RADIO A HOME - MADE ELECTRIC CLOCK. :'i& vol. 6 No. 10 JANUARY, Registered et the G.P.O., Sydney, for transmission by post as a periodical.

Transcription

1 . :'i& YaOlYal/lleF2172. RADIO vol. 6 No. 10 JANUARY, 1945 Registered et the G.P.O., Sydney, for transmission by post as a periodical. > A HOME - MADE ELECTRIC CLOCK

2 PAGE II. RADIO AND HOBBIES IN AUSTRALIA JANUARY, 1445 aeressid 6reer inzâcâ To -days demand for Qualified Wireless Operators and Broadcast Technicians far exceeds the supply. MARCONI SCHOOL GRADUATES HOLD THE BEST POSITIONS IN AUSTRALIAN RADIO They... are employed in Radio Development and Research Laboratories... Staff A.W.A. Beam Wireless Stations... Operate all A.W.A. Coastal Radio, Island Radio and Broadcast Stations.... Are in charge of Aeradio and Ship Stations.... Maintain Ambulance, Police and other mobile Radio Services. MARCONI SCHOOL OF WIRELESS CONDUCTED BY AMALGAMATED WIRELESS (A/SIA) LTD. 47 YORK ST., SYDNEY QUEEN ST., MELBOURNE Tel. B 0522 Tel.: M ;,.!', n1 At" Vai ^ BROADCASTING COASTAL RADIO -

3 f&c1ronic 2uiure ELECTRONIC devices are finding ever-increasing application in modern indust'ry-counting, controlling and sorting ith a degree of precision unsurpassed by the skilful operative. There is little doubt that electronics will figure large in the postwar world and that this "by-product" of radio will be established as a virtually independent industry. Reviewing overseas technical literature, one realises the versatility of the art and the impression is apt to be gained that electronics can accomplish just about anything. On these grounds there has been much speculation about the impact of electronics in everyday life. Radio, we are told, will cook your meals and dry your hair. Radio will open your doors and turn nn the lights at dusk. It will help park your car and apply the brakes when a collision is imminent. Generally speaking, these and similar suggestions are within the realm Of present possibilities. Your gate and your garage door could he made to open in respqnse to your headlights or horn, or al a radio signal transmitted from the auto radio set. There would be no need to get out into the pouring rain. All very nice, hut the construction and installation of such gadgets on a commercial basis would run up into a tidy sum. A few would be sold but most would be content to put up with the inconvenience. Su too, electronic heating and drying methods have been available for certain specialised tasks, cutting the time factor and material wastage to a mere fraction of what it was by earlier methods. But electronic heat is heat in a very expensive form and its application is wasteful if the job can be done as effectively with conventional methods. The question with electronic devices is not so much "is it possible?" Rather, is it worthwhile from a practical and economic viewpoint? It is dubious logic which argues that a device or method must be employed just because it happens to he feasible or "modern." 1f the electronic industry is to develop on a solid footing. its products must be sold on their proven merits. Undue stress on the novelty aspect can only react unfavorably ;it a later date..-- INDEX --- [ I Page Page Electrons Aim The Tank's Big Gun.. 3 Radio Valve Design And Application 28 Puzzled?-This Is How It Works... 5 Comments On The Phase Splitter.. 31 Soil Erosion-A National Tragedy.. 5 Soldering Pencil From An Old Cell 32 Australian Broadcasting Stations... 8 Broadcast Band DX These Planes Are Making History 9 Short-wave Notes Two Long Range Allied FlyingBoats 10 This Month's Recordings. 39 News From A World At War 13 Build Your Own Synchronous Clock 15 Working Model Of An Anti-tank Gun 40 Sound On Film (Part II) 20 Hints For The Home Handyman Effective Homemade Rotary Switch 25 Joe's Column Technical Book Review.. 27, 42 Answers To. Correspondents 43 McGILL' S Radio Column Price Post Amplifier Manual-Dirent Couples FM-AM-A. C. Shaney.... S/ Australian Official Radio Servire Manual, Vol Reccty- 16/-.. 4d Australian Official Radio Service Manual. Vol. 8, 1989 Receivers I6/-.. 4d Radlolron Designers' Handbook. 5/ R.C.A. Receiving Tube Manual. 2/9.. Sd R.C.A. Transmuting Tube Manual 2/9.. Sd All About Frequency Modulation -Radio Craft Library /-.. Sd Modern Battery Radio Sets - Radio Craft Library... 4/-.. Sd Modern Radio Servicing Technique-Radio Craft Library.. 4/-.. Si How To Make Good Recordings- Audio Devices /8.. 4d Frequency Modulation - John F. Rider /-.. 4d Servicing By Signal Tracing - Cathode Ray Tobe At Work - Meter At Work-John F. Rider.. 16/- Servicing Superheterodynes - John F. Rider /-.. Od Radio Handbook-Jones.... le/-.. 4d Audel's Radioman's Guide /-.. lid Ghlrardl-Radio Physics Course. 48/-.. 8d Ghlrardl-Modern Radio Servie - Admiralty Handbook of Wireless Telegraphy. Vol. I.... 5/3.. 8d Admiralty handbook of Wireless Telegraphy, Vol, S / Amateur Radio Handbook-English Radio Handbook SuPPlemenl - Companion to the Amateur Radio Handbook., /8.. Si The Radio Amateurs Handbook- A.R.R.L., 1044 &ilion / A.R.R.L. Antenna Book.... 4/8.. Si An Elementary WI - Course for Beginners /9.. 4l Practical Radio Communication- Nilson & Hornung - (Snd GERNSBACK'S EDUCATIONAL LIBRARY Ilid each, pont Yd. Radio Fur Beginners. How To Have Fun With Radia. Beginners' Radio Dictionary..4,W au Lbe*U p1.4,0 Alternating Current For Beginners. How To Build 4 Doerle Short Wave Sets. How To Make the Most Popular All Way; t & 2 Tube Receivers. Simple Electrical Experiments Television. MCGIILL'S AGENCY for all your Technical Book requirements ELIZABETH STREET, MELBOURNE, C.1. (The G.P.O. Is opposite.) (Cent ) PUBLISHED BY ASSOCIATED NEWSPAPERS LTD., at ELIZABETH -STREET, SYDNEY. Phone B0333. Box GPO, Sydney.

4 ADVERTISEMENT ANN A MAJOR ügne2a TECHNICAL IMPROVEMENT "PERMIICZAD" mew Kingsley announce "Permaclad" I.F. Units, Coils, etc., rep ting one of the most important contributions to Radio Comp Manufacture in "X014 years. Complete stocks are now being made available from our Authorised Distributors throughout Australia. 4e. FEATURES * "Perrnaelad" Components show "Q" values approx. 33% greater than the conventional type of Units. This means less loss. * The restriction of the magnetic field by the "Permaciad" principles permits a smaller shield to be used withoui affecting the inductance or "Q" values. * "Perrnaclad" Units are smaller than the conventional type units. * "Permaclad" Units are specially designed for "replacement" work. KINGSLEY RADIO 225 Trafalgar Stre.t. Petersham. N.O.W. 380 St. Kilda Rood, Melb, Vie. It will he of intereil to runny of those in the hdlo West, 14 Rehr that hfr. Loy the and that eeeeee los joined Cingiley cos i Inglner of Purls Melon Ruccessful conclusion under his PTY. LTD. Telephone: LM 1166 Telephone: MX 1159 was brought to guidocw MAE TWO RADIO AND HOBBIES FOR JANUARY, 1945

5 FEATURE STORY ELECIRONN AIM THE TANK'S BIG GUN Electronics has solved one of the most baffling problems connected with tank warfare-that of keeping the heavy gun trained on a target while 'the vehicle speeds over uneven ground: A small but efficient device has had a far-reaching effect on long accepted tactics. he had already figured out during his work with industrial electronic devices. Most promising of all appeared to be his "micarta spacer" and 'silverstat," a combination of spring leaves and resistors, which could direct a substantial electric current through a controlling device in exact proportion to the direction and degree of external pressure exerted on It rhe tank gunner's problem is not a difficult one to visualise. Next time you are in a moving car, pick up a slick and see how difficult it is to aim at any small target. Even on a good road the car bumps and sways sufficiently to thwart your best efforts. You will find the point of the stick describing crazy zig -zags all round the target seldom straight on it. But take out all the springs, block out 90 per cent, of the view, substitute a hefty cannon for your stick and drive over the roughest road you can imagine. Well, the tank gunner's problem is something like that. It's even worse than a naval gunner's job, whose steed is bigger and does 'buck" with some- semblance of rhythm, Realising the position, military corn - CORRECTLY AIMED SHELL HITS ENEMY TANK Hanna's ideas about the silverstat proved correct, for it was readily adapted to the job. But the stickiest problem was to convert the controlling electric impulses into mechanical force sufficient to manipulate a massive steel barrel In a quick and positive fashion. There could be no room for uncertain or sluggish action. In this the physical law of inertia rendered Hanna considerable assistance. SAME TANK IN THREE CONSECUTIVE POSITIONS ^ ;.; ü 4.1i.r.)i SECOND SHOT MISSES; GUN AND TANK POINT DOWN menders had long adopted "leap frog" tactics for a large-scale tank advance. One half of the tank force would advance, while the other half stayed behind to maintain an offensive and covering lire. Then the forward tanks would grind to a stop and open up, while the others advanced in their turn. Big drawback of such tactics was that the speed of advance and firepower was automatically cut in half, while the stationary tanks were naturally a sitting shot for watchful enemy gunners. Little wonder that tacticians have longed for tanks which could maintain accurate fire as they plunged forward over the obstacles and shell craters' between opposing lines. ACCOMPLISHED FACT By the middle of 1941 the tactician's dream had become a reality. Allied tanks sped over the battlefields of the bucked and pitched as of old, but the snout of the big gun drew an unswerving bead on the target. Secret lay in a small, black, thousand - dollar box fitted above the breech of the big gun. Product of nearly 18 months intensive search, it was compact enough and adaptable for the -largest and the smallest tanks alike. The story of the mysterious black box had its immediate beginning early in 1940, when an engineer of the Pittsburgh Westinghouse Laboratories-Clinton R. Hanna-tackled the,job of stabilising the big gun in a pitching tank. Half of Hanna's 44 years had already been spent in a world of electrons, and the job, to him, did not by any means appear an impossible one. Hanna believed that the key to the solution would be found among the dozens of gadgets _ GaJ. rl - - THIRD SHOT OVER- SHOOTS TARGET; GUN AND TANK POINT UP _ : r,'/ The big steel barrel m itself shows a definite disinclination to whip about with the movements of the tank, but with rigid ' mounting it has no other choice. Hanna found that, when suitably mounted, less pressure was required to maintain the gun at a given elevation with respect to the horizon than might at first be thought necessary. The bigger guns, with their greater inertia, are actually the most co-operative of all, and a controlling pressure of only 200 -odd pounds is sufficient to provide the necessary encouragement to "stay put" on the target. The first complete apparatus was tried out with success in the laboratory on a dummy gun made from all nvn Oar. 1veX1. seep was to fit it up under battle conditions for a trial at the Aberdeen (US) Proving Grounds. Ordnance officers who t' Essential details of the gyro -stabiliser unit for tank guns. Up and down tilting of the gun causes the gyroscope to "pre - cost" horizontally, disturbing the balance of a n electrical circuit which controls the oil - hydraulic system. saw the test were elated. Here was a device which would outmode at one stroke the tactics forced upon the German' panzers by the same problem. A device which would step up considerably the hitting power of Allied tank forces. As might be expected, heart of the gun stabiliser is a built-in gyroscope, run at no less 'than 14,000 rpm by a small electric motor. Spindle of the gyroscope is roughly In line with the gun barrel, But it is pivoted along a vertical axis and so arranged that tilting of the gun barrel causes the gyroscope to rotate slightly or "precess" on its vertical mount. A projection from the side of the gyroscope fits between the contact leaves of the silverstat, which produces a balanced or unbalanced current through its two halves, according to the pressure exerted on It by the controlling gyroscope, As the leaves to either side are com- pressed, so an increasing number of resleance segments on that side are shorted. out, reducing the total resistance and allowing the current through that portion of the circuit to increase. Current flowing through the silverstat from an external source affects two solenoids controlling a pair of balanced jet valves in a hydraulic system. when the gun is at the required elevation, the valves are open equally; forces tending to elevate or depress the Sun exactly balance. But let the tank tip forward and immediately the elevating valve is opened wider and the pump slams extra oil into the top of the hydraulic cylinder. Down comes the breech and up goes the snout-that is, in relation to the (Continued on Next Page) GUNNER CANNOT CORRECT GUN'S ELEVATION FAST ENOUGH FOR THREE SHOTS TO HIT THE ENEMY TANK WHEN TIPPING OF TANK CAUSES GYRO TO "PRECESS" AROUND VERTICAL AXIS, BELLOWS CUSHIONS ITS MOVEMENTS SPRING HINGE PIVOT tlbcikic MOTOR\ /` ;GYRO'S (HORIZONTAL a.axis PIVOT dicarta ;PACER RESKTORS G III GYRO'S VERTICAL AXIS SHAFT TO ELEVATION HANDWHEEL GEAR BOX OUNTED ON Gl1N BREECH CRADLE SILVERSTAT CONTACT LEAVES GYRO CONTROL UNIT GYRO WHEEL (14,000 R.P.M.) RADIO AND HOBBIES FOR JANUARY, 1945 PAGE THREE

6 C FEATURE STORY tank chassis, in reality, the gun has simply remained at the desired elevation with respect to the target. In actual fact, the etabntser b pyyto layed ta set Iheeueld Initial a elevation hell. -ell. Brain of the stabiliser the Gyro Con - hol Unit ( I, a black boa mounted on Ihn breach at the gun. ln mechanism is shown ai X 0 o ape lmn +24eb.'t+{_ ~n incorreci'aim IF 61 WERE 'WON P NQr grmlus HTDIIAIMIC MERE THE SPACERC CYLINDER /HAS CUT OUT MOST ANR iltilng INTO OF A ELEYAT{ON DEPRESSION RE318TOk n detail on th. proeiow Thee When tilting of the tank change. the althation of the un barrel from the line in he the m GaAs lsillversfat Tiro a.uur mo r a currant tornontallyoflow through nether he elevation or th. de ICI OI (haver et of r(d) is directed b by magnetically s (hi the, top Lotto. of cylinder (F) under beachpdeped lher the [needed correct,. u upverd or d S. Th...Iteg moon 9 eh th. piton in the eylloder ra or lovers Ike breech. Even the org, eat e,m,g of the gun la done through Ma gyro control unit, as seen under Confront.g Mambo. (Drawing by courtesy of Popular Science Monthly O I CONTACTS oat Uh a :ainfofn. CAB + A Olt Fite{ MAGNEir_ CONTROLLING ELEVATION tíev íí íp cúú ry cosy mew va.ncu lhemaller It upetatea tom m et Teats ahow that cetera lute t *en le nt therror tertpm I[th ehlne at hum a ot l. h hue to rot the tide -to -side movement. 1 but that is the vastest part of tank Üte velure of hie htoyentlon gunnery. waslnut dol, closed at the t Standing in the turret of a speedmg Meanwhile tank, It u was It being is Impossible for an observer flit to d to all detect any American up-and-down tanks-large andsmall-and movement of the n alt But ted In the gunthe details passed over to British and ner's guhal t, the Russian authorities, An b entire refrigeretch and down Ina ator plant of the most aiarming Westinghouse Commehton. pany, its was turn - over to the math BREECH nufacture of the device. IS STEADY The Germans found out about Actually the breech Is relatively Hanna's wok the hurd way, tit took steady, you ere bobbing up and dawn them some -I h 1 L f the tank. It's ysea stime to discover thets s. BHyenas vet gas not unlike sitting their at the intention o extpeme end ut i copying railway carnage, looking at the ear Hut Hanna Is confident that the immediately in front. It appear to be matter will not rest In the Implement. doing all the rocking. of tear. Already he has ideas of apply - American Ordnance thought so much mg It to railroads and c to provide the smoothest ride you s have ever of the little black box that Hanna was known MOON AFFECTS RADIO RECEPTION That radio reception has been found to vary with the phases of the m as disclosed recently in a General Electric Science Forum address by Dr. H. TStetson of Combridge, Mass., of the laboratory for cosmic re arch, Mass. Inst. of Technology. I'l'ING the results obtained from radio way over the path we wets data after more a than 20,1111[1 hours retying," Stetson' pointed out. o[ observation over Iwo periods uc "The s er thin happened M both lour }'ears each, I1r'. Stetson said: sertes of data, except that the lunar effect was more p, dining the "From the study of out data, made ud toot years of our data,hors duron those Manta when the moon was ing the first four year:;, overhead, we found radio reception de- "We know there is increasing evifinitely improved from the nip f the dence,n believe that out In space moon, first quarter to shortlyter before sun use pe emitting very penetrating full moon. full moon radio re- energy. ronebl5' similar ception dete,orated but began rayx-nt Mgr h rto prove again from about the last quartet t "It is these rays which bombard the until a few days before new moon. Thu, (per atmos he+e of [hr of course, is true for a certain particular earth a en Eto the Joas anâ electroru in our so-called frequency over a certain path we were ionosphere. 'Unlike the earth, the moon has no. in ohservatlons made when here to stop or absorb these rays, "the moon was below the benison,' we Every six-rays, found no such effect, where no radiation ra s, worker knows that when 0e Very from the moony =lace mold reach the violet rays, shines on a meal Platte-ca almost any substance, for that matter -- the object so Illuminated sends off This is what we call the plectrons. hotoelectric effect. "It is what happens in every photocell that counts the automobiles upttos th t paini along thtl operates the self - opening iirshfoundri so many publie In r hypothesis, we believe that emitted from the moon, the e intensive sunlight. In ce s e unprotected b that It ka these photo -electrons coming t from the moon and entering thé earth's atmosphere that have the Tc c :r.e ease the tonlsatlon of out radio ailing. 'In fact, radio observations show that the intensity of ultra-violet light hitting the top of our atmosphere is more than twice as great during sunspot maximum than during sunspot minimum. We should therefore, have a right to expect that the photo -electrons emitted from the moon would be appreciably increased with the increase in the intensity of the solar accompanying large heri et sunspots.. PAGE FOUR RADIO AND HOBBIES FOR JANUARY, 114S

7 sat. 1 POPULAR SCIENCE A fascinating cycle of operations goes on the working of the gas -operated refrigera tor, which is without moving ports and uses a flame to freeze! The main sketch shows the principal parts of the refrigerator unit in very simplified form. As In the raze or the elerfrlcally-driven COMPreas. of le 00 Iht Tarpe t 1hsebest is'abépbed when lhe a body` changes its stale frmn liquid to vapor. In to case of the gas tor kerosene, refrigerator. the cycle is complicated somewhat be twwe it 4 maintained without moving parts. The unit alternately vaporises and liquefies a using the s onto o and o agar. When the ammonia vapor Is liquefied, heat Is r given off; this purr of the process therefore takes place aide the 1 chamber. n the am la aborbed from uedln areas; part of the maces la earned on the refrigerator chamber. I SEALED GAS CIRCUIT The refrigerating series a ylndrsrlde together he1osgelier- 10 0c single m r unlcating container. Within the closed cull is sealed a and ammonia), with a little of the gas hydrogen to equalise the pressure throughont the and and tofacilitate the small quantity of aqua-anunonla,distilled water freezing process The pressure Is suffielent to madman ammonia vapor at ordinary ases Mom m temperature. The process can be followed from The diagram. Starting at the lower left hind corner of the diag em,,thee beat flame to theomlear frof small amvapor to be driven offer together w th a small quantity of water valet'. The gases pass through the raper coder to the water separator, where baffles condense the wale_ vapor into aamt which drops back to the ballte. The dry a oni6 gas passes to the lower portion of the condenser where It le liquefied by cooling. The Mould ammonia next passes into the ice -making compartment of the unit. If all the anunonia vapor' not condensed In the Deer portion of the condenser, the' reswae rises co the u0pet part where [ Is condensed. tt then Rows down to join the other Irgnid. liows down HYDROGEN ATMOSPHERE As the ammonia t1vough the u tube the ice -making' o pertinent.or "low-temoerature radfaeor"1, it absorbs heat and evapor-. ates, thereby producing refrigeration. Al this point hydrogen gas Is mixed with the ammonia vapor In the eveporere nhr o rthei ll oev solution. at the bottom of the abeoeber w ammonia vapor at causing con[inued and -from here le drawn.trues by contefrigeration. duction to a tots of piping at the bue The gases are next led down to the of the boiler The Strong solution forse absorber. Here the ammonia fr Is reabsorbed bythe same liquid frontwhich It driven out lo boiling,liquid having run ore to the absorber from the boiler. hydrogen gas remains and rises again to go erns the evaporator, hydrogen being insoluble le'in water. The liquid having absorbed the ammonia, cumulates ae a...on. WA1EIfVAPIGFtLIIIIFy1NG, DPDpS FALLI G ygwlaa ACK TO BOILERmra-_+ its way to Elfe sop of the boiler, completing the cycle of the ammonia. The rate at which the cycle operate. governs the aunt of refrigeration. Hv eutomatle control, te cycle Is re ceased at the correct rate to maintain the pre-determhued temperature In the cool chamber. fii111ìlïíïilìll1r IIIIIIIIIIIIIIIIII yaympmqdgenfta R6fi--H 11(IBI... IIIIIIIIUea.... ;IIIIIÌ111/ HEATING PANEL Heat of 90 deg. F. is developed in penel-celled the Yarvorth heating panel this di inventor-of o p end wire laminated with phenol-fcrmald.- bed. resin. The wires serve a double reinforcing eh. lamination and being a ged to develop resistance w hen plugged info en ordinary electc,let Is en English a"lieli Th. Farrel now being used o n shipboard and en theflowsof a mobiles, buses and ae Temperature It so In. that thloat thh ere ne o danger of burning 0 o can.. content with the :ni low r wall. P.nels f h.b.ek d fe..boulation when used on Peon..ktrvetine ihi. p.nel, the r I.ee.. into eh feinicss. term lore,ie wyh ends eyleted to goad f aa1 c If isthen lam tee with and sr make a Rant,sartle thee, 1/14ín. Ih sk weigh.,sg about o fool. Ti,. herd glassye surfer.i asquare reported to b. of, and nonconducs 'sve-"foolpeoof send ind..f.uefible." the Moll The.era B:rfi Min 1ahy of H.eleh bet red use f the panel as "rondo,' end short-m.1.r A new Curtis fighter monoplane de lgna[ed the Curtis 21P-62 has flown in the Hen. Thus type may be the Curtiae ivalent of the new Bell P-63 single eingla meter lighten RADIO AND HOBBIES FOR JANUARY, 1945 PAGE NYE

8 FEATURE STORY Then grain a have the m eet ne method,. m the tillage of thfarming e soli AO the land becomes mole hillsides Trees erems are on felled and the land Is thus deprlied of their binding roots The farmer ploughs his field ue and down the slope and perhaps over the top n these torrone the ware runs eaads ow instead of soaking Win and carries th it the tupbeen oil that has AI sixty mile been ploughed houre danstom The soil Is Breduswats needs alli washed into i smell sounle tows the stream that bcrtler sa has pro_ hip A fee seconds pelts t the bo late. h place tom he ll and midnight dark imer the hlstream nsn becomes silted up the farmer Is then deprived of he. to Once again drought has the country in its grip; east oreos at soli M his wate supply s well. precious land are being wach devastated by scorching winds, which farm adds Its quota to this pro - eon of so that blow away the vital tap soil. Holdings ore rendered useless; the country becomes i in s few year, easy Meg to cattle are dying in th ds and ruin laces many Farmers. droved conitions such are in evidence. TO Il,e city dweller. safe in his led to unwise mellmds of tilling the so These are the simple feett and 11 part - suburban villa. Ills tragedy being of attempting to make exile pent by reasons for the extinction of at emel acted in miry. semis to,, far keeping down costa. Or by trying t pires of bygone years. What can be a awa to ltu a, r rlleal5e farmer without the neceesair c at- equipment parelively tranquil existence, either nl machinery CPórirslorh or there Isarlea evldencepen. knowledge. slow thatwe any more rai nod by But let him tek, a warning that. this Vast of land besot ly Nature than were the empires of Babymatter Is a vital to hiscontlnned com- coded, lleva been der to clear lon or Medo-Persia. fort and welfare as Is that of keeping ostures In order to clear n Archaeologists tell us that agriculthe foreign invader from our shores. for the landscape has bee de ture had its origin In the plains of For that matter, fro frequent r, ti - don of the present conditions o tided eesf [ and scrub. the Mesopotamia and the Valley of the Id tars being d for lumberhe a shat p Nile, and, because of the greet fertility ender our country fit for no one but 'pay" for the v enturv The result e there plains, the rate of Produetinr the Japs temoon Whic su lteble greahrga pvof was s high. This high rate of preduc- That is the stark truth; truth which party, which cwille or sheep real bled labor to be diverted into it Is useless b deny for we have thou - lowed b rem at will. the er art and s and these coo ends of years of helory to prove it. niesernes became the 'die of our Mvlllu- Soil erosion Is note new phenomenon, tion. neither are the measures of preiention, examination ofrewrrle will show. IRRIGATION SYSTEM Food is the basis of our lives. With- The allmial out it. civilization cannot t advance and, land of Mesopotamia in the last analyse, an our require - dy Calelk formed washed down fwas m., physical and eulturel, are purfrom the mountain. y of I Armenia by the chased with two rivers, Tigris food. wduringt the seasons and Euwas phrates. s thew In primitive times practically all land we re engaged In the production of food It Zi%Qlt I',ó irrigated by a system canals from war not until twowere the man found the of hers m muddy, and of producing this, together with natnrel a surplus that labor could erosion deposited large be diverted to other channels, there to quantities of silt be employed In the various sib the canals. n ls, so that It becamenecesd There comes a time, however, whe sary lo be clearing them crafts which Ills Innate continually. genius <levied. cattle or sheep are pasture d This task, however, was a formidable no L mall a property, with the r FOOD VITAL and n nals had eventually to ult that shrubs and grass and es bee dug, soethat by repetition there But food was the vital re meet, he roots deare destroyed. With tile veloped a VaS4 system of silted canals, whatever other occupations n e prac- gone there Is nothing left to bind th hlell ever captive Jewish slaves tised, Timber cannot be felled without soli. Babylonians could feeding the woodmen; coal could not be Rain comes and a stream nf brought in clear. dug without feeding the m chil- water, flowing down oval cuts a Mai dren could t be taught without feed- In the too s ll. Later rot When the clearing work as inter- 'n g duele rupted by foreign invasion or other ing the teachers; soldiers must be fed enlarge this envy drain trash become disorders. the water supply was allot before they can fight. Yes, the bask ugly scar ten to thirty off feet aid from the farms and cities and the of existence is food. Let the city dwel- as many deep and with a length o[ Empire ler remember this when he finds a ten- nrhaps half a mile or more; the Nks became to u der (far too often, I am afraid) to let the face of the once perfect field. T omad tothea from thenumerable m In - pne Wise the other man do the worrying. sides fell In and n tons of top sort or These tribes, time and again driven What ten has happened to ' our washed away as the seasons pass by ger, Came a own into the ains 'high" order of society If the reme- Then drought eppearsóielur red in it where thefame grew sufficient plfood dies for soli erosion are known, yet not work by the lack of moisture presery to knee the people living In comparasppuedy The answer lies In man's in- ing foliage; the grass dies off, leavin g tive comfort. Here they sacked the sane Idea of teeing to make everyone the too oil exposed. Howling villages and burned the titles and inner and d hang the consequences. n rarer this s top solll avow into the atmaa passed on The race for personal wealth and Ib leaving ran ndernrae These cumulative interruptions in concomitant, personal competition, hats where once was as paradise the work of irrigation belly reduced PAGE SIX. RADIO AND HOBBIES FOR JANUARY, ives

