3 NEWS - RADIO and BROADCAST HISTORY library with

2 D-I-Y RADIO July-August 1996

Managing Editor: Mike Dennison; Production Editor: Jennifer Crocker; Tech Ed: Peter Dodd; Tech Illustrator: Bob Ryan; News Ed: Steve Lowe; Features Ed: Deniz Huseyin; Prod Asst: Wai-Yee Man; Secretary: Samantha Ralph.D-i-Y RADIO is published six times a year by the Radio Society of Great Britain, Lambda House, Cranborne Road, Potters Bar, Herts. Filmset by JJ Typographics Ltd. Printed by Southernprint(Web Offset) Ltd. © Radio Society of Great Britain, 1996. All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, or transmitted, in any form or by any means, electronic,mechanical, photocopying, recording or otherwise, without the prior written permission of the RSGB. All reasonable precautions are taken by the Radio Society to ensure that the advice and data given to ourreaders are reliable. We cannot however, guarantee it and we cannot accept legal responsibility for it. Prices quoted are those current as we go to press. ISSN No: 0959-843X.

CommentTHIS EDITION features the roleplayed by radio amateurs in help-ing to provide emergency com-munications. In these days of in-stant world-wide satellite com-munication and digital mobile tele-phones you would think that sim-ple amateur radio stations wouldbe of no use. But in an emer-gency, there is so much informa-tion to pass that the existing radioand telephone networks tend tooverload.

Amateurs are able to be flex-ible, too, changing site or provid-ing repeater stations in order toimprove coverage. Turn to pages10 - 13 to see some examples ofamateur radio providing this pub-lic service.

The various amateur organi-sations offering their help to theUser Services (Police, local coun-cils, etc) spend a great deal oftime carrying out exercises to trainfor ‘the real thing’. The picture onour cover shows communicationsbeing provided for a walkingevent; this serves to train theoperators in passing messagesaccurately and efficiently.

If you want to help to providethis type of public service, write tous and we’ll pass your details tothe nearest group.

Mike Dennison, G3XDVEditor

3 NEWSG0HZZ Helps Avert BlazeDisaster, AKD ‘Target’ NewListeners, Rising Stars, ANew LF Amateur Band,News in Brief.

4 HAMCLUB NEWSKey items of RSGB Newsfor HamClub Members.

5 CONSTRUCTIONSIMPLE DESKMICROPHONEHow to make a smart desk-top microphone by RobertSnary, G4OBE.

7 THE WHATS, WHYSAND WHEREFORESNUTS AND BOLTS ANDTHINGSJohn Case, GW4HWR, ex-plains how to recycle nutsand bolts from old equip-ment.

8 CONSTRUCTIONMORSE PRACTICEOSCILLATORSteve Ortmayer, G4RAW,shows how to build an audiooscillator with a pure, musi-cal note.

10 FEATURERADIO HELPS IN OILCLEAN-UPHow amateur radio opera-tors provided vital commu-nications links after the SeaEmpress oil spill.

12 POSTERAMATEUR RADIO TOTHE RESCUEAll over the world, amateursare using their radio skillsto help others in times ofdisaster.

14 REVIEWALINCO’S TINY UHFHANDIEWe take a look at the newAlinco DJ-S41, a low powerminiature 70cm transceiverwhich is great for Novices.

16 ON THE AIR2’S COMPANY,THE LOG BOOK,BAND BY BANDOur regular columns for thelistener and Novice licensee.Plus everything you need toknow about the 4 metreamateur band.

John Bowness, G7EFO, on the summitof Wansfell Mountain (482m abovesea level) providing communicationsfor an event organised by theWestmoreland & North Lancs Groupof the Long Distance Walkers’Association. John is a member of theSouth Lakeland Raynet Group whichcan provide efficient and flexiblecommunication in an emergencysituation. For more on emergencycommunication, see our poster andthe feature on page 10. Photo: TedBowness.

Robert Snary’s Desk Microphone (seepage 5).

The new AKD ‘Target’ receiver, tuned to 73kHz. See stories opposite.

18 FEATUREMEDIUM WAVEBROADCAST DXINGIan Poole, G3YWX, showsthat even a simple medium-wave radio can providehours of fun when you lookfor distant and unusual sta-tions.

20 CONSTRUCTIONA COMPACT50MHZ BEAMAn easy-to-build antenna forthe 6m band, giving gain anddirectivity. By Robert Snary,G4OBE.

18 LETTERS AND DIARYDetails of rallies and con-tests taking place during Julyand August.

47 PUZZLE PAGEWin a comprehensive elec-tronic constructors’ tool kitin this edition’s competition.Plus runners-up will win abeginner’s tool kit and a ra-dio construction video.

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3D-I-Y RADIO July-August 1996

NewsRSGB

Q U I C K -THINKINGN o r m a nC o a t h u p ,

G0HZZ, ensured that a blaze- 100 miles from his home -was swiftly quelled. Normanreceived a distress call froma radio amateur in Cumbriawho had seen a gas cylinderexplode near an isolatedcaravan site. The fire wasdangerously close towoodlands and vehicles.Norman, from South Wirral,called Ellesmere Port police,who faxed firefighters inCumbria. A fire enginearrived on the scene withinminutes and the blaze wasquickly brought undercontrol. Local police alsocaught youths suspected ofcausing the fire.

Norman said: “I’ve neverhad to do anything like thisbefore, but I am not going toboast about it. I was thenearest one to a phone so Idid what I had to do.”

G0HZZ Helps to AvertGas Blaze Disaster

AKD ‘TARGET’NEW LISTENERSAKD IS TO launch a seriesof communications receiverswhich they hope willrevolutionise the entry-levelamateur radio market. Thebasic model will be marketedunder the Target name andit is to be launched at a pricearound £160, including VAT.AKD hope that, at that price,it will encourage newcomersto short wave listening andamateur radio to buy theirfirst ‘serious’ communi-cations receiver.

The new radio is due outin September. It will cover30kHz to 30MHz in 1kHzsteps, with a clarifier controlso the user can tune betweenthe steps and resolve SSBsignals. Other versions ofthe receiver will be availablefor those who wish to receiveweather fax pictures, and forexisting SWLs and licensedamateurs who require ahigher specification receiver.An option on the ‘amateur’version will allow computercontrol and a spectrumdisplay on a PC screen.

SMC WILL BE holdingan Open Day on Saturday17 August at their ChandlersFord, Hampshire, HQ. Forfurther details, ring 01703255111

TO COMMEMORATEthe golden anniversary ofthe Irish Naval Service,special event station EI5INSwill be on the air during themonth of July from the IrishNaval Base on Haulbowlineisland in Cork harbour.

CY7TUB WILL BE onthe air from Nanaimo, BritishColumbia, 24 - 28 July tocelebrate the 30th anniver-sary of the ‘world famous’Nanaimo to Vancouverbathtub race!

RISING STARSAT A RECENT ‘crash course’ organised by STELAR(Science & Technology through Educational Links withAmateur Radio) at Kenwood Electronics UK Ltd, 20 teacherslearned enough about amateur radio to pass both papersin a mock examination. Five of them also gained a 100%pass in a mock Morse exam on the final day of the course.Thanks to this course, another 20 school radio clubs will beon the air in the near future.

LADY PLOWDEN, DBE, G6PHY, has agreed to be thePatron of STELAR.

A NEW LF AMATEUR BANDBRITISH FULL CLASS A licensees can request aNotice of Variation to allow them to operate on a newfrequency band at 71.6 - 74.4kHz. It’s in a part of theradio spectrum which until now had not been availablefor use by amateurs at all. The new band willappropriately be known as ‘the 73kHz band’ (‘73’ beinga Morse code abbreviation meaning ‘best regards’).

