In this Issue :

RECEIVER TYPES ANDPROPERTIES.

DENCO COIL DATA.

BROADCAST NEWSOF THE MONTH.

ON THE HAM BANDS.

MY FAVOURITERECEIVER.

HAM QUIZ, etc., etc.

CONSTRUCrIONAL.

THE SHORT WAVE NEWSFREQUENCY METER.

THE BSWL MULTI -RANGEMETER.

Vol. I.

No. 2.FEBRUARY, 1946

ALL -DRY FREQUENCY METER(Constructional details within.)

SHORT WAVE PRESS 1 13PUBLICATION.

SHORT WAVE NEWS

EbERYlHING for the Amateur!SO many of our customers tell us that we have the finest display of new Radio

Components in England that we are beginning to believe it ourselves.

Frankly, we are pleased-because, despite the shortage of supplies and other diffi-culties, we have worked hard to make our shop a centre of attraction for theAmateur.

If you are building a transmitter, communications receiver, high fidelity audioequipment or test apparatus, come along and see us-we can help you-andsupply all the components you want. Even if you are only starting on your firstcrystal set, you will be just as welcome and will receive the same courtesy andskilled attention that has made some of the best known Amateurs in the countryour frequent and regular customers.

If you cannot yet call, send along a 21d. stamp for our price list.

TELE.RADIO (1943) LTD.177, EDGWARE ROAD, LONDON, W.2.

Telephone : PADDINGTON 6116 LTD

CU Agn OB .

in this journal-with the latest developments inmeasuring instruments designed for Hams.

Meanwhile, here are two Series 35 Rectangular Instru-ments which will interest you.

Foundation instruments to

build your own Multi -Range

Test Set as described in this

issue. 1 mA F.S.D. 100 ohm

res ; scaled 0-I with 50

divisions or 3 column Multi -

Range dial with ohm scale.Price, 89/-.

MEASURING INSTRUMENTS(PULLIN) LTD

WINCHESTER STREET, LONDON, W.3.4 f correspondence to be addressed to : Phoenix Works, Gt. West Road,

Brentford, Middlesex. Tel. : Ealing 0011.

11

Pullin Instruments will en-hance the appearance ofyour new TX, whateverthe assembly. Obtainableonly from our Authorised

Distributors :

WEBBS RADIO, 14, Soho St.,Oxford St., London, W.I.TELE -RADIO (1943) LTD.

177 Edgware Rd., London, W2RADIO -MART G5N 1 (B'ham )

LIMITED. 48, Holloway Rd.,Birmingham I.

C. WEBB LTD.Carrs Lane, Birmingham.

HOLIDAY & HEMMERDINGERLIMITED, 74-78 Hardman St.,

Manchester, 3.WELWORTH WIRELESS

& ELECT. COMPANY,8 Withy Grove, Manchester, 4

SHORE WAVE NEWSVol. I. No. 2. Annual Subscription, 16-. February, 1946

Editor : ARTHUR C. GEE, G2UK. Asst. Editor : W. NORMAN STEVENS

Advertisement & Business Manager : C. W. C. OVERLAND, 2ATV.

First Impressions and Future Plans. EDITORIAL

This editorial is being written justafter reading the first batch of lettersfrom readers of our number one issue.It is very apparent that we havemanaged to fill a gap, in the literatureavailable for the short-wave enthusiast,which has remained vacant for far toolong. We wish to thank all those whohave written wishing us success. Itshould be pointed out though, that whilstwe realise that we have made a creditablebeginning considering the difficulties ofstarting a new periodical in these try-ing days, the magazine in its presentform is far from the type of publicationwe hope eventually to produce. Ourmain difficulty at present is the verymeagre allocation of paper granted tonew periodicals, and we owe a debtto our printers for doing so well withwhat we get. As the paper situationeases, so will the magazine increase insize. Already, we learn of the possibi-lity of a little larger paper quota inthe very near future which should en-able us to add another four pages toeach number, and to increase our cir-culation somewhat. We are now, too,receiving material for articles which wefeel sure will make the Short WaveNews really good value for money.In this connection, we hope ourreaders will write to us and let us havetheir views. Readers' correspondenceis the only really reliable guide anEditor has to the views and require-ments of those readers, so please donot hesitate to write us.

THE NEW TRANSMITTINGREGULATIONS. The most interest-ing feature about the new licensingregulations is that the " experimentalstation" designation has been dropped,and in its place there has been sub-stituted " amateur radio station." Aswe pointed out in our first editorial,this step has been long overdue and itis good to find the authorities takingthe opportunity of a new " beginning "to initiate this alteration in status. Thefrequencybe 28,000 kcs.-29,000 kcs. and58,500 kcs.-60,000 kcs. Those whoheld a pre-war radiating licence willbe permitted to use up to 100 wattson the first of these bands and 25 wattson the second, phone or C.W. Those

' with an A.A. licence will be limited to25 watts on both bands,' C.W. only atfirst. Operation on the other inter-nationally allocated amateur bands willbe allowed when such bands can bereleased by the military authorities.The issue of licences to new applicantsis still under review at the time ofwilting these notes. Such applicantswill be required to satisfy the Post-master -General as to their technicalqualifications and morse proficiency,either by passing the City and Guildsof London Institute "Radio Amateurs"examination or by reason of exempt-ing technical qualifications.-a list ofwhich will shortly be published. Wehope to give details of the " RadioAmateurs " examination in the verynear future. A.C.G.

27

SHORT WAVE NEWS

My Favourite Short Wave Receiver.(BSWL 579)

This is the second of the series of articlesdescribing favourite receivers used by ourreaders, to whom the block of the thep-retical circuit is presented. Contributionsare invited on this subject, consisting ofsome 500 words and circuit drawing.

This month we present the Duo -Oneowned and constructed by Harold Lister ofPocklington, York. As he says, there isreally nothing remarkable about this setfrom the technical point of view, but thereis the satisfaction of getting something fornothing, in the sense, that this single -valvereceiver does give two -valve performance.

The receiver was built from surplus com-ponents, on a chassis measuring 8 inchesby 7 inches, with 21 inches under thechassis. These dimensions are ample, andallow for future alterations and/or addi-'tions. The values shown for the variouscomponents do not seem to be very critical.Reaction is quite smooth. In the writer'scase, it was found necessary to use anadditional series capacitor-a piece of flextwisted round the lead-in-when connectedto an 85 feet inverted L aerial, in order

to remove one or two " dead " spots. Thiswould not be needed with the averageaerial. It was also found that best resultswere obtained when LT+ was taken to earth,instead of LT- as is more usual. Somelittle time was spent experimenting withdifferent combinations for the grid leak andcapacitor, in order to get as smooth reac-tion as possible..

The RF choke was wound on an eboniteformer a inch diameter, with 150 turnsof 36 swg. DSC wire, these being pile woundin five sections. All components with theexception of the tuning capacitors, coil,and valve were mounted underneath thechassis. A 120 volt H.T. battery is used,it being found that reaction is difficult toobtain with less than 100 volts; 11 voltsgrid bias is applied to the audio section.

The receiver has given a very goodaccount of itself, and many DX signalsfrom all parts of the world have beenlogged. H. Lister ends by suggesting thatthis circuit would form a good foundationfor a more selective receiver having a tunedRF stage, and also has possibilities as aportable for Field Day use.

SHORT WAVE NEWS

On the Ham Bands.Conducted by " CQ "

As this article is being penned, good newsis filtering through from all quarters con-cerning the restoring of amateur transmit-ting facilities. The latest information tohand is as follows:-

Eire: The order prohibiting transmissionhas beén revoked and Eire's 53 pre-waramateurs are now permitted to operate.

Switzerland: Amateur transmitting equip-ment has been returned and ham activitieswere resumed on September 30th.

Colombian Republic: Governmentaldecree authorised amateur operation, sub-ject to pre-war regulations, from October9th.

U.S.S.R.: Activity on all amateur bandywas authorised on October 12th and contactswere not restricted to domestic limits.

Australia: Equipment has been returnedby the authorities and amateurs have beenreleased from their wartime silence.

Trinidad: VP4's may operate on any pre-war band (including 7 Mcs. phone) accord-ing to a report from VP4TI (via W2NYC) .

Brazil: Amateur operation has now beenre-established.

U.S.A. and Canada: Authorisation ofamateur activity on 28 Mcs. and higherfrequencies. A letter from Ed. Fraser,WIKQY, states that W's expect the returnof all bands early in the year.

And that is most of the information tohand at present, but next month, and insubsequent issues, we hope to be able togive more news as it is released fromauthoritative sources.

28 Mcs.: Although we are nowpassing through the " dead " periodof reception for this band, patient listeningwill bring forth quite good results andsome surprising DX catches. After Novem-ber 15th, the official day for the resump-tion of W and VE activity, and up toearly December, all districts of the U.S.A.,except the 7th were heard. All Canadiandistricts, except the 3rd and 4th were alsologged. It was quite common to log asmany as four dozen W's and a few VE's

between 1300 and 1700, particularly onSundays when the band teemed with signals.The most sought-after DX of the band, asfar as the W's were concerned, appearedto be EA1D (ex-W9JGQ in Madrid). Duringthe later part of December the band hasbeen very disappointing, often completelydead, with only a few weak carriers strug-gling through. It would seem that we mustwait until late Spring before the interestingDX possibilities of this band can be probedagain.

14 Mcs.: This band has provedmost enlightening and the least said aboutsome of the calls heard the better! Thosewith more likely sounding calls have beenPY7AD, 6AW, 7UD; HK1AB; U3AT;LU8EE; numerous HB9's, etc. U3CY wasalso heard, very clipped in his QSO's andgiving his QRA as " near Moscow " only.VK9XE was logged one day, but we donot feel very happy about his authenticity!Amongst the " probably genuine " calls,the following prefixes have been enteredin the log book: LA, F, OK, PA, I, LX,LZ, ON OZ, SM, OH and XU.

Doubtful stations have been TA1XA(shades of pre-war TA1AA!-Ed.), OY3C,ZC4NX, VQ4ZL, VQ4MIL, etc.

Portable: And with an accent on theP! In other words, have you heard W9VNDflitting around the Mediterranean? Here isa resumé of his activities on 14 Mcs. asrecorded here: He was first heard operatingunder the call of AR7VN, when he waslocated at Latika, Syria. After being QRTfor a few days, he re -appeared using thecall W9VND located at Haifa, Palestine.This was an Anglo-American stationoperated by W9VND himself (Oscar Jaeger)and G6ZY. After a few days the station,operating on phone/CW, was run entirelyby G6ZY. Later on, Oscar himself againappeared on the scene-this time using thecall ZC4VN. The latest mention in the logbook is when he appeared off Malta usingthe call ZBIVN! What's the betting thathe is now in Timbuctoo with the latestin callsigns! Incidentally, from the veryfirst QSO, 9VND has asked that all QSL'sbe sent to his Call Book address, all ofwhich will be answered when he reacheshome.

