No. 10 DECEMBER, 1937

Pages 5 and 6 give fullinformation concerningthecon- struction of a unique one -valve transmitter, illustrated above. N1 AC THE SCIENTIFIC VALVE

"rmossomrvionoismir soimmimmr British NOWIIw Made THE SIGN OF A GOOD VALVE

VP 215 Variable -Mu H.F. Pentode. AC HL Medium Impedance Triode. D 210 Non-Microphonic Detector. AC Y Hivac-Harries Medium Slope Y 220 Hivac-Harries Medium Tetrode. Power Tetrode. AC /Z Hivac-Harries SteepSlope PX 41 Three -watt Output Triode. Tetrode. MIDGETSA rangeofHivac 2 -volt AC/Q Hivac-Harries Beam Power "Midgets." Tetrode.

A SPECIAL RANGE OF 2 VOLT SHORT-WAVE VALVES Non-Microphonic Detector.High Gain Screen Grid.Super Power. Class B. ALL THESE VALVES DESERVE YOUR SPECIAL ATTENTION There are over 50 types of HIVAC valves.2 -volt Battery types. 4 -volt A.C. Mains valves (indirectly heated). 4 -volt A.C. Mains (directly heated).13 -volt Universal A.C./D.C. valves (indirectly heated).2 -volt "Midget" Battery valves and 2 -volt Short -Wave Battery valves.Full details will be sent FREEtoallaskingforLIST,andChart"S.M." British Made by HIGH VACUUM VALVE CO., LTD., 111-117, FARRINGDON ROAD, LONDON, E.C.1. TERminus 2587 VORTEX ION 15watthighgain,highqualityamplifier within 3DB 30-17,000 cycles. Outputs in stock for 4, 7.5 and 15 ohm speakers or to any impedance to order. .04 volt input required, separate mike and 'gram inputs with mixing faders. PRICE 84- gns. Gauze case,12/6 extra. Microphones, Piezo pick-ups, G.12 Rolas and Collaro motors. Trade supplied. VORTEXIONLTD., 182 THE BROADWAY, WIMBLEDON, S.W.19.

Telephone : Liberty 2814. ELECTRADIX BARGAINS TRANSMITEERS. MORSE DX! AND SIGNAL KEYS, Royal Air Force model, balanced Every Short Wave Fan should join the B.S.W.L.-the action,solidbrassbar, leading British organisation for the DX enthusiast. We tungsil contacts, indicator Produce our own" Review- : run our own QSL Distribut- tamp. Type KBSI a guinea ing Bureau issue " Heard all Continents" Ceri ideates and keyfor7/6. Other keys can honestly boast of running one of the friendliest DX from 4/6 to 30/-. Learner's societies in the Wo ld,There are many adv,.ntages outfit complete, 4/9. Ask joining such a society. For further particulars wri'e to :- A Guinea7/6 for special illustrated Key The Secretary. British Short Wave League, Ridgewell, Key for fist" S.W." H t stead, Essex, a copy of our publication HEADPHONES. Light weight. 2,000 ohms, 4/6. Single Wave Review" through your newsagent- price 6d. This high res. earpieces, 2/6. Sullivan 120 ohm W.D. model. magazine is also the official organ of the British Section Aluminium body and headbands. Maker's price to -day. of the World Friendship S..ciety of Radio Amateurs. I51-.Our price 2/9 per pair.3d.postage. " DX FOR DXers BY DXers " ELECTRADIX RADIOS 218, Upper Thames Street,London,E.C.4. felePhane :Central 4611 CLASSIFIED ADVERTISEMENTS are charged at 2d. perword, minimum 2s.All advertisements must beprepaid. Cheques and postal orders should be made payable to "The Short -Wave Magazine." WE BUY FOR CASH Short -Wave Parts, Sets, TestAMERICAN ALL -WAVE DOUBLET AERIALS. Meters,etc. Bringorsend. - UNIVERSITY complete with Variable Transformer, 15s.Also all RADIO, LTD.,82,Hampstead Road,Euston. types of American Valves at low prices. -C. .T. N.W.1. SCATES, 5, Church Street, N.W.B. REPAIRS AND RE -ALIGNMENT by theold - CONDENSERS. --FixedPaper.In Metal Con- established City Repair Service.Radio repairs only. tainers.1,000 volt. Wkg. 8 mfd. 10s. 6d.; 4 mfd. All -Wave and Standard Sets and Amplifiers "hotted 7s. 6d.; 2 mfd. 4s. 9d.; 1 mfd. 2s. 6d. TUBULARS up,". rebuilt,repaired,etc.Estimatesfree. DISTAVOX SERVICE CO.,119,BtinhillRow, in Bakelite cases, 1,000 volt. Wkg. 1 mfd. 2s. 6d.: E.C.1.National 8589. 0.5 mfd. 2s.; 0.25 mid. ls. 9d.; 0.1 mfd. ls. 3d.; HERE'S YOUR CHANCE TO SAVE MONEY. "ENGINEER'S GUIDE TO SUCCESS"shows now The following new and unused radio snips offered by to qualify in Television, Sound Recording, Radio G5KA :Two TAYLOR T50's,35s.each.M.R. Engineering and Servicing, Wireless Communica- Reisz type mike, with ring stand (all chromium) and tions, etc., by studying at home with The T.I.G.B. inputtransformer,32s.6d. Raytheon RK23, Write to -day for this Great Guide -FREE -which 17s.6d..5 -meter trans -receiver (two tube), pro- contains the world's widest choice of engineering fessional built; fitted in magnificent cabinet holding courses -and alonegivestheRegulationsfor batteries, fones, etc.; complete with latest pattern QualificationssuchasA.M.I.E.E.,A.M.I.R.E., hand -mike combination and vertical rod antenna; A.M.I.T.E., this cost well over £15 -best offer takes.3 -tube, A.M.I.W.T.,C.and G.,etc.The 5 -meter receiver (superregen); Eddystone compo- T.I.G.B.GuaranEoesTrainingurtilSuccessful. nents throughout ; a terrific bargain at £4.-G5KA, -THE TECHNOLOGICALINSTITUTE OF 41,Kinfauns Road, Goodmayes,Ilford,Essex. GREAT BRITAIN, 105, Temple Bar House, Lon- Phone: SevenKings 2888. don, E.C.4.(Founded 1917.20,000 Sum -teases).

1 vi --35Mullard TRANSMITTING PENTODES LIFTER for AMATEUR RADIO The PVO5-15 and PVI-35are fully screened pentodes with indirectly heated cathodes. They set a new standard of operating efficiency on shoit wavelengths. For technical data, send a postcard to- TRANSMITTING DIVISION The Mullard Wireless Service Co. Ltd. 225 TOTTENHAM COURT ROAD 60 -120 -80 -40 LONDON, W.1 TESTING Negd Trade 1a' h. INSTIFEIUMENTS

Universal AVOMINOR The 46 -rangeUniversal Compact multi -range AVOMETER A.C./ D.C. meter, 22 Model 7 ranges.Providesfor World'sforemost multi - A.C. and D.C. voltage range meter. Has 46 ranges. measurements up to 500 Provides for all A.C. and D.C. volts ;Current voltage and current measure- measurements up ments; Resistance measure- to 500 milliamps; ments; Capacity tests; audio - frequency power output Resistancemeas- measurements; and Decibel urements from tests. No external shunts or 0-10 megohms. seriesresistances.B.S.1st Highlyaccurate. gradeaccuracy.Protected Total resistance by automatic cut-out against 600,000 ohms. damage throughover -load. Completewith 16 Gns. leads,testing prods, crocodile Resistance Range Extension clips, and instruc- Unit (for measurements clown tion hook' -t. to 1/100th ohm). 101- Price £5 10 0Leather Case 101 - .36 -range Universal Avometer, 13 gns. Also, the 13 -range D.C. 22 -range D.C. Avometer. 9 gns. AvoMinor,45, - Leather Carrying Cases, Write for list of "AVO" Instruments THE AUTOMATIC COIL WINDER & ELECTRICAL EQUIPMENT CO.,LTD. WINDER HOUSE, DOUGLAS STREET, LONDON, S.W.I Telephone :Victoria 3404/7. THE SHORT-WAVE MAGAZINE

Vol. I DECEMBER 1937 No. 10

Editor BASIL WARDMAN Editorial Asst.: S.W. CLARK I 2AMW Advertisement Manage, C. T. MILDENHALL

AGREAT DEAL has been said and written about the they would enrich themselves,satisfyi he public, home constructor.Well-known authorities have in- and keep our money at home. formed the world at large that home construction Short-wave construction iseternally new.It is is dead, killed by mass produced receivers. a creative hobby conquering time and distance, not We humble remnants of this extinct race shouldto be stifled by pessimists.If our own people not presume to dispute the statements of the wiseignore our wants, we must turn to those who will men, but somehow our correspondence, our contactsatisfy them. with dealers and radio clubs, seems to indicate a The amateur motor mechanic was once treated in large interest in home construction, particularly inthe same manner.It was thought that mass pro- short-wave apparatus. duced cars would eliminate him.He still tinkers Deep in the ditch of mass produced broadcast setsin his garage, his semi -technical knowledge is a vital it is probably impossible to see the vast fields of factor in the "new car a year" market. short-wave home construction "over the top." From The idea of regarding a car as a sealed mystery a distance they are clearlyvisible ;from three to be left severely alone has long been abandoned. KILLING THE GOOSE thousand miles away our American cousins have The owner is treated as an intelligent being, able to espied these fair pastures, and every month sell usappreciate the minor technicalities of his vehicle, many thousandsof pounds worth of short-wave encouraged to do his own repairs, to tinker in his garage, and the success of the motor industry proves components and receivers.Hit by the slump they . realised the necessity of creating a demand for their the logic of, this policy. products,ofnursingsmallmarketsuntilthey The 6,000,000 radio users in this country are not became remunerative.They studied the needs of, fools, and are tired of being treated as such.The insteadofdespising,the short-wave "fan" and "hush-hush" policy of keeping a wireless set a secret "ham," and now they are reaping their reward. box of tricks is played out.The semi -technical man What a pity so many of our manufacturers per- does not like mysteries, he likes to tinker as does his sist in remaining at the bottom of the ditch.If car -owning brother. insteadofsittingthere,screamingfortariffs The home construction market can be developed (although they declare there is no market), they to greater peaks than it. has ever touched.Let us would climb out, foster and cater for the demand, hope our own people will do it.

Contributions for publication in our editorial pages will be givenconsideration and payment willbe made formatter used. Only manuscript accompanied by a stamped, addressed envelope will be returned.Whilstwe are willing to advise on suggested articles no guarantee of acceptance can begiven. The publisher does not necessarily agree with the views expressed by all correspondents and contributors, the aim being to open the columns to every phase of opinion. Annual subscription-Inland, 8s.; Abroad, 10s. Post paid.Published on the first Wednesday of each month at 84/86 Tabernacle Street, London, E.C.2.'Phone :Clerkenwell 6230.

3 HAVE YOU HEARD...? An abstract of the past month'sconditions, as compiled and presented by F. A. BEANE (2CUB)

YES! HAVE YOU BEARD? And what can't we hear? that reminds me of a veri from SRI, Poland, which Everything is at our finger-tips, whether war riddenwas sent to "Essex, U.S.A. !" Spain, maritial Japan, romantic Cuba, diminutive Dominicana, jazz dissipating America, coffee produc- News from Latin America ing Colombia, its rival claimant to world supremacy . Much of interest is now available in the evenings ; Guatemala, or sunny Australia ; we control all ! And generally, when good conditions prevail, I find the the winter has increased our scope, for no longerNorth Americans monopolising the 31 m. band from is it necessary to sit up half the night to hear the about 21.00, shortly after, or sometimes even much fascinating Latin Americans or to ensure wonderful earlier, follow the Cubans, then the Dominicans from reception from North America. about 22.30 and the HJ's and YV's from 23.30 or Just before writing this I took a spin at the dial so.There is nothing really new to report from the before partaking of a final meal and bed, and to my "Pearl of the Antilles" except that a new station, amazement I found W8XK (48.86 m.), Pittsburgh, employing the call -sign COCU, will shortly appear the popular broadcaster, romping in long before on 45.52 m., 6,590 kcs., and will relay CMCU, "de 22.00, a truly astounding signal.VP3MR (49.42 Garcia Serra," with 400 watts power.The schedule m.), of Georgetown, was quite good at 21.45 just is to be 12.00-05.00 on weekdays and 12.00-24.00 on as we used to hear it when it made its etheric debut Sundays, and the address, to which reports should in the 40 -metre amateur band some time ago.The be sent, is "Estrada Palma No. 25, Vibora, Havana, Cubans COCH, COBC, COCQ, COCM and COBXCuba." were brilliant long before midnight, while at 23.24 The Dominican Republic furnishes a newcomer in I was surprised to find OKG on a new wavelength of HIlL of Santiago de los Caballeros, operating in the 33.7 m.At 24.00 they obliged with an English region of 46.2 in.; that is very slightly higher in announcement "Short -Wave Station COKG in San- wavelength than the popular and powerful YV4RB tiago, Cuba, P.O. Box 137," and followed with of Valencia.I have heard it quite well from 22.30 announcements in Spanish, given by a lady an- or so, and the station call is given clearly in Spanish nouncer and interruptedfrequently by chimes, and English at the hour, i.e., at 22.40, 23.40, 00.40 sometimes one or three, but generally two.Yes G.M.T., and so on, as Dominican time is 4 hours 40 winter conditions are here again, and so be prepared minutes behind G.M.T. 4 chimes precede the identi- for dx and many new Cubans-and Dominicans ! fication announcement,thelatterbeing usually "MIL, Emisora Nacional el Diario, Santiago de los News from the .East Caballeros, Republica Dorninicana" followed by the Japan has made changes in view of these condi- English call "Short -Wave station HIlL at Santiago tions and so their transmissions for Europe are now City,Dominican Republic,West Indies."Inci- carried by JZI and JZK, on 31.46 and 25.42 metres dentally these announcements are often given at respectively, between 20.00 and 21.00.Siam, too, fifteen -minute intervals,thatisat22.40,22.55, has made alterations with the result that HS8PJ is 23.10, 23.25 G.M.T. and so on. now heard on 31.54 m. each Thursday from 13.00 On a slightly higher wavelength of about 46.27 m. until close down at 15.00, but whether this is a wise willbe found yet another ofthesefascinating move or not I cannot say since the band is already"mushroom" transmitters; this time HI4V, of San overcrowded, particularly at night. Francisco de Macoris (very good for refreshing one's I have often been asked whether KZRM will geographical knowledge!) and this has been heard verify; my answer is in the affirmative for I have at good strength from midnight until close down at their QSL card before me.Lucky? Oh, no, it isn't02.00, or 9.20 p.m. Dominican Time.Unlike its mine I regret to say; it belongs to H.T. (Bridgend), compatriot HIlL, however, it does not appear to and is particularly interesting.The card itself is make use of English, at least it did not during the buff and bears large call -letters and the title "Radio two hours in which I listened to its almost incessant Manila," also the following details :-power 1 kw.; rumbas, boleros and tipica music, characteristic of wavelength 31.35m., 9,570 kcs. or 25.33in., all Latin-American broadcasters, hut despite this, 11,850kcs.;scheduleMonday -Fridayinclusive identification is a matter of the utmost simplicity as 10.00-14.00and21.30-23.00G.M.T.;Saturdays a four -chime signal, with the last note hardly dis- 10.00-15.00 and 21.30-23.00; Sundays 09.00-15.00 cernible,is used at each hour-don't forget the G.M.T.Broadcasts are carried out simultaneously difference in Dominican time-together with the on "long" and short waves, in English, Spanish andannouncement in Spanish "Broadcasting 8I4V, La Filipinodialects"fromfourstudiosatopthe Voz de la Marina, en San Francisco de Macoris, Insular Life Building,'the owners being Erlangercapital de Provincia Duarte, Republica Domini- and Galinger, Inc.Actually KZRM is heard near eana."At other times the call is given briefly as 31.33 in. and not on exactly 31.35 in.Incidentally "Emisora HI4V." While on the subject I should H.T.'s reception was in July whereas mine occurred like to mention HISN, a low -powered broadcaster on in September and so I expect I shall have to wait48.8 in.This, too,is well heard over here from a little longer before I receive a card !And I hopeabout 23.00 and favours us with English announce- that they don't address mine to "England, Austra- ments.4 chimes herald the announcement "Short- lia"-T.T.'s is addressed, "Wales, Australia!" AndWave station HI5N,inMoca City,Dominican

4 Republic" ;a similar number of chimes intersperse shall send mine to "Radiodifusora CXA8, Monte- the following announcements and advertisements,video, Uruguay" and then hope for the best I while the call is repeated in Spanish several times and the station styled "La Voz de Moca."Broad- Spanishvociferations casts are concluded at 00.40, or a few minutes later, The Spanish war stations, although causing chaos with the call, "Buenos Noches" and the National inthe already too over -crowded 40 m. amateur Anthem. HI5N was well heard here just two yearsband, still hold a certain amount of interest for the ago, but was then in Santiago de los Caballeros and listener, and, as I write this, I am listening to sta- known as "La Voz del Almacen," while their verifi- tion EA1DD, the operator of which made an appeal cation, which I was fortunate enough to secure atto -members of the B.S.W.L. for "control cards." that time, is particularly attractive.I know that This station is operated by the 26th Division, on many dx'ers are often in a quandary as to wherethe Aragon Front, and generally announces itself to address reports to new stations, but I can assure thus :"Hallo, here is station EA1DD of the 26th them thatlettersaddressed thus(for example) Division of the Spanish Republican Army, operating "Radioemisora HI5N, La Voz de Moca, Ciudadin the Aragon Front, at the service of the Spanish Moca, Dominican Republic," invariably reach their Popular Front Government," the wavelength being, destination without much bother on the part of theaccording to the operators, 40.5 m.In reply to postal authorities ! "control cards" they send a letter and also answer, or acknowledge reports during the course of their Canadianverification English broadcasts,which take place-war con- ditions permitting !-from 21.30-21.45 and 00.30- Lastinon,thIinadvertently stated,or rather 00.45.Other interesting stations are the Govern- suggested that the newcomer on 49.9 m. was CJCG, ment "Radio Norte," Madrid, on approximately 42 whereas it is, of course, CJCX a relay of mediumm.; RR6, "Radio Requete de Vitoria," Vitoria ; wave CJCB, Sydney,Nova Scotia.Their QSL FEI1, "Emisosa Falange FEI1,-" Vallodolid ; EAJ8, card, of not too attractive appearance, gives the "Radio Espana," San Sebastian, 41.65 m.; EAQ4, wavelength as stated above and power 1,000 watts, "Radio Madrid," Madrid, 42.58 m.; and EAJ28. but fails to give their schedule or other interesting Bilboa, 41.4 m. details-infactthecoveringenvelopeismore OtherEuropean newscomesfromPortugal, attractive-it bears several photos-and is indeedwhence we learnof CT1AA's new call, CS2WA ; more informative ! Venezuela with YV6RC; "Radio Bolivar," Bolivar, Writing of QSL's reminds me of the speculation in on 46.73 m., where it is often well heard from 22.45, the short-wave sphere concerning the fate of CB615, or so, using Westminster chimes each' quaiter-hour or "Radio Service," the broadcaster that made such coupled to the call "Radio Bolivar (phon. Bo-lee- a sensational debut on 12,300 ices. some time ago, va), Ectacion YV6RC en ciudad Bolivar, Venezuela, and thanks to a verification I am able to state that America del Sud," and numerous chimes and gong this station is off the air and has been replaced bynotes between announcementS; Colombia, where CB1170 on 11,700 kcs.,or perhaps a little nearer to.11J4ABE, "La Voz de Antioquia," Medellin, appears 11,895Ices.,although officiallythe former.The to have wandered from its original wavelength in card from CB1170 is a little unusual in design and four of 48.83 m.; Martinique with its sole repre- bears a type -written message of verification, being sentativeFZF6,"RadioMartinique,"Fort-de- accompanied by a circular from the owner, Otto France, continuing to put in a good signal on 30.98 Becker, in which it is stated that CB615 has been m. between 23.45 and 00.45, and finally the tidings taken over by him and that CB1170 has an outputthat yet another Venezuelan is to make its etheric of 1,000 watts, which certainly makes it appear- bow with the call -sign YV5RR on 51.43 m. ere long. since CB615 had the same power-that CB1170 and In conclusionI am very grateful to R.M.L. CB615 are one and the same.The letter continues (Reigate) for pointing out the error in the Cana- toexplain that the "Anglo-American Hour"is dian'scall -sign,andforhismost encouraging broadcast thrice weekly, on Tuesdays, Thursdaysremarks concerning my last article, and to G.W.P. and Saturdays, from 23.00 to 23.45, and that the full (Alfreton) for similar information. operating hours are daily 16.00-20.00 and 22.00- 05.00.The full title of CB1170, as announced, is ATTENTION !-A NOTE FROM "AVO" "CB89 y CB1170, Radios Otto Becker, Santiago de We should esteem it a favour if you would kindly give Chile" and the address "Radio Otto Becker, Camila publicity to the fact that the following instruments were 706, Santiago, Chile." stolen from a representative's car in Islington on Novem- ber 2. Latin America stillpredominates the 49 -metre Universal "Avometer" No. 66,34.31. band at night and early morning, but it is amazing D.C. "Avometer" No. 6594. Universal "Avominor" No. U.23257-16. the way in which many of the stations desert this D.C. "Avominor" No. 4193146. band in favour of the 31 m. channels.Latest addi- "Avo" Oscillator No. 3150. tion is HJ7ABD of Bucaramanga, already introduced "Avodapter," "Avocoapler." No 'word of serial numbe s "Avo" Exposure Meter No. 14015-107. to you in these pages, which is without much doubt Smethurst High -Light Meter No. H.101.2-87. HJ2ABD, "Radio Bucaramanga," operating with a "Avo" lightMeter, for measuring candle power No. new call, and I understand that others may shortly H.1020-37. 1-"P" Type Zeva Iron No. 57.16. follow suit. 1-"P.O." Type Zeva Iron No. 0.109. "Radio Belgrano" on 31.1 m. approx., has, as We are sure you will appreciate that with the tens of partly prophesied, turned out to be a Uruguayan thousands of instruments we have supplied to the trail- many are stolen from time to time, and we have a black' relaying a Buenos Aires medium -wave broadcaster, list upon which we record the serial numbers of such instru- namely LR3, whose title is that heard so frequently ments, most of which are returned to us for repair in due course. Upon receipt of such instruments we advise the from the relay-CXA8, for that is its call -sign and original purchasers, and in most cases are able to return the location is Montevideo.The address I do not same to the rightful owners. We are sure your readers will know, but have been told that reports should be recognise that our system may be of great help to them in addressed to LR3, "Radio Belgrano," Buenos Aires, the event of their losing any "Avo" products.-THE AUTo- MATIC COIL WINDER AND ELECTICAL INSTRUMENT although when I have the time and inclinationI CO., LTD., Winder House, Douglas Street, London, S.W.1.