The new band comes about following several yearsof negotiation between the RSGB and the Radio-communications Agency, which allocates use of theradio spectrum in this country.

The 73kHz band is in the low frequency (LF) part ofthe spectrum, and its wavelength, about 4100 metres,is 25 times greater than that of the 1.8MHz band, untilnow the lowest frequency amateur band. A dipoleantenna for 73kHz would be over a mile long, althoughmuch traditional antenna theory is irrelevant at thiswavelength.

Norman Coathup, G0HZZ, at his station in South Wirral.

PHOTOGRAPH: COURTESY OF THE CHESTER CHRONICLE.

THE RA IS still settlingin to its new premises atNew King’s Beam House,so please continue to bepatient over the next fewmonths. They inform us thatrepeater and beacon licens-ing is now back on coursefollowing the bombing at theirDocklands headquartersand apologise to those whohave been kept waiting. Therepeater and beacon paperswere amongst the last itemsto be retrieved from theSouth Quay building afterthe bombing.


HamClub NewsRSGB

Key items of RSGBNews for HamClubMembers IAN SUART, GM4AUP,is acting as caretakerChairman of the RSGBExecutive Committee untilthe position is filled. SteveThompson, GW8GSQ, isthe new chairman of the VHFContest Committee, whilstthe new chairman of theMicrowave Committee isAndy Talbot, G4JNT.

ALL RSGB LiaisonOfficers (RLOs) must standfor re-election in September/ October 1996. Nominationforms are available fromeither the appropriate ZonalCouncil Member, RSGB HQor Chairman of theMembership LiaisonCommittee Ian Kyle,GI8AYZ. Completed formsmust be returned to the ZonalCouncil Member by 31 July.

THE RSGB WILL beholding amateur radio carboot sales at its Potters BarHQ from 10am to 4pm on 15July, 17 August, 21September and 19October. Books at bargainprices will be available onthe RSGB bookstall, andthere will be a raffle andrefreshments. There will bea charge of £5 per car,

payable on the gate (nobooking necessary), forthose wishing to sellequipment. The HQ buildingwill also be open (freeadmission), as is usual onthe third Saturday of eachmonth, with the GB3RSshack, National AmateurRadio Museum, and Libraryavailable to visitors. Morsetests are available ondemand between 11.00amand 12.30pm.

THE RSGB will have abookstall and membershipinformation stand at thefollowing rallies and events:4 August RSGB NationalMobile Rally, Woburn, Beds;18 August Red Rose Rally,Horwich, near Bolton; 18August Great Eastern Rally,Kings Lynn, Norfolk.

THE RSGB ISconducting an opinionsurvey on the future ofamateur radio . D-i-Y Radioreaders are invited toparticipate by writing to‘Survey Request’ at RSGBHQ in order to receive a copyof the survey form. Pleasenote that the completedsurveys should bereturned to IsisResearch Ltd (by29 July atthe latest)at theaddress

on the forms, and not toRSGB HQ.

NOMINATIONS AREwanted for several trophiesand awards. For the 1996Young Amateur of the Yearaward, contact MarciaBrimson, 2E1DAY, at RSGBHQ for full details and anomination form. The closingdate is 31 July. The G5RPTrophy is awarded to thenewcomer thought to havemade the most rapidprogress in HF DXing inthe recent past. Sendnominations to FredHandscombe, G4BWP,QTHR by 30 August. TheJack Wylie Trophy isawarded to the Scottishclub, society or RSGBmember thought to havedone most for amateur radiogenerally in the past year,and the Jock Kyle Trophyis awarded to the Scottishclub, society or RSGBmember thought to havedone most in Scotland in thefield of VHF in the past year.Nominations should be sentto Tom Menzies, GM1GEQ,QTHR by 14 August 1996.

A GB2CWslow Morse trans-

m i s s i o nfrom thestation ofGI3USK

is now being

broadcast on Sundaymornings at 11.00am on3600kHz.

THERE ARE vacanciesfor Senior NoviceInstructors in: South andEast Devon; North Devon;Gloucestershire; and theGlasgow, Kilmarnock,Motherwell and Paisley area.There are also vacanciesfor Novice Instructors inNorth Devon. Anyoneinterested in filling theseroles should get in touch withthe RSGB’s Co-ordinator,Phil Mayer, G0KKL, on01202 700903.

NEARLY A THOUSANDcandidates took the RSGBMorse Test, with a pass rateof 72.5 per cent, for the yearending 31 March. ChiefMorse Examiner RoyClayton, G4SSH, says thatthe five per cent increaseover the previous 12 monthswas due entirely to “a lastminute panic” by candidateswishing to obtain one of thelast G series callsigns beforethe change to M calls on 1April.

THE RSGB’s RepeaterManagement Group nowhas a new national Helplinephone number: 0956708873 available from9.00am to 9.00pm, sevendays a week.

Advertisement


Construction FeatureRSGB

Simple Desk Microphoneby RobertSnary, G4OBE

THE FIRST radioused by Novices,and others startingin amateur radio, is

often a handheld transceiver.The handheld is quite versatilein that it can be used in theshack as well as mobile.However, when used in theshack with an outside antennaa handheld can becomesomewhat awkward to use.

It can be more convenient touse a desk microphone. In thisarticle I have described the con-struction of a desk microphonethat can be used either withhandhelds which use a commonmicrophone and PTT line (suchas Icom, Rexon, ADI Kenproetc) or for sets where a separate‘push-to-talk’ line is used. Thedesign is very simple and usestwo plastic pen shells, the plasticlid of an old coffee jar (or similar)and the plastic case of a ‘DIN’plug. The overall design isshown in the photograph onpage 2.

CONSTRUCTIONTHE END-CAP AND the inktube/ball point should becarefully removed from the penand discarded, leaving only theclear plastic shell.

One of the pen shells is usedto make the vertical support forthe microphone and the other isused to hold the microphoneelement.

The body for the verticalsupport should have thepointed end shaped so thatthe microphone support is setat a convenient angle (see Fig1).

The base should be preparednext (see Fig 2). Four holes arerequired, two (‘A’ and ‘B’) aresmall holes for cable to be fedthrough and a third slightly largerhole, ‘C’, which is used to takeone of the plastic end caps fromthe pen bodies. The fourth hole,‘D’, is dependent on the type ofswitch that you use for the pushto talk (PTT).

Some epoxy resin such as‘Araldite Rapid’ is used to fastenall the bits together. Only asmall amount at a time shouldbe mixed as it is best toassemble the base, piece bypiece and let the glue hardenbefore moving on to the nextpart of the assembly. Theinstructions and warnings on theglue must be followed toprevent any accidents.

The first item to be glued intoplace is the plastic end from thepen body and this is passedthrough hole ‘C’ underneath the

lid (see Fig 3) . Then the shapedpen body is placed over thispiece and glued in place as thevertical support. While the glueis setting you can place the DINplug body on to the second pen.

Once the resin has set for thevertical support you can thenglue the second pen body inplace, making sure that theassembly is supported until theglue has set. A side view isshown in Fig 3. The microphoneassembly should be left for 24hours before completing theelectronics side of the projectso that all the glue is properlyset.

Any type of switch which hasa ‘press-to-make’ contact canbe used, the only recommen-dation that I would make is touse a switch which does notrequire a great deal of pressureto operate so that it does notbecome too uncomfortable topress during a long trans-mission.

If you find that the micro-

Fig 1: Vertical support made from ball-point pen shell.

Fig 2: The microphone stand base.