29

SHORT WAVE NEWS7 Mcs.: Well, to put it mildly, this

band is most certainly in need of a goodclean-up! We have broadcast stations, ser-vice stations and lastly, the most wonderfulcollection of pirates imaginable! Taking theprize for " spitch " are certain French" experimental stations," as they termthemselves, modulating well over 100 percent. with fatal results! Europeans, somemay be genuine, may be heard by the dozenand OZ, ON, LA, SM, EI, HB9, etc., haveall been heard. Some of the queer callshave been GD4AA, GC1AA and G9YL.

Have you heard YM7N calling CQ 40metre phone? If not, then you have missedthe opportunity of nostalgic memories ofthe North country, for 7N's fascinatingDanzig -cum -Yorkshire accent is a treat notto be missed!

3.5 Mcs.: Not much activity has beennoted on "80," although one or two stationshave made themselves heard through thesevere service QRM. PAOAF is about thebest signal, and various I, HB, OZ, ONand SM calls have been logged.

This page: The idea of this monthlyfeature is to present, in as interesting a formas possible, a cross-section of the month'slistening on the ham bands. Like mycolleague " Monitor," I must rely, to acertain extent, upon logs and commentscontributed by readers of the magazine. Weneed details of conditions, DX heard, tipson rare stations, notes on the QSL position,and so forth. It should be noted thatreaders should send their logs on a separatesheet of paper to any accompanying letter,with CW stations and phone stations listedseparately and preferably in alphabeticalorder of callsign. May we add that lengthylogs are not in themselves so very essentialunless they are accompanied by useful data.Incidentally, please record the times ofreception for out -standing " catches," and,if a member of any listening organisation,quote your identification number. Logs foreach ham band should also be listedseparately.

Please address all communications to:" CQ," 10 Orchard Lane, Pilgrims Hatch,Brentwood, Essex.

That is all for this month, and so vy73 and DX 1

Physical Society's Exhibition.The thirtieth Exhibition of Scientific

Instruments and Apparatus held by thePhysical Society at the Imperial College ofScience and Technology, South Kensington,London, on January 1st -3rd, must havebeen one of the best attended of any of thisSociety's excellent exhibitions. This year'sexhibition was simply packed with interest-ing equipment which was eagerly viewedby a great crowd of visitors. Radionaturally was well to the fore and someof the exhibits in this field were extremelyinteresting indeed. It would be quite impos-sible to do justice to this exhibition in theshort space available here, so we will con-tent ourselves with mentioning that to judgefrom enquiries made at some of the tradestalls, there would be no dearth of bothtransmitting and receiving valves suitablefor amateur use on the higher frequencies.Of particular interest to the amateur werethe range of quartz crystals for frequencycontrol units hermetically sealed in glasscontainers mounted on B7G type miniaturevalve bases, to be seen on at least two tradestalls. These crystals are quite suitable for14 Mcs. and one manufacturer's represen-

tative informed us that his firm were con-sidering marketing a suitable crystal of thistype for amateur use. A very nice aerialchange -over relay suitable for the amateurstation was also on show. We hope todescribe these pieces of equipment in detailin the near future.

Solution to Crossword No. 1.Across:

(1) Aerial. (4) Meters. (6) Anode. (7)Leaf. (9) Skip. (10) Electrons. (11)Yard. (13) Spar. (15) Storm.(16) Lamps. (18) Earth. (21) Bening.(23) Drill. (24 and 20) Apple -ton. (26)Tram. (28) Page. (30) Amplitude. (31)Mast. (32) Tube. (33) Rouse. (34 and32) Single -tube. (35) Spirit.Down:

(1) Alloy. (2) Layers. (3) Control.(4) Megohm. (5) Super. (9) SSS. (12and 35 across) Amateur -spirit. (14) An-tilog. (17) SOS. (18 and 8) End -fed.(22 with 26) Optimum -times. (24)Ampere. (25) Eludes. (26) Times. (27)Mat. (28) Pet. (29) Event.

30

SHORT WAVE NEWS

Receiver Types and Properties.Types

Receivers used for short-wave receptioncan be divided into three main groups, eachof which can be interpreted in many forms.They are (1) the Straight receiver, (2) theSuperheterodyne, and (3) the Super -Regenerative receiver. The actual circuitchosen will depend on the performancerequired, and this will vary according tothe individual, but in general performancecan be expressed as the efficiency of thereceiver in regard to certain functions.

Sensitivity

This is the ability of the receiver to detectradio signals and to render them intelligible,and is thus an expression of the overallamplification. It is given as the strengthof signal in microvolts which must beapplied to the aerial and earth terminalsof the receiver to produce a given audiooutput. The sensitivity will vary accordingto the frequency to which the set is tuned,and this frequency must therefore be speci-fied if the figure is to have any value,as also must be stated the audio outputfigure. This latter is usually taken as 50milliwatts where the output is fed into aloudspeaker, and a much lower value-ofthe order o! six milliwatts-where head-phones are employed. In the case of tele-phony, the input signal is assumed to be30 per cent. modulated by a pure sine waveof 400 cs. In the case of telegraphy, anoutput level of one or two milliwatts isoften chosen.

The modern " communications type "receiver often has a sensitivity of betterthan one microvolt, and is capable ofreceiving any signal greater than the in-herent receiver noise. When measuringsensitivity, the receiver controls should beset for maximum response and the injectedsignal applied through a standard " dummyaerial." This consists of a non -inductiveresistor of 400 ohms. for the short-wavebands, and for the medium and long wavesan inductor of 20 microhenries, a capacitorof 200 micro -micro -farads, and a resistorof 25 ohms., all in series.

Selectivity

The greater the sensitivity, the greater therequired selectivity i.e., the ability of thereceiver to reject unwanted signals. Thegreater the number of tuned circuits in a

receiver, the greater the selectivity, assum-ing a given selectivity for each tunedcircuit.

Selectivity is measured by injectingsignals of various frequencies on either sideof the frequency to which the receiver istuned, and measuring the voltage of thesignal required to give a constant outputin each case. In other words, the sensitivityis measured at various frequencies offresonance, and a curve is plotted fromthe figures so obtained. Fig. 1A shows atypical response curve taken from a super-heterodyne receiver with sharply peakedI.F. circuits, and Fig. 1B shows a curvefrom a similar type of receiver in whichthe I.F. circuits are " staggered," i.e., theyhave bandpass characteristics. It will beobserved that curve A, while possessingmuch better selective qualities than curve B,and from the point of view of reception ofCW on a crowded amateur band is thus thebetter, will be at a disadvantage if theincoming signal is suffering from frequencydrift, and will also be at a disadvantagein the matter of fidelity.

Fidelity

This refers to the relative ability of thereceiver to reproduce accurately the rangeof audio frequencies modulating the carrierbeing received. It can be indicated by acurve, drawn on a logarithmic scale, andshowing the decibel variation in outputwith a constant R.F. input modulated byvarious audio frequencies, the depth ofmodulation being reasonably constant. Itshould be notéd that the speaker used.or headphones, can have a profound effecton the results. Such a curve is shown atFig. 3.

Stability

The stability of a receiver is most impor-tant, being, in effect, the ability to remaintuned to resonance to any given signal ofconstant frequency. Apart from bad circuitdesign, bad stability can be caused 'by bothelectrical and mechanical faults. Stabilitywill be adversely affected by bad voltageregulation. " dry " joints, the wiring inR.F. circuits not being rigid enough, andso causing variations in circuit capacitances,by the use of components having high tem-perature co-efficients, by temperaturevariations, and inefficient screening amongother factors.

31

SHORT WAVE NEWS

I0,000

1,000

IOO

10

A

15 lO 5 0 5 10 15

kcs. off resonanceFIG. I.

B

FIG.2.C

80

60

20

SHORT WAVE NEWSSignal/Noise Ratio

Apart from external noise picked up bythe receiver, every set generates a certainamount which gives rise to a constant back-ground " hiss." However sensitive thereceiver, a signal is useless unless it can beread above the noise background, so thatthe signal to noise ratio, as it is termed,is an important factor, and especially soon the amateur bands where low powertransmission is general. Man-made static,such as car ignition interference, which con-sists of high amplitude peaks of very shortduration, can be greatly alleviated by theuse of noise limiter and suppressor cir-cuits. Atmospherics can be eased by the useof aerials having marked directional proper-ties, as, for example, the Bruce Inverted" V." Both forms of static cover a verywide frequency range, appearing in practiceto be untunable, so it is obvious that ifthe selectivity of the receiver can be madesuch that the bandwidth is sufficient onlyto pass the range of frequencies necessaryfor intelligible reception, then the staticreceived will be minimised accordingly, andthe ratio improved. The noise generated inthe set itself can be divided into two groups,the first including such items as mains hum,crackling, microphonic howling, excessivehiss from the beat frequency oscillator and/or mixer stage, etc. These faults can betraced to either bad design or faulty com-ponents. The second group consists oftwo items, the first being the noisedue to thermal agitation-that is, the move-ment of electrons in the various circuitscausing minute voltages to be set up-resulting in a constant background hiss.The second item arises in the valves and isknown as " shot effect." This is due tothe electron flow in the valve being irregu-lar, and can be dealt with only byimprovements in the design of valves. Itis useful to remember, though, that valveswith a high mutual conductance are usuallybest from the noise point of view. Dealingwith receiver noise, that generated in 'theinput stage is the most important, as herethe signal/noise ratio is at its worst.Summing up, the best signal/noise ratiowill be achieved by the use of as efficientan aerial/earth system as possible, coupledwith the use of high quality componentsand valves having low noise characteristicsin the input circuits of the receiver. '

Tuning RangeIt is not possible to cover the whole

frequency range required with a single L/Ccombination, as the variation in capacitancewould have to be excessive, and the tuningcorrespondingly sharp. The problem is over-come by having several ranges, with the

same tuning capacitor, or set of capacitors,being used on all ranges, and the coil orcoils varied according to the range in use.Commercially, the most favoured system isthat employing a switch, which inserts theappropriate inductors in circuit, often short-circuiting the remainder to prevent absorp-tion losses. In the cheaper receivers, theswitch is used to vary the inductance oftapped coils. The majority of amateursfavour the use of plug-in coils, which-though more unwieldy from the handlingaspect-has an advantage in that the cir-cuit wiring cate be cut to a minimum, result-ing in lower losses and an extension of thehigh frequency range covered with any giveninductor.