9 .. Ilea FEATURE STORY RICH LANDS ARE BECOMING A DESERT the peopl to the state when they were sable t resgt the inroads of the desert tribes, and the eúrpire became extinct. Eleven moires rose ana fell In Mesothe t12th and happeas Lortgflis aepoohat much an the w uae of Zed Y 'r anything else. Grim stories can be told of 0 civilization in Egypt and Africa He. ere. eat doily deserts cover the oe rm great title. of ;he Romans and Phoenician. 100 DEAD CITIES Pr. In Northern Syria, between Hama Aleppo and Antioch. an area et a. little over one million am' of limestone a untrywhere about 6100 dead NEW SOUTH WALES titles stand in stark ruin in soilless land. These r' not In New South Wales d. dam et Cuna burled langhanr Creek, near Harden, was built ]Eke 50 many in lowlands, boot stand n 1912 with a 421n, wall. By 1929 iffs rip sere like ghosts in bare reign storage was completely flned with limestone country. Far the sail hat cubic yards of silt. Rivers like been washed off from three feet to six the Hunter, which had flowed persistfeet as red from floor sills to bare ently through notable dry spells, ceased 'ock.! In a these lands Is written a re-.. cord of land wastage that knows 11 0 v. o flow during the less severe 1940 parallel. The a can never be Not only have farms gradually int peopled, for the re basis otheir 0 0V food geeing Ooedwelerr.weer the lop mil Moir vital top soli, but they are losing production is gone-the soil 15 good from high ground Is hell -bury (hit crop also the s of then water supply. (LISA Department of Agriculture of young car, DiFeranr melted of A truly v vicious circle! report.) eullivelinn might lave saved both The Generally speaking, et 101 is used Could anything more horrible be imagined, War knows no such devastation. Imestigatlan of s ail and the crop. by five different factor001 Sheet er - 'here the top sod is 'Skelatlo" this area showed that be the land w originally stated that, before Use coming of land; (2l bwse f v getstion, white men, America had 820,000,000 teres which dad the land of rgrcoiog of ultivnitdnteìiswsecatioeudedh nil of its vugln rarest. Today there fl e only is a d grasses; (3) f 150 binding materials with mflion a es fil one Infor lumbers In Lhe pa land ceasing de005l of 10,1- great dust ' storm of May 11, 1034, It 000 binding routs and grasses; (bo evitable result. estimated that the wind swept twat' Mat tear out the sides of the hills; and Ill Egypt, soil erosion of the hill- 350,000, of topsoil from the wheat (6 into act tjo f,aping ground. sides was unknown o any large scale When liana 'Coded, the trees, n Beto Incthe Ira of the Phoenicians. There plac Were o Tiers hold this sell addition [o supplying the fore then, the. farms were located in n placd "Putts of Inc e Basket b0ntling by their roots, provides eespro the allcvial beds. of the.valleys. The the and 00 ma 0000;eihr f Phoenicians, however, came from the became the must Bowl. Bolld Wheat farm - foliage' takes the shock sand desert and settled on the mountain became desertslay and valuable meat- allows the water to drop gently on to slopes, as also did the Israellles. ("B lay iam, away the ground. In addition, the ground on These peoples tilled the soll of the ("Buildinge America.", Me vicinity of the trees is lopes and cleared the land of its essen- The same thing.s ha and water soaks gradually ma through porous, to tial vegetation. The land became ex- in our own backyard. Right feed throughout perhaps rtesian wells, or r toto posed to the blasts of wind and the Me country, in every the mil treaml'alod of et dash of ram, and, in time, the red being carried away, earth was washed Into the valleys, re- ford topsoilrcan or aiabys tosdel the violently leer Élu aril entl filling the Even rivers with gilt by ducing the productivity of the land and 1233n. ICOuUuned au Fare 10) undermining the food supply of the It has been estipeople. mated that It N takes Nature CONSERVATION METHODS bout 400 year. a id It was n these p arts that 1asingle inch first ap- of tjbai, the peared remedial methods of land. and title e va [ion; the very samemethods that be eeme.ed are should e in use oday m all fo lice. Lebanon and Palestine have been found rack -walled terraces built on the hillsides. Behind the walls which ^ were from two to six feet high, soli was deposited. This formed a level surface Ilke which crops were VFetar 0 rli e r o nturies andonwhic water garden were originlay forfor a greater period than formerly. ally nine T was laid o no roes of earl. n har e1 9ndernrground. Id the se!0000 mart', Arabs. the A tingle wind storm landwall w n by the Arabs. The lifted enough roil To walla fell Into disrepair and much of Inc sell waswashed Into fie sea. The devastating Amts ea roll n very marked in America, where the p has become o trhe serious. Toion give some of the relationship r It of areal Edna and sou erosion, it can idea. them e. elyh u e ad. 2 1 to the c'urrodt'.beef of wind drought. ^t y y yeer rte m two or three years by the Ordinary recesses o [ a few f eras I figures, selected at anàom Illustrate the nature of the widen' In Australia. particularly with aspect to the silting of rivers and ds In Gippsland, 1800 acres bordering the Avon River have been destroyed, every worth from 20 to 50. The r rvoir has' been reduced in capacity from 14,000 to 0000 acre feet. That on the Elidon aloe,. was decreased by 1600 acre feet in the first ten years of r s life. At Bruthen, the first bridge over the Tambo River hea been completely burled under a gilt deposit. RADIO AND HOBBIES FOR JANUARY, 1145 PAGE SEVEN

10 I DX NOTES ALL AUSTRALIAN BROADCASTING STATIONS Complied By Our DX C pondent, BOY HALLETT Call. Kc/s Met. Power. Location. 2CR A 10kw. Commack OWA A 10kw. Minding 3WV A 10kw. Horsham SOL A 2kw. HOb6rr A 10kw. Sydney 2PC PREFIX lette," fo cell signs have Ihe following tignifcence 2 -Ne.. South Wales; i.: 4-0ueensl.nd; 5 - South uslrelie; e -Western Australie: 7 -Tasmanie; 9 -New Guinea. Th is in Cumn00k, NSW. ENA 1. el Mind - no. W.siers Assirelie. The t~n in conne. - fion witheach arl.mtionad laiontrier. in mot ce+. lo the he 02. I.eq orally relay the n val 0.8g arum. or on, *afin, in Ihec tel city. B clou Rlehoe pe ste in relay far agent, pr.o.g..ra.mma.. POINTS OP NOTE The ir.q.ency for each dation n be Iole* as.ci value. Fgure.n4 ',ove - length are approximate only. decimal quantifies being ornined. Th. power in- dicated ic that ec,ally in me by the culer station. w The pro% letter "A" bel... th. on..r refingindicai., lhel Ike sl.8ee s National or Gov.rnmenl ne n.d.lalíen. cp.nbd by the Au.bdi.nlreadeealing Connehden. "I" indle.l.. Ihat Ibo.telle* i pirate', e.01. an.ner Mite,. d ecial The following e.11 dura.. e longer loer hard having boss the a a r fer.rai y.. 2%N Lismor.; KY Invertit; 3H5 Hor.hemi 3146 Burcdp changed call end location fo 3CV Cherlleni 707 UIenfone changed cell and loe.lion t 700 Derenporl; 907 Sunbury is nos. o8 the air a, also is 290 NewcaalI. end 6111 ninth. 81./ion 1UW Sydney i. Aceielie'. only 24.hour station. but 3A1 Melbourne.enema on the au ell n;ghy. Noie Ihe1 I Iilow.N in.quel Ro 1000 we Ha. K/ M t P Location. C 11 2O1, ]kw. Sydney DB Melbemne w kw. Crystal Brk. SPI CA 2kw. Canberra SSB kw. Kingnroy 3AR A 10kw. Melbourne kw. KatamUng 4QN A 7kw. Tow.rwille 2RO w. Gr CK A 7.5kw. Crystal Brk. 711T w. Hobart 2DU B 200w. DubbO 2LT w HU H 2O0w. Burni! w. Rockhampton 'CO A 7.5kw. Co'owa 3LI lkw. Lubeck 2HR w. Iachinyar MD w. Mn 4AT A 500w. Atherton 7LP w. Duni/5110n 7QT H 300w. Qneenet9wu 4LG ewp A 3.5kw. Perth 21W w. Longreaeh w. Sydney 419C lkw. Brisbane 2NR A 7.5kw. Greffon 3CS w. Colack 7NT A 7.5kw. lxuneekmn 6PM w. Fremantle 6GP A 2kw. Kel1ympppBe 2AD 5CL 2HL w. Arousal. 411 A Skw. Adelalde ' 2W kw. Wage A 10kw. Sydney 7ZR w. Hobart 2NZ kw. InverNl 4QS A 10kw. Dolby 3LO A 10kw. MelbOmpe 3KZ w. Melbourne 2KA H ]kw. Katuemba 2CH lkw. Sydney 4TO B To93nsnD1! 53A w. Adelaide OWN A SUOw. Perth 2GF w. Grafton Poprler end.#tienf loom of lrensmil 3Y w. War of 2BH H 200w. Broken Hill 6KG w. Kalgoor000lielIt 490 Ring entier is e single,feel lo A 3 5kw. Brisbane,,el 4AK kw. Oakey B Rernnark.irh a erfh o eiew 2NA A 10kw. Newcastle I. bete. Hen io ib. v"711h kw. Newcastle _ 3OI A 7kw. Hale me.l of the National 495. D.Ib, lkw. Sale 20V A 10kw. Canberra 01X w. Perm 9PA w. Port Moresby B 500w. Hobart COIL 115/* Met. Power en kw. Shepparten 40R H 500w. Taownemba 4QR H 2kw. 8rlabane 20M ]kw. Sydney 2GO H lkw. Sydney 21.1E H lkw. Sydney OPR B Perth MIN B 500w. Adel Ide SAW w. Melb0urne 4WSC H 100w. Warwick H 500w. Bendi10 48K 30L B 300w. Warrwgal 4AY B 500w. Ayr 3TM w. Brisbane kw. Tarneet h 6AA B 5AD kw. 229 NOrthBD 500w. Atlelal0. SAN A 500w. Atlelald! :BA w. Ballerai 2LM H 500w. Lismore 2KM B 300w. Kenrpsey BKV H 500w. Perth 7AD B 300w. Devonport 2GZ H 2kw. Orange H 500w. Hun2aberp A 2kw. Puckham3ml3 4MB B 200w. M90b44mlgh H 200w. Swart 220, Hill H 200w. Cooma 7EX H 500w. Iaunceet0n 0Te H lkw. Derdónup 4VL H 200w. Charleville 4CA H 300w. Cairns 2LP H 300w. Young 3UZ B 641w. Melbourne H 750w GL x0 Geelong 4OY MA w. Gympie w. Milduya 4PM Port Moresby 2MO w. Gurmedah 5OE w. Mt. Gambier GE w. Gereldton 4BH lkw. Brisbane 70N 4MK w. GOWburn w. Mackay 2P H Parkes.5Aí H 2O0w. PL. Augusta 2M H 500w. Newcastle 3X H 600w. Melbourne B 500w. Wollongong 1440 H DenillgulO 2QN H 300w. pswich MG H 200w. Derby H Mudge B 300w. Cesmock 5MD B 200w. Murray Br. 2MW H 200w. M'lumbah H 500w. Maryborougll 2AY B 200w. Albury 28E H 100w. Baga B 200w. Rome B 100w. 0, AK H 200w. Melbourne. '146k E161-1 RADIO AND HOBBIES FOR JANUARY, I8

11 AVIATION THESE PLANES ARE MAKING HISTORY: France eall3 OE'ER ibis year. two Mosquito pilule-une an Australian. 1 It e other Canadian-- 'look it in (urne' ta destroy a Nazi 1lyingtrain ctimposett of a Ilya-englned Heinkel wiring two Gotha 242 gliders (skelrhed 'a1 lop). 'the Heinkel wee compositew of r 0 Eing - enchant nt Heinkel III's, their wings joined and a firm engine Bleed a the join. The fuselages were jointed at the tail by a wide tall plane and elevator. Heinkel III, the balls of this monstrosity has long been a main may of German Air Force. idifferent of Oie craft very in detail, but basnally it is a low -wing monoplane carrying asixndm tman ag flvo `g sle edle Recent events have indicated that the Luftwaffe has begu to concentrate on the defence of the homeland at the expense of the German armies fighting for existence on the various fronts. But, some i e ogo, when Germon expansion won at its eenith, the nand for big cargo- orders resulted in the appearance of some curious makeshift aircraft. is u straightas fer âs Me ergepevdeeles, tinned tips. The freight trailing dg rve m w meet e the auselage. There are gun positions [op f the fuselage end beneath. mingle fln and rudder and strutted tull- feet and Ls 111 feet o The long. Gotha The later I 242 gilder fide planes stubby}' toga bus... make up a the tail un otabilleeng floats are artially fetrao tl which lead backrtím wide tail ll Most e dlstinetive feature of the ALE - Defensive armament is reported otble. be "capable of facing l every direc- This bersame Or train quickly 223 design, however, Is the gear-[en tendue an " 212 e Prey [o [he Mosquitoes. heats maned directly in The general design Is ingreminiscent [ the base of the forward section of the the fuselage St eta LARGEST LAND PLANE shoulder -wing monoplane ion The six -angina Blohm and Voss HV - with we being tall single a s fln. The Messerschmltt ME -323 fcentra 222 tying -boat flower rlghtl is another Engines are 1000 horsepower radials, lelti is claimed by a Nazis to be the but or conventional giant. and the reputed biggest land plane in i the world. The prototypeprotoversitype crashed In1040 but a maximum sp pee 922 d if about 190 miles m ean It is powered by six Gnome -Rhone second in toe as Mum 9950 feet. engine, but is perhaps mom properly freight and regarded personnel trace - With their conquest', almost as a pmilitary ort In the Mediterranean theatre In y i verf pppad Dr mares, ee ngspite of the s pengin s, itowered cannot c leave 942. have little 1w h flying - the ground under engine power alone. The BV -222 ham a wingspan of ISO boat. When It la ready to take off, it requires the assistance of a tow plane and eight takemli rackets mounted under the Cananlidated Vallee are reporled to wings. PLANE NEWS:- be Wingspan.orking o super bomber, 8,32, of the ME -323 fe I81 feet. and length Is 93 feet. A CCORDING to eh. "Perko, Zeitung." comparable to the e B-99 Superlartraee. Ta It le claimed that thls huge craft the Harker Typhoon het top speed nab way for thia and ou rent.ark an ctransport fully te1901 édarmed soldiers, al 113 mph when Riled etch lour 20mee the production al the Liberator has cannon and carrying t.o bombs been Naiad doer. series of athe eaaelafe n pe, g or eight mate. Ill p ctile.. From the open to load heavy artillery United Slate, comes pr other e,e Ihre bulky military equipment. According to n American report, fop ',prising report of atp.rimenta eiek smell seche tion fuselage ep1d of the Fairer 1rrcuda is 254 mph!chin aeroplanes teling all and lending Is big to theuietly al 12,000 leer. an the decks of tank landing.hips LST'd. decre eeleses towards the tan. The wings,,which are Ceterpillar freaks are being tested in Apprenely lb. experiments have proved ylaced bib on the fuselryge, a ach 1.15 as landing goer for P-40 lighters. successful. braced with a single sr. e A huge RADIO AND HOBBIES FOR JANUARY, 1945 PAGE NINE

12 AVIATION TWO LOG RAGE,' ALLIED FLYING BOATS THE CATALINA AND THE MARTIN MARINER There are something like half a dozen versions of the Catalina, but there is no mistaking the general lines. Most distinctive feature is the large strut -braced parasol wing, carrying the two radial motors. During five long years of wor, comparatively little publicity hos been given the "flying ducks" of the Allied Air Forces-the Sunderlands, the Cotolinos, Mariners and Coronados, which have maintained ceaseless vigil over the sea lanes. Their job is not spectacular, but it is nevertheless a vital one in its contribution to the safety of shipping. THEY have no impressive top speed or powers of manoeuvrability, but there is something of majesty about their unhurried and graceful flight. There is venom, too, when they speed' down with Cannon and bombs to blast a lurking U-boat. This month we consider the smaller members of the quartet-the Consolidated Catalina and the Martin Mariner. The Catalina was first produced late in 1935 by the Consolidated Aircraft Corporation at their Buffalo plant, New York. It was the last of Consolidated aircraft to be built there, as moving operations to a new plant at San Diego, California, were proceeding. TFe YDR9_1 ne tl.e ntntnl one 'erne known, was a rather revoluti' iary design at the time, being the first flying - boat to incorporate retractable floats. integral fuel tanks, double -row radial engines, constant speed propellers, and full cantilever tail section,, The Catalina made Its debut for the United States Navy with an international record -smashing flight on October 14 and 15, 1935, from Cristobal Harbor, Canal Zone, to Sari' Francisco, California, a non-stop distance of 3281 miles, Large numbers cf the PBY-1 were ordered by the United States Navy. PBY-1 being the production model of the XP3Y-1 with slight revision of the rudder and minor internal modifications. This original version, of which some 60 were delivered In has a wingspan of 100 feet and a length of 65 feet 1 inch. Many of these "ships are :41i1 in service after eight years' hard work in all weathers and varying climatic conditions. The PBY-1 weighs 27,400 pounds fully loaded, and is powered by two Pratt and Whitney twin -row Wasps R-1830 engines, which develop1050 horsepower each. The top speed is 200 mph, and the ship cruises a total range of 4000 miles fully loaded at 130 mph. It Is this tremendous range which makes the Catalina such a valuable asset to the Allied cause. Models PBY-2 and PBY-3 are essentially the same aeroplane as the PBY-1 with minor modifications, In the PBY9 version, the design was enlarged slightly, the wingspan being increased to 104ft.,. t the weight to 30,000lb, and the length to 68ít. Larger Pratt and Whitney engines of a similar type but with an increase of horsepower to 1200 were fitted. and this gave an increase in overall height of 8in. Another and later version, the PBY-5, featured the installation of fully -enclosed waist gun positions mounting two 5 Browning guns in each blister. Incidentally, the "Cat" also carries by way of defensive armament one.303 hand - operated gun in the nose turret and one.303 gun in the floor immediately aft of the step. This makes a total of six machine-guns in all. A special amphibian. version was perfected in 1938 and is known by type number PBY-5a. In addition to the large numbers of Catalines delivered to the United States Navy, Consolidated Aircraft Corporation has also fulfilled quantity contracts to Australia, England and the Netherlands. OTHER FACTORIES Besides being produced at the company's factory in San Diego, the "Cats" are also being built in Canada by the Boeing Aircraft Company, and in Philadelphia by the Naval Aircraft Factory, where they are known as PBN-l's. This latter version has been modified somewhat, in that It is fitted with a sharp bow, extended rear step, and a higher and more rectangular vertical stabiliser and rudder. A useful addition to the Catalina is the fitting of reversible pitch propellers. which help greatly when maneouvring the big ships in restricted waterways. Basically, the Catalina is a parasol wing twin-engined flying -boat somewhat unconventional in the manner of wing mounting and hull design. The large wing, which carries the power plant, is mounted rather high above the water by means of a faired superstructure or pylon, as it is sometimes called. Height above water Is a very necessary consideration in the placement of the power plant In a flying -boat, so as to minimise troubles due to spray. By utilising the pylon method of mounting. the wing and power plant, it was possible to produce a very stable aircraft and also to keep the hull cross sectional Nicely "on the step." This Martin Mariner flying -boat is in service with the RAAF, carrying freight, mails and priority passengers between Eastern Australian capitals and New Guinea. Note the dihedral tail -plane and the fixed wing floats. PAGE TEN RADIO AND HOBBIES FOR JANUARY, 1945

13 machnecessary and.cause area down to ell 1 9Tó le highly desirable 1n the inter - erns o1 reduced drag. As e. further support to the wings, they are braced from the hull per medium of two struts on either side. The wing, which i very large, is metal nstructlon with fabric -covered control surfaces, and the tip portion is let down t act as floats when the ship Is et rest or lust commencing to taxi. An Intereeü feature of the wing le that it is By J. Finneran not sinmodern aldwra- a craft, but this fa hardly a slow-land -landing t plane. Stabiliser and elevatma are of metal cowstruction, 2abrtc-coshed and fitted with all - metal trim tabs. The vertical fin is of all - metal c d covering, while n t e rudder a metal framework with fabric coveri ng. Elevatora and stainlate mounted high onthevertal r fin so as not to be blanketed by the wing and pylon, and also it helps then, clear M spray. 'ARMAMENT The Catalina Yes Of s its range and The long time it spends in the adequate formeal prepay and rest for the crew has been Provided; also facilinee We ill for survivors of emy action, which it often picks up in i. chit mutiny. By way of ofienalve armament, Catalina. carry either two torpedoes or about 10001ó. al bombs or depth el arges. These are gall 'led externally der the winof k tblank M an t eh n yant a haves and been laid low by Nis ponnderou duck of the II It hadn't been for Catalina, the hiver n well have done much e damageythan it did. n Although hie. Catalina has done yeoeao. over the A ne elit and especial n, i[ may well thy that its htheing ground Is the.7pedal Vence the islands spread their Influence In the unds a the PwInde has been faded the he; ergs óhexh Y hie vecats, ngre themang acte a lanket doomsh and to the Alliedf [Tees theshrforrnatlón which has made possible such shattering a talks on the Japanese navy and the ferding outposts et Nippon. Erleny. the performance figures and dimensions of the Catalina are as follows: Wingspan bee feet, length 65ít. ills_ height left. 0mB gauss wing tea ]4011 sq, (F, aspect r Lio slob wergbt empty' hurt ó., loaded 3o.5001ó. Maximum fuel clvm ay 145d rmph sli=m. a range ti a mea a00 at In1L t, rage 000 Ires at 1e merl ereticlimb 1100[t. per Mute ana service refiner 25,200fí. A plane, which is dissimilar In SP - penne, butthco ImIlrerbltivtiespeIs perform le the Martin Mariner. The Mar - jeer lotlg-gauge petrol fling -boat fellows on what more conventional lines than the Catalina, but nevertheless features some unusual design aspects. The Mariner has been developed along novel lines In that a half -scale modal, the Glenn Martin Ill, was built and Mon first. This ship, the let was the AVIATION prototype in miniature and on it waa done all the developmental work ria eery to the s essl'ul culmination o Lhe Mariner inlid u prevent form. In this manner. it was possible ta have.something really better than wind tun- e) tests and yet keep development coats down to tee =sable figure. The recule _( ifs experiment w uch that the Mariner virtually fiepas sent[. oft the drawing board t e present guise. Bo s aesfulrw the metro; ploed [hat Ghe M liner in nias 72: e the prototype in m ui turn for tie Giant Mattis Patte lathe Martini Mars. Tris lande plane has a wingspan =f 2001í., a loaded wet t. 190,f1001ó.. and ts p=weretl with four hp Wright Duplex arineee lone The Mariner elibe Le larger eels Lc general of sng Me better perxm'mallin generally than the Catalina, except in he mailer M extreme unes. (paptmeed ea Nett Page) RADIO AND HOBBIES FOR JANUARY, 1945 PAGE ELEVEN f

14 A V I A T I.O N The fuselage of this ship is quite conventional in design and construction, being of the twin -step hull design and metal construction with stressed skin covering. The wing Is of all -metal construction with fabric -covered control surfaces and features gull -wing effect : and landing flaps. The use of the gulled centre section serves to keep the motors and propellers high above the water and out of the, spray, The plan form of the wing shows taper on Donn reacting and trainng edges and the wing is of full cantilever construction, obviating the necessity for any.external bracing. Retractable wing - tip flpats were at first fitted, but later dispensed with in favor of the fixed type, as it was apparent under Service conditioits that their added weight offset the advantages gained in other directions, The empennage is notable for its departure from standard practice and adds.an unusual degree of individuality to an otherwise usual flying- boat. The tailplane section, comprising the stabiliser and elevators, has quite a large amount of dihedral angle, and the ver- tical surfaces, comprising the titis and rudders, are attached at right angles. to these surfaces, thus giving a pronounced Inward tilt to them. The actual construction details follow standard practice for these assemblies. Power plant comprises two 1600 hp Wright double -row Cyclone GR ASB 14 -cylinder radial engines enclosed in rather spacious and lengthy nacelles. Three -bladed Hamilton Standard propellers are fitted. This ship carries a crew of seven in its roomy fuselage, and combines a satisfactory top speed with excellent seaworthiness. The RAF's Mariner I, is identical with the PBM3 of the US Navy, and the Mariner II. is the counterpart. of the PBM4. Both types are in use with the RAF Coastal Command. ana pernaps you may have been lucky enough to see them over Sydney. Defensive armament aboard the Mariner consists of two.300 machineguns in nose, dorsal, and tail turrets. making a total of six mg's in all. The offensive armament comprises some 35001b weight, and may be made up of bombs, depth charges or two torpedoes. Whea torpedoes are carried. they are the 22in. variety, and are stowed in the unusually large motor nacelles. The Martin Mariner is the product of the Glenn L. Martin Company, Middle River, Baltimore. Nebraska. The company's chief designers are Glenn L. Martin and William, K. Eb91. General dimensions of the plane are as follows: Wingspan 11Bft.. length 77ft 21n., height 17ft, 6in., weight loaded 48,00011:. Performance: Maximum speed 210 mph at 13,000ft.. with a range miles when cruising at 150 mph. Soil Erosion I (Continued from Page 7) Overgrazing of pastures has. already been mentioned, 'I ors is a serious cause of erosion In this country, as is also incorrect farming of sloping ground. The old square Iarmtng is long out of date in thie respect, where the plough is run up and aown the slope, forming millions of tiny rills, which water uses as channels. Terrace farming, mentioned as being used in Lebancn and Paiesotne In ancient times, is similar to the Contour Farming of today. In Contour farming, use is made of the natural contour of the land. Farming is done on the level, instead of up and down hill. by means of Contour Banks. These banks are really a form of terrace, running along the length of the slope. In appearance, they can be likened to an enuarged version of a piece of corrugated iron. The purpose of the banks is to reduce the rate of flow of water running downhill. The analogy of the corrugated iron can be pressed further. If you pour water on to the end of the Iron, you have probably noticed that It has gathered great speed by the time It is half -way down the corrugations. This is similar to the action of water running down the furrows that run up and down hill. Now pour water.across the corrugations and note the effect. The water runs more slowly, as It also does across the contour banks of the falm. Each row or furrow along the contour helps to hold the water where it falls, and it therefore soaks into the soil, instead of running away. There are various types of contour banks and, by arranging the alternate planting of crops so that alternate banks are either fallowing or growing rotation crops, there is a reduction of erosion risk that will repay tenfold any discom- fort the farmer suffers by having to change to the contour system. Our inland rivers are drying up by siltation from surrounding farms and grazing land; our very existence is threatened as much by soil erosion as by foreign invasion, in fact, more so. The days of destroying our country for the sake of the last penny profit by those who can shift to other climes when the occasion demands, must end, or we perish. For those who are destroying our country through lack of knowledge of the proper methods, education and assistance must be given so that the wonderful resources of this great country of ours will become the heritage of the millions in future years. If we fail in this. we deserve notning Reuter man cunucuination from our children, who will be the ones to suffer by our neglect. BQEI_NG "FLAK CRUISER" ;&CORDING to a German report, a Boeing B-40 is in service which carries no bombs but is armed with no less than 28 machine-guns and two 20mm. cannon. There are said to be six machine-guns in the nose, six in two dorsal turrets, eight in two ventral positions and four in the tail turret. There are three machine-guns and two cannon in each waist position. drugs are being used to save SLFAU the lives of thousands of farm animals, the American Veterinary Convention reports. Sulfathalidine and sulfaguanadine have produced very good results in the treatment of swine enteritis. PAGE TWELVE RADIO AND HOBBIES FOR JANUARY, 1945