Fig 3: Complete microphone stand assembly.

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COMPONENTSResistors

R1 (Fig 4) 33kΩ 0.25 Watt CarbonR1 (Fig 5) 1kΩ 0.25 Watt Carbon

Capacitors

C1 (Fig 4) 0.1 µF Ceramic Disc CapacitorC1 (Fig 5) 0.1 µF Ceramic Disc CapacitorC2 (Fig 5) 10 µF Sub-miniature Electrolytic Capacitor

Additional Items

S1 Push to Make SwitchElectret-Condenser Microphone Element Maplin Type FS34WScreened CableMicrophone Plug Suitable for your set.Small Piece of Veroboard If requiredScreened CablePP3 Battery and Battery Clip if a suitable supply voltage

is not available from theset.

Microphone Plug Suitable for your set.Two Old Plastic Ball Point Pen shellsPlastic Coffee Jar LidPlastic Body from DIN PlugAraldite Rapid or Similar Epoxy Resin Glue

phone is too light and slidesround your operating desk thenyou can use some plasticine inthe base.

CIRCUITDESCRIPTIONA SMALL ELECTRET con-denser element is used, whichneeds to be powered by a DCsupply.

Most handheld sets use asingle screened lead for boththe PTT line and the microphoneaudio lead. The diagram of thewiring for a handheld in Fig 4shows that the microphone isconnected via screened cableto a resistor R1 and capacitorC1 and then the press-to-talkswitch S1 to the set.

If you find that the set will nottransmit when the PTT switch ispressed reduce the value of R1to 27kΩ. The value of R1 in Fig4 is suitable for the Icom, Rexonand ADI Kenpro transceiversthat it was tried with, but mayhave to be reduced for Yaesusets.

For radios which use separate

PTT lines the circuit in Fig 5can be used. A suitable supplyis needed for the microphoneand this must not exceed 9 volts.This can be derived from a PP3type battery or from the set.Some modern sets have asuitable supply voltage availableon one of the microphone socketpins, (see the handbook fordetails)

The PTT switch is shown inthe diagram as being connectedin a ‘ground-to-transmit’operation but some ex-PMRsets use a different type ofarrangement. Again, I wouldrecommend that you check inthe handbook for your set.

The microphone elementshould be connected to a lengthof screened cable. Insulatingtape can then be wrappedaround the microphone insertso that its diameter is increasedand it makes a tight fit into theDIN plug cover. The screenedwire should be taken throughthe pen body and into hole ‘B’.The wiring for the fewcomponents can either be madedirectly on to the switch used for

the PTT or on to a small piece ofVeroboard. To a certain extentthis is determined by the type ofswitch that you use.

The final length of screenedlead goes from the microphonevia hole ‘A’ to the transceiver.This requires a suitable plug foryour set.

ASSISTANCEAVAILABLETHE PROTOTYPE micro-phones have been used with avariety of sets, but I wouldrecommend that beforeconnecting the microphone youcheck in the instruction manualregarding connections. If youhave any questions I would bemore than willing to try and help.All I ask is for the queries to bein writing, with a self-addressedstamped envelope and aphotocopy or sketch of anyrelevant information from theset's user’s guide.

My address is: 12 BordenAvenue, Enfield, Middx, EN12B2.

Fig 4: Wiring diagram for handheld radios.

Fig 5: Wiring diagram for radios which use separate PTT lines.

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RSGB The Whats, Whys, and Wherefores

Nuts and Bolts and Things

By John,GW4HWR,Chairman

RSGB Training& EducationCommittee

WHEN EVER YOUdecide to makesome piece ofelectrical equip-

ment (simple or complex) nutsand bolts are very likely to beneeded. If they are purchasedthe price can be very high so tryto set up a store of your own bya process of recycling!

CHEAP SOURCEMANY REDUNDANT items ofequipment are held together bynuts and bolts, so never consignany item to the bin beforechecking to see if there are anybits worth saving. Old taperecorders, Hi-Fi units, televisionand radio receivers are all likelyto be full of useful small piecesincluding - nuts and screws.

TOOLSTO HELP IN their removal ascrewdriver with a blade groundas shown in Fig 1 is mostsuitable. This shape is chosenso that the screwdriver doesn’tjump out of the slot in the screwas would probably happen if theblade had a shape like thoseshown in Fig 2 . In addition tothe possibility of the slippingscrewdriver causing damage to

some other component, the slotof the screw will be deformedand the difficulty of turninggreatly increased. A small pairof pliers will also be needed,they should have jaws whichare serrated and not bent.

Another excellent source isex-service equipment but thereis one major snag. To ensurethat the many nuts and screwsdo not work loose with theconstant vibration met in mostservice environments, each oneis sealed with a varnish. Thisusually appears as a red or bluecoating and if present will makeremoval of the nuts almostimpossible. However like mostvarnishes, almost all will softenwith repeated application ofmethylated spirit. Use a cottonbud and dab a little on each nut,it takes a little time to work so bepatient and go round the nutsyou intend to remove, severaltimes. Stubborn ones willprobably respond to a little heatfrom a soldering iron but takecare. Don’t waste too much timeon one screw!

Make a start on the mosteasily accessible screws first,don’t worry about the size, eventhe bigger ones will come inuseful sooner or later. It is useful

to have a number of small boxesavailable to store your loot, for astart the round plastic boxesfrom used 35mm films will dobut you will findthat bigger sizesare needed quitequickly. DIY

Fig 1: In an ideal world dimensions X and Y would just fit the slot of the screw.

Fig 2: A screwdriver with a blade shapes as shown will tend to jumpout of the slot in the screw when the blade is turned.

Fig 3: Some of the more common types of screws which can be foundwhen dismantling surplus equipment.

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Morse Practice Oscillatorby SteveOrtmayer,G4RAW

NOT ANOTHERMorse practiceoscillator you willprobably say.

Well yes, but this one is ratherdifferent.

Most of the Morse practiceoscillators that have beendescribed before produce a non-sinusoidal waveform, ie asquare wave or a triangularshaped waveform. The soundfrom such an oscillator tends tobe harsh and raspy. A sinusoidaloscillator gives a sound thathas a pure musical note.

THE TWIN TEEOSCILLATORTHE BASIC REQUIREMENTSof a sinusoidal waveform(sinewave) oscillator is anamplifier and a feedbacknetwork. This network isnecessary so that some of theoutput from the amplifier is fedback to the input to maintainoscillation at one frequency.

The circuit used in thisproject, see Fig 1 , uses a BC109(TR1) as the amplifier. Theoscillator circuit is called a TwinTee, because it uses two ‘T’

filters in parallel in the feedbackpath. The frequency at whichthe circuit operates is deter-mined by the values of theresistors and capacitors in the‘T’ networks.

The output from the oscillatoris then amplified, by an LM386integrated circuit audio amplifier,to drive the loudspeaker.

CONSTRUCTIONTHE PROJECT IS constructedon plain perforated board (boardwithout the copper strips) asshown in Fig 2. The componentsare supported by bending theirconnecting wires under theboard. A common groundconnection is made by solderinga length of wire between twosolder tags.

It is a good idea to build theloudspeaker amplifier first andto use an IC holder for IC1, theLM386 amplifier. Connect theloudspeaker then the 9 voltbattery. Touch the input (pin 3)of the amplifier with a ‘probe’made from bare copper wire; ifthe amplifier is working abuzzing noise will be heard inthe loudspeaker. If the amplifier

COMPONENTSResistors -1/4 watt carbon filmR1, R2 18k,R3 4k7R4 10kR5 10R

CapacitorsC1,C2 10nFC3,C8 47nFC4 100nFC5 22nFC6 10µF, 16v electrolyticC7 22µF, 16v electrolyticC9 220µF, 16v electrolytic

SemiconductorsTR1 BC109IC1 LM386

Other ItemsRV1 10k log pot with switch8 ohm loudspeakerPerforated board 3.5 x 9cmKey socket to suit your key (noteit takes 9V)Box or case

Fig 1: Circuit diagram of the sinewave oscillator and amplifier.

does not work check theconnections and try again.

