Radio Review

Evening Star, Issue 19658, 10 September 1927, Page 16

Radio Review

■[By “HENRY.”]-

Flashes from Everywhere.

TERMS AND EXPRESSIONS. SIMPLE EXPLANATIONS. The following list is taken from Harmswortli’s ‘ Wireless Encyclopedia,’ and has been condensed and selected for this column by “ Henry ”: — Damping Moment—Term used for ono of the intrinsic constants of a vibration galvanometer. Daylight Effect. —Expression used to describe the difference of normal range of reception during tho daylight hours as compared with the night. It is well known that radio signals are received over greater distances at night than in the daytime, and there have been many dieorics advanced to account for this phenomena. D.G.C.—This is the standard abbreviation for the insulated wire known is double cotton covered wire. Dead Beat.—'When tho needle of a galvanometer or similar measuring instrument deflects from its zero position t may behave in two different ways, lb may take a smart swing from the in pulse received, and overshoot the nark owing to the presence of inertia n the moving parts, in which case it irst swings beyond its final resting •dace, retreats to a point somewhat hort, and successively oscillates to and ro in swings of diminishing amplitude 'util it at last comes to rest. _ Or nay move array from the zero point, on ■ocoiving its impulse,'in a more slugdsh manner, tho rapidity of its action lowing down as it reaches its final loflectional point, beyond which it lasses but a little way, if at all. In die second case the needlo_ would come o rest very much more quickly than in die first, and would he termed dead teat. Dead Crystal.-—Name used to describe a crystal without sensitive spots. Dead Earth.—This term is used in a number of ways, but more commonly : n the case of a complete short circuit. Dead End Effect.—Tho result on an iscillatory circuit of the presence of : dle .turns of an inductance. Dead End Switch. —Name given to a ■iwitch used for cutting out unwanted carts of the winding of an inductance coil. Deck Insulator.—Typo of insulator used on board a ship for insulating the aerial at the point where it is led through the deck or roof of the radio cabin. Detector Yalve.—A thermionic valve used for, rectifying radio frequency oscillations. It consists of a grid, a plate, and _ a filament, the whole enclosed within a glass bulb. D.F.—This is the usual abbreviation For direction finder. Dial.—ln radio work dials are used to control the movement of tho condensers, and various other portions movable in tho set. Diaphragm.—A thin disc, usually of soft iron, found in telephones and microphones, for the production or detection of electrical pulsations. Dielectric.—ln electricity tho word generally denoted a non-conductor of electricity—i.o., an insulator. It is usually ; confined to non-conductors when tlieir function is to separate neighboring conductors at different potentials. Direct Coupling.—The coupling between two or more inductances or circuits when tho connection is made by metallic contact. Direction Finder.—Apparatus so constructed as to indicate from which direction signals are coming. Direct Loose Coupling.—Term Applied to a metallic coupling between two circuits, when either the distance between the two circuits or when only a few turns in each of the coupled coils are common to both circuits. Direct Tight Coupling.—Term _ used in cases in which tho turns_ of wire in two metallically connected inductances are.in an appreciable ratio to one another. Double Cotton Covered Wire. —Abbreviated at D.C.C., this expression refers to a particular type of wire with a double coating of cotton insulating. Double Pole Switch.—A mechanical switch for interrupting both poles of the source of supply of electrical currents simultaneously by the movement of one handle or switch arm. Double Range Receiver.—-A variable inductance having two distinct inductances, one usually designed for short wave-lengths and the other for longer wave-lengths. Double Throw Switch.—A mechanical device whereby a current of electricity, reaching the 'switch by one terminal, can be handed on from one < or other of two separate contact points from which the current is taken to any desired point on the apparatus. Down Lead.—Name given to the wiro leading from the aerial to the radio instrument. (To be continued.} RUPERT HAZELL. Listeners to 3LO who have happy Recollections of the extremely diverting entertainment provided by Rupert Hazell and his clever wife, Miss Elsie Day, will be glad to know that this talented couple are having a very successful tour in South Africa. In a cheery characteristic letter to the studio Mr Hazel says that the fame of 3LO Melbourne has spread through South Africa like wildfire, and that he and his wife consider the time they spent in Australia as one of tho happiest in their long professional career. They both look forward to the day when they will make a return visit. ENGLAND ON SHORT-WAVE. DUNEDIN LISTENER’S SUCCESS. When it was announced that Mr Gerald Marcuse, the British amateur, was going to conduct a short-wave test for tho benefit of New Zealanders the amateurs hurriedly constructed their short-wave sets in tho hope of hearing the Englishman. Reports in northern! papers show,that Mr Marcuse’s station, 2NM. was hoard in the north on the occasion of his initial transmission. So far I have only heard of one Dunedin amateur who picked up the station. Ho writes as follows:—“ I beg to infqrra yon that on the 4th inst., from 7.15 to 7.30 p.m., I heard Mr Gerald Marcuse’s station broadcasting on 37 metres. This, I understand, was specially for Australian and New Zcaland listeners. Fading was noticeable, modulation was good, and I could hear without strain. Mr Marcuse called up 2FO, Sydney, and also a number of Australian amateur's. He gavo tho time as 8 _ a.m., signing off with ‘ Good morning.’ I was using a 3-valvo set, and had previously heard the Siberian station, RFM, four times testing on different wave lengths.” How many other listeners have been fortunate enough td hear Mr Marcuse P

