incorporating wireless weekl

WIRELESS. incorporating " Wireless Weekly," AUGUST 71926.,

INCORPORATING

WIRELESS WEEKL

MOL

By PERCY W. HARRIS, M.I

A NEW TYPEBy J. H. R

B.Sc. (lions.), A.C.G.I.,

" Cartoonigrafs " Corn

Il WIRtLESS. Au gust 7, 1926.

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August 7, 1926. WIRELESS. 361

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THE WIRELESS CONSTRUCTOR has by far thelargest net sale of any technical or semi -technicalwireless journal; whether monthly or weekly. During1925/1926 the advertisement revenue per issue wasby far the largest of any wireless journal and reached

WIRELESS (incorporating Wireless Weekly) has thelargest certified net sale of any weekly wireless paper(auditor's certificate for 115,536 copies per week justissued). During 1925/1926 the advertisement revenueachieved the magnificent figure of LI,000 per week.

MODERN WIRELESS comes next to our journalTHE WIRELESS CONSTRUCTOR in the monthlyfield and has a net sale far in excess of any monthlyoutside the " Big Four " of the Radio Press Limited.During 1925/1926 the advertisement revenue per issuewas higher than any other wireless paper (except ourown Wireless Constructor) and reached £3,067.

THE WIRELESS DEALER going directly to over5,000 individual members of the trade has carried duringthe last year a very large volume of advertising. Togive you same idea of this it is sufficient to say that" The Dealer " has carried 56 per cent, more advertisingper issue than any weekly wireless trade paper.

From the above facts it is clear that Radio Press papersare pre-eminent in the monthly, weekly and trade fields.

RADIO PRESS LTD., BUSH HOUSE, STRAND, LONDON, W.C.2

Augpst 7. WIRELESS.' 363

rI

S

41 TIMM .

INCORPORATING

WIRELESS WEEKLYVOINT EDITORS

PERCY W. HARRISJ. H . REYNER

B.Sc.(Hons.), A.C.G.I., D. I .0 . , A. M. I. E .E.ASSISTANT EDITOR

G.P. KENDALLB. Sc.

TECHN/CAL ' D/RECTOR

JOHN SCOTT-TAGGARTF. Inst. P E.E.

THIS WEEK'S NOTES AND NEWSLabour Saving

SAY, bo's and bo'esses, guess I'mjest tickled to death! Here's

Tom Blevins, a Utah cowboy, who callsthe cows home with a portable wirelessset and loud -speaker instead of sing-ing to them! He receives it fromstation WGES, and wrote to thestation telling them that " they surewere saving his voice." If his loud-speaker is anything like theone owned by that neighbourof mine, of whom you hear somuch, I shouldn't be surprisedif it causes a stampede one ofthese days.

Local InterferenceAFRIEND of mine has

recently compiled a listof all the sources of interfer-ence with which he has comein contact. It certainly is aformidable affair, and showshow careful one' would haveto be in choosing a situationwhich would be free of all" local " interference, with-out even considering such bug-bears as spark stations andatmospherics. Chief of thenuisances on this list areflashing signs, X-ray machines,vibro - massage machines,tramways, motor commuta-tors, and even the ordinarycar magneto.

International Programmes

"rJNCLE ARTHUR," though not

in Great Britain very often,is, you may be sure, remembering theold folks at home. He is now, I hear,forming a " Commission for Intellec-tual, Artistic and Social Advance-ment," which will promote the schemefor international programmes which isto start in the autumn. Under thisscheme there will probably be an" English night," when the B.B.C.would relay English programmes, as

sent out from other countries, and,perhaps, a French night, when all theEuropean countries except Francewould broadcast special French pro-grammes, which would be picked upand relayed by the French stations.This seems to me an extraordinarilyinteresting scheme, and I am surethose with " DX " sets will lookforward to its commencement.

Portable Sets !THE Radio Club de France is

equipping various refuges formountaineers with wireless apparatus,both for" transmission and reception,in view of the difficulty of fitting themup with the telephone. Speciallyrugged apparatus is to be used, andthe difficulties of getting it up intoposition are pretty serious, as most of

these refuges are higher thanany animals can reach; the

Preparation:. for the National Radio Exhibitionat Olympia from September 4 to 18 arealready well -advanced. A preliminary list ofexhibitors and staid numbers will be given in our

nestSpanish Airways

SPAIN is pushing ahead with theradio equipment of her aircraft,

and I now hear that twenty-three Mar-coni " AD6 " type sets (the type usedso extensively on British 'planes) havebeen installed. Further large ordersare on hand at present. The groundstations,. about ten in number, arevery .similar to our own " Cr-r-roy-don " that we knew so well before thedays of broadcasting, but who is now,I am afraid, somewhat neglected.

entire apparatus will have tobe carried up on men's backs I

The Swedish " Big Noise"SINCE I wrote about the

erection of a high-ppwerstation in Sweden on thellines -

of- Daventry, I have heard -

officially that it is to `` out-5XX 5XX," as 30 kilowattswill be used at first, and pos-sibly 50- kilowatts afterwards.It is to be at Motala, andshould be quite a " bignoise."

THE latest ships to beequipped with radio are

eight -whalers. The apparatuswill consist of standard Mar-coni telephony transmittersand receivers.

Strange !THERE is quite one orchestra in

the States that does, not playjazz ! Stranger still, there is a chancethat listeners in this country mayhear it. It is the New York Phil -Lharmonic orchestra, and it will broad-cast from WJZ, the Bound - Brookstation. If it is at all possible, theindomitable staff at lieston will bravethe fury of the X's and " put itthrough." The broadcasts will nottake place just yet, however.

(Continned on next page.)

364 WIRELESS. August 7, 1926:

We are hearing a good deal lately aboutthe use of wireless on trains in America.This view shows three engineers of theZenith Radio Corporation carrying outexperiments on a New York Central train

Perhaps !AHIGHLY ingenious theory which

is said to explain those freakreceptions -which occur so frequentlyhas just been put forward in all goodfaith by an unconscious humorist. Itis that the Heaviside layer is per-forated; and occasionally a wave goesstraight through, slides along the top,and' falls down again !

RevelationsISHOULD think, from the

advance news of the com-ing Radio Exhibition that Ihave received, that the" Attaché - case " receiverswhich will be on show in largenumbers will create quite asensation among those cynicalindividuals who. think thatwireless and weight always gohand - in - hand. Sets aresteadily becoming smaller, andresults (or, rather, the owners'accounts of results) larger.

A New ServiceTELEGRAMS will be sent

direct from Nauen, inGermany, to Rio de Janeiro,commencing early in August.The charges will, I hear, beconsiderably less than those at'present in force. Germanyis already working directwith North America, Argentina, Java,China and Japan.

Quite Untrue !APARTICULARLY bad burst of

interference to broadcast re-ceivers on the South Coast was re-cently traced to a passing liner, whichcould' be quite clearly seen from shore.A Morse reader was able to supplythe call -sign of the interfering station,and the owner thereof was looked upin the " book of words," the culprit

THIS WEEK'S NOTESAND NEWS

(Continued)

thus being found. The rumour thatcoast -dwellers read the Morse by thesparks on the ship's aerial is, however,quite incorrect.

Loud -Speakers AgainFROM all round news is coming to

hand of complaints about theraucous loud -speaker and the nuisanceit causes. Reading is the first placeto take the matter in hand seriously,however, and since the passing of anew by-law it is illegal to operate aloud -speaker in such a manner as tocause annoyance to. residents. Bravo,Reading! The loud -speaker hog canmake himself a real nuisance, and itis not necessary to use six or sevenvalves on the local station just in orderto show your neighbours what a won-derful set you have. Councillor R.Ellison, of Sidcup, has thought of ascheme for carrying the idea a littlefurther, and hopes to form the S.C.N.,or the " Society for Checking Noises " !

I do not advise you, however, tofollow the example of the 131ackfriarslady, who recently smashed up a setand aerial belonging to someone elsein the same house because, like Mac-

Daventry's " birthday " was celebratedon July 27: A somewhat unusualview of the station buildings appears

above.

Finnan, will play fairly frequentselections from the older dance reper-toire. The Savoy Havana Band is" coming back " on Thursday,August 5, and the Orpheans will betaking a fortnight's holiday fromAugust 15 onwards.

Coming EventsTHE first broadcast of Evensong

from Westminster Abbey, whichwas originally announced for July 22,

has had to be postponed for afew weeks. It is, however,nothing more than a postpone-ment.

This view shows the aerial being fitted to thetrain referred to in connection with another photo

on this page.beth, they, with the help of theinevitable loud -speaker, had " mur-dered sleep." She was fined ls. Isuspect the magistrate of beingsympathetic !

A Step FurtherTHE recent duel between Mr. Jack

Hylton and Sir Landon Ronaldhas encouraged the B.B.C. to carrythe " jazz -v. -music " controversy astage further. For the present, theLondon dance band, under Mr. Sidney

On August 16 " The WhiteChateau," which was broad-cast last Armistice Day, willbe repeated. August 16, youwill remember, is the anni-versary of the landing of theB.E.F. 'in France in 1914.

The Community Singing inthe churchyard of St. Martin -in -the -Fields is, as I pre-dicted, to be broadcast onThursdays from 1.0 to 1.20p.m. The usual gramophonetransmissions will therefore bepostponed till 1.20, and willcontinue till 2.20.

* * *

On August 12 Dover ishaving a " look -in." The Band ofthe 2nd Battalion of the Queen's OwnRoyal West Kent Regiment willbroadcast from Granville GardensPavilion on that date.

* * *

On August 6 the torchlight tattooat the Depot, Royal Marines, Deal,will also be broadcast. The DepotRoyal Voluntary Cadet Corps will alsotake part.

CALL -SIGN.

.


HE system of reactionpopularly known asthe Reinartz hasmany advantages, oneof the principal beingextreme smoothness ofoperation which can

be obtained with its aid. The present

Ci 0005

.001C. B.2

C 3 .0003

R6POTENTE?

A REINARTZTUNED -ANODE.0.. SET . . .

By W. Q. KAYThis screened -coil four -valve set uses a very simple stabi-lising scheme, and will be found very easy to operate.

contains a second tuned coil, this coil,however, being provided with an over-hanging portion, tapped at variouspoints. The anode of the previousvalve is connected to one of thesetappings, so that the energy is passedon from one valve to the next by thismeans.

R -FHOKE

R424fra.

R

uZ

L _

itself. This has been done accord.ingly.

L.F. CouplingFollowing this valve are two stages

of note magnification. The first ofthese is choke -coupled, a simple choke

+3

+2

cis

R5

2

1

3

J2

R 3 A

H.T.

Fig. 1.-The L.F. choke, fixed condenser, and resistance, marked Z, C5 and R5are all contained in one unit.

receiver is the result of an attemptto apply these principles to a tuned -anode circuit. In many cases to -day ahigh -frequency amplifying valve isdesirable and often essential in orderto obtain some special degree of selec-tivity. If, therefore, we could obtaina receiver in which the Reinartz con-nection, with its several advantages,could be employed on the high -fre-quency valve, the resulting combina-tion should be a very good one.

The CircuitThe circuit employed is shown in

Fig. 1. The aerial circuit, is of theusual type, the aerial circuit properbeing connected across a part of thegrid coil only iu order to improve theselectivity.

The grid circuit of the second valve

ReactionThe anode of the second valve is also

connected to the tapping points on thecoil, through a variablecondenser, in order to pro-vide the necessary re-action effects. The secondvalve is arranged to actas a detector, for whichpurpose the usual con-denser and leak is incor-porated in the grid lead.

As the bottom end ofthe coil is connected tothe high-tension terminal,in order to provide theH.T. voltage for the pre-vious valve, it is neces-sary to connect the gridleaf: to the filament andnot across the condenser

mmo

respectively in this circuit diagram,

unit being incorporated for the pur-pose.

(Continued on next page.)

The metal screen seen behind the third valvefrom the left is connected to earth.

366 WIRELESS. August 7, 1926,

A Reinartz Tuned -Anode Set-continuedIn order to prevent the high -fre-

quency currents from passing throughthe low -frequency paths in the circuit,a high -frequency choke has been incor-porated in series with the L.F. choke.This also serves to improve the reac-tion effect which depends on the H.F.currents flowing through the circuitcomposed of the condenser C, and thecoil L,.

The second stage is a straightfor-ward transformer -coupled stage. Forthis purpose a medium -ratio trans-

former is required, assuming that anordinary L.F. or small -power valve hasbeen employed in the first stage.

I myself have used a B.T.H. instru-ment in this case having a ratio of4 to 1, which gives excellent quality.

SwitchingJack switching has been incor-

porated in order that three or fourvalves may be employed at will. Thelast jack is also a filament switching

one, being so arranged that it cuts outthe last valve when only three valvesare being used. The filament controlsaro the new Lissen " variable " fixedresistors. These are simply the well-known Lissen rheostats without theknob and dial.

They can thus be fixed on the base-board, set to the correct position andthen left. A simple on -off switch dis-connects the L.T. battery when the setis not in use.

A point of particular interest is that

72 -1 + + +3 +2 +1 A LiTAP?

Fig. 2.-The disposition of the coils upon the baseboard should be carefully copied from this wiring diagram.

August 7, 19-26. WIRELESS. 367

A Four -Valve Receiver of Special Meritpotentiometer control is used on thefirst H.F. valve, in place of one of themore usual neutralising methods.

A Screened CoilThe second coil has been

-enclosed in one of the screenedcontainers developed by Mr.J. H. Reysier, so that all mag-netic interaction between thefirst and second circuits iseliminated. In such circum-stances the only tendency tooscillation is that due to theinternal capacity of the valveitself, which, though present, isfairly easily controlled.

Potentiometer control has'

tice, the results obtained being up tothe standard usually obtained with aneutralised H.F. stage. This is pro -

.0003 (reaction) condenser being onthe sight.

The potentiometer and on -off switch

therefore been incorporated, thetheory being that the amount of damp-ing required to maintain the circuit in

OI

*3 *2 06

@5

Fig. 3.- The connections between thesockets of the screen and the terminalsthereon, and also the numbers of thepins on the coil itself may be gathered

from this drawing.a stable condition would be very small,and would not affect the selectivity ofthe circuit to any appreciable extent.This proved to be the cue in prac-

The panel lay -out is a simple one.bably due to the fact that the firstcircuit is already damped by the -aerialcircuit, so that the alight additionaldamping produced by the potentio-meter control is not serious. Thisargument would not hold for morethan one stage of H.F., and only holdsin this case because of the use of ashielded coil.

ComponentsThe following components will be

required. For convenience the manu-facturers' names are given after eachcomponent.

One panel, 1S in. x 7 in. x / in.(Trolite).

One cabinet to suit, with baseboard10 in. deep.

Two .0005 variable condensers, slow-motion. type (Jackson Bros.).

One .0003 variable condenser, slow-motion type (Jackson Bros.).

One coil screen (Peto-Scott Co.,Ltd.).

One Reinartz coil or, alternatively,one coil blank (Peto-Scott).

One L.F. choke unit complete(Bretwood).

One H.F. choke (Lissen).One L.F. transformer, 4 to '1

(13.T.H.).Four valveholders (Lotus).Three baseboard -mounting resistors

to suit valves (Lissen).One on -off switch (Igranic).One potentiometer (Lissen).One single -coil mount (Burne-Jones

&-Co.).One double circuit jack, No. 233

(Bowyer -Lowe Co.).One single circuit jack, filament

switching type, No. 234 (Bowyer -Lowe Co.).

One clip for grid -bias battery (A. F.Bulgin & Co.).

One .0003 fixed condenser with seriesclip and 2 meg. leak (Dubilier).

One .001 fixed condenser (Dubilier).Mounting the Components

The construction of the receiverrequires a little care owing to the com-pact layout adopted. The -panel com-ponents occasion no difficulty. Thethree condensers are first mounted, the

1 components is not critical, pro-

are then mounted in the posi-tions shown, while the two jacks'are mounted. in the right-handtop corner, as will be seen fromthe panel diagram and photo-graph a accompanying thisarticle. The panel may now beput on one side, and the re-mainder of the components laidout on the baseboard.

The single -coil mount is placeden the extreme left of the base-board, and the screened coil nextto it. The position of these two

vided that the plug-in coil ismore than 11 in. away from thecopper screen.