5 THE SIMPLEST TRANSMITTER WithDirectModulation -- One Valve- No Neutralising Designed by GSGQ

THESIMPLEST 40 -metre' phone / cwtransmitter simple c.o. circuit, hut it must be remembered that. possible.That's what we set out to design, and the itis being used as a final stage, not as a driver little rig shown on our cover is the result. No neutral- unit, so maximum efficiency must be obtained. The ising, one coil, one tuning condenser, one valve. The particularcoilused was chosenbecauseitis valve is modulated direct from the microphone, no efficient, and also because when a larger transmitter modulating valve or speech amplifier being necessary isbuilt,it can still be used, so on the score of with a sensitive microphone.Plug the key into the economy the extra shilling or two spent, is a worth- right hand jack, and you are on c.w.; plug the mike while investment. in the left hand jack, alter the bias tapping and For those who prefer to make their own coils, the you are ready for 'phone.Change coil and crystal. winding consists of 16 turns of 14 s.w.g. wound on and you are on another band.In fact a single a 2k -in.outside diameter former.Although the controltransmitter ! Can anything simplerbe commercial type coil is centre tapped this is un- imagined? necessary for this particular circuit, but it is useful The circuit is our friend the regenerative pentodein that the coil may be used for a neutralised p.a. using one of the new Mallardshould one be used at a future date. crystal oscillator, Three turns are wound on the h.t. end to provide. PVO5 /15 r.f.pentodes, with suppressor modula- feeder. tion.20 watts output on c.w., 5 on 'phone. a "link" for coupling to a low impedance In choosing the circuit crystal control was thought The base may be drilled to take these two extra to ke an absolute necessity We didn't want to useleads, but this is a matter of choice for the indi- more than one valve in the transmitter proper, but vidual constructor. In the photo it will be seen what valve should it be?A triode would have that this winding is taken to two terminals mounted given somewhat less output with considerably more directly on the coil former. crystal heating; a tetrode (beam tube) would have given equal output, but with both these types modu- Construction lation presents difficulties.It would have to be The only point to be watched in the construction either Heising, needing a fairly large modulator, oris the mounting of the tuning condenser (Raymart grid modulation involving difficult adjustments. TC40).Thisis mounted on an Eddystone con- A pentode can be suppressor modulated.It isdenser bracket, but it will be seen that the con- about the simplest form of modulation touse. denser has two .nuts on the fixing shaft.These are Adjustments are not critical, the bias can be varied not the same thickness, so they are removed and over a wide range, quality is excellent, and modula- the thinner one is placed nearest the condenser, the tion power required is less than a watt. thicker one being used to secure to the bracket. A well -shielded r.f. pentode as a straight crystalThe extension rod consists of a length ofI -in. oscillator is not a very satisfactory arrangement, ebonite rod. beam tube isfar better.But when regeneration is applied the r.f. pentode gives more output with minimum crystal heating than any other type. 500V H T+ Regeneration may sound complicated, but all that is required is the .0002 mfd. condenser, and the r.f. choke in the cathode circuit.Note how the use of LI an indirectly -heated valve saves trouble. A directly - 20,,000f1 heated one may be used, but then filament chokes 40 are essential, a bothersome procedure. mmFd Layout A departure from the usual regenerative pentode circuit is the addition of a minute capacity between 50.000 SUPPRESSOR grid and anode.Thisisnecessary because the BIAS PV05/15 is ; a shieldedr.f. pentode, designed to work as low as 5 metres as a straight amplifier, and some external capacity between grid and anode is necessaryforsatisfactoryoscillation.Thiscon- 001 m Fd denser is made by connecting a wire to the grid (on the valve base for the crystal), running it through the chassis and wrapping it round the insulated lead from the valve anode to the coil.The length H T- of "wrap" necessary.is about two inches. 0002 mfd The transmitter is built on a 12 -in. x 8 -in. x 4 -in. 12 VOLT aluminium chassis, fitted with a 12 -in. x 12 -in. front 3 AMPS panel, by Scott -Sessions.On top is mounted the (Cerr topped) valve, crystal,coil,and tuning condenser.The Raymart coil may appear ambitious for use in a

6 The crystal, a Valpey (Webb's Radio) is suppliedpower is required. With 350 volts the input to complete with holder, and this fits into an Americanthe anode was about 14 watts. 5 -pin valve holder.As many amateurs do riot have This little transmitter is one of the most pleasant a 12 -volt filament supply available from their usual outfits we haVe ever handled.It is absolutely fool- transformers, a separate filament supply is incorpo-proof, puts out as strong a signal as can be desired rated, and this can be seen mounted in the centre, for ranges up to 1,000 miles, and when we do want under the chassis. to scrap it every part can be used in the construc- The 'phone/c.w. jacks are of the Igranic closedtion of another larger transmitter.Reports will be circuit type, and are insulated.Care must be takenanticipated and in this connection the transmitter if deviation from this pattern is contemplated. is available for loan purposes to clubs, and will be The power is brought in to a five -pin valve socketsent complete with filament supply. An h.t. voltage at the rear of the chassis.The anode pin is for of 500 will be necessary, and owing to the weight positive h.t., the filament pins for minus h.t. and clubs are expected to provide it. positive bias (suppressor) and the centre pin for negative suppressor bias.The grid pin is left free. C.W. PARTS REQUIRED When the set has been completed, and the power switched on, the total h.t. should not exceed 85 Chassis-Scott Sessions. tnilliamps, non -oscillating.As the tuning condenser Coil (7 mc. ready wound)-Raymart. is rotated, the valve will start oscillating, and the Coil base-Raymart.. i.t. milliamps will drop, the average figure being 25 2 stand -off -insulators (type SX)-Raymart. atilliamps,this including both the anode and the 1 40 mmfd. cond. Rayinart-(TC40). screen current..The screen alone consumes between 12 and 18 milliamps. Tuning dial-Eddystone (1077). For c.w. operation no suppressor bias need be Bush and ebonite rod-Bulgin. used, and the centre pin of the rear socket can be Crystal and holder (7 mc.)-Webb's Radio. connected to one of the filaments.This should be 1 5 -pin American valve base (chassis type) done when tuningup.When thetransmitter -Clix. oscillates, as shown by a neon bulb or by a meter connected in the h.t.circuit, the aerial may be 1 5 -pin valve base (chassis type)-Clix. connected, and the key inserted in the right hand 15 -pin connector-Bulgin (P3). jack.Keying takes place in the cathode return, so 1 8 -pinside contact valve base-Bulgin the transmitter can be used for "break-in" work. (VH24). For c.w. use, a small positive bias may be put 1 50,000 ohm resistor (1 watt)-Erie. on the suppressor (say 30 volts), but this is only 1 20,000 20 -watt resistor-Bulgin (PR38). necessary when maximum power output is required. Whenever alterations are made to the tuning it is 1 250 20 -watt resistor-Bulgin (AR250). always wise to keep the suppressor either at earth 1 r.f. choke-Eddystone (1022). potential, or negative.It helps prevent the anode 3 .001 fixed condensers-Dubilier. current " running away " when out of resonance. 2 insulated closed-circuit jacks--Webbs. Removal of the key keeps the carrier on.For 'phone the secondary of the mike transformer is 1 12 -volt, centre -tapped fil.transformer -- connected to the left hand jack, and if a sensitive All -Power. microphone is used, there will be ample power to 1 PV05/15 transmitting pentode-Mullard. fully modulate the carrier. Underte,t of B T S carbon mike was used, and with six volts on it gave excellentre- sults.If an insensitive mike is used, such as a Reisz, an amplifier will be needed, and the one re- cently described in these pages will be found to give more than sufficient audio. Infactthe trouble is to keep the modulation down, so sensitive is the valve. The modulation being arranged, the correct bias should be put on the suppressor, a voltage of about forty volts negative being suffi- cient. Results The aerial used for'7 mc. was a, doublet, centre fed with 75 -ohm feeders, connected to the link on thecoil. With 350 voltsh.t. continental stations were easily raised,signal strengths of R6-8 being obtained.This h.t. voltage was found quite enough forall ordinary purposes,but can be increased to 500 volts if additional "RADIOQUEST" Armchair Understanding of Radio Riddles

Conducted by RAY CORTON

FULLY HALF the queries that have been raised by 30 -metre doublet would have a top span of roughly Radioquest have been concerning receiving aerials,48 feet, somewhat less than the average broadcast so it will be as well at this stage, even at the ex- aerial. pense of retarding what I had hoped to cover this A doublet or ordinaryhalf -wave aerialisim- month, to deal with elementary aerial design.I possible for most of us for medium or long -wave have stressed that an ordinary broadcast aerial can reception (even if the G.P.O. permitted it) owing be used with considerable success for short-wave to the enormous length required, so we have to use listening.That is all very well up to a point, but the less efficient Marconi type, but on short -waves as already explained, the greater the amount ofwe can take full advantage of the great increase signal picked up by the aerial the less the amplifica- given over a narrow band and with the doublet, if tion required in the receiver, and the less the ampli- we are limited to one aerial only, we can use it as fication the less the internal noise in the receiver. a Marconi T for wavebands other than for which What is lost by an inefficient aerial cannot be put it was designed.I will return to this a little later. back by the set, at least not with the same freedom Aerials erected horizontally are directional, that of background noise, so for logging dx we cannot is they receive better from certain directions than over -estimate the importance of a good aerial. from others.With the T type there is little pick-up from the directions in which the ends of the top The chief requirements span point, but if we erect it vertically itwill The two most important characteristics an aerial receive from every point other than immediately should possess are, of course, a good pick-up and a above or below it. high signal-to-noise ratio. The first is easily obtained A signal from a short-wave station does not travel by the employment of an efficient conductor such asalong the earth's surface, but, as we saw in the copper wire erected in a high position where losses firstRadioquestarticle,inaseriesof hops- are at a minimum, that is, well away from build- refracted (or reflected in the case of certain wave- ings, trees and other "screening," especially metal lengths) by the ionized layers above the -arth and objects such asdrainpipes,guttering,telephone reflected by the ground.The signal thus reaches wires, etc. the aerial at a definite angle.Not infrequently As the amount of energy picked up by the aerial ithappensthat a well -designed and otherwise is directly proportional to its height, this is a very successful aerial simply will not pick up signals important factor and the maximum height per- from a certain country, due tolocal conditions. mitted by local conditions should be used to full This can often be overcome by varying the height. advantage.When we speak of the height of an when they come in at full strength-a tip worth aerial we really mean its effective height, that is, not bearing in mind if you find some particular country merely the height above ground level but the height elusive. above surrounding obstacles. Feeders Marconi and Hertz aerials To the beginner, the terra feeder probably sug- Aerials may be roughly divided into two classes : gests transmitting aerials, so it will be as well at (a) the untuned or non -resonant and (b) the tunedthis point to make it clear that transmitting aerials orresonant.The Marconi,as used for normalare just as suitable for receiving as they are for broadcast reception is of the former type and con-transmitting, their particular properties remaining sists of a wire of indefinite length used in conjunc- unchanged.The customary method used by trans- tion with an earth or counterpoise.It usually takesmitters to test their aerial is by trying it for recep- a form of a T or inverted L (names which describe tion.It is the aim of a transmitter to transfer all its shape) and is brought into tune with the fre- the energy into the aerialitself.Obviously the quency used by tuning adjustment of the receiver's ideal means of doing this would be to position the aerial circuit. transmitting apparatus up beside the aerial.This The tuned aerial, or Hertz type, is designed to being impossible, the next best thing must be done. work on a certain band.As we saw last month, the The energy is fed through a feeder system which of wavelength to which a wire will tune isdirectly itself is unable to radiate, usually transposed cable dependent upon its length, thus it can he cut toor separate wires held in position by transposition resonate at a given frequency and no earth or blocks. counterpoise is necessary.The most popular form We shall continue next month with a study of this aerial takes is the half -wave, which, as its name feeder systems for the receiver. suggests, has physical dimensions of half the wave- length it is intended to work on.At the wave- length for which a doublet isdesigned,say 30 metres, it gives over twice the strength but this TURN TO PAGE 31 falls off as we depart from that figure :Ind at 25 FOR metres the reception would be merely the same as with a normal aerial of the same dimensions. A READERS' BARGAINS

8 MR. EVERYMAN TRIES A COMMUNICATION RECEIVER

MANY PEOPLE, even keen short-wave listeners, seemRME69 in common with others has 11 knobs.It still rather puzzled as to the exact position in theis utterly impossible without having every part of realm ofradio held by communication -typere- the set under control to bring a weak distant station ceivers.Possibly the terms"single -signal"and through a half -a -dozen locals and the adjustment "communication" suggesting one class of reception of these extra controls gives that flexibility needed only is responsible for the impression that thesefor this purpose.But for broadcast listening only receivers are unsuited to general use-an idea sup-two knobs need be used once the others are . set. ported by their severely practical appearance. TheyTo prove this beyond doubt this receiver was in- certainly look to be more at home in a receiving stalled in a household of the least technical listeners station or laboratory than a drawing -room, and yetpossible and their normal receiver rendered inoper- their severe lines cannot be said to be completelyable so they would have to resort to the RME69 for out of harmony with modern furnishing schemes. medium -wave programmes.High fidelity reproduc- The almost exclusive use of them by transmitterstion was obtained by them from scores of broadcast has rather given the impression that they are unsuit-stations without difficulty once they were told that able for short-wave broadcast reception, so it wasthe needle of the carrier level indicator had to be decided to try out some of them purely from the"tuned" to the maximum reading irrespective of point of view of the novice, as opposed to thevolume.Yes, Mr. 0-v-1, even when they tried the expert. short -waves they found it much easier to handle than they would your three knob affair which works The R.M.E. 69 wonders in your hands only.In fact these BCL's One of the best known receivers of this type, an expressed disappointment when it was taken away RME69, was supplied for test purposes by Messrs.from them "just as they were getting interested" Webbs Radio, 14, Soho Square, W.1, and it wasas they were receiving stations they had never felt a review of this receiver's performance underheard free of interference before. everyday conditions would be of greater interest To an intelligent person half -an -hourisquite than a laboratory report consistingof facts andenough to learn how to use to full advantage the figures which even to those fully understandingflexibility afforded by these extra controls, and after them, are difficult to appreciate if unfamiliar withan evening's practice the veriest tyro should be able receivers of this description. to receive distant amateur stations free of inter- This receiver goes up to 550 metres and so it ference.For simple broadcast use it will do every- may very well be adapted to ordinary domesticthing asked of it ;high selectivity, quality repro- listening. "What about long waves?" you mayduction and a bigger output than most listeners can ask.Itoo, might well ask the same questionever use, with a much greater variety of entertain- "What about long waves ?"High -power long -wave ing listening that the bestofso-called all -wave stations were thought to be necessary to give a widereceivers can offer. service area in days long gone by, but we know Specification better now, and for a number of years they have Now for a few facts about the RME69 for those been superfluousforlistenerswith evenfairlywho are interested in communication receivers for modern sets.Although it has often been rumoured their special virtues.The main tuning dial is cali- that the B.B.C. would like to do away with thebrated in megacycles and wide band -spreading is long -wave National there is always a protest fromcontinuous over the whole range, adjusting all r.f. someone that someone else would be hard hit by it. circuits and not merely the oscillator.The built-in Yet a manufacturer would be thought to be com-coils cover 9 to 550 metres in six steps, .55 to 1.5, pletely mad if he decided to cut provision for long- wave listening out of his receivers although the 1.5 to 3.1, 3.1 to 6.8, 6.8 to 13, 13 to 20, 20 to 32 listenerdoes notreallywant it-which merelyme. with a generous overlap between each.The shows how irrational we humans are-so forall crystalfilterensureshighselectivitywhichis practical purposes a communication -type receiver variable and can be switched either in series or parallel.A built-inaudio -frequencymonitoris can be considered as a serious competitor to an all -operated by pulling out the volume control knob waver in choosing a receiver for general listening. which also serves as a send/receive switch, leaving Deceptive appearance the heater volts on and removing the plate voltage from the r.f. and i.f. valves.Other features are, Many all -wavers unfortunately have the short- cast aluminium chassis frame, tone control, 'phone wave part stuck on as an afterthought and leavejackautomaticallydisconnecting speaker,8 -volt great gaps in the tuning range so actually theystandard valves,built-in power supply and very should be called 3' or 4 wave -band receivers as the complete screening in every stage. case may be, which gives the communication type Itishoused in an attractive,well -ventilated an enormous advantage in this respect.This is a "furniture" steel cabinet with crackle finish, and is much greater advantage than it appears atfirst obviously capable of standing up to real work and sight.Many of these "in-between range" stations rough handling. are really good "entertainment value" and thus one In addition to being a receiver for reliable com- obtains a much greater effective listening band. munication work the RME69 can truly be described Now for the frightening appearance of communica- as a delightto handle for dailyall -useful -wave tion receivers-they look difficult to operate and the listening.

9 AN AMATEUR SUPERHET WITH LOW NOISE LEVEL This receiver should prove an alternative for the amateur who cannot afford £20 for a commercial set, yet requires selectivity with t.r.f. noise level By R. C. HISCOCK

Tars RECEIVER here described was designed to over- suppression.The frequency changer is a triode- come QRM-the bugbear of short-wave reception. hexode valve-no interaction was found between To achieve this end superhet selectivity had to be oscillator and hexode, and the cost of an extra introduced, yet weak signals were now difficult to oscillator stage is saved. receive because of excessive noise, and in the course As no a.v.c. is required, the second detector is a of finding a suitable circuit the following arrange-triode valve operated on the leaky grid principle ; ment was arrived at.It would not be extravagant this valve ensured a minimum of noise, and the pen- to claim that this receiver has the low noise level of tode second det. only increased the noise and spoilt a t.r.f. rx, with 4-5 kc. selectivity. theregeneration.An 1.f.pentode providesthe The minimum of valves was not aimed at with a output. view to reducing expense, but was found to give a better performance than a multi -valve single -signal Regeneration super when conditions are bad.The cost of this set The triode second detector is an unusually versa- is well within the reach of the average purse, whereas tile stage.Here a single valve performs the func- a s.s. super is not. tions of three; it operates as a conventional second Radio -frequency amplification is provided by adetector, the use of regeneration lends additional sharply tuned h.f. pentode stage,as this boosts amplification to a signal much the same as an extra signals considerably and provides excellent image i.f.stage.At the same time thisregeneration VI I V2 obviates the use of a beat oscillator for c.w. recep- I.F tion. L.F- Thus having eliminated a number of unnecessary components plus an extra valve, we have kept the noise and cost lower, without sacrificing any desired quality. A switch placed across the regeneration

1 condenser acts as (a) a noise reducer (by shorting CDII osc 02 naDet. out regeneration) and (b) a c.w. 'phone switch- o although 'phone can be received with the reaction in circuit. Lel H.T.+ )1111.1114U

RE-GEN: H.T+ H PC 50000 0 002 H.T.+ J, aidI 0- BANDSPREAD I / L F -C L F BAND SET 50,0000 C/W PHONE C,./ H F -C 2 .,- of mFd PHONE- JACK C> VOLUME 0002 mfa SPEAKER JACK /-\ 2 mFd Mn/ num \_L

TO AERIAL TRANSFORMER

20.0000 50,0000 H.F EC Osc: 2nd Det 10 Components tor section, or signal wobble will result.Valves and A Bulgin C5F 465 kc. i.f. transformer was used, coils were all screened, in addition to this the h.f. as this has the extra reaction winding included atportion was completely boxed in with aluminium. one end.The condenser should be a sturdy slow- motion job of .0005 mfd. capacity. I.S.W.C. BIRTHDAY BROADCASTS Decoupling condensers in the h.f. portion of the Mr. GEO. W. KING, official programme arranger set are of an unusual value.The capacity of .003 of the I.S.W.C., 116, Sheil Road, Fairfield, Liver- mfd. has been found to be the best, and greater pool, forwards the following information : capacities will only result in an increase of noise. This Club celebrates its ninth birthday in Decem- Where both i.f. and r.f. currents are handled a .003 ber, and the following programmes will take place and .01 mfd. are placed in parallel as shown. to mark the occasion : The hexode section of the f.c. has been left un- 1. From OLR, Praha, Czechoslovakia on 31.41 tuned ; the extra coil and condenser make no differ- metres, from 21.05 to 21.35 G.M.T. on Satur- ence, and would only increase cost and ganging day, December 4. difficulties. 2. From 2R0, Rome, Italy on 31.15 metres from 00.40 to 01.50 G.M.T. on December 9. Layout 3. FromRadio-Coloniale, TPAI on25.6 The intending constructor may have various prac- metres, from 4.45 to 5.45 a.m. G.M.T. on tical designs in mind, but the drawing shows the December 24. layout as used by the author.Certainly no insta- A prize of a world globe is offered to the member bility or electrical deficiency was noticed, yet no who sends in to headquarters the best report on the special claims are made for the plan. reception of 2R0, provided he resides over 600 All wiring should he rigid, especially in the oscilla- miles from this station. 01101rfr WwoNmem2DVAecno

Ultra Short Wave Inter- changeable Coil.Cat. No. 1050. Price 1;8d.

Split Stator Transmitting Condenser, 50x50 mmfd. Cat.No. 1001. Price 17/6.

Short Wave H.F. Choke, 5-180 metres. Cat. No. 1010. Price 2 '-.

Microdenser for High Frequency tuning. Calit insulation.Cat. No. 900;20. Price 3,9d.

EDYST Foremost of Short Wave Craftsmen STRATTON & CO. LTD., 1 9 3 8 London Service, 1 ILLUSTRATED CATALOGUE EDDYSTONE WORKS, Webb's Radio Stores, Freeon Request. Bromsgrove St., BIRMINGHAM 14Soho St., OxfordSt., W.I.

11 Hi! Hi! A little nonsense now and then Is relished by the wisest men " W.S. Gilbert. (A Festive Effort by "Centre Tap")

DESPITE THE high demand for Humour, there is ever, the proprietor made a mistake with the change still a vast, untapped source in this radio world ofwhich Ambrose didn't find out until he got home ! ours, although the demand for it is not so great as After he had built up all the circuits he could the less specialised sort which is more easily market- find-most of them enabled him to get the Regional able.Just look round for yourselves. How abouton the loudspeaker and some the National as well, that fellow a few doors down from you who makesalthough not quite so well as the advertisement and the craziest short -wavers imaginable?Why, youpublished details led him to believe, but that, he have to laugh every time you think about him and was told upon enquiry, was because he was living in his comic hay -wiring! a blind spot-he hit upon a new idea.That was to take a bit of one circuit and a bit of another and "Things to come " blend them into one receiver.The results were I have always considered that Ambrose Fander-about the same and he had the added satisfaction mere is the world's best example of this type and of feeling that at last he was a designer. I have already attempted to persuade the Editor Then, all of a sudden, like a bolt from the blue, to let me write him up in the "Round the Hamcame the metal chassis.Ambrose still maintains to Shacks" series.After all, there is no reason why itthis day that he, and he alone, was the first con- should be limited to hams-why not listeners andstructor to think of using an inverted biscuit box constructors? Ambrose Fandermere has got a shackfor a chassis.Hundreds of others copied him but -quite a modest affair it is true, but he built it it was his idea first. himself out of practically nothing so to speak, which Ingenuity must be considered all the more to his credit.I He still uses biscuit boxes both for his short - specially interviewed him for the purpose and it wavers and broadcast receivers, but it meant adding seems a shame that such good material should bea hammer and a nail to his collection of tools.He wasted. points out that it is much easier to punch a hole Ambrose is a real enthusiast.So much so thatthrough and if you do it from alternate ways, that instead of sticking to ordinary design he has alwaysis, one from the outside and then one from the tried to strike a new note. He first took an interestinside, very little disfigurement results. With a large in radio during 1924 when he exchanged a bucksize biscuit box there is an enormous area available rabbit and a parrot cage for a crystal set with ato add components after the set has been built, valve amplifier (less valve) and an h.t. battery whichinside, on the top and on all She aides, the one snag had given more or less trouble -free service for overbeing that itis difficult to get the nuts on the eighteen months. He regularly dismantled and re- component -holding -boltsafter the first few parts assembled this outfit with minor alterations, alter-have been placed inside the box.However, with nate Tuesdays and Fridays until the ebonite panelcharacteristic ingenuity he has devised a method of wassocompletely smotheredinholesthatit securing them with pieces of bootlace threaded crumbled away in his hands. through with the aid of a football -lacer. Ambrose has not yet applied for his A.A. licence. Forethought He is much too busy at the moment designing a By that time, fortunately, simpler home -construc- multi -purpose receiver.In its final stage, he hopes tion had become the vogue.Anyone, so the adver-to embody an egg -boiler, bacon -slicer, radio -gram tisement said, could construct the "Roof -Raiser"and a swivel -mirror (for shaving purposes) as well Three in a half -an -hour with the aid of a screw-as a number of other useful sundries. He has found driver and a penknife.This appealed most stronglyit impossible to house all this equipment in one bis- to Ambrose, he felt that after all even if he didcuit box so he is using three which are placed on want to alter or re -build it twice a week it wouldtop of one another in rack form. By getting boxes only take him half -an -hour a time, and it would give of slightly varying sizes and mounting all the com- him more opportunity to listen, especially as he wasponents on the outside of the top one and the inside very keen on getting foreign stations like one of theof the bottom one, he hopes to make it collapsible fellows at his office claimed to.Also the part aboutand thus add the further advantage of portability. the penknife and screwdriver attracted him as heAs it will be too heavy to carry about, pram -wheels already possessed them. will be fitted to the base and an oil -can included in He bought a kit of parts(less the bits he feltthe kit.A de luxe model is to be built later with usable from his previous receiver) from a little shopa caterpillar chain around the wheels so that it can down a back street in the East End and becausebe taken upstairs when required. the proprietor cut one-and-ninepence off the price, Ambrose has approached many leading manufac- Ambrose said he would go back there when he turers with this outfit, and has pointed out it can wanted to buy anything else-which he hoped hebe marketed profitably if only enough models are wouldn't.So the proprietor said he would make itproduced to ensure a low retail price.He says that one-and-elevenpence discount instead, which pleased even if they don't sell in the normal way they can Ambrose immensely and he told the proprietor heeasily be disposed of really cheaply in junk shops so would also recommend his friends to go there. How- they will all be sold in any case.