15 TRAFFIC ALARM TONY ROSELLE, 10, 01 Atlanta, has invented a pedestrian clock which shows what time is left to cross a street before the traffic light changes. The invention, which has amazed engineers, will be used on millions of American street crossings after the war. Tony has his own workshop, electric lathe and drill. He keeps the electrical gear of his parents' home In order and repairs the family car. GRAVING DOCK THE Garden Island graving dock has been flooded for testing and drained. The clock will be among the 12 largest in the world, capable of accommodating any ship afloat. The Queen Mary (80,000 tons), when docked, would have 100 feet in length to spare. It is 1100ft. long, 150ft. wide, and 40ft. deep "at low water over the sill," meaning that ships drawing up to 40ft. of water can enter the deck at low tide. When full, the dock holds 50,000,000 gallons of water. Workshops will be equipped with modern machinery for carrying out repairs. An extension of the present Cowper - street wharf will provide a fitting -out wharf, I000ft. long. Construction work on the dock was begun early In * * DEADLY MOSQUITO MOSQUITO bombers of the RAF are now fitted with a six -pounder gun, besides four machine-guns. The gun is slung beneath the fuselage. and tires as the plane dives to attack. FEATURE STORY NEWS FROM AIVOR[D.AT POSTWAR AIRLINER THE Boeing Aircraft Company has displayed models of a new luxury transport plane -a double -decked strato -cruiser, based on the Super - fortress, but 12 feet longer. Company officials said that the plane could operate as a transport, carrying 100 passengers, with au operating cost of one cent per passenger mile, as a luxury sleeper plane with 72 day seats or 36 berths, or as a cargo plane, with a payload cf lb. The plane's range would be 3500 miles and its cruising speed 340 miles per hour. A pressurised cabin would give comfortable atmospheric conditions regardless of altitude. * * * NEW ANTISEPTICS? THOUSANDS of micro-organisms may produce even better antiseptics than penicillin, Professor Sir Alexander Fleming, co -discoverer of penicillin, said In his Lister memorial lecture at, Edinburgh University. Penicillin was not perfect, he said. For one thing, it was so rapidly destroyed in the stomach that it was Impossible to give it by the mouth. There was still scope for the chemist to synthesise it and then to tinker with the molecule so that Imperfections could be remedied. Pure penicillin, even if diluted to one in 50 million, would inhibit the growth of the common microbe of bolls and carbuncles, he added. On the other hand, it was so non-poisonous that so tar as he knew no one had yet had enough to poison a man..zicket TO MOON ROCKET flights to the moon costing as much as one day of war are predicted by Professor J. B. 8. Haldane. Writing In the "Daily Worker." Professor Haldane says If the human race so desires, giant rockets can serve other ends than destruction. He estimated that "moon rockets" would be practicable In order to photograph the other side of the moon's face. He points out that the German V2 rockets aimed at Britain rise to 70 miles when fired on an oblique course. A rocket fired vertically, therefore, could rise to 200 miles or more, he claims. Professor Haldane adds: "At this height it would be above almost all air, and if it released a camera attached to a parachute, it could take photographs in short -waved ultra-violet light which Is stopped "ThJs wouldbyair. give new information about the sun and other heavenly bodies." * * * PHOTO THROUGH STEEL DR. ERNEST E. CHARLTON, of General Electric Company's research laboratory staff, announced at the national electronics conference the perfection of a two -million volt mobile X-ray machine, capable of taking pictures through one -foot of steel. The machine doubles the available voltage for examining metal sections to find defects. The 50001b. apparatus is able to radiograph eight -inch steel castings in three and a half minutes, or 77 times as fast as a one -million volt unit. I R.A.F.'S NEW BOMB SIGHT ( OR the last two years Bomber Command has been using a bomb -sight of whimf some details may now be given, the Mark XIV, or the T.1 in the US Air Forces, The sight which was in use in 1939 was effective only when the pilot was flying straight and level, but the Mark XIV is accurate even though the bomber has to take evasive action. The first ones were delivered to the new Pathfinders force in August. 1942, and before long the Mark XIV was in use throughout Bomber Command. Used for attacks on small single targets, such as bridges, the Mark XIV consists of two main parts-the sighting head, which Is in the nose of the Cralc, auu a +CU6a+1gUla1 UVA cu++cu a ccmputor, The necessary calculations, taking Into account the speed and direction of the wind, the airspeed and ground speed and the height of the aircraft above the ground, are worked out in this robot. All the bombardier has to do is to give the box the five facts, three of which can be set In the machine before the aircraft takes off. 1; t y FLAME-THROWER BERLIN radio claims that a new German weapon Is operating on the Western Front-a radio -controlled flame-thrower battery with a jet of 200 yards long. NEW FIBRE DETAIIS of a new British fibre, claimed to be the strongest in the world, were given recently in a bulletin released by the Associated Chambers of Commerce of Australia. The fibre is being used to make parachute canopies and cords for dropping supplies from planes. The fibre, called Fortisan, is a product of British Celanese, Ltd. RADIO AND HOBBIES FOR JANUARY, 1945 A group of mechanic; are shown servicing an RAAF Kittyhawk, back from offensive patrol. In the foreground is a wrecked and abandoned Jap fighter-"oscar" to the Australians in the area. PAGE THIRTEEN

16 ADVERTISEMENT BRIEF SELECTION FROM OUR EXTENSIVE RANGE IS SET OUT BELOW dal 249 _ ne ni.o-cefngn...a mr'c. Ip. va.,. Aame anlw ANGUS & ROBERTSON LTD., 89 Castlereagh Street, Sydney PAGE FOURTEEN RADIO AND HOMES FOR JANUARY. INIR

17 gauge BUILD Yrilli STATOR ASSEMBLY The stator requires two soft iron or mild steel plates 3 inches in diameter and approximately 1116in. thick. These are marked carefully for 15 holes, as in figure tit, and drilled with a No. 37 drill which has been oilstoned slightly small on the clearance edges. This makes a hole which is a snug fit for 12 -gauge nails. It is necessary now to remove the shaded portion of one plate only, and this also requires care. Drill a series of holes in a circle closely adjoining each other, removing the centre in the manner in which I have no doubt most of us have cut valve socket holes. The raw edges are removed with a half -round file to the edges of the 15 holes. This leaves a ihin, diameter hole surrounded by 15 smaller holes, into each of which 9!161n. long portions of 12 -gauge nails may be inserted and soldered. In the centre of the remaining plate, Fi,9 ore 4 Figures 3 and 4. Pivot brackets for the rotor, which require to be screwed or soldered centrally to the stator side plates. Pivots may be from an old balance wheel assembly. CONSTRUCTION I OWN SYNCHRONOUS CLOCK By A. SPRINGETT (VK 20M) With due consideration for the mechanical ability of "Radio and Hobbies" readers, and without making extravagant claims for its simplicity, this clock is within the constructive copaçity of most enthusiasts. IT requires patience, a certain amount of hard work and ingenuity; but, when finished, it provides a keen sense of satisfaction in the accomplishment. The degree of mechanical skill required is probably a little higher than that needed for the pendulum clock described in the July, 1944, number of R & H but.' as I said previously, by no means beyond the reach of mechanically - minded readers, A synchronous clock depends for its accuracy upon the frequency of the alternating current mains. FREQUENCY CONTROLLED This frequency Is controlled at the source of supply over definite periods of time whereby gains in the total number of cycles In that period are controlled to a loss in the next, or vice versa. The synchronous motor which drives this clock Is not self starting, but needs to be spun up to synchronóus speed with a flick of the spindle. This speed Is then maintained constant by the alternations of the current, and the moment synchronous speed is lost the motor stops. It is obvious, therefore that, while the clock motor runs, it runs at a constant speed within the limits imposed by the variations in cycles of the alternating current. The clock, as a result, is an accurate timekeeper, -varying only a few seconds plus or minus as the alternations vary. Naturally, the motor is the heart of this clock, and numerous ways of connecting it to a clock movement will suggest themselves. However, let us first construct the motor. It comprises two main parts, the rotor and stator; let us tackle the latter first. A front view of the clock budt up by the author, housed in a small veneered clock case. Wheel train is from a German alarm clock and motor hand made From scrap metal. Figure I. Dimensions of the metal side plates of the stator or field assembly. One has a Kin, centre hole, the other a 17ín. hole, just clear of the ring of nails. a xl n. diameter hole is drilled and 15 2í 16in, long pieces of 12 -gauge nail soldered into each of the -small holes. Now take a piece of fibre or Cardboard Lobe 1 11/16in. inside diameter and press it over the nails on one plate, then mess the other plate in on the opposite side with one set of nails midway in the spaces of the other. This piece of tube should be lin, lung, thus preserving a clearance between the free end of each ring of nails and the opposite plate. Care must be taken that the sides do not slip apart, with possible disastrous results to the winding at a later period. The writer suggests that they be cemented securely into place with some suitable adhesive. Insulate the sides with thick paper, taking care that it adheres closely to the sides, as any projections catch the fine wire used for the stator winding. Figure 2. One of Rhe stator side plates. with the 12 - nails soldered in position. Tho second side plate has e Before proceeding further, it is necessary to make up a pair of brackets to carry the pivots for the rotor, One is a large U-shaped piece, the other a small rectangle, as illustrated in figures 3 and 4. Provision hits to be made for affixing these centrally with respect to the holes in the stator plates. The writer attached them with machine screws fitting slotted holes, but soldering can be employed by those who have no taps available. The actual pivots on which the rotor will rotate can well be the kalance pivots cut from the frame of an old clock movement. When the mechanical work on the rotor parts has been completed -ready for final assembly. one can tacklè what is pcssibly the most tedious job cf the whole project-that of winding the field coil. (Continued on Next Page) RADIO AND HOBBIES FOR JANUARY, 1945 PAGE FIFTEEN

18 CONSTRUCTION WHEN You're Wanting Ro John Martin Has It! Today, Rola loud speakers are hard to obtain, tomorrow, the world will hear through them! We still, of course, carry good stocks, but certain formalities must be observed before sales are permitted by the controlling authority. We shall be pleased to advise you how to go about securing a Rola replacement. If you are a dealer please advise us accordingly. Fia 5. The larger of the sheet pad bndala with lb. rivet n place, haslet ed fa.tete, pont.. Wind Iwo nunors of 45-B,ge x enamel wire op the bobbimn formed lhe two stator and the skies pi" f tnbe. Ito not. rorget lo sirve; the ange Is moth yheavier ')ange wire; here e. G v [obst. Also ce h that Ehe w entern end leaves the bobbin wee IE i6 Insulated. Use ')teat to e continuous, os ait Is keep the erlrr winding üoovnrdimla [o wind or 45-geu rra wire after dltcoverme winding should have pn nresistance from 4500 to 9000 ohms when completed. Insulate the outside of the winding wih a layer or two clamp ofeav wh'v tape galvanised gvanised r other 40n sis, wide around It; this z There are only two N.S.W. Distributors for "Role" and you con be sure that the FRIENDLY WHOLE- SALER hos stocks. This business has been built up on Service. If we can't fill your requirements, be sure no one else cant q AnoT`n ox /F. r x O.r. <nd.n rsrra,lwren,ez i^> n s<,,,xa ow Cran 3,re. Figu.e 6. Ills/P..1in, she consasälion al she ',Pole, the Anal shape of which ;t shorn by eh. 1hedinq. U.lseuld be shaped by,hand then he.dened by heeling end gssenähing wee., Finnlly magna Used lh es other of Ilse jigs, shown. See us for Rola Speakers, Calstan, Paton, University Meters and Test Equipment, Crown R.C.S. Components, Tecnico and Dunco Condensers, I.R.C. Resistors, etc. RADIO C ELECTRICAL SU PPLI ES CLARENCE STREET, SYDNEY Telephone: (ìw310') lt tines) Figure J. The leyoui end.ring of Ihu jig used so snessnefis. lhe al eels, 11 c,mois of s n boelllts see Sr. en iron ben and r und wish e guenlily el 26 gauge wire. PAGE SIXTEEN RADIO AND H0001E5 FOR JANUARY. 1915

19 Takshape n.mote., the mumetic cirant from one plate te the 0.10e. The u reedy for ensembi,. Then Ile' re made from piece of lin. thick.te tin. Senin. p t at eel m Yea oui end dolled as blown m spindle. mode Wm. n nne t. eneloa Any latele nit Nto o tertrunp to Me shaded par - fn. leaving slightly full for uture ou hiug up. The typed pate should non be tied ne that. whe n plated Use stator, t minmimum of heerte< between its mole. and nails which c T the Geld poles of the stator. Fieure O. A Menale mpeem'p ly,up anm. wedmeet.", eedy..e. M1N MI means ei rue. Ypa.teng Fe whale rohe :woke. doe. epeean:e.. Figure 10. A omelet Melt of 1M melee as it.r be 41...ee.p41M. 1M Meet pecans Mudd be es um..el. 1 ae ptuebe The minimum WAD.hear eee berme. N. rite.1' pm arm Ib. tips of Me relu. plane. PIeete Mewed be etely 1-ald.wpb. o peered.lerel4a mulaator. beet a gneun. ee loll 0 or le tolu W ine sunueill do A higher trite IN«thet10h. as illrúuam Ió Retier re S NT points are mapeiiwd In pried. at Mat three operation* ore necessary Y mag,teem. errrreaae.. 4r.e NIirk d the foimeaxlo e. llhe llr nn part we m arroi, Mem slid dip. Gm; e-. menue taro opposi. In tom nee. 1: f meek them els and 6 tum `m A N wto ;spored ndhe disee nd T eymy yt ;:4 end turn it slightly ao that m e pole Np e- / 1s /maws nor w. &memo I0122. amen. NM.., deep File. e. Danielle of IM roroleelt e.. I each arm He emu Breed wade M WA NI.." ball. Appe.ehnle paillee fee the ranee pole e Jae iediested. te evenly red mees nd gquenped elr. le Qtr. e TTY dull protect.rill render he plate mné.ra0k to retain the sell fermium 01 megnettunit INtts0Siy for erblee1 Opeeelbe of the motor.make as te topo hell the balance i wheel own l spindleind end meat. Tire. Ups ere eerh folt chp OolW drilled centrally In lite emit. of Ike Iln. 101,111.. Bolder the shaped Wear In Math ISONIY will n id n Me w to g yorllun of Iheelb-none note In mejee. You ill rem I U.et p'oket b that when nel.p,interleaved M Ile rein hut wev enrlep. A Title A I lee of ntllrun il. 4 wary 4 well woe rth while. An even the le elm desheble between the two sets f pole In the interns 0/10/00111 N,111 Before line motor»l efficiently the rotor Mate her to be manrnsed. This eld mlial up tome ti, Oln. t lili Ie ron nulls head. removed..set In hen Inen rm.e e latch rime diameter Cl lien Its belie 71 WO mime.. of sometheng nbe e-gange elre ere would nn Ibis Slq le the Manner IlltetW.d. When the Jld le r eadeed. ride rotor Metea!et on we of On une that boil. M the elide el the imam ems d or IR eol. Fee.. N. Ile camp». serer amebic. da.:p the mme petal.. wow, gut and np.ant.d 0.1 Mee pleb. Nate M.mep of lie lame. re - * Meese» the tleeedy `J.Need N tip IA Oft 01e Of M Ille *nee Mo colei IMetiw N4M M Imo aphn INy nmlly. ai, dire over.polo and when eoenpleel.d. roll enmmlé'nte e in1memo of N end t pone lips, one alter Inc other. rood the roles plue When memella,ilwe piece the die II gic100le In Amnion r o <onceireue of etwomn or lough it the were Y not omerhwllfa, CONSTRUCTION Insu remnae 1: Mole...atm.,/ te battery circuit. When the Joh of megnellaine the rotor ls tomp:ne. :he latter.v te hurried tetvlen purot arc 'crew, s after whim t It shoed `te ana» rondo.. on ao tel u althota mohlraa'.he n e0.! emetni bovnirg toy the r oedema t under holding the Jaeia l a :he loade oracketa. When Nie 240v 10.ey01e Ourlent le ayylied Io Ike rmahlg. a nick of 1M 11010e w 111e blew 1pod:ice =Lit to oy'mdtronola red. and nisi YbuW w1ue w reton. Id. ary. without the tuner.: i.e rut.. the lele< Cult should ta muse ha lot roule v for moo.edit. Meal Uw tmmr po:e n be ares rotor po:w till cause more t A :he :tarot om applied ta plot mints u M:pftl Meng completed motor. tk pet.tep b alum it b the eel The mat moetmeet obtained rfrom Owmen helm clock. Prom this eeerythio e tata pe removed except the Nabi of heels wnith nett aeeond hand spindle b the Mur and minute hued.. Meow It. A elm of the deer amenably. tab lb. teli b Ike Mierett el.ledeng. Wire der be mho hem wed «die bamfee.oe but eroe) un it te..mey fo mrianai. med.% and.nid eked. e hem. EM one.l.te Mudd be rabble wed Binh teebdr»ma Name IT. di Imitating eise, emu deelien lief,m dbe. his Me dti. Or eer wheelibe meoadiesd Met. Tb dp.le.l io.leb dame Mee Mould pro1me banm Ibe blew e 1 tb.bm N..pp Be emu tkned u Me maim shaft. 011r moine wer be wund to.voler al mpp toeral d Lcelú sm1 rlellnils thnr.tt this Ih<MeéiM hand epl le. which revokes e1 one re lalkm per omeletall minute. Mals ere u0n' therefore. In a eea nvutuma 11 0, to une rpm.,t'onitneed an Ppr I.1 RADIO- AND MORNES FOR JANUARY, INS PAGE SEVENTEEN

20 ADVERTISEMENT ROLA FOR SOUND SERVICE To make sure that users get service - should they ever need it- equal to the quality built into their Rola speakers, Rola extends a complete repair and part service through your local distributor or direct from the Rola factory at Richmond, Victoria. The Sydney headquarters is at 116 Clarence Street. If your Rola speaker cannot be economically repaired it can be replaced without a government order but speakers for new equipment can be supplied only on a Directorate of Radio and Signals permit. BOLA THE VOICE OF THE NATION Liven ragularly to Rota Radio Newsreel, the popular independent news broadcast nst this country, prey world a and Australian views in stirring dramati,atiom over 3X1.?UE, SAD, SP!, and 5SE every Sunday at p.m. E.S.T. - Distributed by: GEORGE BROWN & Co. Pty. Ltd. JOHN MARTIN Pty. Ltd. 267 CLARENCE STREET, SYDNEY, M.S.W $ CLARENCE STREET, SYDNEY, N.S.W. Manufacture/ and Serviced by: ROLA COMPANY (MAST.) PTY. LTD., THE BOULEVARD, RICHMOND. VIC. i Ill CLARENCE STREET. SYDNEY, N.S.W. PAGE EIGHTEEN RADIO AND HOBRIES EOR JANUARY. 1945

21 The first step to to obtain a half -Inch Whitworth bolt cut from It lh piece llnh -cdlong, this le drilled through the centre with a drill, to that it fits the rotor spindle. A little solder will locate it on spindle, after which the motor Is ready to attach to the clock train. th Figure pindtr amebly the essential an tareo details la Of sketch rof the complete multe. Equivalent photographs are shown In figures lonlv and coil ini latter is half -wound and the iron strap una the outside natureily n c beeun fitted. In the alarm portion of the clock, originally /crashing with the h t- and cute hands, you wnl find a 90 -tooth wheel. Next, obtain an eight -tooth wheel from an old clock movement and make up a spindle c prising the 40 and eight tooth wheels (figure 131. NOW drill holes In the framework of your clock so that the eight -tooth pinimt on the spindle Iflgure 13) meshes nene with the 90 -tooth gear on the second hand epindle. Incidentally the 40 -tooth wheel of figure 13 should not be soldered Into position until the spindle Is fitted to the frame This completes the clock train, and It is only necessary to connect the motor so that the w nu the motor connects with the 40 -tooth worm wheel on figure 15. Figure 15. A roar of th. completed cloak va Thu differs slightly GIs suggested loom r rangement in that lb. wheel meshing euh th.. o,m ic bet.een th. brass supporting plates. A mounting position behind the beck plle allows the mole, mountto well be- hind the legal of he face and hand. (In the 8 and 90 tooth wheels of figure 3 and the second hand epindle [ pecio ly), so that the second hand spindle will make one rpm, which le what we equire. This completes the clock movement CONSTRUCTION and, if you esmert It to the A -C, etart- Inu it you did the motor peeviosiely, y ran while you let tieing -la a suitable case. The IContinned on Page 41) Figure 14. Illushating the mplete wheel bait Pon, mot.. theft eto hour hand. 1f perchance the terse.heel o the second hand is of the 35 tooth variety. ]-tooth pinion will be required to ffecl the necessary 5.1 reduction in shaft iasd. Tile can be done in a number of Wipe. Usithem all b bracketsthe acct to the motor. posit in which you mount your clock train in left to yourn discretion and will, to extent, be governed by the type of ease youhave in mind A typical wheel train 15 illustrated In figure 14, while figure 15 shows the completed clock mechanism. The motor in this case is actually driving onto wheel located within the framework Of the clock movement. which necessitates the coil protruding well forward. It is a generally better plan to have Me driven when protruding from behind the that the motor assembly can be slcated well back from the front of the clock. Tne author else adapted the alarm mechanism to operate a switch control - hoe ioi c burger. This nor/cunt. fn ri an n1agvta al Cho right of the.lmk nt kie'ty 'evolutions of the motor WIII rake the mwheel spindle complete a one evolution, s Ivfe our cloak he worm ep d1 ao s rpm_ we t`lmive a mrtner eaueuca of s eo 1 A touch of home and happier times The need of our boys for entertainment recorde in so sal and vital that we ere sending them actually the greater pert of our present output. We are sure that you would not have it otherwise-especially in view of the present restricted production. YOUR DEALER will give you e Defies may,ypininin..hy she peraettee eeeorde yam,ones ere sometimes,anaeepnble. e "HIS MASTER'S VOICE" COLDMEIA PARLOPHONE DECCA REGAL-ZONOEHOMI The uiun.unonm Co. u.a, (Inc. in soptanal column. o apnmmuue 143at1 eh. ü. RADIO AND HCRHES FOR JANUARY PAGE NINETEEN

22 RADIO THEORY Recording and Reproducing PART II Last month we discussed the mechanical and optical features of the sound head, and we will w assume that a modulated light beam is effecting the photoelectric cell to produce electrical impulses. It now ns to follow these through the amplifier system to the loudspeakers. constructed and employ Inc floating, the latter being the gel, quality most popular with modern equipment. Figure Darn. type pre -amplifiers and main 1 shows Inc circuit diagram of a typical amplifiers r designed to operate en- Pm -amplifier stage. MR. L. B. GRAHAM they from saccumulators in order to The presentation of an uninterrupted Prinaipel of eh. Auu.eli.e Radle Calla. eliminate hum, While quite satisfactory ow requires the use of two projectors [his r a lternately. At me moment one coat of both Installation and malnten- projector takes over from the other, the FIiOM the photo -cell the signal ineern sound eisstems Perse[ sound circuit must be setehed to the 'maws hl Ille Dre-sniplllìer. The from the been d main, end have appropriate sound head. purpose of Ibis ploys ie In rp the eelebed to Ir oent.el' free from As already explained, switches cannot level hum be to a cp located n 'nt or e 100 vulpine between the photo -cell and antral andeiwilching, The location 0e me prie -am Pli fier pre-amplmer la because of the possibility an important ` The main point, regarding whic of introducing noise.therefore, each amplifier is designed to Work at different this level, designers have different ideas. sound head has it o n pe Amplifier, which ris approximated the I[ is desirable that the output of pie-ampllfler and 0ethemoot gee -aver device located a magnetic pick-up (about one be located as close to the photo -sail in to a volt). possible, in order to reduce Use possibility either MeCher pre-nmpllfiers asecting required. Since the output f the photo -cell Is of iosses 22nd hum pick-up, due approximately to long Somehave typesbean of.em -portable qmpone hundredth par!m,acting sass. t designed to decrease this value, it Is not practical lu use cost, milli and using only one adjustable components at tris low level. ON due to the possibility o[ introducingat PROJECTOR -amplifier. No set. gruhoto-need pre the sound circuit. bothc photo-cells no first gists it m eppanr that the brine permanently connected to the pre- -made switches and volume c und head itself is the most dedreble amplifier mound change in -over is accomgals may be regarded as aise -free when place; but this point is revltebmyaauh- plished the at pick-up level but would be ect to some vibration, which y be Thi `item ìs eldomter used Ì eorking ery likely to introduce noise at opine- reproduced m through the mlerophonlc Permanent installations. however. lably lower We.. photo -cell) levels. characteristics of the valve. The low output from the cells also Some designers, however, do locate CHANGE -OVER DEVICES ainful design thew pre -amplifiers here taking the pre - There are two change-over enders necessau y very and construction of the u prre-ampliyer. caution of mounting valve sdckets in devices. the switch and n the fader. The Possible forms of trouble are Hum. due sponge _rubber. prefer tom ont former use.= a two -position switch which to poor filtering d poor shielding; the u on the wall immediately in connects the main amplifier to either irregular anise, crackle, hissing, the protector, which keeps the souud ved a required Although the o eolanot valves, nosy resistors, high front meeting leads down ro a Ive niche aimpler of the two to operate. It does not sístance whigs joints, and ses e- in length.rah. lways produce the most desirable ance gestion between various v s pieces he ent valve m odoaeillol edeets. If icrophtg and the amplifier meshs. r the use in Where the change -over Ls between tae have concentraiotaetl hit Mtcrophoon, or sensitivity to mari a n- oit rely, having gamble of a 010. rent nature vibration, ís chus te almost ln viably modernd head it tohein pre-gmecó e c valves for u r and,u Oe g applications. Or a bue cal due and widely differing levels, the aiming transition from to level another 010 e'hus the pre gned. -amplifier bid m st not tea. sound heads with 60ì1r -in pre -ampli prove very Irritating. What only be well designed. but muet be very r d s ufgsuch brief a a period of The pueramplifier tien. after eon-pre-amplif le "fade out fade In. aduration as to be inaudible. may ode but sufficient to provide a smooth pony Orme change. raliv two trio triads or This condition is fulfilled by the fader, which is really a pair of volume controls ride éuffldent Iimpc Operated oue ntroll connects u is to the o ut put GrN4 ne co n of eeeh pre -amplifier. Figure 2 shows how this is Figure I. A pe..mplit., die single control knob being arranged, attached r ion to the c A.3 this L moved between e rapidly common 1 Ic position S. a ekeloube end aa wii- plil elk -nee -ever - n inhumed. A al rage gelignite guilt emilrol tar mien amain, Idol an burgher poi! In the gnu Net ea lard. 1: a [need r. then N. may be operated Ins vlb. phot lobe from het audnlnrinnt iciei adequate filtering A popular method of ting this end ac.pnlied'release!enrol is by, means M a smell. reversible within lh electric motor talad Is wired to a nlinga mech... ley-doeition minds located at n convenient point In Ne audnorlum. Toe PAGE TWENTY RADIO AND HOBBIES FOR JANUARY. InFo

23 person moniteeing the sound can adjust the Meth by moving.the switch into either the "lobe" o "hewer" position and keep it there until the required level has been attained. Suitable gearing between the motor end the gam control reduces the speed of change to e cdnveniant value. The main amplifier v 1p valve typos, methods coupling, a and with divedpimanetrers, nsical o iron to aloe pec1m mettliis However. since e. major dement r, high with minimum Ito ors o the output stage is nearly alwaig of the pupa -pull refs, dendriving eune a Push-pull circuit for the tlrtving stage as xell_ ells leone-eaparrty to a p010010r method f coupling, although trans - Thd RADIO THEORY Fiume 1. A popular form of fader u in fhe loon el e volume cannel citi fhe outer termine. rea gthe stenie, the metre culled and s.ea lace swap, f fhhe whole element. ere ar e generally used where it le y from single sided to change to ma rush -Pun amplification. Modern transformers leave to be desired little f u the matter of uniform frequency response, and freedom utpu distortion. The actual power output the amplmer depends the sire and acoustic ondulons t the audilo ern ewlth modern hlnh nosesna horn speakers the following figures a e given L show prover output required the Im different tlífterent seating capacities:- seating Capacities Power Output In watt IB It le important that the amplifier he able to supply the required power without approaching overload In any stage. The plifier system, Including the main amplifier and spare amplifier, with the, respective power supplies, ehangeover aevln motor-dal+en volume control, and n y power Swíteheapel generally Min on the rack and panel principle. The amplifier rack may be conveniently located against the front wall of the projection room, between the two projectors ft is to serve. projector Is tended from the right-hand side, so that the projectionist tending the lefthand machine will have the amplifier rack, with change -over device and othe. Controls, convenient to his right hand. The problem of distributing the (continued on page g,91 RADIO AND HOBBIES FOR JANUARY Post-war, the day will come when once again radio odd elecfrica) supplies and equippmeet will be available to meet all your needs. Meanwhile, we de our utmost to consider you, valued customers, coil to r fulfil essential orders. MARTIN delaunay PTY. LTD. SYDNEY-Cnr. Clarence and Drina Sbeeh Al 1691 le gene NEWCASTLE-Cnr. Ring end Darby Streets B lines) BUr WAR LOAN BONDS NOW PAGE TWENTY-ONE

24 A D V E R T s E M E N T PORTRAIT PAST.. OF THE Remember when you could go to your radio dealer and ask for. any R.C.S. v Kr \T'_r component time you ago, tainted but -and those get it days are without any coming back trouble? It before seems very a long long-and when they do, tronic whatever the apparatus. industry demands equipment R.C.S. will in the required. be ready way and of new baiting radio with and There'll the elec- J:_.,_ be exact...,,., one big type of v., L_:.. jur.-- diference ever your though. made postwar set The R.C.S. ials. and be/ore. tout be coil. new That's ideas because new better than..,,, have ---, been methods of anything developed K.G... and manufacture, have new mater. laboratories to meet Service requirements-and the result is a wealth of knowledge and experience that will be at perfected in the R.C.S. research YOUR service with Victory....C.S. S40 GE TWENTY-TWO RADIO PTY. LTD., SYDNEY, N.S.W.

