH. ception of musical items from 2 L 0 and 2 \V P were PHONES 21/- SUPERSENSITIVE heard quite clearly,also some telephony from the 4,000ohms, POST FREE. Itague(P C G G) provedinteresting;tothose un- ALL WIRELESS PARTS &SETS. Trade supplied. familiar with thatstation. Whether you buy a complete CRYSTAL DETECTORS, 2/6. Hackney and District Radio Society. Illustrated Catalogue A, including list of Stations Hon. Sec.-E.R.WALKER, 48, Dagmar Road, E.9. receiving set or design it your- 6d. post free. AT theweekly meetingoftheabovesociety on EONS WIRELESS SUPPLY CO., Dec. 14 a very interesting discussion took place on self, this book at 2/6 will save 115, FleetStreet,E.C.4. radiosubjectsingeneral.The ;secretaryinvited questions, and replied toall and sundry in a most you time, trouble and money. satisfactory manner. SCIENTIFIC APPLIANCES foppZliecar2,41'i")i. Wag GET IT TO -NIGHT AS YOU GO HOME LESSPARTS and Material,- at Lowest Prices. Ca.l and see our immetue stock or write for Information and l'rices. Inn Centre cy London, Top of Xongsway. ANNOUNCEMENTS Obtainable from all newsagents and book- SCIENTIFICAPPLIANCES, " AmateurWireless andElectrlcs." Edited by stalls, or send us P.O. for 2/8 and your copy 11 and 29, Sicilian Avenue, London, W.C.1. Bernard E. Jones.Price Threepence.Published on will reach you in two days. Thursdays and bearing the date of Saturday imme- diately following.It will be sent post free to any partofthe world -3 months,4s.&I.'6 months. 11Zabio Prers D"egT:Idg', 6s.9d; 12 months,r7s.6d. Postal Orders, Post LONDON, 1V C Office Orders, or Cheques should be made payable PICK UP to the Proprietors, Cassell & Co. Lta. General Correspondence is to be brief and written on one side of the paper only.AU sketches and AMERICA drawings tobeon separate sheets. Contributions are always welcome, will bepromptly if you can on your considered, and if used will be paid for. PORTLAND'S PARTS BY POST IND -AERIAL outdooraerial,but Communications should be addressed, according to HOOK hook up an indoor theirnature,toTheEditor, The Advertisement 91 .-2,erial on Manager or The Publisher, "Amateur Wirelesstt La Belle Sauvage, London.E.C.4. "EBONITE s.d. £ s.d. S x 7 12 X 10 ... 6 IND-AERIAL HOOKS 4 X 4 ..... 1 3 ' 17('X 81... 6 and let the family get the broadcasting.Ind -Aerial 17 X 51 1 ril x8i...... 12 10 Hooka go on the picture -rail and support aerial ope so x6 ...13 0foot from tFe wall.Results willcharm you! 7 X 5 ...13 0 P.O. for 10'6 brin7s four, post free. QUARTER, MAT.RRITigif IND-AERIAL CO. (Dept. Al) 47, VICTORIA STREET, S.W.1 Postage Free-Any Sine Cut JAMES PORTLAND, 39, SINCLAIR ROAD, OLYMPIA, W.14 ELECTRADIX RADIOS. Querist's Coupon Available until -- Mr. Portland Stocks 200 Wireless Parts 1.11.111~1.11111011111111/11111111110111r10~~~0 IMMEDIATE DELIVERY Saturday, Jan. 6, 1923 FROM OUR HUGE STOCKS Everything from a Recorder to Hello! 15J- KING'S FOR VALUE Hullo !15/ - an Earth Clip. IN 20 MINUTES can be assembled IN 20 MINUTES. ASK The best equipped City depot. COMEAND SEE US ALL.BRITISH MANUFACTURE. Can he used with Broadcast Licence. FullSet of Parte for Broadcast Recepton, wave -length 300-800 metres. " A. W. 9, COLONIAL AVENUE is King's No.9. Parts consist of Mahogany Buse and Ends, 9 x 3} Inductance Mounted. firstopeningonleftin the '.:1,)NtalDetector, Blocking Condenser, Terminals,Ivorine Tablets,Slider Rod and forList of Minories,nr.Aldgate Station, Plunger.Assembled and tested, 4'- extra. Metropolitan Railway. One Pair of Headphones Given Away FREE with Technical every 20thorder received. Cash with Order. post LESLIE DIXON & CO.,Are 116. Stamp for List. Books. 9,COLONIAL AVENUE, MINORIES, E.I. HAMMOND & KING. 51, Berwick St.. W.I.Veit Gel/rid 6753 BEGINNER'S GUIDE TO WIRELESS Fxplains inplain, everyday language, everything THAT BOOK YOU WANT beginners wish to know about Wireless Telegraphy. ON WIRELESS OR ANY OTHER TECHNICAL SUBJECT HOW TO ERECT, CONNECT, AND MAKE all the apparatui required for reception of telephony or morse, Foyles have it or will quickly obtain it. and full instructions and diagrams ler making coils, tuners, and 1,000,000 Vols. (Second-hand and New) on Techni- comthete valve and crystal sets.112 pages, price 1/- post free. cal and every other conceivable subjectinstock. Teaks sent o,, eWroval.11.7 Tie Joe Catalogue ret ()ice) mention n: SAXON RADIO CO. (v'), South Shore, BLACKPOOL rtgreirtnreuts.Bents- Purchased. 32 page Catalogue of Wireless Apparatus. 3d. post free. FOYLES, 121, Charing Cross Rd.. London. DECEMBER 30, 1922 715 ernateur Wireless Wireless Supplies Instrument Order at Once if you require Prompt Delivery QEvertested y on an Aerial before despatch and asignedCertificate Q61 Headphones attached to each. 4,000 21./ per ohms " pair Every Set Guaranteed. Beautifully finished, highly sensitive, detachable receivers. IMMEDIATE DELIVERY Illustrated Wireless Catalogue now ready, post free, 3d. THE JEARY ELECTRICAL CO., LTD., 8, LAMBETH HILL, and 97, QUEEN VICTORIA ST., LONDON, E.C.4. And at Glasgow, Birmingham, etc.