12 On the Amateur Bands " Ham" News by G5GQ

"DUPLEX 'PHONE should be stopped.""Tell us howreference or involved excuse.It shows you have duplex 'phone is worked."So which ever way Imade good use of your A.A. permit, and proves turn I am going to be caught by someone.Bestthat you are capable of building and using trans- thing is for me to fall from my fence and bouncemitters. from one side to the other ! Experiments warranting the use of a full aerial Duplex 'phone has the very obvious advantage ofworry many would-be hams. Two thingsI have saving repetitions due to QRM; the ham at theoften wanted to try, but never seem to have the other end can stop until it is clear.Against thistime for, are tests with aerials.Directional aerials other hams complain that stations stick on the airare beyond the scope of most of us owing to the and take up space unnecessarily. room required.But there is no reason why small Well, it is annoying to switch on and find a stationones, suitable for the average ham, should not be working duplex dead on your frequency, but youdeveloped. do know he is there.If he were working send - The signal strength of a station depends on the receive be would probably land on you when you current in the transmitting aerial.In a dipole this had just got a contact, which I always think iscurrent reaches its maximum in the centre, dying worse than having to keep off because duplex isaway towards each end. How much of a dipole being used on your frequency. need be used for radiation purposes?Its, length When the carrieris on continuously you know can be reduced by coiling up each end, making room that QRM will be bad at that spot, so the best thing for more dipoles in the same space. to do is shift your own frequency.Only got one Little work has been done on these lines, and the crystal?Then put a piece of cigarette card betweenamount of aerial that can be coiled has not been the top plate and the crystal, it will move yoursettled. frequency just the few kc. necessary to clear. The other scheme is to vary the angle of propa- The use of duplex has every advantage, the abusegation by means of a reflector under the aerial. of it is the cause of the outcry against it. Hams come Either its distance from the aerial can be altered, on 7 mc. with 100 watts or so, put R99 signals all or else some "tune" phasing scheme can be tried. over the place, leave their carriers running for a Twodon'ts-don'tshowaradiatingaerial couple of hours at a time, and then wonder whyattached to the transmitter when submitting the others complain.If duplex were used with 10sketch for A.A., and don't ask for a full ticket watts, and QSO's limited to half an hour maximum, because you want to try some modulation system, most of the complaints would cease.The funny it can be tried on A.A. just as well. part about it is that duplex is supposed to save time on the air, yet hams who with send -receive can only Lightning spare ten minutes carry on for ages when they get Correspondence . with G2PC raises the old ques- on duplex. tion of lightning risk.Are we to protect against a The trick in using it is to use only a few feet of direct strike, or only to. provide some means of dis- wire for aerial, and no earth.A.V.C. should bechargingtheaerial?Iremember seeingsome switched off, and manual control used.With aphotos of a direct strike on a church steeple.It decent superhet I can work within 20 kc. of my ownwas lead covered, and as the lightning approached frequency, but with a t.r.f. job there has to be 100gaseous lead rose from the steeple to meet it!A kc. between the two frequencies. million -odd amps would not worry much about our Years ago I used to work 5IN with duplex 'phone '1/22 earthing cable, so it seems that if lightning on 200 metres.He was about six miles away, andis going to strike the best thing is to be out ! we had R9 signals each way with 15 volts on the Chargedaerialsare aneasierjob,a simple p.a.Never had a spot of bother with broadcastaerial/earth switch sees to them, and the sight of either. the spark when the aerial is earthed always amuses Licences visitors. Was tackled at the local club on the subject of Personalities licences.One lad told me that he used to look Calling in Webb's to see G2NO, I ran into Jack upon licensed hams as littletin gods, but after Paddon, G2IS.He seems to be a world-wide ham. meeting them he decided their knowledge of radio Over in New York they asked me whether I knew was inferior to his.He thought there was some sorthim, another ham back from a job in Paris had run of formula for getting a ticket, and asked me to say into him there.I missed him for a time and found something about it in these notes. he was in Africa,assisting in making thefilm The best thing in applying for a licence is to be"Sanders of the River." honest.Ask for the A.A. permit by saying that He has been cursed with home -brewed mains, 50 you want to get experience in handling transmitting volts d.c., but has just had a.c. put on, and says gear. Then, when you get it,experiment withthat he intends to come on the air with enough simple transmitters, keep notes, and when youpower to work through the terrific QRM prevailing. apply for your full ticket you can tell G.P.O. what He regards radio as pure engineering, draws scale you have been doing. A well -designed, home-madeplans of everything he intends to build, and when transmitterisbetterevidence(especially when it is built it makes professional gear look amateur, supported by notes on the snags met) than any (Continued on page 38.)

13 " HOW CAN I MODULATE THE BATTERY TRANSM ITTER ?" AND SIMILAR QUERIES ANSWERED BY G5GQ

I HAVE HAD so many transmitter questions shot at Thus the drain of the p.a. stage, plus the modula- me recently that I think it worth while dealing withtor will be a constant one of nearly 50 mils., far some of them in the pages of this magazine. beyond the economic limit of batteries.For these The most persistent question is that of addingreasons the use of 'phone with this transmitter is modulation to the battery transmitter described innot to be recommended ;it was designed for c.w. the May issue.This transmitter consists of a class use only. B valve, one half used as c.o., and the other as doubler when required.The p.a. was a two -volt Tank Circuit Design power valve, a Hivac PP220. Tank circuits cause a lot of confusion.In the The output of this little rig is between three andbattery transmitter the circuit of fig.1 was used. five watts, depending on how hard the valve is This uses a standard type of variable condenser, and driven.With a couple of hundred volts h.t. the because the circuit is series fed this condenser has to consumption of the p.a. valve is between 20 and 30 be insulated from the chassis. mils., a pretty, tall order for h.t. batteries. But this transmitter was only intended forc.w., and so although the valve takes 20 or 30 mils. with the key down, its average consumption is much less. When allowance is made for the time the key is "up," for spaces between words, and for waits while the operator thinks of what to say next, the actual key "down" time is only about a quarter of the actual time the transmitter is in use. When the consumption is worked out on this basis it will be found to be one quarter of the apparent consumption, and the drain on batteries will be only between 5 and 6 mils., taken on the same basis as a receiver in constant use.Hence battery life will not be a troublesome item. When we try to use 'phone the load on batteries is constant, and is the full 20 or 30 mils., plus the FIG. 1. FIG. 2. mils. taken by the modulator valve. The use of a split -stator condenser (fig. 2) permits Grid Modulation the condenser to be connected to the chassis.It The first thought is to use grid modulation.The also makes neutralisation more or less constant when modulator valve will take, say, 9 mils.The drain the transmitter is changed from band to band.The is high but not high enough to prevent us trying. only objection to it is cost, as the price of a split - But what about the output?Instead of puttingstator condenser is far above that of the more normal out three watts, we only get 25% of that with grid type.If cost is no object, use a split -stator 'tank modulation.Our aerial power has dropped from 3circuit; you will find it far more convenient. watts towatt. On a high -power transmitter the reverse is the Now we must consider signal strength. A signalcase, the split -stator system is cheaper.The reason must be above the prevailing background noise to be isthatnofixedanodebypasscondenseris readable.That's obvious to us all, but what is thenecessary, and on high power this item alone will minimum power required on 7 me. to effect contactscost a couple of pounds-as much as the split -stator withreasonablecertainty?Inpracticeallthecondenser.On top of this a normal type variable British Isles can be worked fairly reliably with 3condenser has to be bought ; so if you work out the watts, but below this figure the background noisecost of the two systems-using 1,500 volts upwards is comparable with the signal strength.I do not-you will find the split -stator more economical. mean to suggest thatwatt will not reach over the country, but it would mean calling time and time Experiments again before raising a station, whereas 3 watts does Many amateurs are anxious to experiment but result in a 75% answer to calls. find most research work beyond their pockets, so we will discuss a pet theory of ours which can be played Heising Modulation with by any transmitter. The answer to the problem is Heising modulation. The problem of using 'phone has been stated With this system the output on 'phone and c.w. is above, butthereisone solution-commoLLED approximately the same, but the battery drain is CARRIER. The normally used form of controlled appalling.To fully modulate our three -watt carrier carrier varies the carrier strength with the modula- we must have 1watts of audio.Even by using a tion strength.It is complex and not worth in- class B modhlator the efficiency will not exceedstalling in a battery transmitter.There is no need 50%, which means that the class B stage alone willto vary the carrier strength with modulation, all we take 3 watts, or another 20 mils.To this has to behave to do is cut the power from both p.a. and added the driver valve consumption, which willmodulator during intervals in speaking.Then our bring the total up to nearly 30 mils. (Continued on page 38.)

14 I. C. S. All Power International Correspondence Schools Transformers Ltd.

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RADIO AMATEUR'S HANDBOOKTransatlantic All -wave Tuning Pack, 1938 EDITION as reviewed in this issue, page 35. Four wave -lengths, Send now for your copy of the 195 - 550,800 - 2,000metres. 15th edition of this very famous 12 - 33,30 - 80, The radio With allcoils,Yaxley-type switching, 3 -gang J.B. Handbook. 20 chapters and over Bar -type condenser, Station and metre marked moving amateur's 500 pages dealing with every pointer full -vision dial. Iron -cored I.F. transformers aspect of amateur radio com- and valveholders on chassis, grey cellulose finished. handbook munication. A atudata AMA.. 104AltOVISAV Completely wired, aligned and tested, ready to use. AA CdIALOACA1,100 RADIO AMATEUR CALLBOOK. Orders now being taken for the Decem- 3 -gang model, HF, FC and IF, 69/6.2 -gang model, ber issue, for delivery middle of month. FC and IF, 49/6, carriage paid. A necessity to every ham and all Sole distributors : who own short wave sets.6/ - per copy postfree anywhere. MAINS RADIO DEVELOPMENT COY., G5KA, 41 KINFAUNS ROAD, 4-6 MUSWELL HILL ROAD, LONDON, N.6. GOODMAYES, ILFORD, ESSEX. Tudor 4046 (Mornings) Dept. M. " PAR EX 77 PRODUCTS PAR -EXCELLENCE. OUR FREE OFFER Have you ever tried to wire a set ?After going to endless trouble to collect all the specified components, some- times after long waiting, you then discover that one or more of the parts are of the wrong type, or unobtainable. CLASS "B" ONE VALVER A GENUINE OFFER as described in March No. completely wired YOUR SET IS WIRED BY and housedina PARE.X" cabinet (as supplied to B.B.C., Admiralty, etc.) EXPERTSFREE EACH SET TESTED AND GUARANTEED. We charge only for the Components Components are as specified and include Cabinet as shown here withchassisand lid EDDYSTONE cond users, coils, etc. 1316 (postage 6d.) "PAREX"Cabinetfor Price £3 (postage 6(1.)With valve £3 9s. 6d "IDEAL" Ileceiver (described in this Meg.) Coils2 9each extra. including chassis and 4 boxes k2. Chassis, Any SetsuppliedREADY WIRED. panel and boxes alone 301- Let us quo'eyou tor" PAREX" CABINETS " IDEAL RECEIVER readywired 18gns. CHASSIS, PANELS, Etc. E. PAROUSSI, 10 FeatherstoneBuildings, High Holborn, W.C.1Phone : Chancery7010 15 From S.W.L. to Full Licence3.

By CHARLES WHEELER

BEFORE GETTING DOWN to the p.a. I decided to re- the voltage feed -back is in opposite phase, and the wire and make a neat job of the oscillator -doubler, two cancel out.This was shown by tuning the tank and try out another valve.When finished I pressed condenser, and seeing that no variation took place the key and expected to get a reading somewherein the meter reading of 9 mils.: it was, however, between 10 and 20 ma. in the meter, so you cannecessary to readjust the doubler condenser to get imagine my surprise when the needle flicked acrossthe full nine mils. and the valve glowed in a very pretty but even By the way, negative of meter goes to grid ;if more disconcerting fashion.Well,I didn't leavecurrent flows in the opposite direction the meter it like that long, but checked over my connections,will tend to give a negative reading. and, believeitor not, those of the valve were The stage has now been neutralised, and we can reversed, despite the fact that I warned you aboutget on and bias the valve, replacing the meter by that very thing last month, which just goes tothe C battery, and removing the h.t. fiorn the first show ... ! two stages.I then put 150 volts on the plate of the p.a. valve, which was the PX230SW brought Valve trouble back into service to do good work in yet another That, however, was by no means the end of thecapacity.The bias required to reduce anode cur- trouble, for when the connections were put right therent to zero was 18 volts, and then remembering meter read just under two ma.This time noa tip :"Never be afraid of using plenty of bias," I amount of checking revealed anything wrong, and atput another 9 volts on. last it was decided to give the valve a thorough test.That test showed quite a lot was wrong :it was in fact a wolf in sheep's envelope.The emission of one side, with 100 volts h.t. was 1 mil., and the total emission of both sides, with 220 volts -7. The reason for putting a lot of h.t. on was that some valves have unusually steep curves, and the extra voltage might have resulted in a sudden rise in output. Like most of the stages of our transmitter the name of the power amplifier gives a good explana- tion of itself.The p.a. is an amplifier, to which is applied a drive from the c.o. or doubler, and func- tions simply to give greater output from the trans- mitter. In a p.a. valve there is feed -back from the anode LT+ to the grid, and unless this is neutralised oscillation FIG. 2. willoccur;consequently we need a secondary neutralising circuit in the amplifier, and a means of Three stages working determining when itisneutralised. As there is I replaced h.t. on the first two stages so that all much to say on this subject I will leave it for a few three were working together.Before tuning, the moments and outline the circuit. p.a. was taking about 35 mils., but when in reso- -"Theplate circuit consists of a coil made by wind-nance, this dropped to 6. Wen the circuit is in ing eight turns of 12 s.w.g. wire on a two-inchresonance, we are getting a bigger output, .which former, and a 50 50 split stator condenser.The is of course our aim and so for that reading-the coil is coupled by a small variable condenser to thesmaller the better. grid, forming the neutralising circuit(fig.2).H.T. If you have not a split -stator condenser handy- is applied to the plate through an h.f. choke, whilethey are rather expensive-there is another quite h.t. negative goes to g.b. positive and g.b. nega-good circuit (fig.1) which employs an h.t. by-pass tive through an h.f. choke to grid. A meter is in- condenser.This time h.t. is applied direct to the serted in place of the bias battery to determine centre of the plate coil, and a by-pass condenser to when the circuit is neutralised. earth takes the place of the earthing connection from the condenser.After that, procedure is the Neutralisation same. Now I think I can explain the neutralising opera- By now I hope you have learnt with me how to tion.The oscillator -doubler was tuned for maxi-handle all three stages of a simple c.w. transmitter, mum output and connected through a small fixed and even if you have heard the horrible gurgle which condenser to p.a. grid, no bias or h.t. being appliedarises from and unneutralised p.a. or worried over a to that stage.The next part of the work is usually doubler which didn't double, I feel sure you have described as "juggling" the tank and neutralisinghad some interesting times.Next month I hope to condensers, and consists of tuning the n.c. until its deal with modulation experiments, carrying on with capacity is equal to the anode -to -grid capacity, butour method of grasping the fundamentals first.

16 THE MAINS "S.-W.M. " " IDEAL " STRAIGHT RECEIVER

Preliminary Notes by the Designer

IN irExT moNia's issue we shall be dealing with the special precautions must be taken to prevent the Mains Version of this receiver, as it is certain thatslightest trace of a.c. reaching the grid of the r.f. the majority of readers are more interested in this valve.It was this that gave us the headaches. than the battery set, though the latter has provedSome will say that the problem should not have both popular and successful. presented any serious difficulties if American multi- The "Ideal" Mains Receiver will embody all thestage a.c. operated sets can he made to give a quiet main features of the battery model --which was background under similar conditions, but actually fully described in September, October and November the problemisalittledifferent,because itis -with the addition of a built-in power pack forpossible, in the first place, to cut down the gain mains working.This will be accommodated on aon the high frequencies in such a receiver without chassis very similar to that used for the batteryaffecting sensitivity to any serious extent, while "Ideal," so that the only external connections willsecondly-and even more important-a factory - be for the power line, speaker, aerial and earth, and built mass -production receiver can be screened and 'phones. A monitor -beat oscillator will be incorpo- boxed up in a manner which is not possible in a rated, as before, together with r.f. regeneration and design intended for general consumption and repro- tapped band -spreading,so that the five amateurduction by home -constructors of varing grades of bands covered are each tuned over 80 degrees of the proficiency and experience. 0-100 degree main tuning dial. The design must therefore he kept as simple as Hivac valves will be used, as in the case of the possible, at the same time obaining the utmost from battery receiver, as the results obtainable with theseevery valve in the circuit, and it is really on this highlyefficient valves make their inclusionwell point that the main problem hinges. worth while.In fact, in common with all mains We mention all this because it may be of interest sets when compared with similar battery -operatedto those who are trying r.f. regeneration in a short- receivers, the performance of the Mains Version ofwave receiver, and in the individual case it may be the "Ideal"is noticeably better than that of thepossible to go even further than we can do in the battery model, which is only to he expected. matter of screening and lay -out,since we must always keep in mind the fact that the set has to be Hum designedforeasy reproduction by the average The chiefdifficultyin any mains short-wave reader. receiver is the elimination of hum on the higher frequencies, and in this receiver we have aimed at, At one time, we thought of dropping r.f. regenera- nothing less than a completely silent background tion in the Mains Version, but when we remembered with headphones on ten metres.This is something how striking is the improvement in performance of a problem, as all those who have tried to getthat it gives on the high frequencies, we decided similar results will agree, and has involved muchthat it must at all costs he used in the receiver experiment, as the lay -out and stray coupling effects under discussion. are the deciding factors in the total elimination of hum.To this end, the grouping of thevarious Components stages has been altered somewhat from that adopted As before, the choice of components has been for the battery receiver, the ultimate result beinggiven very careful consideration, and readers may that our effort to ensure absolutely silent headphone take it that the parts specified are not only essential receptiononthehigherfrequencieshasbeen for reproducing the model exactly, but that they achieved. are the best obtainable for the job.This is not Itis interesting to note here that while it wasto say that we consider all other similar components found comparatively easy to obtain a quiet back-inferior, but rather that the ones we have chosen ground under ordinary conditions of reception at thework better together, which is the only reason for h.f. end of the tuning range, the hum came upusing them. strongly when using the r.f. regeneration control in All designers are haunted by the fear that their its most sensitive setting.In other words, withreaders will attempt to build up their set using this control turned down and the receiver workingeither components they may have by them, or parts as a t.r.f. receiver of the "straight" type, the back- different from those specified.Usually, the receiver ground on ten metres was no worse than when turns out a failure, and a black mark is registered using battery supply.But assoon as ther.f. against both the paper and designer concerned. regeneration control was brought up, up came the This does not prevent readers who have so deviated hum-and what' a hum! from the specification writing in to complain, very While this showed that the tuned regenerative r.f.often giving their oath at the same time that the stage was doing its stuff, it also proved that extraset has been built exactly as described !

17 Spanish Nationalist Short -Wave Stations

By W. L. CARTER

iI1TDQING BY what has so far been written in regard Keen listeners may have recognised there are cer- to Spanish short-wave reception, considerable con-tainomissions,e.g.,Santander and the famous fusion exists in the minds of British listeners. When mystery station "Radio Espana en el Frente de one reads of "Insurgent" stations allegedto beMadrid," which operates on two frequencies simul- relaying programmes from Valencia one is tempted taneously on the 40 -metre band. It uses a secondary to "say things." identificationof"RadioAZ,"butinvariably For months past the writer has concentrated uponannounces itself by its full name as well.One or a careful reception of stations operated by thetwo people have written to the press about this Spanish Nationalists, and some most interesting station, giving the impression of its being a real broadcasts have been received here (Midlands) since capture and difficult to receive.I can only say that the Iberian conflict flared up.Almost every leaderit has been received here three times daily over a of note has been heard including the late Generalperiod of months.Those who send in a control Mole, Generals Franco, Moscardo of Toledo Alcazar report to Spain and ask for a QSL acknowledgment fame, the one-armed,one -eyed Miliand'Astray, will get this, but there will be no indication of the veteran founder of the Spanish Foreign Legion intransmitter's location.The reason for the omission Morocco, and a good speaker.That says nothingis obvious, but I can assure listeners that it is a of the nightly peroration relayed by every Spanish genuine Madrid Front station. Nationalist short-wave transmitter from Seville at 10 p.m. G.M.T.The voice of General Quiepo de News from the Front Llano can thus be heard booming every night at I have had some really exciting times with a short- many points on the 40 -metre band. wave receiver during the war in Spain, and it is possible to beat completely the Press in up-to-date An Authentic NationalistRoll information. A particularly notable example of this The list given below has been officially confirmed was my receptionof thelittle radiostation at and may he taken as being absolutely correct. Durango near Bilboa in pre -Iron Belt days.This was only a field transmitter but it sent out quite a ,,tation Call. Location Brea rindMetres Power respectable service, although its musical programmes Radio Espana Bilbao 7.246 41.10 200 watts. were at times sadly deficient in quality.This sta- (EAJ28) Burgos 11.200 21.12 3041 tion, which styled itself Radio Requete en Durango, EA7BA Cadiz 11.284 40 worked a regular schedule until shortly before the EA7BA Cadiz 7.112 12.1/0 19 occupation of Bilbao.I was officially informed that F.E.T.5 Burgos 7.100 12.25 300 F.E.T '21 Ceuta 7.134 12.00 100 Iwas the only person outside Spain who had EA2111, E j ea de Las reported reception of it.The night before Bilbao Caballeros 7.000 12.81 50 fell, the Durango transmitter suddenly announced EA2BA Jaca 11.031 21.38 200 EA2BA laca 7.177 41.80 200 at about 6 p.m. that it was closing down for good .E. T.3 Melilla 7.202_ 11..61 85 and moving on to Bilbao.Its short life had ended. EAME Melilla 7.200 11.66 20 Then even more recentlyin connection with the 11.080 21.30 100 EA8AE Las Palmas 11, Asturian campaign I used to Jisten every evening, EA8AE Las Palmas 7.200 11.66 100 t1 F.E.T. I .as Palmas 7.003 42.33 10 as well as in the daytime, to Radio Requete en el F.E.T. Las Palmas 7.117 41.97 40 FrentedeAsturias. (CalllettersR.R.7).That, F.E.T.6 !'alma de too, had a short life but a fast one while it lasted. Mallorca 7.121 1110 115 ol T .0 Palma de Then, one morning recently, I heard Radio Gijon Mallorca 7.168 11.51 115 change itstone completely.It called up Radio EAIBI, Pont evcdrgi 7.212 11.19 75 Espana de Bilbao (EAJ28) and exchanged hearty EA1B1. Pa ni eyed ra 7.200 11.60 75 EA1BH Pon f (red ra 7.500 10.00 00 greetings. Congratulations were returned amid much Radio Espana San .Cebastian 7.203 41.65 1 1 tr. "Viva Franco" and "Arriba Espana."Other sta. (EMS) tions followed suit, San Sebastian being the first of Radio PizarralesSalamanca 10.630 8.22 1.5 k EA1B0 Sala mama 7.070 12.13 71 watt,. a series, and then I knew Gijon had changed hands.

