Radio Review

Evening Star, Issue 19794, 18 February 1928, Page 17

Radio Review

[By “HENRY.”]

Flashes from Everywhere.

BEGIN AT THE BEGINNING. More than half of those who d; '.c in radio have not the slightest knowled o of the fundamentals of this fascinating hobby. Therefore it is my inJ Mitioii to try to start the listener where he ought to start—at the beginning. Radio waves travel through the air, but they do not travel on the air. They travel on that mysterious medium known as the ether. When a stone is thrown into a quiet pond a wave disturbance is set up, spreading in all directions from the point where the stone entered the water. Radio waves can be likened to the water waves, only in place of tho stone an electrical discharge is responsible for the waves. The ether waves travel silently and at a speed of 186,000 miles per second. As they travel in all directions any receiving station situated at any point of the compass will bo able to receive the message. The length of the radio waves is measured in metres, which belongs to the metric system, and is equivalent to 39.37 in. Therefore a wave length of 200 metres is equal to 200 in x 39.37iu, or 7,874 in. A 200-motre wave, or one of any other length, may travel several thousand miles Recording to the power of tho transmitter. MR HARRIS SPEAKS. —Broadcasting Manager’s Views.— The band contest which is to be held in Christchurch this month is not to be broadcast. This information has been conveyed to the Broadcasting Company, whose application to broadcast has been refused. Referred to on the matter, Mr A. R. Harris, general manager of the Broadcasting Company, said that the secretary of the Band Contest Committee had stated that the reason for the committee’s decision was that it refused to give the Broadcasting Company “something for nothing.” “There is apparently a misconception amongst some people regarding the functions and duties of the Broadcasting Company,” said Mr Harris. “In the first place it is not the Broadcasting Company that is getting ‘ something for nothing,’ but the attraction that is broadcast on relay. It costs tbe Broadcasting Company considerable money to broadcast, and the persons whose performances are broadcast no additional expenditure. Neither has it any adverse effect on the attendance. As a matter of fact, it has been proved that considerable benefit accrues L- the attraction broadcast due to the publicity given. “Tho Radio Broadcasting Company of New Zealand’s, Ltd. position is not that of a private company formed to exploit the public, but that of a public company formed under Government regulation to administer a public utility m the interest of tho community. “ The company appreciates that it costs racing and trotting clubs, hand associations, musical societies, and such like public institutions a considerable amount of_ money to provide their form of entertainment, and it is their business to decide whether they shall or shall not permit broadcasting. The company also appreciates that these institutions are giving in their own way and at considerable personal effort and expense service of the greatest public interest. However, as the Broadcasting Company’s service is also given in the public interest, it cannot for this reason make direct payment for relays, although it is prepared to co-operate with such institutions to the extent of providing the broadcasting service without any cost to them.” ABOUT TELEVISION. Almost every day we hear something of the wonderful television apparatus that scientists in almost every country are working so hard to perfect. Promises of cheap “ televisors ” in the near future naturally cause some people to look forward confidently to having the attachment on their existing receivers within a month or two. If the televisors are obtainable in the near future and do not come up to expectations, the public is likely to harm radio to some great extent. Any new device that is being tested is talked about and enlarged upon, with the result that when the apparatus is put before the public it does not come up .to expectations. During the last two years wo have been told about the great televisor, but we haye not yet been shown any demonstrations of it, nor has any practical application of it to the ordinary user been given in any other part of the world. _ There certainly have been demonstrations of the new art in America and Europe, but the exhibitions, while more or less successful, have been on an experimental scale, and not one of them has shown how the system _ can be applied with any degree of simplicity to the great army of listeners. Therefore we should not look forwardwith keen anticipation to television equipment being on the market for some considerable time to come. We must just be content to listen to the radio programmes and picture in onr own minds what the singer or lecturer, etc., looks like. In an _ English magazine a writer gives a picture of a scene in ten years from now. He shows the telephoned party whose likeness is on the televisor plate at the end of the telephones unable to deny that he is not at home, or even condemned to the boredom of an engagement he does not want to make. Television surely has its bad points. NEW SHORT WAVE STATION. A correspondent advises that there is another short wave station in Japan operating nearly every evening from about 10.30 to after midnight. The wave length is slightly above that of 2AQ, Taihape. On Monday night last he received the station at good ’phone strength on three tubes. The announcer did not give the call sign, but it was keyed instead in very slow Morse half a dozen times, J.H.8.8. was the call. Again on Wednesday night, at 11 o’clock, the station was coming over at greater strength than previously, and the call letters were given in English. A talk_ in a foreign language followed. Previous to Monday night the station had been heard fairly clearly transmitting songs and instrumental music. The songa were very monotonous items. THE ENGLISH AMATEUR. MARCUSE’S SCHEDULE. Mr Gerald Marcuse (2NM). the ■hort-wave amateur, is now on the air regularly as follows:—Sunday, 6.30 to 8.30 p.m.; Monday, 4.30 to 5.30 a.m., and 6.30 to 8.30 a.m; Thursdays and Saturdays, 11.30 a.m. to 1.30 p.m. On Wednesdays he will broadcast at 6.30 p.m. All times given are New Zealand Jimes. The writer would be glad of any reports of reception of 2NM,