TuningEven with the smaller tuning capacitors

used in short-wave receivers, the frequencyrange covered by any one L/C combina-tion is much greater than the whole of themedium waves, and, tuning therefore iscorrespondingly more sharp. For ease oftuning, a slow-motion drive is essential,preferably one of the dual -ratio type, orhaving a flywheel incorporated so that ifnecessary the receiver can be quicklyswitched over from one end of a band tothe other. It is important that the driveused should not suffer from " backlash,"that is, slip in the motion causing thelogging point to vary according to thedirection of rotation of the tuning knob.

BandspreadUsually, the short-wave listener is

interested mainly in certain bands, eitherthe broadcasting bands or those allocatedto the amateur. More rarely, he is 'in-terested in both, but in any case it isobviously convenient, and results in easiertuning and logging, if it can be so arrangedthat the band in use at any one time isspread over as much as possible of thetuning dial. Fig. 2 shows three methodsof bandspreading, as it is called.

Fig. 2A illustrates the system mostcommonly employed. The circuit consistsof the inductor L tuned by Cl and C2 inparallel, Cl being the bandset capacitor of,normally, around 150 uuF and C2, thebandspread capacitor of some 15 to 25 uuF.The setting of Cl, plus the minimumcapacitance of C2 and the circuitcapacitance, will determine the maximumfrequency to which the circuit will tune.Similarly, the minimum frequency will bedecided by the additional capacitance whichcan be added to the circuit by setting C2at maximum capacitance. Unless specialinductors are used for each band, it willhe found in practice that the lower

33

SHORT WAVE NEWS

+25

+20

+15

+10

+5

15

20

2 S 40 60 100 2 3 4 5 1000 2

requency (cycles per sec)

FIG. 3.

frequency bands will occupy much morespace on the dial than the higher bands.

Fig. 2B shows an arrangement that isuseful when it is desired to get full spreadon the dial of, say, the amateur bands.One variable capacitor only is employedfor each tuned circuit, which disposes of theproblem of setting a bandset capacitoraccurately every time the band is changed.The inductor L and the padder C2, whichshould preferably be of the air dielectrictype, are built in one complete unit, withC3 added in the case of the lower frequencybands. The purpose of C3 is to obtain anLC ratio of such a value that these bandswill be confined to the dial coverage. Clis the tuning capacitor of some 100 to150 uuF.

Let us assume Cl to be 100 uuF maximumand 10 uuF minimum, with a circuitcapacitance of, say, 30 uuF. These two arein parallel, giving us 130 uuF maximumand 40 uuF minimum, which, in series withC2, will tune the inductor L. Supposewe require to spread the 7 Mcs. amateurband. If C2 is made 12 uuF, this willgive us an effective maximum capacitance ofa trifle under 11 uuF, and an effectiveminimum of 9.2 uuF. Using a 50 uHinductor, this will give an approximatecoverage of 6.8 to 7.4 Mcs., that is, theband will occupy roughly half the dial34

3 4 5 6 789

space. If C2 is made 10 uuF., themaximum and minimum capacitances willbe 9.3 and 8 uuF, respectively, and thecoverage with a 55 uH inductor will beroughly 7 to 7.5 Mcs., in other words, somethree -fifths of the dial will be occupied bythe band. With a little experimenting, itis possible to obtain almost full spread inthis manner.

The circuit shown at Fig. C2 will alsogive complete spread, but has a disadvan-tage, from the practical point of view, inthat the tapping point on the coil will haveto be determined by experiment. Cl is thebandset capacitor, and, here again, if certainbands only are contemplated, Cl can bemounted with the inductor to form acomplete unit, and can best be of the airdielectric type as used in high frequencyI.F. transformers. C2, the bandspreadcapacitor, is not critical regarding value,a suitable figure being around 50 to 100uuF. The actual amount of spread isdetermined by the position of the tap; thenearer it is to the bottom of the winding,the greater will be the spread.

Operating EfficiencyA point not brought up as often as it

might be is that any receiver, to give ofits best, must be efficiently handled, andthe controls, and their position, can domuch to help or hinder this. The majority

(Cont. on page 44)

SHORT WAVE NEWS

The Short Wave News All -dry

Frequency Meter.No listening station, or amateur transmit-

ting station, is or can be efficiently operatedunless it be equipped with an accuratemethod of frequency checking. Indeed, theG.P.O. insists, and rightly, that some formof frequency measurement is included in theapparatus employed in every licensedstation. From the transmitter's own pointof view, it is important that he be able todetermine the exact limits of the frequencybands allotted for his use, whether hisstation is operating within those limits,(especially when frequency doubling) thefrequency of any parasitic oscillations, andsuch matters.

The listener, too, cannot operate satis-factorily without some means of checkingthe coverage of his receiver. When reporting,it is seldom that the type of tuning scaleor dial fitted to most sets will allow ofan accurate frequency report being made,a most useful item of data to the trans-mitter operator should his signals be drift-ing, or outside the hand. It is also helpful

L

C2

7

Li

Al-/ti

C3

if he can be informed of the frequency ofany station causing interference with histransmission. Again, the receiver calibra-tion may be subject to alteration over aperiod through differences occurring in thetuned circuit constants, and the error thoughapparent, may not be readily measuredunless a frequency meter is available.

There are several types of frequencymeter, ranging from the simple job of in-different accuracy to the elaborate crystalcontrolled and stabilised frequency sub-standard of extreme accuracy. The cost ofconstruction varies accordingly.

The most simple form is the absorptionwavemeter, which consists of a tuned circuitloosely coupled to an indicating device. Inits most simple form the latter can be alamp connected across a small windinginductively coupled to the tuned circuit.When the latter is tuned to resonance witha source of RF, such as a reacting detectoror oscillator, the power absorbed causesthe lamp to light. The wavemeter can be

C6

Fig. 1. Theoretical circuit.

C7

CS

QHT t90v

OUTPUT

\I

I

QLTt/SvSI

QLTJ HT -

35

SHORT WAVE NEWS

Fig. 2. Coil details.

made more sensitive by employing a valve -voltmeter, or microammeter plus diode orcrystal rectifier as an indicator. The greatestadvantage of this form of frequency meteris that it gives indication of fundamentalfrequencies only, so that the problem ofconfusion over harmonics does not arise.The accuracy, however, from a calibratingpoint of view is poor, and therefore it isnot recommended for frequency measure-ment except for the purpose of identifyingany particular band of frequencies.

The crystal controlled sub -standard, ashas been stated, can be made exceptionallystable and capable of enabling frequencymeasurements to be made with an extremedegree of accuracy. Such an instrument,however, requires very careful constructionand handling, especially if a multi -vibratoris incorporated for frequency division, andis also expensive.

The S.W.N. frequency meter is of theelectron coupled type, and the theoreticalcircuit is shown at Fig. 1. Given the use

of good quality components, careful con-struction and ocrasional checking againstknown frequencies, which can be certaintransmitting stations where a standard isnot available, the heterodyne wavemeter iscapable of an accuracy of the order of0.05 to 0.1 per cent. It is in effect a smalltransmitter, working on a relatively lowfrequency, from which signals, either funda-mental or harmonics, are fed into a receiver.Any incoming signal of unknown frequencywill beat with the signal from the meter,producing an audio frequency signal in thereceiver output. When the wavemeter istuned correctly to resonance with the un-known signal, the receiver should indicatezero beat, that is, the silent point in thecentre of the two " side bands."

In order to obtain the greatest possibleaccuracy, there are certain points whichmust be borne in mind. The completewavemeter must be fitted in a screening case,to avoid stray coupling. Construction mustbe rigid and mechanically and electrically

36

SHORT WAVE NEWSsound, in order that the calibration remainconstant over long periods. The wavemetershould be free from frequency drift after theinitial warming -up period, which meanscareful design. The tuning dial must befree from backlash, and capable of beingread to fine limits. High grade insulatingmaterials only are permissible, and plug-intype coils are definitely not recommended.

Construction. The screening case andchassis employed in the frequency meterare built up from aluminium sheet, of 18swg material, and in order to avoid anydifficulty that may arise in bending up fromone strip, individual sides are cut out andfastened together by brass angle stripsbolted inside. A ready-made cabinet andchassis will probably be available by thetime this article appears in print. The casemeasures 8 inches high by 61 inches wideby 4} inches deep, and the chassis 6 inchesby 3 inches by 11 inches. These sizesshould be taken as minimum figures, andcan be enlarged where it is not essentialthat the meter occupy the smallest possiblespace. The chassis is fastened to the panelby four 4BA screws, and the unit built com-pletely on this with the exception of theoutput -terminal, which is mounted on thetop of the case. The back of the lattershould therefore be removable at will, inorder that the output lead, which is of stiff16 swg. tinned copper wire, can be con-nected to the terminal.

The position of the various components

is shown in Figs. 3 and 4. The layout isnot critical, but it is essential that heavygauge wire be used for the tuned circuitin order to avoid any possible movementand consequent change in calibration. Itmust be remembered, in this respect, thatthe leads from the coil to the filamentsockets on the valveholder form part of thetuned circuit. Care must be exercised whentightening the ceramic feed -through bushes,,or they may crack.

Floating components, such as tubularcapacitors, resistors, and the R.F. choke,must be wired in as firmly as possible, andthe length of the connecting wires kept toa minimum. A rubber grommet protectsthe flexible battery leads against chafing;where they pass through both the back ofthe chassis and the back of the cabinet.

The same considerations, as regards shortbut rigid wiring, apply above chassis. Itwill be noticed that a small trimmer isconnected across part of the coil, the pur-pose of this being to provide a means ofperiodically checking and adjusting the cali-bration of the meter against a station ofknown frequency. An opening must there-fore be made in the case opposite thistrimmer, through which can be passed theend of an insulated trimming tool.

Coil. The coil used in the frequencymeter is not a standard product, so willhave to be wound, but this is not a difficultprocedure. Full details are shown in Fig.2. It is not necessary that the tags onthe former be arranged exactly as drawn,

Fig. 3. Above -chassis layout.37

SHORT WAVE NEWSthis arrangement (Wearite " P " type)happening to be the original and to showclearly the connections. The gauge of wireand diameter of former should, however,be adhered to as closely as possible, anydeviation resulting in a change in the fre-quency range covered. It is best to startwinding by putting on section 1-2, this partbeing close -wound, i.e., adjacent turns'separated only by the enamel covering ofthe wire. Sections 2-3 and 4-5 are 'thenput on together, or interwound, that is,each turn of section 2-3 comes next to oneof Section 4-5. Any movement of the coilwould affect the stray capacitance and hencethe calibration, and the coil former musttherefore be rigidly fastened tp the chassis.This can be done by means of two smallbrackets, or by a cross -bar with a tappedhole and screw as shown in Fig.