EA1AV Salas 15.000 21.42 60 I had practically listened in to the end of the war I;AlAY Salas 7.000 12.85 lU in Northern Spain. Radio Tenerife neri I e "El (EA)43) Ta Nero" 10.373 28.92 23 kw. F.E. T.7 Tr e ri f r 7.471 10.14 100 watts. English Programmes lia9A11 T et min 6,996 43.10 1410 EA9AH Tetuan 3.999 75.15 411 The language difficulty at once arises in connec- F,A 9A11 Tetuan 14.030 21.40 Not statcil. tion with listening to these stations, but it need not F.E.T.1 Valladolid 7.006 12.82 400 watts. cause much trouble.Indeed, it is possible to pick F.E.T.10 Vitoria 7.027 12.69 160 R .R.6 Vitoria 7.265 Not stated. up a smattering of Spanish from these transmissions EA2A A Zaragoza as some of. the stations read the official Salamanca (Saragossa) 7.002 42.82 150 watts. bulletin in English.They give also a reading in

18 French, German, Italian, Portuguese, and in one " S.-W.M." Class B Receiver Test or two special transmissions a reading in Arabic.As Thefirststrikingfeatureabout theclass B all these are a literal translation from the original receiver is its neat and tidy appearance.Whilst the Spanish, itis quite simple to follow the Spanish components are not crowded together the wiring is from the English and so polish up one's knowledge, only ofthat pleasant -sounding language.Usefulsta- direct and short.The metalcabinet not tions of this type are Radio Nackmal which is shieldsit but givesit a professional appearance. relayed by Tenerife.This broadcast is often put out Tuning is made very easy for the operator by the by F.E.1 of Valladolid, Radio Espana of Bilbao bandspread and good slow-motion dial.When the (EAJ28), Vitoria which announces itself as Radio reaction control is advanced very smooth oscillation Requete R.R.6, "Madrid Front," as well as EAJ8 is obtained, and this, together with the complete better known as Radio Espana of San Sebastian, absence of hand capacity and background noise, which is one of the very best stations for English probably accountforthe successofthislittle reception.The English programme, which has been receiver.Although one or two blind spots were designed specially for British listeners, is broadcast noticeable these could be eliminated by adjusting the twice daily at 1.20 p.m. and at 9.20 p.m. G.M.T., aerial series condenser. Sundays excepted.The evening broadcast is a good Good loudspeaker entertainment was obtained on one, lasting half -an -hour, and delivered in perfect the strong signals, aircraft stations, especially, com- English by a competent announcer.This station ing in very well.The aerial used (luring these tests has recently greatly increased its strength in Britain was a sixty -foot doublet, only one side being con- by reason of a topographical adjustment of the nected.It was found that American signals could transmitter.I understand that reports of consistent still he received at good strength on nine feet of reception at good strength have been received from wire placed on the floor. Some of the best 20 -metre fone signalswere, as far distant as New Zealand, which is as satisfac- October 14: W1JFQ, BBS, KKP, FLH, W2JMC, tory as any European station might hope for. HYT, ZC, GIZ, MRX, FBA, W3EKU, AFG, FII, Hints W4DLH, OC, W8GKC, HAF, MAT, FNN, MJT, Verification NEX, OKU, NXQ. VE1FQ.VO2Z. SU1WM, Without exception,all Spanish Nationalist sta- FA8GT. SV1CA.October 15: WIJRQ, QM. ZB1L. tions from 11.15 p.m. onwards relay Salamanea, SUISG, WM. CN8AM, SV1CA, KE. ES5D. F8PU. ending at 11.45 with the military News Bulletin in a October 16: WIBLO, JGX, JG. W2IVW, ZC, IUP. varietyoflanguagesincludingEnglish.At the W3DFH. VOII. VO2Z. VO6L. SU1RO. CO6JQ. moment my interest is concentrated on EA2BA, the HBIS. LA1G. LA6N. HA4A. ES5D. IlMI. F3KN, small 200 -watt transmitter at Jaca just south of F8PU.October17:KA1BH. WI ADM, APA. the Spanish side of the Pyrenees.This station W2BIF. W4OC, DXP. transmits in English as early as 3.40 p.m. G.M.T., -A. D. GREEN, Brentwood Amateur Radio Society. including Sundays, and the announcer asks for reception reports.When sendingthese, and the same applies to any other station on the list, I find itcertainly pays to enclose a6d.International Recently Published. Reply Coupon, which has never yet failed to pro- duce a courteous reply.Reports to be of any value at the other end are best detailed over a period- I always report covering an entire week-and I in- SHORT-WAVE variably give full details regarding aerial used, type or make of receiver, weather during reception, alti- tude of residence above sea level, and so forth. RADIO Trivialreportsareworse than uselesstotheir By J. H. Reyner, B.Sc., A.C.G.I., D.I.C., recipients.Many of these stations will almost cer- tainly cease to operate after the Spanish war is etc. ended, so listeners should "get busy" before their This book is a thoroughly up-to-date opportunities pass for ever. guide to modern developments in the In conclusion, it may be mentioned that R.R., or Radio Requete, and F.E., or more simply Falange use of the short, ultra -short, and micro- Espanola, are explained thus.The Requetes are waves. It gives a comprehensive survey the Carlists ;the Falange are the Spanish Fascists. Both have been amalgamated in the organisation of the available data concerning them, now styled F.E.T.or,to giveititsfulltitle, and of the practical methods by which "Falange Espanola Tradicionalista y de las Jobs." they have been harnessed for radio and General Franco has assumed leadershipofthis organisation, according to many of the broadcasts. television transmissions.It shows the Some of the transmitters still operated by them tremendous progress which has been stillpreserve their original names as a kind of made in short-wave radio telegraphy historicalinterest.Bilbao,SanSebastian,and Madrid Front were all formerly Requete stations. during the last few years." Accurate but within the past few months they have changed and up-to-date."-ElectricalReview. their style to Radio Espana. 162 pages.8/6 net (by post 8/10). It is hoped these few notes may be of assistance. Their accuracy is guaranteed correct after a very Order from a bookseller or direct from long period of annotation and exceedingly careful checking.The information given agrees in every PITMAN respectwiththatsuppliedbyofficialSpanish Parker St., Kingsway, London, W.C.2. Nationalist sources.

19 CORRESPONDENCE

THANKS, MR. SPOONER In extremely bad cases, next-door neighbour, etc., a trap would seem to be the best thing, and should be fitted as Youreditorial,October number ofthe"S.-W.M," on near the aerial terminal as possible. Too much trouble, you "Value"-those who suggest your modernity can be nothing think ?Carefulattention butAmericanism maybeclassifiedas totheforegoingenabledthe Britishers!It is a brand of mentality that insularsends -minded out to writer to operate local fone (using a single valve Hartley, Portuguese -speaking Brazil instructions printed in Spanish plate modulated) on 7 mc. for a number of months, at any (how they love each other!) and consistently loses valuable time of the day or night.Complaints? None.-F. I.R Colonial markets because it doesn't care a hang whether TAYLOR (G6YD), Portland Hotel, King's Street, Weymouth. goods suited for home consumption and use are not neces- sarily suited for other climes. No attempt need be made to " EX -OP THREE " ON LEARNING MORSE learn another tongue-"English is good enough for me," so let the blighters learn a "Q" code.This same insular - May a third "Ex -op" give his cxperienc of teaching Morse mindedness cost us in Ihave always found that anyone who has first learned by unpreparedness some.69,500,000,000 "opposites" has to re -learn in the ordinary way.Itis a twenty years ago! longer job; in the first instance, to memorise each letter Go ahead with your progressive policy "S.-W.M.," and if separately, I admit, but when it is done there never is that anything new originates in a black, brown, yellow or other doubt in one's mind as a "P" or "X" comes along-that shirted country let's have it! extra second needed to decide which towriteinvariably means the loss of the remainder of the word. This is Translation Bureau disaster if a P.O. examiner is to check the copy. a If in pursuing your policy you decide to run a bureau for To conclude, let me agree with the original "Ex -op" no the translationof readers'()SL, correspondenceor tech- matter where the code is learned-the best way is undoubt- Diedl dope, you can count on me for :--- edly with a valve oscillator and 'phones. The sound of a FRENCH (F and colonies; ON, etc.). letter in Morse is far removed from its appearance on paper, PORTUGUESE (CT and colonies; PY). and, let us not gull would-be telegraphists-a good operator takes a long time, and a great deal of practice, to become I have been doing this for R.S.G.B. for the past four years efficient. --J.A. KAYF: (213TK),69,Allerton Grange Way, and my "fee"isa stampedaddressed envelope.-N.P. Leeds, 7. SPOONER (G2NS),"Roselea,"17,Swanmore Road,Bos- combe, Bournemouth. " EX -OP TWO" WARMS UP ! Your contributor, C. A. Rigby, in his reply to my com- ADVICE FOR1.7USERS ment seems to think that uttering Morse sounds aloud must The article by my old and %cry good friend, 2NS, in necessarily mean shouting them.Ithinkthe majority October, prompts me to go a little deeper into the matterunderstand that itis only necessary to make these sounds or b.c.1.'s and 160 in., especially as I hope to go on this sufficiently audible to enable one to become accustomed to band in the near future.Rightly or wrongly I think that the Morse equivalents, in a convenient manner. Learning the majority of b.c.1interference is caused in either or both in this way is no more annoying to others in the home of two ways, namely, local ground wave swamp, and har- than someone learning to play the piano, violin, etc.More- monics.If this is so what can the transmitting amateur do over, it is a very poor household whose members cannot bear in order that he may work at any time on this band with- and forbear! out causing trouble ? Referring to the statement "the majority of learners com- Take harmonics first.They can be due to a variety of bine both sight and sound methods," surely there's no, such reasons which need not be gone into now, but some remarksthing as sight method in a system which essentially depends can be made concerning their care.Obviously the first thing upon sound. Your contributor must be getting confused to do ie to discover their existence.It is the duty of every with the Morse lamp as used in the Services and the Mer- transmitting amateur to ensure that the transmitter does not chant Service. radiate any spurious harmonics. I cannot agree that nine out of ten would-be operators The easiest way by far to track down harmonics in the will discard the sound method for a grouping of letters so caseof160metresistobuildasimpledet.-21.f.b.c. as to memorise quickly, and for the following reason. Take receiver (if made with plug-in coils it will also serve as a the Morse equivalent of any letter you like.That particular monitor), then listenfor them when the transmitteris sound is peculiar to that letter only. Now does it seem radiating. This can be achieved by a loud -ticking clock orfeasible that one should first think of the opposite of this some similar device whilst the transmitter is coupled with sound before writing down the appropriate letter?I think the normal coupling to an artificial aerial, which is made as not. near as possible with the same characteristics as the normal Regarding the last paragraph, if Mr. Rigby is friendly with radiating aerial.First tests can be carried out by listening his neighbour be can do him a good turn by pointing out in a near -by room with different lengths of antenna attached that he will never make a good telegraphist while he uses to the checking receiver to ensure that the detector is hot a key as if he were sending with a hammer. The poor being swamped. Should harmonics be found then various fellow is evidently misguided-he is using a gap that is much cures can be attempted until a successful one has been too large and no wrist work.-"EX-OP," Westcliff-on-Sea. found. These can consist of looser coupling; make certain the transmitter is correctly neutralised; that the coupling between xtal oscillator and p.a. is right, different types of A " SUPER " FOR £5 aerial coupler, the use of a Faraday shield, etc. I read with interest Bob Everard's few words on receivers Having found a cure, tests can now be made with the on page 1? of this mouth's "S.-W.M."I quite agree with normal radiating aerial coupled, as near as possible to the him that receivers of the type be mentions are too expensive conditions which existed when using an artificialaerial; to buy. My advice is-build a set to suit your tastes and p.a. drawing same m.a., etc.Using the same checking pocket. For two years I ran an a.c. receiver-untuned h.f., receiver, get a friend to run around various parts of the det.,1.f. and pentode.I'm one of those funny people who immediate neighbourhood, or better still loan the receiverwill not have batteries or 'phones at any price-the starting to different people in order to once more check harmonic up of a local ham about a quarter of a mile from here made radiations under actual working conditions. These checks a superhet necessary. should, if possible, be made as near as possible to the com- Now I'm not a No. 9 hat, just a very ordinary constructor plainants' homes, the results showing how much interference and my only test gear is an old Pifco all -in -one meter, but was due to harmonics and how much to swamp effect. with the aid of last year's Osram valve book and a little What can be done about swamp I think it safe to saycommon sense I have built a s.w. superhet which I think that the majority of straight sets to -day use a first detector will be hard to beat in performance. of the variable mu or h.f. pentode type, and in the case of The set consists of f.c.(X41),h.f.pen.(i.f.),d.d.t. and these interference might possibly be caused-due to cross - AC2 Pen-i.f.'s are 485 kc.; energised speaker; switched coils, modulation. The first valve of our checking receiver can be tuning from just below 13 metres to 280 metres in three adapted to these requirements. steps with no gaps (another of my dislikes is plug-in coils) A cure in the case of local swamp can sometimes be and the lot has cost round about £5, the only secondhand effected by the use of a resistance of a few ohms in either parts are speaker and smoothing condensers(8mfd.'s). the aerial or earth lead of the affected receiver; again our The drive is two -speed -8-1 and 61-1-the coils are the new checking receiver comes in useful. In addition to a resistance Wearite P type.I am using a tuned r.f. stage with regener- in the aerial lead an old -type plug-in coil can be tried; or ation in front of the set and very shortly I'm going to put an b.f. choke of the b.c.l. type. the r.f. stage on the one chassis as soon as I can get the

20 extra coils and switching; my R meter is an edgewise tuning The d.c.resistance of the secondary of the transformer indicator and it works on quite weak signals. C.S.33 coupling modulator to p.a.is 200 ohms. The resist- The set really has a first-class performance and I have had ance between centre tap of resistance across filament legs of requests from several friends for particulars; it will "lose" p.a. valve is 200 ohms to either leg thus making a "Y" net- a certain well-known American set costing£1210s. and work of resistance, each leg being 200 ohms. By-pass con- very popular with the hams-it (my set) was tried out against densers between legs of p.a. valve to earth are dispensed one which arrived in this district recently. with-their place being taken by resistances as above. Now I must be one of the queerest s.w. listeners-I have The modulator itself is a GAG valve with plates and grid been at it for about four years and I have not got a single respectively tied together used as a driver to another GAO QSL card-the truth is 1 haven't the money to waste on used as class B mains valve as above and transformer- stamps just to be able to cover the wall with cards.I find eoupled by an ordinary class IT driver transformer. genuine wallpaper cheaper and any coppers I have to spare - W. KIRKLAND (G8FP), 26, Rufford Drive, Yeadon, Leeds. are to make the set more efficient. [Readers are invited to suggest how this modulation sys- Thank you, Mr. Editor, for the finest and cheapest s w. tem works. We have alreadyexpressed our opinionto reading procurable to -day.I should like you to publish a G8FP, but are withholding publication of the reply so that list of call -sign prefixes of the world-one we can cut out readers' views will not he biased. Thanks for the informs and paste on a board-any chance ?-j. ROGERS, 87, Stokes - I ion, GOP.} ley Crescent, Billingham-on-Tees. CRACKLE FINISH CATHODE MODULATION Concerning the mention of "crackle finish" panels iu the You may be interested in the description of the system, of correspondence of this month's Short -Wave Magazine, I pass modulation used at this station (G8FP). The circuit is,I on the following information for what it is worth :-"Crystal- believe, original.I have been using itfor the past four line" enamels consist of a cellulose enamel in which a syn- months and have described it "over the air" many times thetic resin has been dissolved, such as glycerol-phtheith while other amateur stations who have tried it out all con- anhydride resins. The article thus painted has to be heat - firm my opinion of its merit:. For want of a better name treated iu an oven at about 2000 F. for three hours. I have called it cathode modulation and claim foritthe Although I have tried one or two methods without success, following advantages over plate or grid modulation. the necessary synthetic resins can be obtained now from 1. Entire absence of h.f. feed back. Messrs. A. Boake Roberts and Co., Ltd., Stratford, London, 2. Greatly improved quality of transmissions of speech, E.Hoping that this will be of some use.-R. W. CRAIN- especially from comparatively cheap microphones. The FIELD, 9, Southfield Park, North Harrow. microphone in use at G8FP is theG.E.C."Home Broad- caster" and since modulating by this method reports have asked ifI have scrapped old mike and gone in N.R.S. RESIGNATION for transverse current mike.I have noticed the same A few months ago the National Radio Society came into improvement ou other stations worked who have incor- existence and I held the position of honorary secretary and porated this modulation system. treasurer. 3. Depth of modulation seems to be constant irrespective From a handful of men the society rapidly grew to an of power of carrier (this probably within limits), for organization of hundreds of members, and little imagination without any alteration to modulator or "gain" I have is necessary to visualise the enormous amount of ordinary received the same reports-varying between 85% and 95% correspondence entailed, a burden by no means lessened -when using it on a 46 valve (M -volt filament) using by the QRA and other services, and the work of replying 8 to 10 watts and later with a T20 (7!:,' -volts filament) to suggestions and so forth. The time has now come when using full 25 watts. the latter, alongside the pressure of my professional activi- thanIfeelI can cope with adequately. HT+ Consequently, with regret, I have tendered my resignation. However, in resigning my position I am reluctant that its members should suffer in the least financially; indeed, H.FC wish the society to be able to progress from a firmer basis than attended my own endeavours in this connection. The amount received by me as subscriptions is £19 9s. Od., PA. VALVE which represents 389 paying members atIs.each.I am 46for 10WATTS passing back to the society the whole amount received b3 T20 P25 " me for subscriptions, and paying all the headquarter ex- penses myself. TO FDor The proposal has been made to me that at some time 05C, during the futureIshould reconsider my decision and perhaps take up the position of treasurer; but I desire no erroneous notion to be held on that point, my plans for PA.TANK the future being such as to render such acourse very COIL unlikely, not to say impracticable. I would conclude with thanking the members, county representatives, and last, but by no means least, you, Mr. Editor, for what you have done to raise the N.R.S. to the positionit now holds. It is my hope that the society's progress will continue C.5a3 unabated, and that the N.R.S. will pass from strength to H FC strength.-LESLIE W. ORTON, " Kingsthorpe," Hawthorn TRANS: Drive, Willowbank, Uxbridge, Middlesex. 6A6 MOD: VALVE RI QUERIES 200Q Answers to any fair problems relating to short-wave radio are offered free to any of our readers; we do GB - not, however, undertake to supply circuits of superhet receivers, etc., but shall be pleased to entertain any E HT+ design queries that do not entailthe drawingof elaborate circuits. 1 have had many discussions as o what the modulation is theoretically. Some tell me itis a modified form of anode All enquiries must be sent with the coupon cut modulation while quite as many say it is only another form of grid modulation, and again a third circle maintain that from page 40 and addressed to " The Editor, The Itis a combination of anode and grid modulation.I leave Short -WaveMagazine,84-86TabernacleStreet, others to settle the theory of it and meantime call it cathode modulation because the modulation is injected into the p.a London, E.C.2." A stamped addressed envelope must valve via thefilament. accompany allcorrespondence.

21 GUIDE TO THE WORLD'S SHORT-WAVE BROADCASTERS (listed by Continent)

Compiled for "The Short -Wave Magazine" by F.A. BEANE (2CUB)

All times are given in G.M.T. for convenience.

LATIN AMERICA

HJ4ABB, MANIZALES (Colombia) HJ4ABD, MEDELLIN(Colombia) Metres :49.10. Kilocycles :6,110. Power :Believed to be 1,000 watts. Metres :51.90 or 48.88. Kilocycles :5,780 or 6,138. Operating schedule : 23.00-04.00 irregular. Power :1,000 watts. Standard time :G.M.T. less 5 hours. Distance from London : Approximately 4,780 miles. Operating schedule :15.00-19.00 and 21 00-- 04 00 daily. Postal address :" Radiodifusora HJ4ABB, Apartado 175, Manizales, Colombia." Standard time :G.M.T. less 5 hours. Identification characteristics : Announces as "Radio Distance from London : Approximately 4,650 miles. Manizales,EstacionHJ4ABB enManizales, Caldas, Colombia "and ofteninEnglishas " Radio Manizales in Manizales, Caldas, Colom- Postal address :" Radioemisora HJ4ABD, La Voz bia, South America."At other times the call Catia, Palacio Municipal, Medellin, Colombia." is abbreviated to " Radio Manizales." Identification characteristics :Employs the slogan Verification of reception reports :Confirms with " La Voz Catia " often. large card bearing red call -letters; difficult tq obtain, however. Verification of reception reports :Sends letter-veri.

HJ4ABC, IBAGUE (Colombia) HJ4ABE, MEDELLIN (Colombia) Metres: 49.26. Kilocycles: 6,090. Power: 1,000 w. Metres: 49.20. Kilocycles: 6,097. Power: 1,000 w. Operatingschedule :Believedtobe 23.00 - Operating schedule :14.30-18.00 and 22.00- 04.00 ;irregular. 04.30 daily. Standard time :G.M.T. less 5 hours. Standard time :G.M.T. less 5 hours. Distance from London : Approximately 4,700 miles. Distance from London : Approximately 4,650 miles. Postal address: " Radiodifusora HJ4ABC, Apartado 39, Ibague, Colombia." Postaladdress :" RadiodifusoraHJ4ABE, Cia. Radiodifusora de Medellin, Medellin, Colombia." Identificationcharacteristics :Referencetothe slogan" Ecosdel Combeima ";fiveorsix Identification characteristics : 4 chimes at fifteen chimes and occasionally the callin English as " HJ4ABC, Echoes of the Combeima, in Ibague, minute intervals; slogan " La Voz de Antioquia"; Colombia, South America." relays HJ4ABK and uses English often. Verification of reception reports :Confirms with Verification of reception reports :Confirms with QSL card. QSL card.

22 HJ4ABH, ARMENIA(Colombia) HJ5ABD, CALI (Colombia) Metres: 31.51. Kilocycles: 9,520. Power: 1,000 w. Metres :49.3. Kilocycles :6,085. Operating schedule :13.00-16.00 and 23.00- Power :Believed to be 1,000 watts. 03.00 daily. Standard time :G.M.T. less 5 hours. Operating schedule :00.00-04.00 daily, except Monday. Distance from London : Approximately 4,780 miles. Postal address :" Radiodifusora HJ4ABH, Aristiz- Standard time :G.M.T. less 5 hours. bal Hogos y Gutierrez,Armenia, Caldas, Colombia." Distance from London : Approximately 4,980 miles. Identification characteristics : Two chimes between announcements; four at fifteen minute intervals; Postal address :" Radiodifusora HJ5ABD, Miguel callin Spanish, and inEnglish as " You are Rivas, Cali, Colombia." listeningto HJ4ABH, the Voice of Armenia, located in Armenia, Caldas, Colombia," or some- Identification characteristics : Employs three times as " Short-wave station HJ4ABH and long - chimes, similar to N.B.C., atfifteen minute wave HJ4ABN, in the City of Armenia, Caldas, intervals coupled to the slogan " La Voz del Colombia, South America."Closes with one- Valle." step-" The Spanish Soldiers." Verification ofreceptionreports :Confirms by Verification of reception reports :Confirms with QSL card. QSL card, but difficult to secure.