Once the amplifier is workingit can be used to test theoscillator. Build the oscillatorcircuit and connect the output tothe amplifier. Set the potentio-meter RV1 to the halfway

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RSGB The Whats, Whys, and Wherefores

stores sell plasticcabinets of drawerswhich are verysuitable for strong

components, includung nutsand bolts.

There are other items ofhardware which are worthsaving, spacers of many sizes(these are tubular pieces ofmetal between 5 and 50mm,with either a plain or threadedhole through the centre),washers - plain and serrated(shake proof), threaded rodsand solder tags. All will come inuseful later.

VARIETYYOU MAY HAVE noticed that inparagraph two the words ‘nutsand screws’ were used whereasthe title referred to ‘bolts’.Screws are threaded along thewhole length whereas bolts havea plain unthreaded length belowthe head, also, bolts will have a

square or hexagonal head (foruse with a spanner) whilescrews have a slot or a crosspoint. You will also find a varietyof different shapes of head.Some of the more commontypes are shown in Fig 3.

It is important to note thatthere are different threads forscrews and nuts whichsometimes prevents the twoitems fitting together. It is goodpractice (at least until thedifferent types can berecognised) to run the nuts onto the screw from which theywere removed. There are twomain types in common use,these are called imperial whichare given numbers such as 6BAor 4BA depending on thediameter of the screw and ISOmetric , where the names are inthe form M2.0 or M2.5 wherethe numbers indicate thediameter of the thread inmillimetres.

Fig 4: A guage used to compare a range of Imperial and Metricscrews.

SCREW GAUGEA GAUGE USED to compare arange of these two types ofscrews is shown in Fig 4. Youcan use it to measure the screwdiameter by noting where thescrew touches the sides of theV shaped slot.

The effort of recyclinghardware described in thisarticle can reduce the cost ofprojects and will often provide aparticular piece which no retailerseems able to supply.

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Fig 2: Component layout and interconnection diagram.

position. Connect 9 volts directlyto the amplifier and the oscillator;the oscillator tone should beheard in the loudspeaker. Thevolume can be adjusted withRV1. The tone can be changedby altering the component

values around TR1; tryexperimenting and note whichvalues cause the changes intone.

The key socket carries 9 volts,so it must be either plastic orinsulated from a metal case. I

used a 10k log potentiometerfor RV1 with an ON / OFF switch,but you could use a separateswitch.

The project is now completeand can be housed in a box ofyour choice.

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Construction Feature


News FeatureRSGB

“OIL SLICKS fromthe Sea Empresshave spread intoCarmarthen Bay.

Tenby, Saundersfoot, Amroth,Wiseman’s Bridge and Pendineare all affected. The emergencyservices are working day andnight along the coastline.Communications are weak andurgently need strengthening.Raynet have asked us for helpand CPPU would appreciate thesupport.” So went the telephonecall from Islwyn Hughes,GW4ZXL. “How are you fixedfor mobile work?”

I have an Alinco DJ-580 dual-bander giving a maximum of5W if used from the car battery.Would that be sufficient?GW4ZXL thought it would. WasI prepared to help? No questionabout that - I was retired andalthough I had commitments Icould organise my availability.But what about frequencies,procedure, coping underpressure? I’m a real amateur,and a new one at that - no yearsat sea as a radio officer orintensive training at the RAFSchool of Radio.

The frequency question wassolved immediately. “Use S9 on2m and 433.700 on 70cm.” Asfor the rest, well time would tell.Finally, “Bring something to eat- it could be a long day”.

ON CALLTHE FOLLOWING morning,from near St Clears, I was ableto monitor the controller on 2m.There was constant radio trafficand it was obvious that therewas considerable activity allalong the coast. At Pendine Isaw some JCBs working on thebeach. On Marros Hill I seizeda pause in transmissions toannounce myself, hoping myhandheld would proveadequate: “GW0UMC Mobilecalling Oil Spill Control.Reporting in. The name is

Granville. GW4ZXLis expecting me. Doyou copy?”

“GW0UMC Mobilefrom GW3IGGMobile. WelcomeGranville and thanksfor coming. Islwyn,GW4ZXL, will meetyou at Amroth andbrief you. Pleaseconfirm.”

“ C o n f i r m e d ,GW0UMC Mobileclear”.

My first contact on

the emergency channel duringa recognised national disaster.I was working with the big boysnow!

Islwyn met me at Amroth andgave me a list of the locations inour area east of Milford wherecleaning operations were in fullswing. In practically all of thesefrom Freshwater East toPendine, amateur radiooperators were providing theessential communication link.

John Jones, GW3IGG,Forward Control (Fig 1) , waslocated at Monkstone Point andhe was co-ordinating the trafficfrom there. His carefully chosenlocation accounted for theexcellent signal and I was ableto make contact from all thebeaches I worked.

When he later moved to theRidgeway at Penally, to enablebetter contact with the JointResponse Control at the PortAuthority at Milford Haven, therewere some voids in the traffic.For me, one of these wasSaundersfoot and I found itnecessary to make contact viaa relay station at Wiseman’s

Radio Helps in Oil Clean-upby GranvilleBowen,GW0UMC

Forward control, GW3IGG/M, on the Ridgeway. L to R: Joe Neal, SWL; John Jones,GW3IGG; and Alan Dicker, GW3VEN.

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Fig 1: Network diagram throwing the communications link established during the oilspill clean-up operation. GW3IGG/M was located at Forward control.


News FeatureRSGB

Bridge where GW8BKL waslocated. Later, afterexperimenting, I found a spotwhere contact was just possible,but generally the locals referredto Saundersfoot as a “hole”, aradio hole, that is!

TOUR OF DUTYMY BRIEF, on this my first tourof duty, was to relieve GW0TSFat Wiseman’s Bridge; thencontact the Beachmaster toestablish a firm communicationsliaison. Wiseman’s Bridge wasa hive of activity so contactingthe Beachmaster was not goingto be easy. I later realised hewas responsible for threebeaches and could be on anyone of them.

At Wiseman’s Bridge, thebeach, shingle and cliff facewere all dotted with men,machinery, hoses, and variousunidentifiable (to me) pieces ofequipment. Each group Iapproached knew he wassomewhere; but not there!Evidence of the oil spill waseverywhere. A long stretch ofshingle, interspersed with largeblack globules, lookedparticularly unpleasant, as didthe areas of soaked sand. But itwas the cliff face that wasproving particularly obstinateand defying the efforts of themen to power-wash off the oilresidue.

Here I found him. Hisprotective clothing was oil-stained and he looked strainedand under pressure. He wasundoubtedly pleased to see me.His mobile phone had beenmalfunctioning for two days andhe had a list of requirements,one of which was, “Can you doanything about food? Some ofthe men have been here sinceearly morning.”

I waited for a break in theradio traffic and called GW3IGGwith my list of requirements.When it came to the request forfood, I was told that the WRVSwere travelling along the coastroad and providing sustenance,but at that stage communi-cations were tenuous and therewas no ETA. Then the Gods

THE SEA EMPRESS oil spill on the beaches ofsouth-west Wales back in February provided groupsof radio amateurs with a chance to display theircommunications skills. They played a vital role in theclean-up operation, as Granville Bowen, GW0UMC,describes.