HERE AND THERE. No doubt the old-time night from 3LO on Tuesday carried the older* listeners back many years, and recalled memories of the past. Reception of the station on that night was good. 4YA seems to be jogging, along quietly, and no one as far as I know has made any complaints about the station lately. So why worry? A South Dunedin listener complained the other day of the number of howlers in his district. “Can’t you do something?" ho asked me, and of course I had to answer in the negative. I hop© this catches the eye of the inspector, though. As far as the Australians go, 2FC is easily the best just now. Big Brother Bill took Aunt Diana’s place for the first time in the children’s session at 4YA on Tuesday night, I wonder how many young people ho will have in his brotherhood. The second talk about the Dunedin Exhibition camo in well from 4QG the other night. Considerable interest was aroused in England when the 8.8. C. broadcast a “running description” of the eclipse of the sun. Nearly two years ago SCL, Adelaide, broadcast a description of a partial eclipse of the moon. Sometimes the reception with a crystal set can bo improved by using several cat whiskers in a bunch. It is estimated that one in every twenty people in England owns a radio set. Those who hear the concerts from 3UZ, one of the two B class stations in Melbourne, will welcome the nows that the station will shortly increase its power substantially. The apparatus will bo much improved. Since 3LO moved to its new premises engineers have been experimenting with the studio drapings for the purpose of improving the transmission. Drapings eliminate echoes, but too much tends to make the music “ dead.” CARE OF DRY BATTERIES. Many wireless listeners who use dul emitter valves in their receivers have on hand large numbers of old dry cell* which are no longer capable of lighting the filaments of the valves. Especially in receivers in which only one or two valves of the .06 ampere filament consumption type are used these old batteries can be reconditioned to give ir. some cases several months of additional life (writes “ E.C.H.,” in the ‘Australasian’). About the easiest method of renewing rundown dry batteries is to obtain an old bit and with a brace di'il a hole about 2in deep into the top o each dry cell. The top of most drycoils is composed of wax or pitch, am it can bo easily drilled. Into the hole should be poured a couple of teaspoonfuls of a solution made by dissolving sal ammoniac, the salt employed for charging wet batteries of the kind usee: for bellringing, in water. The sal ammoniac can generally be obtained at any ironmongers, as it is often used lor cleaning soldering irons and for similar purposes. After the solution lias been absorbed by the battery the hole in the top should bo filled with molted wax or pitch, or even plugged up with clay. If the battery is a very old one it will probably bo found that there are many small holes eaten in the zinc-containing vessel in which the battery is made up. In this case the solution applied to the battery will soon soak out, and the battery will not Last very long.. A good way of restoring batteries of this kind is to convert them into_ wet batteries. This is done by obtaining a jar into which the battery and its zinc case will slip after the cardboard