HJ4ABP, MEDELLIN(Colombia) HJ7ABD, BUCARAMANGA (Colombia) Metres :31.15. Kilocycles :9,630. Metres: 49.75. Kilocycles: 6,110. Power: 1,000 w. Power :1,000 watts. Operating schedule :not definitely known, but Operating schedule :13.00-04.00 daily. heard from 23.00. Standard time :G.M.T. less 5 hours. Standard time : G.M.T. less 5 hours. Distance from London : Approximately 4,600 miles. Postal address :" Radiodifusora HJ7ABD, Radio Distance from London : Approximately 4,650 miles. Bucaramanga, Bucaramanga, Colombia." Identification characteristics : Announces in Spanish Postal address :" Radiodifusora HJ4ABP, Medellin, as " Radio Bucaramanga, Estacion HJ7ABD en Colombia." Bucaramanga,Colombia, AmericadelSud ", sometimes as " Radio Bucaramanga." English Identificationcharacteristics : Relay HJ4ABQ; used infrequently, the name Bucaramanga being EnglishconcertSundays at04.00;slogan spelt out distinctly; bugle fanfare at the hour; "Emisora Philco "; sometimes uses single chime news bulletinat 00.30; sometimes employs between announcements and generallythree female announcer. Verification of reception reports :Will, no doubt, each quarter-hour. verify as reports are requested. Verification of reception reports :Confirms with N.B.-This may be HJ2ABD, Radio Bucaramanga, QSL card. of the same city, employing a new call -sign for the 31 m. band.

HJ4ABU, PEREIRA (Colombia) HJN, BOGOTA (Colombia) Metres 48.78. Kilocycles :6,150. Power :Believed to be 5 kw. Power :Believed to be 1,000 watts. Metres :50.42. Kilocycles :5,953. Operating schedule :14.30-17.00 and 23.30- Operating schedule : Thought to be 01.00-04.00 03.00 daily. daily. Standard time :G.M.T. less 5 hours. Standard time :G.M.T. less 5 hours. Distance from London : Approximately 4,780 miles Distance from London : Approximately 4,780 miles.

_Postal address :"Radiodifusora HJ4ABU, La Voz de Pereira, Cesar y Mario Arango M., Pereira, Postal address :" Radiodifusora HJN, Ministerio de Caldas, Colombia." Education Nacional, Teatro de Colon No. 528, Bogoto, Colombia." Identification characteristics :Announces often as " La Voz de Pereira, en Pereira, Caldas " and Identification characteristics : Announces in mentions " GeneralElectric " often; does not Spanish as " Radio Nacional " and occasionally appear to employ English. in English as " This is HJN, the National Broad- casting Station in Bogota." Verification of reception reports :Confirms with QSL card. Verification of reception reports : Will not verify.

23 OPERATION ON 1.7mc. Announcing Some Proposed dx Tests By G6F0

TsaT TICE1.7 mc. amateur band is being sadly Discovery neglected by the majority of transmittersgoes with- out saying ; but this has been the fate of the low- However, another and more important fact which frequency bands ever since 1926, when the rush toemerged-and it should be explained here that the get lower and still lower in wavelength first started.schedule ran from midnight till breakfast -time daily It is, however, noteworthy that the largerpro- -was that the peak time for Trans -Atlantic signals portionof those amateurs who are atpresent on 1.7 mc. was from 05.30 to 07.30 G.M.T., while operating on1.7mc.fairlyregularly are "oldit also became evident for other reasons that the timers" who, while they do their shareon the dxseason was not well enough advanced for two-way hands, use 1.7 mc. for local working in daylight working with low power. and medium -distance contacts after dark.In other Accordingly, a further test on the same lines was words, experienced transmitters realise to the fullorganised in February,1933, the same group of the yalue of our 160 -metre band, but it is safe tostations taking part.The writer had the good for- say that the great majority of the younger genera- tune to be first across, working W1DBM one very tion of amateurs-those who have been licensedchilly morning for over an hour between 06.00 and during the last three or four years-rushed straight 07.15 G.M.T., with solid copies both ways.This to 7 mc. for their initial efforts on the air, with the was with 9 -watts input to a push-pull transmitter results which we all deplore to -day. A greatmany from 230 v. d.c. mains, the radiating system being of these newcomers are not even licensed for 1.7a simple type of aerial -counterpoise system with Inc. simply because they made no request for it,two 66 -feet arms, such as could be erected almost and so one of the most useful and interesting ofour anywhere. G5WU was also heard on this occasion, bands is closed to them-which may be justas well ! his transmitting arrangement being almost identical with that described. Retrospection The following year, several other low -power G Recent articles in this magazine stations repeated the feat, and since then a total G2NS have GSGQ of about six British stations have worked the States effectivelydisproved someoftheor Canada on1.7 mc.Of these, G5WU, G2II, accepted objections to a wider use of 1.7mc.-G6YQ and G2PL should be mentioned, and there limited range and b.c.l. interference troubles.But the fact that here it is also being suggested thatare probably others of whom the writer has not even dx is possible needs some further explanation.heard. So let us delve briefly into history, here recorded for the first time. Future tests In the winter season 1931-32, it was noticed by Coming back to the present time, we are now many,in common with the writer,that thoseaproaching the 1938 season, and once again the European amateurs who did appear on 1.7me. question has been raised about organising similar could be worked quite as easily on that bandas on, tests.There are several operators who have already say,7mc. The outstanding example was theindicated their desire to take part; both in the famous OK3SK who, using only 3 watts,worked on States and on this side, and the present :suggestion one particular eveningallthe G stations whois that the tests be arranged for the first or second happened to be on the band.This success en-week in February.Whether any organised effort couraged a small group of keen 1.7 inc. enthusiasts, is made, however, depends on the response to this one of whom was your present scribe, to set aboutarticle, so that readers interested are asked to get organising some Trans -Atlantic tests.At the time,in touch with the writer through this paper.As the idea of this was so ludicrous that itwas kept amuch correspondence is involved, those wishing to close secret from all but the chosen few, and thejoin should write immediately, since we must all test was duly staged in December, 1932, in co-opera-know the call -signs and frequencies which are to be tion with several American stations, the G's being.listened for.Only those who write in answer to of course, tied down to ten watts input-and itthis article will receive the necessary details, while was a genuine 10 watts in all cases.So far as any the results (if any!) will be duly published in these of our signals getting over to the Stateswas con- columns. cerned, the test was a failure, but we did hear For those who may be new either to the 1.7 inc. consistently two or three W's, of whom W1DBMhand or amateur transmission, we would say that will always be remembered. He cameover everysuccess depends on efficiency-even a small radiating morning at anything from R5 to R7, being readable system can be made to perform well-while a QSO right up till 08.00 G.M.T., or broad daylighton thiswith the States on 1.7 me. can be marked down as side. We found afterwards that this was scarcelya really outstanding achievement. to be wondered at, as he was using 460 watts input Finally, it is hoped that there will be in the near and a directional aerial 560 feet long !Moreover, future an opportunity to augment this article with his QRA was Cape Cod, about as near this country some details regarding suitable apparatus and small as he could reasonably get. aerial systems for 1.7 mc. working.

24 Kits or complete instruments as described in" Lowest charges for first class work. 15 years' experience. U.S.W. Equipment. Trans- mitters of allpowers. Specialreceivers and instruments builtto your ownspecification. Service Department for over - hauling, repairing all U.S. andBritish sets. Completely equippedworks 0\\Prompt Service.Free quotations-no obligation.We have helped many thousands of amateurs throughout the world.Let us be of service to you.Send us details of your requirementsto -day. (Tropical finish on all apparatus, if desired)

G. SCOTT -SESSIONS & CO Radio Engineers (Contractors to H.M. Government Departments, etc.. MUSWELL HILL, LONDON, N.10.

HAVE YOU HAD a copy of our latest Catalogue of Short-wave NEW YEAR Components ? Full of 1 id. good lines for short-wave1 RESOLUTIONS ! enthusiasts. 100,tfree If by some chance you have been ploughing a lonely furrow in your experimental work why Q.C.C.H.F. CHOKES not make a New Year's Resolution to join the specifiedfor the Radio Society of Great Britain " IDEAL " RECEIVER. The annual subscription tis moderate (Lon- don 21/-. Provinces 150. Type A. Three required 2/3 each The Society, founded in 1913, to -day has a Type B. Three required 1/3 each membership well in excess of 3,000. Each month the T. dr R. Bulletin is sent post free to members. THE QUARTZ CRYSTAL CO., LTD., This Journal contains on an average 60 pages of up-to-date technical and topical inf, rrnation- 63 & 71 KingstonRd.,New Malden, Surrey, Eng. written by and for radio amateurs.) Telephone No.: MALDEN 0334. The November issue includes important con- tributions dealing with such widely different subjects as Third Harmonic Suppression. a low power battery operated transmitter, The Month on the Air. 28 and 56 Mc. activities. International and local Contests, Bright Ideas, and a full length SPEAK TO THE WORLD article on the construction of Transmitters, the \A ITH AN latter being Part VIII of the popular " Helping Hand" feature. In addition, "Uncle Tom" commences a Transmitting new series of monthly contributions under the R.F.P.15 title -Twelve Years Back." Price - - 30 -PENTODE Resolve to -day to write for a CODY of ibis issue (price11-post free) and ask forfull Filament Volts 4 v Anode Load 10,000 ohms details of membership. Anode Volts 500 v Screen Volts 300 v TwR AUcommunications to Max. Anode Input 25 wattsSpeech Input 1 watt The Secretary : RADIO VALVE Co.Ltd., RSGB RADIO SOCIETY CF GREAT BRITAIN 362 324 6 LIVERPOOL ROAD, 53 VICTORIA ST., LONDON, S.W.1 LONDON, N.7.NORth 1853

2 5 Practical Ultra- Short-Wave Reception Some Notes on Apparatus and Technique By A.J. DEVON

THE INTERESTING ARTICLES which have appeared efficiency at these frequencies will be low, because recently in this magazine on short-wave reception the values of capacity and inductance must be in general, and results on ten metres in particular, chosen to be the best compromise over themore will probably encourage many readers to explorenormal tuning range.Putting this another way, the 7 -10 -metre range.There are several commer-for reception on 40 metres, by-pass and de -coupling cialreceivers which tune down to below sevencondensers should have a value of .001 mfd., but metres, but itiscertainthat the majority ofon 10 metres the corresponding optimum capacities listeners willuse home -constructed apparatus, asare not more than .0003 mfd., and on 5 metres, thecommercialsetsmentioned-beingdesigned .0001 mfd. or less.In other words, it is at present primarily for television reception-will necessarily be a practical impossibility to design a short-wave in the hands of comparatively few people, whoreceiver which will give level performanceover a happen to be within range of Alexandra Palace. wave -range 10-200 metres, or even 20-100 metres, The purpose of this article is therefore to discuss, though in the latter case the discrepancies at each for the benefit of the more technically -minded home- end of the range will naturally not be constructor who wishes toget away from the so great. ordinary type of short-wave listening, some of the That this question of values isvery important is practical points in connection with the design andshown by consideringthe frequenciesinvolved. operationofreceiverscoveringthe range5-10 The frequency at 40 metres is 7,500 kc., at 10metres metres. it is 30,000 kc., and at 5 metres 60,000 kc.That is, dropping the wavelength 30 metres from 40to 10 Compromise unsatisfactory metres corresponds to a frequency change of 22,500 kc.But the change in frequency when tuning from First, as regards 10 metres-an existing short- 10 to 5 metres only is 30,000 kc.Obviously, there- wave receiver can very often be adapted to givefore, when working on the range 5-10 metres, satisfactory results on this band, but they will never we be as good as with a set designed for the purpose.are not only dealing with a part of the radio spec- The reason for this is that practically every pub- trum where frequencies are very high, but the rate of change of frequency for small differences inwave- lished design for home -constructed short-wavere- length is also extremely rapid. ceivers assumes their use over a waveband of about Further, the ques- 15 to 70 metres, as it is within this range that thetion of design must also be a compromise, forin- ductance -capacity ratios suitable for 10 metresare more regular and reliable transmissions fall, andnot the best for 5, though here the discrepancy is even if the set will tune down to 7 metres, itsnot nearly so marked as when trying touse on the

C1-4-5, .00005 mfd. C2 -C3- C9,.0002mfd., C6- .000025 mfd. I Eddystone 900 20 ), C7-.0001 mfd. I Eddystone 900 100) . R I -R6, 10,000 ohm 1 -watt. R2, 40,000 ohm cf 1 - watt. R3,50,000ohm1 -watt. R4, 4 megohm1 -watt.R5, 50,000 ohm 3 -watt potentio- meter. V1-2, Hivac SC220SW. Fixed condensersshould be J mica. See table for RFC and L1- L2. X goes to LT pos. Variable condensers should be mounted onadjustablebrackets,using Eddystoneextensioncontrols, slow-motion drives and flexible couplers. FIG. 1. 26 latter band a short-wavereceiver intendedfor across the rotor terminals of C6 and C7, i.e., the optimum performance on the medium short-waverotor of C6 has two coil ends brought to it, so that range. there are three terminals to be unscrewed when In practice, the best thing to do if serious experi-changing coils.The stator of C7 goes straight to mental work is contemplated between 5 and 10the plate of the valve.The supporting arms of metres is to build a separate receiver for this range,the coils should be bent so that the two coils are using it as a radio -frequency stage for an existingin the same line and about a -inch apart, making l.f. amplifier, which may be the audio side of thesure that their turns are in the same direction. ordinary set.While there is a lot of interesting The operation of the receiver isquite simple. work to be done on s.w. superhets, any ultra short-With C6 set near full capacity and C7 about half - wave signals which are reaching the aerial will bemesh, the potentiometer R5 is adjusted till oscilla- heard on headphones quite as easily as on a biggertion occurs.The control of reaction now takes receiver operating a speaker, so that the listenerplace on C7, R5 only being touched when changing on the highest frequencies need never feel himselfbands, as re -setting will be necessary with different at a disadvantage because he is only using a straight tuning -ranges. circuit. Design considerations It scarcely need be said that everything must be kept as low -loss as possible when designing such a receiver, a suitable circuit for the radio frequency end of which (h.f. stage and detector) is given at fig. 1, and a good practical lay -out in fig. 2.Either irjetm_2_1_, the usual type of l.f. amplifier can be built on to

the receiver, or the output stage of any existing set i used, as suggested previously. The circuit itself is quite conventional, points to /0 notice being the use of an h.f. stage and a screen - C6 grid detector valve.The former is merely to isolate C--0 the detector from the aerial, obviating the effects of aerial damping and "blind spotting" as well as allowing any end -on type of aerial to be used.The Foe e values are important, and as regards valves, the Hivac SG220SW are strongly recommended.These have the grid connection at the top, which results in greatly improved efficiency on the high frequen- cies and facilitates a low -loss lay -out with short leads.The three r.f. chokes and the coils are very easily home-made, the necessary data being given in the table.The variable condensers must be on extension controls, and the Eddystone catalogue A- will suggest suitable parts and slow-motion drives, those actually recommended being shown in the circuit caption.Existing components can of course be used provided they are of good low -loss design and of the correct values, but the general lay -out indicated in fig. 2 will probably have to be altered Sx to suit them. As shown in the sketch, a wooden baseboard and panel should be employed, as on the very high frequenciesmetalchassisarenotsatisfactory. Losses and coupling effects are introduced, and very often a receiver which is quite stable and FIG. 2. easily handled when assembled on a wooden base- As this is suggested as an experimental receiver board with an ebonite or wood panel, becomesfor general exploration of the ultra short -waves, almost uncontrollable when built on an identicalband -spread is not included, though it is a simple metal chassis. matter to incorporate a three -plate midget variable The coils LI and L2 are all made self-supportingin parallel with C6 in order to get it.Tuning is, and are mounted directly on the condensers. They of course, quite sharp, but not unduly so as C6 is are wound up on a -inch diam. formers and then,kept small on purpose. slipped off, have their turns slightly spaced. Enough wire should be left to allow the coils to mount with Locating the Bands their axes horizontal-the Eddystone variable con- The 10 -metre band will readily be found by densers have their rotor and stator terminals atlistening almost any afternoon, when many Ameri- different levels-and the endsof the supportingcan amateur 'phone and c.w. stations will be heard leads should be looped to go under these terminals. at good strength.For reasons connected with the This form ofmounting admittedly makes coil -harmonic relation of the amateur bands and the changing not the simple matter it is with plug-inconvenience of using lower frequency crystals which formers, but thisis more than counter -balancedgive transmitting points on several of them, only by the gain in efficiency, as all unnecessary leadsabout half the 10 -metre band is populated.That are cut out.It should be noted that while LI isis to say, though the band of frequencies reserved mounted directly across the terminals of C6, L2 isfor amateur transmission is 2,000 Ice. wide, from

27 28,000 to 30,000 kc., the bulk of the signals will be GUERNSEY BRANCH I.S.W.C. VISIT heard between 28,000 and 29,000 kc., so that bear- ingthisin mind, a roughcalibrationcan be FORT GEORGE obtained. Members of the Guernsey Chapter of the Inter- As regards 5 metres, it is not possible to say, for national Short -Wave Club were permitted, by per- certain when or if signals will be heard, unless themission of the engineer -in -chief, to visit the Post listener has an amateur transmitter living withinOffice ultra short-wave radio -telephone station at 10 or 15 miles of him who operates on 5 metres. Fort George, Guernsey. The difficulty with this band is to find it, as even Telephone communication between Guernsey and with careful specification and exact reproduction ofthe mainland is given by one submarine cable and coils, etc., it is always a matter of chance if thefour radio circuits.The radio circuits are provided band is located at the first attempt. by the use of two sets of carrier equipment operat- However,thereare two ways in which theing on two radio links working on approximately 5 - receiver can be calibrated for 5 metres.Cut aand8 -metrewavelengthsrespectively.By this length of wire to 81 feet and loop one end looselymeans two simultaneousconversations may be near to, but not touching, Ll ;the other end istransmitted from each radio transmitter and re- left free and hung up to the picture -rail or anyceived on each radio receiver. other convenient point.Now tune with the re- The transmitters are provided with quartz crystal ceiver oscillating.If a setting is found on C6 atcontrol to ensure stability and to eliminate the which the detector tends to go out of oscillation,necessity for retuning frequently.The actual power or cuts off completely, the receiver is then veryradiated from the aerial system is of the order of near 5 metres, as eight feet of wire is resonant 100 watts in each case.The two speech circuits at that wavelength,i.e.,ittunesto5 metreswhich are to be combined in each transmitter pass approximately by virtue of its physical dimensions. from the landlines through what is termed the diplex The exact resonance point depends on the capacityequipment.Here the two bands of speech fre- of this wire to ground and other similar factors, soquencies are combined and "scrambled" to provide that it is only an indication and no more, but ifsecrecy and the resulting band of frequenciesis the cut-off effect comes near the middle of thethen applied to the transmitter in the normal way. tuning range, it can safely be assumed that part at least of the 5 -metre band is being covered.Con- versely, the spacing of the turns of L1 should be adjusted so that the "hole" in the oscillation is brought to the mid -way setting of C6. The second method is to bend 17 inches of No. 12 bare copper wire into a loop and connect the ends across a .000025 mfd. variable condenser, fitted with a scale, preferably slow-motion.The whole thing forms an absorption wavemeter, which will bring the middle of the 5 -metre band somewhere near 80 degrees of an 0-100 degree dial.It is used in much the same way as the length of resonant wire-the loop of the wavemeter is held near LI with its dial set to 60 degrees, and C6 is then varied with the detector oscillating till a "plop" is heard, indicating that the two circuits are intune.If signals ofThis procedure is adopted in order to render the known frequency are eventually heard on 5 metres, messages unintelligible to persons who may try to the wavemeter can be accurately calibrated by the intercept them by "tuning in" to the radio trans- reverse process, and a graph drawn.Note that mitter. when using such a wavemeter, it should be mounted Superheterodyne type receiversare employed, on a piece of wood to minimise body -capacity effects. having crystal control to ensure stability of tune, In many parts of the country there is considerableas in the case of the transmitters.The output from amateur activity on this band, so that there is no the receivers is passed through an equipment of reason why something should not be received.The filters and demodulators which separate the two co-operation of listeners is gratefully acknowledged conversations and restores the frequencies of which by amateur transmitters, and there is much useful they are comprised to the positions they occupied and interesting work to be done, in which listeners before being "scrambled" at the radio transmitter. can play an important part. They are then passed out over the landline circuits to the terminal trunk exchanges.The aerial sys- COIL TABLE tems usedconsistofarraysdesignedto have strongly directional characteristics to and from the Ll.L2. distant radio station. 7-10.5 in. ... 8 5 The radio station in Guernsey is situated at Fort 4.5-7.5 m. ...4 3 George, while that on the mainland is on the cliffs All coils i-inch diam., self-supporting, using No. 16near Chaldon, some few miles west of Lulworth bare copper wire with turns slightly spaced.Wave- Cove.The landline terminations of the circuitsare length can be adjusted by squeezing in or openingin St.Peter -Port and London respectively. To out turns. facilitate the routing of calls two of the circuitsare CHOKE TABLE normally extended over a submarine cable link to RFC1 Jersey, providing two direct London -Jersey trunks. 30 turns No. 24 enamelled on 4 -inch wood The accompanying photograph shows themem- or ebonite former, turns slightly spaced. bers of the Guernsey Club at the foot ofone of the RFC2 20 turns as above. 100 -feet masts supporting the imposing array of RFC3 40 turns as above. 5 -metre aerials.

28 occupied the next shelf, the p.a. the next and the AROUND THE HAM SHACKS antenna tuning gear the top.Good quality short- wave components were used this time.The tx was operated c.o.-p.a. on 7 mc. and c.o.-f.d. on 14 mc. 3-G2UK Many pleasant QSO's were had and some dx A. C. Gee tells the story worked. of a transmitter that Though this tx worked very well several weak won for him two trophies points soon showed up.Rack and panel construc- tion is all MY FIRST experience of amateur radio came when, rightifthe during the winter of 1934, I built a short-wave rigisto be receiver and started to hear the telephone trans-more or less missions of some of the local amateurs.It was pennon e n t, not long before I began to wish I could participatebut where in experimental work, so application was made forminor chang- a transmitting licence and after the usual delays, esarecon- my amateur call was issued in February, 1936. stantly being Since then the station G2UK has undergone amade, either gradualandprogressivechange. Experimental the panel work has always appealed to the writer so it is notgets shot full surprising that a number of transmitters have beenof holes or it built and subsequently pulled to bits again, duringhas to be con- the short time I have been licensed. stantlyr e - Most station descriptions seem to be written byplaced, which an outsider : a fellow ham who comes into the shack becomes ex- one fine day when dx is good, takes a fancy to thepensive. Also gear and "writes it up."The result is a faithful- the shelves we hope-description of the gear, but it gives no were found to indication of what really makes an amateur station : be too small the failures and minor troubles which have ulti- and coupling mately been overcome and resulted in the construc- arrangements tion of gear which is reliable and can be depended between on to make the best of conditions on the air. different stages were FirstEffort Failure longer than The first tx at G2UK was one of these failures.desirable. The Looking back I always feel glad it was a failure, as power.pack the lessons learned in getting it to work have stood was too small me in good stead ever since.The chief troubleanditwas was that most of the components had come out ofobvious that two packs giving different voltages the junk box and were not suitable for short-wave would be much more convenient than only one where work.That tx was a simple c.o.-p.a., built bread-the voltages for the c.o. and f.d. had to be obtained board fashion, with the power pack located rathervia dropping resistance. artistically but very inconveniently beneath.The So with these points in mind a scheme for a new tuning condensers were from an old b.c.l. set, thetx was got out.The design was also somewhat coils were wound on formers of a very doubtfulinfluenced by the fact that the local radio society's material, and what h.f. was not lost by it wasexhibition was in the offing. effectively by-passed via some h.f. "chokes" which, So in this manner the present tx at G2UK came though reputed to be for short-wave work, mustinto being.The frame is of one -inch angle iron and have been designed for long -wave sets ! takes the form of an open rack.It is three feet, The combined efforts of the "local gang" did getsix inches high and eighteen inches wide and deep. it working eventually, but the results were nothingA series of holes were drilled up either side so that to be proud of.However,it provided the first struts to carry the rack can be fixed where required. thrill of being on the air, and the excitement ofSimilarly, these struts are drilled to accommodate receiving the first batch of QSL's over, attentionracks of differing widths.The base contains two was turned to building something more worthy ofpower packs, each giving 500 volts at 250 ma., from the traditions of amateur radio. type 83 mercury vapour rectifiers.There are also several filament transformers giving various voltages. A Special Endeavour The only switch provided is an ironclad mains The next tx was built rack and panel fashion. switchboard type.This is operated by the hand - The rack was built of wood and was forty incheswheel on the front of the transmitter, and turns high, taking panels twelve inches wide.The power on the power to the whole transmitter.The h.t. pack was located at the bottom and was quite is remote controlled by a relay situated on the first accessible for replacing blown fuses, etc.The c.o. shelf, this unit also accommodates the keying relay.