25 found to the audience is probably the biggest one, on the reproduction side, which the engineer has to tackle. Closely linked with the number and type of speakers to be used are the acoustic properties of individual theatres. Having provided a satisfactory frequency response up to, and within, the speakers themselves, the problem resolves itself into ensuring that the resultant sound is equally distributed to all portions of the auditorium. In the early days of sound, large moving coil cone type speakers were most popular. These failed lamentably in the matter of sound distribution. The reason for this is the "beaming" effect of high frequencies. This results in high frequencies being heard in their correct proportion only at a point directly in front of the speaker, or along the line Of cone axis. The reader may check this effect with his own radio by making careful observations from different angles with relation to the speaker. Other serious defects of the cone speakers were low conversation efficiency and limited frequency response. Efforts to improve frequency response and distribution were made by using a large number of speakers. These measures were only partially successful, and the Three voce of exponentinl hovna Fig. 3. Multi - cellular horns with something like I B sections are employed to ensure even distribution of the higher fre- q u e n c i e s throughout the auditorium. V rapid developmental of the exponential horn, driven by a moving coil diaphragm unit, made possible a new line of attack. The establishment, by engineers, of definite standards as to the requirements of loud speaker systems, encouraged much useful and experimental work. The result is the modern high efficiency reproducing systems capable of fulfilling practically all the requirements originally laid down. In listing some of these requirements it is pointed out that they were laid down around the year 1937, yet there are few systems, outside the field of motion pictures, which approach them even today. These requirements were: Frequency response fiat within plus or minus 2 db from 50 to 8000 cycles. Equal distribution of these frequencies over a horizontal angle of 110 degrees, and a vertical angle of SO degrees. An electro acoustical efficiency of 50 per cent (an ordinary moving coil cone speaker on a flat baffle ranges from 10 to 15 per cent) Although no definite figures were given the system was expected to come within the limits of reasonable size and cost. A system capable of achieving this wil now be considered. Separate high and low frequency channels are provided the cross -over occurring at 250 cycles. The low frequency unit consists of ont or more moving coil cone speakers, working into a dual mouth exponential horn designed to load the speaker efficiency down to 50 cycles The problem of distribution is not serious at these frequencies, and the design of the horn is Figure 4. A +ypice frequency dividing network es used in' theatre loudspeaker systems. Constants very with individual amplifier designs or special acoustic requirements. not critical, apart from providing the correct loading. Since these speakers do not work above 250 cycles they are designed with heavy thick, cones. This practically eliminates problems with resonance and harmonic distortion, resulting in a much purer reproduction of the bass notes. The high frequency unit consists of a cluster of 18 exponential horns driven by a twin moving coil diaphragm unit. Each of these horns is about 27 inches long and eight inches square at the mouth, tapering to 0.5 inches square at the throat. They are arranged in three rows, of six each, one above the other, with their throats converging to the common driving unit. This arranges the horns in the form of an arc of approximately 110 degrees. The high frequency unit is particularly effective, and results in practically equal coverage of all the high frequencies over the entire. auditorium. A complete low frequency Unit, using four 15 -inch cone speakers in the low frequency section. measures approximately 12 feet square by four feet deep, which is quite a reasonable size for use in a theatre. The separation of the two frequencies takes place before the signals reach the speakers, and is achieved electrically by means of a dividing network. The circuit of this is shown in figure 4. CHANGING OVER This completes our discussion of reproducing equipment, but doubtless the reader would like to know something of the procedure adopted in changing from one machine to another without Interruption to picture or sound. Obviously some form of cueing device is necessary, and this generally takes the form of a mark on the film itself. In the silent days these marks were generally made by the projectionist, and since each projectionist had his own ideas as to which particular frame needed to be marked to suit his own require - ',tents. films very rapidly became mutilated. The system now adopted provides that the cue marks shall be made with the film and are standardised, both as regards their position on the screen and distance from the end of the reel. Each cue mark consists of a small "splash" or dot occurring at the top right-hand corner of the screen. It occupies four frames, so its period on the screen is 1-0th of a second. Two cues are provided, one occurring about 10 seconds before the end of the reel and is the "motor" cue. The second -me occurs about half a second before he end, and is the "change -over" cue. In order that these standard cues may cork satisfactorily with machines whose notors take different lengths of time to reach running speed, special leaders are provided on each reel of film, This is opaque film, but at a point 12 feet from the commencement of the picture a single frame is marked `START." and at each foot from there 'o the three-foot mark is a single frame with the footage number clearly marked, RADIO THEORY The projectionist then finds by experiment which footage number he mùst always place in his projection aperture to synchronise the arrival of the picture area with the "change -over" cut on the other machine. For example, No. I machine is nearing the end of the reel, while No. 2 machine is loaded with the next reel in sequence, with the correct footage number in the aperture. No. 2 projectionist carefully watches the screen for the "motor" cue, and as it appears switches on his motor. He then watches for the "changeover" cue, and as it appears operates the change -over shutter and fades the sound from No. 1 to No. 2 machine. (To be Continued Next Month) NOTHING IS IMPOSSIBLE As far as radio parts and valves are concerned, we have probably the greatest range in Australia. For all radio and electrical requirements, write to DEN HAMS (M'bro.) Pty. Ltd. Maryborough, Queensland. RADIOMAC NAMEPLATES 4d. each. IT e hare the!allotting markings in stock at present A. BATTERY AERIAL ATTENUATOR BAND -SET B. BATTERY B.F.O. BROADCAST C. BATTERY CRYSTAL CURRENT EARTH FILAMENT GAIN GRID INPUT KEY MICROPHONE MILLIAMPS OFF -ON OHMS OSCILLATOR OUTPUT PHONES PICK-UP PLATE POWER POWER -AMP. RECEIVE REGENERATION SHORT-WAVE SPEAKER TONE VOLTS VOLUME WAVE -CHANGE ALSO CIRCULAR CONDENSER & VOL. CONTROL SCALES, 1/- ea. RADIOTRON DESIGNERS' HAND- BOOKS-BOOK YOUR ORDER NOW 5/- ea. PRICE'S RADIO 5 îr 6 ANGEL PLACE SYDNEY RADIO AND NO981FS FIR JANUARY, 1945 PAGE TWENTY-THREE

26 ADVERTISEMENT ANOTHER WINNER FROM UNIVERSITY UNIVERSAL SPEAKER & OUTPUT METER... We anticipate the needs of radio servicemen, and produce the precise instrument to do the job to a nicety -every time. Here's another thoughtful line pioneered by the makers of "University" fine test gear - the Universal Speaker and Output Meter. An instrument which makes set testing quick and easy. No power connections required, you just plug the instrument into any type of speaker socket. Why not read all about it and other "University" lines in the descriptive folder which is free to you upon request. k' r-.-.. The `University' M.V.A. is an all purpose Multi. meter giving complete AC/ - DC measurements, together with output meter rangs. Suitable f o r either bench use or as a portable. 'University' of. frrs an eynn s i v e selection of -meters which includes volt, meters, amulet meters etc. 111 a complete range of sires viz: - 2in., 3in.,.lin. and Sin. T h e 'University' Supertest - er is a most versatile Valve and Circuit Tesler, (cater. ing the extraordinary valve!1 Ti 11 1 n1111e11'e1 rillet le -t chart -entirely new to A u Ualia. Does many jobs wrll. DISTRIBUTORS: VICTORIA: A. J. Veall Ply. Ltd.: Replacement Parts Pty. Ltd.: Hartleys Ltd. QUEENSLAND: A. E. Harrold; Homeeratts Pty. Ltd. SOUTH AUSTRALIA: Nekton k MeLaren Pty. Ltd.: Radio Wholesalers Ltd.: Gerard & Goodman Ltd. WESTERN AUSTRALIA: Atk ins (W.A.) Ltd. TASMANIA: W. k G. Genders Pty. Ltd. N.S.W.: All Lc a dine Radin and Elcetrleal Distributor,. VICTORIAN AGENT: J. H. Ma era th Pty. Ltd. MALII0 ICAIIpHIrg p`12?a ICD, Head Office: 206 Broadway, SYllNEY. N.S.W. Telephones: M Telegrnrns: "R:1QUIl' Sydney PAGE TWENTY-FOUR RADIO AND HOBBIES FOR JANUARY, 1945

27 RADIO THEORY EFFECTIVE HOME-MADE ROTARY SWITCHES In building up test gear or other radio apporatus, one of the most serious problems for experimenters is that created by the shortage of rotary switches. Set out below are a couple of schemes suggested by "Radio Cr Hobbies" readers. FIIiST suggestion conies from Mr. R. G. Graham, of Wonlhaggi, Victoria. who is using home-made rotary switches in his unillíh id er. Mr. Graham sent along a specimen of one of his switches for our comment, and the positive nature of its action certainly leaves nothing to be desired. General method of construction is illustrated in the accompanying sketches. Obtain first a piece of kin. or 3/1610. Bakelite and cut out a 210. square. Then, by drawing diagonal lines, locate and mark accurately the centre point. Using this centre point, set the dividers first to a kin. radius, then to a lin_ radius, and scribe two circles on the surface of the bakelite. On the larger of the two circles the contact studs will ultimately be located, so that it is wise at this stage to decide Just how many contact positions will be required. By arranging the contacts with an intervening angle of 22.5 degrees, there will be 16 positions all told around the circle. Any other feasible number can be arranged with the aid of a protractor or by stepping off the spaces with dividers. Ultimately you may need a switch with shorting or non -shorting properties: that is, one which will or will not short out the adjacent contacts as it is turned from one position to the next. SUGGESTED SPACING If the switch is to be of the double pole type illustrated, there will be two contact fingers, and the contact studs must be exactly 90 degrees removed from the appropriate positioning hole. The 22.5 degree separation works out very nicely In most respects and can well be followed unless there are particular reasons against it. In any case, give the matter careful thought. Having decided the point, mark out the appropriate number of positions around the outer circle, then scribe lines from each point right through the centre to the other side of the larger circle Now proceed to drill the required holes around the outer circle, being par - :...+n.+.. ra+aho rn maintain exact centre. Use an eighth -inch drill for preference. (The common 5-32in, drill gives too much clearance for ordinary hin. radio bolts.) Brass bolts do nicely for contacts if the heads are filed down to give a flat top. Small solder lugs can be put under the nuts on the other side of the bakelite and the protruding portion of the bolt nipped off and flied flat. In fact, if brass nuts are also employed, the leads could be soldered direct to this flat end surface. Contacts way will be of the shorting variety if the contact leaf is made wide enough to bridge the intervening dap as the switch is rotated from one position to the next. Shorting sections are usually employed for multi - meter current ranges as a partial pro-.tection to the meter, For non -shorting contacts the holes will need to be countersunk and fitted with countersunk brass bolts, the heads being very slightly below the surface level of the bakelite. Alternatively, auto brake drum rivets or similar can be employed. At this stage the centre hole may be drilled of a size to suit the par- ticular shaft bush on hand, In this operation' it is better to err on the side of to osmall rather than too large a hole. for it. can then be filed out as needed with a rat-tail file, and brought to centre if necessary. The actjial bush used will depend on what is available. A suitable one can be turned up on a lathe or else made up by sweating a thick washer to a short length of tubing. It can be riveted or screwed to the bakelite as shown in the drawing. Alternatively, the bush and shaft from a discarded potentiometer may be em - tontot! J.npeTS insulation er Flush Contort os for.eltago rang. tolle. m.eta...,nb boil Bokeure 8ose Contact tmngr u,ae "t Sol de lu / te, fleribí9e teacl / Ptessuq prm lotattnp a u Psotrud.ng Contort for current tonnes Bush scrwo«or bolted m plats Main shaft oos.t,onn9 notes on ad,us ployed, in which case it will be mounted with the usual lin, or 7-16in. nuts. The chief requirement is to have a minimum of bush or. mounting nut protruding through to the contact side of the switch. The next step is to obtain a small piece of about Am. brass or mild steel to carry the rotating portion of the mech- A Single -pole rotary switch constructed by Mr. Graham along the lines suggested in the article. grass bolts are employed for contact studs, being flattened or countersunk as required. anism. One hole will need to be drilled, a neat fit over the end of the shaft. At. a distance of sin. from this "centre" drill another hole large enough to provide clearance for a lin. steel ball. Two other holes will be required in the approximate positions indicated, these being tapped to take the assembly bolts. The contact fingers should then be made up, also the necessary Bakelite insulating washers and tubes, and finally the pressure arm. The method of assembly used is exactly that employed in an ordinary multiple -pole phone jack. In fact, parts from such a jack may often be employed. When this preliminary work has been completed. take the small brass "carrier" and rivet and/or sweat it to the end of the shaft. This may need to be done with the shaft already fitted through the bush. The underside of the brass carrier should clear the surface of the bakelite by about I-16in. and the shaft should rotate /freely with only the merest trace of end play. I A/'ATIAI!_ DAI l Drop a 3-161n. or lin, steel ball Into the hole in the carrier, press it down' with the finger and rotate the shaft, so that the ball rubs a faint circle on the bakelite. If the work is done accurately, this should coincide with the sin. diameter circle already scribed. Now proceed to sink a series of Ain. diameter holes in the exact positions where the line traced by the steel ball intercepts the radius lines previously scribed. The merest touch with a larger drill will then countersink these small holes sufficiently for the ball to position itself in a positive fashion. If the holes are not in a true circle, the hole in the brass carrier may be slotted slightly to allow a certain latitude in the radius path traced out by the ball. Arrange stops where necessary to (Continued on Page 27) RADIO AND HOBBIES FOR JANUARY, 1945 PAGE TWENTY-FIVE

28 ADVERTISEMENT ' YOU'LL BE HEARING MORE FROM US...and more of what's going on around the world To Austral, a neighbors, brought closer than ever by short wave communications and the fortunes of war, Hallicrafters sends greetings. You'll be hearing more from us --and hearing lots more of what is going on all around the world through short wave radio equipment that we will be able to supply. Hallicraf ters are builders of the famous SCR -299, the mobile radio sration that speeds ashore to coordinate the attack. It wosks either stationary or on the move. Intensive war experience gained in the development of the SCR -299 will enable us to continue to build the finest short wave communications equipment available. Hallicrafters' line in peace time will be bigger and better than ever-and certain to include the kind of equipment you want. hallicrafters RADIO I ICR.,t,Rf COMPANY, n.n. I,ICTtoNIC BoU,P.,tNt. CHICAGO,, Y., A. PAGE TWENTY-SIX RADIO AND HOBBIES FOR JANUARY, 1945

29 ehu CC l tlions ROTARY SWITCHES the.efm the prone.toa ó h contact Continued RADIO THEORY Mount an ordinary octal wafer oats et on the panel of the appanlus. nions the trente and the lead from the to allow the switch to rotate beyond the anal titre. pusttbns. S Men valve bane te rho circuit to be switched. enter should be bent s' fflclenuy to up the rbpper Main and had Rushed -posi- Insertion the bale M different pna tuna positive contact. while the pees - "I ln me keg snakes wfferenl ec- Ma, arm Should beer down on the Mil fork 'oln all four heave. If everytmn is arranged properly. the match will be found t ehetictemoivbg rco tlona Internally. The var1ul pontoons common M identified by cutting a tch In ca tn tet he valve bate and fining It with *lute to have a very recise action. braving nth paint. room im doubt a. to when the u millet Rom Mr. R A. Jeatnp. o: Derby. Tag - Rather almlla h the :deli of n the m treat lasta!aty. Manta. tolites the lnllowine idea' 'late Inµ sit octal c other w onee These latter. by the we5'. tge:)er with an ordinary oral valve mm and!rind panel of the apparatus socket brinµlho presort ae rim. nay be made Iron off the key so that Ille locating pin is the lewd to be switched out Iren the therms, Mouse perfectly round; the be!e all now much centre Ire {transepts.. sprint. Remember bock* In an mutton. Uralt tht at. li bronze often hs Wain hole thee of the In IL tithe like wood, and must be cut aetag pip led pte a lennthgh of hook' and bent with this in min. nd wee Ihnndh it. ore end hetµ Poe but results. II*.enter leaven be given a boll point Thin can managed by prnupt the Metal Metedtt of the.tel Is oper with a Theend phone top Or Other sala able plue arrangement gementhe hile eta - eerrnn-lly ve art irked Inú reof quited. The COMM MP be ro a fmrlla.:a' pin inside the completed es desired by intentai the Moe Mee. Wet Iota the approeelale 001e. ate a tin. steel ball or, alternatively. sweattn. or riveting a mall. reaped peen of metal undemem the Up. Remember pro C. I lug II to which neale Made can TECBATICAL BOOS REVIEW bbesmarted. There i Marble leads are ben anchored :o a "EI.F.CTRICAL AND RADIO NOTES The book to freely Illustrated thtougllatall0nery lue e:sewhere on the bakel!'e FOR WiREston OtiS11ATOlt9.. tutted loll dale for lctllating Use Mae so as to minimise chances of ntr,:n by the Air Ministry (litai from Ind dlath mnalons of and aerials and feeder array.. breakage. The general design per-!ro:ere ttot offtre, rotin Du mon. 220 (Our copy from MerRll'e Agency. Aiv- :mitan price6'] modale parla and l faetlltese t apdroa.), bem-street Melbourne.) neallami. but. p.m*. with tare, Me result le pesityyume it. not a mere el,-thisd shillings, In actual fa. ct the teneral dimensbos book auul0 be hard to beat fora ven- "Oro HANDBOOK FOR WIR11.E99 ta be ',doted wtbout dtheully to dewed une for radio enthildu:a The OPERATOR" Published by ADM point where Use o oì es Ba C.onery Office BUR er suppo rt ares 7IIndamn-eon moue. the Admiralty Handbook and(while llt 112 pages. Australian 1 price Y It eon be supported on the (tent pa Panel e pproathn the subject from an elemen- ppmro elth b) the e bush or lacy vitapdn' careful reading 14 ates neon- Tr. bolt. IS Well known. constituting a long e0uleleeaunh bol[ through my to extract the full value of the standard r each toner. MM. Ia o t manual ftoe eadne eedutetoh Ien add- The switch shown la the am4npatp- In mg photograph U of Use Ville -pie sanely In -men no Iosulat IS tn. MyAWbetween k seem the book A eonvetilre e. mglter al. the basic structure of oig of Was and mdloteiegrams over molter then u '.Ils and batteries, ahld and More mittens Ho âv*ming he emné4 Mad and leotruments feiett= MmHb the method of posluapag nee aired, u d Inductive Amateur Then mitt! Btatron their do caeca and ait IOaUag current. to peruse a espy óf this boot Much donated. Choler e teodueeo tus lheemlonle i1l the material will not dfm:ly apn:y. valve and thernllt the test cintres but the rldo 2 will.notd vote. under- So much la the ;on of of remgnbea building eomnarcw a around Its sppllentlun for..redan and Dros tun. However. Me colmab, ceduc[ bea.mplinitteon d In Ivens and oe ppaemmd.e Interbt our n: be me a meet) on ua1m hick opt directly Ierlahnun. final chapters deal nain heeinieu t.he borse t I salma b the lob teoh:red Of It. A Btle.erTh and will often rfiake the International Morte code. the a e supplies great of information ab ona a O anpumity kllslaetoey hob o1 conversion.pouuf4 In UM book. end the reader who abr. ndaareogaued Inl regarding e Drrlile.. Aarr:rktll:e, NSW. Mlle eorbld 11 all Wld be 11 on he y how required fwr from Melitla 7 poetico rotary to thorougnswiltadon h understanding t radio switch for a m lt:meter which area under nd AasbOYJ t ttsnehon Unable to nu:chafe freroo a lwt- W. Agency. ldmbethion -e;rne Ole unte. he Managed to get hold of a Melbourne.) 'TIME BARER. 'Their IYealne and.'pole 3 -position r; g:e-bank nysdey. Deve! me B' O. B. rurale end proceeded to moony at to Il his 'THE ARRL ANTENNA BOOK." By AM3[E. Htrerfh SDep,rment. A- C. (èe'rg. Ornmm.r aria Byron ants IL Oosaor. Ltd' cloth rover. 2nd pages. Amlian Mr. Deelna' -I removed Sher of Published 1912 he American Nllwd pike 22/-.l, pttetete W. the motile eon:acts. leaving o only. Icrlav Le,óue tin paper cover. 1fa T:It t Infotewed beck.es n- a flattened down one of :he te:oppers Man. AUUnllnn trice '6 atiprpa.l, ocele been reviewed In 'Hwdlo and pongee Cd. ' olerhaving been palel, ed bp. - As Stressed In n the foreword, Monte/qt. Maya. Chapman and Ha11, LenaOn. Transmitters out s del of 'The ropy f0 ha, os been Wb - HOLLYWOOD AND and energy into their elver Ihhed In New York m Jane Wflep and and noonti ee, Iv Ìlmh ultimate Bone, welch nta for the dlearane THE DECIBEL mutts by lnadeouste attention to the In price. The teat of the book Y en. aerial T_atalatlon altert. however. has M thud book, the ta'o perlt Ha ils -known Af[er l Ihry atthlrr cello re Vnomod n:o {pecalisln In a vet tit ehitat cold m exam pit Preis, ppourorr n boycott)y ppgnod br Uit pace a oulpi Simple and (b ii which nite gimme io the1-,,fdpropertfn M et the del various circuit eel count OI lead. eeb000ei by,u a pinny metro It appcaeo tr 'reciruinblo soft mime. elel the feting of some (Mods. amateurs e pee; has :pit mule r trigger Inu polar co i Iamb but application. rue to war cow oscillators. dcircuits. ne Mt of note. and MOM. during Midi óf a 'rad to ant Id.Mclean Ée advantage tilt and veloq[y mocwatlon Tonle lea sequence It has thus become who t pvmeegrt and Hsu. to makea p ire 11 the.save et W U to,its on the Tien aree sections n tools ideeer- Mot lon hem push-pull Pltboom. "tminh"o funds Dnlriny lite Ynllmmer, trimmers Wove clam. tt'nchronise:on. arts the ile o1 lims l a plena,. entitled -Mt Winkle Prulmtallon. Antenna FundametnWK llrne bases for frequency CI5'Ubn. Ill fines To War.` 200 soldiers had I nt Oresund rneels and Feeder eaten. the alppandicee there Is wealth of. Mnebire lamb ebete' beretoe Its elan The mermen* nine chapters del alli formalbn relative to rnuedn-rep he1na Of Me Denim Fehmn1 O llommon and aaltumal lynes o1 MMnllrnfr selcy and l operation Hobert Armllmne lead to talk durino Inrltidme lbw he the Toler IrIgo.ney An excellent eooellent hook for myooe ho to eatemps noe e pond noel 'Deere a M make g speck' study de of mashed 'Melees Pon tee Ìtc thl yo expect t blurt Our copy from stcrall:'f colored Mtn gravy. envy, W bemuse of ab. aling runty. and enealv:nt aerials. Age4.) ' RADIO AND HOMES FOR JANUARY, leas PAGE IWENIY.SEVEH