The H.F. and L.P. chokes and theL.F. transformer may then be laidout, and finally the three fixed re-

WIRING INSTRUCTIONSJoin terminal A to a spade tag (flex lead).Join G of VI to one side of LI and thence to

fixed vanes of Cl.Join terminal E to other side of Ll and thence

to other side of Cl. Terminal E also to one sideof C6 and thence to slider of Rfrand to terminalE of screened coil.

Join remaining side of C6 to one side of R6 andto black wander (flex lead).

Join A of V1 to fixed vanes of C3 and to spadetag (flex lead).

Join other side of C3 to one side of R.F. chokeand thence to A of V2.

Join other side of R.F. choke to terminal Pof amplifier unit.

Join H.T.+ of amplifier unit to H.T.+2.Join terminal 1 of screened coil to one side of

C4 and to fixed vanes of C2.Join other side of C4 to G of V2.Join terminal 2 of screened coil to other side

of C2 and to H.T. +1.Join G of amplifier unit to G of V3.Join L.T.- of amplifier unit to G.B.-1.Join A of V3 to contact 4 of (bottom contact).Join contact 1 of J1 to contact 4 of J2 and to

H.T.+3.Join contact 2 of JI. to I.P. of Ti T2.Join contact 3 of J1 to O.P. of Ti T2.Join O.S. of Ti T2 to G of V4.Join I.S. of Ti T2 to G.B.-2.Join A of V4 to contact 3 of J2.Join one side of 113 to one side of R2 and thence

to L.T.+, H.T.-, one side of R1, remaining sideof R6, and the free side of R4 respectively.

Join other side of R1 to one filament contactof VI and V2 respectively.

Join other side of R2 to one filament contact ofV3.

Join other side of 11.3 to contact 1 of J2.Join contact 2 of J2 to one filament contact

of V4.

Join G.B.+ to L.T.- and thence to one sideof S.

Join other side of S to remaining filamentcontacts of V4, V3, V2 and Vi respectively.Join latter point to red wander plug (flex lead).

sistors and the four valve holders maybe placed in position.

(Continued on page 395.)


A recent portrait of Sir Harry.

IT'S a serious task, ye ken, thisbein' unco' funny by wireless

It's so different from the ordinarybeing funny on the stage that itseems like a new art, which we poorcomedians have to learn right fromthe beginning, like we learnt to befunny in theatres years ago. Butthere's always something new to learnevery time ye broadcast and everytime ye listen -in to anyone else.

That Deathly SilenceThe difficulties ye meet are all so

new and unexpected. I think per-haps it's the absence of applause isthe worst obstacle. And the moreapplause ye're used to on the stagethe worse it seems hearing thatdeathly silence in the studio. Here'sa description of the first time I everbroadcast.

I was fair nervous to begin with,I can tell ye! I was thinkin' all thetime of haw I was tae get all my voiceinto the microphone without any ofit escapin', and wonderin' how onearth I was to get on without beingable to depend for a laugh or twa onnia little twirly stick or wee dances.Eventually I decided to dress com-pletely as if I were on the stage,carry out every action and gesturejust as exactly, and, in short, behavejust as if I were actually facing anaudience of millions instead of merelytalking to them. It was weirdenough, however, and after ma firstsong I got real microphone -fright.

The Instinctive PauseTell ye, it was like this. I paused

instinctively to hear the gale oflaughter and clapping. But there'was never a whisper The pauseseemed ages long, and then ma heartbegan tae sink, even though I knewthe jokes were as guid as ever. Yetthis is not enough to satisfy any

*aLo

BEING FUNNY BY WIRELESSb id4)

16 By SIR HARRY LAUDER'II)

r_&.L,EPOliiDcg4IPLVOLWPc4-1c43[D15,cf,rigLiDdi:1[54-ch5,0[ff3c..t,L5,0..foLn-Vt_Pcn5c§,,t§:,OLTL§:di-'ig,liThilil

A special article for "Wireless" readers which gives an interesting insight g,

into the difficulties "at the microphone end."

comedian. There is a strange thingabout audiences which can never beestimated beforehand, and that istheir reception of wee true stories.There's some crowds will laugh up-roariously at things which others passin silence.

Strenuous!How, therefore, is the unfortunate

radio -comedian to judge which willamuse the universal listener -in? Mostof us decide it's little use trying, and

Lady Lauder is here seen listening toone of Sir Harry's broadcast per-

formances.

act on this principle. Just thoseitems which get most applause of allon " the boards " are selected, andwe hope our very best that somethingin the programme will please every-body. Still, it's a scaring thing, thisperforming before an unresponsiveaudience, for, ye see, in any otherplace, lack of response tells ye there'ssomething seriously wrong with yourwork. Oh, it makes ye wipe ye brow,does this broadcasting!

Little Orchestral HelpOne thing we funny men always

have to remember in sending our funacross the ether. Absolutely the wholeeffect of our work depends upon whatwe say and the way we say it.Although the orchestra is helpful, stillit is naturally impossible to dependupon it to cover any awkwardmoment-as it will on the stage-be-cause the conductor can judge no morethan yourself just when a wee jokehas failed to " get across," and conse-quently misses the psychologicalmoment to strike up. So what wehave to do is this. A sequence has to

be invented, with great- care andaccuracy, which will lead the listeneri-in into the best poz.sible frame of mindto appreciate the jokes. Gradually,ye ken, their minds get " in tune,"and they begin to laugh easily. Thenone or two of the best of the jokes, o.song, and they're all telling oneanother how fine that little turn was I

The Greatest DifficultyOur greatest difficulty at present is

that it is naturally impossible to hearoneself broadcast. Listening -in toanother comedian is not the same thingat all, for you must know thatevery comedian depends for his ap-peal on entirely different factors.However, as it seems impossible 'thatan invention could be made to let apuir comedian-laddie listen to his ainjokes (an' perhaps it's as weel !), wemust just gang on and be satisfied withthe reports of our frien's-and ourcritics.

A Great OpportunityStill, despite all the worry of it, it's

a grand opportunity wireless has givenHS who can be funny. A new vista hasopened to us. Where before we were

The famous comedian before the micro-phone on the occasion of his broadcast

from the Ideal Home Exhibition.

only able to appeal to the limited num-ber of people who can come to theatresand music -halls, now there is the whole

(Continued on, page 396.)


An account of one of the few

HE rather severe stormwhich took place invarious parts of the

'a> con n t r y recentlyhas again raised theold question of " thelightning danger."

From the point of view of interest,the writer, though associated withwireless since his school -days, in mostcountries of . the world, has only ex-perienced one occasion when it couldbe stated definitely that an aerial wasactually struck by lightning.

Other CasesThere have, of course,

been several other instancesoutside my own experience,as, for instance, the descrip-tion of events at the ElstreeLaboratories on April 7,given in Vol. III, No. 10,but from personal contact thefollowing is the only occasionupon which any inconveni-ence was felt from the directeffects of lightning. .

Where It HappenedThe incident in question

took place in Hongkong, andas readers know this islandis not far removed from thetropics. Owing to this factthere are at times mostsevere storms eiperienced inand around that part of theworld, and though hardlycomparable with the moregenerally less severe storms of Europe,the occasion is, nevertheless, one ofinterest at this time of the year. '

A High AerialThe aerial, which was suspended

between two 220 -ft. masts, belonged toa- naval station, the installation beingthe usual transmitters of both sparkand C.W. apparatus, with crystal andvalve receiver.

During one evening, and withoutany warning, such as, for instance, theprevalence of atmospherics, a stormsuddenly " got up," the -^ry first flashof lightning striking the aerial.

The FlashAt the time the operator on watch

rec3rded instances of the striking by lightning of a commercial station.

had momentarily removed the 'phonesin order to exchange a few remarkswith a companion, when suddenly theflash came, accompanied by a deafen-ing report.

The building, which had previouslybeen illuminated by electric light,became totally dark so far as " man-made light " was concerned, but ap-peared to be quite appreciably lit upby a strong purple glow in the form of,tiny sparks creeping all over the wallsand windows.

The Earth SwitchThough there were, of course, special

switching devices on the station, where-by the aerial could be earthed, therewas not an opportunity of takingadvantage of this safety switch, onaccount of the suddenness with whichthe storm " got up."

It is not usual to experience stormsin this country of such severity as thosemet with in the tropics, but notwith-standing this fact, I am a very strong

advocate of that well-knownrule, " earth your aerial "and be on the safe side, andas confirmation of the wis-dom of this conclusion thephotographs we have seen,showing the damaged re-ceiver of an unfortunatelistener, are more thansufficient.

Where a flash of lightning might do real damage:part of the complicated system of aerials at the

Central Post Office, New York.

The Main DamageUpon the cessation of the storm,

careful examination of the station re-vealed the damage done to be mainlyconfined to the transmitting plant,though the accumulator battery, whichformed part of this component, escapeduninjured.

Perhaps one of the most remarkablethings is the fact that the receiverswere not injured, so far as results wereconcerned, the only evidence of roughusage appearing on the outside.

The aerial itself was destroyed com-pletely, various pieces of insulatorsbeing scattered about on the groundimmediately below; the masts, how-ever, were not damaged in any way.

i AN APPRECIATION

SIR,-I have constructed theWIRELESs transformer -coupledamplifier described by Mr.Stanley G. Rattee in thespecial amplifier number ofWIRELESS, and feel bound tothank him for describing sucha splendid little unit. Theamplification that can be ob-tained from it without anytrace of distortion is really re-markable, and for stability itis the most satisfactory ampli-

fier I have ever handled. I have beenexperimenting with power amplification,using 300 volts on the plate of the lastvalve (which then requires about 24 voltsgrid -bias), and find that the transformerand other components used by Mr.Rattee stand the strain imposed uponthem perfectly.

All thanks to WIRELESS and Mr.Rattee.-Yours truly,

ERNEST J. STIERRATT.Lowestoft.

NEXT WEEKPORTABLE SETS ON

THE RIVER

370 WIRELESS. August 7, 1926.

YOUR SET ANDITS EARTH

By Captain H. J. ROUND, M.C.,

Strange behaviour on the part of many sets, particularly neutralised ones, often means that the earth connection is nctdying its duty correctly. Captain Round explains just how the troubles are produced and gives the practical remedies.

N a recent article I dis-cussed some of thequestions involved int h e efficiency ofaerials, but I entirelyneglected certain verypractical cases where

aerials can be obtained, but earths are

Fig. 1. -If an aerial is connected toearth as in this diagram, the point E

is at zero potential.

difficult to get, and as these cases arefrequent, and cause trouble withvarious pieces of apparatus, they areof considerable importance. I shall, ofcourse, not be able actually to dealpractically with every case, becausethere are so many, but in the followingnotes will be found the general prin-ciple to follow in almost every case.

An Important SpotIf an aerial is connected to earth as

in Fig. 1, the point E is at zero poten-tial, and in design we try and get allour batteries, etc., connected to thispoint, so that whatever we do to themthere is no effect on signals, but if inthe earth lead we put a condenser C

Fig. 2.-The condenser C in the earthlead will bring about a distinct differ-ence of potential between the point X

and earth.

(Fig. 2), then there is a distinct differ-ence of potential between the point Xand the earth, and if our batteries areconnected to X (unless C is a verylarge condenser), we shall have our

batteries, telephones and our body con-nected to what should be a sacredpoint, and as a consequence-asidefrom variation of tuning as we moveabout with 'phones on our head-weshall get losses.

The same thing occurs in Fig. 3,where L, is the loading coil and L, is along earth lead, X again becomes asacred point. The case of Fig. 2occurs where we are using a capacityearth and that of Fig. 3 when using along earth wire or pipes from the topof a building. The remedy is the samein both cases, and that is to tune theearth connection.

Tuning the Earth LeadFig. 4 represents Fig. 2 modified by

the addition of a coil 1,2. If L, andthe earth capacity are in tune with thewave being received as well as theaerial and L then X is at earthpotential and no longer a sacred point.

Fig. 3. -In this case L1 is the loadingcoil, while L2 represents a long earth

lead.---Fig. 5 is Fig. 3 modified by adding

the condenser C to tune the earth,where, if C and L, are in tune withthe wave being received as well as L,and the aerial, then X is again atzero potential.

Practical MethodsAnd now my difficulty is to give you

ways of doing these operations cor-rectly. As a number of other ques-tionrare involved, I will take a simplesymmetrical case and discuss it indetail, and then build up more diffi-cult cases froth that one. Suppose youhave a small fiat and wish to erect anaerial and you have no satisfactoryearth, you want to do two things :-

(1) Get the maximum effectiveheight.

(2) Get the lowest loss aerial andearth system.

Choose your longest room, and acrossthe longest side, 1 ft. from the ceiling

Fig. 4.-If L2 and the earth capacityC is in tune with the wave being re-ceived as well as the aerial and L1,

then X is at earth potential.4 -4 -4.4 -4,41 -4 -4 -N -4 -4. -4 -4 -4 -4 -4 -*-4-4-4

and 1 ft. from the wall, stretch a wireover and insulate it at both ends.If you like to make the one wire intoa sausage, well and good; it will in-crease the capacity, but keep it awayfrom the wall and ceiling. Now acrossthe room underneath the aerial put asimilar arrangement 1 ft. from thefloor and 1 ft. from the wall.

The Zero PointThe aerial and earth capacities being

how roughly equal, your tuning coilshould be tapped in the middle for anybattery connections, etc., as that point

Fig. S.-This circuit is similar to fig. 3,but has the addition of the variable

condenser C to " tune" the earth.

will he at earth potential. A tuningcoil for such an arrangement shouldbe built generously, because it will haveto consist of a lot ofwire. Perhaps


August 7, :926. WIRELESS. 371

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Your Set and Its Earth-continuedtwo coils will be more convenient, and Isuggest they should be wooden frames,9 in. square, wound with No. 20enamelled wire spaced IT, in., if you donot mind the rather large appearance.The right lengths will have to be foundby experiment, but I suggest 200 ft. ofwire on each coil, say 70 turns.Tuning can be done by tapping on tothe coils. If the same number ofturns are used in both aerial and earthleads, then the centre point X (Fig. 6)will be your zero potential place, andyoir will have an aerial with nearly asgood tuning as a frame and with muchmore induced voltage.

The chief points to aim at hereare :-

(1) To keep bad dielectrics awayfrom both aerial and capacity earth.

(2) To get high efficiency in thetuning coils.

Any variation from these two pointswill result in weaker signals andworse tuning.

AlternativesHaving built up this symmetrical

arrangement, in which we have made

AERIAL

CAPACITY EARTH

Fig. 6.-By using the same number ofturns in this case in both aerial andearth leads, then the centre point X

will be at zero potential.

the reasonable assumption that aerialand earth capacities are equal, we canproceed to make variations. For in -Stance, if we have a real earth we canearth X and remove the lower partof the apparatus, and no change oflerial tuning will be necessary, or,eaving the lower part of the arrange -

Went alone below X, we can put anoutside aerial on (Fig. 7) and tuneit up, and we will know that X is areal zero point; or suppose we tuneup the whole arrangement to a sta-tion, then connect X to a gas pipeor radiator.

If variation of aerial tuning is re-quired, then a series condenser is re-quired in the earth lead because inthis case the earth lead is an induct-iice and not a capacity like the

capacity area (Fig. 8), and this seriescondenser should be adjusted until theaerial tuning is back at its originalvalue when used with the standardcapacity earth. Once this gas pipearrangement has been adjusted theaerial side can then be replaced by

an outside aerial, so that from thebasic system we have constructed aproper aerial system.

ApproximationI do not in all cases suggest this

roundabout way of constructing anaerial and earth system, but I give itas an illustration of the _Method of

TO OUTSIDE AERIAL

Fig. 7.- Having performed the opera-tions of fig. 6 an outside aerial can beattached and the point X again adjusted

to zero potential.

obtaining a correct system if it isrequired. Great accuracy in gettingX to zero potential is not absolutelynecessary in many cases-a little in-accuracy is allowable-in fact, it isvery difficult to know when X isexactly right. Slight variations fromzero potential of the point X are per-missible, but too much variationshould not be allowed.

In the case of Fig. 8, which I oftenuse for certain multi -valve receivers,I set the earth 'condenser. for aboutthe middle of the wavelength rangeI am using, and I estimate its valuethis way : I assume one microhenryper yard of earth wire, then I calcu-late the condenser in tune with thesemicrohenries at 400 metres and fix itpermanently.

With a NeutrodyneThe importance of tuning the earth

is mainly from the loss and stability

AERIAL

TO GASPIPEFig. 8.-If variation of aerial tuning isrequired, then a series condenser is

required in the earth lead.

point of view. One example of thenecessity of a good zero potentialearth connection is found in the neu-trodyne.