29 Both these relays are operated by a metal rectifier included in the unit.A small aluminium cabinet is NATIONAL RADIO SOCIETY also on this rack in which the bias batteries are housed.Above this is the c.o., stage coupled to Reorganisation Commenced the f.d. stage via a .0005 fixed condenser. The Present Line-up By F. C. BIGGS (Hon. Sec. pro tern) A built-in meter iswired permanently in the I have been invited to act as temporary secretary anode circuit of the c.o., so that one can see at a owing to the resignation of Mr. Leslie W. Orton, glance how the crystal is behavingitself.Both who, since the formation of this Society has held these circuits are the usual triode type of oscillatorthe position of honorary secretary and treasurer.I have accepted and already plans are being made and doubler circuits respectively, the valves usedto provide for reorganisation, in which you, as a being a LS5 and an LS5B. The p.a. stage is onmember, are invited to co-operate. the top rack and is link coupled to the f.d. stage. You will agree it is impossible for me to give much Closed circuit jacks in anode circuits of f.d. anddetail here, consequently I append a copy of the p.a. allow currents in these circuits to be read with letter sent to all County Representatives during the a multi -range test meter.Keying is in the f.d. week -end November 27.This letter will explain the anode circuit, a plug from the keying relay beingimmediate plans. A notification of an Executive Meeting to be held on November 29 has also been inserted in the jack in the anode circuit.A T25D sent, and by the time these notes appear the first is used as p.a. Executive Meeting will have settled our temporary The units are built on oiled oak baseboards which policy.Here is the letter cent to Representatives : fit into polished aluminium racks, and allcon- "DEAR SIR, densers and components are mounted on stand-off "Mr. Leslie W. Orton has resigned the duties insulators.H.T.isfed through from below via of Honorary Secretary and Treasurer of the above busbars of 4 -inch copper rod and "feed -through" Society-I understand he has informed you of this insulators, ono power pack supplying the c.o. and fact.In view of this development I was invited f.d. and the other feeding the p.a.The frame was to act as Honorary Secretary until such time as sprayed B.B.C. grey and when finished presented a the members have had an opportunity of ex- very pleasing appearance. pressing their wishes.I have pleasure in accept- It need hardly be said ing this trust and shall endeavour to carry out the that the writer felt amply rewarded for the time duty in a manner acceptable to all with a view spent on the job, when the transmitter was awarded to re -organisation of the Society. the Southend and District Radio Society's Challenge "A temporary Committee has been formed and Cup in the early part of this summer as well as first consists of the following County Representatives prize in the Transmitter Section. residing in or near London :Messrs. S. G. Berry, F. Chapman, E. W. J. Field, G. J. Goldsworthy (Treasurer, pro tern), R. Pearce, E. J. Sprange H.Q. activities R. S. Stevens, F. Stringer and R. C. Taylor.This All Southern services are suspended temporarily. Committee will form the machinery for receiving Please note the South telephone service is inopera- and acting upon your proposals with regard to the tive, but that of the North is continuing as before. Calling of an extraordinary general meeting to Details have appeared in earlier issues of this maga- appoint Officers and an Executive Committee. zine. "Your suggestions regarding the future policy of I.F.S. meetings are held at 18, St. David's Ter- N.R.S., proposed Rules, and any other relevant race, N.C.R., Dublin every Wednesday as 8 p.m. matters will receive the attention of this tempo- Morse classes are held.Mr. J. C. White, the I.F.S. rary Committee, which will then hand its report Representative, will be pleased to supply theoretical to the elected Secretary for submission to the circuit diagrams of straight receivers to members on elected Committee. receipt of a stamped address envelope --phase note "To further assist, will you please forward to me that Irish Free State stamps will be accepted-but a nominal roll of District Representatives and do not fix to envelope.The Irish postal rate is 2d. Members you are in touch with, giving name, address and joining date, also whether they are News Sheet Services Honorary or Full Members. There are two services at the moment :Lancs. "Assuring you of my close co-operation, I am, Branch, Mr. A. Park, 14, Fairfax Road, Prestwich, Yours sincerely, C. F. BIGGS, Hon. Sec., pro tern." Manchester, a very interesting one indeed, and can be had post paid for 12 months by sending is. P.O. Suggestions will be appreciated to .Mr. Parks ; and the second, Essex Branch, Mr. R. S. Stevens, 43, Pettits Lane, Romford, Essex, I welcome suggestions towards a method of giving which by the way is for Essex members only ;this memberstheopportunityofexpressingtheir is also an interesting News Sheet. opinions, and suggest they get in touch with their The competition is suspended pending the decisionnearest County Representative, who will forward of the Committee, as also is the Magazine Service. the collected information to the Executive Com- Finally, I would ask your indulgence this monthmittee.The next step will be a ballot of members for the necessary scrappy notes, and next monthfor the election of officers and an Executive Com- I hope to be in a position to tell you the outcomemittee.Please assist in this direction by at least of committee deliberations, then we can get down sending your membership card in-you will receive to a settled period of development. a new one as soon as design, etc., has been fully Please address your H.Q. enquiries toC.F. gone into.Membership remains as before-ls. Biggs, 87, Lordship Lane, Tottenham, N.17. (Continued at foot of previous column.)

30 PRIVATE ADVERTISEMENTS 2d. per word. Minimum 2s.

Readers replyingto private advertise- ments are requested to enclose stamped addressed envelope for return of remittance or notice of disposal.Replies to box num ber advertisements should be addressed to Box , " The Short-Wave Magazine," 84, Tabernacle Street, London, E.C.2. Box number advertisements are subject to an additional charge of sixpence. The Advertising DePartment is willing to assist in the exchange of goods against cash where invited and agreed to by both par- ties.

RAYTHEON 6D6's.Practically unused. Only three, 3s. 6d. each.G.P.O. Morse key, 5s.-Box 1.

TRICKLE CHARGER (Westinghouse rec- tifier), 6 volt 1 amp. and complete in case with ammeter, £2.Hivac QP240, unused, 8s.-14, Carolina Road, Thornton Heath, Surrey.

READERS' BARGAINS This new featureis introduced at the request of a number of readers. Watch the column carefully and useitto buy and sell your gear.

WANTED.-Moving coil voltmeter, range 0-2,500.-Box 2.

BATTERY or A.C. CONVERTER, 13 to 70 metres (New), sell for 35s.,!ist 63s.- Box 3.

FOR SALE.-Eddystone 1935Kilodyne Four, Short -Wave Battery Model in cabi- CONTACTS FOR CHRISTMAS net, with six coils covering 121-500 metres Don't be short of a spare 5 amp Plug, a Loudspeaker Control, without a break.Less batteries and loud- Panel Strips, Fuse Plugs, Terminals, Plugs, Sockets, or even a speaker.Valves probably 25% off emis- Valveholder, you are almost sure to want one or more during sion.What offers ?-M.A.W., 98, Welling- the Festive Season. ton Avenue, Westcliff-on-Sea. ALL GOOD DEALERS STOCK CLIX Descriptive Fo'ders " S.M " Free. CRYSTALS -1.7 and 3.5-for Sale, s each.-Radio G6MY, Morley, Leeds. n BRITISH MECHANI UCTION AC12 EKCO ELIMINATOR. Exchange 79a ROCHESTER ROW for anything Radio.-Box 4. LONDON - S.W.1

31 LISTENERS' DX CORNER

By The DX Scribe

AN ALL-ROUND MONTH of dx this time.10, 20, 40, Another thing about tenisthe aerial.Some and 80 all alive,so we only want trans -Atlantic people swear by long aerials, others will use nothing signals on 5 and 160 to complete all bands. 160 but doublets.I've got several aerials up, including may wake 3.qa any time now, so it is worth lookinga 40 -metre and a 20 -metre doublet, but I thought on this band-m the early mornings just in case some- I'd try some indoor aerials.The shack is only thing does come through. about twelve feet square, so I ran lengths of 30 Some time ago both 10 and 160 came throughs.w.g. in various directions across the room. On together.The first intimation I had of unusual South Africans especially a noticeable improvement conditions was searching round on the broadcast resulted, and six feet of wire in the correct direction band one night about 9.30, and listening to Scottish gave better signals than any of the big outside ones. Nationalforalittlewhile.Gradually he wasWith such a small aerial you tan grab the free end swamped out by another station, which proved toand walk round the room until the best direction is be WITC, Hartford, Conn. !Almost as strong asfound.Crude, but effective. the local at 10 p.m.This was one November, and for a few days signals on all bands romped through, Twenty ten coming to life for just those few days. Pacific Coast Americans have again been the main So many listeners find twenty dead and switchfeature of this band.It must have been a record off.It is well worth while trying some of the otheryear for them.Not only have they been coming bands, especially 80.In the early mornings 80 isthrough in the early mornings, but also through the simply alive with signals, and although it has beenlate afternoons and early evenings.Conditions dur- rather a poor band for the past few years, it ising the afternoon have been most peculiar,every W gradually improving, and will probably be produc-district coming through.Listening the other after- tive of some good dx this winter. noon, the first station heard was a VE4, followed Back in 1926 80 used to be the best band, with by W5, VE3, W6, W7, and the rest of the W dis- all continents coming through in a most regulartricts.From 20.00onwardsthingshave been way.40 was rather inferior, and 20 hopeless aftervariable,sometimesverygood,oftencomplete dark.A few people were using the old 8 -metre fade-out. band, but only local contacts resulted.We have been passing through a cycle since then, and now L. LEVITT (LEEDS), starts the ball rolling this 40 and 80 are returning to the 1926 condition.Lastmonth with his comments on the periods October winter, during the vast floods in U.S.A. some inter- 17-18, and November 2-3. esting traffic to and from the flood areas was to be October 17- heard for the seeking, and this season signals should 14 mc.10.20ESSD, LY1CC, LA1G, and many be even better. F8's R9. 10.45G's began to come in. Ten metres 11.00 OZ5BW, TF3P, W2 and 3. Changes in the American 'Phone Regulations have 11.30W8, VE1. coilfused many ten -metre fans.The band extends 12.00 VK2APO, VK3AL at R3 to R4 from 28 to 30 mc., and up to September 17 'phone with W6's R4-5. operation was allowed from 28-29 mc. Both c.w. 28 mc.14.00W2's and 4's, VU2ON. and 'phone was allowed in this band, and it was 16.30WI, 2, 4, 6, 8, VE2, FA3JY. found that most stations congregated on the 28 mc.October 18- end, making QRM appalling.From September 17 14 mc.09.30All locals. the regulations were amended to permit 'phone 11.30W8's, few G's. between 28.5 and 30 inc., the band 28-28.5 mc. 28 mc.Good, but usual dx on 14 mc. from 07.00; being for c.w. exclusively. 10.00 missing. Ten metres has again been the star band of theNovember 2- month.Signals fromallcontinents have been rocking in,except from VK. VK's have been 14 mc.07.10W6, W8, VK. coming through, but few of them are using 'phone, November 3- so are overlooked by many of us. 14 mc.12.00WI, 2, 3, 8, YV4AF, CO7HF. K6 is a newcomer this month, K6MBT being 12.30 W4, 5, CO7AT, 7PA, 7CX& reported by L. Levitt.Maybe more K6's will be 28 mc.18.00-19.30All W except 7, VE1 and 2, heard from now onwards. ZE1JR. Fog has been plentiful this month, so we have Many thanks for this very fb report, om. Noth- had plenty of chances of noticing its effect on sig-ing- unusual seems to have occurred save for early nals.Personally I cannot decide whether it im-morning fade out, and the presence of the Central proves or spoilsthem.Some days the gradualAmericans around midday.Of course W5 is rare appearance of fog has resulted in fade -cut, otherat this time of day, so probably there is some rela- days it has changed bad conditions to good.But tionship between the two sets of stations. W5 is one thing I am certain about is that it increases the more usual around midnight and early morning, and racket from cars, always bad at this QRA. RainI have never heard them between 11.00 and 15.00 also seems to have the same effect. G.M.T.

32 First report from W. PETERS gives fine log on prefers speaker reception to headphones, and as he 3.5, 14 and 28 inc.Pity he has missed W'7 for all can use either at will, is in a position to judge. districts on ten, but he makes up for this with his H. SUGDEN, BRADFORD, has also noticed the 80 -metre log. "group" effect."I find that conditions favour one Commenting on conditions he says : "On 20 con- district perhaps for a day or two, and another dis- ditions have been average, although I have nottrict the next.W5, 6,'7 and 9 do not come in noticed any outstanding days.On Sunday, October together, but generally have their own special con- 31, between 09.30 and sunset, remarkably short skip ditions. On September 14 K7FBE was received prevailed on 20 metres, G, GW, GM, GI, EI, F andabout 07.40, up to that time the band was dead. PA signals coming in more like 40.No dx at all On September 27 he was heard at 07.35, preceded was heard during this period.Another feature hasby K6NSQ at 07.23, K6OQE at 07.25, K6GCT at been the return of W's on the 80 -metre band.In 07.30, and followed by K6BNR." the early hours of Monday, November 8, I logged 8, and would have logged more but my detector fila- Thanks for the dope, om.It seems that this ment gave out (perhaps it felt my excitement!).""group" effect is fairly general.Perhaps we shall A rare "catch" was VElEE working portable at be able to notice some regular cycle, and predict dx the Montreal Radio Exhibition. a few days in advance from it. N. J. RUTTER, SWINDON, apart from an "All - Lastly, from BOB EVERARD, our most con- Continent" log sends an account of his receiver sistent dx'er, comes a list of W6 'phone veri's arrangements.Unfortunately there is not room this received.100 of them, all real dx. month to show the diagram, so I will just say that Bob has very kindly taken the trouble to com- he uses a two -valve receiver for s.w. headphonepile a list of them together with notes on their fre- work, but for speaker reception he switches thequencies, cards. etc.,so that the rest of us will outnut to the 1.f. amplifier of a b.c. set.However. know where to look for them. Many thanks to you I will show this scheme in full next month, so don't from us all for your trouble, om. inundate him with letters asking for details !He Here is the list :

BOB EVERARD'S 100 W6's NEVADA CIF, 14mc, 300w. A real comic OSL. ITH,Lime.300w. Famous Reg Tilt. BIC. lime,130w. CIN, 14mc. " Radio Bug " OSL. betts. FB double photo QSL. FUO, 14,224ke, 85w. Fine 081, in black CUR, 14mc, 250w. IXJ, lime, 50w. FR OSL, red and whit,. and orange on white. CLS, 14,152kc, 500w. Fine QSI., silver, on black. blue, red, etc. JP, lime, 475w. UTAH CNA, 1.4me. JPW, 14mc. COG, lime. JXI, 14mc, 300w. G BO, 28me, 75w. His first C report. CQK, 14,158kc, 200w.First C report. JZE, 14mc, Ow. First C.report. EZD. lime, 215w. CZ, lime. " Aeroplane Contact " OSI.. MIL 14mc, lkw. DEP, 14me. lkw. KMO, 14mc, 180w. First G report. ARIZONA DI KQQ, lime, 500w-lkw. FB playing caul 28mc, 55w. A beautiful coloured DMN, lime, 150w. Comic " Dentist " and photo type. view OSL. QSL. KW, lime, 365w. DKU, lime, 130w. DTE, 1.4me. 1..4J, lime, 250w. Comic()Si,. GZU, lime, 180w. DWE, 14mc, 150w. FB ship OSI.. photo QSL. K SO,I imc, 700w. Fit photo 051,. DVH, 14mc, 500w. LDB, lime, 700w. First G report. DZH,lime.Californianstationof LFIT, 14mc, 300w. CALIFORNIA W1CCZ. LHF, lime, 500w. First C report.Fit CKR, 28mc, 250w. FB Eagle, etc., 0S1,. EIP, lime, 250w. Unique comic "Globe" LIP, 14,174ke, 208w. ERT, 28mc. FB photo, etc., 0S1,. QSL. LK(:), lime. 1,WN, 28mc, 200w. First G report. ELR, 14mc,120w. LLQ, 14mc, lkw. MAF, 28mc, 75w. ROA, lime. Home-made ()SI,. I,LU, lime, I65w. FB photo OSI.. MOV, 28mc. ESX, lime, 300w. I,R, lime, 800w. FB blue and silver MWK, 28mc, 150w. FB photo QSL. FGU, 14mc, 400w. FB photo 051,. QSL. NLS, 28,800ke, 425w. PM, lime. 14mc, 275w. " Mission " type blue NWQ, 28mc. FB " Mission " type 08L. FOY, 14,162ke, 200w. Comic " Dentist " and green. KKW, 30.1mc, 100w. Will soon move to QSL. First Europe report. LYP, lime. FR photo OSL. new location and 200w. power. Fitj,lime, 170w. MBE, lime, 450w. KG, 25,950ke, 100w. GAL, lime, 140w. MGB, lime, 200w. AH, lime. GAT, lime. " Gat " type 051,. MR, 14mc, lkw. FR OSI, in red, etc., AM, lime. Famous Don C.Wallace. GCT, 14mc, 750w. on silver. ANU, lime, 150w. GCX, lime, Owl type QS!, in blue, etc. MWD, Hine. ATO. lime, 400w. GYO, 200w. MRD, lime, 300w. RHO, lime, 120w. HAA, lime. 160w. MXW, 14mc, 70w.1-13 photo QSL. BJB, lime, 200w. HAR, 14mc. MYO, lime, 200w. First G report. BJI, lime, 150w. First G report and Fit NLP, lime, 200w. photo OSL. NNR, 14mc, 300w. BEY, lime, 550w. HEG. OCH, lime. BOS, lime, 500w. Futurist 051.. HJI.J. FB photo QSL, and being re- PN, lime. F13 coloured view QSL. BQY, lime. FB photo QSL. broadcast from 160m. RX, 14me. BYW, lime, 500w. First G report. HOW, 14mc, 700w. FB eagle, etc., OSL. SI, lime, 350w. CAN, lime, 50w. FB photo QSL. ISM lime. Largest W6 OSI, I've seen. UT, 14,216ke, 400w. CC, lime. (P% ins. x 5,4ins.) VU, lime. College QSI,. Condx-Wx Expeditions The log sheets have been sent, to those who applied Freshnewsfrom ARRLadvisesthatthe for them ("DX Corner," November). MacGregor Arctic Expedition, WAWG, on 12,460 This scheme has only just started, so itis tookc. is working W3QP Monday -Thursday at 23.30 early for any results yet.As soon as some of the G.M.T. data received has been summarised detailswill OX2QY, Etah,Greenland,isusingthecall appear here, so please try to spare a few minutes W1XAB for N.B.C. programmes.Another chance during the week to help. to get that rare W1 veri.

33 AK, EG, KL, 7.,Y, RA, 7CX, VP, 8JB, RC. CX2AK, 3BA. Shack Photo ITC 1FG, JB, JW. HH2B, SPA. HI5X, 7G. HK3JA. K4DDII, ENY, SA. I,ULHI, EX, SAN, CZ, 7AG, 8AB, 9BV. NY2AE. The photo this month comes from BILL CROFT, OA4AI, I. N. PY1AH, RA, FR, MK, 2AC, AL, DN, FT, BRISTOL, and shows some of his 190 veri's from 48 GC, JN, 4BI, TAO, 01. TI1AF, 2AV, FG, OFR, RC. VP3BG, countries. A neW one heard the other day was 5PZ, 67R, 6YB. YVSAG. ZP2AC. KA.IME. PK4DG. VS2AK. VQIAB, Fanning Island, in the Pacific.Fb going. K6K1IB, NZQ, OQE. VK 2ABE, AP, AZ, CI, HF, NY, OR, He says conditions on 20 have been simply grand, RJ, TC, TR, VB, VV, XS, XU, 3AL, EG, KI; KR, KX, and his log proves it. MR, PE, PL, WA, XJ, ZL ZZ, 4KO, WU, 5AI, AW, GS. H. SUGDEN, 15, Arncliffe Terrace, Legrams Lane, Bradford. W 7FQK, 6ITIT, EJC, FTU, DEP, NNR, GCT, CQI, MLG, AM, Al,, NTX, LLQ, FJK, BAW, BPM, CUU, BFC, IZI1, IFS, 5YF, ZS, F,CL, BCU, AFG, EHM, DNV, DAN, PHI, FICV, BTU,JC, EBP. VE 9HF, 5G141, JK, 3E0, LI 2CA, IIE, BG, AA, NI, KO, BO, ILR, DX, CA, GR, BR, BP, EX, CF. VO 6I JO, 2Z, II, J. VK3 KX, PE, ZZ, Bc, 2XU, EG. VP6 YB, TR. VS2AK. I'KIZZ. ZT2G. ZS3F. CX2AV. TI2RE, PG, AV, KP. LU9BV, 811R, AB, 7AG, 5CZ, AN, 4B1,, KA. 1111, QA. l'Y 1FR, GO, 2PF, 5AM, AQ. C08 MA, JK, EC, 6011, 2EG, WZ, JJ, RA, HY, 7VP. CF,3 CO, DW, AW, Al. HI 71, W. 11K 3JA, 4AG. IIH2B. FB8AH. ZETJA, ZBIL. YV5 AA, AK. XE 1GK, IV, 2FC, 3AR. K 7FBE, ONZQ, NIXM, IiNIt, OQE, 4ENY, DDII, F,JF, UG. KA1ME. W. PETERS, 82, Salisbury Road, Barnet, Herts. 10 metres.. WI AAK, ADM, ADR, ALT, BGT, EJE, BLR, BOO, COO, COS, DJK, DPJ, PVC, IIVS, IKX. W2 DXT, FBO, PGL, REM, ITCH, JAB, JKQ, KHR, KJY. W3 AIR, BGR, CBT, CKT, GI, GSV, GVZ. BYY, EC, EDD, EEV, EPA, ETF, FT. W5 EHM, CCU, VV, ZA. W6 AK, HX, NILS. W8 BDS, BLP, CPU, CLS, EBS, KYY, MDH, MWI, OUT,. W9 BHT, BMX, CJI CLQ, FAA, TIO, TFV, WMD. G5 AU, KIT, SA. CA AG, CL, GO, KO, 1,1 WU. F3IIM, 8I,X. VE 2KC, 3ANF. 1117G. SP1HII. 20 metres. Co6O9I. CT2AB. SPIDC. VETEF, (Portable in connection with the Montreal Radio Exhibition). VE2BG. VO6D. SU1SG. W5BVNI. XEIKE. 80 metres. W 1AVG, 2AU, JP, GEE, 3c7',BJ, 4DGK, 8G111 01,. HAROLD TAYLOR, Eardisley, Cefn Glas, Penyfai, Bridgend, Glam.22/9/37 to 13/11/37. By the way, many SWL's like to have a photo 20 metres. of their shack on their cards, so if you send your W5 BUZ, COP, Flu, JC, ZA. W6 AH, AKQ, DEP, BFC, photo to this Corner for publication, the block will BPM, CTI, CQI, RIF, FKK, FTU, GCT, HAW, ITH, JPW, be sent to you later, and you can then have the KCQ, LEIF, LYM, MH, NNR, PB. W7FQK. NV9 FJF, WJJ, l'EL (Colorado). K6 BAZ, BNR, KMB, NIXM, NTV, NZQ, photo printed on your cards. OQE. K7FBE. YE 2BE, HE, 3AFD, DA, EO, ST, 9A1,. Congratulations to Harold Taylor for the neat CO 2EG, JJ, LY, OK, WZ, 3AA, 6031, 7CX, VP, SAE. way he arranges his log, as shown under.It will TI2 AV, FG. HI5X. VP6TR. NY2AE. HH2B, SPA. 11C1FC. XE1Y, GK, 3AR. YV5AA, ABF. OA4AI. LU1H1, help the printers, who have to compose the matter 4BL, SAN. CE1AO, 3CO. ZB1H, IL. FE8AF, AH. HS1BJ. from your copy, if you will oblige likewise. FI8AD. VS TAF, 2AE, AK, AO, 6AB, 7RF. KA 1BH, HS, WI F3HM KY, ME, MH, YL. PK1ZZ, 2WL. VQ4CRE. VK 2HF, UB, AAK VE VV, XU, 3AJ, AL, KX, PE, WA, ZB, 7,1 ZZ, 4BB, 5T1. ADM 2KC 10 metres. W8 3ANF WI AA, ADM, AEP, AJZ, COO, CCZ, DQK, EER, BDS EZW, GJZ, HQN, IFD, IYK, IYE, RIB, WV. W2 AMF, AMM, HGU, INX, ISY, JCY, JIL, JQX, KHI, KHR, KW, BLP SP1HH HI. W3 AIR, AKX, AUP, BJZ, CVC, FGW, FKK, GHS, GSV, JMC, WA. W4 BYY, DRZ, EDD, EF, FT, FL), GB. W5 EHM, FDE, ZA. W7 ECV, FDL. W8 CHQ, EBS, HHH, JFC, KYY, .L. LEVITT, Well Lane, Kippax, Leeds. LIR, PHD, OTK. W9 AGO, BHT, Eli, nEG, SPV, NIDP. 20 -metre 'phone. VU2CQ. VE3ANF. PAM,. W5 FHJ, APM, DUK, BUM, AHK. W6 NMI, ITT!, CUU, COI, KUF, FGU, BAW, OBE, REY, EJK. W7 FQH, DVY. VE3E0, SEW, 3MD, 5PA. VK2XU, PK, XS, APO, S.R.C.C. PARTY 3ZZ, VV, KX, 4BK. CO2JJ, WW, WZ, RA, 60M, 7HF, CX, AT, PA. HIM, 5X, 7G. XE1 FG, GK. V061,, 6V. PY5AQ. An unusual Christmas party for hams is announced LU5CZ. TI2RC. ZBIL, IH. OA4AL. ESSD. VS1AF. ZU6P. by the Surrey Radio Contact Club, to take place on CN8AI, AJ, AM. TF3P. PM. LY1CC, IX. HE9CH, AB. December 14. SP1CC, DC, HH. 10 -metre 'phone. All formality is to be dispensed with, the supper W5 CHG, RV, ZA, AXJ, EEX, FNH, AHJ. ZV. W6 JT4, being in the nature of a ragchew.Special compe- LWN, OZE. W7FCIL W9 VAR, VI,J, YRR, OSO, GUO, titions on bugs and mikes are to be features, together GCT, OSH, GHR, LUV, ZXL, HKZ, and Wl, 2, 3, 4, and 8's.with a lucky draw on the tickets. K6MBT. VE 1DZ, CR, 2KX. V01,J. K4EMG. ZEIJR. ZS 6T, AJ. ZTSJ. ZU6P. VP6Y11. VU2ON. PASJY. Those wishing to attend are requested to advise the hon. secretary,A. B. Willsher(2CCZ),14, N. J. RUTTER, 23, Bouverie Avenue, Swindon, Lytton Gardens, allington, Surrey.Tickets will Wilts. FB8AH. 0Q5AA. VQ4CRE. ZS3F. W5 AIL AKZ, ASG, ECU, be 3s. 6d. each, and the venue, which will be in BEK, BJO, BLW, BVH, COP, CYC, DAN, BEN, FNA, GIB, Croydon, will he advised during the next few days. GPL, VI, ZS. W6 AH, AL, AM, BFC, CNA, CUU, DEP, WC, The next meeting of the club will take place on FDN, FFN, FTU, GCT, ITH, JKR, JPW, JTF, LYM, MWD, December 7 at The Alhambra Hotel, Wellesley Road, NNR, QD, SKK. W7 DNP, ERA, FQK. W9 CXG, WJJ (Denver, Col.). W1OXDA. VE4 T,X, MO, OK. VO 1T, IP, 6T), Croydon, at 8 p.m., when a debate will take place 510. XEIGK, LK, 2FC. CE1AH, PAC, AI, CO, DG. CO2AG, on "Should High Power beAbolished?"