30 foundismr ; lle ikely RADIO THEORY RADIO VAEVE DESIGN AND APPLICATION ARTICLE 12 ryal-, when the grid voltage changes Having to date d d considerable attention to volve charac- -5, the plate current is the teristic will leave this subject for the time being and when the grid ltage -15 Op the plate current is 1.SmA.At the [one aper - pass on to discuss grid bias and the methods by which it is most poet BI under c dltme, frequently obtained and applied. The importance of the sub- ttie" he urate a a sma. ject con scarcely bs d. Comparing results. It can be se en thatc - v grid might well TIlScontrol be the grid, It will cause the voltage to Leon T1 ldith jimelhcf called the most important single swing between zeronnd -10 volts a tirs swing. it Is only thisor electrode in its effect on shown the diagram by the performance. light the same change 5 volts. line. causing corresponding s plate curt is the input element of the valve In other words, an even rise and ent variations m 15 end 5 A, respec- fall ln and signals normally introduced to il add voltage Is reproduced tively, by e uneven and fall f plate those which. the valve is required At the Operating point of the curve, enrrent. r nett result le that tre o amplify. which represents the steady negative the eì'nal a n L Irulh(WÇ' ampll- In peaottcal]e every pw lcatl nn t Hed end dlamrlion le intmduced, valve ae an amplifier, a tire control grid, thes.ntegativ18 portion of theu In put cycle This Is simply due to an excessive for efficient operations must be kept causes e decrease In plate current from negative grid bias, which results in the Initial negative l 10 tos ma, difference of 5 ma. On valve operating on the bent part of the with respect to thefilament. Tl his I s the positve half of the cycle the plate grid voltage-plate current curve. called the negative grid, or "C" bias current rises from 10 to 15, a change of The actual bias voltage required for Rage, and Is generally defined as the 5milliampe. the correct functioning of triode valve difference between the grid voltage and Therefore, the periodic rise end fall is determined mainly by the plate voltthat at the negative e d of the valve n the a1 voltage c solar age and load ana by the strongest Infilament, or at the cathode, when no vert plate current, which con put signal which thé valve to signai is being received. bidon Ir ideal to If, with no Incoming signal, the grid ted handle. Ls returned to e ]oint ate voltage more toe eut From what has positive than the negative end of the filament then the grid will let s< By C. E. already been said, have e posi- happera when we It Is apparent that tive bias, vert this operat- the bias voltage NEGATIVE BIAS ing point ana BiiChmAi i must be et least apw Icor- ne equal to the Similarly, when the gid return 1s con- greatest peak of nected to e point morenegative than If we had z o bias to start with signal 1 voltage. Unless this Is so,the the negative end of the filament, it Is and impressed Inc 5 -volt input signal positive peak of the signal votage said to have a negative bas. This, in under these conditions, the will cause the grid to become positive, practice, is the usual state of affairs. old grid e gild Main purpose of this grid bias la to I volts would to fluctuate o current. ive and 5nd lt pool- 3 -volt peakrise input signal requiress at set the petfltmg point of the valve live. But en already know that it is least e 3 -volt negative Mas, a 10 -volt near the centre of the straight portion t desirable, under ordinaryro dl- signal. n 10-volt bias, and so on. curve when sig- lions, to operate e valve withpositive a However, It does not of necessity folof It e chareeteri tiic grld voltage. Hence, sere bias Is not low that valve will operate properly By havin g the operating tn satisfactory, unless there happen to be with e bias determined only on the entre of the curve, the pp point ion the o special circumstances. bees of a certain estimated signal in - put signal to he grid causes Then, again, take the case of too high put. It is necessary to check this point the grid patentai to vary nd steathat h oint down toend or- negative move cutabulated data or to the c apply a 5- eppropriate p curves. during ehis mhiretialte. is, thesgrldtage be- signal, the grid oltage lit comes o less negative, due to the flvolt uctuate between points x and o-that BIAS AND GRID SWING alternating nature of the signal. Is, between -5 and -15 volts. In doing Before dealing with the methods of this, you will notice that the lower bend of figure 1, the straight Portion Ithe ass obtaining this grid see e of the eu vc has been brought Into using ferent ]bias vo ta ges. theof Ynam ic cu extends opetat nr r regiov. approximately from point A m point B. with its e at O." Clearly, the In figure havevoltage- valve could be operated at point 0. reatypical grid t0 presenting volts, be plate e weent capable of handling an n Input signal of e willuseforu our up to 5 volts peak. Maximum grid swing discussion. weld then be 10 volts, Let us assume that the correct grid bias for the The tenu parr- 'grid wing" often creates IS titular curve is -5.0 volts. confusion se regards its exact m anmg. Thus, point "O" old the curve É It actually Indicates the extent by would be the operating which the voltage on the rid vales point, which means, with no ith the incoming al that Is the incoming efgn 1, the grid le lntialle 5 volte negative with Iotb pwitivef and negcrete. ative h elves tf W respect to filament minas. It df the a- c signal a input a peak input 5 vola Is now signal impressed my,n The maximum Permissible grid swing s then the re ge of grid voltage varlabon which will not cause distortion,, either by r ea of The gild becoming Figera I. An Eg.lp aurae 4 positive or the can signal volmg which... to illustrate As _reaching the lower bend area. importance of choosing the If we maned the grid awing of e lut, and not certain valve as 6 volts, this would vc slworking a. itou me mum mean that the potential of the gr id grid swing. would vary from 3.0 volts above m 0.0 voles below some fixed value, thus giving a total grid swing of B volts. The wedu hyoelehe On once n e finptteti ellaoto, PAGE TWENTY-EIGHT RADIO AND HOBBIES FOR JANJIARY, 1913

31 Inmaximnee one. the. ee. g.s volt swing la generally referttd to smarm. gm solmgav Merit winding t In Ma way. each valve s`in`peak tome Men Dee term geld Vien( leas elm been taken le Indicate the de peak baatttmre iesrrequire biased without pmlodic went. of ionn`ifrom t he erhe o a InateaO of applying rwowh, Elan re- diee<t to ferencedne. Rom mit denaltlen. te Id blot `tete cathode at It bviously be teen that he grid =u äinite 0 developed had. e cathode. icy would be bal' that of une former Eta with the mm Ilan in. 3.0 volts. However, to grec return a por tential. For this eart to be poaaible. elther mold mettle..d min nndernd. mft IM. 11 e Ara: definition e ae hlm type getera1v the valve moot be lure, o a Morne t type irlth a heater endtnr one toot to matron grid mktg. when Of Its Ille letter nennlllon ie used tor she lean -peak voltage'. Te boar circuit for Mott.cathode- Amway. he:her one sate Mel lite bias le 61100n In Ag. 3. M you will gate. the «motel component es into RC valorconnected Ethan the ln.lode tar earth m' B-mmoe. ebael00e e and T he am parts ot inputand output R*mute nepet0rele. Rgae Ind, hougn presented esmelon- Roo of Ma u met ewe. need not lemmata, be M. In l derived teem b.t- lull practice. they arc Olen toil of one type or awiher. ere. med ed le kred anvek Let ut see just how this rnl000r Re Co. provide Lhe M ramble negative er mg. grid grid sums P. e volts l the peak rbothle ne jxesrsemin ees the am n` indeerent manner. thetnec are grid 1Ów`11 Ir of pea oler salve. but he Amplest form `r0 prob. barnan Mos. bolery lee 1óÌ nragn uv ellaier.ve ermtnel of the ballery Malls ode of Stor ne a aected ngst the replan lead goes to the grin circuit. The grid is Mlle at a potential wet with respect to Me ntament ` Inre ts terminal. To prevent the ntalrlla lfloargie applied to ha grid from being nbtl-r:r led o Alament r a the teas battery. It Is memory to have.ao r form of Im - resistance the turn dread,. We fed rt lhe ge nneeerall y taken the form either of a cell or reaketon. one end of which u c0nreettm to ee geld Itself whilst lilt Other goes to the source of bas. The bolier, used lot' Ihin her of hid network oftenhas number 01 epimitable trust a one P of mers inn order remotest may be booed oft. The M`eown gene 2 will week< Mae muneruas o clear. type MeritMe- Valve u one using smame- Allure 3.In heuéem `at carrons ason miln more in the direction Indebted by Me 0e L Mee. within the valve Itself. we know he Bev lo be Iron cathode to plate. The eurrcpt flet tee call it I n. In Bowing hrouith Re. will Rum a voltage drop ocress It equal to Ire Re: the ir'41:1 Aelem.,.al.lee,. the el, tar,lah es thaw. sets avitese drop the w. llsr e e ethede ie repelti.. t atld. dun eh. to earth, o which the geld e lrtumed by meting of the rntelar Re. ed. ntnu Item oe normally no add turn -ni, the Oeta WBI be at Me same m :!tr nth. Ream. Ihr cathode mint he palnve with mde4 tr. Me gran by the ment mmlnt It is pout:aw well meet: to Crean In ether words we ate have lite geld negative went respect to the lhax end se Have gala requited bals. SPECIAL BIAS CELL That, easy aetb, ea't It? Now rie havethe negative While on he Reject of dtrect bid. frill Ebta. let sr whate happen:, when a aimai Intent mention that Ihke bid M a ao <ttmes obtained 2 o applim to uo rida The Input.lanai the bee of I. *eclat end-rolallyy Ikebaltet,- are 1led across Imtlel:vU er:nuve to the beet renuen Yreferred V as a Naas' coihode Et ate veltea. drop when Ineered In he acre. Rc. the Input genet will simply r eel!. n e vent provide maiden the Mar emen1101 of I te 1.5 MILL grid te become es los nega tive: that talkare rarely.sera In his donna. LLrovld pine the signal doer are frequently not exceed the geld bid. to be found In ATM,- Ott the peeve boll of Me cycle he Ica,, a equipment. Aï the buttery abed* ` rid potential will become let negative an ob. tot respect to vlotl5 means of obtaining the Wm, theca cathode, with the late rryy Mat anm1es.::a. te motntr n alrle:m eer This sr"nmtnâeten. ry re<elven Now gad Pale ae.tn e type. 11 Ands on cement will came the voltage drop Peleten 'umbeler re - ro tie impellers serum Re ltd Leu Rn to e- the plate) Peoneiesn lee dogisert dgem Ì1nn. In he tom of mint.oemled neap. Ilse Monde bermes ne tuwnite. eyeing Indlerlly-hrathl Veer.. a On 11e negate. ball celle Of tie.e in wodern pmellm, set new tee...guide I111.1 etar:l Çeee gal aka plat,. h im le genteelly ObtaItald be nuero 'file Mote current dm sued lte needed. of the m9 value In Ile kner IÌ1í" 0011x0 cathode lead of he reeve. The es a drop acres, all soma Ro u deteple m palm and nn be employed al ear emnante. Mader Met In the cam os pnellmle one cathode cenumemee, Ile plate becomes more RADIO THEORY Poetise. he cathode less pansa relahio toltearth. It e lines merent nut, under the influenceplate rie the a Input Mane. boat and cathode posa. tlae Om. theplate thvgew of Srld and anode ottentials It le voltage a: the01111 cathodenuo with respect respct te 11: Ix yy ew Ilh the Input vor- 10 heal tine utpul ile ne norm out of Wutre. ]he vowel wett a»made Mall ne vowel Ope roman. an we Mall now sea. The voltage which Y.Beam e ope - une not._anryrj_ he red voppee ogress OhIlt bal rag. as Orw at eat hat woened. pprra err,ppera GRID man Ae 1M the nearpol dem_ IenUsi alto`vaariiíes in 11011, ao at U:e erech'e voltage M- imeo g erid and cathode mus: a:west ue Vas the Input agree by the eut- aga deteloped emceeemceero. Thes Is a form of degeeentico or negative feedback which manna in the gee Of he stage beings redurd. t. nee Uri Input voltage 4 not fut.» elfeeun in Operetti1oryl he aine. retheme/re. negative feedback ttu'..e effect of hrthe Internal or a -e..:tance cf the valve. REDUCES GAIN current n.'. Mint In ampere and It that. es Aloe le agate ttahou feedback 4 ner.ses e amplio canon of une vane, It LL d edve nl a0 eo:ll The voltage drop In ill: d coto ttea Tseogu0 ba nu make eh.. eot p Men that pee: gec.m en:lnhm!avc Mg Me cond C menus ile shown ma.he e0hn, unaffected d Mee terrain, unchanged. However. an aoon on W, o a received. the reign e tan > cllat d by It. The following leottr show how r o Ms takes piece - The Tl :e beat ntlimpeddering the matter e he basis or impedance. The delle: C.Vann reactance when it I veut Uwe resistor that the Impedance ImpMaxe O[ the b lower nun eut ut::en I[ enter.i :he condenser a large ttlnufh, Ira Rpm 4.7o ma Lot el udo pet Nratk dpamn Mew 1a the mlmde emit. `o.0*0d` ia hpm m- ete employed en Jean. Newasl Wee ie irai to 10 old. irti tee vere motel. that a myen a -c plate current wal develrrrop e r n.tr-rly sweu s lt hore:ue. be Irtleacr nag:: tu oppose the awual and the negative feedback k effect e!f ct 'ill be small lima the nettante of :he condenser pclrr r:ttmol to Its topoody ht atltnteenthe current. i amate :Is neecrherf Úx condenser' tarde eramet In to ma nrtme te be nn emad at ex howrtt fnimetcy required, If an even omplt- Malenn of audio OMmeleee la to be era lined. In eadtte envr O tm15110 migale fusee 8 lo f is me.11te moulders forw, i rreguieaelel I. 111`1ÌÌe ame t'` of I -P and lhn eletti he ala rid Inoqu e ntes ara Bere MM. the aste OC..Unmd en Next Pam RADIO AND ROHM KM JANUARY. lois PARE IWENTY.NINE

32 1 tt RADIO THEORY RELEASED A limited number of CALSTAN MULTIMETERS For Essential Users and Radio Service Men. A Strong Compact D.C. %Multmeter guaranteed to be within 2% accuracy. Small enough to be carrted In a coat pocket yet with sufficient range to cover all the needs of Radio Servicing. The Meter: Gelstau model 01, thin. round flush bekelire rase. Voltage Ranges: e-00; u-511; 0-236; 0-12,0 HO. Current Ranges: 0.1; 0.10; 0-30; 0 23 Milliemps. Resistance Ranges: ; Ohms. Finished to an attract - Ive black castoff, complete with test leads. ZENITH RADIO PTY. LTD Palmer Street, Sydney. of 0 a generally 0.1 esta., although sometimes 0.5 is often used. So much then for the theory of operation of the cathode bias circuit. Now for the actual calculation of the bias resistor value. This is done quite simply, providing we know the required bias voltage and plate current, since, in the case of s triode, the cu t flowing borough the bias resister is equal tu the pl Framutthíst information it is Pat. a natter of appltio; Ohms law fe determme the resistance value which will Figure S. The sosvonlional sailnrinnyegnet for bark -nie, in Note nthat the R. fi r,g the. cond... i, not aerlhed. 3 grue the n cessary voltage, and this s done by ing the formula R equa s E/I. to which R equals resista In ohms, F equ I5' bias voltage an volts, end I k the l te cu ent In armer s. So, if v havea triode valve egvir- Ina a bias e of 10 with a ploie ourrent of 2,5 tna, determine orb bias resistance v Ive. Substituting known values above equation. we have:- In the e:- R WOO Manie. Thu la cmrtiderably less [tau the value required valve 01 the three above. Fr or mample ,5 x ohms. There Is another method of blasing which Is quite often used. especially for output valves, a. this Is generally known a ' back -biasing:' Actually It is a farm of direct olds, in that we have tite grid return of the valve being em - noted to a point negative with renpect toinnellie cage the negative point is obtained by wiring a [pot Vulve w resistor with the negative lead of so maower the voltagey drop across It is equal to the required bias. Since the oat negative end of the resistor will be that connected t0 the Whet supply, the god Is returned to th is point. widlet the e l earthed to the chassis. These actions a shown In figure 5. In this position. the total cu ent drain of the receiver p s through resistor so that, when its value this must be bone r, in ayou ill sn ttee the resistor Is not by-passed by a hand nser as necessary with the c thole bias. since in0he majority of es the hig tension filter condenas provide an adequate return path for tl a audio frequencies. However, in the case of receivers re - q :ring a low hum level, it is metimee adve raga to u additional con - ' R = 1000 d has across the bias: resistor. a value = T1000 ge mid[ to 50 mfd being quite salire coo ohms. f netoryo. ntalley, in ing up this Thus, If 000 ohm resistor w form f bias it is essential to connect cted W the cathode e cuit, the eq- re- the main filter as shown. sia condl ionse w be met. otherwise the ripplereie from the reeiined Freeque thy, the Interests 0f a -c can set up a hum voltage across the ms-,. the grid bias voltage for several r t elsmr. salve of the same type, 0 valves oper- This form of btu Is aim applicable ating s under similar conditions in a re- to battery receivers, the mangos being ceiver. obtained Horn a single resistor connected in series with the E-minut instead [s of supplying a separate bias re- lead, sistor for each one. Since, in such ease, the combined SUBTRACTED FROM H.T. plate currents Of all the valves now It must be remembered that the back - through the bias resistor, its value must bias voltage has to be subtracted from consequently be less Ivan that required the high tension voltage. In the case of this Ingle valve of the same type Thus,, can be a mpeosated loaincelvers. If t we s have l similar lopite valves power supply design, but. w have only bat lashes of a r the same bias resistor. the.re. dewill fiwhere volute it. he twice as much plate current relines a direct Iona In flowing voltage end output. through the resistor, ist0 and c rseg handy only one-half thenormal rmalre ot -stance might be expected. there are other vaine will be required. wa of providing the necessary grid In bias notably some cases, it m be desired to grid Imes t bias and A.V.O bias-or use a common sister for valves which that applied for purposes Of e quite dissimilar, yet requiring the automatic volume control. However, theseaseare nllclth mid bias. l, rl: rather special cases, which will is oe be dealt certain the total anode 0'727:2 with at the appropriate time. c ing toe the valvess, concerned and, knowing are From Me designer's point of.e th reqvalue biaresistor Olatehm than eastry value of Ohm's law. ec type of bias employed has to bview. chosen with full attention to its Influence core example, ambla ui may have tocan performance. a well a convenience aft valves, nm.n requiring tin Initial maintenance. weer, standhowever. e n e be.anmbegs clan[ we tl the the need of - 5 rolls illi drawingrespectively 0, l and B ro m bias :mine lue 'nd bias and Ilur usual methods cf vante of the total bats reels tor. npo. Off le. Obviously, a, oral cathode ue ill mi111amps, so that function of tht e triode the revswtit'kllle se III nplfer. ante and dogs ires best at a higher vound frequency than man, and they can hear higher note., buta rat can hear higher atilt. PAGE THIRTY RADIO AND HOBBIES FOR JANUARY, MS

33 st Istence RADIO THEORY COMMENTS ON THE PNASE SPATTER THE phase splitler used in many general salve having liedinlron c cuits is in retails, pllfi 'actor more desirable than one having a very high quite a old, having been v ver low amplification fame A well tried out mar v number of years, The phare splitting stage, vulve with a very high amplification tie populaety dunce r ant years in which hen been a prominent factor has a limited grid swing ami UAA lies ew ver aliea, f e of am pli- limited Elate swine find may overload of the amer irccan when used to drive a final stage having preference pehis seer ilia i triode circuit. fie rs nt peon, yeo, hos a high grid bias, such as Mal triode This twin [renie circuit is capable of come n ta.a certain aa ont valves. In at any ca port from this divider, in en co, en very unlit of criticism of late. In the point g ectlÿ adjusted bu It requires iresaccurate gainas bv increasing the amplification h ment of the tapping fallowing which feeds article, Mr. F. above about 20. the grid of the second half of the twin Langford -Smith of the A.W. A valve having a very low amplificavalve, Unless this adjustment is made Value Co comments on the tion factor fe.g., 6F6 -G trinde or 6V6 -G accurately, the two sides of the push- teodei s less desirable the repull amplifler will be sut of balance. characteristics of this circuit duction of distortion, dueto negative If a al tempt ü made to use fixed arrangement. feedback, is reduced by the reduction eistors e voltage divider in place In amplification factor; thus the dtaof a cartable adjustment, there will be...ion would be slightly higher than eases when the mismatching of the two 'th high pii t f toe nrthe twin triode valve itself is sufficient to noticeable tea by dividing the whole load re HIGH OUTPUT? - balance. (stance r' tins ras.l m gohmt It Is for this re together - There are, however. c in which It With s other minor disadvantages he empliflcation factor of the vale n sears to use a valve IN low Which need not be stressed here, that n this ca 20, tintes e cathode bit amplification factor, or when It le e 'tor oy this cirmataloe le not recommended by the s50o0 hmsl. i ThiI typa [ phases titter. brase very to power ten g A.W. Valve Co, for the home constructor. a y low w resistance r _ between grido and M1 Ive f the clrsef n cing It le tl The chase e litter wllh Nemen t, such as 1 OE" 2A2 S0 on P agas s Inherently self -balancing, since tir plaie a tl ealhvde teed rn ces fixed bias h ant that haws though the cathod Inherenllp balanced and don sel a otter -s the same the titiste This ll E,v e, suitable a. the cool Raring e etba beyond en- hat flews through the plate load a Rafle valve, and L fact al u v labl 46e two [nlstan are sal an that grid tyage the very is graonsindependent of the velvet true label. flowing)_ and the na rein voltage r strong reasons for the use In rise roe circuit A50a it will rbee soli station or the load such circuit, tthat gives v that these two smillera each have Ohm's Lew, egret eue Curren cal anent performance. peofoa. phas 'Ilia -ie e provide rhertance r[ megohm, while e m le llea ba the resistance. obefph cal analysis f phase Stage resister of 500- ohms Is ltea e- We thus have a type phase s an. rather cbe and e ly he. piston bias, feed grid bias r welch arty finherent a results soles will be here. fstwe does net Heel the balance circuit could hoir Ite inherent homme intuit. resistance r Is much high r between csame and de of between the two ended Inc valu- than tant for Comehi dreary he load, the grid the [he second amplifier Pstage is only [ the values of d something like 1p tim 116-Gunction output valve te fed Emme the two resistances andrni ü not in any w Incresistance o( Incgrid resistor. i_ With ic erlov d[ the megohm ooee ias affected rte the valve which in need. s grid of 1 megohm, a estoc alla the 5000 ohm cathode bias Any type of triode valve, or pentode been A50a, the Input resistance d ait ptedosa a triode, me be used In of about 10 rems. Tels n beneficial y would seco d have been possible to feed this position a with se tlsìdcecm pro- affects Inc bass resparise for a gìvea he second 6Vpna afreette from the made te eue necessary adjustment is athode of the phase eplfttrr valve but, made to the cathode bues resistor. IComiuneA nn Page 301 in. this case, the o a rash adnte would have had fo RADIOT RON 13 WATT AMPLIFIER ohm, megohm, that 6J7 -G 6J7 -G 6V6 he whole -G between arth and the point from which the taopthe taken oft to the following grid is 05 megohm. In passing, the cathode resistor be eco - The Redielren ere eli0er e t AYH,e AR, le which relerenee Is made le the e ttercon, perky., fiait conditions ter the output valves we slightly diraient from those moloyed. the RSH 12 watt ample Aar, but The p fermente el fe fire is subsseme,liy the éoy. sn WITH A 1,ANSFORUER nano er 385 V. R. Om, 12 6V6- G A504 e. caeea - RADIO AND HOSSIE FOR JANUARY, INS PAGE THIRTY-ONE

34 CONSTRUCTION SOLDERING PENCIL FROM AN OLD CELL COMING originally from a German source, the idea was brought to our notice by one of our readers, Mr. R. E. Aitchison, BSc. Mr. Aitchison made up one of these soldering pencils nd found it to be an entirely practical proposition, and one of great potential value In servicemen and experimenters alike. How many of us, who have no electric soldering irons or power mains, have to tinker round. with the gas ring or fuel stove before modifications can be made to a receiver or amplifier. -And how many, -who possess an electric iron, get impatient at the time it takes to heat up when we only want to solder one or two wires. As often as not it takes as long to find a place to plug the iron and to heat It up as it dces to rectify the fault in a receiver. This soldering pencil provides the complete answer to the problem. Simple and cheap to make It will solder rapidly and efficiently and does not consume power except when it is actually in use. This feature was much stressed In the original German article-for rather obvious reasons! It does not require to be tinned; Just an occasional touch with a coarse file to maintain the proper tip shape. Figure 1 shows the essential features of the soldering pencil. The soldering portion is a rod of carbon, split down the centre and insulated with a small strip of mica or other heat resistant Figure I. A stick of carbon, split lengthwise and insulated with piece of mica make a up the "element- of this electric soldering pencil. Yes! We'll eat our provers iai hat if this isn't the handiest little radio gadget you've seen in a dozen years. Costing practically nothing to make, it requires no preheating and is ready to make or unsweat soldered joints at a moment's notice. not essential to the operation of the unit. The rod from a standard cycle battery cell is about 5/18" diameter, and this can be split lengthwise with a hack- saw. Rest the rod in a groove or on the partly open Jaws of a vice and seek to make the cut as central as possible. File the two pieces flat and note the end at which the cut has been most nearly central. This will form the tip of the pencil. Obtain a thin strip of mica, as from Now file the tip to shape and test between the contact strips to see that the two pieces of carbon are not shorting. Punch two small holes through the contact strips, thread a length of power flex through each and solder. At this stage the pencil may be tried out to test its effectiveness. To avoid unnecessary heating of the rods and undue load on the voltage source, do not maintain the contact longer than necessary to make an effective joint. For convenience, the carbon element will need to be fitted with some form of handle. A way which suggests itself Is to wrap the binding cord with a couple of layers of adhesive tape and then clamp the assembly into one end of a metal tube. A handle can be fitted to the other end, with a hole to allow the cord to pass through. This cord should be no longer than necessary and incorporate a generous number of strands, to avoid undue loss of voltage. VOLTAGE AND CURRENT As previously mentioned, the voltage should be from 4 to 12 volts, obtained either from en accumulator or a transformer operating from the a -c power mains. Provided the primary and secondary windings of the transformer are properh insulated, there will be no danger of shock. It Is Impracticable and unsafe to use the mains voltage applied direct to the carbon tips. The filament windings of an ordinary radio transformer are quite O.K. as a source of voltage, but some experimenting is worthwhile to discover the best arrangement. The usual 5.0 volt rectifier winding will do, but more "kick" would be obtained by connecting one or more 2.5 volt windings in series with it, the insulation. The assembly is filed to a blunt, slightly rounded point. The two carbon sections are suitably mounted and connected to a secondary of a transformer delivering from 4 to 12 volts with an ampere rating as high as possible. Alternatively, the supply may be from a sturdy accumulator. In use, the work is smeared with soldering flux and the pencil is pressed down on to it in sucn a way tnat the circuit between the two carbon tips is completed. CURRENT HEATS CARBON A heavy current flows and the tips of the carbon become extremely hot. as also do the wires. If strip solder is applied at the same time, it melts and flows over the work. A little manipulation of the pencil spreads the molten solder and covers the work as necessary. The technique is therefore different from that normally employed but it is master. But try the idea for t easy to The carbon rod can be taken from G discarded dry cell-an old torch, cycle or radio B -battery. This carbon may be a little greasy, but the grease can be removed by heating the carbon over a. flame. However, such treatment is Figure 2. We tried out Mr. ',ache - son's suggestion with the pieces of carbon tied together with string. For more permanent use some form G'R) MAINS of handle would be desirable, along the lines illustrated above. an old iron or toaster element and trim it so that it fits neatly between the two pieces of carbon. Cut two small strips of thin brass, zinc or tin plate-say, 11' by 3116"- and make them slightly concave so that they will fit the curvature of the carbon rod. Bind the upper portion of the carbon rods with strong cord. with the mica in position and each contact strip touch- ing one piece of carbon. If the binding is continued tightly for about one inch, the whole assembly will be found to hold very rigidly together. 4 t 12 VOLTS phase being adjusted, of course, to effect an increase in voltage. Two 6.3 volt windings may be connected in parallel, the two going in series with a 5.0 volt winding 11.3 volts overall. The higher the amperage rating of the windings, the better. This usually means heavier gauge wire and therefore less d -c resistance to limit the current flow. Remember that you need a reasonably high voltage (around 8 to 10 volts) at the highest possible amperage, and with as little d -c resistance In series with the element as possible. PAGE THIRTY-TWO RADIO AND HOBBIES FOR JANUARY, 1945 i