RADIO IN JAPAN. Japan is now in tho front rank of radio science. Indeed many letters [torn experimenters there indicate that they have nothing to learn from those iu Western nations, who have so far had many advantages over experimenters far removed from the chiot centres of radio development. Reports received by 3LI) from listeners in Japan disclose a marked thoroughness and exactitude in their experiments—a thoroughness which is characteristic of our Eastern neighbors in their adoption and development of Western methods and inventions. Immediately following tho invention of the thermionic wireless valve, Japan not only developed and improved its application, but also manufactured it in largo numbers; these _were used considerably in ship’s equipment and in land stations throughout the world. Wireless operators are familiar with the old Japanese “ sausage ” valve which gave such efficient service during the Great War period. There are many excellent Japanese radio journals now in circulation, one of the most important being ‘The Radio No Nippon.’ THE CALL SIGN. Although a call signal like 4YA, Dunedin, becomes well enough known, this method is not quite satisfactory; _ unless it is repeated before every item there is difficulty in identifying a station. Some stations, for instance, have an annoying habit of seldom announcing who they are. and, if to this is added an unreasonably long interval between items, the annoyance is aggravated. It is remarkable how one exaggerates the length of that interval of silence. Such intervals are the cause of many caustic criticisms, and the station _ directors should reduce them te a minimum. In outside broadcasting the failure to announce the station’s identity is exasperating. Some programmes from concert halls have been known to continue for over two hours without any announcement. In some cases it is not an easy matter to have the station call sign mentioned, hut there is no excuse for continued ignoring of a simple and very desirable practice. FOR Sr IT-WAVERS. A difficulty encountered in short-wave reception, which may be readily overcome, is the correct value of the gridleak. Tho gridleak value is generally around three megohms, and sometimes as high as live, depending on the valve use-f as well as the characteristics cf the circuit. And since it is a fact that even the best metallised gridleaks vary within 10 per cent, of their rated resistance value, it is obvious that no precise resistance value is obtainable for the gridleak, except through tho cut-and-try method. Some experimenters report trying as many as 100 gridleaks before they have obtained a suitable value for the valve employed. This difficulty is readily overcome by employing a variable resister, which covers tho necessary range of resistance, is noiseless, and holds its adjustment. This variable resister is shunted with a grid condenser of .00025 mfd. •> The wiring of the short-wave receiver is an important consideration. It should be remembered that we are dealing with very high frequencies, and that there is a considerably larger field about each conductor than in the lower frequencies of broadcast reception. Therefore, the components should be spaced further apart, and the wiring should be quite open for proper spacing. The three-valve short-wave set, with regenerative detector and two stages of audio-amplification should occupy as much baseboard space as the usual six-valve broadcast receiver. s 3LO’S SHORT-WAVE TESTS. WORLD-WIDE INTEREST. The success achieved by 3LO in its world-wide short-wave tests has focussed the attention not only of wireless enthusiasts,, but also of tbe general public in all parts of the world for Australia. In this way 3LO is per;j.".rung a national service for the Commonwealth, in a double sense. The valin of the short-wave tests from the wireless viewpoint is obvious, and it requires but little thought to reach the conclusion that the publicity given Australia must greatly increase interest there. English, American, Japanese, Dutch, Indian, Canadian, and African people are learning something of Australian land, pastimes, and high literary and musical taste. Letters from every great country on tho globe have reached 3LO as a result of tho short-wave tests. Messages, songs, and music broadcast from 3LO on tho short-wave between 4 30 and 6.30 on Monday mornings are received in America on Sunday afternoon. New York is 8,000 miles away direct, but the wireless waves travel 16.000 miles in darkness to reach that country. It is well known that the sun throws out waves of electricity, and the wireless waves take the course of least resistance, through the darkness. The last overseas mail to 3LO contained a letter from a listener in Ocean City, New Jersey, paying tribute to the .success of the broadcast. Others have’been received from Porta Delgada, in the Azores, from the Dutch East Indies, and literally hundreds from England, India, Africa, and Asia. EVER TRIED THESE? A simple gridleak can be made by drawing across a piece of paper a line about one and a-half inches long. This should be done either with a black lead pencil or with Indian ink. Two brass binding screws are arranged, to make contact with the line and act as terminal screws. The resistance of such a line depends directly _ upon its length, and inversely upon its width and thickness. Blotting paper is the most suitable kind of paper to use for this instrument, which is a very necessary component to a valve set. When using several pairs of telephones together on a crystal receiver it is usually advantageous to connect them iu series with one another. This is done by taking the connecting tips of the various pairs of telephones and joining them as follows: One tip on one pair of telephones should be connected to one of the telephone terminals, the other tip should be joined to one tip of the second pair of phones (this can be done by binding the two tips together with a piece of bare wire), while the other tip of the second pair of telephones goes either to the remaining telephone terminal, or, if further telephones are used, to one of the tips of the next pair, and so on, so as to form a chain of all the tips, the two extreme ends being conpeered to the telephone terminals.