Dyfed County Council called out Raynet onWednesday 28 February 1996. Operations beganthe following day and continued until stand-down onThursday 21 March.

Three amateur radio organisations were involved:Pembrokeshire Raynet (group controller GW3IGG),North Dyfed Raynet (group controller GW1XOT),and CARSET (Carmarthen Amateur Radio SocietyEmergency Team, secretary GW4ZXL).

We are grateful to John Jones, GW3IGG,Pembrokeshire Raynet group controller, for providingthe background information, diagram andphotographs for this article.

Now turn to the poster in the centre of this issueof D-i-Y Radio for more on how radio amateurs cometo the rescue in times of emergency.

Beach clean-up vehiclesand men in action.

stepped in: around the cornercame the WRVS with ham rolls,tea, coffee and a choice of hotsoups. From then on everyonelooked at me with increasedrespect. There was magic inradio! Later this magic took theform of Barbara Shelley,GW7FFU, whose regular taskwas to travel with the WRVSvan. This meant continuouscommunications with definiteETAs, thus avoiding confusionover work schedules.

During my ‘tour of duty’ I spentsome time at most of thebeaches and was pleased torendezvous with GW0WBP atTenby Harbour, GW0RNK atLydstep Haven, GW7CDE atManorbier and other stalwartsin ‘semi-permanent’ locations.There was a short spell as arelief controller for GW3IGG onthe Ridgeway at Penally.

When GW4ZXL wascontrolling I was assigned tothe South PembrokeshireDistrict Council Depot at theSalterns, from where labour andequipment were deployed. Thiswas a demanding placement,requiring both tact and patience.Then, perhaps as a reward, Iwas asked to relieve GW7FFUon the WRVS ‘bun run’. Thisended at Freshwater East, fromwhere I returned toSaundersfoot with a specialpack of edible goodies forGW0RNK who was searchingfor the Beachmaster. He, too,had found a spot in the harbour

car park from where he couldcontact the controller, but using25 watts I think. I was on my wayhome when I last heard himcalling control from a field atMonkstone Point - I wonder ifhe’s still there?

In conclusion I’m sure that Iam expressing the sentimentsof all who participated with thecommunications organisationswhen I say I am pleased to havemade a small, but important,contribution in assisting theauthorities in their fight tominimise the effects of the SeaEmpress oil disaster. On apersonal level I feel that myknowledge and experience ofradio has benefited.

In the Midwest of the USA in late 1993, the Mississippi and Missouri Rivers burst theirbanks, causing devastating flooding. American Emergency Operations Co-ordinators(EOCs) provided the organisation behind what became one of the longest emergencyamateur radio rescue operations ever.

Amateur Radio has played a vital role in providing emergency communications

in times of need. The relief work in numerous disasters - both natural and

man-made - has been aided by amateur radio communications. Just a few

examples include the Mexican and Armenian earthquakes, the Lockerbie

aircraft disaster, the humanitarian crises in Rwanda, Burundi and

Zaire, and the others on this page. In this country, the devastating

North Sea flooding of 1953 led to the RSGB forming Raynet,

formal groupings of radio amateurs who provide

communications in times of emergency.

During the recent war in Bosnia-Hercegovina, the enclave of Bihac in theextreme north-west of the country was under siege for over two years. There wasno postal service and the town’s telephone exchange was destroyed by a shellwhich meany that only communication with the outside world was by amateurradio. In this picture, an elderly lady receives a message from her family via thestation of T91FNO. Queues built up outside the 'shack' as anxious members ofthe public waited to pass their messages to friends and family elsewhere inBosnia.

Only with regular training exercises can groups of amateurs be expected toprovide an efficient communications service during genuine crises. ExerciseRave, organised by the Llanfairfechan branch of the British Red Cross Society,assumed that fighting had broken out at a crowded rave party, leading to manycasualties. This training exercise allowed participants to practicecommunications skills, as well as first aid, ambulance and leadership skills, ina realistic environment. Here, Raynet member Wyn Evans, GW6PMC, helps RedCross volunteers put a ‘casualty’ into an ambulance during Exercise Rave.

Cyclone Val struck Western Samoa in the South Pacific with devastating forcein 1991. For five days, winds of up to 150MPH pounded the islands, destroyingthousands of homes, causing millions of dollars worth of damage, killing 14people and injuring many more. The whole country was cut off from the outsideworld and amateur radio provided the only communications into and out ofWestern Samoa. Amateurs in Australia and New Zealand contacted 5W1JL, achurch club station in Apia, the capital, and helped to organise immediate aidrelief from the Australian, New Zealand and Canadian governments.

PHO

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User ReviewRSGB

The new DJ-S41 reviewed.

ALINCO HAVE justbrought out a hand-held transceiver forthe 432MHz (70cm)

band which is not only extremelysmall but also relativelyinexpensive at just under £150.The cost and size have beenkept down by the use of ordinary‘AA’ type batteries and a poweroutput of only a few hundredmilliwatts. Despite thesecompromises, there are stillmany useful additional features.

The first thing you noticeabout the DJ-S41 is how tiny itis - it’s genuinely pocket-sized -and then its weight. This reallyis the sort of radio you wouldn’tmind carrying everywhere yougo. The next is the ingeniousfold-down antenna (the radioand antenna are shown actualsize).

It is possible to run the radiofrom ordinary dry batteries(preferably Duracell or equiva-lent), or from rechargeableswhich are available, with acharger, from high street shops.At 4.5V the output power is320milliwatts. A power-in socketis provided on the top panel fora 5.5V stabilised DC supply;this increases the output to420mW.

CONTROLSIN ADDITION TO the powerconnection, sockets areprovided for an external speakerand a microphone (or packetradio TNC). All three socketshave rubber protective covers.A chunky on/off and volumecontrol is also mounted on thetop panel.

The left hand side has threerubber-covered push buttons:PTT (which is in exactly theright pace), a Function key whichchanges the way the otherbuttons work (see below), andL/Monitor, which opens thesquelch (there isn’t anadjustable squelch control) andallows the controls to be locked.

On the front panel is the usualdisplay, a tiny window approx-imately 2 x 1.5cm which displaysno less than 12 things, includingfrequency, channel number,battery level, signal strength,power output, repeater shift andCTCSS tone.

Six small buttons make upthe rest of the controls. Theyare each a different size,presumably to make it easier todistinguish between them in thedark - handy for everyone but areal bonus for blind operators.The loudspeaker and micro-phone are located next to eachother and take up almost half ofthe front panel area.

FACILITIESUNFORTUNATELY, the onlyhandbook available at the timeof doing the review was inJapanese (the penalty for beingable to tell you about this rigbefore anyone else). A few noteswere available in English but itis possible that we have missedsome facilities due to the poordocumentation. ImportersWaters & Stanton tell us thatthey will be producing someproper instructions in English.

The radio will transmit on thewhole of the 70cm band from430 to 440MHz and tunes from415 to 470MHz on receive.Attempting to transmit out ofband produces the word ‘OFF’on the display.

Pressing the UP / DOWNbuttons alters the frequency in25kHz steps, or a quick press ofthe Function key allows tuningin steps of 1MHz or 100kHz.

Pressing UP or DOWN forabout one second starts thescanning facility. This scans thewhole band, or the memorychannels, and stops for aboutfive seconds before moving on.Scanning can be halted bypressing UP or DOWN.

A light can be switched onbehind the LCD display, thoughthis should be used sparinglywith dry batteries. The samebutton can be used to startAutomatic Power Off (APO)which switches the radio off afterthere has been no activity forseveral tens of minutes.