35 e i. CONSTRUCTION may care to rip the d- mfrom an existing oddment trans - forme, formen winding on a secondary with the COMMENTS ON THE PHASE SPLITTER heaviest I possible gauge of wire, (Contloued from Pane 31) If such heavy gauge wire is not obble, two strands of lighter gauge sire of coupling condenser from the cathode and earth Is not sufficient to stirore wire can be run on side by side, bang preceding stage. result ln an practical inure In dis - ay Connected together at the start d The whole stag is "hot" and any tortlon over the hole =Oilier. Ionian, Alternatively, two entirely sep- attempt to measure voltages across A further aspect of the phase splutter arate secondaries v be run on a d either cathode cor plate sections of ere the s that the output Impedance of the a eted i parallel. - - cathode section of the load resistance cotthe he writer nused this when and a valve tnitmeter Is Ls different from that of the plate secquite a lot ]ot a recent weeks ew ge end The preferrer method checeing tl- tion of the load resistance. This is io Position to Pass On a fax general is eilher by measuring the start of brought about by the negative feedback hints, output valve gild tees rent with e and those who have studied this sub- Remember that the operation at the,ter', a n aeforme circuit r ject will appreciate that the cathode unit out bye then woo or beingushortede two separate transformers or chtakes -action rs b=cet to negative outage, feedback while the Mate feedba em by place of a centre tapped tra.nstarmer. molten solder, so that subject ofto al current a firm pressure Is essential. TREBLE BOOST EFFECT The actual formulae for the tee onspot Sore support resistance across these ive pas [ is therefore desirable A capacitance connected between the the load resistance aie given on page d underneath the work when soldering cathode of the phase splitter and earth Ofm[ehre loose wires together. ther. This be pry - has Ahdeiot brdsinetoh Lhe elect [ c 'ng treble b00st^ lode, t N!k by a little strip of black Iron, itio n the other side ofthe amplifier; tracent tnpeessiens Duly, on which Due can also place a spot of yen the very small capacitance besolder. tween cathode and heater is sufficient The point will be found to ble to give a slight amount of treble boost ANTI -RADAR DEFENCE gradually during me, Mile. deposit which c very small degree of TTNFOIL stiles, long hoed by ai emit part or unbalance, a t a high audio frequencies n both sides to fall plane -locating therlipnanda preventlr ratty t. Keep only between the two sides of the pile - appoca his, employed m Old file handy to correct either pull stage. a manner bygermans. ethe ditian. This small unbalance at high fre- Formerly strips were droppc Try end keep the thtckncss of the quencies only is of no practical im- from planes, filling the air with strip two ee'bmi n plat the same. portance, since the power handled at o0 metal which apparently confuse The mica these frequencies so small that the operators of ranging devices. The new shoo appears to distortion is negligible inn se; Ni ae "weapon, u first used on the in ay the point. ne -half of the amplifier could easily so thatcrumbleit is not likelyfort getfin road. vast. front France, works in th handle the full output at these fre- opposite direction. A box about a fou It would be entirely feasible to wire quencies. even If the other half became square Is shot to a height of 6000 to receiver a solder- cothiis Inoperative, 0000 feet. It then bursts open an ing o of this nature, at tbughh one tendency trebe boost- releases a bunch of long, silvery an hardly prefer it for this purpose ing has been used as method of pr'o- appareeoe m talhn strips. twould o au ordinary electric soldering iron vidlns a "treble bons" farm f tone It se obvious these are In But the penal has it all over control which has been described in tended bas e. defence m e agaice when a couple of joints have to be even., periodicals. Even the large the undisermit Allied device soldered in a hurry. for it does not Rumour ut by require env preliminary heating,. a falily f unbalance which bombing Ietge Capacitance abetween through clouds and fog. Replace with CROWN "UNIVERSAL" ->" 7 Adjustable Coils Crown edjuste boa inductance "Permatune" cosh e e designed to.plea Ih. Eoa.da.f band wit. in wrachully any recwver. When.n Antenna, R.F. sr Oscillator cell requires replecement use. Cease Universal Adjustable Coil. Universe, "P.rm.wni' Cells ha continuously v.ri.ble in induct.nr. ever wide r... M. coils.ill ly "track" with the ether coils in Ihe n Properly adjusted. The exact induct.. inductan el the old cell easily matched be. eery simple edhohnent of Ill variable Iran Core regardless of the value of the tuning wand Crean. Universal Adiuewble roils ore urallnbbe at Din Cruaw Iiieeri beggar s. 11h - 71-R! IDURRRY STREET'/ PS 17/ROUT - SYD11E11 YOU CAN DEPEND ON Crofcn. ADJUSTABLE COILS RADIO AND HOBBIES FOR JANUARY, I945 PAGE THIRTY.THREE

36 DX NOTES BROADCAST BAND DX The closing weeks of 1944 have proved a little disappointing for broadcast bond DX'ers. Poor signals only were received originating in parts of the world from which better things ore usually reported during our summer season. STATIC has been very severe so far this summer at our listening post. It is hoped, however, that we may experience a few good nights during the coming holidays, when we will have the opportunity of spending a little more time than usual at the receiver. Mr. Roy Taylor, of 2KM Kempsey, was first to advise this page of the reopening of the Mudgee commercial. 2MG, which, as many readers no doubt remember, left the air In 1041, having been In operation then for a few years. 2M0 is operating again on 1450kc. sharing the channel with 7DY Derby. The present operating schedule is 6 pm to 10 pm daily. :MG began its present service on November 13 last, securing the services of Mr. John Tarts, former manager of 2KM, from November 1 Mr. Paul Buckingham Is manager now at 2KM. An ADXRC Victorian member Is quite proud of his verification received by airmail from New Guinea, from the Armed Forces Radio Service unit. heard operating on approximately 1323kc. This station is the headquarters apparently for AFRS units in the New Guinea area, and the address is APO 322. We learn now that the call sign for this transmitter is WVTA. and not WVPA. as listed last Issue. Another ADXRC member, stationed in New Guinea, advises. via ADXRC. that the call sign for the transmitter on 1418kc. is WVTH, and not WVAM, as at first believed. The location of this one Is Lae. and we understand the quality of transmission from this and other AFRS stations Is not nearly so good as that from, for example. 9PA and RAAF Rndin, Milne Bay. From the above source we learn also that the latter station has not been heard lately, so it may be off the air. The Bougainville station appears to be on 880kc. nowadays, and it Is believed their call sign may be WVTI. All WV units announce as "The Jungle Network." Our thanks to ADXRC again for the note that New Guinea time is one hour ahead of AFST at present. The authorities decided in remain on summer time, when the mainland returned to standard, early In Fnr those of yen able to hear WVTA 1323kc., WVTH 1415kc.. WVTC 1450kc., and the outlet on 1480ke., we find two calls listed for this channel, WVTH and WVTD. A report addressed to Armed Forces Radio Services, Arms Post Office 322, may bring a reply. We advise listening for these stations at night. perhaps around 10 and 11 pm. "Tune In" reports a station on 1320kc., Ing its address as APO 77l, this one having been reported by a listener in New Guinea. This may be one of the Pacific. Ocean network stations. In this group we rind suc stations as WXLE Eniwetok, Marshall Islands 1320kc., WXLG Kwajalein 1440kc., marshal's WXLH 1400kc., Makin, Gilbert Islands, and WXLF f STATION NOTES AND Mr. Gaven Kelly intends to have every Australian broadcast band station verified by Christmas. We certainly wish him luck, and are looking forward to see how he fares. Gaven, at. one stage of this escapade, sent out 50 reports in four weeks, which sounds very much like hard work. The attractive pale blue and navy blue card from 3KZ Melbourne, our friend's favorite station, Is one of the latest cards in Gaven's collection. The station call - sign appears in pale blue on a navy blue background In the centre of the card, and' the recipient is advised that 3KZ is always interested to hear from long-distance listeners. 3KZ, "The brighter broadcasting service." employs studios and transmitter 1600 watts, at 40 Victoria -street, Melbourne, with head offices In the "Strand" Building in Elizabeth -street. 1340kc. Tarawa, also in the Gilberts. We have received no reports of these PON stations being heard on our mainland yet, but it is likely that some of you may be able to log one or more of them. The old favorites, Noumea 075kc.. Guadalcanal 730kc., Espiritu Santo (New Hebrides, 104Ske., are still heard well at night and around 5 am, with SPA Moresby. Auckland, and Munda sharing the 1250kc. channel. Munde is free from Interference on Sundays around 5.30 are Also in the mornings, apart from the many other stellate likely to come through from stations in Europe, listen for the BBC AFRS on 513kc.. and the American broadcasting station in Europe. on 077kc. Reception from North America appears to be a little disappointing,his summer. KPO San Francisco 880kc.. KSL Salt Lake City Utah, 1180kc.. KNX Loa Angeles 1070kc. t under BWB till the West Anat. closer amt. KHJ Los Angeles 930kc., KOA Denver. Col., 850lte., being among the old reliables still breaking through, with DX reports for the February issue should be posted to reach Mr. Roy Hallett not later than Saturday January 6th., His address is 36 Baker- % street, Enfield, NSW. quite a number of others. known to most n you. A couple store Easterners from Mr. Moore Include WLW Cinclnattl, Ohio. 7001te., heard through 2NR's signal at 9 pm with news and hillbilly stow at This Is the now 50kw. Crosley station, which sometime ago car ded oui tests with a power of 500kw WRVA Richmond, Va., 50kw. on 1140kc. also reported by Mr. Berndt'. and WSB Atlanta, Ga., 50kw, on 750kc. were copied around 8.30 pm whilst. after 3YA Christchurch closes at 9.20 pm on 720kc., the "Chicago Tribune" station, WON Chicago, Illinois. has been heard. Victorian, Stuart Kerr. 1s certainly making the best of his opportunities whilst serving with the RAAF. He was on the spot when 3CV changed from Charlton to his home town. Maryborough /with the transmitter at Carisbrooki, and met many DX'ers during his stay In Adelaide. A few days' leave were spent at Canberra recently and our friend was very interested In the many things he saw there. particularly the studios of 2CA and the regional station. ICY. Stuart did not visit the 2CA transmitter at Gungahlin, some four miles from Canberra, 'along the Vass road, but says the 2CA building in Mort -street. Canberra, is very attractive. Two studios are employed for normal recorded pi ugre «,plea. c tna h1 it c:aptct capable of seating over l00 persons is available for audience participation or live artist entertainment programmes. 3KZ-2BH VERIFICATIONS Mr. Ern Moore received his verification card from 2BFI Broken Hill after waiting for almost 12 months. Running a power of 200 watts on its frequency of 7901:c., 2BH is owned by the "Barrier Miner." a Broken Hill newspaper. with A white card is Issued with small microphone in black with small flashes of electricity coming from It at top centre. Station call sign appears in black letters in centre of the card, and a few station notes are shown. Broken Hill adopts Central time. 30 minutes behind AEST. The writer would like to take this opportunity to wish all "Broadcast band DX" reporters and readers a very pleasant Christmas, happiness, health, good DX, and, perhaps, ocace in i 2CA sprang from a 50 watt station, using a small back room at A. J. Ryan's radie shop in Kingston. Canberra. as a studio, back In The present 5kw. transmitter, working on only 2kw tas licensed i, works with quarter - ware, self-supporting aerial tower. especially Imported from the US for use et 2CA.. After climbing a narrow staircase to the second floor of another building. Stuart found the one studio used occasionally by 2CY. A young lady was in attendanc and explained that. as most of 2CY's programmes come from 2FC or 2BL, the studio Is only needed occasionally for the few programmes coming from Canberra. 2CY Is on 1050kc.. with 10kw., baring been In operation shire December BL COMES OF AGE During the night of Monday. November 13 last, the Australian Broadcasting Commission devoted about 25 minutes' broadcasting time on the national programme to a feature in celebration of the alst birthday of Australia's oldest broadcasting station. We were disappointed to find auch an important event in our country's radio history receiving such relatively meagre intention. It was on November 13, 1923, that a test transmission was carried out from a 500 watt transmitter. using studios at the top of "Smith's Weekly" building, In Philip -street, Sydney. A studio concert. annnllllced for November 23 was duly broadcast with such personalities as Mr. George Saunders. baritone- and Australia's first radio announcer, later heard on 2GB and 2KY: soprano Willa Hokin, heard still on the national stations. Mr. Saunders and Miss Hokin were among the pioneers appearing in the anniversary broadcast on the national programme mentioned above, as wits Mr. J. M. Prentice,Uncle Jack t, who must hase certainly been nne of.he world's first radio news commentators. Sie end Uncle George Saunders were very popular. we understand, whilst they were together in 2BL's earlier children's sessions. Mr. Prentice was last heard front 21.1W. but Is off the air now, doing, we believe, a One war job. "ABC Weekly" reminds us that an important part of an announcer's work in the early days of broadcasting, was to play about with his musical chimes for five minutes or so before the commencement of a programme, to enable listeners to "addle abnnc' with their rate' whiskers, crystals, Re. This avoided the need for adjustment.s after the show began, We understand that in those early days. gramophone records were often played into the microphone from the old-fashioned gramophones, until the adoption of the pick-up, used today. From "ABC Weekly" we learn also that for their opening trar:tmission. Sydney Broadcasters. Limited. used the call sign taking the firm's initials for their call sign. But when Farmer and Co., Ltd., opened 2FC on December 5, listeners complained that the call signs were confusing, so 2SH adopted the second and third letters of their firm's initials, BL, as their call sign. It was not for some years that and 2FC were amalgamated. the Australian Broadcasting Company being formed in whilst the present Australian Broadcasting Commission was Inaugurated in July, A newspaper, "Daily Guardian," shared the ownership of 2BL In 1223, with Sydney Brand - casters, Limited. Both concerns have gone out of business, as far as we gather. The large city atnre operating 2FC is, as all Sydney - lies know, still to be found in nur city. CCAI rl' CCT Crur,AC We feel sure DX'ers would not have appreciated the sealed set scheme, used for a time doting To overcome the financial problem, a listener was able to purchase a set, enabling him to receive signals from one station only. The listener was able to choose the station to which he wished to listen, and was compelled to pay a licence fee to the station to which his receiver was tuned. Stations asked their own fees, by the way. Broadcasting, as we know it today, began when the Westinghouse Electric Co.'s station. KOKA, In Pittsburg, USA, broadcast election returns on November 2, Other experimental transmissions had, no doubt, been carried out before this date. The first regular broadcasts in England began only oeie year before Sydney came on the air. Station 2L0 London began on November 14, Back in our own country, we found stations popping up like mushrooms everywhere. 3AR Melbourne, Associated Radio Services, began on January WF Westraltan Farmers, June 4, 1924, &c.. Cc. Radio 2UE Sydney is our oldest existing commercial station, having been in operation since A complete list nt Australian stations now in operation, appears elsewhere in this issue. PAGE THIRTY-FOUR RADIO AND HOBBIES FOR JANUARY, 1945

37 SHORT.-VAVE NOTES - BY CONDITIONS GENERALLY GOOD The Festive season being once more with us, we would convey our greetings to readers and thank them for their co-operation during the past year. The standard we have been able to maintain has been very largely due to their efforts in this direction. WE hope this siklh Christmas tinder war conditions will prove to be the last and that, by the time the 41e xl twelve months have passed. we Will be celebrhling a victory which 1105V feel us assured. Conditions over the past month are good and, although there are few new stations to report. there is much good and Interesting listening to be dune. With the release of more and more territory from the grip of the Axis. we will find stations appearing which have been or/ the air over the past years. The latest of these is Athena. which lias once again appeared un their old trequency of heard 5.30 am -6 am. Another transmitter was formerly on the air on 70751c from 4.45 am am. We will be glad of reports on this transmitter. One of our readers has Intercepted a Morse signal from Athens at 0 pm on the 9036ke. transmitter. The call was SUM. as of old. The Swiss Broadcasting Corporation are now radiating their service to Australia and the Pacific Area from 8 pm till 7.30 pm on 12,9671m. and :c. Both transmitters are heard at good level, and we have no doubt that a letter to the authorities at Berne will bring results. Tuesdays and Saturdays are the days to listen, the transmission on Tuesday being entirely lu English. The Western Australian Short Wave League are holding their DX contest and. if the logs received from Mr. Matthews are any criterion of shat Is being heard over there, the contest will be a great success. Listening Is being done round the clock, and stations from all purls of the world are heard. We are sure our readers will be interested in the results which we will bring to notice as they arrive. TIPO, Costa Rica, is heard at 10 pm at fair level. a station which rarely comes In at this time of the year. This one may be the forerunner of more signals once the summer lx over. Reception from this part of the world should be an improvement on that enjoyed last whiter. Most of the American stations on the air at present are reported this month by Mr Kelleher, who Is getting fine results from them. Recourse to the station list will show what Is to be heard throughout the day and. among them, are some of the outstanding stations of the month. From the same post we learn that Algiers is still being heard. The transmitters on 010kc. and 9535kc, have been under a cloud here, but are now on the Improve again. Brazzaville Is heard well In the morning at 8 um over FZI on kc. and 9440kc., and again In the afternoon at 3 pm. News in English is heard at 8.45 am and we can heur them here till 8 am. Very tine listening has been done by Mr. Edel, who was the first to hear HH3W from Port-au-Prince, Haiti. The station has been mentioned several times In these columns but. until recently. had nut been heard for some years. Mr. Edel hears It un kc. at 10 pm and, despite the interference put up be strong Morse signals, has succeeded In identifying It. French is the language used. and the station Is heard closing after a transmission from the CBS. Other reamers have heard HH3W and we would like a comprehensive report on It. Incidentally, after listening to Short Wave signals since Mr. Edel is reporting his first station in the hope that a card will result. Another good catch by Mr. Edel is ZNR, heard on 12,115kc. at?.30 am. Announcetnent at this tinte in English. A station has been heard In North Sydney by Mr. Brunt, giving a service in Portuguese and frequently mentioning Angola, English is also used from 5.30 am uni but noise prevents definite identlticatiun. It Is mure than likely that this is one nt the stations from Louanda Angola, Portuguese East Africa, but we have no knowledge of one on 9825kc. approx. Reports on this would lie welcome. Suggest readers listen for this from 5 am till 7 ant, when the transmission closes. "Ici Paris, Radio France." is the call heard on m. at 4.30 pm. Talks and popular numbers are heard and the signal 1s quite good. M Cushen hears this one at fine level. FBI', Radio Levant. now radiates a service for the troops at 1 am till 1.45 ant, and this station will verify. The address Is FBIJ. Forces Broadcasting Unit, Berult, Syria. A welcome return to e our c ranks is made by Mr. Churcher, ut Davenport, Tas, We have far too few reporters in that State. We hope that others will follow his lead, as Mr. Churcher Is soon to Join the RAAF. Good luck! Stations are heard well at his post, but there Is nothing In the log before us that Is unusual. The stations are there to be heard. SHORT-WAVE reports for the Feb. ruary issue should be posted to reach Mr. Ted Whiting no later than Saturday, January 6th, His address is 16 Louden St., Five Dock, N.S.W. Mr. D. G. Sanderson, using a two -valve receiver. Is getting line results using only 18 volts from an old B battery. Many stations are heard. Including XEWW. CFRX, and many of the BBC transmitters. Another received Is SUP2, which Is a weak signal tilt 4.30 sin. Leopoldville has been heard recently relaying several of the United Station services. The latest is the relay of WLWO on 11,6701m. at 6.15 am in the service to South Africa. News in French was heard ut 6,30 am and again returned to the relay at 6.45 am. Welcome news has been received that the long projected short-wave Voice of Australia Is soon to commence operations. The transmitter Is located in an area which should give the signal a good fillip, and we hope that, when the services commence, we will be in a position to give them lull publicity. We feel that an. Improvement in the matter SHORT WAVES TED i%(hhïing radiated will be welcomed overseas, and hope that the authorities will give this matter full consideration. FO8AA, Papeete, Is heard on Saturday afternoon by Mr. Fox, who Is stationed In the Pacifie Area. This one operates on 6080ke. and is a fair signal. The time here is 3 pm till 3.45 pin. Many times have we tried tor this station, but the noise here always seems to be too high. Listeners to the services of the BBC will find that the European schedule has been changed. Most of the transmitters are still In operation, but the times are different. In the main. na change is made in the Empire services: all times are given in the station list, when you can expect to hear these stations at their best. Miss Sanderson still does well from her post at Malvern, Vic. She has recently added a South American to her log in the reception of HO/13 on 9980ke. et 9.45 pm. It Is evident that this signal is heard better In the south, as it has nut yet reached good proportions here at this time; the noise Is too bad as yet. A One religious service is heard and it Is worthy of mention that this station is now on the air daily, whereas It was formerly silent un Monday. Apart from the Algiers. Brazzaville and Leopoldville stations, there Is plenty of scope for reception from Africa. From Laurenco Marques there are a number of stations. possibly- the best being CR7BE, 9870kc., which Is heard from 5 am and again in the afternoon at 1.30 pm, In some districts at least. There is another transmitter which Is heard In the early hours of the morning on Its frequency of 5880kc., and another heard at 7 am on m. From the Gold Coast there la ZOY heard on 00021m., while the South African stations are breaking through on the 49 metre band. The most prominent is ZRH on 0007kc. at 5.30 ant. Egypt is well represented by their services, which are well heard over SUZ, ke., SCV, kc., and SUX, 7865kc. The time fur these is 4 am and, on most days, a fair signal is evident. Tananarive goes well on 8182ke, at amend again at 2 ant. There Is another transmitter from Madagascar on 13,130kc. heard at good level at 1.30 am. 'This is one we would particularly like reports on, as we have no knowledge of their schedule, Kenya will be u fair signal on BINke. and M. at I am till much later, dependent on the district In which your post is located. CNR is a further one you can hear in the early hours on 8035kc. We would like to hear of anyone intercepting the same station on 13,985kc., which we believe Is on the air from 3 am. AU these Africans verify, and readers will be Interested In the response to your reports. (Further Notes on Next Page) I INTERSTATE RECEPTION CONDITIONS, NEW SOUTH WALES.-Early morning reception remains very good, with stations being heard front 5 am till 8 am. From then un conditions get gradually worse until, at 9 am. there is little to heur except the local stations and that provided the noise does not prove too much for the listener. AL about. 3 pm conditions improve quite rapidly, and good signals are to be heard un all bands in the afternoon and early evening. At night there Is much to be heard ut good level on all bands, and some very fine logs are being received each month on reception at this tinte. VIC'T'ORIA.-Reception in Victoria is similar to that In NSW, except that the stations as usual are heard till later in the forenoon than here. Several of our readers are hearing stations as late as ll atti, while at other times the conditions are much the same as ours. Night conditions are good and the higher frequency bands are in evidence. SOUTH AUSTRALIA.-Possibly more variety Is heard in this State titan anywhere else. but as the summer passes It will be found that conditions will even up a little. Cubans are still heard In the mornings and. apart front this, we find little difference. QUEENSLAND.-The Americans ate coming through well In Queensland, both In the morning and afternoon. Signals from South America are still heard In the night period and will Improve as time passes. Little outstanding has been mentioned this month, mainly owing to the lack: of reports. Early in the afternoon CE970 and TGWA are heard ai fair level. Indicating that the bands open earlier than here. TASMANIA.-Reception mach the same as In Victoria. Unfortunately. only one report from Tasmania this month, making It hard to judge. WESTERN AUSTRALIA.-Only one report front this State. but therein we find a good resume on reception over the 24 hours. Morning reception still Is good but, at night, all bands are available with good results. The higher frequencies are a feature and very fine logs can be made. Daylight reception is out and will remain su until the autumn. NEW ZEALAND.-In the absence of a detailed report. we suggest that reception will be still much the same us last month. Good reception is made at night with a smattering of stations which are not heard at good level here. RADIO AND HOBBIES FOR JANUARY, 1945 PAGE THIRTYFIVE

38 SSOr Lee rn4 le or our rraear en, loo. "«* er «rz'crrent'l Vou'r0:2' u -2 4Ct.. ova %her Inv riciner ce'd all ininivrin Tien tor ane neenl Annear. Inn %an *noon. I: n Wynn idler.2 v., en er9nris neon in , 010 rig co einer 0Per re erg...1=r fta ANY eloped. sr. roq.diss month list 9.141* lbs oddeentot of li. tddetioos...din is o., lins. Thil. il oil In oveliniw is " 'new! Iltotelere. re will.opoot I1e.1 55 SIb flot, 'Z'Sre do Ilbeee addesom.41. deader mein., M.. no eoenipl Ihn d This11 dides1 I.,. eiddress.1dieä urermefd2o. d `114:.= 27:4 nu or relernonese.... roosieälrlde.ny 7:er»Inn ninennint *re In sun, 1. found in Mete sags.. lo gingi.m.s..r tell:in 1,, Ia. io.0'272:11«.4%."re ,4;.:" "".15 P e5.123«..e0r00e1 men PACIFIC SERVICE 940Pr hen bey Mile Idtr= r1.0:. u.s.u0 une Muss.. Stu. OM e. Menke. orsnoll ine rt=2,r: onlic Oro niniverld NEW STATIONS AND VERIFICATIONS I lez :razz zejtettruier.7.«..:: wï =cm READERS' REPORTS non Orr on Pt Il ''''' Ovener. ern ern Inim COO: Ornälen min Min tonne, When a VL. via. In Lynn. :oniver- Won. inn 'LA boo W TI 41';' riein re in IV inn V.. roull, tn. On inn t'2"`iz4i.rg. neon or fn. orniz' 4 " 1.201re nirurginr: 72:ephr rrildterna.n.oeue Mt Pte.. - IPA«THIRT14IX