Calibration. Before any attempt is madeat calibrating the instrument, it should beswitched on and left for a period in orderthat it may reach the maximum operatingtemperature. This also applies wheneverthe frequency meter is used for accuratefrequency measurement purposes, as duringthe initial warming -up period there is boundto be a certain amount of frequency drift.In the absence of a signal source of realaccuracy, calibration can be done by check-ing against radio stations, and for thispurpose a list is appended of selectedstations of known accuracy and frequency.A foot or two of wire connected to theoutput terminal is placed near to the re-ceiver aerial, and a station tuned in to

ClC2

C4C57.6C7RR2

250 uuF4-30 uuF0.05 uF100 uuF0.1 uF0.01 uF0.001 uF100.000 fl10.000 [i

RF ChokeValveholderCeramic BushesUtility DriveOn -Off SwitchValveGrommetsBattery

resonance on the receiver. The drive of thefrequency meter is then rotated until a beatnote is heard, i.e., the receiver sounds asif it is oscillating. It may be found thatthis effect can be obtained at more thanone setting of the meter dial, in which casethe setting should be chosen which givesthe loudest beat. As the frequency meteris tuned through the station, the beat notewill start at a high pitch, gradually becom-ing lower until a minimum-usually a silentpoint-is reached, and then rising in pitchagain. The zero point occurs when thefrequency meter is set to the exact frequencyof the station being received, and a noteshould be made of the meter dial setting atthis point. As many of these referencepoints should be obtained as possible, inorder to cancel out any inaccuracies thatmay arise. A calibration chart can now bedrawn up plotting the dial readings againstfrequencies.

The fundamental range using a coilexactly as described is from approximately1.6 to 5.6 Mcs., and harmonics allow thewhole frequency range from 1.6 to 30 Mcs.to be covered. It should be remembered,when calibrating, that the stations givenin the accompanying list will be operatingon frequencies that are in harmonic relationto the frequency which meter is setwhen the beat note is obtained. In somecases two, or more, settings of the dialwill produce a beat, but, knowing thefundamental range, these settings can beeasily separated into second, third andfourth harmonics.

THE COMPONENTS USED

Tuning Capacitor ...TrimmerFilament Bypass ...Grid CapacitorBattery Decoupling ...Screen DecouplingOutputGrid LeakScreen Feed

Cyldon S.L.F.Tele -Radio (1943) Ltd.T.C.C. 345.T.C.C. Man.K.T.C.C. 345.T.C.C. 345.T.C.C! Man.K.Dubilier.Dubilier.

Tele -Radio (1943) Ltd.Raymart VAS.Raymart.Raymart.Bulgin.Brimar 1N5GT.Tele -Radio (1943) Ltd.Ever Ready. All -Dry No. 3

or B.103.38

SHORT NAVE NEWS

Fig. 4. Under -chassis layout.

39

SHORT \VAVE NEWS

List of Stations for Calibration purposesFrequency

(Kcs)W/L

(Metres)Dial udll

Readings Sign Location22520 13.32 LSD4 Monte Grande21270 14.10 CEH3B Santiago21110 14.21 LSO8 Olivos,20980 14.30 WMY Brentwood20720 14.48 PPX Sepetiba20485 14.64 LQB6 Monte Grande20040 14.97 QTP Leopoldville19960 15.03 LCK Jeloy19850 15.11 ZBI9 Ascension Isle19660 15.26 SUS Abu Zabal19470 15.41 WDH Hicksville19260 15.58 PPU Sepetiba19180 15.64 CUS Lisbon19060 15.74 GLWG Dorchester18920 15.86 WQE Rocky Point18780 15.97 WMD Brentwood18690 16.05 ZEH Salisbury18480 16.23 HBH Geneva18298 16.40 YVR Maracay18150 16.53 HJO3 Bogota18000 16.67 WEQ Brentwood17860 16.80 WQC Rocky Point17685 16.96 GYJ6 Portsmouth17580 17.06 GYK23 Simonstown17480 17.16 OCQ2 Lima17320 17.32 VWF173/ Bombay

VWF817190 17.45 OXV Skamlebeak16940 17.71 NBA Panama Summit16740 17.92 SUX2 Abu Zabal16390 18.30 XGN Chungking16285 18.42 WKS Brentwood16130 18.60 FYX Lyons16000 18.75 WKQ Rocky Point15850 18.93 WCW Hicksville15760 19.04 WPE2 Rocky Point15675 19.14 WAE Brentwood15515 19.34 HDR Quito15455 19.41 FYJ Lyons15370 19.52 TN Cartago15100 19.87 EPB Teheran15020 19.97 GMX Dorchester14800 20.27 WQV Montevideo14915 20.11 CVO Rocky Point14695 20.41 WDU Brentwood14538 20.64 HBZ2 Geneva14415 20.81 GMR Ongar13980 21.46 LCO Jeloy13870 21.62 WIY New Brunswick13630 22.01 GIT Oxford13480 22.26 WAJ Rocky Point13255 22.63 OLI Prague13090 22.92 TAG Ankara12910 23.24 OXR Skainalebeak12820 23.40 RBP Moscow12695 23.63 SAG Goteborg12537 23.93 CUL Lisbon

40

SHORT WAVE NEWS

12235 24.52 TFJ Reykjavik12028 24.94 SDM6 Karlsborg11975 25.05 XOF Chungking11910 25.19 SUW Abu Zabal11692 25.66 PJS Curacao11625 25.81 ODE Beirut11480 26.13 PUO Marapicu11420 26.27 GLY Dorchester11200 ., 26.79 HBU3 Berne11000 27.27 CUK3 Lisbon10930 27.45 GLQ Ongar10820 27.73 WIX Brentwood10640 27.20 OZT Skamlebeak10480 28.63 WDY Brentwood10380 28.90 WCG Rocky Point10330 29.04 PSP Sepetiba10180 29.47 WJD Brentwood10090 29.73 WDK Rocky Point10048.5 29.86 ZFB Bermuda10000 30.00 WWV Washington

9965 30.11 FTL St. Assise9840 30.49 FYC2 Paris9800 30.61 LSD7 Monte Grande9742.5 30.79 LSA5 Monte Grande9450 31.75 WES Rocky Point9390 31.95 WCL Hicksville9213 32.56 GIV Oxford9060 33.11 GYJ Portsmouth8870 33.82 VWF3 Bombay8705 34.46 ZPZ Asuncion

HBM Berne8595 34.90 OXU Skamlebeak8455 35.48 CWF Cerrito8380 35.80 CUL Lisbon8310 36.10 RBO Moscow8185 36.65 PSK Marapicu8110 36.99 EPF Teheran8075 37.15 TYB2 Paris8005 37.48 GLK Dorchester7900 37.97 HER Berne7875 38.10 GNX Dorchester7797 38.48 HPB Geneva7625 39.34 WDQ Hicksville7415 40.46 WEG Rocky Point7365 40.73 GOW Dorchester6950 43.17 WKP Rocky Point6895 43.51 EDT S. Lorenzo6800 44.12 FYM2 Croix d'Hins6725 44.61 WQO Rocky Point6680 44.91 SUZ2 Abu Zabal6400 46.88 VIE Baghdad6276 47.80 SUP2 Abu Zabal5968 50.27 HVJ Vatican City5960 50.34. LCI Jeloy5905 50.80 WSY New York5835 51.41 LZD Sofia5732.5 52.33 SDB Motala5645 53.14 OXZ2 Lyngby5595 53.62 SAG Goteborg5410 55.45 ODP Beirut5355 56.02 WCF Hicksville5285 56.76 HBD Berne5250 57.14 WKT6 Brentwood

41

SHORT WAVE N E\\ S

Around the Broadcast Bands.Monthly survey by " Monitor "

All times are given in G.M.T.

Information please! Your scribe will bevery grateful for any notes and logs fromreaders. Please address all letters to:-" South View," Upper Drive, Angmering-on-Sea, Sussex. Remember, readers, thissection is for your benefit and only by acombined effort can we make it a com-prehensive review of the latest DX signalsheard. And now to my survey of themonth on the broadcast hands:-

AustralasiaThe Aussies continue to provide steady

DX signals in their broadcasts to Britain.The 0755-0825 session is heard over VLG3,Melbourne (11710 kcs.) , VLA6, Shepparton(15200 kcs.) and VLC2, Shepparton (9680kcs.) . The 1515-1545 programmes to GreatBritain remain as reported in last month'ssurvey.

Those of you who have never heardAustralia's famous Kookabura bird shouldtune in to VLA (7280 kcs.) , VLC6 (9615kcs.) or VLG (9580 kcs.) , from 1435-1445when the news to the Australian Forcesoverseas is opened by the song of this bird.This is really something worth hearing. Ifyou like something a little different, andmore difficult, have a try for the NorthAmerican service over VLR3 (11880 kcs.)at 0520 when they sign on with " WaltzingMatilda " followed by news in English.

News reaches me from diverse sources thatNew Zealand may soon blossom,forth with a10 kW transmitter on the 6, 9, 11 and 15Mcs. bands. However, at present the onlystation on the air is ZLT7, Wellington, on5715 kcs. with a power of 5 kW. Hasanyone heard it yet? The present position-e'garding the " Free Indonesian RadioStation " on 18140 kcs. (heard around1300) is not clear, and any information thatreaders can furnish will be muchppreciated.

Asia

No further development has been noted!rom " Headquarters Radio SEAC," signalshave still only been heard on 11845 kcs.India, through the vast array of AIRchannels, is still being heard well, one trans-mission regularly logged is the Burma beamfrom Delhi on 7300 kcs. at 1400-1500.

North America

Reception of the U.S.A. West Coaststations has no been as good duringthe past few weer,; as during the summermonths. However, a correspondent of mineheard KWIX, San Francisco, closing at1500 on 9570 kcs.-a good catch at thattime of the day.

The most reliable signal from Cubaremains COCX, " Emisora El Pueblo " on9295 kcs. (The station is officially listedas on 9273 kcs., although it would appearto be nearer 9295 kcs.-Ed.) . Others thathave been particularly noted, during thepast few weeks, are COKG, Santiago, 8955kcs., and COCQ, 8825 kcs., announcing as" CMQ Red Nacional " at 0400.