covering has been removed from tho battery. Several fairly large holes are made jn the zinc case of the battery, and it is placed in the jar. The jar is then about half filled with sal ammoniac solution. (n a great many cases the life of dry cells is considerably reduced by careless use. Many _ receivers contain a potentiometer, which is connected in tbs form of a resistance light across tho battery as long as the battery is left connected to the receiver. Although the potentiometer draws a relatively small current from tho battery, the constant drain it imposes rapidly runs the battery down. It is highly desirable that when dry batteries are used for filament lighting circuits which require the use of a potentiometer should bo avoided. If such circuits are used care should be taken to see that tho battery is disconnected from the potentiometer when the receiver is not in use. Merely turning off the valves by means of the rheostats will not be sufficient, as the potentiometer will still be loft in circuit with the battery run-, ning it down A further cause of rapid deterioration in dry batteries both for filament lighting and high-tension supply is lack of care in storing the batteries, Heat tends to set up chemical action in a dry battery which causes it to deteriorate rapidly, and it is therefore desirable that wireless dry cells should bo stored in the coolest spot available, while when they are in use they should never bo exposed to heat'. Dry conditions arc also essential, and damp and moisture dropped on to the batteries or around the table or bench on which they are standing will quickly run them down. VISITORS TO 3LO. 3LO, Melbourne, lias bach honored by tho visit of a whole string of Royal and other distinguished visitors lately, all of whom have had something to say over the air. His Royal Highness Prince Purachatra, of Siam, not only visited and spoke at tho studio, but made a special trip to Braybrook, accompanied by his entourage, to inspect tho transmitting station of 3LO. Being an eminent engineer and scientist, ho delved deeply into tho details of the elaborate plant at the station. Ho mentioned that reception of 3LO in Siam was remarkable. Among other distinguished visitors was Mr J. Garrick Eisenhorg, constructional engineer of the Radio Corporation of America, who has just completed the erection and organisation of a big broaden sting station at Manila for the Radio Corporation of tho Philippines, of which he was director. Still another visitor was Mr Franklin, Mayor of Perth, who spoke from 3LO on ‘ The Wonders of tho West.’ From Ocean Island, an outpost of the Pacific, came Mr J. I).. Cook, who was introduced to 3LO by Madzm Elsa Stralia. Mr Cook said that SLO was tho only station outside America, which was listened to regularly in the faraway islands of the Pacific. LONG WAVE TESTS. American experts arc at present experimenting with the idea of determining which _ is the best wave length for broadcasting purposes. Some of the experimenters say that the best results are .obtained between 1,000 and 1,600. metres, . Although a number of prominent radio men in America support this statement, the radio vested interests are opposing the removal of the broadcast wave band in the United States from the present wave lengths , of from 200 to 500 metres.

