NEWS AND NOTES

Radio Record, Volume I, Issue 12, 7 October 1927, Page 8

NEWS AND NOTES

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. Three-inch dials are about as small as will afford snitable gtip for operating and four-inch’ dials are better. Even a three and a half inch is better than the smaller size. If small dials are used, -however, the principal tuning control ought to have a large dial and knob. Fine adjustment is impossible with a tiny knob. . a ae Failure :to obtain a receiving license. -in Greece, as required by the Director of Greek Telegraphs, Telephones and Posts, may result in twelve months’ imiprisonment and a fine of 100,000 drachmas. Licenses are somewhat less ex~ pensive. ‘The General Electric Company recently demonstrated its short-waye radio telephone equipment designed for use on long freight trains for comn:unica‘tion between engineer and conductor. Although the train was a mile and a quarter long, not the slightest unreliability was observed, the signals being ‘oud ‘and clear under all conditions. Up ‘ta this time, it has been necessary for -the conductor to use the emergency ‘brake to stop the. train or to rely on .whistles or flare lights which often fail because of bends in the tracks or poor weather conditions. ‘ "Many persons buy wet ‘‘'B’’ batteries, connect them to the set, place them on a shelf or at the rear of the table and forget them. The top of the batteries and terminals collect large quantities of -dust, more or less moisture and suffer corrosion from various fumes. ‘‘B’’ bat‘teries should be. protected from dust. They might well be placed in a box with a lid. Dust causes leakage and spoils the contact at the terminals. Dust holds moisture, which adds to the leakage and helps corrode the terminals _ Mr. Merlin H. Aylesworth, president of the National Broadcasting Co., of ‘America, said to an interviewer, recent"ty -"We know for a certainty that big --

things are just around the corner We expect that we shall live to see motion pictures flashed on to the walls of our homes. Science may even find a way to break down food into electrons and transmit them to our kitchens by radio and there reassemble them for nourishment This sonnds like the wildest nonsense at the moment but the radio itself seemed like nonsense only a couple of decades ago." 5 In his address hetore the Radio Manufacturers’ Association, assembled at the Chicago Trade Show, Federal Radio Commissioner Orestes H. Caldwell poimted ont that, in six years of broadcasting, the radio industry had succeeded in placing radio equipment in but one-fourth of the twenty-two million homes of the United States. Considering that. there are eighteen million pleasure automobiles, sixteen million wired homes, sixteen million telephones and eleven million phonogtaphs, the radio industry has a lot of unfinished business ahead of it The 1927-1928 sea son will see a marked change in the ratio of radio to non-radio homes -- The phones are a useful accessory to any valve set, and are indispensable for a crystal set. If the phones ute poor crystal reception will be weak, and with a valve set it will not be possible to receive long distance stations, because the weak current that flows through the telephone windings will not be strony enough to actuate a movement of thie diaphragm. Be sure that the phones are of good make and avoid disappointment. The ordinary form of neutrodyne receiver is not well suited to operation with a loop aerial The reason is that a coi] aerial] is employed primarily to obtain. directional reception, by the proper orientation of the coil. Such a loop would in general have magnetic coupling with the radio-frequency transformer coils, thus resulting in regenera. tion. While there are some ways in which this effect can be avoided, as bv completely shielding the receiver magnetically, there seems no great object in using 3 loop aerial, since 1 very short indoor antenna will give as good reception and will not require adjustment,

The recent shortwave broadcast trans missions by 3L,0, Melbourne, have pro= vided an interest’ng illustration of how short waves ‘'skip’’ over short distances and come down to earth again at great distances from the station. Round about Melbourne, the short-wave transmission from 3L0 is very much weaker than the transmission on 3L0’s long wave, ale though the power nsed by the two stations is abont the same. In spite of the weakness of local signals, however, 8L0 is being heard by listeners at distances of 10,000 miles and more very loudly and clearly. This is beéanse the waves travel high up in the air, passing over the tops of nearby receiving aete ials, and thus affecting them very little and then returning to earth again at great distances to produce loud signals, -. Over in Kenya Colony of British East Africa, 12,000 miles away, Americats broadcasting is being heard regularly. This was made known in a commuticae tion received by WLW, Cincinnati; from the Kenya Radio Company at Naie robi The letter states that ‘ experlments conducted in the colony prové that it is easy to receive American short wave stations, using a receiver consist+ ing of a detector and two stages of audio frequency.