The neutralising in a neutrodynedepends upon the ability to pick outsome point on the circuit of opposite

potential to that inducing energyback through the valve, and it isobvious that we' must be very certainthat this point gives us the value ofopposite potential we desire at allwavelengths. But if the zero ofpotential is indefinite, shifting withwavelength as it will do if the earthis capacitative or inductive, the neu-trodyne balance will not be main-tained, and in that case a partialbalancing of the earth capacity orinductance is advisable.

My own 8 -valve neutralised,,receiver(the " Straight Eight ") is quite sen-sitive to a long earth connection, andin this case I balance the earth induc-tance out for a middle wavelength bythe rule I have previously mentioned.

Another TypeThe standard capacity earth I have

indicated is possibly larger than needbe if great care is used in construc-tion. For instance, a large spacedspiral 2 in. long and 10 in. diametercould be used; the rule for getting it'4,-4-4-1-64,4.-...-4.-4-4-4.-4-4----1---4-

Fig. 9. -- The earth inductance andcapacity can be replaced by a spiral,which if wound of too many turns willbe tunable by tapping the free end back

to some point on itself.

into commissioncommission being the same asbefore-that is, to tune up the stan-dard aerial and earth of Fig. 6,then to replace the earth induct-ance and capacity by the spiral,which, if wound of too many turnsto start with, will be tunable bytapping the free end back to somepoint on itself (Fig. 9), an arrange-ment which I saw a friend of mineusing in 1903 for receiving on 100metres.

In tjiese capacity earth arrange-ments, provided the point X has beenobtained properly, then it does notmatter to which side you connect thecrystal or valve grid.

I have indicated a crystal arrange-ment, the crystal being tapped offeither the earth or the aerial tuningcoil, and incidentally I may mentionsuch an aerial system is easy to neu-trodyne because we have a point ofopposite potential on the earth coilto play with, also the arrangementwould lend itself to single -valve recti-fier and oscillator arrangements forsuperheterodyne work.

August 7, 1926.

.44'4 +04

OPERATING THE "ALL -WAVE"

SINGLE -VALVE SETBy L. H. THOMAS

WIRELESS. 373

Ntstenimgoasa

Some helpful operating notes on the receiver which was described in detail in our last issue.

T does not always followthat the receivers thatare most easy to con-struct are most easilyoperated; unfortunately,the reverse is often thecase. In spite of this,

however, the reader who has con-structed the " All -Wave " single -valve set described last weekhas probably discovered forhimself by now that theoperation is every bit aseasy as the initial construc-tion of the set.

Detector H.T.There are, however, one or

two points which might havebeen overlooked, so that itwill .be as well to take specialnote of them. In the firstplace, if the valve used isone of the high -impedance,resistance - capacity type,which make very excellentdetectors, and are probably.the most suitable for use in asingle -valve set of this kind,the high-tension voltageshould nelser exceed about25 or 30 volts. If you listento the local station with thisvoltage, you will in allprobability find that the strengthof signals may be increased slightly by

E

For short wave operation a fixed con-denser may be inserted in series with Cl.

boosting up the H.T. voltage, but youwill soon find that it is worth while ifyou search round for " DX."

Author's ValueActually, with the original set, the

voltage used was 22k, and with thisthe reaction control was remarkablysmooth; it was also the easiest possiblething to tune in a station with the setwell away from the oscillation pointand then to bring it up to full

The finished receiver as seen from the back withcoils and valve in position.

strength by means of the reaction con-denser alone, without even touchingthe other control. If too much high-tension is used, however, this will befound to be a difficult, if not impos-sible, operation. Overlap -or " plop "sets in at once. The filament voltagealso could be kept as low as 4.5,although the rated figure of the valvein use is 5.5 volts.

Increasing SelectivityFor the reception of Daventry the

aerial should be attached to the anodeend of the coil La, by means of #theclip at the end of the length of flexfrom the aerial terminal. Thisarrangement will also work satisfac-torily right down to the ordinarybroadcast band of 300-500 metres, pro-vided that there is no serious interfer-ence from other stations. If there is,a useful increase in selectivity may begained by changing this connectionover to the end of L, and plugging asuitable size of coil in the socket. For

the 300-500 metre band a No. 1 or 14Dimic coil was used for La, and a No.35 in the aerial socket.

Should it be found that there is a" dead spot " in the band on whichreception is to be carried out, altera-tion of the size of the coil L,, or evensometimes a loosening of its couplingto La, will cure the trouble. The dead

spot is generally due to thefact that the aerial circuit isactually in resonance withthe secondary coil. Theamount of coupling betweenL, and La is, of course, afurther control of the Selec-t i ity--of the set.

' 'Ware DustIt is possible that after the

set has been in use for a longtime a slight scratching noisemay be -heard when the reac-tion condenser C, is rotated.This will generally be foundto be caused by an accumu-lation of dust on the plates,which have, of course, thefull potential of the high-tension battery across them.The remedy is obvious-cleanthem with a pipe -cleaner, or,eves better, wire a largefixed condenser in serieswith Ca.

Short WavesIf the reader finds tuning at all

difficult on the shorter wavelengthsan easy way of simplifying matters isalso to use a fixed condenser in serieswith C,, the tuning condenser. Oneof the " clip -in " type is most con-venient, as it may readily be takenout of circuit and the clips shortedwhen the set is used on the longerwaves. If one of .0005 is used, theeffective capacity of C, will be re-duced to .00025, and this, with theslow-motion control, should makeshort-wave work easy for the. mostinexperienced operator.

" MODERN WIRELESS "1 /- AUGUST ISSUE

NOW ON SALE 1/-

374 WIRELESS, August 7, 1926.

OCK><>0000000000000000.00<>00.00000000.0000000000000000000<x>

THE FUTURE OF BROADCASTINGBy Lt. -Comdr. the Hon. J. M. KENWORTHY, R.N., M.P.

On this page will be found the conclusion of Commander Kenworthy'sarticle, which appeared in our last issue, on the future of the Broad-

cast Service in Britain.

c0000000000000coocooccroe>c,000000caoco<>0000000A Warning

The history of the Road Fund buoysa shoal which we must take steps toavoid, or broadcasting will be runaground in the same way. The RoadFund is the proceeds of the motor -licences. When motor -taxation firstcame before Parliament for approvalit was solemnly promised that thewhole of the proceeds of the taxshould go to the upkeep and improve-ment of the roads. In this year offinancial stringency the Chancellor ofthe Exchequer has made abold raid upon the fund,and is coolly annexing1410,000,000 of money forgeneral revenue purposes.Unless very clear andadequate safeguards areinsisted upon by Parlia-ment we shall have a repe-tition of this sooner or laterwith regard to the broad-casting funds of the newBritish Broadcasting Cor-poration.Representation of

ListenersNext in importance, I

suggest that the views of thelisteners must be adequatelyrepresented before the Cor-poration. There shouldbe an Advisory Committeeappointed by listeners them-selves through their differentassociations and organisa-tions. This is a necessityin order that the views oflisteners should be keptbefore the Board of Man-agement of the new Cor-poration. There must bethe minimum of Govern -

of the greatest propagandist Govern-ment the world has ever seen. InRussia no licences are taken out, andprogrammes are provided free. Fromall accounts the programmes are good,particularly excellent music being pro-vided. But loud -speakers aboundeverywhere in the big cities, and evenin the large villages.

All the big cafes and every import-ant place, public squares, etc., haveloud -speakers. And from these loud-speakers are given out the news,

well for the Postmaster -General to talkabout continuity of programmes. Butwe are giving up the well -tried, and,on the whole, successful British Broad-casting Company for au entirely newmethod of managing and controllingwireless in Great Britain. Let ushope the experiment will be a success.

THE CENTRE PUNCH

The centre punch is absolutely anessential tool if exactness in markingout is required.

The punch is made of specially har-dened steel, and has a coned pointwhich is sharp enough to make a smallindentation in even hard steel, al-though it will not pierce or cut to anygreat depth. This small indentation issufficiently large to enable a drill toobtain a start in drilling a hole, andto keep the drill in the correct posi-tion during the first one or two revo-

lutions.

A PIONEER'S RETIREMENT

As we announced briefly last week, Dr. John AmbroseFleming, Professor of Electrical Engineering at Uni-versity College, London, is retiring after a connectionwith that institution which has lasted for forty-one

years.

meet interference so longas the service is efficiently con-ducted.. Presumably the Postmaster -General will be answerable to Parlia-ment for the efficiency of the service,but that is quite a different thingfrom Post Office .control, which mustbe avoided at all costs.

No Propaganda !And lastly, broadcasting must not

be used as a means of Government pro-paganda. We do not want a repeti-tion in this country of what hashappened in Russia. In SovietRussia, broadcasting is a Governmentmonopoly, as it will be in this countryin the future. And in Soviet Russiabroadcasting is looked upon as themost powerful weapon in the armoury

speeches of politicians and othermatter which the Government wishesthe people to hear. This kind of thingmay be very good from the point ofview of the Government in power, butit is certainly not good for the pro-gress of broadcasting; the temptationwill be very great to use broadcastingas a means of placing the views of theGovernment in power before thepeople, once the new Corporation hasbeen placed in control for ten years.

DangersI believe these are the points on

which listeners should concentratebetween now and the autumn, asafterwards it will be difficult for mis-takes to be rectified. It is all very

penceavoided.

Mind Your Fingers ?The centre punch is held

in the fingers by the milledcentre piece, and a sharptap with a hammer appliedto the top. Many bruisedfingers have resulted fromusing centre punches, butan almost infallible methodis, instead of looking at thehead of the punch, to lookat the point. " The naturalmovement of the arms, to-gether with the controlexercised by the nerves, willalways bring the hammerhead in the correct position.

SharpeningThe punch will, of course,

sometimes get blunt, and itmay be sharpened on anemery wheel or on a hard,very rough stone.

A good centre punchmade by any of the well-known tool manufacturers,Brown & Sharpe, Starrett,Goodell -Pratt, etc., willcost about one shilling; thecheaper variety sold at six -

by unknown makers should be

Another Satisfied ReaderSir,-I have been a reader of WIRELESS

from the first number, and even now Icannot repress a certain amount of sur-prise at the amount of useful matter thatyou can publish for 2d. every week.What strikes me most is the perfectbalance that you manage to preserve weekby week ; there is never an excess oftechnical articles or of the more practicalarticles. For me the balance is justright. --Yours faithfully,

J. L. DAVIDSON,Cleethorpes.


torn myrnichair

BY EARL lk.SELL.

In these columns Lord Russell expresses each week his own personalviews on matters of interest to " Wireless" readers.

Great CirclesI have been reading an excellent

account of the meaning of greatcircles and of great circle distances,but in one curious respect the writeruses language that might easily bemisunderstood, for he refers to Madrasas being due east of London becauseit happens to be on a great circlepassing through London. It is true,as is said in " The Snark,"

" What's the good of Mercator'sNorth Poles and Equators,

Tropics, Zones and MeridianLines? "

So the Bellman would cry : and thecrew would reply,

" They are merely conventionalsigns! "

And so they are, but it is well touse them in accordance with the con-vention, and by the convention dueeast and due west we mean places

situated on the same parallel of lati-tude. There are, of course, an in-finite number of great circles passingthrough London, and any place on theglobe is upon one of them.

B.B.C. ExperimentsThe two -station programme in Lon-

don seems to have disclosed .a gooddeal of lamentable weakness in crystaltuning; but, of course, a crystal thatwill receive very satisfactorily is notvery selective without a considerableadjunct of coils and condensers.Meanwhile the expiring B.B.C. is get-ting into trouble all round. One lead-ing article goes for it for constantlychanging its policy, so that manufac-turers never know where they are, andthe wireless trade has to be perpetu-ally scrapping, while another articleinquires where the high -power sta-tions are, what the real policy on thismatter is, and what the P.M.G. hasbeen doing.

Burnt -OutFew things are more annoyinE than

a burnt -out transformer in a com-pleted set. Even the generosity ofthe manufacturer does not make upfor the tiresomeness of having to pullinaccessible connections out and putthem in again.

What Is It ?In one of our most respected wire-

less weeklies I read a paragraph ofsuch discretion as to convey nothingto the reader. Let me see if I cartdo as well : " I am able to state onhigh authority that the project whichwas mentioned in a particular paperpublished in the North, relating to adevelopment that might be expectedin the wireless activities of a concernfamiliar to all of us, was prematureand unauthorised. The further state-ment as to the geographical characterof this new development, althoughrepresenting an arrangement of dis-tricts which will at once suggest itsorigin to the expert amateur, mustalso be regarded for the present aslacking in complete accuracy or cer-tainty" ! Perhaps a wireless readershould not have too keen a sense ofhumour, for in the same paper I seea reference to oscillating neighbourswho were actually " oscillating instep," and it is stated that experi-enced amateurs will recognise thesymptoms at once. It is quite certainthat experienced policemen would.

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I HAVE BEEN ASKED....

have a general purpose 3.valve re.ceiver, consisting of a tuned anodeH.F. valve, with reaction on to theanode coil, a detector valve, and onetransformer.coupled note magnifier.Although the set tunes in one or twoother stations fairly well, thelocal station, which is five milesaway, can be heard practically allround the dial, although maximumsignal strength is obtained at oneparticular setting. Can you adviseme how to improve matters?

Where a receiver does not tuneAharply on distant stations attentionShould be paid to the aerial and earthbestem, the insulation of the former

ing improved, whilst alternativesshould be tried for the latter. An in -

resting experiment here is to discon-feed the normal earth lead from theset and in its place connect a'length of

insulated flex, which may be takenthroughout the house, on the floor, toact as a temporary counterpoise. Ifwith this latter arrangement tuning isvery much sharpened, signal strengthis improved and reaction demands arevery much lessened, it is probable thatyour earth is partly responsible foryour difficulty.

At any distance less than eight milesfrom a main broadcasting station, orthree miles from a relay station, it ismost difficult to decide whether anysimple receiver is capable of tuningproperly and of receiving the more dis-tant transmissions, since interferenceis probably so severe that weak signalsmay be completely drowned. The bestprocedure to adopt is to employ awavetrap to eliminate the local pro-gramme, and the auto -coupled series

rejector type is suggested as being themost usually effective.

To construct this trap obtain a 2.inch length of 3 -inch diameter ebonitetube and wind on it 40 turns of 34 -gauge double silk -covered wire, whichwill take up approximately a windinglength of 1 inch. The winding shouldbe tapped at 5, 100, 15 and 20 turnsfrom one end. Across the whole coila parallel variable condenser of .0005should be connected. Join the aeriallead-in to one of the tappings on thecoil, the best being determined byexperiment, and join the end of thecoil from which the tappings arecounted to the aerial terminal of theset, in which latter parallel tuningshould be employed.

The method of operating the trap isas follows: First tune in a desiredtransmission without using the trap,employing ordinary parallel tuningin the set, and then bring the trapinto circuit, slowly rotating the trapcondenser until signals from the localstation disappear completely or arevery considerably reduced in strength.Leave the trap condenser set at thisposition and re -tune the desired trans-mission on the aerial condenser of theset. This may necessitate slight re-tuning on the trap condenser also, butonce this latter has been properly setit should not need alteration. Search-ing for distant transmissions may thenbe carried out in the normal way onthe controls of the set.

FROM A READER

Why Do We Use Different Ratios?SM,-With reference to the article

under the above heading in your issue forJuly 17, whilst the remarks given thereinare certainly interesting, yet_theydo not answer the question askedin the title of the article referredto.

It is, of course, obvious thatwithin certain limits of dimensionsthe higher the ratio the smallerthe primary inductance and conse-quent impedance at any particularfrequency, and vice versa.

The article in qubstion does notemphasise, as it should, the rela-tion of frequency to impedance, onwhich, of course, everything de-pends, and if one employs trans-formers in which only 70 per cent.of the maximum amplification isobtained at any particular point itfollows that their curves must beof the humped variety, seeing thateven the poorest transformer hasa very high impedance at itsresonant point, at which pointalmost 100 per cent. of the totalavailable amplification is obtained.

Another point which appears to thewriter is that the highest possible induct-ance and consequent impedances should beused in each stage and whether a trans-former with a lower impedance may beused in the second stage depends on theamount of distortion with which ono isprepared to put up.