The DOWN button, whenused with the Function key,allows adjustment of the CTCSStone. According to theinstructions, pressing either UPor DOWN whilst transmittingsends a 1750Hz tone forrepeater operation; but we were

Alinco’s Tiny UHF Handie

The AlincoDJ-S41 is shownhere actual size.


User ReviewRSGB

unable to make this work. Thesame procedure with the UPbutton allows the frequencysteps to be altered: 5, 10, 12.5,15, 20 and 25kHz steps areavailable. Currently all UK 70cmamateur stations operate on25kHz spaced channels, though12.5kHz spacing may beintroduced at some time.

Twenty-one memory chan-nels (0 - 19 and Call) can storefrequency, repeater shift andCTCSS tone frequency. It isadvisable to set up all of yourmost-used repeater channelsin these memories to avoidhaving to remember to get thetransmit/receive split right everytime.

As with many modern radios,CTCSS is fitted as standard -this is used on many repeatersas an alternative to the 1750Hzaccess tone. The Call Memory

is a single channel, accessedby a call button; this is where tostore your local repeater or netchannel.

GREAT FORBEGINNERSCOMPARED WITH ITScompetitors, the DJ-S41 is smalland light. Together with theclever folding antenna, it makesthe most portable transceiverso far produced. The memoriesmake operating easy and theCTCSS is a bonus.

The receiver worked well inon-air tests. It proved to besensitive and produced loud,clear audio from the loud-speaker.

The transmit power is lessthan most other handhelds, butit is surprising how far 340mWwill go, especially if all you need

to do is reach the local repeater.Because of the unusualantenna, however, it isimpossible to connect the DJ-S41 to an external aerial. Thisreally would have been usefulin order to increase the effectiveradiated power (ERP).

Most of the controls are easyto use and are located close tothe appropriate finger. Onceinstructions are available inEnglish, this should be a verygood radio for the beginner. Itwill also appeal to anyone whowants a truly portable 70cmtransceiver, ready for use atany time.

The DJ-S41 is priced at £149and is available from Waters &Stanton, 22 Main Road,Hockley, Essex SS5 4QS; tel01702 206835, who are thankedfor the loan of the review model.

STOP PRESSAt the time of

going to press,Waters & Stanton

are in contactwith Japan

seeking a solutionto the 1750Hz

tone burstproblem.

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On The AirRSGB

THE LOG BOOKIN MAY, AS THIS is being written, radio

propagation conditions are improving

somewhat. On HF, the 14MHz band (20

metres) had been virtually ‘dead’ after about

1700UTC during the winter months. This is

to be expected during the evening close to

sunspot minimum. Now, with the lighter

evenings, the band is staying open later,

often until almost midnight. On the higher

frequency bands, the usual summer

Sporadic E ‘season’ has now started and

will continue until about September. Sporadic

E propagation brings strong signals from

European stations, particularly on the 28

and 50MHz bands (10 and 6 metres).

Hercegovina, YU1BN in Yugoslavia

(Serbia), 9A 3AT in Croatia, S57AC in

Slovenia and EU1AA in Belarus.

No fewer than 33 special event stations

were on the air on 12 May from windmills

and watermills around the country. The event

was to celebrate the 50th anniversary of the

Windmills and Watermills Section of the

Society for the Preservation of Ancient

Buildings. QSL cards featuring line drawings

and the history of each of the mills were sent

out to those making contact with the stations,

and an example of one of the cards is pictured

here. Also, stations making contact with 10 or

more mills could apply for a special certificate.

P A Williams, 2E0AJE, of Wakefield,

West Yorkshire, reported the following

stations on 50MHz: T97V in Bosnia-

2’s CompanyNews and Reports from Novice Licensees

WE START with asuccess story. It isoften said that theNovice licence

should be seen as a steppingstone to the full Class ‘A’ or ‘B’licence. One young man whohas certainly taken full ad-vantage of this is MatthewKennedy , formerly 2E1DRF.Matthew spent about six months

on 70 centimetrespacket radio andtook advantage oflast year's goodconditions to worksome DX (longdistance) byvoice. However,by the end of thesummer, he rea-lised that hisrange was limited.C a l c u l a t i o n sshowed that lessthan half a watt ofpower was reach-ing the antenna,due to the loss inthe feeder cable.To improve

things, more power was needed- in other words, a full licence!

Looking at a sample paper,Matthew realised that just onthe strength of his Noviceexperience - practical trainingand actual operating - he alreadyscored around 40% on the fullRAE. Matthew’s father is Dave,G3VZE, and he was able totrain Matthew further. He satthe exam last December.

Meanwhile, Dave taughtMatthew Morse with a series ofshort sessions, sendingcharacters at 12WPM but withlong spaces. With one sessiona day, all the letters were knownin two weeks. Speed wasincreased to an overall 10WPMand punctuation introduced. A‘barrier’ occurred but this wasovercome and after a totalpractice time of only about eighthours, Matthew took - andpassed - the 12WPM test.

By this time his RAE resultarrived - a pass and a credit -and Matthew applied for hisClass ‘A’ licence immediately.

He now has a brand-new ‘M’series callsign: M0AAT.

Congratulations to Matthewfor this success story. By theway, Matthew is still only 11years old.

SPOTSNOVICES ARE OFTEN‘spotted’ as DX stations on theDX PacketCluster. This is apacket radio network used byDXers (those interested incontacting stations in rarelocations or with unusualcallsigns) to share informationabout the activity of DX stations.

For example, P Knapton,2E0AJY, of Huddersfield, WestYorkshire, was ‘spotted’ on theDX Cluster when he wasoperating on CW (Morse) on3565kHz on 13 May. P AWilliams, 2E0AJE, ofWakefield, West Yorkshire, wasalso spotted, this time on 6metres. He was taking fulladvantage of the recent ex-cellent Sporadic E conditionson the 6m band.

11-year old Matthew Kennedy, M0AAT,who ‘upgraded’ from his Novice callsign2E1DRF in April.

QSL card from GB2MMW, which operated fromMarsh Mill at Thornton Cleveleys in Lancashireon 12 May.


On The AirRSGB

THE LOG BOOK

The Amateur Radio Spectrum: The 4 metre Band

Band by Band

Jasmine Marshall, G4KFP, organised the

‘national mills day’ on behalf of the Denby

Dale Amateur Radio Society, and she and

her husband Bill, G4IOD, were amongst

the operators at GB2GW at Gleaston

Water Mill in Cumbria. Jasmine comments

that she very much hopes that the event will

take place again next year.

British club stations will be able to use

special short callsigns in certain

international HF contests from this year.

The callsign will consist of G or M, a regional

locator (except England), a digit

corresponding to the year (6 for 1996) and

a single letter. Fifty-two callsigns are

available each year: G*6A - Z and M*6A - Z.

Look out for these special callsigns in the

FOUR metres, the70MHz band, is the‘odd man out’amongst the UK

amateur bands. Unlike almostall of the other bands, whichare allocated on a worldwidebasis, 4m is only available foruse by amateurs in the UnitedKingdom, Ireland, Gibraltar,and - by special permit -Cyprus.

In the UK, the band isavailable to full class A and Blicensees (not Novices) on aSecondary basis only. Thepower limit is restricted to22dBW (equivalent to 160watts). The band is availableon the basis of non-interferenceto other services, includingthose outside the UK.

