Radio Review

Evening Star, Issue 19841, 14 April 1928, Page 17

Radio Review

[By “HENRY.”]- —

Flashes from Everywhere.

TELEVISION. Television was first perfected by a young Glasgow engineer, who demonstrated that it was .possible to transmit over wires or through the ether not only the spoken word, but also the facial expressions of the speaker. A great deal of confusion exists in the minds of the public between television and the sending of photographs and pictures by wireless. Television is not the sending of photographs by wireless, but is the instantaneous transmission of living and moving Beenes. In the television process, whatever ia set before the transmitting apparatus is reproduced simultaneously, with every detail of movement, in the imago on the screen of the receiving apparatus. Tho ambition to achieve a form of television has been the cause of experiments for many years. The latest contribution towards tho accomplishment of what was formerly a scientific abstraction began in practical form five years ago with the experiments at Hastings, England. In January, 1926, the young Glasgow engineer (Dr J. L. Baird) was able to exhibit to the members ol the Royal Institution the feasibility of transmitting living human images with light and shade and detail at the first demonstration of television in history. At this early demonstration, however, an intensely brilliant light was necessary in the operation of the process, and this fact was advanced by the members as being the most serious, disadvantage which the system appeared to offer. After the demonstration Hr Baird made special research into the matter of reducing the use of intensely brilliant lights in transmission, and it was while he was engaged in this work that the idea occurred to him of utilising the invisible rays outside the spectrum. After considerable experimentation he achieved his purpose by the use of infrared rays, and in December, 1927, almost exactly twelve months after his first demonstration, Dr Baird appeared before the Royal Institution, and this time conducted the television operation in total darkness. Dr Baird explained his process in the following words:— “The image or scene to be transmitted is first of all turned into undulating electrical current. This current is transmitted in _ precisely the ■same manner as the voice current in broadcasting is transmitted, _ and lis-teners-in may bear the_ televicion signals as noises in their headphones. Each scene, or object, gives a peculiar and distinct noise. For example, different faces emit different noises. Phonograph recordings have been taken of different sounds given by individual faces, and it Is now possible to hear the sound of a moving face, the sounds of various familiar objects, such as a cabbage, a bowler hat, and a chest of drawers. These sounds,, if applied to a televisor, recreate on the screen the images of which they are the sound.” WAKE UP. RADIOLAND! One of the many thousands of Rugby football enthusiasts in New Zealand waxes indignant over the fact that the All Blacks’ exhibition game in Wellington Inst Wednesday was not broadens'.. Mj writes; “What were they doing in rad'oiniul when it came to pass that mm oi 1.110 most popular events of the month, to wit, tho All Blacks’ exhibition game in Wellington, was not broadcast throughout the land? True, the aetual result of the game was neither hero nor there, bub at a time when twenty-nine of tho thirty good men in action were national heroes who were about to leave these shores on the most important Rugby tour ever undertaken every detail of play would have been of intense interest to listeners-in. Those responsible for the omission deserve some censure. May they get it I” SIMPLER AND SURER. Radio sets of to-day differ greatly from those of two or three years ago. The design in the cabinets, the simpler operation, and the facilities for the obtaining of satisfactory volume are far superior to sets of years ago. The 1928 type of set is apparently a pinch simpler affair as far as its operation is concerned. Progress is indicated in tho changes that have taken place. The time was when we were all satisfied with a set so long as it made a lob of noise, bub that time has passed now. The novelty and wonder of wireless were perhaps the cause of that state of affairs. Then we went through that stage where we prided on the performance of sets containing a minimum of components, quite forgetting the feelings of our neighbors who had to put up with our receivers oscillating. Crystal sets and one-valvers are gradually going out of date, and enthusiasts are turning towards the more expensive "'ts with a view to having the concerts more _ comfortably and pleasingly. Evidently following the examples of tho motor car people, radio manufacturers are turning out yearly models. There should be many improvements in the future, but time alone can tell what form those improvements will take. HOW HINKLER WAS BROADCAST. Some idea of the quickness of thought and action required in the conducting of a large broadcasting station may bo gained from the transmission of the civic reception to Mr Bert Hinkler at Bundaberg, tho night the famous airman arrived at that citv (sas the ‘Listener In’). Extensive arrangements had previously been made to broadcast a description of his arrival, and those had bin carried out very successfully. Prior to his arrival, however, it had been very difficult to secure definite information regarding functions, and it was not until the afternoon he landed in Bundaberg that it was definitely known that at such and such a time a welcome would be accorded him in the Town Hall. A programme had been arranged at 4QG, but everything went by the board, when Hinkler was considered. Trunk lines were busy, and messages flow backwards and forwards between 4QG and Bundaberg. With lightning-like haste the Town Hall was connected by land line, and portable gear was installed. Then at a few minutes’ notice the studio programme was cancelled, and a change-over was made to Bundaberg. By virtue of the courtesy displayed by the Postmaster-General’s Department and the excellent line facilities provided, the speeches came over with “he utmost clarity. It was not known how long the welcome would take, and a jazz hand was therefore kept in attendance at 4QG. Shortly after 9 o'clock tho welcome ended, and 4.Q6 then changed back and gave a programme of dance music from the studio until closing down time.