In conclusion, I would ask a questionwhich I have asked on many occasions,namely, why should one use a valve oflower impedance in the first L.F.stagefrom that used in the detector ? My ex-perience is that the best results are to beobtained by using similar valves in bothdetector and first L.F. positions, providedthat one does not employ valves having animpedance greater than about 30,000 ohms.

The Elstree night watchman has still anfortunate penchant for valves, pieces of wire

other unconsidered trifles.If one uses a lower impedance valve in thefirst L.F. stages, as a rule one merely losesamplification, which loss it is endeavouredto make up by the employment of a high -ratio transformer, which necessarily has apoor amplification curve.-Yours faith -fu, JOHN BAGG s.

Manchester.

NOTES AND NEWS

ON August 7 Mr. Peter Chaney ispresenting "The Shadow Folk'-'

in an entertainment entitled " Picca-dilly Circus." This will be performed

in the London Studio.

un-and

ON August 15 the Rev. F. A.Jarman will give a talk on

London's underworld derelicts,including the " down -and -outs "who seelstshelter in the crypt ofSt. Martin's -in -the -Fields atnight.

* *

A. CONTEMPORARY is ask-ing what our old sets

would be saying to one anothernow if they could talk. Whatwith centre -tapped coils, neutra-lising condensers, slow-motiondials, screened coils and the like,,I don't think they would men -raise wireless at all, and, if theycould talk, I should not like tohear the language they used!

THE opera " Rigoletto,"was broadcast on July 7, is to be

repeated by the B.B.C. on August 20,On this occasion Boasey's version willbe employed.

CALL -SIG


C. R. Li4r.

Me," ....aw-A-..ormo.tsr..tvratenetete-ewose,,T

D C2 I.2r

B1 R2

oe

TIMMS BY TIIII SIVAITreeS an earnest student of the

advertisement pages of ourwireless journals I am reluc-tantly forced to the con-clusion that manufacturers

of radio goods are not nearly so open-handed as those who make or deal inarticles of other kinds. It is, forexample, quite impossible to open a laymagazine or a morning paper withoutfinding announcements from firms whoare positively dying to present youwith samples of cocoa or tooth paste oraerated breakfast oats or something ofthat kind. But have you ever comeacross, sate, a loud -speaker manufac-turer who is yearning to distribute freesamples of his wares? I trow not.

ParsimonyEven those who turn out quite small

like valves and transformers andrheostats seldomrespond in theright spirit if onepolitely suggeststhe sending of afree sample. Andthen again therea r e delightfullittle competi-tions got up by1 a y advertiserswith gloriousprizes if you aresuccessful. " Fillin the missingletters of thesethree well-known English towns," theycoo, " and if you are successful you willreceive ABSOLUTELY FREE as aprize a genuine simulation gold gent.'swatch." The only condition is thatyou should buy a handsome and inex-pensive chain to wear with it. I amstill looking for a wireless firm whichwill ask me to complete L -ND -N,17-11K, W -G -N, in order to win a five -valve set absolutely free so long as Ipurchase a pair of genuine flex 'phonecords for attachment to its terminals.

14.-..-4-11.-------------4.-4-4.------..................-4.-.............-..........................

4._I, '11,/[, i,,,....

11.4-4-4 - 4-4-4. --*- 4-4- 4-4-4-41.-4-4-4-11.-- ......-.41

The lamentable lack of faith inhuman nature of the wirelessmanufacturer - the same failingamong the members of the Little

Puddleton Wireless Club.

penny a month. The Smiling Mr.Sage, who winces slightly at the verymention of money, accepts the offer atonce, delivers the stuff by aeroplanewithin the hour, sticks up their wall-papers free of charge, and presentsthem with a free insurance policycovering all such risks as picture -hanger's thumb and the like. But wepoor wireless folk seem to be nobody'schildren.

it. . . Picture hanger's

thumb .

M

And Mr. Everyman !Think, too, of the happy couples

who require to furnish the little nestsin which they are proposing to settledown. They do not have to go andplank down hard cash. Not a bit ofit. They simply trot along to Mr.Savit Sage, choose what they want,and offer to pay two-and-ninepencedown and one-and-sevenpence-half-

tt. . Who winces slightly at the

very mention of money . .If

........-. -.1r- -41.4,-.0.11-11-4.-4.-4-4.1-4-4-4.4.--.4-4.-4-4-40-4,4-4,........111

So Simple !How jolly it would be if only we

could have interviews like that withMr. Churn -Bones or Mr. Squito Spot,for instance-. Mrs. Wayfarer u-ouldsay, " We hare so enjoyed lookinground your beautiful showrooms, Mr.Spot," and Mr. Spot, delighted to hearthat we had chosen the biggest set inthe place, would be charmed to takesimply anything (or even nothing atall) down, and Mr. Spot would tell menot to worry about paying the instal-ments if they were a bore, and Mrs.Wayfarer would burst into tears ofjoy, and Mr. Spot would deliver theset in a plain van, and Mr. Spot's menwould rig up the aerial mast free ofcharge, and we should all be jolly andfriendly and happy, and that would bethat.

Buggy Never Crows !Think, too, how awfully well off those

racing johnnies are. If ever theywant to make a bit of money theyjust go to see Mr. Bugless Skewheartand ask him if his rules will allowthem to wire their wagers ten minutesafter the advertised starting time.Mr. Skewheart murmurs, " Why, ofcourse; or the next morning for thatmatter, if it is more convenient toyou," and the thing is done. I some-times picture myself with shiny topperand beautifully creased nether gar-ments (instead of creased topper andshiny nether garments, as is moreusual with me), taking part in adelightful interview :-

" Good morning, Skewheart. Myfriend, Lord Blotto Bilger, was feel-ing pretty sick with his agent when Isaw him this morning."

" How was that, Sir Wireless? ""Well, you

see, Skewheart,the thought ofbacking Spavinin the three -thirty yesterday,but forgot tosend a wire, andhis agent refusesto pay."

" T t, tut,that is prettyhard lines."

" What wouldhave happened toa client of yours,

Skewheart, in such circumstances? "" In a case like that, Sir Wireless,

I always make a point of payingdouble the odds."

" Your usual fairness! That's whyI'm so enthusiastic about Buggy!

Really, it seems almost a shame totake Mr. Skewheart's money.

The DifferenceI should like to have pleasant,

friendly interviews of that kind withnever a carping word when I go downto the wireless club. The sort ofthing that actually does happen to mewhen I stroll in and find the Generaland one or two others there is this:

Me : " Evening, General."The General : Rrrmph ! "Me : " Evening, you fellows."Poddleby : " Where's that grid -leak

you borrowed a fortnight ago?';Snaggsby : " Yes, and how about



Jottings by the Way-continuedthe power valve of mine that you didin last week? "

Bumpleby Brown : " And haven'tyou nearly finished with the head-phones that I lent you two yearsago?"

Me : " Oh, don't let's bother abouttrifles like that; I've got somesplendid news."

They: ???Me : " I got WGY on the loud-

speaker last night with one valve."They : " LIAR ! "Though a peaceful person, I

naturally seize the heaviest com-ponents within reach and hurl themat their unbelieving heads. 'ihe clubhouse is instantly turned into a beargarden by these rough fellows andthe atmosphere of calm and dignitywhich should prevail within its wallsis gone.

How Beautiful 'Twould BeHow much more beautiful life would

be if only one's fellOw-members wouldshow a little of the sympathy, the under-standing and the Christian charitythat distinguish Mr. $kewheart. Some-times in my imagination I picture

" . Fling the heaviestcomponents within reach . .

them with changed hearts and see inmy fond dreams something like this :

Me (entering the club house):" Evening, General,"

The General: " Good evening, mydear fellow. How splendid of you todrop in."

Me : " Evening, you fellows."Poddleby : "Hullo, Wayfarer. I

have been longing to meet you. Ihave got half a dozen new valves thatyou simply must try out."

Snaggsby : " Oh, by the way, oldchap, I've got a new variable con-denser that is much too good for arotter like me, and I wondered if itwould be of any use to you? "

Bumpleby Brown: " That remindsme, I have far more components thanI want. Just drop in one eveningwith a sack, will you, and help your-self."

Me : " Oh, by Jove, I really mustreturn your . . . ."

Chorus: " Oh, please. don't bother,Simply delighted for you to have it."

Me: " I am afraid that you willhardly believe me when I tell p.,u that

I had Johannesburg oh a crystal atlunch time."

Poddleby : " Just shows what a realexpert can do."

The General: " No one would dreamof doubting your word."

Bumpleby Brown : " Heartiest con-gratulations."

Snaggsby : " A real credit to theclub."

And then I should look modest, andthey would pat me (not too hard) on

ON GUARD !

Mu's ardent desire to scale the newElstree lattice masts has to be checked.The " night-watchman" is here seenbeing brought back to the buildings

by Mr. Reyner.

the back, instead of swiping me over the ear with an earth tube, as they doin their present unregenerate state.

Oh, Frabjous Day !- Yes, this is the sort of spirit that I

want to see permeating wireless. Iwould like everyone's motto, exceptmy own, to be, " It is more blessed togive than to receive." I make an ex-ception in my own ease for tworeasons. In the first place, I am per-fectly willing to be less blessed by re-ceiving; and in the second, if therewere no receivers there could be no

givers, and nobody would be qualifiedfor the major blessing:

It is therefore quite in keeping withthe spirit of generosity and self-sacri-fice outlined in this striking articlethat I should be willing to sacrificethe joys of giving from the hardshipsof receiving. I reserve also the right

ff. . Just drop in

with a sack . . . "

to express my disbelief when otherpeople make absurd statements. Ithas been well said-I forget now bywhom; probably I said it myself-thatcriticism is the foundation of effi-ciency. If, therefore, there were notone critical voice raised in the clubhouse at times of need, the LittlePuddleton Club would soon show afalling off in efficiency, and thatnaturally would never do.

WIRELESS 'WAYFARER.

ANINTERESTING LETTER

Radio ContoursSIR,-Upon reading the article by

Captain E. A. Anson in the current issueon " Contours in the North-East Sector,"it occurred to me that the experimentsmight be taken a step further to ascer-tain if reception of broadcast from otherstations than 2140 is also of low degreeas compared with adjacent areas.

My. own experience is that the MarconiHouse stand-by transmitter gives muchbetter service to this district than doesthe regular 2L0 transmitter. This maybe proved by taking the test transmissionon Sunday at approx. 10.45 p.m. TheB.B.C. explain that any advantage wein the N.E. sector gain by the use ofthe Marconi House apparatus is so muchloss to districts in other directions.

From this it might be inferred thatthe cause was a directional fault of thetransmitting station, but then again thecase of " lucky Braintree remains un-solved, unless it be that elevation givesthem the advantage of stronger signals.-Yours faithfully,

A. MITCHELL.Ilford.

"MODERN WIRELESS " i

1/- AUGUST ISSUENOW ON SALE. 11-


N extremely simple andeffective tuner panel,such as is about to bedescribed, may be putto a varied number ofuses and is an acqui-sition essential to

those who indulge to any degree in ex-perimental work.

The panel is primarily intended foruse in conjunction with the " FlexibleReceiver," which was first described inWireless Weekly, April 7. It will beremembered that the receiver incor-torated four independent panels inhe following order :-

Panel A.-Tuner with crystaldetector.

Panel B.-Valve detector.Panel C.-First stage L.F. ampli-

fier.Panel D.-Second stage L.F. am-

plifier.This was followed in a later issue .ofWIRELESS, dated May 29, by the fifth

PANEL F.

REA.13/15"

rios

334.;

2i

6"Fig. 1.-Only the two condenser dials

appear on the face of the panel.

A Tuner Unit for the" Flexible Receiving Equipment "

By H. BRAMFORD

This tuner is specially designed for use in the unit -type receiver describedin "Wireless Weekly" for April 7 last, but it will be found a very useful

accessory for general experimental work.

unit, Panel E, which took the formof one stage of H.F. amplification.

A Flexible UnitIt is now, therefore, thought by the

writer to be advisable to add a further

PANEL F.

NOY/Ne

48

47

46045O44

43042

4/

Fig 2.-A special strip of Clix socketsis provided for inter - connection

purposes.44444444 444444refinement to this receiver in the shapeof a special tuner, which gives theadvantage of a useful degree of selec-tivity in addition to a considerable

R -FCHOKE

'000342

43

44

45

4i

47

048Fig. 3.-The colours indicated in thiscircuit diagram are those of the Clix

plugs.

number of possible tuning arrange-ments, including various forms of thepopular " Reinartz " circuit.

On the other hand, the unit shouldprove useful in itself as an experi-mental addition to any form of ampli-fier panel or for general use. The com-ponents which Were actually used for


The Clix strip is carried on two smallbrass angle pieces.

380 WIRELESS. August 7, T928.

.................................................

MOLLY -CODDLINGTHE B.B.C.

By PERCY W. HARRIS, 111.1.R.E., Joint Editor

A strong protest against the grandmotherly supervision exercised by the Post Office over all the topical itemsbroadcast from the B.B.C. stations.

OME time ago I knewa family which wasvery proud of itsyoungest boy. Greatpains were beingtaken to give him agood education-to

use the common phrase, " no expensewas being spared ' he had a specialnurse to look after him, and hisparents were particular, very particu-lar, of the company he kept.

An ExampleA few doors down the road lived

another' ilittle boy. Hisparents were proud of him,too, and, for their part,were just as anxious to seehim " get on." I mustadmit that he was rather apugnacious little fellow, andwhen one day in the courseof an argument he punchedthe first little boy on thenose, the indignation ex-pressed by the first littleboy's parents was almost toogreat for words. On noaccount must he play withthe naughty boy from downthe street! The next timethey met, an icy stare wasreturned for the friendlygrin, whereupon a secondpunch on the nose finishedthe friendship for all time.

And the ResultI saw both the boys the

other day (not together, ofcourse), and while thepuncher had turned `into a manlyyoung fellow, the punchee, carefullyguarded from all contaminating in-fluences, is one of the most priggishmolly -coddles I have ever met.

At the present time the BritishBroadcasting Co. is in great dangerof being molly -coddled in just thesame way by its guardian, the PostOffice, who are exercising their censor-ship rights in keeping from the publica number of " talks,' which, if fairly" strong meat," are at least fair-minded-, intelligent, and, I may say,

much more intelligible than some ofthe boring talks which are as devoidof interest to the great majority oflisteners as they are of harm. Onlya week or two ago it was arranged tobroadcast a dialogue on the AmericanDebt between Mr. H. D. Henderson,Editor of the London Nation, andMr. Raymond Cran Swing, Londoncorrespondent of the PhiladelphiaPublic Ledger, a highly -esteemedAmerican newspaper. At the lastminute a brief notice in the paperindicated that the dialogue would notbe given, the reason being that the

The idea of a dialogue between anintelligent Englishman and an intelli-gent American, both well versed inthe subject was a good idea,and, having read every word of thedialogue which was to have beenbroadcast, I feel that it would havebeen one of the biggest broadcast suc-cesses we have yet had. Two quitedistinct and separate -viewpointswould have been put forward, and, inmy opinion, nothing but good couldhave come from the broadcast. I haveheard many far more provocative andcontentious matters discussed " on

the air," and if this is tht;kind of talk which is to besuppressed under the new

Every item of the most remotely controversial nature under-goes the censorship of the Post Office.

Post Office had censored it in the goodold D.O.R.A.'fashion.

An Excellent IdeaNow, there are a whole lot of people

in this country who have very definiteviews on the subject of the British.Debt to America. It is not a dry sub-ject if properly treated. It affects usall in so far as taxation is concerned,it has a very real influence in ourlives, and, without any doubt what-ever, a great number of misconcep-tions exist on the whole subject.

regime, much of the in-terest of broadcasting mayevaporate.

Another VetoYou may think that this

is an isolated case, but I canassure you it is not so.Would you have been in-terested in a debate, at theLondon School of Economieson " Is the House of Com-mons any Use? " betweenMr. J. II. Thomas, M.P.,and Mr. G. K. Chesterton,with Mr. Lloyd George inthe chair? I am sure avery large number of readersof this journal would havelistened to it with pleasure,yet it was turned down bythe Post Office.

We have few enoughwitty speakers in these

days, and when their speeches havebeen broadcast they have provedsome of the most amusing items in theprogrammes. Many people wouldhave given a great deal to have beenpresent at the 70th birthday dinnergiven to Mr. Bernard Shaw. Why didnot the B.B.C. broadcast the speechesat the dinner, you may ask. The neces-sary gracious permission to do so wasnot granted by the grandmotherlyPost Office.