Across to the Dominican Republic and wefind HI1R, San Cristobal, pounding innightly on 6420 kcs. Is easily identifiedby call: " Broadcasting Nacional HI1R LaVoz de Santacion," and is at excellentstrength from 2300 onwards. Also heardabout the same time are HI9B, Santiago," Broadcasting Hotel Mercedes " on 6393kcs. and HI1N, Trujillo, on 6243 kcs.

Apart from TGWA, Guatemala is to thefore this month by the appearance of a newstation on about 7170 kcs. heard onnumerous occasions around 0330 giving thecall of " La Voz de la Libertad." Signs offat 0415. (This is TGNA, Guatemala City-Ed.) .If you haven't heard the difficult country ofMexico, note that XEWW on 9500 kcs. isstill putting out consistently strong signalsas mentioned in the January issue. XEFT,too, is still being received here. It is a250 watt short-wave outlet of XETF " LaVoz de Vera Cruz," and can be heard fromabout 0400 onwards-if you are lucky! Thestation verifies with a card giving the QRAas Indepencia Nó. 74, Vera Cruz.

Nicaragua is a country well heard,although it involves rather late hours!YNWW, " Radio Sport " on 7020 kcs.,YNBH, " Radio Panamerica " on 7010 kcs.and YNQ, " La Voz de la Victoria " on6915 kcs. have all been heard between thehours of 0000-0300. Roger Legge of Wash-ington, D.C., reports hearing a YNXW

42

SHORT WAVE NEWS" Radio America " on 7070 kcs. It may beas well to note that YNQ has until recentlybeen announcing as YNQW.

For consistent reception from Panama allhonours go to HP5K on 6005 kcs. An in-teresting programme is at 0315 in English.

'Uses the slogan of " La Voz de la Victor"and belongs to the Cadena Panamerica deRadiodifusion (network) and the QRA is

Apartado 33, Colon, Panama."

South America

Brazilian stations appear to be findingmuch favour in the 4 Mcs. band (60 metres)as recent listening on that band has re-vealed the following stations:-PRJ4,"Radio Educadora do Parnaiba," Parnaiba.4825 kcs.; PRC5, " Radio Clube do Para,"Belem, 4865 kcs.; PRF6, " Radio Bare,"Manaos, 4895 kcs. (Official slogan ofPRF6 is " Govern Del Estado doAmazones " but it appears that the shorterone is generally used-Ed.) . Other recentlyidentified Brazilians heard have been PRI3," Radio Inconfidencia," Belo Horizonte.6000 kcs. and PY2, Maceio Alagoas, 9310kcs. The latter station is an experimentalone and is on the air from 2300-0000," transmitting for the Stateall Brazil."

Excellent signals are received from theColombian Republic, especially from HJDE." La Voz de Antioquia,' ` Medellin on 6145kcs. It is best heard between 2300-0330,when it closes in English. Relays HJDKand belongs to the N.B.C. Pan Americannetwork. Bogota is well heard throughHJCD, 6160 kcs., and HJCT, 6200 kcs.

Dutch Guianá s PZX located at Para-maribo has been heard on occasions around0030-0130 with dance -music sessions onrecords, mainly of U.S. origin. Signalstrength is fair but a slight heterodyne issometimes noticed. Gives call on the hour,very indistinctly, but as Dutch is used thereshould be no trouble in identification. Signsoff, with Dutch anthem, at 0135.

Chile breaks into print this month by there -appearance of CE1174, " Emisora NuevoMundo," Santiago, 11740 kcs., inactive forsome time, but heard recently at 0220 withnews in Spanish. The well-known CE1180" Radio Sociedad Nacional," located atSantiago is still heard consistently althoughsignal strength has sadly diminished. Evenweaker, and more difficult to log, is " RadioEl Mercurio," CE1185, Santiago, 11850 kcs.,which has been heard occasionally. " LaVoz de Chile," CE970, at Valparaiso waslogged recently on 9728 kcs.-it has amarked carrier hum and suffers QRM from

the powerful " Radio Nacional," PRL7,which is only some 10 kcs. lower.

Peru is not too easy to hear at present,the famous OAX4Z has not appeared inmy log for some weeks now. A listen on6010 kcs. may reveal OAX4Q, " RadioVictoria," at Lima. It announces asOAX4X-OAX4Q and is audible from 0330.Usually QSA3 R6. Other Peruvians heardat odd times are OAX6E, Arequipa, "RadioContinental " and an OAX 4- (?) at Lima onabout 6420 kcs. (This is OAX4G, " RadioLima," on 6410 kcs.-Ed.) . Most Peru-vians are, unfortunately(!) at their bestbetween 0300 and 0500.

Salvador is definitely a rare country! Ifyou have the opportunity of listening around0315-0445, however, you may be fairly cer-tain of hearing this country on 6150 kcs.Call is given every 30 minutes, but exactletters are not yet known. (May be YSPB," La Voz de Cuscatlin "-Ed.) .

CXA19, Montevideo, is now operating on11835 kcs., and is probably one of theloudest regular Latin Americans. Identifi-cation is easy as the call is frequently givenas " Difusora El Espectador de Monte-video," CX19 y CXA19." Heard between2200-0300. CXA10, Montevideo on 11900kcs. is not quite so good, but may be quitea useful signal under favourable conditions.This one relays CX6 " Servicio Official deDifusion Radio Electrica." Readers mayalso look out for " Radio National deMontevideo," which is the slogan of CXA30operating on 6035 kcs. The call is givenevery 15 minutes and is preceded by asingle gong stroke.

Don't be misled if you hear the call" Radio Caracas " around 6200 kcs.-this isreally YV6RD, Cuidad Bolivar, which hasa habit of relaying YV5RN.

II Europe

There is not much new to hand thismonth froiñ this sector of the globe. PonteDelgada and PCJ appear to be still wellheard by most listeners. AFN London isa colossal signal on 8565 kcs. during theafternoon, but then it should be-the poweris 100 kW! AFN Paris on 6080 kcs. isalso putting out R9 signals from its 100 kWtransmitter.

The medium -wave " Emetteur NationalSottens " is now relayed on the short waves(6345 kcs.) ; The "Programme Nationale "of the Radiodiffusion Francais, is broadcaston short -waves (11885 and 9560 kcs. from1130-1300; 11885 and 9620 kcs. from1830-2100).

43

SHORT WAVE NEWS

Frequency Call Sign Location

4040 ERA Ponta Delgada4750 YVIRV Maracaibo4770 YVIRY Coro4775 HJGB Bucaramanga4780 YV4RO Valencia4785 HJAB Barranquilla

4790 YV6Rti Cuidad Bolivar4795 HJDX Medellin4800 YV1RX Maracaibo4805 HJDU Medellin4810 Saigon-

YV1RL4810 Maracaibo4825 PRJ4. Parnaiba4840 YV1RZ San Cristobal4830 YV2RN Valera4845 HJGF Bucaramanga4855 HJCA Bogota4860 YV5RU Caracas4865 PRC5 Belem4865 HJEX Cali4885 HJDP Medellin4890 YV5RM Caracas4895 PRF6 Mamas4915 ZOY Accra4920 YV5RN Caracas4930 HJAP Cartagena4945 HJCW Bogota4950 VQ7LO Nairobi4955 HJCQ Bogota4965 HJAE Cartagena

4975 HJAG Barranquilla4990 YV3RN Barquisimeto5000 WWV Belmont

(RECEIVER TYPES. --font. from page 34)of operators are right-handed, and use theright hand for writing, logging and keying.with the left hand doing most of the tuningoperations. Thus, the best position for thereceiver is on the left-hand side of thelistener, with the main controls, such astuning, audio gain, reaction, etc., nearesthis left hand. The more rarely used con-trols, such as tone, selectivity, band -switch,etc., could then be fitted to the other sideof the panel, subject, of course, to layoutconsiderations.

Examples of other small items that helpare the provision of extra headphone jacksfor visitors, a spare pencil ready sharpened.the keeping of proper log -sheets or book, anda station list amended as alterations arise.A little thought will suggest other pointsof a like nature.

BAND REVIEW.It is intended to " review " a particular frequency range each month, listing

only stations heard, in the hope that it may help you to identify and search for newsignals. This month we review the " 60 metre band," i.e., 4,000 kcs.-5,000 k-cs.The following stations have been recently logged by your scribe:-

Slogan

Emissora Regional Azores.Ecos del Zulia.Radio Coro.Radio Santander.La Voz de Carabobo.La Voz de Barranquilla y La Voz de

Victor.Ecos del Orinoco.Ecos de la Montana.Ondas del Lago.

Radio Saigon.Radio Populares.Radio Educadora do Parnaibo.La Voz de Tachira.Radio Valera.Radio Bucaramanga.

Ondas Populares.Radio Clube do Para.Radio Cali.Emisora Claridad.Radiodifusora Venezuela.Radio Bare.

Radio Caracas.Radio Colonial.Radio Compania de Bogota.

Radiodifusora Nacional de Colombia.La Voz de los Labortorias d.Colombia.Emisora Atlantico.Radio Barquisimeto.USA Frequency Standard.

Corrigendum--DENCO PRODUCTS. On page 21 of

the January issue of this magazine, thereappeared the following: " We are informedthat Denco products will be exclusivelydistributed by Messrs. Tele -Radio (1943)Ltd. of 177 Edgware Road, London, W.2."This statement is entirely incorrect, andshould have read " We are informed thatthese Denco products, etc.", referring ofcourse to the Mali -Q coils which were be-ing reviewed.

Denco products in general are beinghandled by a number of firms, includingMessrs. Berry's (Short Wave) Ltd. of 25High Holborn, London, W.C.1, to whomwe are indebted for pointing out this slip.

We apologise to Denco agents for anyinconvenience they may have been caused.

44

SHORT WAVE NEWS

The B.S.W.L. Multi -Range Meter.

Of all measuring instruments, the multi -range test meter is deservedly the mostpopular. The one described here will enablethe majority of circuit faults to be traced,and the cost of construction is not high.In order to get accurate readings when usedas a voltmeter it is necessary that themeter draws the minimum current, and themovement should therefore have a full scaledeflection of 1 mA or better. However, formost purposes a high degree of accuracy isnot required, so that the use of a movementwith a deflection of 2 mA or even 5 mAis permissible. With these, if an accuratereading is wanted, it can be obtained bymeasuring the total resistance in circuit,then the current flowing, and working outthe voltage by applying Ohms Law. Theaccuracy as an ammeter or as an ohm -meteris determined solely by the quality of theworkmanship.