The layman often expresses the’ opin+ 1on that seeing short-wave transmissiom carries tremendous distances, our broad« cast stations-should operate on shortwaves The fact is that the short waves skip nearby areas and come to earth at an immense distance In countries of huge areas like Australia, simultaneon$ short and normal wave broadcasting May prove a success Radio players are proving very popuy lar among listeners in South Australia, and 5CL is adding’ to their interest by broadcasting some really good "‘effects,* Listeners got a thrill recently while # ghost story was being broadcast, to heat a bodv being dragged downstairs, while on another occasion a revoiver shot was | fired in the studio. It is interesting ta | recall that the first recorded attempt ta the sound of a shot resulted in a major breakdown at the London broadcasting station 240. The sharp noise of the report was responsible fot a sudden surge of current in. the trans ‘mitting equipment which was so its tense that it broke down the insulation on the thain modulating choke coil and mecessitated a closing of the station for several houra.

An Amertican scientific writer presents information relative to the nature of space surrounding the earth. Three layers of gases are said to be found varying in height and having different temperatures, The lower layer or blanket, about seven miles high, contains mixed gases and varies considerably in temperature. The middle layer, about 80 degrees below zero Fahrenheit, is about 25 miles in height. The upper layer, about 400 to 600 miles high, is supposed to have a temperature of about 80 degrees above zeto Fahrenheit. This latter is said to serve as the protecting blanket, surrounding the earth, against the many meteors which would otherwise destroy everything on the surface. It also serves as the reflecting layer for many radio waves, being commonly called the Heaiside Layer. It is ionised by the aurora is said to be displayed. Above the ultraviolet rays from the sun. In it this layer, space at a temperature ot 460 degrees below zero is supposed to exist. Strange though it may seem a great many listeners Have not bought a hydrometer for use in testing their storage batteries. This is the only instrument that will accurately tell one the condition of the battery. And if the battery is not charged at certain intervals its life is materially shortencd. It is an investment, not a luxury, to procure a -hydrometer. The heating of a filament rheostat is uo cause for alarm. The very purpose of such a device is to waste scme of the current from the battery, so that the amount flowing through the tube itself cau be regulated. The retarded electricity is dissipated in the form of heat. Some aerials receive very much better in one direction than in another, -and this applies particularly to long low aerials in which the lead-in is taken from the end of the aerial. Tests have been made frequently, and it was found that an aerial not more than 100 feet in length and not less than 80 feet above the ground has very little directional effects. In aerials where the directional effects are noticeable it usually will be found that the horizontal length is equal to or more than four times the vertical height, and in constructing an acrial fans should try to avoid such a condition. The use of a straight line condenser to tune the secondary circuit will facilitate the tuning of any receiver, When using these condensers the increase in wave-length is proportional at the degrees of the dial on the condenser and this makes it possible to plot a straight line wave-length graph for the receiver, By referring to this graph, in which wave-length in metres is plotted against the degrees on the secondary condenser dial, it is possible to find the approximate dial setting for any station, the wave-length of which is known. Crackling in the phones may be caused by a broken phone cord. After the phones have been used for some time the fine braided wire in the cord gets’ broken in spots. ‘The test for this is to Shake the cord. If the noise continues with the shaking get a new phone cord. It is frequently difficult to locate the mounting screw holes for instruments to be placed on a panel. If you have to template place the screws in the holes of the instrument to be mounted, place white ink or other colouring matter on the heads of the screws and insert shaft in its hole, allowing screw heads to come against panel. Remove and drill where spots of colour are left. Never unscrew the caps of telephone receivers unless absolutely necessary. There is the double danger that the diaphragm may be bent, and the hairlike wire on the magnet coils broken | If the average valve is allowed to burn in a horizontal position it will cause the filament to sag, and this will change the operating characteristics of the valve, and will also shorten the life of the filament. It is, therefore, wise to mount the valve in a vertical position, Cushion supports made from sponge rubber could also be placed under the valve socket whenever possible, as this helps to absorb mechanical vibrations which cause noises in the receiver, In using a crystal detector :t will be found that each one will vary in the respect of which direction the current enters. Some operate louder when the current enters through the catwhisker and others when the current enters through the crystal and leayes through the catwhisker. Try reversing the terminal connections, and a difference will be noticed in most cases. To many listeners who are just building their first set the most difficult problem encountered in the construction is the determination of just which wires are connected and which are stil: to be connected. ‘To eliminate this uncertainty as each wire is laid in the set the corresponding line in the diagram -+hould be crossed out witl a coloured pencil line. It is generally not advisable to add a third stage of audio-frequency amplification to any set; the third stage never gives the expected amount of amplification and it is always noisy, in fact so noisy that the music is sometimes lost. A new audio amplifier, however, is now marketed in America, with three stages. A potentiometer is just what its name implies, that is, it is a potential meter. In radio receiving sets there are many uses for a potentiometer, one of the most common being to regulate the grid otentiometer, When a potentiometer is employed for this purpose the resistance coil is connected directly across the "A" battery and the slider is connected to the grid return of the valve,