“ Henry '' will be pleased to answer any questions through this column relating to the fascinating hobby. Each correspondent must sign his name and address (not necessarily for publication). Newsy items will be welcomed.

* NEW ZEALAND .RADIO.’ In ‘ Now Zealand Radio’ wo certainly have an up-to-date wireless fortnightly. The latest issue has just come to hand, and, as usual, discloses a goodly amount of news and advice. Reports of reception of the different stations in all parts of New Zealand find a prominent place, and tho instructional matter displayed is under such headings as ‘What Plate .Supply Shall I Use’ and ‘Getting the Most From Dry B Batteries.’ The edition, however, is mostly confined to chatty talk regarding subjects which are being discussed freely in radio circles at present. NEW TRANSMITTER FOR 2BL. In anticipation of radical changes in broadcasting in Australia, arrangements liavo been made by 2BL for the erection of a new and powerful station near Windsor or Richmond (says the wireless writer of the _ Sydney ‘Morning Herald’). Tho high altitude of the site tentatively selected will give tills transmitter unique facilities for long-distance broadcasting. It is the intention of tho directors to ask for permission to increase the transmitting power considerably above live kilowatts, which is the highest power permitted by the Postal .Department for any broadcasting station' in Australia. It is contended by many radio experts that to prevent interstation interference all the broadcasting stations should be taken well outside the city area. This is in accordance with tho recommendations of tho United States Radio Commission. A further recommendation of tho American Commission is that stations used for advertising and propaganda purposes should bo licensed on condition that they use a minimum of power on the aerial, and that their transmissions be so modulated that they will not interfere with the entertainment programmes of tho first-class stations. A similar rule in Australia would, radio engineers contend, have satisfactory results by _ securing better reception of tho stations ivhoso programmes listeners, by their .icense fees, pay to receive. LAUGHING COMPETITION. Laugh, and the world laughs with you > . , Weep and you weep alone. Studio 3LO Melbourne literally shook ,i'itli laughter during the recent championship of Australia laughing competition. The several hundred competitors were summoned to the studio ,n batches, at different times, and the „ask of the judges was not as easy as me might suppose. There were all kinds of laughs, from ill sorts of competitors. A fat man imitated the laugh of a flapper, whilst a flapper laughed like an old man. Mon up in years imitated ladies, and ladies mimicked the kookaburra and the magpie. Big hearty guffaws followed slight little chuckles of a child, whilst outbursts similar to those of Sir Alexander Peacock were dovetailed in betiveen imitations of the efforts of baby kookaburras. All were hearty, and all spread the spirit of sunshine. The walls of tho studio echoed shrieks of laughter, and passers-by in the street wondered at tho sudden outbursts of unrestrained hilarity at 3LO. At a later date 3LO Melbourne will broadcast a demonstration of laughing by each of the prize winners. If they succeed in spreading tho gladness of things even to a small degree, and a cheerio even to a. few listeners, then this novel competition will have been well worth while. hawHf/s bay radio society: A meeting of the Hawke’s Bay Radio Society was held recently, but, owing to bad weather, there was a small attendance. It is hoped that the society will very soon have a transmitter of its own, after the stylo of 4ZB, Dunedin. A local paper states: —“Those of you who have heard the programmes of 4ZB, tho Dunedin Radio Society’s station, will have some idea of the pleasure that such a station gives to listeners, and there is no reason whatever why a station in Hastings should not he every bit as good as 4Z8.” GERMANY. In this country we do not hear very much of radio progress in Germany. There have been some remarkable developments in Germany, and its broadcasting stations arc acknowledged to be amongst the finest and most powerful in Europe. The concerts from Germany are listened to by English amateurs regularly. Germany has also introduced some now and novel designs for receiving sets. The aim in building receivers was to secure simplicity and thus reduce the cost. One result of tins policy has been the production of three valves m one. Not only does this valve contain the three valves scaled into one, hut it has all tho necessary equipment for coupling the three valves together. The valve is so efficient that it is only necessary to couple a tuner and batteries to it to make a complete radio set. It is hoped in time to have a valve without a filament, thus doing away with the A battery. RADIO AIDS ENGINEERS. By a mere chance experiment in South Carolina it was found that radio could detect detects in tramway rolling stock. Complaints had been received that the passing cars caused interference in the receiving sots, and to test if the cars were really responsible tor the interference a receiving set was operated from an aerial running parallel with the overhead tramway wires. The engineers were surprised to find that by analysing tho different noises made in the receiving set it was possible to detect faults not only with the overhead wires, but also with the tramcars, such as motors making bad contact, imperfect wheels, and defective brakes. As a result of these experiments radio receiving sets are largely used by electrical engineers throughout tho United States. In industrial concerns in Sydney, where there are many electrical motors in use for propelling different makes of machinery, it has been found that overloading and mechanical defects can bo detected by the trained oar of the electrical engineer by means of a radio receiver. WHAT HAPPENED TO 4ZB? Something went wrong with tho works at 4ZB on Wednesday night, and from 7 to 9.15 the station was on the air, but not a note of music came through. Some of the listeners wondered what had gone wrong with their sots, for all they could get was a loud and steady howl. That howl was 4ZB, and that was all the station sent out on Wednesday. At 9.15 the station closed down after broadcasting nothing.