39 SHORT WAVES OVERSEAS S.W. STATIONS NOW AUDIBLE The list of stations shown below comprises not only those which have been actually heard in this country during the past few weeks, but those stations which should become audible during the next few weeks. A large majority should be heard on any sensitive receiver, and when a station is heard for the first time the readers' n ames who report it are shown in brackets. At the end of each group is a list of correspondents who have sent in reports of stations in that group. ENGLAND GUA-0050kc m. London. Good level In European service at from 4 pm. G ko m. London. Fine signal In afternoon in GO service from opening at 2 Pm. Schedule given daily. OSC--9580kc m. London. At 3 pm In European. and.in foreign services at other times. OED kc m. London. Best at 5 pm till midnight In 00 service. GSE ; 11,8g0kc m. London, Fair only in GO service am till 7 am. O8P-15,140kc m. London. Good nightly at from 8 pm, (}S kc m. London. Eastern service from 9 pin. Good one. OSH kc m. London. Fine signal from opening at 9.46 pm till 1,311 am. OS1-I6,260kc. 1966m. London. Good signal in African service 1.30 am till 7 em. Heard well to Europe in evening- GSJ-21,530kc m. London. No schedule is known, GSL-6110kc m. London. Good to Europe from 3 pm till 8 pm. OSN kc. 25,30m. London. In Pacific for NZ 3.45 pm -8 pm. fair here. Good In European 1.30 am ,180kc , London. Excellent from 9 pm in European service pm -mid= night In 00 service to Australia. GSP-15.31Okc, 19.80m. London, Another In European in evening at 8 pm and later. To Latin America at midnight. GSU-7260kc m. London. Used In NA service till close at m. Fair. GSV-17,130kc m. London. Good signal In 00 service from 5.30 pm till 1.15 am. 08W-7230kc m. London. In GO service In afternoon and Interferes with Frisco at night. ORB-6010kc m. London. Heard at good level at 4 pin In European: is on most of the night. ORC-28801m, 104.2m. London. Used in N. American service 11 am -2 pm. Reports? GRD-IS.450kc m. London. Only heard in European service at night. GRE-15,390kc m London Any reporta on this outlet? GRF-12,095kc m. London. Good signal On GO from 9 pm -midnight and often after. GRO-11,680kc m. London. Good In evening in GO service and in news at t am, GRR-9825kc in. London. Heard well In African service 4 am -7 am. and in close of N. American till 2.45 pm. GRI-9410kc m. London. Weak now hi Latin service in forenoon. ORJ-7320kc m. London Heard at 890 am In Arabic. only reports on this. ORK-7185kc m. London. Fair in Turkish at 3.15 pm, followed by Eurnpean transmission at varying level till midnight. ORM-7120kc m. London. Pacific service 3.45 pm till 6.30 pm. Good other times. GRN-6195kc 48.43m. London. European service station only, 1.30 pm till 6 um at intervals. ORO :c m. London. Good In home service at 4 pm. also in European. ORP-17,870kc m. London. Used in African service at 1.30 am. fair signal. GRQ-'.8.025kc m. London. Weak in Latin at 2 am. GRR-60704c m. London. Another in European service at from 4 pm. GRS-7065kc m. London. Listen for 00 service from 3.30 pm. Fair here. GRT-7150kc 4196m London. Fair in European service at intervals front 2 pm till 7.30 am. ORU-9450kc m. London. Weak in Latin in forenoon. In GO service to afternoon from 2 pot. Fair. ORV-12,040kc m. London. Good Pacific station 3.45 pm till 8 pm: best from 5 pm. Also In Eastern servits from 9 pm. ORW-6150kc m London. Another In GO service 2 pm till 3.30 pni. ORX-9690kc m. London. Heard well in Pacific from 3.45 pm till 8.30 pm. Also reported In GO service at midnight Fair. All times Eastern Standard Time GUY-9600ke m. London. Best in African service at 3.15 am till am. Also used In European service at 8 pm and midnight. GRZ kc, 13.86ns. London. Will possibly be in Use during the summer. OVO-18,080kc m. London. Heard closing in Persian at 6.45 pm; lair signal. GYP-I7,7001sc. 113,95m. London. A weak one at pm. OVR-21,875kc 13.84m London. Heard at ter- rine level at from 7 pm till pin In GO service. OVU-11,780ke m. London. Pair signal at 9 pm. 0VV kt m. London European service at 7.15 pm at fair level only. GVW-11,700kc. 35,64m. London. Weak outlet in African service at 1.30 am. OVX-I1,930kc, 25.15m. London. Used in er. American at 7.15 am, but is weak. To Australia ln GO at pm. OVZ-9640ke m. London. Fine Pacifie signal and again reported at I am GWA-8135kc 48.98m, London Fine signal in *Heroon at 4 pm. European service. OWB-9560kc m. London. Good signal in European service at 1 am and later GWC-15.07okc m. London. Weak signal In 00 service at 10 pm, GWD-15,420k in London Good signal at from 8.90 pm in Pacific service. later in Eastern service from 9 pm; good signal. GWE-15,435ke m. London. Heard at good level in some districts In GO service GWF-9490k m London. Heard through KRCA at 4 pm. This is in European service. GWO-15,060kc 1992m London This good animal in European service at 11 pm. OWR-11,800kt m. London. Rarely reported but in am.lce at i from s 5.30 npm tillaan 1.30 G%V1-7250kc m. London. Heard before HOER comes on the air OWJ-9530kc m. London. Good in pantile! with OWE et I am. UWK-6180kc, 48.66m. London. Best in European service at 7 am. OWL-7205kc. 41:64m. London A further European service station at 6 pm, also used at other times OWM-6090kc m. London. Listen for this outlet in the early ein; sometimes heard at 4 am. GWN-7280kc, 41.21m. London. May be still heard In Latin service ut till 1.45 pm In some districts (3W0-9825/10. at.heard]7m omn in Arabic service OWP-9900kc 31.06m. London. Heard at 8 pm at and tailing Europe at 11 pm. Good cutlet. e O nd Usedp emc till 3.45 alandon to 11 Australia In GO. OWR-15,300kt. 1961m. London. Good at 7 am in GO service. The following readers have renorted,stations In the above group: Miss Sanderson, Messrs. Gaden. Burke. O'Shea, Matthews. Kelleher, Edel. Cushen, Churcher, Sanderson. Lee. Hille. Jones. NORTH AMERICA LABOS-15,210kc m. Boston. Heard in WA 11 pm. Cannot hear here. WBOS-9570kc m. Boston. News read at 7 pm, closes with good signal at 7.30 am. WCBN kc m. New York. Relayed by WCBN U1,145kc.t till closing at 7.15 am. Fair level. WCBN ,x m. New York. Relays above service. WCBN-9490kc m. New York. Closes nt 5.30 pot. Interferes with KRCA. WCBX kc m. New York. In transmission to S. America front 7 pot, reported from WA and Vic. WCDA-6060kc m. New York. Used in "Hit Parade" programme 3.30 pm. Reported from Victoria. WCRC kc m. New York. French at 7 am. Spanish later, fair signal. Logged at 11 pm, also fair, WCRC-9590kc, 31.30ní. New York. Opens to Europe at 6 pm. News at 7 pm. Good signal. -W0EA-9550kc m. New York. Good from 6 pm. reaches good proportions by 9. pm. News 6 pm and 7 pm. WGEA-7000kc. 42,86m. New York. Heard closing weakly at 5 pin. Never much good un this frequency here. WGEA--6190kc m. New York. Closes at good level In European trunsmieslmi. WOEO kc m. New York. Another heard in WA and Victoria at 10 pm. News II pm. Cannot hear locally. WGEX-11,a47kc m. New York. News in English at 8 pm and 10 pm. Good one. WGEX-9SS0kc ,. New York. Quite a fair signal at 7 am to Europe. WKRD-12,967kc New York. Good signal through noise at pm. WKRX-9897kc m. New York, Scheduled 8 aí am. News in English fair et 8 am. Fades here by 9 gin, WLWK-15,250kc m. New York. Fair here till closing at 7.15 sin. Heard ln WA at pm. WLWK-11,710kc ní. New York. Fair signal al 9 pm. News read at 8.30 pm. WLW1., k ní. New York. Another heard in WA at um with good signal. WLWtr2-15,200kc New York. This outlet Is on at the same time. Cannot hear either. WLWL-9897kc New York. Opens at 9.15 am. Heard most posts. WLWO-11,710kc m. Cincinnati. Pixie signal closing at 7.15 ant today. Good service. WLWO-95110kc m. Cincinnati. Heard ac fair level here at 9 am. WLWO-7575kc m. Cincinnati. Heard well In transmission at 5 pm till 6.30 pm. With WLWA and WNRB. WLWO-6080kc m, Cincinnati. Listen for it at 5 pm, good signal. WLWR kc m, Cincinnati. News In English at 7 am. closes at 9 am: reopens at 8 pm till close at 9.15 pm. Fair throukhout. WLWK-12,960kc m. Cincinnati. Heard 7 am in news, closes 9 am. Again good 8 pm pm. and calls Italy at pm. WLWK-9897kc. 30,31m. Cincinnati. Fair at 9.15 am and from 8,15 pun pm. VTLWR-7826kc m. Cincinnati. Heard in latter transmission on 9897kc. WLWR-63801(c m. Cincinnati. Closes good signal to resume at 5.15 pm, with relays on 78251(e. and 9897kc. WNBI-15.1bekc, New York. Heard weakly une night at midnight. Good level in oilier Slates. W'NBI-a870k6, 31.OSni. New York. Fair signal at 6 pm. Remains on till 8.30 pm. WNRA-9850kc m. New York am - 9 am, closes fair. Reopens at 5.15 pm, w wn own tip hour, tuna T(WTY Inr..,..r...- WNRA-6100kc m, New York. Closes at 5 pm, good level. Relays WNRX and WNRI. WNRI kc m. New York. Good signal from 7.45 am In company of WNRA, 9850kc. Schedule is 8 pm till 9.15 am. WNRI-13,0701íc m. New York. Closes at 9 am. fair only. Heard well at 10 pin. News ut this time. WNRI-9855kc m. New York, Heard at each end of transntlssiu from 9.15 um till 5 pm. Fair at night. WNRX-15,550kc ní, New York. Closes at 8.30 am with fuir signal. Relays WNRI on 13,050kc. WNRX-7565kc m. New York. Operates 9 pot till 5 pm. Poor on closing. WOOG-15,190kc m. New York. Poor now is report from Dr. Gaden. News at 11 pm for those who can hear It. WOOC-9650kc m. New York. Opens at 7.15 am with fine signal, good in some posts ut 11 am. WOOC--6120kc m, New York. Closes at good strength at 6.30 plis. Best at 5 pm. Relays WOOW on 7820kc. WOOW-11,870kc m. New York. Another V of A at 7.15 sin., pot In,Q. RADIO AND HOBBIES FOR JANUARY, 1945 PAGE THIRTY-SEVEN

40 A.0 IS M." 10 Wm Oaemiu n rze.inxr urre w..." **.".".."" '74; aaa Wow., Neon 4nrsuen W.W.I nine 11: 30.00I00Ui0: A. O. MOH ow moo..ana v2.23:1'avaowo b! O. Ian. PM Km. la non V ,20 ät nOt-11431: Vai '41m. WM POW wire eg 3[ :',/:"4.02:::111 vati-ligl. 41 I. WIN0 ma 0ma VIN.1)!TrOlIf II Um Own :1. >1= Wen vt u. WU.. Me» 141 I Pk V1111Ce4C "Onlooln. w. Osun Mpg% "Vat.. be' nr rwens Own SOUTH AMERICA :21:,:i_.;f3t2AUS"7, AUSTRALIA & OCEANIA et2211ms '13Z aarlaola.7.:.2 L., oaa. ogräz AFRICA - Cairo m Pun Puna.* Own J P: C. Vernnen P no aw Claw al w 3 Sao 21,42Zir< ry "licej! grkotrain / 4nowou ,em O.. ZVI... oa on We Abu en at nu CIlla...-.0V102e 1111.; T.:nary Sarauea -- WItA1341:4170r 31334n. Lan Irensut UNen 211;,4'.1% *"' 'f-,.ti:1-1.7, k:0'.r... Seuxion oom PEI u' lb lini 311( 3<;;j1to.U.'.:. non Fur wn O. 11."4111%141' '2.1.11n1Z `;:n euellar.t. latiultte'/..rear'ti. m NOW pm unn nu. 101:r =1:14:. anwünenn " v.-% -.?.f.0 r.. : t' r 01 rr s2 r » I.7.111". e rr"..i gar ! o 454:U:;1/414' ';'7U'll111 r111=413414z z Iwo Fr owiner Oew 134'11/ mnInn WWI.. Cow K WY Vor P..nowu Winn «am moan. 1V,:a:nlo":2".313. cantil7goo.0t00 va.a. ead haul an Met IPIIRRYRGPII RADIO AND HOMES FOR JANUARY, MI

41 uhorne, sr THIS MONTH'S RECORDINGS This month we give the contents of three popular release supplements. Included in the list are two special Columbia discs by Marjorie Lawrence, and three featuring George Trovare and his concert orch "Audisc" also commente on three recordings made by the ABC National Military Band, and listed last month. [blet. by ern the seaantlnu Bro.arns[Ine commleslrn i. Blues IV 10. x.: OLLt+n O.Iremnnr a (Contlnned on Page RECORD REVIEW PLASTICS AT SEA ANEW Instrument which slmplihee taking bearings at sea, day of eight, Is made of tire transparent rsst arryllc resin Plexiglas, a prodnet of (Rotin, & liras e no., Inc., Philadelphia, Pa. The nalument weighs Ilb., Will nest in water, and consists of a terreatafal globe surrounded by a ralatlal sphere on which hr25 stars useful in navi - positionna. Luminescent gatlon teriskamake it visible at 25 feet by niant, and the instrument has arcs and rings which eenp It for use as a sextant. In daytime. The Invention of E' H. Hagner, of San Antonio, Texas, the navigation instrument was designed especially for use liferafts: ut us also employed in the teaching of celestial navigation methods. The INSULATED RESISTOR Popular Releases COLUMBIA rom bne anaev 2.tuet voeux 1. aw < Mn erse d. pick h nies o.rh of Type BT end Type BW Insulated Relis lors une* I.Fen IRO Bred andd Induced taled c construction n th. rml.nrce Geld au the sale of ms al un. the fi.r1 ye. et sires piauler ls than.reds the.prdrty al th. /rend ro..rds the u, of rnsu lotes r satan Based r eslenl Sales a rfe larges, m mas* hng buy n /he rad. and eleahrael rndusrrm d p..d lee and a n the ablle of chu mader and xclusvely IRC r tance n development le mbrne economy.r1f dependability IRC B/1010 AND NOPPIES FOX JANUAR. IyN PAGE TNIRTI.NlNI

42 sowes Isom the CONS TRUCTION WORKING MODEL Of AN ANTI-TANK GUN solder a piece ofit din plate Li axle, he first four tl hula This mini niature spring -loaded gun, although not an exact scale for the screws revs ay which it is al aashrs model, makes an attractive toy for the young fellow. The gun lo See b osoidered rto giilo finial] washers to will fire a light wooden projectile for a distance of between ihr wheels run true', the wh els are thirty and forty feet, according to the strength of the spring used. (teed it position and a washer soldered an to keep them in Place. LOADING is aecomplished by i w After say roue - with a file and sd anpap. wemle the herring a suitable piece of wire down the muzzle and pushing back the plunger' until it engages on the By T. E. trigger. The barrel is made of two pieces of hollow metal curtain which'ean`be or similar, scraps tuit Le Sueur bought cheaply at most hardware Pro - re a gastores. a bore oaece f t tonichen Inch. and 1Thisa will [ the spring to the end of the form the main barrel. breech and cover this poetloo of the On the muzzle end a metal collar plate tin Is soldered n e W form a slight will effectively hide teps and enlargement about t Inch thick. This trigger mechanism. no actual purpose íe the work- Do not tor get to cut a small hole Ins ing the gun but improves its appear- the end plate to allow the trigger to project. The placing of the parts and the model will only require s The breech Is a second pi of tube c and r measure- fixing then to be painted. Use up your scraps slightly larger than the barrel which ment en adjustment Of paint priming mat It is slipped over and then soldered to it. Cger Compress the sprng in the barrel oft b yneatlythe camouflaging ni dun green g grin Any slackness c n be taken up by and measure the distance inside from and brawn caters. forcing in small pieces of tin plate the muzzle the e plunger. Whilst welting for the paint to dry, /cut from a Jam tint before soldering. T ensfert this distanceto d f thc b outside of obtain a piece of eightten or gauge The barrel mount Is made from a the barrel and bore a hole, say, of inch wire, about 10 inches Mug, bend e piece of tin plae or galvanised iron diameter, which should be large enough end to form a handle and this will do cut to shape, bent around the breech to Lake the catch end of the trigger. to use for a loading rod. and then soldered. The shield is simply a rectangular piece of tin shaped nd then fitted over the barrel. Before making these tuo parts, it is advis- RIVETS OF METALPLATED PLASTIC able to make a paper template. Any errorsin shape or sire may then be RIVETS of the acre lies, cellulose the Douglas El Segundo plant. They rectified without wasting material. acetate butyrate, ethyl cellulose are designed nub a hole running from For the spring mechanism, obtain and fairly Strong spring and cut it other svnlhetics, used by the the so head that, almost to the bottom oi the when compressed, it will be about two Douglas Aircraft Company to fasten rivet. Compressed air is forced auto niches long. The spring must fit into fabric to aluminium ribs, have recent- the hale after the rivet, prevleualy the barrel and allow free movement. ly been plated with various metals. softened n oven, is t ed am. rr Th is inch mild It has been found that tingg plating tlu e gives [ vt steel, brass or similar, some et Inch long and having a shoulder filed on one end IL Is to thla that the 1mal end of the spring is attached, after making [tain that the plunger moves freelyy In the barrel, AI. he the ear end the plaatlm rivets greater tensile strength, Cexural strength, and dimensional stnb111ty. The a plated Avers were developed by S. lb PblBlpa, Raeens ecegloeee at The trigger is o piece o sl ut wire bent to the shape shown in the diagram with e. small tube to form the pivot at the centre. The pin g right through` and le soldered i the n barrel housing. In order to keep th trigger always in the "on" pasha n II return spring is added shown. Before trig er place tsoldering Any e i au s erg é then be g c r ea with Mlle le trouble. When all of the working parts are acting sni UM, solder the trigger in Mae, The carriage Is mode Ir m a y Debt nod of about t. inch thi kness. Two Moms are required and m ke hem to the Bie and shape e 1 r ni k toll, elareumhtees net wl. wheel.the inch i wo d. law the sow al d up theo'roughhplacesaiwi hie The mritc of desired. axle is ial formed 'fromtl le. i Inch rod es heavy gauge v ot f it le bent to Che shape a iici appo It %HIsue the guna a will enh strong v will be eded to Bet a"spume corners when ben Inge the htoedsmetnpnmn uii patewer ef oetlte scprasiob[e fo plastics to metals. Moe there V no danger corrosion and Meet/tie ealn from Masks rivets PAGE FORTY RADIO AND HOBBIES FOR JANUARY, left

43 It! Aeeb SYNCHRONOUS CLOCK (Continued from Page 101 one shown in the photo was made trom.veneered At this ntagep s the writer would like to point out that he Is not an authority Mn alarm clocks, and that every alarm oak does not necessarily have a 40 - tooth wheel on the second hand spindle. Ones alarm clock, which the writer has had a 35 -tooth wheel on this spindle. A little thought will show that such a wheel ill need -Loath pinion to mesh with it to obtain the 'necessary 5 to 1 reduction. Other clocks must be treated on their merits, and leave plenty of scope Ior the exercise of ingenuity, which, after all, is the thing "hobbyists" get the greatest "kick" from. If you find a little difficulty in getting the eight -tooth wheel, do not In it (Rat you brass roxitelyy one fifth of the diameter pof the wheel, h divider cut slots with lt chacksaw ulat each division, and the to the shape of teeth. It is surprising what will run at this slow speed, and f you are careful yon need not be disgraced by the pinion you Make, The clock will run equally well In both directions.. if find you tine running. way from yo lust a its âirecfi on! If you followed the instructions carefully, you have lost one more excuse for being late to work. RECORDINGS (continued from Page am WORKSHOP HINTS FUR THE ' HOME HANDYMAN / / `PAR:E4 Ikr By W. G. NICHOLLS RURREE HOSE HANDY HANDLE by nlolling a flre Inch length el rubber host or pan Parmi dipped one., the binding Ihnne of er.i Mown Welch snilntli r I l' i SPRING STEEL. STRIP RUBBER SCREW PAD enon MEAT PRESSER When praying meet oodac < Ih amerm ould F length of :dam the ttttt th dinc In place and Me wring keep ol Mere Te ERIC WIN8TONE and RAND: ócn ''Innere's esaroenoaa gle;roj,1 Blum -EN. Ren, 5A 171r2".nyfaIvc.,".ng;iee u,e2.2 d one e: ^ ó r :,a d.mecca FELT STRIP NAIR BROOM HINT ^yam BROOM ssln,hair beore ICI l IÌ I GARDENING GLOVES TIPPED WITH RUBBER 2,",""'" ed te,..an fumbrafbell, in,o aov a.kinote,..., is worm Platine Por, REGALWONOMOME 1"`,U.''''"`"" ALEX wakana' agr Men, 71gN e a. wdn.rrbt alt <a.t wart r41, OTIS and ELEANOR, Vocal with Mande= any LGDER ans ORCIL:..The %R oagr "' VrjerVeck HAND PROTECTOR home n old parr el eargenlno r M1eu.ii i' 9 ul of olerr PAPER. DIPPED IN FAT lilt. POT CLEANING HINTS ebeltomee whw, they become * moved ledhout cnc spin :27; RADIO AND HOBBIES FOR JANUARY, 1945 PAGE FORTY-ONE

44 ofes POPULAR SCIENCE JOE'S COLUMN' - HOW STEEL BALLS ARE MADE WE here often beard Mel on is the lifeblood of modern wer. Other items too, have important parts fo play o saheb e,or. Just think would heppen too most of our precision.chine; of betne end production if by some unhappy m acts these bearings a destroyed end replace. s prevented. In a hurt time noihru end delicately setae red echl,p....id soon c me fo grind - Yes, if c n b. s eted with cerstop. tainty that modern war rolls.long on bells of steel. Actually, bell bearings have only been in uce since the beginning of the century. A m.. improvement o Me ball beerncs a the roller bearing which, although it does not run freely a the bell bearing. eennend much greeter loud. end is...fora much favored for heavy machinery. A still further imp.meat n the roller bearing is the sphericel o roller. Shaped aarnewhet like a little barrel, it het M. s nn,ng gueflie of the ball a well a the load -carrying the roller. No of details on the spherical roller a available yet-ilse; much till being o the se et title r, considers NI. a is knowne,,,, about the,oak. ing of perfect ball for ball bearing. If Me bell is fo be under ono Inch in diameter, piece ci steel is coldpressed ugh sphere, slightly info lrger in diemel than whet the fin- a. ished bell is to be. This piece.alone with many other s through series of grindings between grinding swheels ei gh 4i,re. ally end turning i. opposite directions. As they ere always rolling end changing their Ns a1 rotelion.11 the balls steely. The a m t,..tmenf end ere ground evenly. Then the bells era fumbled together with send in e revolving conleiner like Then sc e s al glad. leather... subsfituled for th. send end the bell, a..in umbl.d until m: finish results. Even char.11 this machining, the complete number of beta the on. she ere graded still further es difference of a tenth of a thosendlh of an inch e few bells. bearing would have echoers. effect on its running. Al one place this country where e large r amount 01 bell bearings ere reclaimed end put into..rein, I have s en of thesegraders n It was designed bye ihd sier. n group of workers. Basically, ir can le of two round steel bars about one inch in diem.ler end about twelve aches long, machined to. n even finish without e y fole,.nc.. By means of fin. thread a end the bee a with e. ben lbem keyingre e mell. leper, set' few thousandths v of as nch more then 5/16 inch of o end end a fee thousandths of en inch less then 5/16 1.1, et 1h. other and. A 5/l6 inch bell is rolled along end painter is set just where it fells through. Then other 5/16 101, balls ere rolled slang and all those 11,..1 fell through a; the painter r p back into the one bearing, a This is another ell exempla of the ingenuity of workers. the end doing splendid lob demandned by werem.'conditions. PLASTIC `SAND' CLEANS PISTONS The US Army Air Forces and same of the commercial airlines are sing plastic pellets in sa ndblasting equipment to remove carbon from piston walls and the narrow piston -ring grooves. THP: operation was at one lime given a polish without abrasion of the accomplished in three 'reps: metal i and wlihout pnleerls'mg the inorsion of the piston a chemical pellets, It is reported. The spent pal- le In s; flan the carbon; owning e. rs tall Into honor and are mated. e pfs1on on 0 lalhe: and manual c One charge of T` une pelleta may be outlook' of carbon from rim( grooves. used edec[ively in he sandblasting i Blasting with the use l of.lover seed for bort three da, the or cracked grains proved faster and which endt cheaper; but short dopey and short se -life of the graines led to the development for ren. time they 1ILLLLee of enough greasy carbon to o necessitate recharging the ante. the ear'bonof ópeteì ohelle[a The pelleta are of the cellulose acetate Tente I, especially prepared by Tennessee Eastman Corp., Kingsport, Tenn., In granular form, 1/I8 -inch in size, with n intermixture of smaller sizes for re- moving oing carbon from ring grooves. charge of 50 or 80 p0uncls of granulated pellets is placed in the andblasting unit, where the pelleta are against the piston sides and ring groovfaro es, knocking, theis cflrbmteneou e The ly SOAP BUBBLE PLASTIC Blown like a soap bubble with "ah' - forming' technique, single sheets of e transparent plastic are shaped into nopies for fighter planes. The Plexiglas. "bubble," used on the Thunderbolt P -4T. enables the pilot to see in all directions, end also reduces weight and wind resistance. The process by which the Plexlglaae is actually blown to shape eliminates struts and frames, ovals were used m earlier cuwpkea BOOBS FOR MODEL PLANE FANS "THE MODE. AEROPLANE MAN, UAL" ;Third Edition,. by L. H. Sparey cival Ms1.11 As Co Published ÌÌa d cloth rover. age 231 pages. Australian price 12s8 plus red postage. Mode/ aaa eroplane has sbllshed Itself one 1 theinter r hobbies of the rising generation. While a few are content to follow published plans, there re plenty of ai thusloate who ant to know the ',shy and wherefore, of each model they build. end.in many cas, to evolve their own designs. "The Model Aeroplane Manual" etrould exactly meet the regnirernenfe of such folk. t. problems fundamentals theaircraft of Hight and then proceeds lo deal separately and in detail with each major portion of a model. Constructional hints and m thada are mfreely withthe text tratediven w pho graphg 11lus- and drawings. There is a special chapter on gliders, at the end of the book, hull sd, tructions In- and plans are given No fear high-performance models. A book we can thoroughly recommend d for enthusiasts In fl ying mo del aiimircraft. /Review' copy from Angus and Robertson, Ltd., Castlereagh - street, Sydney./ `THE DESIGN AND CONSTRUC- TICl0 OF FLYING, MODEL AIR- CRAFT," by D. A. Russel 'Produced by Aircraft Technical Publication, Ltd., roc Drysdale Press, Leicester. Hard cloth. 248 pages. Australian pdee 17,6...oz.), postage 81. This book would make a excellent follow-up to the "Modem Aeroplane Manual" just reviewed, its approaeh the hobby being on a generally more ambitious plane. Thus, the preliminary chapters on the Imoaceory of hot t ccould be rn egarded as a ourse n. he r ot to about the various types sof ding alrfofl tor' both monoplanes and biplanes. Control urfaces, air T,": ecelve the thorough treatment, efltdrag find there ogledare chaptela drag and performs c these latter with special reference to models. Rubber and petrol motors receive wton, also do methods wind- datfl tunnels, design i embodied r- seven appendices and inthe farspacedthroughout the text. rest mg wealth e book is la illustratedwithwith hue drawings end its'o with podeo- Thehs aumoeris ot obviouslvflymoosstmtaken with the larger and more expensive ti es of model, one shown having a wingspan o lees than 10 feet, arai riven by t an onoeytinder two-stroke umto, An excellent book for those who wish to take up nodal Dying on an advanced basis. lour copy from Angus and Robertson, Ltd.. Castlereagh-stret, Sydney.) (please note that books reviewed /Mope nd or Page Si 0f this ism' or not distributed for sale by "Radio &Hobbies.` Inquiries should be addressedor other of the booksellers adve,ir1d11aa m our t'oiunim.) PAGE FORTY-TWO RADIO AND HOBBIES FOR JANUARY, I94h