FEL ..OPHONE 12 -Valve RECEIVER for plug in coilsin Oak Cabinet,Headphones, Batteries, Accumulator, Aerial and Insulators (Including Tax)£ 12 FELLOPHONE 2 -Valve AMPLIFIER in Oak Cabinet (for Loud Speaker), Including Tax Z7 SUPERCRYST, CompletewithAerial, Insulators and Headphones, In - chiding Tax...£4 7 6 HEADPHONES, 4,000 ohms 1 1 LOUDSPEAKERS, MULLAR D and COSSOR VALVES. GRID LEAKS. Variable and Block Condensers, Telephone Transformers, £1 DEMONSTRATIONS. 9 a.m. to 5.30 p.m.8 to 9 30 p.in. SATURDAYS. 9 to s p.m.8 to 9.30 p m. SUNDAYS by appointment.

F. N. GOUVY & CO., Ltd., 31, Upper Brook Mews, Lancaster Gate, near Paddington Station.

DO YOU READ PRACTICAL BOOKS ?

See Cassell's ListofTechnical,Practical and Money -saving Reqiskred N? 1045 D Passed IN PAG I: B.:oks.A p.c. will ensure your receiving it.

D3ABy Ea -7; CASSELL & Co., La Belle Sauvage, LONDON, E.C.4. AMMAR flllltllllIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIUIIIIIIIIIIIIIUIIIilIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIItts es it=1"We reply by return"It= HERE'S just the Set you want to enable you 1T" to enjoy the splendid Concerts now being u Apparatus at YOUR Price being broadcast from fourcentres. An excellentInstrument, moderately priced-and so 11 The following are a few items from our lists, and should interest simple to operate.One knob controls the whole Es you.Every article carries our money -back guarantee with it. LI or the tuning ;there are no irritating adjustments FilamentResistancePanel Brass Rod, square, I in. x I in., u Mounting 2/6 per foot... 6d. to make.Further Valves can be added at any Crystal Detector single cup ...2/9 Brass Rod, round, I in., per ft.6d. time, so that at any future date you can add a Loud s Ditto double cup ...3/6 Ditto, in., per foot ...5d. n

Crystals, all kinds, per pkt....6d. Ditto,u in., per foot ... 1-1 Speaker and enable everyone in the room to hear Wood's Metal, per stick ...Set. Strip Brass, b in. x I in., per ft.6d. Buzzers for testing Crystals ...216 Aerial Wire,7/22 Stranded in comfort.In addition, by the aid of a special es Inductance Sliders to fit u -in. Copper, per ico ft. ...4'6 Loading Panel, to be attached to terminals A and 9d. Insulators, egg pattern, each 3d. Voltmeter, o-6 volts ...... 6/6 0 E, its present wave -lengthlimits can be increased to include the Paris, Hague and Berlin Concerts. Pos'age extra on all above. Send to -day for your copy of our Free List,- e ELECTRICAL SUPPLY STORES, Size 7 in. by 5 in., mounted on Es polished mahogany Cabinet, com- .D 5, Albert Terrace, King Cross, Halifax, Eng. plete as illustration but without Valve. Catalogueof'phones, 113L__-_ -J I ICI Jot IC) loud speakers, batteries and other components sent post free. - - G. If for use with Broadcast GENTS' Licence each instrument must be stamped B. B. C .at an MAKE FITMENTS extracost of 32/6.