Wide PowersSo far as I know, the Postmaster-


A Strong Protest Against Post Office Meddling

General is the sole authority (otherthan the B.B.C., of course) to judgewhether or not the matter broadcastis suitable for our consumption. ThePostmaster -General himself and hishigh officials in power at any giventime are estimable people, and I havegreat admiration for them, but theabilities which have raised them to thehigh positions they hold are not neces-sarily those which make them fit judgesof what the public should hear bybroadcast. It is obvious that theBroadcasting Company must be pre-vented from releasing dangerousmatter, but I am sure the public didnot realise when broadcasting cameinto force that such wide censorshippowers would be wielded by the PostOffice.

A Good RecordThe other side of the question is

that there are many ways in which theBritish Broadcasting Co. could havemade a complete mess of things, quiteapart from the broadcasting of un-desirable discussions, but the historyof the Company shows that they haveused an admirable discretion. It is nosmall achievement to have successfullyconducted programmes for the lengthof time the present Company has donewithout causing serious offence in anyquarter, for it will be admitted by thebiggest critics of the B.B.C. that thefew slips have been of quite minor char-acter. After all, is it not worth a fewsmall risks for the sake of maintain-ing a good, active viriletone in the service? Ordo you prefer the molly-coddle method in which

highly improving " talkson such subjects as theHome Life of the Ant(which will do littleJohnny such a lot of good)are preferred to suchmatters as the wittyspeeches at the birthdaydinner of a great authorand dramatist? Possiblythe Postmaster - Generalthought Mr. Bernard Shawmight have used a naughtyword. which might shocklittle Johnny's ears.

An Important SelectionYou may say, of course,

what is the use of discuss-ing all this when we mustput up with it? Do notforget that at the end ofthis year importantchanges are being made,and it will be necessary tochoose the Commissionersfor the new broadcasting Commission.The choice of these Commissioners is avery important matter, and not onewhich we must allow politicians to

" CARTOONIGRAFS"COMPETITION

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See page 384

DO YOU REMEMBER IT ?

cranks and faddists, and it should bemade clear that the great NationalService of Broadcasting must beentirely free from the molly -coddlespirit in every shape and form. Wemust have the best possible broadcastservice, a choice of programmes to suitall tastes, and a complete absence ofthat patronising " We know what'sgood for them " spirit which animatesso many people who put themselvesforward in various places as guardiansof the public taste. The question ofcensorship must be considered verycarefully by the House of Commons,and the limitations of censorshipshould be clearly defined in draftingthe new arrangement. The publicmuch prefer a boy who is a little manand occasionally naughty, to the meek-and -mild molly -coddle dressed up in avelvet suit and a lace collar, with aLittle Lord Fauntleroy hat.

" Cutting "I have purposely refrained in this

article from referring to all of thetalks that have been censored, norhave I referred to the number of caseswhere, in talks which have actuallybeen given, considerable proportionshave been deleted'by the censor. Thosecases to which I have referred abovehave been of complete censorship, thematter submitted being vetoed as awhole.

Finally, I' have more than a sus-picion that some of the censoring bythe Postmaster -General has been car

r i e d out under the

One of the first occasions on which wireless wasused for controlling a moving object was when

this model airship was directed by radio.

undertake without consulting allinterests concerned.

The new Conunissioners must bebroadminded men and women, not

impression that anythinggoing out from a broad-casting station will belooked upon as an officialpronouncement o f 't h eGovernment's vi e w s.Whatever may happen intimes of National emer-gency, in normal times theBritish Broadcasting Com-pany (and the BritishBroadcasting Corporation,which is to take its place)must not be looked upon asa Governmental body, and,indeed, the Postmaster -General, in his speech uponthe Post Office estimates,was at some pains to im-press upon the House thatthe broadcast service wasto be looked upon as some-thing divorced frompolitics.

A SafeguardFortunately, in the

House of Commons we haveCaptain Ian Fraser on

the one side and Commander Ken -worthy on the other who, I am sure,will do their best to safeguard the new,Corporation.


I SHORT-WAVENo/es &News

NCE again the honours of thefortnight seem to have gonealmost completely to thelow -power stations. This isnot surprising, however, in

these days, as the higher -poweredstations have already covered all theavailable " DX," and are turningtheir attention to reliability tests andschedule work.

The Brazilians continue tocome through in large num-bers at any time after 10.30p.m., and various Europeansseem to be able to work themwith almost any power, andalso to -" raise " them withone short call. Apparentlythe standard of reception inBrazil is high!

A Good EffortThe best report, however,

comes from G -60H, who re-ports two-way work with theU.S.A. with an input of 2.5watts, without a schedule.There are, of course, very fewstations who have, as yet,worked. America with so lowan initial power... It is,naturally, much easier to calla station on, say, 20 watts,and then to reduce power toa very low figure withoutbeing lost by the otherstation.

Star ReceiversApparently there are a few

American stations with par-ticularly good receivers, orelse they are situated veryfavourably for the receptionof European signals. Mostof the British low -power sta-tions who have " got across "at all seem to have workedU-2CVJ, and many othershave been' in communicationwith U-1CH and U-1CIB.

GI-6YW, one of the low -power" stars," has now worked Canada andU.S.A., in addition to his famous workwith Porto Rico on 2 watt! With6 watts input he has recently worked-C-lED, GX-&MU (when 850miles West of Valentin), as well asLA-lA and an Austrian station. Oncemore, why use more than 6 watts?G-5WV also has worked various -

Americans and Z -2A0 with inputsvarying from 8 to 1.1) watts.

Telephony StationsWe have received several reports of

reception of short-wave telephony fromAmerica. Quite a number of theshort-wave experimental broadcaststations are working qiiite regularly,and we hope to be able to publish de -

Our cover photograph this week shows one of theframe aerials on the top of Bush House which isused by the U.S. Shipping Board for receptiondirect from their headquarters in the States.This photograph shows the short-wave trans-mitter at Bellevue used for despatching some of

the traffic to England.

tailed information as to their wave-lengths in the near future. WBZ(Springfield, Mass.) is apparently oneof the best stations, judging from thenumber of reports mentioning him.The wavelength used is 49 metres, andanother station, most probably 2XG,is on 48 metres rather irregularly.WGY's crystal -controlled transmitters(2XAF, 2XAD and 2XK, etc.) work

on 32, 26 and 16 metres, and areeasily recognisable by the purity oftheir telephony. Apparently thecrystal control has the effect ofeliminating some of the so-calledaudio -frequency fading, which is oftenmistaken for " night -distortion " IOne correspondent reports receivingthe 32 -metre transmission on a loud-speaker with a crystal and three stages

of low -frequency amplifica-tion !

Apparently there has beena misunderstanding about theaddress of 2XG, which is notone of the WGY stations, aspreviously stated, but the ex-perimental station of the BellTelephone Laboratories,Ocean Township, N.J., U.S.A.

The AntipodesThe New Zealand and

Australian stations have com-pletely disappeared at thetime of writing, but it is morethan: likely that they will beback in full forte before thisappears in print. In themornings at about 6 a.m. alarge number of " odd " sta-tions are working, includingthe American commercial sta-tions, NAL, NAW, NKF, andsome of the ships in thePacific waters, such as NEQQ,N,AjD, and Many others,PI-3AA has also been heardat this time, but none of theAustralasian stations havebeen strong enough to read.

-As far as -can be foretoldfrom the present weather con-ditions and the general trendof events lately, it seems thatEuropean stations are gradu-ally fading out until late inthe evening, and Americanand other " DX " stationsimproving steadily. Probablythe autumn will be the besttime for long-distance work,

though not so good for Europeancommunication.

Send yourQRA Queries to Us

We have a special department whichdeals with them promptly.


Readers' Views and Comments

A ProblemSir,-I wonder whether any of your

readers have experienced a curious diffi-Culty that has been puzzling me for sometime. If so, perhaps they will be ableto help me to solve it. I have a four-Nalve receiver built to a design givensome time ago in IVireless 1Veekly,which has given me wonderful resultsfor several months. I have been morethan pleased with it until about a weekago, when it suddenly began to emitscratchy noises. More by luck thanjudgment, I found that these noisesceased completely when the aerial was re-moved. This naturally led me to suspectthe aerial, but when I made a singlevalve set somewhat hastily and attachedit to the same aerial, there was no tracea noise whatever. Back went the four-valver, and-back came the noise ! Iwas removing the aerial at the switch,which is close to the point of entry atthe window. Can the unpleasant noiseshave anything to do with the aerial, orare they due to a fault in the f our-valver, which only asserts itself when theaerial is in use?

Yours faithfully,Chessington. GEO. L. GREEN.

An AppreciationSir,-May I be allowed to thankWave -Trap " for his interesting and

amusing reviews of the week's events in

" The Week's Diary " ? I find this oneof the best regular features in WIRELESS,and I know of many others who turn tothese pages first.

Yours faithfully,H. J. CIIDDON.

Ilfrcombe, Devon.

" S.L.W." or " S.L.F." ?Sir,-May I be allowed, through the

medium of your Rapes, to voice my apple -elation of articles of the type of" S.L.W. or S.L.F." by Mr. J. H.Reyner in your last issue? WIRELESShas never neglected the beginner in radio,but he still wants many explanatoryarticles of that type, and I look forwardto reading many of them in the nearfuture.

Yours faithfully," OLD -BEGINNER..

Staines, Middx.

A SuggestionSir, Why does not the B:B.C. relay

WGY and the American short-wavestations more frequently? These trans-missions of theirs have always been verypopular, yet when they have one of thebest opportunities of doing this (WGYis excellent just now) we hear nothing ofthem. If I can receive WGY on a largeloud -speaker with a two -valve receivermade to one of the last 1Virelex8Weekly designs, surely the B.B.C.

should do great things with their elabo-rate listening -post at Keston.

Th it another question of " Get OnWith it "?

Yours truly,W. 0. JAMES.

Ludlow, Salop.

AMATEUR TRANSMITTINGNOTES

QRA's WantedOCTN, SPM, D-7XU, D-7ZG, DGN,

L6C.

QRA's FoundG-2BOC: A. C. Porter, 1A, Manor

Road, S.E.4.G-GCQ G. Sauter, Blackfriars

Foundry, Elgin.G-2BAN A. R. Gardiner, " Ash-

leigh," Abbots Langley, Watford.: A. Marcella Via 20 Set-

tembre 89, Rome.MAW Roberto Nessi, 13, Via

Guiseppe, Verdi, Milan.

Cards HeldWe shall be glad to receive any in-

formation which will help us to tracethe owners of the following cards,whose QItAs are at present unknown:

GBZ, R-DD7, , X-6XI, G-6CM,X-GB2, BE-1AX, D-PK7, GCA,G-3WK, G-6CR, GBM, A-5KN, PKZ.

' .e II I I I

I 11 I I I I I I I I I I

'FORM°auu putt/ C

ULTRA LOW LOSSStraight Line Frequency Condenser.

Cone bearings. Braced Vanes. PositiveCollector. A real precision job.

Condenser only-0003 r.LF, T005

Condenser with plain dial. 1016Standard 1- dia. ShaftSend for Catalogue and DescriptiveLiterature of Complete Formo Range.

THE FORMO COMPANY,CROWN WORKS, CRICKLEWOOD, N.W.2.

'Phone Vamp. 1787.Manchester : Mr. I. B. Levee, 23. Hartley Street.

Levenshulme. Phane a Beaton Moor, 476.See page 398 for Formo

Transformer.

9/ -

One Rheostat with two uses!

THE "PEERLESS"DUAL RHEOSTAT

3/9

This "Peerless" Dual Rheostat (as illustrated)covers the needs of both bright and dullemitter valves. It has two windings, one of aresistance of 6 ohms, and a continuation ofthis on to a 30 ohm winding. The resistancewire is wound on a hard fibre strip under greattension and is immune from damage. Thepopular one -hole -fixing method is provided,and the terminals are conveniently placed. Thecontact arm has a perfectlysmooth silky action.All the metal parts are nickel -plated. Com-plete with ebonite combined knob and dial.

From your dealer or direct. Traders requested to apply far Trade Terms.

THE BEDFORD ELECTRICAL & RADIO CO., LTD.22, Campbell Road, Bedford.

? CHOKE COUPLING ?

FERRANTIAUDIO FREQUENCY

TRANSFORMERSTYPE AF3

GIVE ALL THE AD-VANTAGES CLAIMEDFOR CHOKE COUPLING

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HOLLINWOOD,FERRANTI LTD., LANCASHIRE.


di)

(con+)NEW i-ASCINATIN6 COMPETITION WRIn WILL APPEAL TO ALL.

By ERN SHAW, the " Wireless" Cartoonist.The Prizes Offered in Connectionwith this Competition will be

found on page 381.

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" Hello ! Everybody ! " he'll say,In his humorous broad Yorkshire

" You know it's all wrong !Blossom says before long

way.

No. 8. --JOHNNOTE.-It is advisable to follow the instructions

drawing in ink. Black letters denote nebe drawn to the centre of the square.

Draw a continuous linefrom M4 to K4

K4 to E3El to C4C4 to A8AS to A13:A13 to D16D18 to bottom right

corner R16Bottom right corner

H18 to .1417G17 to E17E17 to C16C16 to B14B14 to B8B8. to C5C5 to bottom left

corner 114

Bottom left corner 114to top left corner 113

Top left corner HWto11 to L2L2 to M3M3 to M4M4 to 0505 to P6P6 to 11,7R7 to SW89 to 811511 to R131113 to P14P14 to 015015 to MI6M16 to K16K16 to top right corner

118

HENRY.in pencil first, and thenw lines. Unless otherw

Top right corner 116 totop right corner 1117

Top right corner 1117to 119

119 to L18L18 to 1817M17 to M1.6J3 to 1313 to top left corner 13Top left corner 13

to 1212 to L3J17 to 117117 to top right corner

117Top right corner 117

to I18118 to L17

carefully complete theise stated, lines should

L9 to bottom left*orner L9

Bottom left corner L9to M9

M9 to top right corner119

Top right corner MO toMIO

M10 to top right earnerM10

Top right corner 1110to M11

M11 to top right corner1111

Top right corner Amto L11

From bottom leftcorner 010 to M10

WHAT TO DOAll you have to do is draw a few lineson the chart and write one line to com-plete the limerick. If you oarefullyfollow the instructions_ given below anamusing picture will appear on the chart.Draw this in ink and then complete thelimerick with the wittiest line you -can thinkof and send along to " Cartoonigrafs,"Radio Press, Ltd., Bush House, Strand,to reach here not later than first postTuesday, August 10. Employees of RadioPress, Ltd., are not eligible. All com-petitors, by entering. agree to abide bythe decision of the Editor, which isfinal. No correspondence can be enteredinto regarding this Competition.

FOLLOW THE DIRECTIONSCAREFULLY

Send this whole page complete with yourI drawing in ink and your last line off the

inkick with .your name and address written

(blockletters) in the spaces provided.

I Name

I Address

I

Post to :-"CARTOONIGRAF8,"RADIO PRESS, LTD., Bush House,

I OPSTRAND, W.C.2.

To arrive first post Tuesday, Aug. 10.

-

1810 to bottom rightcorner 010

07 to 0808 to POPO to PllP11 to 0.12012 to 013011 to bottom right

corner 09Bottom right corner 09

to bottom rightcorner 010

Bottom right corner010 to 012

L5 to M6116 to NO$14 to 11141114 to L15R7 to bottom right

corner TOBottom right corner

T9 to T6T8 to top right corner

116R13 to bottom left

corner T11Bottom left corner 111

to T14T14 to top left corner

R.14From bottom left cor-

ner '114 to T14

T14 to. 015015 to. Q16Q16 to bottom right

corner 520From bottom right

corner T6 to centreT6

T6 to 0505 to Q4Q4 to bottom left

corner Si18 to F17H7 to 1818 to IS112 to ma1113 to 114114 to 112

The following linesshould be thick

05 to top right corner06

Top right corner G6to bottom rightcorner G8

015 to top left cornerG14

Top left corner 014 tobottom left corner012

Shade in hair andcoat


IN my last article I discussed thequestion of special variable con-

densers giving linear relations betweenthe dial readings and the oapacity,wavelength or frequency, as the casemight be. I also indicated that therewas a fourth type of condenser which,although by no means common, wasbecoming of increasing importance.This " logarithmic " condenser, as itis called, is of special value in caseswhere it is desired to match severaltuning circuits so that their dial read-ings are identical. In order to under-stand this it will be as well to considerwhat is required in the matching oftwo tuned circuits.

