NOTES AND COMMENTS

Radio Record, Volume I, Issue 47, 8 June 1928, Page 8

NOTES AND COMMENTS

By

Switch

‘phAT the yoices of famous present day men, transformed into radio Wives, are now wandering around the earth and may be picked up a century hence is the startling contention of engineers of the Marconi Company, London. Such waves, they say, never die out completely; with seusitive enough receivers they might be heard in 2028! Already they have heard programmes that have circled the world three times. Commenting on the idea, Dr. Lee de Forest, inventor of the radio valve, said:"Theoretically the waves exist for ever, 2s do those of the ocean. ‘The splash made by Noah’s ark is still in existence. Radio waves are too weak to be recorded by existing — re¢civers even a few minutes after their emission," ss ORD KNUTSFORIS © broadeast appeal on behalf of the London Hospital on February 35 resulted -in the receipt of no less than £20,000 from listeners. One subscription was received from Constantza on the Black Sea. An excellent proof of the enormous value of broadcasting, but one shivers to think of the possibilities of the art if it wefe used for propaganda. "THAT the possibilities in short-wave radio-considered unimportant a few years ago but now commanding interest by leaders in the new science -are far from exhausted is again indicated by discoveries of Abraham Esau, of Jena, Germany, that have resulted in his invention of a method to increase the power of short-wave broadcasting. Esau has discovered that a wire gauze placed on the surface of the earth under the antenna reduces the earth-current losses to a minimum, thus conserving virtually all the energy for radiation and giying greater distance. The network must be ‘three or four times the wavelength being used. Esau provides also for the saturation of the earth beneath the antenna with some chemieal agent, the nature of which he does not reveal, This improves the conductivity, he says. THE chief difiiculty which beset those who first tried to operate receivers direct from the alternating eurrent mains was due to the imperfect rectifying and filtering systems used. However, the development of the gaseous conductor valve which operated on the short path principle solyed these problems, and the use of these valves, together with specially designed filters and chokes, made possible the dream of the radio engineer and broadeast listener-all electric operation, The first commercially made eliminators suffered from many faults. The transformers and chokes were not designed to withstand the heavy currents which were passing through their windings, with the result that they burnt out. AH this has now been overcome, and we have at last the perfect all-electric set. A FRENCH astronomer, M. F. Baldet, finds evidence that the planet Jupiter, largest in the sun’s family, is shooting enormous volcanic bombs into space. Some of the comets and fire balls that sometimes hit the earth may come from Jupiter. Maybe Jupiter is responsible for some of the static we have been having lately. ‘ GREAT British astronomer, Professor J. Hl. Jeans, says the sun is ready to collapse at any moment. When it does, the carth will be frozen so cold nobody can live on it. Tz is surprising when one looks around té6 see the number of proadeast: listeners who employ the eareless method of leading the aerial through the Wall ventilator, or worse still, under the window sash. If one only thinks for a2 moment one must realise that the principle is wrong. It gnight do very well in the very dry weather, but what about the wet and damp weather? Some text books tell us that fully 25 per cent. losses occur through carelessly installed lead-in devices, PPWENTY times as many sets as are now being used would be needed to satisfy fully the potential world radio market, according to the estimate of the United States Department of Commerce. The 18,000,000 receiving sets now in use throughout the world serve about 90,000,000 of the earth’s inhabitants, or approximately 9 per cent. of the population of existing zones of constant radio-reception. If the zones of broadcast service were extended to include the whole world, 350,000,000 sets would be required. So the bugbear of radio "saturation" is still a good many decades in the future, ‘Vor short waves, ie., those below about 50 metres, do not travel along the surface of the earth, but are projected into space and reflected by the heaviside layer. For this reason the signals from short-wave stations may not be so strong near to the point of origin as they are at a distance of several hundreds, or even thousands, of miles away,