II11111111111111111111111110 iiiiiiiiii 11111 1111111111111111111111

Send for our sundries pamphlet, The PETO SCOTT Co., make use of our stocks, ask us Radio Headquarters, toquoteforyourwholesale requirements 64, HIGH HOLBORN, W.C.I.

1.11111111.01111111111111111111111111111111111I1111111111111111H1111 GENT & CO., LTD., Faraday Works, LEICESTER

Transtormer London 25, Victoria St., S.W., Delivery Irom Stock Newcastle.on-Tyne: "Tangent House," Blacken Street 'MARSHALL ALL Wirdess 716 DECEMBER 30, :022 Otnateur It's the results that count.

IN choosing your Broadcast Receiv- ing Set or Head 'Phones do not be tempted by cheapapparatus.You would probably get results, but of a Get the No. 81233 crude and uncertain nature. STERL NG full measure of enjoyment by using HEAD 'PHONES apparatus Which can be relied upon. 775/1,

6T-42;1 1.'s Before deciding on your purchase writefor our literature or call at our showroom for freeadvice.

11.

To be obtained from all dealers or direct from_ STERLING No.1 CRYSTAL RECEIVING SET. Ltd., Complete with one pair Cl 1h,nbie Head Telepicnic.,, Will Sterling Telephone and Electric Co., specialcoilforParis Time Signals. Rangel calks. 210/212, Tottenham Court Rd., London, W.1. Tch'chola No. 4141 .31 use= (; lines).Telegrams :Cuc.tms, all Broadcast Radio Appar- Works :DAGENHAM, ESSEX. We Guarantee thatsoldatusus conforms with the BRANCHES NEWCASTLE -ON -TYNE: 9. Clavering Place. conditions of the Broadcaster'sb3I Licenceissued by the CARDIFF:8, Park Place. Postmaster -General. MANCHESTER:14, St. Peter's Scp.lare.

BROADCASTING HeadphonesSplendid Crystal HAS NOW BEGUN! Detector Have you obtained your Set yet ? Mounted on Ebonite. t}.....40 Our No. 1 CRYSTAL RECEIVING SET is suitableforreception of all broadcast matter fora 219 range of 20-30 miles. TYPE APPROVED BY P.M.G.Rcg. No. 126. Price 35s. Plus 7s. 6d. broadcasting commission. 'PHONES.British made, wound to 4,000 ohms. Price 25s. AERIAL EQUIPMENT, comprising 100 ft. 7/22 Beaver Complete S.W.G. Stranded Aet ial Wire and Insulators. 4/- extra. COMPLETE EQUIPMENT, ready to "Listen - 4,000 ohms total Crystal Sets Resistance. NO. 1 unassembled 15/ - in."Price £3 3 0 Plus 7/6 broadcasting commission. Double Headband. No. 2 unassembled...20/-, Guaranteed highly efficient. No. 3 assembled, ready " Excellent Results." "Costs Nothing." Complete with Cords.Ball for use 24/ - West Kensington,Nov., andsocketjoints; highly Complete with Splendid Tested " to know that in spite of the fact thet I base a-valve polished nickel cases ;best and Guaranteed 4,000 ohm :set,I prefer 1i:telling-in en the Broadcastinz Co.'s Transmission r)f your No. I Crystal receiver, which gives e..vcciLet.i'suils, and unlike Valves Tungsten steel. magnets. Phones .. 45/-4 costs no! .1iinA>: -ALL GOODS SENT POST FREE

Write for Illustrated Catalogue of all Radio Accessories BEAVER ELECTRICAL SUPPLY CO. 109,REGENT STREET,LONDON,W.1 BOWER ELECTRICLTD., Telephone flEILRARD 1900 : 15,GRAPE STREET : Special Terms to Trade. All Cheques and Postal SHAFTESBURY AVENUE.London,W,C.2 BEAERSeders to be crowd London Jotnt City and midland Bank

Yrinted and Published in England by Cassatt & CorapaNY, LIMITED,Ludgate Hill. London, E.C.4.Sole Agents for South Africa. CENTRAL t'uws AGENCY, LIMITED, Saturday, December 1922

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