The ConditionsLet us assume that we have two

inductances both approximately equal,and that these are being timed bytwo variable condensers. It is desiredthat the dial readings of the variablecondensers shall be the same when thetwo circuits are in tune, irrespectivewithin limits of the actual position onthe condenser. In other words, thetwo condensers shall rotate both to-gether as the two circuits are tuned toincreasing wavelengths.

Let us assume that one inductanceis slightly smaller than the other.Then the capacity which is tuning thesmaller inductance will have to beslightly larger. Can we compensatefor this difference in the condensersby having a small fixed capacity acrossthe other condenser, so bringing thetwo dial readings equal?

"Balancing " UselessThis arrangement will be quite satis-

factory at one particular point on thescale, but it will not apply at anyother point. The reason for this caneadily be seen. The wavelength towhich the circuit tunes is proportionalo the product of the inductance andhe capacity. If this one inductance isfnly .9 times as large as the otherne, then the capacity with which it isuned must be approximately 1..1 times

as great. We can, if we choose,adjust both condensers to the samet-alue "(and consequently the same dialLeading) and add a small parallel cap_a-

ty across one of -them, making thetal capacity 1.1 times that of the

Other.

DO WE NEED A NEWCONDENSER ?

By J. H. REYNER,B.Sc. (Hons.), A.C.G.I., D.I.C., A.M.I.E.E., Joint Editor

It will easily be seen, however, thatthe value of this balancing capacity isnot fixed. It has to be a certain pro-portion of the total capacity in use at

The use of double condensers for thesimultaneous tuning of two circuitsinvolves many problems concerning the

shape of the plates.

any time, so that as we increase thecapacity of the condensers we mustincrease the, value of the balancingcapacity in order to maintain one con-denser at a value of 1.1 times that ofthe other. Consequently, the methodbalancing up the circuit by the addi-tion of a small capacity is not apractical one.

Balancing the DialsAnother alternative would be to

adjust both condensers to tune to agiven point in the middle of the scale,and then to alter the position of thedials until they both gave the samereading. Such an arrangement wouldgive an approximate correction, but'Would suffer from the same disadvan-tage as that just discussed.

In such a case we should have

balanced up the circuit by making thevalue of one condenser 1.1 times thatof the other. Obviously, however, itdoes not necessarily follow that thisrelationship between the two con-densers will hold over the whole of therange. In fact, with a circular platecondenser it would behave in a totallydifferent manner, and would be equiva-lent to adding a small fixed capacityonly, which, as we have seen, is not apracticable solution. -

What is RequiredWith condensers having specially

shaped plates to give an " S.L.W." orS.L.F. ' law the -actual relation

would be somewhat complex, but it isobvious that, with plates designed forsuch a law, no accurate compensationof the character required could be

A little consideration will show thatwhat is really required for an accuratecompensation of this type is that theeffective proportional change of capa-city for a given movement of the con-denser shall be the same over the wholescale. This means that if we movethe condenser a sufficient number ofdegrees to make its capacity 1.1 timesthat of the other, then its capacitywill remain 1.1 times as great as theother condenser, at equal dial read-

,SOVARE EA W

......:1114"S.'4".

106Aoiriefroc

OS.L.E

These are the three types of condenserplates discussed by Mr. Reyner. The"s logarithmic" type possess importantpossibilities in cases where it is desiredto use " gang control" of a series of

similar tuned circuits.ings, over the whole range of the two.Obviously such a device gives an easyand simple method of correcting anylack of matching in the circuits them-selves.



Do We Need a New Condenser ?-continuedAn Existing Type

It is quite possible to make up acondenser to obey such a law, and, infact, instruments of this type havebeen used in certain specialpieces of apparatus formeasuring the " decrement "of tuning circuits. The de-crement of a circuit is ameasure of the ratio of itsresistance to its inductanceat a given frequency, and in-struments can be devised toread this ratio directly.Calculations in such casesare greatly facilitated if acondenser obeying thisspecial logarithmic law isused.

It is not necessary to godeeply into the theory ofsuch a condenser. I proposesimply to compare it withthe existing types of con-denser, from which variousconclusions wilt be drawn.For the benefit of - thosereaders who are interested,however, I will give theformula from which theactual shapes of the platesmay be deduced.

The Formula

occurs right at the minimum of thecondenser where the square -law plateis curved round to give an almostnegligible minimum capacity, while

An Important PointThese differences, however, are com-

paratively small, and over the workingrange the -curves are very similar.

This is a most importantpoint. It means that theexisting type of " S.L.W."condenser is inherentlysuited for matching a num-ber of tuned circuits.

The usual practice in suchcases is to tune in to a sta-tion about the middle of therange. If the dial readingsa r e found to disagreeslightly, then the dials them-selves may be rotated on thespindles until the readingsare alike.

" C.W." AT SEA

The use of continuous wave transmitters for long-distance maritime work is increasing. This view

shows the equipment on a large Italian liner.

As the dial reading on the condenserincreases, so the radius of the movingplates increases in a certain propor-tion.

In laying out the shape ofthe condenser plate we aromore concerned with theangle between the zero lineand the particular pointunder consideration. If wecall this angle A, then the;radius of the condenser plateat that point must be

r= .\/ 2 c. E". + 1.2This formula is only given

for reference purposes. Thediagram shows the type ofplate which is obtained witha condenser of this sort.

There is always a certaincapacity in circuit even atthe minimum, which is anessential point with thisclass of condenser, in orderthat the correct proportionallaw may be obtained.

The, diagram gives an in-teresting comparison be-tween this type of instruwment and the " S.L.W."and " S.L.F." types. Itwill be observed that theshape of the logarithmiccondenser approximates veryclosely to that of the square -law or" S.L.W." type.

The DifferenceThe only considerable difference

the logarithmic plate falls off moregradually to a definite limiting value.Towards the maximum also there is

A Sound MethodHitherto such a procedure

has been regarded with somesuspicion, it being felt thatthe correction thus obtainedwas not an accurate one.It now transpires, however,that any errors introducedby 'this were of minor im-portance only-at any rate,over the majority of therange.

Reverting to the questionof new types of condenser, therefore,we can summarise as follows :-Theavailable condenser giving the best

all-round service, having re-gard to the spacing of thevarious stations, and thepossibility of matching intuned circuits, is the square-law or " S.L.W." type.A Possible Development

The possibility of beingable to tune several circuitswith one dial only is onewhich is meriting seriousconsideration to -day. Insuch cases the question arisesas to whether the square -lawplate is sufficiently accurate,or whether a more accuratecompensation is desirable.A Working CompromiseIt may be that the loga-

rithmic condenser will ulti-mately supersede the square-law type. Since the twocondensers are similar ingeneral form, the distribu-tion of the various 'stationsaround the dial would bolittle different from that withan " S.L.W." condenser.

On the other hand, themore accurate compensationafforded with the logarithmictype would be of considerable

assistance in many cases.This, however, will remain to be

seen, and for the present the existingsquare -law condenser serves very well.

WIRELESS IN THE FIELD

Rapidly transported wireless sets play a vitalpart in modern warfare. The photo shows oneof these equipments undergoing its final tests.

A petrol motor supplies the power.

some difference, the capacity with thelogarithmic condenser increasingsomewhat more rapidly than with thesquare -law type.


** ************************* *************

PRACTICAL TOPICSBy G. P. KENDALL, B.Sc., Assistant Editor

A Puzzling Case-An Old Trouble-Removing FluxLeakages.

IHAVE recently been spendingseveral more or less happy even-

ings chasing elusive crackles in a six-yalve receiver made by a reader fromone of my designs in Modern Wireless.The fault Was one which proved ex-ceedingly difficult to find, all the usualtests failing to give any indication ofits whereabouts, and the whole episodewas an interesting reminder of thefact that one particular cause ofcrackling noises has very largely beeneliminated by the change in. ourmethods of set construction.

The ExceptionI tried all such things as replacing

transformers whose windings might bebecoming defective, testing valvesockets, and so on, but at no time didI think it worth while to look for thatonce common cause of noise, namely,an ebonite panel badly splashed withsoldering flux.

In the days when we used to buildour sets all upon one panel, and whensome people made a habit of reversingthe set and soldering directly abovethe panel with a very hot iron andquantities of flux, it was quite acommon thing, and indeed it was oneof the first to be tested for, to dis-cover that the trouble was purely amatter of surface leakage on the backof the panel.

An Indirect GainThe present method of arranging

sets with only a very few componentsupon the vertical panel and the greatmajority of the others in the form ofindependently insulated units upon awooden baseboard has practicallyeliminated this source of trouble.Splashes upon the wooden baseboarddo not matter very much as a rule,and such soldering as is done upon thecomponents which are actuallymounted on the panel takes place,generally, some little way off theebonite itself, and moreover is notdone directly above it, so that splashesdo not fall upon the surface of thepanel.

A Dangerous MaterialFlux splashes, as a matter of fact,

may produce quite low resistance leaksat times, for although some of thecommoner soldering pastes are quitegood insulators in their original con-dition, once they have been wellsinged by the soldering iron theybecome quite passable conductors.

One does not often come across aset in these days which is entirelybuilt upon one panel, but such instru-

ments are still occasionally con-structed, and it may be of interest toremind my readers of the methods tobe adopted when it is discovered thatflux leakages are taking place uponthe ebonite, because unless one knowsthe special tip, such troubles arerather difficult to remove when thewiring is rather complicated.

The RemedyThe best method which I know of

removing such leakages consists in theuse of some solvent for the solderingflux, such as petrol, with which theback of the panel should be liberallywashed, and at the same time scrubbedwith the aid of a stiff paint b11.Such treatment must be reallythorough, but no fear need be enter-tained as to damage to the ebonite,for although the back of the panel willbe slightly discoloured by the treat-ment, its insulating qualities shouldnot be impaired.

Accumulator Tops AgainA reader has been good enough to

write to nie pointing out that my re-cent remarks upon the subject of thewashing of accumulator tops to re-move the accumulation of acid spray,dust, and so on, might well have in-cluded a hint which is often given bybattery makers for the treatment ofsuch deposits.

The tip in question is simply to usea dilute solution of ammonia for wash-ing the battery, thereby neutralisingthe acid, and rendering it somewhateasier to wash off. As a matter offact, however, I do not employ thismethod myself, because a properlymaintained accumulator should notget so dirty as to require the use of aneutralising agent to restore it to aproper condition. If the washing isdone with clean water at sufficientlyfrequent intervals, no very great accu-mulation of acid should ever beallowed to take place.

A COMMON QUESTION

Can I use an H.F. transformer insteadof a neutrodyne unit in an H.F. anddetector set?Yes, provided your H.F. transformer

is of barrel type, with suitable couplingbetween primary and secondary wind-ings. The secondary winding, whichis generally larger than the primary,should be employed for the tunedanode coil and the primary windingshould be utilised for the neutralisingwinding. J. U.

pi% "-

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383 WIRELESS. August 7, 192o.

WEDNES

747

RI SA 1"

- .

WEEKS DIAR0 BSERVERS reclining in punts

along the shady banks of theRiver Thames were mildly interestedto observe on Saturday, the 24th ofJuly, a steam launch proceedingleisurely up -river with a particularlyhappy party on board.

" I seem to know thatface ! " observed a languidyouth to his fair companion,referring to a figure on deck.

" Yes, I think I have seenit in the Mirror somewhere,"came the equally languidanswer. " Some music -hallstar, I suppose."

As a matter of fact theparty In question comprisedthe majority of the staff ofRadio Press, Ltd., including,of course, the highly talentedcollection of geniuses who areresponsible for this journal,who were taking their annualouting to Marlow -on -Thames.After a luncheon which musthave left a very small profitfor the hotel proprietorsconsidering the quantitythat was consumed, theparty adjourned to a near -byfield, where all kinds of non-technical sports were in-dulged in with great gusto.

INTERESTED parties whosaw Mr. Scott -Taggart

excitedly urging the tug-of-war team to still betterendeavours and Mr. Harris'sfrantic attempt to win thesack race remarked that theydid not think such wirelesspeople could he so human.

By way of a change, thevisitors were given an oppor-tunity of hearing the localloud -speaker at work. Afterabout three seconds' audi-tion, several technical mem-bers of the staff disappearedinto the building, sought outthe set, and promptly remediedseveral obvious defects in reproduc-tion. Having performed this " dailygood deed," they returned and joinedthe dance which had been organised.Tired out but very happy, the partyreturned to London, and they havefelt very much better for the outingever since.

Incidentally, I am able to show you

below on this page a photograph ofMr. Harris, who, being a very keenamateur cinematographer, spent agood deal of the time filming all andsundry in and out of the sports. Thedemonstration of the finished film iseagerly awaited.

1171,rtrrnm.rtnnertrrfnli

action against the Zenith people andpromptly lost, whereupon the latter,finding that they were at least tem-porarily freed from restriction,adopted, in common with others, a" go -as -you -please " policy. Untilnew legislation clears up the

matter, American broadcast-ing stations are doing justwhat they like, and chancingto luck as to whether theyc a u s e interference. InNovember, when Congressmeets again, one can expecta new measure to be rushedthrough, giving full autho-rity to the Secretary ofCommerce to regulate thestations. Until then thechaos is likely to continue.

THE STALKER STALKED

At the recent Radio Press staff outing Mr. Harrismade good use of his kinema camera. He is

seen here watching his chance.

SINCE the Zenith in Chicago,with their station

Co.,VJAZ,defied

the edict of Mr. Hoover, the Secretaryof Commerce in the United States,and calmly began to broadcast on awavelength different from that allottedto them, all kinds of things have hap-pened in the American ether. As Ihave mentioned on a previous ocea-

_sion, the Government brought an

I SEE there is an outcropof complaints regarding

annoyance caused by loud-speakers. It is surprisingthat although it is bothcheap and easy to obtainreally good -quality repro-duction on the loud -speaker,so many people not only putup with inferior reproduc-tion, but actually consider itis the best that can beobtained. 9nly the otherday I met a good lady whoannounced that she wasgoing to fit a wireless set inher home. " Of course, Ishall have to put in a crystalset. Loud -speakers are sahorrible, aren't they? " shesaid.

A few nights before I hadmet a well-known businessman who held just the sameviews, and I found oninvestigating that his pooropinion of loud -speaker re-production had been gainedfrom the awful soundsemitted by a bicycle shop

which he happened to pass everynight on his way home from thestation.

* *THE Wireless Societies, which are

not usually very active in thesummer -time, might well call emer-gency meetings for the purpose ofgiving demonstrations to the public ofreally pure loud -speaker reproduction.

august 7, 1926. WIRELESS. 389

The Week's Diary-continuedMika this is done all kinds of absurdideas may be held by local councils.Vor example, I see that at Sidcuprecently a Councillor spoke of " thefearful menace which is overtakingthe district by so many resi-dents letting loose thoseawful loud - speakers." Isthere no Sidcup reader ofthis journal who can giveCouncillor R. Ellison ademonstration of how excel-lent and pure reproductioncan be with inexpensiveapparatus?

THE real trouble comesnot from loud -speakers

as loud -speaker's, but fromthe absurd attempts ofmany people to get fromthem far greater volumethan they (and the sets usedwith them) are designed togive. No person has a rightto " show off " his apparatusby seeing how far he canmake it heard. A properlycontrolled loud -speaker neednot be an annoyance toanyone.

" Elstree Five." Mr. Reyner and I,the other evening, found twenty-sevenstations on this instrument between 5degrees and 90 on the dial. Thisparticular set is only one of the many

you will guess there is something novelabout it. But when I tell you thatselectivity is far in excess of anythingelse Mr. Harris has yet produced,and that as for its sensitivity we

were able 'to get full loud-speaker strength from, a Ger-_man station on the earth leadalone, I know you will be stillfurther interested.

Incidentally, it can bebuilt and equipped with allaccessories, including valves,accumulator, high - tensionbattery, and loud -speaker, for£20, and is a handsome addi-tion to any drawing -room. Inoticed a large number ofingenious simplifications ofconstructional work whichwill be widely welcomed bythe home builder. There are,for example, only five holes tobe drilled for mounting thecomponents on the frontpanel. Can you guess whatthese five holes are? Threeare for one -hole fixing vari-able condensers, the fourthfor a one -hole fixing on -and -off switch, and the fifth-well,

ON THE RIVER

Part of the staff outing referred to by the Diaristwas a river trip, on which this snap of Mr.