"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.

HINTS FOR LECTURERS. Among the hints drawn up by the B.C.C. tor improving the microphone technique of radio talkers arc the following ; “ Avoid parentheses, long sentences, and difficult words. Do not try to crowd too much material into a quarter of an hour. It is hard for listeners to concentrate when they cannot see the speaker. in , particular, avoid enumerating the points you have no time to cover. It is important to avoid a monotonous delivery on a level note. “It is well to begin a now paragraph in a different tone from that used at tho end of the preceding paragraph. The great thing to remember is that you are not speaking to a massed meeting. Tho declamatory note is therefore wrong. Hundreds of thousands of your listeners are sitting alone in their own homes, and to find themselves addressed as a public meeting would be absurd. The note of intimacy, as in conversation with a friend, is the note to adopt. FIXED CONDENSER TESTING. About the simplest test for leakage in a fixed condenser is to put it in series with a 46-volt B battery and a volt meter, if the needle on the meter shows a distinct fluctuation the condenser is apparently defective. If a condenser is charged by being placed across tho terminals of a 45-volt B battery, it will register a voltage when it is subsequently discharged by having its terminals placed across the terminals of a volt meter. This discharge will! merely swing over the needle, which will then drop back quickly. But .the length of swing is a fair index of the storage capacity of the condenser. It should also retain its charge for an appreciable period, after it has been charged by having its terminals placed across a 90-volt B battery, giving a spark when its terminals are joined after a few minutes. If touching the terminals of a condenser across the B battery terminals causes a spark each time, when the operation is performed, say, every second, tho condenser is probably “ leaking,” and defective. The foregoing tests work out bettor with condensers of -ijmfd. or larger. A DX TIP. The following suggestion may seem rather fantastic, but it is worth while trying if you are a DX “ lan,” aud stay up late at night nursing dials in an effort to fill your log book with the call letters of distant stations, take a tip from the transmitting amateurs and use a small opaquely-shaded bulb as the only source of illumination in the room. Turn out all tho overhead clusters and wall brackets, then set the lamp on or near your operating table, so that it is below the level of your eyes and casts a glow only strong enough to make the dial readings on the receiver discernible. A more effective expedient in easing the reception of the elusive DXers you have never found. The weakness of the light has no effect on the receiver, of course, to increase the latter’s sensitivity; but it has a marked effect on your physical and mental condition that directly facilitates reception. With a dull light in the room you unconsciously relax your mus cles, put yourself at ease, and rest your eyes. You sit back comfortably, and the inactivity of your other senses tends to sharpen those of hearing and feeling. You are not distracted by a strong light, but only feel the soothing effect of a soft and indirect one. You are able to concentrate fully and comnletcly, with only your ears and fingers active. RADIO AND THE TRANSTASMAN FLIGHT. Wireless was the safeguard that was lacking. That is how the ‘Listenerln’ sums up the recent transtasman flight, which ended so tragically in the death of two of New Zealand’s airmen. The paper states:—“Although it is true that they carried a wireless equipment that was installed during the last week and overhauled by tho assistantmanager of Amalgamated Wireless on the very eve of their departure, the utmost use they could make of it was to let the world know by means of signals sent out every fifteen minutes that they were in tho air. As an indication of their position it was of little use unless hey flew direct on their course. “Neither of the aviators, it is certain, was an expert radio operator, and if, as assumed, they crashed at sea, it is unlikely that they could have notified their position, even if they knew it. “There is no doubt that in all transocean flights, comprehensive radio arrangements should be made beforehand, and that one of the fliers must bo a fully qualified radio man, or where only two can go, the navigator should have a thorough understanding of tho radio apparatus used. In an ideal flight three direction-finding stations should be used to keep a constant check upon the ’plane’s course, so that should drift occur, the fliers could be immediately notified. This would not entail any strain upon the operator, since a small wind-driven automatic signalling device could bo fitted to send continuously the call letters of the ’plane. Then, if they did crash, their exact position would be known immediately. “ In the Ryan monoplane emergency apparatus was useless, because tho machine was practically all metal, and would sink immediately. Certainly it appears as though the airmen placed too much confidence in the ’plane, and did not attach sufficient importance to the radio equipment. This disaster merely proves, as did those of the fatal Atlantic flights, that efficient radio is necessary, also a good operator. “Their instruments were their solo guide across the Tasman, and if one of these failed they may have missed New Zealand altogether, due to drift or incorrect compass reading; but if a radio beacon or direction-finder had been employed this would not have caused more than a passing thought. Now, before a commercial air passenger service to the dominion becomes a reality it is certain tha radio beacon systems will be erected.” DISTANT RECEPTION. IS IT WORTH WHILE?, “ Is distant reception worth raving?” is the heading in an English magazine to an article which reads:— “ While there will always be a number of enthusiasts who will be fascinated by any new circuit or set the maker or designer of which claims that it will bring in numerous stations, there are to-day a very large number of listeners who prefer clarity of production to distant station logging and simplicity to knob-turning. “ One often finds two-valve sets recommended fat, loud-speake? yrorkjiftg,