|EMPIRE BROADCASTS AN BMBASSY COMING é VISION OF THE FUTURE. Recent -successes in international: broadcasting by stations in Europe and the United States and tater the re-| broadcasting in. Great Britain of a programme from 2FC, Sydney, ‘have created intense. interest in Great Briain, There has been a_ strong demand that the British Broadcasting Corporation, which is controlled by the British. Post Office, shonld instal a short wave transmitter of high power similar to successful European and United States transmitters for Empire broadcasting. Engineers of the Broadcasting Corporation, however, have taken a strong stand against this proposal, declaring that wireless telephony has not yet been developed sufficiently to permit successful and dependable Empire broadcasting to be attempted. Led by the Wireless Association of Great Britain most wireless interests have strongly criticised the stand of the Broadcasting Corporation. A communication was received in Melbourne recently from the secretary of the Wireless Association’ of Great Britain (Mr. H. A. Hankey) stating that he will visit Australia, New Zealand, and other parts of the Empire shortly to obtain technical evidence confirming the possibility of establishing Empire broadcasting services. SMALL BOOM COMING. Broadcast listeners are going to take up short-wave reception in great numbers before long, and radio dealers will advisedly prepare for the boom by laying in stocks of short-wave component parts. ‘The wireless writer ot the Melbourne ‘‘Argus’" says:-It seems certain that within a year or twe hundreds of international shortwave broadcasting statious situated in all parts of the world will be work- | ing." INCREASING SELECTIVITY 4 A NEW IDEA VENTILATED. "Nature," of August 13, 1927, says: -the ether is becoming s:rions1y «ver crowded with radio. waves. Two or | mor: stations having nearly the same official frequency often "jam" one another in an ordinary receiving set. The problem of inventing a simple method of cutting out the interfering stations is, therefore, one of great importance to the radio engineer. In a} paper read by G. G. Blake to the Radio Society of Great Britain on May 25, a description is given of a method of improving the selectivity of a receiving set by means of ordinary sound resonators. The results obtained were most encouraging. Even when several stations were working with considerable mutual interference and bad atmaspherics were present, it was found possible to isolate the selected station by means of a sound resonator. It is concluded that there is no reason why many more frequencies could not be selected for stations in the wave bands at present employed for broadcasting. The author suggests that by the use of a hot wire microphone and a number of sound resonators _ each tuned to a different station, all the signals could be heard ‘or recorded simultaneously. He points out that the hot wire microphone or thermotelephone receiver was described by Sir William Preece to the Royal Society in 1880. It consists of a_ tightly stretched fine -platinum wire fixed at one end and attached at its other extremity to the centre of a diaphragm. The wire is heated by a current from a battery, and the expansion or contraction of a wire in response to words spoken towards a microphone in series with it cause the diaphragm to vibrate. Concerning the recent short-wave coneert broadcast by 3L0, Melbourne, a Melbourne writer says: ‘‘No one expected 100 per cent. of success at this early stage. The British Broadcasting Company, older, possessed of special research scientists, aided by amateurs with years of experience, has not yet been able even to make a start in world broadcasts. 8L0 has gone much further than its older brethren among stations. ‘The success on September 6 was a qualified one as far as trans mission went. Heard clearly in Java, less so in Japan, the signals were picked up fairly in Holland, and a certain speech was heard in London in the Jatter hours of the Wednesday mornine’s transmission, as night there was falling. That measure of success is gratifying to a station which had just begun to operate its short-wave | instruments." |

j A proposal which may seem fantastic, but may be some day realised, is made by an English correspondent, G. Chapman, in "Wireless World" (London), to the effect that, with the increasing demand for television, a worldwide wave-length should be set aside for synchronising signals. A highpower station, according to this plan, would be devoted to sending forth standard-frequency signals of this -kind, by which all television machines conid be regulated, as well as_ radio clocks operate. While in the future, ‘this idea seems like one which may be ‘practical with the development of the art. , | 2

The new broadcast station at Innsbruck, in the Tyrol, relays Vienna programmes on 294 metres, 5006 watts. This station is linked with the studio by four hundred miles of land-line. Of this distance a large portien is covered by power lines, over which the programmes are sent at radio frequency. They are again stepped down at Worgl, 45 miles from Innsbruck, and complete the journey by regular telephone cable. A high-power, long-wave — {900-1300-meter) station has been established in Warsaw by the "Polskie Radjo" broadcast company: It has a 100f-watt output, and is erected on the Szczesliwice fort outside the city. The height of the masts is 275 feet. pare