AUSTRALIA AND SHORT WAVES. Such is one of time s vagaries that Monday’s Australian news is known in London on Sunday night. Hie news broadcast by 3LO during the early morning short-wavo session is listened to on the other side of tho world ten hours previously, and incidents are known chronologically belore they happen. On the other hand, British news, although transmitted and received simultaneously, is ten hours late when it arrives in the Antipodes. The simplicity of tho explanation does not rob tho peculiarity ol its interest, and to the child mind it is a source of endless thought, besides being an object lesson in chronological reckoning (writes a Melbourne correspondent). Tho spectrum oi the sun and stars can be dissected one color Irom the other until their virtues or disadvantages for use of mankind can be accurately analysed and calculated. It can be ascertained irom tho color ol the light of the stars what minerals they contain. Their weight and distance can be measured and their movements calculated with precision. Such is tho march of science. Soon the phenomena of wireless will be known—fading and distortion will be overcome and the way opened up lor continuous telephonic communication the world over. Some Australian stations arc .doing much to elucidate these problems by conducting regular short-wave broadcasting services. _ They are also carrying out extensive fading and distortion tests, besides endowing special research at the Melbourne University. Imagino every A chus broiulcastuig station in Australia being brought together in some lorm ol amalgamation or co-operation so that bands and artists could bo transferred and kept continually 011 tho move in a circuit. Think of tho saving of effort and cost of a centralised control of the broadcasting services. Even opponents to unification as a principle admit that there are paramount reasons lor centralisation of wireless broadcasting control, because tho decentralisation of operations and tho accruing advantages would by far outweigh tho tendency to bureaucratic methods. Overlapping ot programme items would bo obviated, and tho system would result in a IUO per cent, improved service generally. AIDS FOR THE NOVICE. An Australian radio publication gives the following hints and tips for the beginner;— Hereunder are sonic good suggestions for the erection of aerial masts:--Wooden poles whose total length is 20ft to 25ft should bo set ole in tho soil, 30ft poles 5.5 ft, 35ft to 4011 poles 6ft, 45ft poles 6.5 ft, s(Jft to 55ft polos 7ft, 60ft poles 7.5 ft, 65ft to 7Oft poles Sft, 75ft poles B.oil, and 80ft poles 9ft. Ordinary three-ply vcncor wood makes good panels for receiving or transmitting sets. Veneer is cheap and easy to obtain: it is thin and will not warp. A panel made of thin veneer wood is almost as good as a bakclite or hard rubber panel, if the wood is thoroughly dry and seasoned. It would bo a good plan to bake tho veneer panel in a warm oven for a half-hour to make sure that there is no moisture left in the wood. When a three-circuit. (primary, secondary. and tickler windings) having fixed coupling (tho coupling is determined by tho distance between tho primary and secondary windings) is constructed tho builder bus to choose whether to place tho primary and secondary windings close together (tight coupling) and get good volume of music, but poor selectivity, or to place them further apart (loose coupling) and get good selectivity but not so much volume. The best placing of the primary and secondary will have to bo found by experiment, because tho proper degree of coupling depends to a great extent on tho nearness to powerful broadcasting stations. Either volume will havo to bo sacrificed lor selectivity, or vice versa. The selectivity is good when a set tunes “sharply,” and poor when it tunes “ broadly.” Electric light lines or door bell wires running parallel to a transmitting aerial will often pick up a quite heavy current when tho transmitter is operated. . Tho amount of current thus absorbed by the electric light wires is just that much energy stolen from tho transmitter. This absorption is particularly troublesome on the short amateur wave lengths, because tho natural period of the aerial formed by tho door bell wires is often the same us tho wave length of the transmitter. A bad ground connection will cause endless trouble, and is about the last thing to be suspected. Too little attention is paid to ground connections. Undoubtedly tho best ground connection is mado by soldering a length ol wire to a water pipo and connecting this wire to the ground terminal of tho receiver. Gas pipes should not be used. If a water pipo is not available twist a sheet of copper into a conical shape and fill it with charcoal, and bury it in a damp place. USE THE VALVES PROPERLY. A complete discussion ol the proper plate and grid battery voltages to use for every type of valve would take too much space, but a lew general bints should prove of value. Complete rf<tulications and operating characteristics of valves are given in tho sheet ot instructions regarding their proper use which valve manufacturers supply in the cartons in which their valves are packed. These specifications, regarding the proper filament voltage, plate voltage, and grid bias to use with such valves and tho uses to which the valves can be put, should be studied carefully before the set is designed and wired, so that full advantage can bo taken of the knowledge gained by the manufacturers in the experimental and development work which has been done with the valves. The following is a resume of next wek’s programmes from 4YA, as published in the ‘ Radio Record ’: — The service from St. Paul’s Cathedral will be broadcast to-morrow_ evening, when the Rev. Canon Nevill will preach. Under Mr James Dixon, the St. Kilda Band will provide the majority of items on Tuesday night. The music will include an arrangement of Irish melodies. One or two other artists are billed, and Pastor More is to give a humorous address. Another light type programme will be put on the air on Thursday night. Gems from ‘ Going Up ’ and ‘ Our Miss Gibbs,’ Hawaiian music, and humorous songs, etc., will be put through tho microphone. There will also be a relay from the Octagon Theatre. Among the performers on Friday night will he Miss Irene Horniblow, Mr J. B. MTherson, Miss Florence Sumner, Miss A. D. Allan, and Miss Shiela Neilson, all well-known artists from 4YA. ' Saturday night will see another of the usual_jnixfA psatrrwgpies.