Scott -Taggart was obtained.

IHAVE found it again ! Here it is,straight from a daily paper:-

" Viscount Wolmer, Assistant Post--General, said the science of

wireless telegraphy was still in its in-fancy." Fancy that now! Whatwonderful people our legis-lators are ! Remember I amnot quoting from a Parlia-mentary report of twentyyears ago, but from the pro-ceedings in the House on the21st of July.

IN common with manypeople, I was very dis-

appointed at the Jazz Debatefrom 2L0. Neither side" made a case " and therewas no real argument. Per-sonally, I like some of eachkind of music, and the respec-tive good points of classicaland jazz music were notmade by either side. Inci-dentally, I did not admireJack Hylton's choice of whathe called " representative "pieces. However, the . jokeabout jazz being described as." jumping from one bar toanother " was worth hearing.

special features in the SeptemberDouble Number of Modern Wireless,and the instrument itself will beshown at the Olympia show.

* *THE " Nighthawk " receiver-Mr.

Harris's latest set to which I

I mustn't give all the secrets away IThe " Nighthawk " is to be a

feature of the Wireless Constructor,which will be published on the 15thof September.

FADING

Much work is being done at the U.S. Bureau ofStandards on the problem of fading, special

recording apparatus being used.

THE Elstree Laboratories have beenworking night and day on, not

one but several, remarkable new re-ceivers. Have you ever sighed for aninstrument which would enable youto do all your tuning on one dial?The Elstree Laboratories have pro-duced just such an instrument in the

referred in these columns some weeksago-has now been completed, and Iwas allowed to hear it working theother night for the first time. WhenI tell you that it utilises quite a newcircuit arrangement, and although itis a five -valve set, uses an ebonitepanel measuring only 16 in. x 8 in.,

AMERICANS have notbeen long in finding

out the remarkable new seriesof receivers tp rod uced byRadio Press, Ltd., and oneof the leading American wire-less journals is already tellingits readers about the " ElstreeSix " and publishing photo-graphs and wiring diagrams.It is an- open secret thatin the past British wirelessreceivers have suffered incomparison with the Ameri-can, at least so far as selec-tivity is con-erned, but thetables are now being turned,and attention is being con-centrated on England.

:*

COMMANDER KEN-%, -.4 WORTHY'S suggestionin the House of Commons thata picture of the Postmaster -General and a hammer shouldbe placed in every public 'callbox, so that callers could finda better outlet for their rage

than the instrument itself, is worthadopting in wireless circles. Anice picture of the ProgrammeBoard, mounted on cork, and pro-vided with a set of good sharp pins,might afford an outlet for our feelingswhenever the programmes do not comeup to our own private standard.


IN last week's review I dealt withsome special amplifier valves con-

structed by Dr. Loewe, of Berlin_ Two other interesting products havebeen constructed at the Berlin Labora-tories which will be of interest to ex-perimenters in this country. The firstof these is a completely enclosed gridleak.

Progress in ResistancesOne of the great difficulties with

high resistances for use with wirelessequipment is the problem of maintain-ing constant values. The constructionof such resistances- has improved con-siderably in the past few years, andthe very violent variations which usedto be experienced, giving rise to crack-ling and other unpleasant effects, arenow to some extent eliminated. Thereis still, however, a tendency for highresistances (except those of the wire -wound type which are necessarily morebulky) to vary from their rated valuewith age.

A New MaterialDr. Loewe has discovered a special

compound which he utilises to coat asmall glass tube. Connections are- madeto the resistance material by means ofsmall pieces of wire wrapped ;roundthe ends, and coated with a bindingmaterial. This end covering is ofcomparatively low resistance, and it isthe space in between the two end con-nections which is covered with thehigh -resistance compound.

The whole is mounted inside a smalltube from which all gas is exhausted,and practical experience shows that aresistance made up in this mannermaintains its value constant undervery severe conditions of load.

A ParallelIt is interesting to note that.

a similar method of constructionto this is actually adopted onthe Ediswan gridleaks and high -resistances which are now avail-able in this country. It willgenerally. be admitted that if re-sistances can be produced in thecompaetness of this type, andstill be constant and quiet inoperation, we have made con-siderable strides in the scienceof resistance manufacture.

INVENTIONS ANDDEVELOPMENTS

SOME NEW RESISTANCESIn this feature, conducted by Mr. Reyner, appear fromtime to time details of some of the latest developments.

The other unit referred to is acompletely enclosed Quartz crystalarrangement. The actual method ofmounting a Quartz crystal is one re -

The new quartz -control unit inpe antedby Dr. Loewe. The elements are con-tained in a bulb of gas at reduced

pressure.quiring considerable care, as otherwiseminor variations in the frequency ofthe arrangement way result. Dr.Loewe, therefore, Isas arranged tomount Quartz crystals in a small en-

closed bulb containing gas at a reducedpressure.

The crystal itself is mounted inbetween the two small plates. If,then, an alternating voltage is appliedacross the plates, at the resonant fre-quency- of the crystal, the latter willvibrate and will set up a luminousglow inside the tube.

A Resonance IndicationThis May obviously be utilised as a

definite indication of resonance, andis particularly useful in tIming a radiotransmitter to an exact wave. Whenthe wave is exactly that of the crystal,this luminous glow will be present, andany deviation from the specified fre-quency will cause the bulb to ,ceaseglowing.

THE " COCKADAY-HARTLEY" RECEIVER

Sne-Mr. John W. Barber's " Cocka-day-Hartlgy " three -valve receiver, de-scribed irT WIRELESS a short time ago,is the best I have yet struck for selec-tivity combined with simplicity of opera-tion. I have varied the actual com-ponents used by Mr. Barber considerably,and yet find that his operating instruc-tions hold good for my own set, oawhich I have already logged a very largenumber of the more distant Continentalstations. The operation of the set upona DX station. is no more difficult thanthat of a " straight " one-valver, and theresults obtained have astonished most ofthe so-called " experts " in this neigh-bourhood.

I should be glad if you could find spaceto publish this letter, in the hope that

it may lead others to constructthis set, and obtain equally fineresults. I do not think enoughresearch has been carried out withregard to producing really good,selective " DX " receivers with-out the necessity of using H.F.amplification. The latter, thoughit undoubtedly is worth while,always introduces more controls.Let us have more of the " D. andnote-mag." .ype.-Yours faith-fully,

ra

The new resistance elements are containedin evacuated glass tubes.

C. M. Deux.E. Dulwich, S.E.22.


A Tuner Unit for the" Flexible Receiving Equipment "

(Continued from page 379)

construction are given, together withthe names of the manufacturers. Anydeparture from the original shouldonly be made with due regard to thesize and shape of the different compo-nent, test difficulty be experienced inassembly.

Material RequiredEbonite panel measuring 8 in. x

6 in. x. 13, in. (Cameo).Baseboard measuring 61in. x 6 in.

in. (Cameo).One variable condenser, .0005 geared

(Ormond).One variable condenser, .0003 geared

(Ormond).One H.F. choke (Beard & Fitch).Two coil holders for baseboard

mounting (Peto-Scott).One 8 -way Clix socket strip (Mag-

num).Two Clix plugs (white and red)

(Autoveyors).Glazite for wiring (L.E.W. Co.).

A rear view of the tuner unit removedfrom the cabinet.

Small length(L.E.W. Co.).

Three in. wood screws (counter-sunk).

of insulated flex

Constructional WorkFirst drill the ebonite panel in

accordance with the details given inthe diagram. This operation is com-pleted with five holes only. Nextsecure the panel to the baseboard bymeans of three countersunk woodscrews. The two variable condensersare then mounted upon the panel' inthe positions indicated in the diagramsrepresenting the front and. back of thepanel.. The only other components tomount are the choke, the two coilholders, and the Clix socket strip.Details of these strips were given in

IV ireless Weekly of the issue men-tioned. They may also be obtainedready-made, as mentioned, in the com-ponent list.

WiringHaving mounted these remaining

components upon the baseboard, thewiring may be proceeded with. Thispart of the work is, as may be seenfrom the diagram, extremely simpleand straightforward. There are twoflexible leads, each of which is equip-ped at one end with a Clix plug (onewhite and one red).

One of these leads is connected tothe moving element of the variablecondenser C, and the other to themoving element of the variable con-denser C,; a third flex lead is alsoprovided, one end of which is providedwith a spade tag for the purpose ofmaking connection to the existing ter-minals of a standard type of X orother tapped plug-in coil. Little moreneed be said relating to the construc-tion of this panel, as the diagramsgiven render the work practically self-explanatory.

The Theoretical CircuitThe theoretical circuit diagram is

given in Fig. 3. The flex leads uponthe panel are indicated as in the otherdiagrams, the Clix plug colours beingspecified in order to facilitate the workof linking up various circuit arrange-ments with the other panels.

The aerial down lead and the earthlead are also equipped with Clix plugs,which connect direct on to the panelby means of the Clix socket strip. Thelead which connects to the tapping ofa plug-in coil is also clearly indicated.In order to connect up the variouspossible tuning arrangements, refer-ence should be made to the otherpanels which have been described.(Some further notes on the use of thispanel, with some circuits to try, willbe given in an early issue.)

NEWS IN ADVERTISEMENTS

Messrs. A. F. Bulgin & Co., in theiradvertisement in this issue, aredescribing various small componentswhich should prove useful for the con-structor who likes to add " gadgets "to a set which is otherwise constructedto a published design.

The Dubilier Condenser Co. aro in-viting inquiries for full particulars oftheir " Dubilicon " competition.

The, Igranic Electric Company, Ltd.,are advertising components suitablefor use in the " Elstree Six " receiverrecently described in Modern Wireless.

f1111111111itIlltIMt1111111-11[111ilifili!P1111111111rniililillirlitifiln

4

4

4

4

This week -endbuild your ownloud speaker!First of all go to yourdealer and satisfy your-self that the "Lissenola,"costing only 13/6, reallyis fully equal in powerand tone to any loudspeaker on the market.Ask your Dealer to puton the best loud speakerhe has in stock-thenuse the same horn onthe "Lissenola" and seeif you can notice anydifference.When you get the " Lissenola "home you can build a hornyourself for a few pence, pro-viding you with a powerfulinstrument which will comparewith any expensive loudspeaker you have ever heard.Or, if you prefer a cone -principle diaphragm-verysimply made-you should geta Lissen Reed as well (1/- extra).If you have never heard a"Lissenola" there's a surprisein store for you.

Before buying ask your< dealer to demonstrate the

< LISSENOLALISSEN LIMITED,18.22, Friars Lane,Richmond, Surrey.Managing Director : T. N. COLE. 1,36

NO. v Nr "or lir \Or 'ROW

1111111111111WHIIIIMIll11111111111!11.1111111111!!1111111111111111111111111

392 WIFtELE'SS. August 7, I92.64

COMPONENTSWE HAVE

TRIEDConducted by the " Wireless " Laboratories, Elstree.

Combined Earthing Switch andLead-in Tube

A, thundenstorms are more frequent atthis time of the year some of ourreaders will be inquiring for some

method of overcoming likely dangers fromlightning, and in this connection we havereceived a combined earthing switch andlead-in tube which is manufactured byMessrs. J. Webb, of 35, Claremont Grove,pidsbury, Manchester, costing 4s. to 5s.,according to the length of the tubesupplied.

The switch is operated from inside thehouse, a diagram showing the necessaryconnections being printed on the cartoncontaining the combined instrument. Thoaccessory is fairly simple to fix, it beingof course necessary to make a hole in thewindow frame to lead into the house.

The component submitted to us was ofthe 12 -in, type, and consists of a lengthof brass rod covered by insulatingmaterial. About a quarter of the waydown the tube is a round flange of metal,by means of which this tube is screwedinto position. One end carries a slatecovering as a means of insulation, andunder this the arrangement for earthing

is provided for, so that whenthe knob is pulled outwards the outsideaerial is connected direct to earth outsideithe house. This is done by means of abrass collar fitting into a brass socket,thus making a direct connection to earth,at the same time short-circuiting the brasswork carrying the aerial terminal to theset. --

The component is well manufacturedand can be strongly recommended.

"Atlas " Variable CondenserMESSRS. H. CLARKE & CO., LTD.,

have sent us one of their " Atlas ".variable condensers for test and

report.This condenser is of low -loss construc-

tion, the fixed plates being insulatedfrom the metal end plates by means ofshort pieces of ebonite, the moving vanes

The Webb lead-in and earthing -switch.

being in electrical connection with themetal end plates, which are cut away inorder to reduce the minimum capacity ofthe condenser. A clearly graduatedmetal dial is provided, which is gradu-ated from 0 to 180 degrees.

Laboratory Tests.-The rated valueof this condenser is .0005 mfd., but whenplaced on test it was actually found to

be .0006 mfd. The H.F. resistance wasof a low order, while the insulationresistance was found to be infinity.

Terminals are provided for makingconnection to the instrument, which is ofthe one -hole fixing type. It is stronglyconstructed and with a degree of effici-ency well up to standard.

Cantophone TunerMESSRS. THE CANTOPHONE

WIRELESS CO. have sent us fortest and report one of their tuners.

The design of this instrument is novelin .that the tuner unit comprises a re-action control in each case, the wholebeing interchangeable so as to cover

4-4-4-4----------------+-4-4r

The Cantophone Tuner No. 2 has atuning range of 220 to 780 metres

approximately.

various ranges. Three ranges are sup-plied, which cover the wavelength bandsbetween 70 and 2,000 metres, the oneactually submitted for test being No. 2,which covers 220 to 780 metres. Fur-ther, a direct calibration scale is providedfor use with a particular make of vari-able condenser. If a different make isused, of course, the calibration does notquite hold, although it is fairly approxi-mate.

Test Results.-When placed on test inthe aerial circuit it was found that thetuning range of this component was ap-proximately him 220 to 750 metres,while the reaction control was found tobe perfectly smooth when correct valuesof H.T. and L.T. were employed. Thesignal strength from distant stations wasfound to be normal, while a satisfactorydegree of selectivity was obtained inview of the fact that no stage of H.F.was employed.

The instrument Jis well finished androbustly constructed. It is intended formounting behind the .panel, and it isonly necessary to drill one hole for thereaction control. Connections are madeto the tuner portion of the instrument bymeans of soldering tags, while two flex-ible leads finished with metal eyelets areprovided for the connections to the re-action coil. This instrument can berecommended for use.

Accumulator ReviverMR. SKADDER has submitted to us

for test at our Elstree Laboratoriesa sample of a liquid for reviving

accumulators which have sulphatedthrough overloading or other causes.

Manufacturer's Claims.-Two distinct

The " Atlas " variable condenser isconstructed on low -loss lines.

claims are made for the fluid submitted:(1) That it will revive spoilt accumula-tors so long as the plates are not badlybuckled or shorted, and (2) that it willalso serve partly to charge an accumu-lator in the sense that the charging cur-rent need be passed for a much shortertime if the liquid has been used in con-junction with complete replacement ofthe ordinary acid.

The liquid submitted was transparentand evidently contained acid, but gaveno other indication of its nature.

Laboratory Tests.-Two old 2 -voltaccumulators of 105 ampere -hour capac-ity were selected which through con-siderable overload on a motor starter hadsulphated badly. Their condition wassuch that they would gas freely afterhalf -an -hour's charge, and would give acurrent for about an equal period beforebecoming completely discharged. Afterthe addition of the liquid under test thevoltage of these accumulators rose fromalmost zero to 0.8 volts and 1.4 voltsrespectively. After charging for 20minutes at 6 amps. the voltage rose to2.1 and 2.2 volts respectively.

On discharge at 6 amps. both accumu-lators went down in 20 minutes, so thatthere appeared to be no improvementbrought about by the electrolyte.

Both accumulators were then chargedat 4 amps. for 7 hours. At the end ofthat time they were discharged at therate of 3.8 amps. One accumulator wasfound to last si hours and the other 6ihours.

Both accumulators were then given afull charge, and were found to behave as,_if fully restored. The reduction of thesulphating was also very evident.

General Remarks.-Although the testswe have made do not indicate that theliquid gives a partial charge as claimed, -yet it would appear to be very useful asa restorative for accumulators whichhave been given up as hopeless.


OW often some amateurfriend comes to askone's advice on acertain point wheretwo different arrange-ments are possible,asking which of them

is best-. And in perhaps nine casesout of ten one cannot say definitely,much to. his disappointment.