[ THINK some of us should sometimes send a letter of appreciation to the broadcast artists who please us. Your expeuse in connection with the wonderful entertainment you receive is very small. To encourage thé studio directors and the artists who are providing your entertainment why not sit down and write them a letter or a2 card of appreciation once a week? It is the only way in which they can tell whether their efforts are in the right direction and whether or not they are presenting the type of programme that you like to hear. VER £1740 was raised by the recent Berlin Radio Ball, and ufter taxes had been deducted approximately £1267 was ayuilable for distribution among yurious charities. N each one ot the 7700 guest-rooms vf the Statler hotels in six U.S.A. cities there are arrangement for radio reception, with a choice of two programmes. (Guests can have radio at any time without request or charge. In addition to the two programmes, which are looked after by skilled operators in the control-room, the hotel orchestra is sometimes "laid on," as well as ‘important speeches during banquets, In the larger rooms there are loudspeakers; in the others the *phones are placed in a drawer of @ table near the head of the bed. COATING of petroleum jelly or yaseline will preyent accumulator terminals from becoming corroded. FPINPOIL sheets may be used for "A shielding purposes, but care should be taken thut the condenser shafts and other components do not come into contact with the shield. Holes should be cut in the tinfoil, so that nothing can possibly touch it but the earth terminal to which it is eventually attached.

X, of Port Augusta, §.A., writes to | the Melbourne "T.istener In" :-‘I would feel very much obliged if you- | or any reader of The Listener Incould give me some information with regard to a station, which I have heard lately; and which uses the call sign 22M, ‘This station operates on about 278 metres, and is, apparently, a New Zealander in the Wellington district, but I have been unable to find this call sign in the ‘HMandbook." This is undoubtedly the Palmerston North station, 2Z1"°, 278 metres, the F sounding not unlike M at a great distance. It's about 1800 miles from Palmerston North "o the South Australian listener. DUST, dirt, or ebonite drilling may easily be removed from any awkward internal part of a wireless set by using a camel-hair brush mop. When the undesired matter cannot be swept straight up with the brush, it is only necessary slightly to damp the hair, or even breathe upon it, and thus pick up the dust on the brush tip. Rub the brush on a cloth, and repeat the procedure until all the dirt is removed in this manner. LARGE number of hospitals in Sydney now have radio sets installed. The Royal Prince Alfred Hospital, at Camperdown, has 500 headphones and 12 loudspeakers in use. The complete cost of the installation was £1100. The medical superintendent, W. A. Bye, when asked his views on the advantage of radio in hospitals, said: "Wireless in hospitals, in my opinion, is a great boon to the sick and suffering. It is very much appreciated by all patients who are well enough to listen-in, and it helps to pass many hours pleasantly, which would otherwise be long and dreary. It is especially appreciated by patients who are suffering from chronie diseases, necessitating long treatment, and whose convalescence is: slow. Altogether, I consider it a wonderful asset to our institution." } If transformers of too high ratio are used, distortion will result. If possible transformers of the same make should always be used when building a set, as some manufacturers wind these instruments in different directions, thus "ausing oscillation as soon as the audio Stages are turned on by means of the rheostat. The remedy for this is to reverse the leads on one of the transformers, taking the plate lead to B plus, and vice versa. A RATITER interesting demonstration of the loudspeaker-or perhaps one should say the super loud-speraker-was made some little time back over a number of New England (U.S.A.) towns, the people of which were suddenly surprised to hear a tremendous voice from out of the skies. As a matter of fact "the voice from the sky," as it is called, proceeded from a giant loudspeaker carried by an aeroplane, the whole arrangement being used for advertising purposes. The last stage of the low-frequency amplifier employed a set of four Western Flectric }-kilowat valves, fed at full voltage by a pair of wind-driven generators delivering 500 watts each. When the machine was 3000 feet up, the sound could be heard and the speech understood over a circle of 5 miles radius. During a flight of about 5 hours it was estimated that 300,000 people heard the advertising messages. UN LESS otherwise stated, valves of {he same make and characteristics shonld be used in a set, for valves of yarions mikes require critical voltage adjustment, WIE "dieletric’" of a condenser is the Insulator that separates one set of ‘|}plates from fhe other. Although the passage of oscillating currents "through" a condenser takes place with remarkable facility, yet at high frequencies a certain amount of energy is absorbed in the insulation or dieletric. and this is called a dieletric absorbtion loss, When air is the insulator between the two sets of plates, such a loss is negligible, and in a miea condenser it is trifling’ for all ordinary purposes Lut in paper condensers the losses can be comparatively large, and consequently for some purposes mica condensers are often specifically recommended, OR a small soldering job such as joining two twisted wires together, it is advisable to heat the joint well first, as the solder will then run through the joint and make a solid connection. QO prove that a condenser can be charged, and will hold a charge, connect one side of a pair of telephones to one side of a dry battery, and the other side of the phones to one side of the condenser. Now put the earphones on and touch the condenser with a lead from the remaining side of the battery. A loud click will be heard, and if the lead is removed and replaced several times, the clicks will become weaker as the condenser becomes charged. If clicks ave heard at the same strength each time the connection is madeyou will know that your condenser is short circuited. By connecting the charged condenser across a voltmeter, a& sharp movement of the needle will be noticed as the condenser discharges,