34 THROUGH THE WINDOW

volved.The only thing to do, us no better material DISTANCE AND DIRECTION was to be had, was to make the coils "self-support- Does Greenland count as Europe or America?ing," which meant the use of a fairly heavy con- Which paths do signals from New York and Alaskaductor. take? It was soon found that a heavy conductor caused Look at your atlas and you will see how difficult losses, due to eddy current and self -capacity effects. it is to answer these questions.A glance at anSmaller wire could not he used without support, ordinary map indicates that signals from Alaskaso we had to put up with losses.Apart from this came from due west, whereas the true (Great Circle) loss, a serious defect was that of the difficulty of direction is nearer north-west. making the coil plug-in with more than two connec- To solve these, and many other problems, Webb's tions to it.The addition of a link to feed a low Radio have produced two unique aids, a radio globe impedance lineto the aerial,or another stage, of the world, and an azimuthal map. necessitatingfiveconnections,producedfurther The globe is a 12 -inch globe with a difference. difficulties, and in general it has been necessary to The prefix of every country is clearly marked (thecompromise between optimum coupling and me- prefix being special letters allotted to each country chanical mounting. so that the nationality of stations may be recog- The development of specialceramicsfor high nised-similar to the "GB," "F,' etc. to be seen frequency work now enables a coil to be wound on on cars when touring abroad), the various time zones a former which entails practically no loss and which are indicated, and the boundaries of each continent simplifies the problem of mounting when a number are shown according to the I.A.R.U. definition,of taps are to be used. enabling the user to ascertain immediately the conti- The Raymart Company has been quick to realise nent to which any locality belongs. the electrical and mechanical advantages of this To find the true radio path between any two material, and have now produced a range of plug-in points is simple.A piece of thread is stretchedtransmitting coils, covering from 20 to 160 metres, between them, when the true direction can be seen.and possessingall the features mentioned. The This is a great help in erecting an aerial in the beststandard model consists of a centre tapped coil, position for maximum results from particular direc-wound on special low -loss ceramic former, having tions.A scale is provided so that the distance can three plugs, and designed to mount in a three-point. be readily calculated. socket.The prices have been fixed at 10s. 6d. per Finished in oxydised bronze this world globe is coil, and Is. 6d. for the socket. an attractive addition to any shack or room.The price is 27s. 6d, A NEW TUNING PACK An azimuthal map looks peculiar compared with The "Transatlantic" tuning pack manufactured a Mercator's, the type normally used.With a Mer- by The Mains Radio Development Co. will be found cator's projection it is impossible to plot the Great suitable for the home constructor who wishes to con- Circle distance between two points, but using anvert his old broadcast set for all -waveperation. azimuthalprojectionthecountriesare "moved The pack consists round" so that not onlyistheir true directionof a complete high - shown, but also the distance between places can frequency stage of a be measured accurately. receiver and has a An examination of a normal type map will show pre -selector valve, that degrees of latitude vary, getting larger as the triode - hexode fre- poles are approached.Measurements of distanceq u e n c y changer, . from north to south are therefore inaccurate. andoneinterme- This azimuthal map, centred on London, is cor-d i a t efrequency rected for this defect.Designed expressly for radio valve. There are use, such vital information as international prefixes,t w ointermediate time zones, etc. is shown, and it will be found a transformers so that valuable adjunct to the equipment of any listenerthe output from the or transmitter. i.f.valvecan be Printed in colour on art paper, size 40 inches by takendirectto a 30 inches, the cost to amateurs is 4s. 6d., while adouble -diode triode second detector/a.v.c., there- de -luxeedition,printedonglazedlinen,and fore a.v.c. may be applied to a terminal on the mounted on rollers, will he available at 10s. 6d. chassis. An existing amplifier may be used, or the, makers NEW TRANSMITTING COILS can supply associated stages.Prices for the tuner are, two -gang, 49s. 6d., and three -gang 69s. 6d. For many years the "fashionable" transmitting Ranges are 12 to 80 metres with medium and coil has been the self-supporting type, using heavy long -wave bands.Photograph above will convey gauge copper tube or wire.The reason for this goes the compactnessof the larger model we have back to the old 440 -200 -metre days, when it wasfor test purposes which are not yet complete, and customary to wind a medium gauge wire on some results to date indicate that the attention paid to sort of former, usually of the ribbed ebonite type. constructional detail has reflected favourably on When everyone went "short-wave" it was foundperformance; components are all by factors of high that the material of which these formers were maderepute, thus the prices quoted above represent the was very inefficient at the higher frequencies in-highest standard of value.

35 A Week -end from Ten to Eighty Metres

By A. W. MARRIOTT (5.-W.M. Advertising Staff)

As A COMMERCIAL operator I must confess that I only a few, sending their call -signs incessantly, pre- have looked down with contempt upon short-waveceded by a few v's and often followed by ABC. One listening, and the simple apparatus used.Chal- wonders if they ever send any traffic.PPX sending lenged to give reasons for this attitude, I had to at 27 words per min. on approximately 14.5 m. often admit that I had no experience of s. -w. listening,repeats words twice and is an excellent station to so I readily accepted an invitation to test a simple copy for those wishing to improve their speed. A short-wave receiver, and record my impressions, and little higher up on about 15 m. a commercial sending it is hoped that the following account of some ofpress news in English at 30 words per min. was the happenings heard on these wavelengths will be tuned in.This speed I might mention was actually of interest to other readers.All times are G.M.T. timed and incidently is just about my limit. I simply and wavelengths as near accurate as possible ;the had to spend 10 minutes copying for the sending teat took place during the week -end November 6. was perfect, automatic no doubt.Time 21.30-21.40. My receiver was the S. -W. MAGAZINE One-Valver, Perhaps some enlightened reader can identify this using a pair of Brown's headphones, 120 v. h.t. and station. the same aerial as used for medium and long -wave reception (50 feet total length and 25 feet high). Back to the Lower Band Locality : Southend-on-Sea. The ten -metre band was now tried again but noth- ing was heard so a change up to 20 was made C.W. on" Ten," where a running commentary on a rugger match, 'Phone on " Thirteen "and " Nineteen " in characteristic American style was heard at 21.55. Switching on at 16.30 on November 6, with theThe Big Bad Wolf (a term of endearment, appar- 10 -metre coil plugged in, search was made on thisently, for one of the players) being very much in band till17.00.During this time W8LYQ was evidence.Sigs. R7.The period spent listening to heard calling G2WD, and both VE4JV and W6FZA this station wasn't long enough to identify. At calling CQ dx ten.No contacts appeared to have 22.16, W2TY of Long Island, New York, was heard been made. Then at 17.05 W9RIA was heard work-calling ON4WF in Belgium on 'phone pith little ing G5RRI on ten, telling him that he had called fading.From 22.30-22.55severalstationswere him "plenty," and that QRM was bad and QRK? heard, which, judging by the type of music being All these stations were on c.w. and sigs. R3 to R4. transmitted were South Americans, and quality was The 13in. band was next tried and at 17.10 poor.During this same period a station in Havana, W2XE on 13.9 m. was tuned in, the volume beingCuba (rest of call lost through QRM) was heard on truly surprising for a receiver using only one valve. 'phone telling F8BC that he couldn't get him on Various musical items by Bob Gibson's Band were account of QRM from English, Canadian and South played and announced.There was very little fadingAmerican stations.Sigs. were about R6. and sigs. R5. A change to 19.5 m. was made at It was decided to try something nearer home and 18.00 and an announcement "this is W2XAD, theat 23.00 it needed no searching to find Rome 2R0 General Electric Company of Schenectady, relaying on the 31 -metre band, on 'phone, giving news in a programme from WGY" was heard with practi- English. His sigs. were R9 but there was deep cally no fading. A little above W2XAD a talk in fading.A German station around 49 metres was German by a lady from Zeesen (DJQ) which was tuned in at 23.30 just in time to hear the end of preceded by a bugle call. the programme and the announcer, using English, sending special greetings to the fair sex and an- Learn Morse ! nouncing the programme for next Saturday at 23.00. For those who can read Morse a vast field of By this time BED was calling (sigs. R9 plus) and interest and entertainment opens up.At 18.30 two- having a dislike for burning the midnight oil it was way communication on 20 m. c.w. between U1C0 decided to switch off for the night and resume the and G8FZ was followed, UICO thanking G8FZ forinteresting search next day. report and very nice QSO and nice dx, and telling him that he was using 20 watts, and G8FZ replying Sunday -10 metres again "ur 20 watts f.b. hr. input 25 watts, 73's so long." On Sunday morning, a ten-minute spell from Sigs. from U1C0 were R3, Morse speed about 23 09.30-09.40 was spent on the 10 -metre band and words per min. and both note and sending of U1C0 during this short period G6DH was heard calling were excellent.His Morse was indeed a pleasure "test ten," and UK3AH calling "CQ ten."Both to read.The QRM was rather bad, but that's thewere on c.w. and sigs. R3 and R2 -R6 respectively. great advantageof c.w.-you can get through. Listening in earnest, however, was not commenced Whilst on the subject of Morse it may be as welluntil 11.00 when the same band was again tried to mention the numerous commercial c.w. stations and at 11.05 UK1CC was heard on e.w. calling CQ between the amateur bands which are heard atand telling someone that he was "getting off the colossal strength most times of the day.Such sta- band."His sip. were R3.Going a little higher in tions as JNB, EAV, WSC, and PPX, to mentionwavelength, the commercial station DFJ on about

36 15 metres was heard calling LQC in Argentina on c.w., sigs. R7, speed about 8 words per minute. Final Listen Round Having a weakness for Morse it was decided to No results worthy of note were forthcoming on see what the commercials were doing and from 11.15 the 80 m. band during Saturday and Sunday and it, to 11.30 several messages to ships from IAC Rome% would be interesting to know if other readers had on about 19 metres were copied.Most of these were the same experience.Since 80 was dead and there in Italian but some were in English.Judging by was too much QRM on 20 and 40 to be comfortable the faultless regularity of the sending I should say the ten -metre coil was put into service again.Both that this was mechanical, speed being about 23 W8MCQ and W9VBQ were heard calling "CQ ten," words per min. and sigs. R9 plus.At 11.35 press on c.w., and at 16.42 W8QOK, also on c.w., was news in English at 17 words per min. on about 20 telling EI5G that his sigs. were f.b. and that he metres was copied, sigs. again R9 plus.This station must eat also.(Evidently the inner -man calling). was not identified, but perhaps some reader can There is no doubt that the 10 -metre band is truly supply the data. interesting and daylight appears to be the best period for listening.There is practically no static, The Hams on " 20 " very little QRM and no one seems to send more than 10 to 12 words per min. on c.w. when working Up to now no special endeavour had been made toon this band. see what the amateurs on 20 were doing so a change At 16.55 a broadcast station, sigs. R4, kept me to this wavelength was made at 11.40.The QRM wondering for 5 minutes who it might be and after was simply terrific so that during ten minutes of waiting patiently for the announcement discovered listening no station could be identified.At 11.50 this was GSG on 16.86 metres ending the programme a 'phone station with a woman commentator waswith the musical item "Agitated Ivories" and the heard on this band describing, in English, the cele-announcement "good night and good luck wherever brations of the 20th Anniversary of the Russian you are."I expect all short-wave listeners have Revolution,but was not identified.At12.10, experienced the same disappointmeent, but it does GI5QX, Belfast, was heard on 'phone, at R8, calling at least give a useful check to the tuning of the "Test 20," but owing to the racket the station con- receiver. tacted was missed, however, GI5QX was heard As nothing of particular note had yet been heard telling someone that "last night dx was very goodon 40 metres this band was tuned in at 19.30 and but the night before was the star turn of the monthGI2CC was heard working ON4DMC on 'phone. for dx, QSA5 R8."His remark, "exactly like 40 Sigs.were R9 withlittlefading and excellent. this morning" seemed to imply that he was alsoquality.Apparently ON4DMC had difficulty with experiencing QRM. Then G5SO was next pickedEnglish so GI2CC repeated his report in French, out of the racket calling "hello test 20 metres" onand although I am not conversant with the French 'phone, contacting G8KW whom he told he hadlanguage his dit dit dit dah dit dah bon soir" cer- worked before on 40.His sigs. were R8. tainly sounded "tres bon" to me. During this same period several amateurs were Well, I had had a, week -end of real entertainment using c.w. and the sending of some is not all that and was convinced that there is as much interest. may be desired.Call -signs, which of necessity are below 200 metres as above, so at this stage closed sent three times, are run into one another with the down too.Finally, I would say to all who are pro- result that, if for any reason one should miss thecrastinating over learning Morse-don't--you are first letter or two, a general sorting out has to be missing a new field of interest and entertainment. done before one can find where the call begins and ends.You would think they had never heard of "spacing." Many 'phone stations were still coming through and at 12.40 G6KF, Liverpool, was heard R.S.G.B. ANNOUNCE FIRST 56MC calling and testing and asking for reports of his INTERNATIONAL CONTEST transmission.Another station on 'phone at 12.44 Tostimulateinterestin 56 -me. operation, -? Washington calling G5BN, but the rest of the R.S.G.B. have arranged an international contest on call was swamped by QRM.Conditions on 20 were this band, starting January 1, 1938, ending Decem- certainly very bad. GM8CN was heard on o.w. ber 31, 1938. telling G2HK that he had a contact with a W2 which Scores will be computed from the distance between was not too good on account of heavy QRM, and at stations, the allowance being : 13.10 G2UK was calling G6CT on 20 in. c.w., but 1 point for contacts between 200 and 1,000 miles.

again QRM prevented me hearing if he contacted 5 points 1,001 2,000 .. him.Sigs. from G2UK were R9 plus. 10 points ,, 2,001 3,000 This being one of the unlucky days, apparently. 15 points ,, 3,001 4,000 for 20 metres it was decided to go to the more etc. peaceful region of ten, and here, at 13.36 W9WSY The test is open to any amateur possessinga on c.w. was calling G2XC ten-sigs. R1 to R5 which 56-mc. permit, and entrants must submit a monthly faded right out at times.Morse speed 18 wordsreport of stations worked or heard, together with per mm. G2XC was not heard to reply.By waynotes on conditions experienced, power used, and of change from amateur 'phone and c.w. the broad- any other information of value. cast station W2XE, Wayne, on 13.9 m. was tuned To count points, the same station must only be in at 13.45, just in time to hear the tail -end ofa worked once within a seven-day period, and all "Lyric Serenade" and the commencement of "Radiostations must be operating at their fixed address, Spotlight."Sigs. were R4 and fading slight. not portable. Not having yet heard VK2ME an effort was made An excellent rule is that all entrants mustuse to fetch in this station and an hour was spent from d.c.c.w., 'phone or modulated c.w. being definitely 15.00 to 16.00 searching the 31 m. band, but the banned.This will ensure the use of decent modern only reward was the German and Italian Broadcasttransmitters, the development of which has beenso stations operating. retarded by the use of "wobbulated" portablegear.

37 "ON THE AMATEUR BANDS"-cont. from p. 13. We haven't had much time to experiment in this so I am looking forward to seeing his new station.direction, but what little we have done shows Austin Forsyth, G6FO, our designer, spent an promise.At any rate it is interesting work, and is evening with me during a short visit to town.Foura line of experiment for those with A.A. licences to hours talking "shop," but we enjoyed it.I live while away the time waiting for a full ticket. 100 yards from the main Brighton road, so he was able to hear some real man-made static. Anode Bypass Condenser He is putting the finishing touches to an exciter Many amateurs using 1,500 volts h.t. use a 1,500 - unit using a couple of Tungsram APP4G's.Sounds volt working bypass condenser.With a class C final a hot job to me, practically all -band operation with the anode volts applied may be only 1,500 but the a 1.7 mc. crystal, enough kick to drive a 50 -watt peak volts are nearer 4,000.No wonder -condensers final, so look out for it soon. blow.When anode modulation is used the peak Another thing he is doing is arranging some testsvoltage is at least doubled, and the condensers afe with U.S.A. on 1.7for early next year.Anyone more apt to give way.That so few breakdowns do interested? occur is due to the factor of safety the makers allow, but this condenser is worthy of more attention than Ancient History is usually paid to it.I have been stations where 0. M. Davies (2PC) is another old timer comingevery care and expense has been made to get the back to the game.He mentions 2AZ, the late utmost efficiency, yet a most unsuitable type of con- William le Quex, who was an ardent "ham" arounddenser has been used in this important position. 1922.Of the others 2KW is now in the talkieR.F. watts are precious, don't waste them in the game, 2KF in the B.B.C., and 2NM (of Empiretransmitter, they are more valuable in the aerial. Broadcast fame) still comes on occasionally. Have a look at your anode bypass, it may he the 2PC helped at 2KW during the early trans - cause of erratic operation on 28 mc. Atlantic tests.Paul Godley came over from U.S.A. on behalf of A.R.R.L. to listen for yank signals. He brought over a colossal superhet, which he used in a tent at Ardrossan, Scotland, in conjunction with a Beverage aerial.2PC says his memories of CLUB ACTIVITIES the tests chiefly consist of rising at 2 a.m. and Reports for inclusion under this head must reach us cycling to Sale, where he listened with his friend by the 15th. on a 3 r.f.-v-2 1.f. receiver he and 2KW made for the job.Tuning it was like trying to work out the BIDEFORD combination of a safe :ganging was unthought of On November 3 the Bideford and District Short - then, but they did have some luck in the tests. Wave Society successfully held its second annual Later 2KW got a 1 -kw. permit, and rigged up adinner, and were honoured with the presence of transmitter with home-made transformer and ump- G6GM (Holsworthy), and Mr. A. Cornish (Torring- teen jam -jarsfor an electrolytic rectifier.Every ton Radio Society) and its members; other amateurs time the key was pressed all the street lights blinked present were G6FO, G8US and 2ADJ. in sympathy ! On November 8 tests were carried out with a "Stentorian" speaker.This was voted fine busi- Contacts wanted ness, and the Society decided to procure one for its H. Hirschberg, of Clapham, S.W., writes that on own use.Anyone interested in membership should a card from W5FAG, it states that this is his firstapply to the Hon. Secretary, Mr. W. G. COUCH, European report, and that he would like contacts "Hillside," Glen Gardens, Bideford. with this country.He is on every weekend, 14 mc., BOURNEMOUTH-POOLE 'phone and c.w. It is proposed to form a club in the Bournemouth - QRU, 73, Merry Xmas, QSK, SK. Poole area to meet monthly, under the title "The East Dorset and West Hants Radio Club."The co-operation of G5CH has been obtained and others "QUERIES"-continued from p. 14. in the district are being approached.The proposed average power will drop, and we shall be able to subscription is 5s. per annum.Enquiries would be useHeisixigmodulation withouttheenormous welcomed from anyone in the area interested, and battery drain when constant carrier 'phone is used. these should be addressed to DAVID M. WILLIAMS Using a class B modulator the modulator valve (BSWL 832),Provisional Secretary, "Amberley," will not take power when there is no speech being Cromwell Road, Poole. transmitted, so we do not have to worry about this valve.The problem that remains is to prevent the BRIGHTON p.a. from taking power, which can be done either A Brighton Chapter of the British Short -Wave by giving it a high negative grid bias, or by eitherLeague was inaugurated on November 26 with a cutting off the power to the c.o. or making its grid good attendance.The meeting consisted of electing so negative that it stops oscillating. the necessary officials.Members' achievements and Various ideas are : the use of relays to cut off theQSL cards received were discussed and inspected. h.t., or a rectified voltage for the bias obtained fromRegular meetings have been arranged for the winter. a rectifier (a Westector for preference) operating inAnyone interested should write to the B.S.W.L. the output circuit of the driver stage for the classT.R. for Brighton :N. OWIDN (2AFO), 6,Elder B valve. Street, Brighton,l.All are welcome. A delay circuit will also be necessary, otherwise DOLLIS HILL speech will be cut off between syllables, but this is Ten -metre transmission and reception will form only a minor matter, which can be added when thethe subject of a talk by Mr. H. Wilkins (G6WN) to control circuit has been designed. members of the Dollis Hill Radio Communication