It is strange, however, that so manythings occur in wireless that either goagainst accepted practice or are deadagainst the (possibly incomplete)theoretical view. With some H.F.circuits where H.F. transformers areused it will be found necessary toemploy connections other than thosegiven by the makers, to take just oneexample.

A "Back -lash " ExampleI have always found that when a

receiver inclines towards back -lash asregards the control of reaction it isnecessary to increase the value of thegrid leak. This is a point I have ex-periencd again and again withvarious types of valve, yet it has beenshown theoretically that in most casesthe reverse should be the case, andthere are no doubt many experimenterswho will say that this is correct.

Another point that has beenemphasised from time to time is thatback -lash may be cured by reducingthe H.T. and L.T. voltage applied tothe valve. Yet this is not a hard andfast rule. I have found that with

WHICH ISBEST ?

MI Mill Mil

certain types of valve if the filamentis run at too low a temperature back-lash will result, and in some cases,

... ''''

Mr. Lloyd George at the ChristianEndeavour Convention at the CrystalPalace. The" Public Address" micro-phone may be seen in front of him.

too, I have experienced back -lash whenthe H.T. voltage applied was too.small.

111 1111111111

Another CaseWith regard to back -lash, again, 1

have invariably found, up to quiterecently, that a receiver which wasperfectly delightful as regards re-action control would develop thisannoying symptom when the grid leakwas taken to. L.T. - instead ofL.T. as is the usual practice. Iconstructed a Reinartz receiverrecently, however, that suffered froman extraordinarily bad case of thiscomplaint, and nothing could be doneto cure it except connecting the gridleak ter L.T. -.. Incidentally, thisgave better signal strength, though ithas been shown time and again thatthe positive connection is the best !

Shortly after this set was built thecoil, tuning condensers and H.F. chokewere changed, but when re -assembledback -lash was still found to resultwhen the grid return went to L.T. .

What then was the cause of thiscurious behaviour on the part of thisreceiver ?

Be Wary !It is cases like these that impress on

the amateur even of ten or twelveyears' experience the difficulty ofgiving hard and fast rules on manypoints regarding the practical applica-tion of laws that have been laid downtheoretically, and in particular iturges him to caution when asked togive advice on certain phenomena thathave been observed under circum-stances of which ho is unaware.

No. 42. Appreciation !

JUST THROWe)001. AT

-cNos!!egs

3'?4, WIREL SS., August 7, 1926,

THE

H.T. TAPPING MYTH.IITIMMese[atl...V,-^"1,4

al gin Ai te,

By G. P. KENDALL, B.Sc. Assistant Editor

Do we really need all those tapping points? Mr. Kendall's views take Vie form of an emphatic negative.

Or

irr*-31 f

NCE upon a time wehad, for our sins, touse valves which some-times worked reallymarvellously, as itseemed then, whentactfully treated, and

at other times sulked obstinately and.refused to respond to any amount ofcoaxing on the part of the distractedoperator. There was, of course, verylittle uniformity among the differentvalves of the same alleged type, butmany of them required a very exactadjustment of filament current beforethey would begin to thinkabout working properly.There was even one remark-able contrivance in which itWas possible to adjust thevacuum to the desired degreeby holding a lighted matchto a little projection forMedin the valve and containinga special sUbstance!

Endless Fiddling- Critical adjustments werethe order of the day, or atleast so it seemed, although alack of understanding on thepart of the operator of 'thesenew appliances may haVe hadsomething to do with it.Now, one of the adjustmentsWith which we used to fiddlemost painstakingly was thatof the plate, voltage, for it seemed thatoften only a few volts alteration wouldmake all the difference'in the world tothe results.

A Diverting PastimeMany of the high-tension batteries

which I used at that time consisted oflarge banks of single separate dry cellsof considerable size, so that it was pos-sible to tap in at every 1z volts, andone used to spend much time chasingup and down amongst the cells, seekingfor the exact voltage which seemed togive the best results.

A LegacyI believe it is a legacy from those

early days that we now suffer from

what I call the " H.T. tapping myth."Practically emery high-tension batteryturned out has tappings every three orsix volts, or at some similar smallintervals, . and most beginners spendmuch good time conscientiously stick-ing the plugs first in one hole and thenin another, observing at the end of itall that there is exceedingly littledifference in results at any positionwithin quite wide limits.

The Usual ExperienceThe high -frequency valves seem to

work better with the higher voltages

bit critical as to high-tension voltage,the only need for any adjustment atall being usually in the case of a detec-tor valve with reaction, the aim beingto secure a smooth adjustment of theoscillation control. As a rule, how-ever, the arbitrary choice of a ratherlow value, such as 36 or 45 volts, willgenerally produce the desired result atonce. These things being so, one istempted to ask, " In the nameof common sense, why all thosetappings? "

The author urges that about five tappings arecappli-for general purposes.

up to about 72 or perhaps 80 or 90 inthe newer neutralised circuits, the low -frequency valves seem to want all theycan get, although there is little im-provement with most of the moderntypes above about 100 volts, while thedetector seems perfectly happy with45 volts; increases above 45 do notappear . to improve signals, and maymake reaction floppy. These, broadlyspeaking, are the usual experiences ofa beginner, the exact voltages depend-ing, of course, upon the particularvalves which he is using; but there isas a rule no very great variation fromthose which I have given.

General RulesThe fact is that modern valves in

the vast majority of circuits are not a

Why Not ?Why not drop the use of

H.T. batteries simply spottedwith tapping points, and useunits of reasonable size, say,120 volts, with the tappingpoints at the voltages whichwe really use, rather than themultitude of ones which wenever use? What we want isa tapping at 36 volts and at45 volts for the detectorvalve, others at 72 and per-haps 84 volts for the H.F.valves, and a terminal at theend of the battery for thelow -frequency valves.

Do You Agree ?These views, of course, are

decidedly personal ones, anddare say quite a number ofreaders will disagree with me,

in which case I hope they will nothesitate to express their views !

0 0Wireless Licence Regulations

tinder the G.P.O. regulations, whichare of a surprisingly flexible character,you are allowed to take away yourwireless set with you when you go onholiday. The licence clause whichstates that the apparatus is to be usedonly at a fixed address means, weunderstand from a G.P.O. official,simply that it must not be stretchedto cover two permanent addresses ortwo permanent sets. The set forwhich the licence has been taken outmay be moved occasionally, providedthat it is not used for an unreasonablylong period at the second address.

Aaiust 7, 1926, WiREtgSS.

A Reinartz Tuned -Anode Set(Continued from page 367)

Valves should be inserted in theholders temporarily in order to ensurethat ample clearance is provided, andthe panel should be placed in its cor-rect position to ensure that none ofthe panel components foul those en thebaseboard.

WiringThe baseboard components may then

be fixed in their positions, the panelplaced finally in position and screwedhome, when the set is ready forwiring. No difficulty will be experi-enced here, most of the wiring beingat the back of the baseboard. Careshould be taken that the connectionsto the screened coil are correct, andalSo that the jacks are correctly wiredtsp.

When the receiver has been wired itis ready for test. For this purposethe Reinartz coil' must be obtained for

provided that it is reasonably similar,but the particular coil quoted matchesthe inductance of the screened coilapproximately so that the dial read-ings on the first two condensers arcsimilar.

Now, without connecting the aerialup, test the. reaction. Switch on the,valves and place the potentiometertowards the positive side. This is toensure that the first valve shall notoscillate. Now, on increasing thevalue of the reaction condenser (thirdcondenser on panel), the second valvemay be caused to oscillate: This willbe observed -by a click in the 'phonesor loud -speaker, and the value of- theH.T. and filament brilliancy should beadjusted until this click is quite softin character and there is no backlashon the adjustment. That is to say, thereaction starts and stops practicallyat the same point on the condenser,

18"Cl,

/

Fig. 4.- All necessary drilling centres canfront of panel layout.

insertion in the screen. This may bepurchased ready-made with the screen-ing case, or may be wound up by theconstructor himself.

The winding is simple. The maincoil consists of 80 turns of 28 d.s.e.wire wound on a 2 -in. former. Thiswinding is then continued for afurther 30 turns, tappings being takenat 15, 20, 25 and 30 turns.

The connections to the coil are asfollows: Main coil beginning to No. 1,end to No. 2. Tappings to Nos. 3, 4,5 and 6 respectively, No. 6 being the30th turn.

The diagram in Fig. 3 gives the con-nection between the sockets of thescreen and the terminals thereon, andalso the numbers of the pins on thetoil itself, looking from the bottom.

Testing OutHaving tested the connections in the

-usual manner to ensure that there aretoo faults, the receiver may be testedon signals.

Plug a No. 60 X -coil in the firstsocket. A different value of coil, i.e.,a 50 or 75, may be used if desired,

be obtained from this

and slides into oscillation withoutplopping.

Aerial TestsThe aerial may now be connected

up and the set tuned in to the localstation. When this has been done thepotentiometer may be moved towardsthe negative side a little at a time.As this isdone it will be found thatthe signal strength will increase, andthat at one particular point a verymarked increase in strength will ocr-ar.

If the potentiometer is moved toofar towards the negative side, the firstvalve will burst into oscillation. ThisMust not he permitted, because suchoscillation will cause interference tothe neighbours. It is not necessary,however, to move the potentiometer sofar, a sensitive point being obtainablebefore the oscillation point is reached.It is advisable to keep the reactioncondenser at zero during this portionof the adjustment. It may subse-quently be increased, when the signalstrength will be considerably improved.

This completes the adjustments, and(Concluded on next page.)

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increase income required where we are notfully represented. Applicants must havepractical knowledge of installation of Set andAerial, be a householder or live with parents,and be able to give references ; state age andexperience. Address : Dept. 38, GENERALRADIO COMPANY, LIMITED, Radio House,Regent Street, London, W.I.

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WET H.T. BATTERIESBritish made round or square Leclanche Gloom Jars,

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2 VALVE AMPLIFIER, 35/1 -Valve Amplifier, 20/-, as new; Valves, DE. .00,

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COUPON.QUESTIONS & ANSWERS.

This coupon must be accompaniedby a P.O. for 2/6 for each questionand a stamped addressed envelopewhen sending queries to the RadioPress Information Dept. for a

postal reply." WIRELESS." Vol IV. No. 11.

All communications regardingadvertisements should beaddressed to :

The Advertisement Manager,"WIRELESS,"

Bush House, Strand, London, W.C.2Telephony: City 9911.


A REINARTZ-TUNEDANODE SET

(Concluded from page 395)

tuning in may now be carried out inthe normal manner. The setting ofthe potentiometer will not require tobe altered much, and need Rot betouched in normal operation, alltuning being carried out on the twomain condensers with the assistance ofthe reaction control. The sensitivepoint on the first valve will be foundto be slightly different for loud andsoft signals, but the variation is only

ValvesThe first valve should be of the high -

impedance ty pe usually quoted as suit-able for HE, work. The second valvemay be any suitable detector, of suit-able voltage for the accumulatoremployed. The third valve is the firstin the L.F. chain, and should be a low -impedance valve. An ordinary L.F.valve may be employed or a small -power valve. The last valve shouldbe a power valve capable of handlingthe volume required.

Selectivity: The selectivity is controlled to some

extent by the tapping on -the screened -coil. The smaller this is made, thegreater the selectivity, but the signal

strength also falls off somewhatrapidly. A position for best results iseasily obtained by trial and error,after which the tapping need not bealtered. (Further notes next week.)

BEING FUNNY BYWIRELESS

(Continued from page 368)

world to conquer. Every true artistis unsatisfied so long as there is stillany victory to achieve, and hereradio offers us untold chances. Everytrue artist has at some time or anotherlonged to be able to give his art to thelittle country places, to the inhabitantsof those lonely- parts where it is im-possible to tot-IT-in fact, to share whatgifts he or she has universally. Broad-casting has made that into a realityfrom a dream.

A Great AmbitionDo not think I underestimate any

friends of the theatres. You shouldknow how I value them, for they aremy oldest friends. But there are hos-pitals where, perhaps, a song such as" Expectin' a Leddy ! " and therest might while away an hour withcare and pain forgotten. There arework -tired folks the country throughwho Harry Lauder longs to coax intomerriness and content wi' his fooling.Every wireless comedian wants to make

care -weary folk laugh an' increase" goodwill amang men."

An International LinkAgain, it is universally recognised

that nations become more friendly themore they learn about one another,as is the case between English-speak-ing nations. Wireless, and radio -humour in particular, is going to be abig influence for international friend-ships among the peoples, for who canbe at enmity with a real laughter -maker? Every comedian's biggestambition is to make real friends with.his audiences. I like to think I'm realfriends with all mine in the theatres,and now wireless has given us thebiggest chance we've ever had yet-nothing less than that of being friendsWith all the world.' An' what can manwant more?

A Simple TestI have a good loud -speaker giving great

volume without distortion, but amafraid I might demagnetise it owing tothe terminals on it not being marked.The simplest method to adopt to

determine the correct polarity is toconnect the loud -speaker in circuitand to so adjust it that it just rattlesslightly on strong signals. When soadjusted reverse the leads to it, andif the rattle ceases it was originallyconnected correctly. If, however, therattle is accentuated the first connec-tion was not the correct

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If you are unable to obtain your favouriteWireless Journals from your Newsagent

or Bookseller send a subscription.

WIRELESS INCORPORATING Twelve months - 13/-WIRELESS WEEKLY Lesser periods, pro rata

MODERN WIRELESS Twelve months - 15/ -Lesser periods, pro rata

THE WIRELESS CONSTRUCTORTwelve months, 816 Lesser periods, pro rata.

Promptly delivered through the Post.

RADIO PRESS, LTD., Bush House, Strand, London, W.C.2

August 7, 1926,

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Helps you to stockfor public demand

"WHAT the Wireless Journals are Doing "-a prominent

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Shelves need no longer be loaded with obsolete goods. This article givesadvance information regarding components to be used in forthcoming issues ofpublic wireless journals, and the public demand can now be both closely followedand approximated.

THE WIRELESS DEALER always contains something interesting andinformative. It keeps you in close and intimate touch with the personnel of theIndustry and with all developments and inventions. Send for a specimen copy now.

SELECTION FROM CONTENTSSpeed up the High -Power Stations!"The Wireless Dealer" Service and Testing Uni

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Plain Words on Trade ConditionsBy Leon A. Sharland

New Components for the Coming SeasonBy J. H. Refiner, B.Sc. (Hons.). A.C.G.L.

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Iv WIRELESS. August 7, 1936,

All Valveshave constructional featuresbut only P.M. Valves have the

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Which valve con-struction gives youthe most for your

money

For 4-vott accumulator or3 dry cells

THE P.M.3. (General Purpose)0'1 amp. 16/6

THEP.M.4 (Power) 0'1 amp. 22/6

For 6 -volt accumulator 4/4 dry cells

THE P.M.5 (General Purpose)0'1 amp. 22/6

THE P.M.6(Power)0*1 amp. 22/6

For 2 -volt accumulatorTHE P.M.1 H.F. 0'1 amp. 15/6THE P.M.1L.F. 0'1 amp. 15/6THE P.M.2 (Power)0'15 amp. 18/6Thus prtees,to net apply tn Irish FretStatai

ADVT.. THE MULLARD WIRELESS

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Oldo7ypeCylindricalConstruction

OrdinaryLoop

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Look at the length, thickness and design of theMullard P.M. Filament and you will appreciate whythose who understand valves place its results 33%higher than any other on the market.This wonderful P.M. Filament

Is supported by 5 strong but resilient hooks.Cannot be broken except by the very roughest

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ASK YOUR RADIO DEALER FOR THEVALVES WITH THE P.M. FILAMENT.

MullardTHE MASTER. - VALVE

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Publislod by RADIO PRESS, LTD., Bush House, Strand, London. W.C.2, on Tuesday of each week, and printed for them by THE AVENUE PRESS(L. Upcott Gill & Son, Ltd.), 55-57, Drury Lane, W.C.2. Address for Subscriptions and Editorial Communications :-Bush House, Strand, London,W.C.2. Address for Advertisements :-Advertisement Manager, AN IRELESS, Bush House, Strand, London. W.C.2. Registered as a newspaper and fortransmission by Canadian Magazine Post. Subscription rates :-13s. per annum, 6s. 6d. for six months, post free. Sole Agents for Australasia :-GORDON & GOTCH (Australasia), LTD. For Canada :-IMPERIAL News, LTD. For South Africa :-CENTRAL News AGENCY, LTD.

incorporating wireless weekl

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