45 ANSWERS ANSWERS TO I:ORRESPONDENTS UNDER TIIE PERSONAL SUPERVISION OF THE TECHNICAL EDITOR.r..br.e I.n ::21. IÌ.e f E.«." é barpivl.y 'llrâb r.u NWw' Tlaebw',r w nrìw ún.. oâl Óruawr. 1Nt W Il n itw1w..i N Flúrlu I 1Y4. IYk.r < wmw l'vn mâ%.:'n.:t,',". Lei Pe. M4 rvmt<im Iw i lum. m«iimiiu.r.lro n. úrnrra. ::I Irmvr ú Ai w N mulmu a irm.ww.. NA BO :ry" r. NM nw n"0rtrrnwa «rs...w<""..n ue n.wrl up rvq T,ÌI IY Im'ttlat. rl"menut Mi âl Ìu IrrÌ«r lm MrN rwip<n ÌMb IN.«, w, n.01.. eon b:- n «rroalun1 Ir r <M. rlm w.- 'DJn ur...,i m la J1.1e. Ì q.m"rf n Miu w N. r wlr.rll Ç M" ntl Aaa :n; lur.in < nry nr. en n 01 Mn..I M NW únome Lwe lnam 'JM rgmìrwm. NeY I+âïw.: :«Ó. IN min M".:Y««u.ull wu. ""'" 9 ur m.imi 81. r, M tlrrl<a ronnaa..w e..inp â :ël: Ir n'âlia wms a rdr i107.3 r ' ".. ' m.. nr ro" lis: emw eat I..m Inr I A.<i.rb r....rp.w... IAa:,x.mO- u`.nl.oe..p. RELIEVE IT OR NOT w. MA..r Ho WY 01.N10Ne mrw.i.he., Eg. ErNANA SIENNA/AS IM'bro.l Pty. ltd. n «.Mro.r., o.ww.w TIOlITSO m :é â:,m<im: c>m..m:. b ad N w. rbml..lt CI.I'n w towed. II 8ÌfOC6 OUT BLOWS eau r INN..M.war. É6 TALL. s6 ste060 IfMpb LrerO.Mllw.wMbWNua w66stl550. l.l.uwl, bl..m nr m L ti, idn aa.d, D.IN. NY.I. N11 wemm.e.q sn, la IRA be o... RADIO AND HONISS FOR JANUARY. INN.033. malted" er" a Not" Re' IIia.Mr :..m Ì r: I:.n2::...1 r..:"w â+.i»::ÿ < ' number..`n.n'; t. "<4a:urabw pu tt.. ur Cw 'rmi tertumi Y.mbb t. Nram. RADIO DEALERS AND SERVICEMEN WE SPECIALISE IN RADIO PARTS CARRY C A LARGE STOCKS. Oriole to our cesdi- Nato sane lines we V uiamble, but re rill do ow utmost to Imply your require meats. Our prices we Me lowest of/snug sad re supply only quality goods: DAVIS RADIO CO. D'hr.r.l. N...i;., < H..u. el.«t. sn..r. N.n.., Saw... PHONE PAGE FONTI -THERE

46 ANSWERS L. Edel (EdgecllR. NSW): Many thanks for your letter and reports which are of so much Use to us. Hupe to meet une day. Regards. B. Kelleher (Newport. Vie.): Good listening again this month. We hope that conditions keep up for you, Much the same here. P. W. Brunt (North Sydney. NSW): You will see continent on the new station you are hearing. Think wo have a line on thin one. Good (uck. A. T. L'ushen (Invercargill, NZ): Flue log this month. Will write to you soon. R. M. Chureher (Deroupurt, Tas.): We had given you up for lost and hope that in the future we will hear from you more regularly. Regards. D. G. Sanderson (Torwood. Q): Pleased to hear from you, your log Is a good one, and hope there are more to come. A. Lee (bterewether, NSW): The receivers seem to be doing well now. hope the aerial will come Up to expectations. Regards. G. Kelly (Shorneliffe, Q1: We have heard of you. as you expect. Hope to hear from you soon with news on the SW stations. F. R. Shannon lmeringandao. W: Glad to hear from you, and hope this is only the first report. We remember the call you had W the good days. It won't be long now: 3. F. Fox (New Zealand): Your reception seems to be as good as here: thanks for all the dope. R. Matthews (Riverdale, WA): You seem to be doing well In the contest: elll be glad to hear the result. How about some letters from your colleagues? C. Maher (Gladesville, NSW): Thanks fur the details but. on tins occasion. we had them. Keep it up. A. C. Wise (Lower Moutere, NZ): Thanks for the kind remarks, and hope to get monthly reports from you. If we call help, let us know. Good luck. D. V. Mlle (Kogarah. NSW): Hope that the set Is better now. Will expect some bumper logr next month. A. Smith (Ashdeld, NSW): Good luck In the examinations, Will ring you soon. M. O'Shea (Bellevue Hill, NSW): Suggest you Lry to receive some of the weaker stations that are on the bands you listen to. K. E. Jones (Forbes, NSW': Will supply the addresses you need. Your letter too late for last month. Regards. bliss D. Sanderson (Malvern, Vie.): Another good lug tilts month. Good luck on the - verification. K. B. Gaden (Killarney. Q): Thanks for the nice remarks re the book. Hope you get a little Line over the holiday, as reception should be good. Regards. WANTED TO BUY, SELL OR EXCHANGE Readers wishing to buy, sell or exchange goods are invited to insert an advertisement in this column. The cost it 9d. per line; minimum charge 2/3. Advertisements for next issue must reach our office on Saturday, Jan. 13, U'ANTED-2 or 3 Ging H Condensers. DA9 Dial. 5,9 Rola Speaker. 12,000 ohm:: Give prices required. E. Botehkin. Nunnup, W.A. \I,'ATNrTED -lxnekrmc ekaa ershli letec imth nad euldeidt, tecoumdp..w. Lowe, (toad, Pori Adelaide Issue "R. & H." 11rANTED-January, 30155, L.A.C. Hovey. 1.. 'l'., e/o 33 Richardson Street. Boulder. Western Australia. N ANTED---Gas Tetrude Tube of the 2050 or Type. C. Arnold, 23rd Heavy A/A Battery, A.1.F. - ur R.C.S. DiW Kit (Aerial. I`17ANTED-Crown R.F.. Ose. and Switch. matched to 3 -gang "H" Condenser or separately. F. Phillips. Box 202. Rockhampton. Queensland. WAY= --t 3 Gang "H" Type Condenser. Electric Gramm Motor and Pickup (Crystal for uret i. Must be In perfect order. Write stating price. G. Julies, Box 3u, St. Kilda P.O.. Vic. "ANTED-Coptes of "Radio and Hobbles" for August. November. 1942; August, September. 1943; February, August Must be in good condition. Phone F31526(1. Sydney. '%. ANTED URGENTLY-Copies of "Radio and Hobbles;' Feb. to April Apply. state la," Creek, South Gippaland. Victoria. (5\.r ANTED To Buy-Books. "Modern Mechanics "' Flying Manual," 1929, 1930, 1933; Flying and Glider Manual : "Popular Av a- tion." with plans tor converuug vac o'.. engines for light plane use. G. Jamieson, BeWlingra, Bredbo, N.S.W. APOLOGY: To readers who replied to my Advertisement in November "Radio and Hobbles." There was an error at the post office and no mail was received by me. All goods available. G. F. Hillier, Box 13, Edgecliff, N.S.W. Q&LL-New 5 -inch Magnovox Permag. Speaker. A7 25/ vol. Electric Fun. Otter? C. E. Neilsen, Dungowran, Nikenbah. Pialba Line. Qld. FCCHANGE - One old -type Typewriter for Y home recording outfit, or Camera, or Tele- 7:oope. C. Fieidhouse.. 19.Brunte Rd.. Waverley. T,iXCHANGE: "E" Type 3 -gang Condenser for.j 325v. x 325v. 40 ma. Power Transformer: Good 6G80 for good 80 or 5Y30. Airmail. Cpl. Penberthy, Group 481, RAAF, Darwin. IN good condition. R. & H., Vol : 1 Vol : Vol E. K. Buseh, 113 Carlingtord Road. Epping, N.S.W. FOR SALE: Complete Set of Applied Electri- city Edition, III volumes, cost I. I7i 17/-. Sell 10. A. Hughes, lu City -road, City. OR SALE-One Solid Model, ''Jiin, built nia 1, scale and camouflaged "Spitfire' Plane, a good toy. 1. W. C. Campbell, "Glenayle," Hivesvllle, Queensland. SALE-Valves, Mica and Tubular Con- I'iOR densers, 1 -watt Resistors, and other lines ayullable, Postage extra. No C.O.D. R. N. Tusworth, e/o Peat OB10e, Sarnia, Queensland. `ELL R. & H. Hi -fidelity Nine Receiver Magic Eye. Separate power chassis. I2PO4 Speaker. All parts. Used a month. Genuine reason selling. Offers? A. Dabeletein, Laldley. Q. rig() Small Electric Fana. any condition. Vol. A- IX and X to June. 1945, of Newnes Practical Mechanics. W. H. Stevens, 141 Helmick Street, Merewetber, N.S.W. SALE: 18 Months Complete Coptes each 141OH "Radiocrafl" and "Radio News," U.S.A. Publications. A. W. Mark (BWI1144), IS Arbltration-st., Sydney. 'ELL: Radio & Hobbles, Jan.. '41, to Nov., '44, t- plus 9 collies '40, also Radio World. Dec., '40, to Feb.. 43, and April. '43. to Oct., '44. Complete A.R.C. Radio Course. Ohirardl's Modern Radio Servicing. all as new. What offers? T. Orr. 233 Wellington Road, East Brisbane, Queensland. SALE: 9V, S.W. Communication Receiver. FOR I R.F. Stage, 2 I.F. Stages. Noise Silencer, Magic Eye, A.V.C. Independent Audio. R.F. Gann Controls. Fitted In Black Steel Table Cabinet with Chrome Fittings. M, Carter, 242 Albert Road, South Melbourne, FOR SALE-Genemotor 1 p. 12 v. 0.5'. mu V. at 50 MA, very good order. 7. Freight free. "Efco" Dual -wave Dial. size approx. loin. x gin., for H Gang, new, 32/- post tree. "R.C.$." D.W. Coll Kit. "F" Gang. no R.F. Stage, new. 27/6 post tree. V. J. Yalden, Cedar -Party. Via Wingham. I41OR SALE-Everything New Cur Radio. Antenna. Crystal and Carbon Mikes, Crystal Pickups. Spring Gram Motor, 121n. Elec.-Mug. Speakers. R. tit H w. Amplifier. 3 Spkrs. Details gladly. Vibrapack 6 -volt input volt 150MA output. Coil, Kits und Gangs. Hurd - to -get Valves, Transformers. J. W. Golding, Donald. Victoria. 71XCHANGE-Octago A.C. Elec. Fan v.,.I S0f60cy.: Sllovac Universal Sew. Machine Motor. 240v.. 75w. qty. New Swing Records for 3 or 4 v. amplifier. Or sell for best offer. R. Brown, 0 McIntosh Street, Mascot, N.S.W. (OR SALE: "Delco Remy" generator In good order, 6V, 15A. complete with cutout amp. meter, 4.15'-, freight free. "Hand!" pump - less petrol Iron. hardly used and In perfect order , freight free. Small model sail- ing boat, metal hull. sails well, good order, 1, 'post tree. V. J. Yalden, Cedar Party, via Wingham. I ANSWERS TO CORRESPONDENTS (Continued from Previous Page; (Runtville, NSW) Is anxious to obtain a copy of "Radio and Hobbles" detailing the construction of a 4 -valve portable receiver. A.: Portable seis were described In "Radio and Hubbies" for December and Chrlshnas, June. 1939, and November and Christmas The "Portable Tlnte" of November, or the "1911 Portable" of Christmas, "1940, would probably be nearest to yolir requirements. None of these Issues remain in stock, but you may he able to obtain them by advertising In our "Wanted to Buy - columns. Alternatively, we eau supply the circuits through our shilling query service. For your information, we would point out that the construction of such sets with nee. parts Is prohibited at present and, In any case, you would have no chance of obtaining the necessary portable -type butteries. LAC B. (RAMP, Darwin) has apparently gained much help from the "Sound ou Filin" Series, and suggests that we should go ou to describe precticnl Installations and the conversion of silent 18 and 95 in llianuneter projectors for sound. A.; Many thanks for your letter, and glad to note that you have enjoyed the particular series of articles. We may possibly publish something In the way of a simple talkie amplifier circuit at a later dine, but have no Immediate plans to tackle tile other aspect as well. The conversion of silent projectors for sound is by no means a simple job, and the method or attack varies with each Individual type of projector. There are various books on the general subject of sound on film, but we have never Conne across one dealing with the particular aspect in which you are Interested, "Small Set Fan" (Dimhoola, Vie.) enters a plea for a description of more small receivers (one to three valves,, larger sets being beyond the financial resources of many renders. A.: Many thanks [or your suggestion, but we would point out that we have described Many small sets during past years, copies of which are still available through our siding query service. In view of the present lack of new parts and components, there would be little point in virtually reprinting often described circuits when (here Is so touch other material on hand. Nevertheless, we do hope to give one or two special features for small set fails in the coning year. W.MeK. idtmwleh, Qld.) mentions that he has built several of our small sets. but has been post Impressed by the performance of tout described In September, using a 19 and 11)4 valve. 'A,: Many thanks for your letter, and glad to note that previous correspondence through our shilling query service proved helpful. R.I. (Vaucluse. NSW) points out an error its a recent article by Calvin Walters In which reference Is made to laughing gas, A.: We must plead guilty, for you are quite correct. R.J. When we showed the article to Calvin Walters he Just exclaimed: "How the heck did that happen?" Well, it did. and see didn't (notice it, elther.,other readers have mentioned thin oversight. but the letter from R.J., of Vaucluse. was the first to hand., E. Moore. (New Farm. Q.): Glad?MG Ls heard so well up Numb. It Is nut SO,I..wn,ne u.m,. Cnre nnu haruu.-.r. eon good v,,.n you folk also. E. Suffolk (Lobethal, SA): Many thanks for the information about 5KA. I liked your pretty yellow envelope! G. Kelly (Shurnoilff, Q.): Pleased to get your several notes. Looking forward to that prom - it ed surprise. Thanks for the tip about 6WA nd Its actual location. Mrs. R. Esterhuizen (Milan[, SA): Hope you are out of hospital and quite well again now. Stuart is still around here, and would like to be remembered to you all. J. Fox, RNZAF: Glad to hear about your reception of Australians. Looking forward to the ZJV notes. R. Clack. All': Glad you're able to do a little listening now. It certainly Is a pity one Isn't able to obtain parts more easily. A. Cushen (Invercargill. NZ): 1. too, wish I had seen the Invercargill newsreel. Many thanks for the 4YZ notes. M. Vogel and F. Wilcox: Please advise us if the literature.von wrote us about has not reached you when you receive this issue. Printed and Published by Associated Newspapers Ltd. )successors to Sun Newspapers Ltd.) at the registered office of the Company, Elizabeth -street, Sydney. PAGE FORTY-FOUR RADIO AND HOBBIES FOR JANUARY, 1945

47 JANUARY, 1945 RADIO AND HOBBIES IN AUSTRALIA PAGE III. Morse Set. Highest Grade Adjust- Adjustable Morse Set. Buzzer, Batable Morse Key, P.M.G. Type, with tery. Fittings. Mounted ready for High Tone Buzzer. Mounted with use on wooden baseboard. 22/6. Battery. 21/6. Philips Blocking Condensers. 255 working test. 2 mid. 2/1, 3 mfd. S/8, I mfd. 4/8. BROWN'S BOOK OF SIGNALLING. Learn International Co d e s and Signals. All Methods Explained. Colored plates. Learn 15/- Set, Morse by Light Pies pnslage. and Sound Semaphore with Pro eedure, Ship's Signals, Flag Signals. etc.. etc. 11/ - posted. Jewellers' Magnifying Eye Glass for Stamp Collectors. Mechanics, Nickelled metal finish. 11/- Posted. etc. Levenson's Fun Book. For Home, Camp, BBtlemma. k Parties. etc. Endless Fun, Thousands of.s.za,.,a 1 Laughs. Jokes and Puzzle a, Ventrllotuism. Funny Stories. Card Tricks. Mono - Game s. Conjuring Tricks. Fun for Boys and Girls. Recitations, Card Games. Forfeits and other Features. New Party R.A.N. Games. New Ideas. New Jokes Price 2/9, 3/- posted. Buzzers for. Doors, OBlees,. Worksbons. Fac-_ tortes, &e., 3/6.: BARGAINS. 1 Gang Engplish. Variable Con- Highest densers, bath -tub type, with lid. 21/- plus onstage. liard. Lang -wearing. Serviceable Pocket or Belt Knives, for at. purposes. T h e Man la the Street, the Bushman, Seaman, Scouts, Men of the Services, v 3ttin. Steel Pocket Knife, one blade, tin-opener and marlin spike, 9/6. 3%in. Brass Pocket Knife, two strong blades. 9/3. 3l4in. Black Pocket Knife, one blade. Now Ready. 65 Postcard Size Photos of Planes and at. Canicula rs._,.. Renowned Planes In Fullest Detail. Aeroplanes in Detail from Original Drawings. A wonderful publication. 5/3. The best of Its kind. Gramophone Needles. 100 In box. each plays 5 records. 5/4 posted. Goggles for Industrial Work. Cyclists, etc.. 3/6. 3/11. 6/9. 7/9. plus postage. Electric Soldering Irons. Highest possible grade. One Year Guarantee. Flex 1/3 yard extra. Add sufficient postage watt Light Duty. 38/-: 100 -watt Heavy Duty, 16/6; 150 -watt Heavy Duty. 33/6. Folding Leather Pocket and Note Wallet Combined. Gold Stamped A.I.F'., R.A.A.F. or Symbols. 5/6. or 6/- posted. Aircraft Identification. prepared by the Publishers of "Aeroplane." 3/6 P.M.G. De Luxe Adjustable Morse Set on wooden base, with Buzzer. Light Switch and Battery. 30/ - "Like -a-flash" Safety Razor Blade Sharpener, with Paste. One blade lasts for months. For 2 or 3 hole All the World's Most 2 -sided blades. 3/-, or 3/6 posted. "Hite-Rider" Cycle Generator Electric Sets. Complete Head, Tall Light. with necessary fittings. Ill-, phis postage. Sin, Grade MAGNIFY- ING GLASS. Nickeach, or 4 elled Silver Rim and for 14/- plus postage. Full Handle. Substantially made. Splen- o didly finished. For reading or t pictures and other uses. 21hin, diem, 21/- and fullest Seoat Semaphore Signalling Cards. latest details. Part 1, British Mono- The Easiest Method 25/-: 31n.. 97/6 & 311/-: gin.. 33/11. et Self Instrue planes: 2, German Monoplanes: Lion. The Set 1/9 posted. Adjustable Metal t, American Monoplanes with the Case Buzzer. t.'3. R.A.F.; 5, Japanese Aeroplanes. CAR AERIALS. Aeroplanes in Detail, 4/6. From C Original Drawings. The best ever h ro m e d Metal, published. All the hest -known machines-british. German. etc. cne tin-opener, 8/9. 3%in. Steel Pocket Knife, one blade and bottle opener, 4/9. PLANS FROM LONDON. BUILD YOUR OWN MODELS. A i Yacht. A Simplified Method of Building a Bermudian Rigged Model Yacht from a Grocer's Box, 2/6. How To Build a Spacious Room Doll's Bungalow. Simple Plans and Detailed Instructions, Suggested Materials. Decoration Hints, etc.. 1/6. Simple Plans and Instructions for Building a Working Model Windmill. 1/6. How To Build a Floating Model of H.M.S. Nelson, 2/6. How to Build a Floating Scale Model Battleship. H.M.S. Duke of York. 2/6. A Handsome Floating Model of a Corvette can easily be made by you from these Simple Plans and Instructions. 2/6. All plus postage. RELIABLE CIGARETTE LIGHTERS. Small Pocket Tubular Type, as Illustrated. 10/6, or 11/- posted. With Removable Tops. Adjustable Flints. Flints Extra, 12 for 1/3. New Books. _Ideal Gifts.- Inc Design Construction of Flying Model Aircraft, fully illustrated, l7/-. plus postage. British Aircraft, by Sneath, 11/9. Plus postage. Fullest Details. Splendidly and properly illustrated. Solid Blade JUNGLE SHEATH KNIVES for men of Services, Bushmen, etc.. 33/6. with Solid Leather Sheath, 9%in. Overall 15in. Strong Wooden Handles. Serviceable Pocket and Bell Knives sold in NSW only. P.M.Ge'!^ are mum P.M.G. Type Morse Keys, 19/6. Adjustable Morse Code Rey with Heavy Plated Fittings, on Moulded Bakelite Base. Long or Short Tapper. 12/6. Adjustable Buzzers. 4/3. ROLEX CIGARETTE ROLLER, 4/9 posted. Makes 'em like the factory. Full Directions. British Products Just Arrived: Clear Celluloid Circular Protractor. 5e., 1/Ii Semi -Circle, lin., 4/-. Douglas Combined Protractor and Parallel Rule. 5/11. Three Section Telescopic Car Aerials. extendable 26 to 6$ inches, 35/-, plus postage. NEW BOOK JUST FROM LONDON. Simple Metal Works. 19/- posted. One of Famous "How To Do 11" Series. The Blade -saver Razor Blade Sharpener, with Strop at base. Easy to use. 3/-, or 3/6 posted. Sheath Knife, with Unbreakable Handle of Polished Wood, 14/- with Sheath, plus postage. Others 38/9 and 28/3. Sold in N.S.W. only. Morse Sel, Adjustable De Luxe. Bey. Buzzer, Switch from light to buzzer. Battery, mounted on baseboard. 25/-. T h e Handyman's Mirror, 10/9, or I1/ - posted. bin. handle. lin. mirror. A 1 I nickelled silver. For all Tradesmen. Radio Builders. Watchmakers. etc. See Into the corners and hidden places. It's all metal and beautifully made. Collins' National READY RECK- ONER, 12/6 posted. A most comprehensive volume. Cloth bound. "Etc." Radio Dials, illuminated. new square Bakelite Escutcheon, 15/ Dual Wave Type. 16/6. Both plus postage. The Seeand (Overseas) Edition of the British Radio Amateur's Handbook. 10/6 or 17/ - posted and packed, Containing 326 pages of the most valuable data on Modern Radio Science, and bas now been accepted as a Standard Textbook by many Signal Branches of H.M. Forces. The Section on Radio Transmitters Includes latest U.H.F. Apparatus and Television Technique. Strong 'ependable AD Metal TORCHES. Simple on -off Switch. Designed for use with 2 Standard Batteries (which are easily purchased). Our Reduced Price. Now 4/6. Tested and complete with Batteries and Globe fitted. Extra set of I batteries 1/6 plus postage. Postage on Torches: State, N.S.W.: Torch complete. Dd. with 2 extra batteries. 1/-. Q'Id., Vie.. and Tax : 1/-: 1/6. S.A., W.A., Northern Territory: 1/9; 2/-. Elco Dual Wave Dial, 21/-. Approx. Itt x Zit inch Oblong Escutcheen. The Greatest i pelt Problem Ever! u nma, tue Magic Axeman. OR with his head../6, or l/- posted. Steel cuts thru Steel. Pocket watch size. The Magic C- Rattle Box Trick. -Coins and small articles ( iyt disappear. So easy to do. So hard to detect. 119 posted. J. LEVENSON'S RADIO Games, Hobbies, Novelties, and Slot Machine Specialists, 226 PITT STREET. SYDNEY. Phones: M2525 and Goods forwarded C.O.D. Post or Rail over 10/-. (C.O.D. Rail within N.S.W. only, not Interstate).

48 PAGE IV. RADIO AND HOBBIES IN AUSTRALIA JANUARY, 1945 Ty,,FIYFiAs moat!/smh6th/jg3f1' WHAT'S STAFF SUPERI,, YOUR FUTURE? you look or any type of ' y.' ecause you belong to the ranks of the unskilled? If so, get to work immediately and join the ambitious young men who realise that Radio offers them limitless opportunities for advancement and an assured future. LOOK WHAT A.R.C. HAS DONE FOR THIS MAN "I'm blessing the day I started learning radio at the A.R.C. As things stand at present, I have earned enough to corer all my expenditures.»these include (1) the Course paid for, (2) turo meters value pre-war 26 - worth a lot more now, (3) four radios to learn on and experiment with, plus a fair amount of stock on hand value roughly 15; and best of nll, worth more than all, a decent future." H. B.. Western Australia. DO YOU KNOW? GLUING WOOD WITH RADIO WAVES. Incredible as it ;say seem an R.Y. "spot -gluer" has been tested under Active Service conditions similar to those of ordinary production. Exhaustive tests have clearly demonstrated that this process can successfully be used for tacking together layers of wood veneer. This operation is necessary to mould plywood shapes, such as aircraft fuselages wing elements, stabilizers, etc. Here is a great new application of Radio which speaks well for the future. Truly it may be said "Radio wonders will never Cease." SECURE YOUR POSITION IN THE POST-WAR WORLD WHILST FOLLOWING YOUR PRESENT OCCUPATION! YOU CAN START RIGHT AWAY Of the many industries crying out for skilled men, none is more important to the Nation-than Radio. We offer you the opportunity to enter Radio either in industry or In the fighting forces. Here are three good reasons why you will benefit if you become Radio Trained:- I. You will enter today's most progressive industry. 2. You will be pulling your weight in the war You will have a splendid career ahead of you when the war is over. COSTS Think of this-for a LITTLE few pence per day-actually less than many fellows spend on tobacco-you can prepare yourself for man-sized job in Radio. AUSTRALIAN RADIO COLLEGE PTY., LTD. Cnr. BROADWAY & CITY ROAD, SYDNEY. 'Phone M639I, M6392. ARC 1341 PREVIOUS KNOWLEDGE UNNECESSARY You don't need a knowledge of Radio or Electricity. We'll give you all you need of bothyou'll start at the beginning, building up knowledge just as carefully and systematically as you would lay brick after brick in its place when building a wall. You get the knowledge you want presented in a manner that makes it easy to learn FAST. A.R.C. Training fully covers Radio Service Men's Licensing Requirements for technical SEND FOR THIS BOOK First thing to do if you want to secure the facts about Radio is to send in for "Careers in Radio and Television," a lavishly illustrated book published by the College and available to approved enquirers. Send in coupon for your copy now. It's free and post free. To Mr. L. 8. Graham, Principal, Australian Radio College Pty., Ltd., Broadway, Sydney. 'Phone M Dear Sir-I am interested in Radio. Please send me, without obligation on my part, the free book, "Careers in Radio and Television." NAME ADDRESS RH,