The circuit is quite straightforward. Asan ammeter,' various shunts are connectedacross the meter on all ranges but one,the value of the shunt being such that onany one range, the meter passes at maxi-

mum its rated value, and the surplus currentis by-passed by the shunt. The formula forcalculating the required value of the shuntis

RmR n-1

where R .,is the required resistance, Em isthe resistance of the meter and n is thenumber of times the scale is to be extended.

As a voltmeter, on all ranges a resistoris placed in series with the meter acrossthe load to be measured, the value of theseries resistor being such that when on anyone range the maximum voltage for thatrange is applied, the resistor limits thecurrent flowing to a value equal to the fullscale deflection of the meter. Using the samenotations as before, the required value ofthe series resistor is given by R=Rm (n-1)in the case of an existing voltmeter, and by

R-f-Rm-Ex1000where E is the required full scale voltage,and I is the full scale deflection of Themeter in mA, in the case of a milliammeter.

THE B.S.W.L. MULTI -RANGE D.C. METER.

45

SHORT WAVE NEWS

As an ohm -meter, the meter is againemployed as a current reading instrument.The meter is inserted in series with abattery and a variable resistance, the latterbeing adjusted so that the meter reads full-scale when the test prods, also in series, areshorted. When the prods are placed acrossthe resistance to be measured, the metergives a lower reading due to the currentbeing limited by the extra resistance incircuit. For convenience, the scale is markedat points corresponding to the mA readingsthat would be given by cardinal values ofresistance placed across the prods. Thuswith- a 5mA meter, and 1.5 volts applied,the necessary resistance in circuit to give afull scale reading is 300 ohms. If the resis-tance to be measured has a value of 200ohms, then the total resistance in circuitbecomes 500 ohms, and the current flowingwill be limited to 3mA. Thus 3mA on thescale becomes synonymous with 200 ohms.On very low values of resistance, thearrangement so far described is not practi-cable, as the change in current flowing istoo small to be easily discernable. Thecurrent change can be made greater bymaking the initial resistance in circuit morecomparable with the resistance to bemeasured, and this can be achieved byplacing a shunt in parallel with the meterand variable resistor, the two latter beingstill in series. Thus, taking the examplealready given, to obtain a _ 10 range, theinitial resistance has to be reduced from300 to 30 ohms, i.e., the shunt will requireto have a value of 33.3 ohms. For a -r- 100range, the initial resistance becomes 3 ohms.and the shunt value 3.33 ohms.

The above dissertation is given in thebelief that the maximum benefit can beobtained from any instrument only whenthe method of operation, and not just theapplication, is understood.

CONSTRUCTION. No attempt is madeto lay down any hard and fast arrange-ments for layout, size and type of cabinet,or even what parts should be used, asthese matters are capable of a wide varietyof interpretation and so are best left tothe constructor concerned. The modelshown in the photograph was built in thelargest half of a suitcase portable rx cabinet,and the meter used was a six inch move-ment, with a full scale deflection of 5mA,simply because these happened to be onhand. The panel is of plywood, but couldequally well be of metal, paxolin, orebonite.

There is a wide variety of methods ofdealing with the selector dials. The onein the photo is of aluminium sheet, the

lining being cut with a scriber. The letter-ing is done by letter and number dies, andthe panel then rubbed over with emerypaper to remove sharp edges. Frosting isaccomplished by immersing the plate in astrong solution of soda, kept just on boilingpoint, for a few minutes. The blacking -inis then done by warming the panel, andrubbing in cobblers' heel -ball, or similarhard wax, the surplus being carefully re-moved with a piece of rag.

Ebonite and paxolin can also be stampedwith these dies, but are more tricky in thatthe amount of pressure used is much morecritical if a good appearance is to beachieved. Filling in is best done with thesematerials by means of white paint, prefer-ably paint which has gone almost hard.

Yet another method, and one capable ofgiving a near commercial finish, is to drawthe lining and lettering on tracing paper,using Indian ink. This is treated as anegative, and a photographic print madeon a bromide paper such as Kodak SnowWhite Royal, the result being similar tothe commercial engraved celluloid panels.After being glued to the sub -panel a coatof clear varnish is given to protect the sur-face from dampness, scratches, etc.

This does not exhaust the list by anymeans. Other methods, such as the useof white ivorine marked with Indian ink,and protected by a thin sheet of celluloidor perspex, will suggest themselves to thereader.

Coming now to the actual " works," thefollowing notes are given in the hope thatthey may prove useful to the non -technicalreader.

VOLTAGE RANGES. The best resistorsto use as multipliers are precision wire -wound types such as those made by Bulginand guaranteed to an accuracy of + .5 percent. In the absence of these, the ordinarystandard carbon resistors can be utilised.As normally sold, these have a tolerance offrom five per cent. to 20 per cent. plus orminus the nominal value. It is advisedthat the shopkeeper be asked to supplyresistors below the required value, they canthen be adjusted by filing carefully, until themeter reads correctly when connected acrossa known voltage. After filing, the resistorsshould be painted over to exclude damp-ness. When resistors can be obtained toa definite value, but the meter resistanceis unknown, this factor can be ignored with-out unduly affecting the accuracy, on allranges but tñe lowest, on which the requiredvalue will have to be found by trial. Onthe higher ranges, it is recommended thattwo or three resistors be used in series,

46

SHORT WAVE NEWS

THE ORIGINAL MODEL

3 any chance of high voltageg over " and damaging the move_

AMP RANGES. It is unlikely thatits for these ranges can be pur-ound to the correct value, but theyly be constructed by the reader.t wire to use from the stabilityview is Eureka. In order to avoidue to the shunts heating up and

value, the gauge of wire usedse ample to carry the necessaryIt is suggested that 36 swg. wire

for shunts up to 50 mA, 32 swg.[00 mA range, and 30 swg for the

250 mA range. The wire should be woundon paxolin strip formers, and the exactvalue arrived at by running solder alongthe wire. In the absence of Eureka,ordinary enamelled or silk covered copperwire can be used, but great accuracy can-not then be expected, as copper wire hasan appreciable temperature co -efficient, anda change of temperature of five degreesFahrenheit, apart from any heating due tothe current being passed, will affect theaccuracy by as much as one per cent. Ifcopper wire is used, the length needed willbe much greater than in the case of Eureka,so to avoid the possibilty of errors due toa magnetic field being created, and affect -

47

SHORT WAVE NEWSing the movement, the wire should be astati-cally wound on a bobbin. To do this, thenecessary amount of wire is wound on start-ing from the centre point, winding bothhalves together, so that both ends come onthe outside of the coil. Whichever methodis used, the shunts should be adjustedto the exact value by comparison with ameter of known accuracy, if possible! Fail-ing this, the meter should be connected inseries with a battery and variable resistor,the latter being adjusted so that the meterreads full scale. The shunt is then con-nected and adjusted until this reading occu-pies the correct place for the next range.Range two is then used to obtain rangethree, and so on.

OHMS RANGES. The variable resistorOR1 will be of low value, so the best typeto use is a wire -wound one with on -offswitch S3 combined. Switches 51 and S2should preferably be made for the job, suchas those marketed by Ferranti, Ltd., as anyresistance in the contacts will affectaccuracy, but as a substitute a good self-cleaning switch, such as the Yaxley pattern,can be used. Toggle switches, like thosein the photo, are a bad third, and shouldbe replaced at the first sign of erratic be-haviour. S2 is the X/-- switch, and shouldbe open when in the X position. The 1.5volt battery it controls must be capableof passing a heavy current, a matter of halfan ampere in the case of a 5mA movementand the Ever -Ready U14, as used in gas -lighters, is suggested. OR4 and OR5 mustalso be able to carry a heavy current with-out any appreciable heating, a suitable sizebeing 34 swg. for OR4 and 32 swg. for OR5.They should be wound on thin sheet paxolinformers, and be finally adjusted as follows.

A known resistor of a value that will givea mid -scale reading on the 10 range isused for checking. Again using the 5mAmeter for an example, this will be 30 ohms.The meter is then switched to the - 10range, the shunt applied, and the zero setOR1 adjusted. OR4 is then altered, eachtime re -setting OR1, until the pointer indi-cates 300 ohms on the dial. Finally OR5is similarly adjusted until a three ohm resis-tor also gives a pointer indication of 300ohms on the. dial, with the meter set to the

100 range. The 30 ohm and three ohmresistors can be lengths of Eureka measuredon the X1 and - 10 ranges respectively.

GENERAL. Range selection can bedone by either switches or plugs and sockets.Both methods are used commercially, andwhile the latter is perhaps not so convenientin use it does cause one to take more carethat the instrument is set to the correctrange. If switches are used, they shouldbe of a type having a very low contactresistance, especially in the case of the Milli -amps switch. Failing the types madespecially for this purpose, the Yaxleypattern is recommended. Note that S4 isganged to the Amps/Volts/Ohms selector,and should be closed when the latter is inthe Amps position, being open in the othertwo positions.

Unless one is used to it, it is not advisableto try to mark a resistance scale on theactual meter dial. Instead, it is suggestedthat a chart be drawn out, and mountedon the panel or else stored inside the batterycompartment, where it will not get mislaid.

On the X ranges, the 15 volts necessaryis obtained from two Grid Bias batteriesconnected in series, and care should betaken that the polarity is. correct.

Clues across: (1) Recast -anagram. (6)Pretty low ones, in the case of most G's.(9) Springs sometimes relieve it. (10)This power is pretty low. (11) It's on therecord. (12) His Christian name wasSamuel. (15) Ham these are held inpeace -time. (17) The owners of ZRH/ZRKetc.-abbrev. (20) Brand of resistor. (21)What the Ham does. (22) A signalgenerator would help to-this-your set.(23) What the " earth " should have.(24) These aerials are to be preferred.(25) The electron is an essential part of it.(27) The L.S. might incorporate one. (30)The paper for the workshop. (32) The endof the treasurer. (33) Many commercialstations send it. (35) With 29 down-Inthe past, not always the best " supplyhouse "-two words. (36) YL's., XYL's.,OM's., OB's., etc. (37) May be neces-

sitated by QRM. (38) You must knowthis for your licence.

Clues down: (2) Signal/noise? (3) Notnecessarily an inferior valve. (4) Your callmust be-with each QSO. (5) This in thewiring may mean no " sigs." (6) A powerone is useful. (7) This plug seems at aloose end? (8) What readers do in the" Around the Shacks " feature. (13) TheB.F.O. should not do this. (14) Usingspare components might not be-. (15)Part of the " Spout." (16) The beginnershould start on these circuits. (18) Triesout. (19) This eye is a tuning aid. (25)Current unit. (26) Old Rx cabinets wereoften-. (28) Not Dx on most bands. (29)See 35 across. (31) Unit of power -level.(33)What you do on a graph. (34) Onthe sun? [Correct Solution next month.