38 Society, on December 7.A "Simple Mathematics one radio signal produced three and five separate and Ohms Law" talk is arranged for the December echoes.The lecturer went on to say that the lower 21 meeting.The honorary secretary, J. R. Hong- layers were discovered two years ago and they only KYNS(2CQF), 102, Crest Road, Cricklewood, N.W.2, existed in the summer and it is these layers which extends an invitation to interested persons to attend'are designated D1 and D2 which affect ultra short- these meetings at the Brancroft Schools, Warren wave radio work.Solar activity and its effect on Road, at 8 p.m. cable and radio transmission was also dealt with. Meetings are held each Monday at 3, Dix's Field, ENFIELD Exeter, at 8 p.m. and those interested should get Although formed but recently the Enfield Radio in touch with the Secretary, Mr. W.CHINO,9, &veil Society has been established on a firm basis and is Place, Heavitree, Exeter. already very active.Meetings are held every Mon- day.Applications for membership have been large, ILFORD and the present members includeseveral"old Last month saw the production of No. 1 of the hands," beginners, together with a number of localIlford andDistrict Radio Society'sBulletin,a hams.It is hoped to arrange an extensive pro- monthly news -letter that has interest .for members gramme for the remainder of the winter session. and non-members alike, for there are technical notes Applications for membership will be welcomed, and interspersed with thoseof more localinterest. should be sent to the Secretary: L. A.FENN,47, Annual subscription is Is. Cecil Avenue, Enfield. The hon. press secretary (H. 1'. STorr, 2COT) in his covering letter says :"You will see by the EXETER syllabus on page 4 that we are as active as ever, At the meeting of the Exeter and District Wireless and despite the alleged 'lowering of interest in home Society held on October 25 Mr. R. C. Lamps, radio construction and activities of an experimental A.M.I.E.E., took as his subject for a lecture, "Direc- nature' (sic) we are able to record at this date that tion Finding."The latest types of apparatus were a number of new membershave joined.On described in detail and the lecture was made more November 12 a representative number of our mem- interesting by the fact that during the last fewbers visited the Southend Society at their H.Q. at months, Mr. Lawes has installed direction finders on Leigh Technical College, where a lecture on 'Modern ocean-going racing yachts, and he himself took part High -definition Television' was given by Mr. Watson in this year's Fastnet Yacht race.The types of of E.M.I.The lecturer gave a most interesting talk, errors which are likely to be found in the practicaland went very fully into many points of his sub- application of this side of radio engineering were ject.The proceedings terminated with many ques- described and well illustrated by the lecturer with tions." diagrams. Fixtures for Thursdays in December include, in Mr. Lewes went on to say that he found it quite the following order : Loudspeaker demonstration and practical to navigate any sea -going craft by using talk, Mr. H. A. Hartley; Gramophone demonstration radio alone and he instanced a crossing from Fastnet and talk, 2COT ; Junk Sale ; Informal Evening ; the Rock to the Scilly Islands, a distance of approxi- last evening is open for fixture.Further details will mately 200 miles.On this particular leg of thebe given prospective members by hon. secretary Yacht race no stellar observations were obtained C. E. LARGER, 44. Trelawney Road, Barkingside, owing to thick weather, but the lighthouse on Round Ilford (Royal 4361, Chigwell 126). Island in the Scilly Islands was found with ease.It was also shown by Mr. Laves that it made very little NORTHERN IRELAND difference whether the apparatus was fixed above or The general monthly meeting of the Radio Society below the water line of a ship and lie had no doubt of Northern Ireland was held on November 3, in the that similar success could be obtained from land Y.M.C.A.(Belfast)Club Rooms, with the per- craft such as tanks, armoured motor cars, etc. mission of theAssociation's Radio Club. After Mr. Rumba, during his recent lecture to mem-routine business it was announced that the services bers, demonstrated various makes of car radios inof a professional operator had been secured for the particular and also showed how the many sourcesbenefit of all members who should avail themselves of- interferences could be overlooked.Many newof this splendid opportunity of learning the code in vibrators were demonstrated and also various aerial the proper manner. systems in use for radio installations on cars, etc. On November 6 a visit was paid to the Short- At the November 8 meeting a lecture was given Wave Telephone Link at Ballygomartin byper- by Mr. D. R. Barber, B.Sc., F.R.A.S.The title mission of M. C. Cooper, A.R.C.Sc.I., A.M.I.E.E., of the lecture was "The Ionosphere."Mr. Barber who welcomed the party.Mr. G. Edwards, engi- exhibited numerous slides and took his audience neer -in -charge of theStation, and his two able through the various layers, pointing out the pecu- assistants then took the members on their tour of liarities of each. A remarkable fact proved that in inspection and all are unanimous in their apprecia- the ozonospherethe temperatureisalways30 tion of the perfectly lucid manner in wluch the degrees centigrade, i.e., hotter than the earth's sur- various apparatus was described. face.The two layer!: which are 60 miles and 150 Members are steadily increasing and full particu- miles above the earth's surface are more or less pro- lars may be had from the Hon. Sec., Mr. C. TAYLOR duced by the action of ultra violet rays.The next (2AOB). 2. York Crescent, Shore Road, Belfast. part of his lecture dealt with polarization and here again it was shown that in the northern hemisphere SOUTHEND the left-hand wave was about five times as strong At a meeting held on October 29 Mr. H. G. as the right-hand one, whereas in the southernMenage, of R. A. Rotherinel, Ltd., gavea lecture hemisphere the reverse was the case. to members of the Southend and District Radio and Methods were shown in the calculation of the Scientific Society on "Some Interesting Applications heights of various layers and how radio echoesare ofPiezo-EleotricCrystals."In additionto the recorded.On some slides it was clearly shown howbetter-known applications such as pick-ups, micro-

39 phones and speakers,the lecturer described and TOTTENHAM demonstrated crystal -operated devicesfoltesting Three successful Visitors' Evenings were held on the human heart, checking the movement of watchesthe 11th, 12th and 13th of November by the Totten- and recording vibration in Ipotor car engines. ham Short -Wave Club-the' number applying for In view of the great demand, a further direction - membership was gratifying.Thanks are due to Mr. finding contest was held on Sunday, November 7. Cholot for demonstrating the Lissen Hi -Q short-wave The start was from Rayleigh, Essex and the first componentsandAll -Wave Receiver No.8114. competitor to find the concealed transmitter wasAlthough the aerial system was not of the best the Mr. G. T. Peck, the second being Mr. K. W. Har-demonstration was voted by allas a complete bridge (G2KH).It had been announced that this success. We should also like to thank THE -SHORT= would definitely be the last outdoor meeting in the WAVE MAGAZINE for their kind co-operation, Messrs. present year but it is understood that a petitionStratton and Co. and The Whiteley Manufacturing has been organised, requesting the committee toCo. (for the loan of a "Stentorian" speaker).Con- arrange a further contest as soon as possible.-Hon. siderableinterest was showninthe apparatus Sec., F. S. ADAMS, Chippenham, Eastern Avenue. assembled by club members, and special mention Southend-on-Sea. is due to Mr. Symons for hard work in this respect.. SURREY THE SHORT-WAVE MAGAZINE'S One -Valve Class B The lecturer at the October 19 meeting of thereceiver was assembled and excited interest.-Hon. Surrey Radio Contact Club was Mr. Miles (G2NK), Secretary, EDWIN JONES, 60, Walmer Terrace, Firs Technical Manager of A.C.S., who brought with him Lane, Palmers Green, N.I3. three communication receivers of American manu- WELLINGBOROUGH facturewhichhedemonstrated.Theywere : The fortnightly meeting of the Wellingborough National 101X. with crystal filter, Hallicrafter Skyand District Radio and Television took place at. Challenger, and an R.C.A.111-also a crystal -gateWellingborough on November 10, when a lecture receiver.Mr. Miles explained that as the British and demonstration of THE SHORT-WAVE MAGAZINE manufacturersdidnot market arealamateur Class B battery receiver was given by the hon. sec., receiver, American products had to be imported to Mr.L.F. PARKER (G5LP), who prefacedhis satisfy the needs of present-day amateur radio. Thedescription of the receiver by saying that it was large number of amateurs in the U.S.A. and therefreshing in these days of multi -valve receivers to interference created by crowding them into thesee published a designof a short-wave receiver narrow width allotted had ruled the design of thesecapable of being constructed by the novice at low sets. cost and producing such excellent results as had The sensitivity of all three sets on a six-foot aerialbeen obtained with this receiver. was marked.The selectivity of the crystal -gate The volume obtainable was reallyremarkable circuit was of a degree hitherto unknown to manyand with 150 volts h.t. and a current consumption of the members present.On the National, the dialof less than four milliamperes, the receiver was and the band -spreading arrangements had been so capable of giving quite good loudspeaker reproduc- well arranged that onedivision(a quarter -inch tion of the more powerful short-wave broadcasting space on the circumference of the dial) represented, stations.Sensitivity was of a high order and dur- on the 14 Enc. band 1 kc.Such a spread, the lec-ing a short test all continents were heard on tele- turer assured us, enabled measurements of drift inphony in a little over half -an -hour.The reaction frequency when the transmitter was warming up,control was faultlessand the Eddystone band - to be readily determined. spreading system incorporated enabled even the Of particular interest to those members who are beginner to obtain equal results. troubled with ignition interference, was the highly Even on the very high frequencies above 28 mega- efficientnoise -suppressioncircuitofthe R.C.A.cycles the receiver still functioned excellently and receiver.A hearty vote of thanks to the lecture,: ten -metre 'phone from U.S.A. could be logged when- closed the meeting.The lecturer afterwards in-ever the ten -metre band was alive, showing that formed us that, from our comments and opinions,the receiver was very suitable indeed for amateur much had been learned of the amateur's idea of ancommunication purposes.After the talk, a number ideal receiver which may yet be marketed in thisof questions were asked regarding the circuit and country as an all -British receiver for amateur bandoperation of the receiver and the thanks of the work. Full details of the club may be obtained Society were expressed to the Editor of THE SHORT- from the hon. secretary, A. B. WILSHIRE, 14, Lytton WAVE MAGAZINE for making the interesting meeting Gardens, Wallington. possible. THORNTON HEATH WEST SUSSEX By the time this report appears the Short -Wave The West Sussex Short -Wave and Television Club Radio and Television Society of Thornton Heathwas formed at Chichester on SepteMber 14 and now hope to have erected a new H.Q. aerial which is tohas a membership of 27-more are required.Full be a Windom; they will be pleased to receive recep- details will be gladly sent to anyone interested. tion reports from readers on 40 -meter fone and c.w. A general meeting was held at "The Waggon and transmissions.(Call G8GY). Lamb" on October 5.Our President gave a very A successful and enjoyable junk sale was held interesting talk on his radio reminiscences from 1913 recently and for the first time- radio journals and until the present day.He spoke about his first magazines were sold in addition to the usual run of 100 -watt hcence whereby he was allowed to use components and accessories. this input for two hours a week, his Empire broad- An increase in membership is reported and the castingexperiments,and concluded with some Secretary reminds readers, whether beginners or old advice on transmitter and aerial design.The talk hands, that they are at all times welcome to thewas greatly appreciated by all present.The Club meetings either as potential members or visitors.- is applying for an A.A. licence on all bands.-Hon. Hon. Sec., Mr. JAS. T. WEBBER, 368, Brigstock Secretary, L.A.C. J. WILLIAMS (2BBB), H.Q. Flight, Road, Thornton Heath. 43 (F) Squadron, R.A.F., Tangmere, Sussex. QUERY COUPON S.-W.M. 12/37. 4U Station Dial Call Wavefreq Station Dial rat WaveFrej. PITTSBURGH WSXK 13.9321.54 DAVENTRY GSC 31.32 9.58 DAVENTRY GSJ 13.9321.53 LYNDHURST VK3LR 31.32 9.58 WAYNE W2XE 13.9421.52 NI 'WS WI XK 31.35 9.57 DAVENTRY GSH 13.9721.47 BOMBAY VUB 31.38 9.56 BANGKOK HS8PJ 15.7719.02 ZEESEN DJA 31.38 9.56 DAVENTRY GSG 16.8617.79 PODEBRADY OLR3A 31.41 9.55 BOUNDBROOK W3XAL 16.87 17.78 SUVA (Fiji) VPD2 31.46 9.54 HUIZEN PHI 16.8817.77 ZEES EN DJN 31.45 9.54 ZEESEN DJE 16.8917.76 JELOY LKJI 31.48 9.53 WAYNE W2XE 16.8917.76 TOKIO JZI 31.48 9.53 BUDAPEST HAM 19.5215.37 SCHENECTADY W2XAF 31.48 9.53 SCHENECTADY W2XAD 19.5715.33 HONG KONG ZBW3 31.49 9.52 DAVENTRY GSP 19.6015.31 MELBOURNE VK3ME 31.55 9.51 BUENOS AIRES LBU 19.6215.29 DAVENTRY G8B 31.55 9.51 ZEESEN DJQ 19.6315.28 CARTAGENA HJIABE31.58 9.50 WAYNE W2XE 19.65 15.27 RIO DE JANEIRO PRFS 31.58 9.50 DAVENTRY GST 19.6615.26 MEXICO CITY XEW W 31.58 9.50 BOSTON WIXAL 19.6715.26 MADRID EAR 31.62 9.49 RADIO COLONIAL TPA! 19.6815.24 HAVANA COCH 31.82 9.43 EINDHOVEN PCJ 19.71 15.22 BANGKOK HS8PJ31.85 9.36 PODEBRADY OLR5A 19.7115.23 LIMA OAX4I 32.12 9.34 PITTSBURGH W8XK 19.72 15.21 BUDAPEST HAT4 32.88 9.12 ZEESEN D.TB 19.74 15.20 RADIO NATIONS HBP 38.48 7.80 HONG KONG ZBIV4 19.7515.19 TOKIO JVP 39.95 7.51 DAVENTRY GSO 19.7615.18 SAN DOMINGO HIT 45.25 6.63 Toxic, TZK 19.8015.16 NANKING SOURABAYA lax 19.80 15.15 XGOX43.99 6.82 DAVENTRY GSF 19.82 15.14 VALENCIA YV4RB 46.01 6.52 VATICAN CITY HVJ 19.84 15.12 MARACAIBO YV1RH 47.12 6.36 ZEESEN D.TT. 19.85 15.11 MARACAIBO YV5RP 47.84 6.27 SOFIA LZA 20.2414.88 HAVANA COKG 48.39 6.20 WARSAW SPIV 22.00 13.83 MARACAIBO YV5RD 48.78 6.16 SANTIAGO (Chile) CB615 24.3912.30 WINNIPEG CJRO 48.78 6.15 REYKJAVIK TF.T 24 5212.23 PITTSBURGH W8XK 48.86 6.14 MOSCOW RV59 25.0012.00 JELOY LKJI 48.94 6.13 RADIO COLONIAL TPAS 25.23 11.88 HAVANA (CUBA) COCD 48.94 6.13 PITTSBURGH W8XK25.27 11.87 GEORGETOWN VP3BG 48.94 6.13 LISBON CSW 25.34 11.84 BOGOTA .H.T3ABX48.96 6.13 PODEBRADY OLR4A 25.3411.84 MEXICO CITY XEUZ 49.02 6.12 WAYNE W2XE 25.3611.83 WAYNE W2XE 49.02 6.12 LISBON CTIAA25.3611.83 CHICAGO W9XF49.18 6.10 ROME I2R04 25.4011.81 BOUNDBROOK WIXAL 49.18 8.10 TOKIO JZ.T 25.4211.80 BELGRADE YUA 49.18 6.10 VIENNA OER2 25.4211.80 TORONTO CRCX 49.26 6.09 BOSTON W1XAL 25.4511.79 HONG KONG ZBW2 49.26 6.09 ZEESEN D.TD 25.49 11.77 NAIROBI VQ71.0 49.32 6.08 DAVENTRY ORD 25.5311.75 CHICAGO W9XAA 49.34 6.08 HUIZEN PHI 25.57 11.74 LIMA OAX4Z 49.33 6.08 WINNIPEG CJRX 25.6011.72 GEORGETOWN VP3MR 49.42 6.07 RADIO COLONIAL TPA4 25.6011.72 MARACAIBO YVIRD 49.42 6.07 HAVANA COCX 26.2411.43 PHILADELPHIA W3XAU 49.50 6.06 RADIO NATIONS HBO 26.3111.40 CINCINNATI W8XAL 49.50 6.06 BUENOS AIRES LSX 28.9910.35 COPENHAGEN OXY 49.50 6.06 MOTALA RUYSSELEDE ORK 29.0410.33 SBG 49.50 6.06 LISBON BOGOTA HJ3ABD49.59 6.05 CSW 27.17 11.04 BOSTON MADRID EAQ 30.43 9.86 W1XAL 49.67 6.04 PANAMA CITY 49.75 6.03 HAVANA COCQ 30.77 HP5B 9.75 ZEESEN DJC 49.83 6.02 LISBON CT1CT31.00 9.68 BOGOTA BUENOS AIRES HJ3ABH49.85 6.01 LRX 31.06 9.66 HAVANA .COCO 49.85 LISBON CT1AA 31.09 9.65 6.01 PODEBRADY OLR2A 49.92 6.111 CARTAGENA HJ1ABP 31.25 9.62 MONTREAL CARACAS 9.60 CFCX 49.96 6.00 YV5RA 31.25 MEXICO CITY XEBT 56.00 6.00 MOSCOW RV96 31.25 9.60 MOSCOW RADIO NATIONS RW59 50.00 6.00 HBL 31.27 9.59 VATICAN CITY HVJ 50.26 5.97 PHILADELPHIA W3XAU 31.28 9.69 MARACAIBO YV1RB 51.28 5.85 SYDNEY VK2ME 31.28 9.59 CARACAS YV5RC 51.72 5.80 EINDHOVEN PCJ 31.28 9.59 KHARBAROVSK RV15 70.20 4.21 G2NO G2CY H. R. ADAMS WEBB'S H. W. STEWART SELECTED ITEMS FROM COMMUNICATION OUR LIST PRODUCE THE TYPE RECEIVERS MICROPHONES RADIO AMATEUR'S GLOBE Shure. 701A.Grill type. 84/- RME-69. 1938. Astatic D104 75/- The Amateur's finest receiver Webb's TransverseCarbon, Price /39 ISs. Od. with table stand. 25/ - AND MAP OF THE WORLD With floor stand. RME-69-LSI. Incorporating the famous Lamb VALPEY CRYSTALS Noise Silencer unit. 7 Mc. mounted. Price /43 10s. Od. Calibratedto-- or - .1per cent. IS 6 RME-DB.20. Unmounted, as above 10 6 12" Radio PRICE Two -StageH.F.Pre -Selector. DUMONT CATHODE 9 to 550 metres. Globe Built-in Power Pack (230v.). RAY OSCILLOSCOPE. Price 112 10s. Od. Model 164.3 -in. tube. 27/6 Vertical and Horizontal Ampli- Mounted, 1938 HALLICRAFTER. fiers.Amplified sweep. The New SuperSkyRider Internal Power Pack. Fully Crystal Gate, " R " Meter. Price complete 18 guineas 1,000 deg. Band Spread. 913 1 -in. Cathode Ray Tube. Coloured 5 to 550 metres. 37 6 Price 230-v. model 132 Os. Od. ACORNS.Price reduced. International Immediate 1938 SKY CHALLENGER Type 955 Triode. 25 6 9 Tubes. Types 954, 956 Pentodes. 36' - Delivery Fully calibrated. Prefixes 9 to 550 meters. RAYTHEON TUBES Crystal Gate. RK-34 Duplex Transmitting Price 230-v. model E25 Os. Od. Triode. RK-39 Beam Power TX. 22/6 1938 SKY CHIEF RK-47 (Beam Power RK-20). 7 Tubes (I R.F.). 105,- Built-in Speaker. 100-TH, New Eimac. 95,-RK-20A EQUIDISTANT AZIMUTHAL MAP OF THE WORLD Price complete 112 10s. Od. replacing RK-20. 95/- CENTRED ON ENGLAND RK-25 and RK-23. 27/6 ALL INTERNATIONAL PREFIXES MARKED THE NEW SKY BUDDY. TAYLOR FULLY COLOURED. SIZE 30 in. by 40 in. 5Tubes. 17 to 550 metres. Taylor T.125. E4 Ss. Od. 17,6 PRICE Built-in Speaker. Taylor T.20. 4 6 Price complete 69 Os. Od. Taylor TZ.20. 17/6 A limited number of Maps mounted on linen, with roller, at 10,6. Taylor 866 Junior. 7/6 NATI ONAL. Taylor 866 11/6 BOTH AVAILABLE DECEMBER 1st. Taylor T.55 45/ - National " One -Ten " ThefinestU.H.F.Receiver. POWER TRANSFORMERS TED McELROY, WORLD'S CHAMPION TELEGRAPHIST, RELEASES NOTE REDUCED PRICE. Filament Transformers, single A NEW STRAIGHT KEY. Complete with Tubes. winding. Up to 30 watts. 12/6 118 10s. Od. Twin Winding, up to 30 watts. LARGE CONTACTS. HEAVY CAST BASE. DELIGHTFUL ACTION Price 10 - Power Pack /4 10s. Od. 15/6 MAC OSCILLATOR. National H.R.O. Senior Triple Winding, up to 40 watts. Price complete 149 I5s. Od. FOR PRACTICE. PRODUCES A 1,000 CYCLE NOTE - - 10; - 19f - National H.R.O. Junior. High Voltage Transformers. KEY AND OSCILLATOR COMBINED 20 - 750-0-750 at 200 mils,inter- Price complete /39 I5s. Od. leaved. E2 I3s. Od. '938 McELROY BUG KEY 38'- 1,000-0-1,000 at 200 mils. NEW NATIONAL 80X 13 I5s. Od. Delivery isexpected Decem- 1,000-0-1,000 at 350 mils. ber 1st. /4 10s. Od. WEBB'S CARRY THE STOCKS A.C. 'D.C. Operation. 1,000-0-1.000 at 500 mils. Price 123 Os. Od. ES Os. Od. WEEKLY CONSIGNMENTS Swinging Chokes. HARVEY TRANSMITTERS 5 to 25H at 100 m.a. 15/6 DIRECT FROM THE FACTORIES OF UHX-10 5 to 25H at 200 m.a. 21 /- 10 to 20 watts R.F. Filter Chokes. RME, HALLICRAFTERS, TAYLOR, RAYTHEON, HARVEY, etc. 5 to 160 metres. 20 Henry at 120 m.a. 15/6 Crystal Control. 20 Henry at 200 m.a. 28/ - ASSURE THAT YOU RECEIVE PROMPT DELIVERY AND BRAND NEW GOODS Price Transmitter bare Other sizes to order. EVERY MEMBER OF OUR STAFF IS A 100%' OLD TIMER,' THOROUGHLY /16 15s. Od. HAPPY INHIS WORK OF MAKING WEBB'S THE AMATEUR CENTRE CLEARANCE OFFERS. HARVEY 80T Mu -MetalMicrophone Trans- Complete for two -band opera- formers (cost 55 each).7/6 CALL AND ENJOY A PERSONAL CONTACT tion. [63 I7s. Od. Mu -Metal Smoothing Chokes. 5.2H, 120 m.a. 3/6 UHX-35 4 -In. Transmitter Bakelite Dials. 20, 10, 5 and 2i.! metres. i-in. spindle. 6d. each 100 watts input. WEBB'S RADIO Price complete £110 Os. Od. EDDYSTONE ALL -WORLD TWO, complete with valves, (C. WEBB, LTD.) coils, calibration chart, ready WRITE FOR LIST AND for use. Price E3 In. 6d. 14 SOHO STREET., OXFORD STREET, LONDON, W.I. DETAILEDHIRE- Aerovox 2 mfd. 2,000 v. WKG. Phone :GERrard 2089 PURCHASE FACILITIES Midland Depot :For Callers Only : G6VA 41, CARRS LANE, BIRMINGHAM. WIJYN E. J. PICKARD Phone : Midland 3771 TED McELROY

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