During the summer months,typically May to September,Sporadic-E propagationoccurs on 4 metres. The mostnoticeable effect is thereception of Eastern Europeanbroadcast stations, which use

frequencies between 66 and74MHz as well as the 88 -108MHz band. The Polish Radiotransmitter at Gdansk on70.31MHz is a good indicator ofSporadic E conditions.Broadcast stations use wide-band FM (WBFM) rather thanthe narrow-band FM (NBFM)used by amateurs, so the signalswill sound distorted unless youhave a receiver capable ofresolving WBFM properly.

Much 4m amateur equipmentis converted from ‘low-band’VHF PMR (private mobile radio)commercial equipment,although AKD Ltd (tel: 01438351710) makes a 4m NBFMtransceiver which sells for lessthan £200.

4m is close enough infrequency to the VHF / FM BandII broadcast band at 88 -108MHz for a 4m Yagi to lookvery similar to a domestic VHFradio aerial, and therefore beunobtrusive on almost anychimney.

Look out for 4m activity during

the RSGB's VHF Field Daycontest on 6 / 7 July. There is aCW (Morse) session at 1400 -2200UTC on the Saturday, andan SSB session at 0600 -1400UTC on the Sunday.

major international contests, starting with

the IARU Championship on 13 / 14 July

and the RSGB’s own Islands on the Air

(IOTA) Contest on 27 / 28 July. Both

these contests are 24 hours in duration,

from 1200UTC on the Saturday, and both

are mixed mode - SSB, CW (Morse) or

both. In the CQ WPX CW Contest on 26/

27 May, which covered six bands from

1.8 to 28 MHz, propagation conditions

were generally considered poor.

However, the widespread sporadic E

conditions, referred to earlier, provided

participants with an unexpectedly high

number of 28MHz contacts.

Carsten-Thomas Dauer, DL2OBO, lives inHolzminden, Germany, and was first licensedin 1989 when he was 16 years old. He is a keenDXer and has operated from several countrieshimself, including Liechtenstein, Russia,Jamaica, Monaco and Lebanon.

BAND FACTSAllocation: 70.000 - 70.500MHz (Secondary)UK Band Plan: 70.000 - 70.030MHz .....................Beacons70.030 - 70.250MHz ................... SSB and CW (Morse) only70.250 - 72.300MHz .............................. All permitted modes70.300 - 70.500MHz ......................... Channelised operation

(12.5kHz channels)Activity:70.000MHz ................................... GB3BUX Buxton Beacon70.010MHz ................................ GB3REB Chatham Beacon70.020MHz ..................................GB3ANG Dundee Beacon70.025MHz ............................... GB3MCB St Austell Beacon70.114MHz ...................................... 5B4CY Cyprus Beacon70.185MHz .................................. Cross-band activity centre70.200MHz .............................. SSB / CW Calling frequency70.260MHz ................................. AM / FM Calling frequency70.300MHz .......................................................... RTTY / fax70.3125MHz ......................................................Packet radio70.3250MHz ......................................................Packet radio70.3375MHz ......................................................Packet radio70.4500MHz ....................................... FM Calling frequency70.4875MHz ......................................................Packet radio


Operating FeatureRSGB

Medium Wave Broadcast DXingby Ian Poole,G3YWX

THE MEDIUM waveband can be anexciting huntingground for listening

to distant stations. Althoughmost people think of the shortwave bands as the best forDXing, it is surprising what canbe heard on the medium waveband. There are signals from allover the country, and at nighttime many more from all overEurope can be heard. There iseven a chance of hearing theodd signal from the other side ofthe Atlantic.

EQUIPMENTONE OF THE advantages aboutmedium wave DXing is that nospecial equipment is needed tostart. An ordinary transistor radiocan be used. Many car radiosalso perform well.

If more money is available,the portable ‘world band’receivers like the one shown inthe photograph can be put tovery good use. A variety of thesesets are manufactured bycompanies including Sangean,Sony and Panasonic, and offergood performance withouthaving to pay the cost of a fullcommunications receiver.

These sets usually cover thelong, medium and short wavebands up to 30MHz as well ashaving a VHF / FM band. Theyalso give digital tuning and allowthe exact channels andfrequencies to be located.

Obviously if a communi-cations receiver is available thenits superior performance can beof great advantage, especiallywhen the conditions are difficult.

WHEN TO LISTENDURING THE DAY it is possibleto hear local radio stationsrunning low power at distancesup to 100 miles or so. Obviouslythis depends on the channelbeing clear of local stations.Higher power stations can beheard over greater distances.Some may even be audible overdistances of around 200 miles.

At night, stations from muchfurther afield can be heard.Distances of up to severalthousand miles are possible forhigh-power stations, althoughlow-power local stations maybe limited to distances of around500 miles. However, patienceis often rewarded and it may bepossible to hear even greaterdistances.

LISTENINGTHE MEDIUM WAVE band isorganised so that stations arespaced 9kHz apart in Europe,although for anyone fortunateenough to travel to the Statesthey will find the channel spacingthere is 10kHz.

Car radios with digital tuningautomatically skip one channelat a time, and do not tune inincrements of 1kHz. This makesseeking out stations mucheasier. Even without the setpicking the channels, one soongets to know the frequencies ofthe channels.

The main problem withmedium wave DXing is the sheernumber of stations which aretransmitting. Each channel maybe used several times within

The medium wave band runsfrom 531 to 1620kHz in Europe,with stations every 9kHz (notethat each channel frequency isdivisible by nine). In NorthAmerica the medium wave bandis 530 - 1600kHz, with stationsevery 10kHz. The best-heardNorth American stations in themedium wave band are CJYQin Newfoundland, Canada, on930kHz and WINS in New Yorkon 1010kHz. Reception of bothof these stations tends to bebetter in the winter than thesummer, and is only possibleat all late at night. Whenpropagation conditions are verygood, they can be picked up ontransistor portables or on carradios, but generally acommunications receiver willbe necessary.

The Sangean ATS-803A ‘world band’receiver is typical of those used by manyhobbyists to pick up distant stations onlong, medium and short waves.


Operating FeatureRSGB

* The World RadioTV Handbook isavailable fromRSGB Sales,

Lambda House,Cranborne Road,Potters Bar, HertsEN6 3JE at £17.39(RSGB members) /

£20.46 (non-members).

Europe. In fact with the numberof independent and BBC localradio stations, some frequen-cies are used several timeswithin the UK. Each stationwhich uses the channel will beoutside the normal range of anyother using the frequency andinterference should not occurduring the day. But all thischanges at night when moredistant stations can be heard.

To find a long distance stationtune carefully over the band.Some stations are easy to find.The Voice of Russia WorldService can be heard mostevenings on 1494kHz putting ina very strong signal with its oneMegawatt transmitter andsuperb antenna system justoutside St Petersburg. Itbroadcasts some interestingprogrammes, and is often heardin English in the evening.

Much closer to home is theBBC World Service transmitterbroadcasting from Orfordness

in Suffolk on 648kHz. Again thisuses a very high powertransmitter (500kW) and can beheard over most of the SouthEast of England during the day,and further afield at night.

For anyone taking up thehobby more seriously a copy ofthe World Radio TV Handbook*is very useful. This is publishedevery year and gives thefrequencies of broadcast

QSL card from WINS in New York, a broadcast station often heard in the UK on themedium wave.

stations in the long, mediumand short wave bands over thewhole of the world.

CONCLUSIONAN ENORMOUS variety ofstations can be heard. Thismakes medium wave DXing aninteresting addition to the hobbyof amateur radio. What’s moreis that it is usually not necessaryto invest in any new equipment.