48

SHORT WAVE NEWS

HAM QUIZ.This month's quiz is of an historical

nature and should, if our guess is correct,prove fairly difficult. This quiz section issomewhat of an experiment and we wouldappreciate letters from readers giving theirreactions and suggestions for improvements.Please mark your correspondence " HamQuiz " c/o Short Wave News. In the mean-time, let us delve into the mists ofantiquity!

(1) Who was the first man to telegraphwithout wires connecting the trans-mitter and receiver, and in whatyear?

(2) When did Marconi first bridge theAtlantic?

(3) When was telephony first receivedfrom an aeroplane?

(4) When was the first cathode-ray tubemanufactured?

What amateur station carried theBBC Overseas Service on the shortwaves before the Daventry stationwas available?

(6) Who was the first man to " tele-phone " with the aid of Hertzianwaves, how far did he send, andin what year?Was the " bright emitter " intro-duced before the dull emitter?When and where was the lastInternational Amateur Conventionheld?In Humming's first '. carbon "microphone, what did he use inplace of the carbon granules usedtoday?

(10) Who was the first British ham tobridge the Atlantic on 5 metres?

(5)

(7)

(8)

(9)

RADIO CROSSWORD No. 2

i 1

9 ...J.4 . 0

. . .. 'o

'/ '5

III.

al

/2 .i3 i4 .....il ... /8 /9 20. 2/ ...u. ...:.....i laiil25 a.a... 3' J.

35 ....J 6.. JIll.

Answers to Quiz

(I) Morse, by induc-tion, in 1842.

(2) 1901.(3) 1915.(4) Commercially they

were first availablein 1900 (marketedby Messrs. Cos-sors). Early men-tions go as farback as 1870when Crookeswas experimentingwith them.

(5) G5SW at Chelms-ford, Essex.

(6) Dolbear, in 1886.Distance was 13miles.

(7) No.(8) Cairo, 1938.(9) Granules of finely

ground coke.(10) G5BY, Croydon.

THE S.W.N. 0-v-1 RECEIVER.

We must apologise for an error that creptin to the article describing this receiverin our last issue. In the theoretical circuit-Fig. 1 -the LT -lead should be shownconnected to that side of the switch SI,

which is joined to R6 and C9. The correctconnections are shown in Fig. 3. It seemsthat our Artist does not believe in LTswitches-he prefers to have the valvesalways warmed up ready for instant action!

49

SHORT WAVE NE\VS

Component Review.Belling & Lee, Ltd. It is surprising how

many commercial receivers, excepting theAC/DC types, are not fitted with any formof protection in the shape of a fuse. Weare afraid this is also too often true in thecase of home -built apparatus, though weare at a loss to give any reasonable explana-tion. Certainly, it can have nothing to dowith the cost.

We illustrate this month samples fromthe range of Belling Lee fuseholders. Fig.1 shows the type L.356 panel mountingholder, a very neat fitting which takes uplittle panel space, and has the advantageof instant accessibility. The contacts arecompletely insulated from the panel, andwhen the cap is removed-a coin slot isprovided for unscrewing-the fuse is ejectedby means of a spring. Connections are madeto soldering tags, and for fixing a $ inchdiameter hole is needed.

Fig. 2.

Fig. 2 illustrates the L.1033 Twin SafetyFuseholder. This is also a bakelite mould-ing, and is available as a single fuse modelwith the catalogue number L.1045. The

Fig. 1.

fuses are withdrawn with the cover,rendering the apparatus dead and enablingsafe replacement. Construction is the sameas pre-war, except for the addition of aspring clip to lock the cover in place.The unit takes 1 inch cartridge fuses.Connections are to screw sockets, and canbe brought in through the base or throughat either end. Type L.1291 is a recessedtwin model, which can be mounted almostflush on a panel. A rectangular hole isrequired for fixing, the unit being held inposition by a bracket supplied.

Fig. 3 shows the Belling Lee octal valvetop connector, type L.313/T. This is ofbrass construction, silvered to provide alow resistance path at high frequencies.Polystyrene is used throughout for insula-tion, and the use of a co -axial lead meansthat the self -capacitance is extremely low,making this connector ideal for high fre-quency work.

These components are priced as follows:Panel Fuseholder L.356, 2/6; Twin SafetyFuseholder L.1033, 4/-; Twin Safety Fuse -holder (semi recessed) L.1291, 4/6; SingleSafety Fuseholder L.1045, 2/9; Valve TopConnector L.313/T., 3/6.

ri

1\\\\\\\0\k\\ `°"\\ Fig. 3.

50

SHORT WAVE NEWS

DENCO COIL DATA.

Through the use of polystyrene formers, lower frequency ranges, the DENCO rangeiron dust cores, and Litz windings on the of Maxi -Q coils has the following features: -

High Q, with miniature size.Plug-in types fitting standard octal

holders, or Chassis mounting types withsingle 0 -BA fixing.

Adjustable cores simplifying receiveralignment.

A complete range covering 150 kcs. to 130Mcs., for straight or superhet receivers.

Less cores, the small size and short leadsobtainable make the formers very suitablefor VHF work.

RangeNominal InductanceMain Winding (core

at Maximum)

Frequency CoverageTuned by 300 uuF

(Circuit cap. 25 uuF)

Frequency CoverageTuned by 100 uoF

(Circuit cap. 15 uuF)

1

2

3

4

5

6

7

8

uH Mcs. Mcs. Mcs. Mcs.

2800 .175 .6285 .55 1.8 .85 2.632 1.6 5.7 2.5 7.34.4 4.4 15.0 7.0 20.01.0 9.7 32.0 15.0 40.0

Tuned by 50 uuF.0.5 30.0 60.00.2 50.0 90.00.1 72.0 130.0

As will be seen from the above chart,complete coverage of the long, medium andnormal short wave bands (10-1800 metresor 32-0.17 Mcs.) can be obtained with a300 uuF tuning capacitor. For best S.Wresults it is recommended that the totaltuning capacitance, including bandspreadand circuit capacitance, should not exceed110 uuF. Above 30 Mcs., this capacitanceshould not be more than 50 uuF, preferablyless.

The following colour code Is used toidentify the coils: -

BLUE: RF stage coils with aerial coup-ling.

YELLOW: Detector or Mixer coils, withcoupling winding which may be used forreaction, coupling fF stage or aerial.

GREEN: Detector coils with reaction andprimary windings for aperiodic aerial orRF stage coupling (6 pin) .

RED: Superhet oscillator coils. I.F to bestated (465 kcs. and 1.6 Mcs. available).

Plug-in coils are suffixed " P " andchassis mounting types " C." Thus a coilwould be described as, for example, BLUE4 C, meaning a chassis mounting type RFstage coil for range 4.

For a superhet receiver using these coils,a triode hexode of the 6K8 class should beused, in a conventional circuit (up to 30Mcs.) .

CONNECTIONS: Pins three and six, mainwinding; one and eight, Coupling or reac-tion (except some oscillator coils. Seebelow); four and five, Primary on 6 -pincoils.

Range 1. Oscillator coils. Padder to pin4, value 250 uuF.

Range 2. Oscillator coils. Padder to pin5, value 300 uuF.

Range 3. Oscillator coils. Padder to pin7, value 1800 uuF.

DIMENSIONS: Former diameter i".Overall height (less pins) 11". Basediameter, plug-in types 1".

51

t1OK"1' \V'AVIt; NE\VS

Small Advertisements.Readers' small advertisements will be accepted at 2d. pet word, minimum charge 3/.. Trade

advertisements will be accepted at 6d. per word, minimum charge 6/-. If a Box Number is required,an additional charge of 1/6 will be made. Terms: Cash with order. All copy must be in hand bythe 1st of the month for insertion in the following month's issue.

CLIFTON RADIO -34 Clifton Road.Maida Vale, W.9, can supply Belling Lee,Bulgin, Erie, Dubilier, T.C.C. components,B.V.A. valves and all amateur require-ments. Your enquiries welcomed. Call,write or phone CUN. 1436.

WANTED to complete volumes-QST forJanuary, February, June, July, August,1942, October, November and December,1943-Box 1001.

HOBBIES Imperial Fretmachine (largest).Perfect condition. Buyer collects. BSWI.1269, 86 Dibdin House, Maida Vale, Lon-don, \V.9.

ROTARY Duplicator for sale. Suit radioclub secretary, etc. £5 complete with ink,stencils, and other accessories.-Box 1002.

CALL BOOK wanted. State price, con-dition and issue to:-D. Small, 24 ThePaddocks, Wembley Park, Middlesex.

VHF fans: Turning, brazing and all typesof metal working. Send your requirementsfor quotation to: J. C. Wrankmore, 241Kilburn High Road, London, N.W.6.

SURPLUS to requirements. Various com-ponents, valves, materials, etc., goingcheap. Space wanted. Callers only (even-ings):-2ATV, 86 Dibdin House, MaidaVale, London, W.9.

FOR SALE: Perfex 35mm camera, per-fect. Coupled rangefinder, 1 to 1/1250 sec.,F2.8-£30. Required: A good reflex camerain perfect condition. No fancy priceswanted! Details to:-,A. Adams, 88 DibdinHouse, Maida Vale, London, W.9.

DUPLICATING and typing, to require-ments, at reasonable rates. Club secretaries-let me duplicate your news -sheets! Sendfor tariff of rates to:-H. Lister, 19 NewStreet, Pocklington, York.

RADIO SERVICE DEPOT is at your dis-posal! Large stocks of components, includ-ing many " sticky " valves. We supplyanything from a wander plug to a benchlamp. Send your enquiries-we may be ableto help you:-Radio Service Depot, SunnyCottage, Donnington Wood, Wellington.Salop.

AMATEUR RADIOPRODUCTS.

Designers and Manufacturers of short waveradio components and equipment. Coilwinding a speciality.Now available, Short Wave Coil Unit.Comprising 4 coils already wired andswitched, each coil consists of aerial, grid andreaction windings. The following are theranges with 160 mmfd. tuning condenser.

SWR I. 9.83 metres - 24 metres.SWR 2. 18.7 metres - 45.4 metres.

SWR 3. 38.4 metres - 95 metres.SWR 4. 92.3 metres - 206 metres.