when to obtain adequate volume entails the use of as much reaction as possible, spoiling the general tone of reproduction, while the provision of a h.f. stage_ would have added just the needed additional signal strength to have allowed the set to have provided sufficient volume without being pushed. In these days with improved valves of low current consumption, undue economy in the number of valves is not worth while, particularly so if the h.t. supply is taken from the mains, which it can conveniently be by all electric light users. H.t. consumption, whore dry batteries are used, has. in fact,- become a much greater problem than l.t. current consumption, as modern valves do not make a heavy call on the l.t. accumulator, but they do, and particularly the power valves, make a heavy drain on the h.t. dry battery. ‘'Even when distant stations have been obtained by means of a super set; there still remains the bugbear of atmospherics to he dealt -with. One cannot tune out atmospherics, and the more powerful the sot the more trouble this nuisance causes, especially during the summer months. Reasonable selectivity, such as that provided by most modern sets, gives the average listener all that is required in the form of alternative programmes.” BIG BEN WRONG. A difference of fifteen seconds between London’s Big' Ben and the Sydney G.P.O. was noticeable recently during a rc-broadcast of 2LO. Usually they are heard simultaneously, the chimes, when 2BL puts both on the air, being completely mixed together. As tho speed of -wireless waves is ns fixed as the law of gravity, it cannot he said that the signals took longer than usual to reach Sydney. Sydney postal officials claim that the G.P.O. clock is always correct to within five seconds, according to Observatory time. Evidently Big Ben, then, was at fault. HERE AND THERE. A new station is to bo opened in Japan. It will be situated at Osaka, and its power is to he about twice that of 2YA. Construction is to commence very shortly. When completed the station should be heard here quite loudly with four or five valves. What has happened to tho band concerts from 4YA on a Sunday night? The St. Kilda Band, although still playing" at the beach, for some unknown reason is not on the air now’, but its place was once ably filled by the Kaifcorai Baud. Now we have to be satisfied with gramophone records, which, when all is said and done, give us music by the best bands and orchestras in the world. On about forty metres two-way radio telephone communication is being carried on between Holland and Java, and short-wave enthusiasts in New Zealand will find it possible to pick up the conversations. No secrets will be let out of the hag, however, as the conversation will probably he in Dutch. An amateur Sydney station, 2SP, was recently heard in Johannesburg with perfect clarity. A number of radio messages w r ere picked up from the ill-fated liner Principessa Mafakla, which recently sank off the Brazilian coast. One of the last was a dramatic note from the heroic radio operator _ himself. “Am locked in my cabin,” it said. “Don’t know what is happening, except that aitain has ordered mo to call for p.” The League of Nations js_ installing a radio transmitter that will have a range to cover all of Europe and parts of Africa and Asia. With the additional construction of four powerful receivers the work will cost, approximately £25,000. Montpellier, France, will soon boast of a twenty-kilowatt transmitter,’ which is being erected by the French Posts and Telegraph Department. Short-wave work in Japan is practically at a standstill, as the Government has curtailed short wave amateur activities. Reception of 2FC is becoming a favorite pastime in America. A new day and week-end telegram service “ via Marconi ” was opened recently in England.A workhouse at Home js_ to be instilled with wireless receiving equipment at a cost of £290. According to the manager of the Radio World’s Fair, held in Now York recently, more than twenty-five large radio manufacturers sold their entire output for,the 1927-28 season. CORRESPONDENCE. “Help Wanted” (Kaikorni) writes: 1 am thinking of constructing a set, using four or five valves. Which is the better circuit—the neutrodyne or the aperiodyne? Probably the better circuit of the two will be the neutrodyne, if built with j-eliablo components.