USTRALIAN listeners are puzzled as to the identity of a broadcast station, RJLO, heard on 450 metres. This is on 2 wavelength between 290, Sydney, 442 metres, and 3AR, Melbourne, 484 metres. "Switch" suggests that the mysterious station is either in China, or is a Russian Eastern station. "MANAWATU" (Palmerston North) } writes suggesting that the. Japanese station heard on the wave-. length of 4QG Brisbane, after the lat- | ter has closed down, is JOHK. He be: licves that the Japanese’s difficulty in pronouncing the H makes it sound like A, JOAK, he reports, is distinctly heard on a rather shorter wavelength -375 metres. | "DP M.O." (Remuera) writes that he. * yecently received the following reply from an American radio manufacturing company in response to his inquiry re A.C. tube sets:-"Our A.C, | tube sets are designed to operate at 115 volts with a margin of variation of 10 per cent. either way, giving a safe operating variation between 103 and 427 yolts. There are localities where lighting loads are not well balanced, and where the fluctuations are ex~treme, an A.C. tube set is not a desirable thing to use... . The tone prob- lems in an A.C. tube set are much more difficult than in the-battery type because of the so-called A.C.’ hum.’ "Switch" has seen several A.C. valve ‘sets operated in Wellington, and found ‘that they excelled in tone, the hum from the A.C. line not being audible, and they were not affected by line current fluctuations. HE saxophone, which has figured so | much in broadcast music, was, if is said, invented in 1840 by Adolphe Sax, who specialised in making wind. instruments for French military bands. A WRITER in the London "Popular Wireless" says: The Government of Colombia (South America) has ordered a broadcasting station for Bogota, the capital, and the presumption is that the service will be operated by the Government-at a dead loss, I should say. Colombia is a hot-bed of "atinospherics" most of the year, and is covered with mountains; hence reception will present some pretty problems, and a "regional scheme" would make Captain Eckersley think on all gears at once, | r With regard to the earth connection, it is too often assumed that any water pipe is a good earth, and earth leads 2ze sometimes found secured to waste pipes which never even enter the ground. If a water pipe is to be used, the main cold water supply pipe should always be selected. T your accumulator terminals are coated with a green deposit. this may be removed by a solution of ordinary washing soda, N ARCONI'S earliest experiments " with wireless waves took place in 1895 and 1896, when he used wavelengths half an inch long. Now some stations use wavelengths as long as 20,000 metres, equal to 787.000 inches! A German commercial station uses 2 wavelength 1,259,520 inches long. 2FC’s wavelength in inches is 17.397; 2BL’s 13,894 inches, and 8LO°s wavelength. in inches is 14,602. To find the wavelength in inches of any other station, multiply the number of metres in the wavelength by 3936. and | divide by 100. SOME have found it difficult to muder- | stand how a radio frequency amylifier amplifies weak signals more in proportion than strong signals, while an audio frequency amplifier amplifies strong signals more than weak ones, The secret lies in the fact that the radio frequency amplifier amplifies the yoltage applied to the detector valve, and is not concerned with increasing the power output, while the audio frequeney amplifier imust amplify the power available to actuate the diaphregia of the phones or the loudspeaker. Vibrating a diaphragm or cone and propageting sound waves that must run through thousands ef enhie feet of air and make themselves heard by Many ears requires imuch nore energy than it does to increase the grid potentink af a valve, ‘Bi every Australian State. with the exception of Western Australia. the number of wireless lieonses issued | in April showed An increase Gyer those issned in March. One imonth's in¢rease for New South Wales was "1141 licenses, A WRITER in the London "popular Wireless’ sayst--The 9 "ultra-super-short waves’ are now wtndergoing startling developments. Not until this year has transatlanutie work heen carried out on 10 metres, but it: has now been aceomplished four or five times, and the 10-metre ware, after the initial trouble in getting down there, seems fairly consistent, I am not forecasting the growth of broadcasting stations on 10 metres; but, after all, the whole spectrum of short waye-lengths has been brought into use very slowly, and. "a, bit at a time," and there is no possiljle reason why .the 10-metres band xhould not ultimately: proye ihe pick ,of the whole band