Above Coil Unit complete with blue -print of2 valve (Battery) S.W. receiver for aboveUnit 30/-.Blue -prints for above, 1/6.Individual coils 3/3. each.Enquiries in first instance to :-

AMATEUR RADIO PRODUCTS50, GLASSLYN ROAD,

CROUCH END, LONDON, N.8.Phone :-Mountview -1745.

RADIO CAREERSAN IMPORTANT GUIDE" ENGINEERING OPPORTUNITIES " in-dicates clearly how all engaged in the Wirelessindustry can equip themselves for safe andhighly -paid posts despite the keener competitionwhich will come with a return to peace -timeconditions.This modern guide coatains 112 pages of highlyuseful information. It gives full details of ourvery comprehensive series of modem WIRE-LESS COURSES, including General WirelessShort Waves, Wireless and High Frequency,Talking Picture Engineering, Televisionand Radio Servicing, etc.TELEVISION AND RADIO SERVICING.There is no doubt about it that there will shortlybe an enormous boom in Television and unlimitedopportunities for the trained Serviceman. Ourspecial TELEVISION . and SERVICINGCourses are fully described in the handbook.

" ENGINEERING OPPORTUNITIES "also explains the most efficient way of preparingcandidates for such recognised Examinationsas A.M.I.E.E., A.M.Brit.I.R.E., City andGuilds, etc.

WE DEFINITELY GUARANTEE"NO PASS-NO FEE"

The Wireless industry is alive with possibilitiesfor the far-seeing man. In your own interestswe advise you to investigate these possibilitiesby sending for your copy of " ENGINEERINGOPPORTUNITIES " at once-FREE andwithout obligation.BRITISH INSTITUTE OF ENGINEERINGTECHNOLOGY, 816, Shakespeare House,

I7111i, Stratford Place, London, W.I.

Ill

SHORT WAVE NEWS

RADIO AMATEURENTIIUSIA STS

andW/T OPERATORS

The Candler System of Morse Code Train-ing has been demonstrating its value for the

past 34 years.

Each CANDLER SYSTEM Course (JUNIOR forBeginners-ADVANCED for Operators) is arranged ina series of 10 progressive lessons which are fascinating,instructive and practical. They teach you the mostvital principles of telegraphing technique, the funda-mentals of successful, efficient, accurate and speedy

Receiving and Sending of the Morse Code.Full details of the Candler System Courses in

MORSE COMETRAINING

are set out in the Candler "BOOK OF FACTS " whichwill be sent you post free and without obligation.

Courses supplied on Cash or Monthly payment terms.

THE CANDLER SYSTEM CO.Room 55 S.N.) 121 Kingaway, London, W.C.2

Candler System Co., Denver, Colorado, U.S.A.

THEPARTRIDGE

ORGANIZATIONis again at your service.

For six years we have been supplyingthe Services with our iron cored com-ponents. We are now once moreaccepting orders for ordinary commercialand domestic needs.

Our technical department will again bepleased to assist you in your transformerproblems.We look forward to hearing from ourold friends, and welcome enquiries fromnewcomers.

In return for a penny stamp we shall bepleased to send you details of our newstandard models with various styles ofmountings.

''.11krTelephone: Abbey2244

PARTRIDGETRANSFORMERS LTD76-8. PETTY FRANCE. LONDON, S.W.I.

C

THE

oar WAVE LEAGUEinvites all short wave enthusiasts to join a

live and progressive society.

The BSWL is a non-profit organisation founded to meetthe requirements of the short wave listener. Its aims are tofoster the Ham Spirit ; to bring together the SW enthusiastsof the world, through the medium of its Official Organ, tomutual benefit; and to provide these enthusiasts withfacilities for enjoying their hobby to its greatest extent.

Annual Subscription, 4/-.

DEPT. SW: BRITISH SHORT WAVE LEAGUE,53, MADELEY ROAD, EALING, LONDON, \V.5.

IV

SHORT WAVE NEWS

We are nowin a position

to undertakethe publicationof TradeCatalogues.Brochures. Des-criptive Folders.etc.

Send your requirementsfor quotation to :-

THE SHORT \VAVE PRESS,S7, Maida Vale, London, WV.9.

11d Jls CoShort -Wave Equipment

Noted for over 15 years forShort -Wave Receivers & Kits of quality.

One Valve Kit, Model " C " - Price 20/ -Two " E " - 43/-These kits are complete with all components,accessories, and full instructions. The prices

are inclusive of postage and packing.Send stamped addressed envelope for descriptive

catalogue.A. L. BACCHUS, 109, Hartington Rd., London.

S.W.8.

AMATEUR RADIO SIMPLY EXPLAINED

is a booklet invaluable to the newcomerto amateur radio and yet a good " buy "for those with many years of experienceto their credit. It contains chapters onThe Short Wave Listener, The AmateurTransmitter, Wartime Activities andFuture Prospects.ORDER YOUR COPY NOW FROM YOUR

LOCAL BOOKSELLER! Price 1/3.

Alternatively, send P.O. to BSWL StoresDepartment. 19 New S t r e e t,Pocklington, York.

1000's and 1000's

of "VERIES " andSWL/QSL CARDS

have been supplied for Hams inmany Countries by :

G6MNwho knows your requirements.

Printer of QSL'Ssince 1925

Send for Samples to :

G 6 M NCASTLEMOUNT,

WORKSOP, NOTTS.

THESE ARE IN STOCKTELEVISION RECEIVING EQUIPMENT.

By W. T. Cocking, A.M.I.E.E. 10/6. Postage4d.

RADIO LABORATORY HANDBOOK, 3rdEd. By M.G. Scroggie, B.S., A.M.I.E.E.12/6. Postage 4d.

TIME BASES SCANNING GENERATORS.By O. S. Puckle, M.I.E.E. 16/-. Postage 6d.

HIGH VACUUM TECHNIQUE. By J.Yarwood, M.Sc., A.Inst.P. 12/6. Postage 6d.

THE WIRELESS WORLD VALVE DATA-Operating Conditions and Base Connectionsof the Principal Types and Makes. 2/-.Postage 2(1.

VALVE REPLACEMENT MANUAL-ForRadio Service Engineers. By A. C. Farnelland Arthur Woffenden. 2nd Edition. 6/-.Postage 3d.

CATHODE-RAY OSCILLOGRAPHS. ByJ. H. Reyner. B.Sc.(Hons.), A.C.G.I. 8/6.Postage 4d.

THEORY OF ALTERNATING CURRENTWAVE FORMS. By P. Kemp, M.Sc.Tech.,M.I.E.E., A.I.Mech.E., M.A.I.E.E. 17/6.Postage 8d.

PROBLEMS IN RADIO ENGINEERING.By Radson, 5/-. Postage 4d.

SHORT WAVE RADIO. By J. H. Reyner,B.Sc.(Hons.). A.C.G.I. 10/6. Postage 4d.

AN INTRODUCTION TO THE THEORYAND DESIGN OF ELECTRIC WAVEFILTERS. By Scowen. 115/-. Postage, 4d.

THE DESIGN OF VALVE OSCILLATORS.By H. A. Thomas. 21/-. Postage, 6d.

Write or call for complete list, Id.

THE MODERN BOOK CO.(Dept S.1.) 18-23, PRAED STREET,

LONDON, W.2.

V

SHORT WAVE NEWS

SOLON ELECTRICINSULATIONSTRIPPER

SOLONELECTRICSOLDER POT

OLININDUSTRIAL

ELECTRIC APPLIANCES

SOLONELECTRICSOLDERINGIRONS

The SOLON Electric Soldering Ironillustrated is representative of a rangewhich includes models with varioustypes of bits suitable for a wide varietyof jobs. Usual standard voltages, alsofor low voltages ¡12v and 24v).The Insulation Stripper provides a quick methodof severing the insulation neatly withoutdamaging the conductor by means of an elec-trically heated wire.

The Solder Pot maintains 5 Ib. solder at workingtemperature.

If unobtainable locally, please write to the makers.

W. T. HENLEY'S TELEGRAPH WORKS CO., LTD., 51-53, Hatton Garden, London,E.C.1

TAYLOR A -C BRIDGEMODEL IIOA

These instruments give quick and accuratemeasurements of Capacity and Resistance.

There are six Capacity ranges covering from.00001 to 120 rnfd. and the Power factor canalso be measured on each range. Six

Resistance ranges are available measuringfrom I ohm to 12 megohms. This bridge isA.C. mains operated and a leakage test is

also available for detecting leaky paper ormica condensers.

Price L14 I4s. Od.

Please write for technical leaflet.

6RANGES OF CAPACITYRANGES OF RESISTANCE

Send your enquiries to:-

TAYLOR ELECTRICAL INSTRUMENTS LT0

'419.424 MONTROSE AVENUE, SLOUGH, BUCKSTc1; Slouch 21381 l4 Ines) 'Grams. "Taylins Slouch.

VI

» 1AS _ _ K

RANGECapacity Peak WorkingMfDS. VoltsSINGLE SECTIONS

I 500I (600 v. Surge)

32I 450

(550 v. Surge)100 250250 100500 50

I(CO 252000 12

CUPL SECTIONS8-8 ) 500

(6C0v. Surge)16-16 450

(550 v. Surge)32.24 350 v.

TRIPLE SECTIONS2-8-4 500

(600 v. Surge)16-16.8 450

(550 v. Surge)2C.2C-20 350 v.

We show above the range at presentstandordised in an aluminium canmeasuring 31 in. 11 in, fitted with5 -pin calve base. This list will beadded to from time to time, accordingto demand.

Plug-in ElectrolyticsFrom being the wayward child, the ElectrolyticCapacitor, as a result of continuous research and therigours of hard usage under years of active serviceconditions, has become the model offspring in thematter of reliability and efficiency.Even so, accidents must and will happen, and par-ticularly at public meetings and functions it is vitalto be able to locate and correct a cause of breakdowninstantly . . . . or even before it happens.It can be more than a mere inconvenience to haveto locate by test a defaulting capacitor, disconnectfrom the wiring and replace with a new one. Theadvent of the T.C.C. Plug-in Electrolytic reducessuch anxieties to almost nil and the replacementtime to a matter of seconds. It now takes no longerto replace than a valve.Although the present-day dependability of T.C.C.,

productions is such thatyou may never have to dothis, you should be pre-pared for the time .. .

WHEN SECONDS COUNT

CAPACITORS

London: Printed in Gt. Britain he Chas. Pearson & Son, Ltd., 53.55, Mansell St., London. E.1. for theProprietors, The Short Wave Press, 57 Maida Vale, Paddington, London, W.9. Obtainable through

W. H. Smith & Son. Ltd., and Tele -Radio (1943) Ltd.-February, 1946.