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A Simple 50MHz Beamby RobertSnary, G4OBE

THE 50MHZor 6 metreband is onewhich can

offer a lot of interestingcontacts (see D-i-YRadio Vol 6: No 3). Thereare several very goodcommercial antennasavailable for this bandbut it is far moresatisfying to operate astation using one thatyou made yourself.

The antenna config-uration, shown in Fig 1,is essentially a two-element Yagi with thedriven element andreflector bent towardseach other to reduce thesize.

The antenna is knownas the VK2ABQ and itwas originally designedfor the high frequencybands (14, 21 and28MHz) because itprovided useful gainwhile occupying less space thanthe conventional quad or Yagiantennas.

The advantages of thisconstruction are:

It is physically small.

The construction is simple;by using a wooden frameand making the elements ofwire the antenna can be builtusing simple tools. It alsoallows the antenna to beused for portable operation,such as a scout camp,holiday or special eventstation.

CONSTRUCTIONTHE WOODEN CENTREpiece is used to hold the woodenelement supports and is shownin Fig 2. The centre piece isalso used to fix the antenna tothe mast. This can be achievedusing a strong shelf bracket,

one end fixed to this centre pieceand the other to the mast. Theelement supports (spreaders)can be made from canes orwooden doweling and fixed tothe centre piece using cableclips and adhesive.

If the antenna is to be used asa permanent installation thespreaders should be weather-proofed using a proprietarywood weatherproofing. The wireelements are made from plasticcovered wire and are fixed tothe spreaders using plasticinsulating tape.

The element end insulatorsare made from perspex or plasticas shown in Fig 3(a ). Theantenna is fed with 50 ohmcoaxial cable. An additionalinsulator, see Fig 3(b ), is usedto fix the coaxial cable to thedriven element. The coaxial

C RSGB DY310

C RSGB DY309

Fig 1: Plan view of the complete 50MHz VK2ABQ antenna.

Fig 2: Centre support piece.



C RSGB DY311

MATERIALSCentre Boss Hardwood 75mm x 75mm x 25mm (6in by 6in

by 1in)4 Spreaders 1.1 metre (3ft 8in) long wooden canes or

6mm dowelsWire 1.5mm diameter copper wire, about 13 metres50Ω coaxial cable RG58 or similar for short runs (up to 10

metres)6mm cable clips to fix spreaders to bossPoly-Urethane Varnish to waterproof the wooden structureSelf Amalgamating tape to waterproof all solder jointsInsulators see text

Both imperial (feet & inches) & metric (mm & cm) sizes have beenquoted for the wood as a lot of wood suppliers still work in imperial.

Fig 3: Details of insulators.

cable can be supported at thecentre with a cable clip.

An antenna element cut inthe centre so that it can beconnected to the feeder cable isknown as ‘balanced’. However,coaxial cable is an unbalancedfeeder. Normally, connectingthe coaxial cable directly to abalanced antenna does notcause any problems; however,in the unlikely event that youhave any interference problems,you could use an RF currentchoke to reduce the currentflowing on the outside of thecoaxial cable braid. Thecheapest and easiest way to dothis is simply to roll up some ofthe coaxial cable that feeds theantenna until you have 6-8 turnsof cable with a diameter of about20cm, supported by the coaxialcable support clip at the centreof the antenna.

ADJUSTMENTTHE DRIVEN ELEMENT is fixedto the end insulator in such away as to have two short wire‘tails’ about 10cm long, see Fig1. The antenna matching is doneusing an SWR meter and thelength of these ‘tails’ are trimmedfor minimum SWR in the sectionof the band where you want tooperate. Do not trim the elementend with the transmitter on, therecan be high RF voltages there,even at low power.

When transmitting tomeasure the SWR make surethat you do not cause inter-ference to any other stations.Listen on the frequency firstand use as little power aspossible.

PORTABLE USETHE ANTENNA CAN be madeas a portable version by usingthe cable clips as describedabove, but instead of gluing thedowel spreaders as well as fixingthem with the cable clips, makingthem so that they can slide inplace. Using a small drill bit,make a hole through thespreader and base plate so thata nut and bolt can be used to fixthe spreader firmly into place.

The prototype had an SWR of1.2: 1 at 50.2MHz. The first testswere done with the antenna 3mabove ground level. Strongsignals were heard from theGB3NHQ beacon at Potters Bar,

Herts (about 6 miles from mylocation). The GB3BUX beaconat Buxton, and some other weakbeacons were also heard.

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RSGB Letters and Diary

.

Keep sending your letters and photographs to:The Editor, D-i-Y Radio, RSGB, Lambda House, Cranborne Road, Potters Bar,Herts, EN6 3JE, and we will send a pen to the sender of each letter published.

JULY6 / 7 RSGB VHF Field Day Contest, 1400 - 1400UTC.

7 3rd 144MHz Backpackers Contest, 1100 - 1500UTC.

7 York Radio Rally. Details 01904 426421.

13 Cornish Radio Rally and Computer Fair. Details 01209 821073.

13 / 14 IARU HF Championship, 1200 - 1200UTC, CW / SSB.

14 2nd 50MHz Backpackers Contest, 1100 - 1500UTC.

14 RSGB Low Power Field Day Contest, 0900 - 1200UTC, 1300 - 1600UTC,80 & 40m CW.

14 Sussex Amateur Radio and Computer Fair. Details 01903 763978.

20 144MHz Low Power Contest, 1400 - 2200UTC.

20 RSGB HQ Car Boot Sale & Saturday Opening. Lambda House, CranborneRoad, Potters Bar, Herts. 10am to 4pm. Details 01707 659015.

21 Colchester Radio and Computer Rally. Details 01376 571239.

21 432MHz Low Power Contest, 0800 - 1400UTC.

21 Humber Bridge Radio & Computer Rally. Details 01482 837042.

21 McMichael Rally, near Slough, Berks. Details 01628 486554.

27 / 28 RSGB Islands on the Air HF Contest, 1200 - 12000UTC, SSB / CW.

28 10GHz Summer Cumulative Contest, 0900 - 2100UTC.

AUGUST4 RSGB National Mobile Rally, Woburn Park, Beds. Details 01277

225563.11 Derby Mobile Rally. Details 01332 556875.11 Flight Refuelling ARS Hamfest 96, Wimborne, Dorset. Details 01202

691021.17 RSGB HQ Car Boot Sale & Saturday Opening, Lambda House, Cranborne

Road, Potters Bar, Herts. 10am to 4pm. Details 01707 659015.18 432MHz Fixed Station Contest. 1700 - 2100UTC.18 Great Eastern Rally, Kings Lynn, Norfolk. Details 01553 765614.18 Red Rose Rally. Details 01204 62980.25 Galashiels & DARS Open Day and Rally. Details 01896 850245.25 Torbay ARS Rally. Details 01803 214445.26 Huntingdonshire ARS Annual Bank Holiday Monday Rally. Details 01480

431333.

A WARM WELCOMEI AM WRITING to congratulateyou on a very interesting maga-zine. It has helped to introduce meto the exciting world of amateurradio.

I have recently joined my localclub, the Reading and DistrictAmateur Radio Club, and took partin the recent RSGB HF NationalField Day contest, which was goodfun. I have had so muchencouragement and help from theclub, especially from Tom Cannon,G0VQR, and I am confident that Iwill pass the RAE in December.

Ben Firth

YOUNG AT HEARTTHANK YOU for such a lovelysurprise - my first prize in yourD-i-Y Radio competition for Jan -Feb 1996.

Actually, I shall be 70 years ofage on 20 July this year and havehad connections with radio since1926, and by 1936 I was well onthe path. I like D-i-Y Radio formany reasons, one of which is itkeeps me feeling young.

Ray Hounslow, 2E1CQL

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