»• Bennr *• will be pleased to answer any questions through this column relating to the fascinating hobby. Each eorrespondent must sign his name and address (not necessarily for publication). Newsy items will be welcomed.

ACCUMULATORS. The accumulators are an expensive item of equipment, and are also capable of giving considerable trouble if not taken care of, and if neglected or misused they will certainly bo ruined. Probably the most general fault among amateurs with regard to their accumulators is in providing those of inadequate capacity. Generally speaking, so Jong as the accumulator heats the filament of the valve or valves to a sufficient temperature, it is taken for granted that all is well. This does not necessarily follow, however; if tho accumulator be a six-volt one and the valve filaments will heat sufficiently at four volts, the accumulator can become 25 per cent, discharged before becoming ineffective, which is extremely bad for it. An instrument rarely seen among an amateur’s kit, but which should be present wherever accumulators are in use, is the hydrometer.' A hydrometer is no more expensive than a cheap voltmeter, and a cheap voltmeter is worse than' useless, because it will probably be inaccurate and therefore misleading. If a voltmeter is used to judge the condition of your accumulators, remember that the readings must be taken when they are discharging through the normal circuit. A much better way to determine this is by moans of the hydrometer. In a fully-charged battery tho electrolyte should have a specific gravity of 1.25, and should never fall below 1.15 when the accumulator is practically exhausted. The level of the electrolyte should bo kept just above tho plates. Loss by evaporation should be made good by the addition of distilled water, to bo purchased from a chemist; loss by spilling should be made good by adding fresh electrolyte, obtained by mixing pure brimstone sulphuric acid with distilled water to give a specific gravity of 1.25. Tho dilute acid of the correct specific gravity, 1.25, could bo obtained ready mixed from a chemist, or tho two obtained separately and mixed as r; aired, provided a hydrometer is available. Buy your acid and water from a chemist, and you will get it pure. If you obtain them elsewhere, be sure they are pure. Remember, never add water to acid when obtaining the dilute acid: great boat will bo generated, the vessel probably break, and you might lose your eyesight. Mix acid with distilled water drop by drop, stirring meanwhile, and always in glass or earthenware vessels. If it is proposed to charge and maintain your own accumulators yon are counselled to obtain tho maker’s instructions, or otherwise read up the subject. It cannot bo too strongly emphasised that any trouble taken to ensure that your accumulators arc charged by a cajiable man will be amply repaid in added efficiency and increased life. — 1 Listener In.’ ' A HOME-MADE VERNIER. A non-removable top binding post, with only a little alteration, will serve as a first-class vernier for radio dials. Obtain a post of generous size. If you have one around the workshop, which you discarded because of the corrosion of its brass parts, it will do nicely. Screw the top down very tightly, closing the gap permanently. Gut a piece of fine-grained cork to the same diameter as tho base of the binding post, and 3-16 of an inch thick. Cut a hole in it to allow for the passage of the screw. Apply a little good glue to base of the post and force the piece ol cork on; the pin will hold it in place. A small brass washer is needed between the cork and the panel. After the nut is adjusted behind tho panel, an extra nut should he put on to lock the vernier at a fixed tension. HERE AND THERE. A Dunedin listener, in Christchurch during Easter, stated tho other day that 4YA’s harmonic can be heard in tho north quite plainly. On Sunday evening last 2ZF, Palmerston North, was heard in Christchurch louder than 4YA. is there. Although only Jour degrees lower on the dial than 3YA, tho Palmerston station did not suffer very much from interference by Christchurch. A concert such ns we had from 4Y r A last Thursday week was a welcome relief from tho monotonous stuff wo have had to put up with lately. The banjo solos, the humorous sketch by Mr Percy James and Miss Billy Lorraine, and, in fact, the majority of the items were very acceptable. Give us more like that lias been the general cry since. Cue of tho most popular broadcasts on a Saturday afternoon last year were the relays of football matches. Tho New Zealand stations did not do such a great amount in this line, but it is to bo hoped that this year will sco football on the air more frequently. 4YA, please take notice. Has it ever struck yon how popular an early morning session would be in Now Zealand? To begin' with, it would make for general brightness by commencing the day with music, and with ,tho_ health interest quickly following with the “daily dozen.” Lots and Jots of information could he sent out in tho morning if our stations were on tho air; but they are not, and apparently never will be. Thirty shillings a year ought to buy ns a morning session as well as tiro afternoon and evening broadcasts. Sometimes one comes up against the problem of determining which is tho negative and which is the positive pole of an electrical circuit on a dynamo. An easy solution of this problem is to hold the two wires about an eighth of an inch apart on the surface of a freshly-cut potato; the positive pole will produce a greenish colored spot on tho surface, through acting on the starch contained in the potato. A receiver embodying two dozen valves is now in use for daylight reception of 2LO in America. It contains but twelve sections, each stage of amplification using two valves in parallel. The set is used for daylight rchroadcasting of London, which is now a regular feature in America. With tho formal opening of the new radio sending station at Zeesen, fifteen miles from Berlin, Germany now possesses by far the most powerful station of the kind in the world. I notice with the nightly programmes that 3Y T A has not been publishing the times the various items are being put on. That is a procedure that could bo very easily followed by the other three stations, in view of the fact_ that they do not keep to their advertised times. A person wishing to hear a particular item from a certain station, looks up tho advertised time of that item in the newspaper, and tunes his set to the station at the hour given. But in ninety-nino times out of a hundred he won’t hear that item, for the simple reason that it has either been' put on or will not be broadcast for another half-hour. Hence the suggestion that the stations leave the times out of their advertised programmes.