Radio Review

Evening Star, Issue 19800, 25 February 1928, Page 18

Radio Review

[By “HENRY.”]

Flashes from Everywhere.

MORE LIGHT MUSIC WANTED. NEW ZEALAND PROGRAMMES TOO HEAVY. In the last few mouths the broadcast fare from the New Zealand stations has improved beyond words. Especially so is it the case with 4YA. The artists engaged at all stations are among the best the various cities can offer. But still we are not getting the class of programmes we want. Although not of a classical nature, the programmes from stations are of a very high standard—in fact, a little too high. The average listener does not want too much of dramatic songs and music emanating from the brains of masters. A little jazz popped in hero and there would gladden the hearts of a good many license holders. And what a deluge of quartets are being showered upon us at the present time. Quartets are all very well in their place, but the broadcasting station is not their place—every night in the week, anyway. “Enough is as good as a feast,” said one listener recently in speaking of the programmes from New Zealand stations, “ I like tho good stuff as well as anyone, but a jazz night at all stations would certainly be a welcome innovation.” At least a dozen others have expressed the opinion to the -writer that they do not get enough of the light type of programme. The average working man who sits down at night after a day’s toil to listen to the radio would much prefer to hear light orchestral and vocal _ items to high-class music. Comedians in this city, at any rate, are hard to find, hut jazz orchestras are not. 1 remember some time ago that Mr Bellingham (musical director of the Broadcasting Company) said that tho type of jazz" bands in the dominion was not good enough for broadcasting, and that all dance music should be done by tho gamophono. Mr Bellingham was wrong when ho made that statement. Not so long ago ji really good concert was given from 4YA by a local jazz orchestra, assisted by other artists. Tho programme on that occasion was not permeated with big overtures, symphonic poems, etc., but was just a straight-out concert of light music. And the listeners liked it, ton.

THE YEAR REVIEWED. RADIO IMPROVEMENTS. In an American paper Ernest Ingold give: a review of the year’s improvements in tho radio industry. Ho writes:— For three years manufacturers have stated that there was nothing particnlarly new in radio, and this year is no exception. Tho long waited for radical changes are still, seeminglyfar in the future and progress is confined to a gradual refinement and perfection of already known principles. So, once again this year, expect nothing radically new and, at the same time, the suggestion may be added to beware of anything radically new. In tho reputable lines—that is, those manufactured by factories with financial standing and adequate engineering staffs —sets made two, three, four, and even five years ago still operate satisfactorily and still give their owners excellent reception. The sets shown for this year bring nothing particularly new to radio, but do show that tho principle of continual refinement and improvement has been carried on even further; perhaps the word “simplification ” tells more of what is being accomplished than any other word. A noticeable improvement has been made in cabinets. This will probably always bo so, and just as changes in design of furniture come continually, so it is also possible always to produce improvements in cabinet design and in cabinet finish. An increasing proportion of the number of sets sold are being sold in a cabinet of some kind or another. Most of the cabinets so far on the market have used built-in speakers, although cabinets are now being shown in which tho speaker, as it is originally manufactured, can be fitted into tho cabinet, leaving the design and production of the speaker to tho electrical manufacturer and the production of the cabinet itself to the wood-worker. There are now on tho market a na.abor of good B eliminators, and the B eliminator may generally bo accepted as having reached a stage where any one of several reputable makes will give satisfaction. It apparently is not having any pronounced effect on the popularity of the more orthodox installation—namely, that of batteries; and batteries, because of their low initial cost, long life due to recent improvements, and because they are so thoroughly understood will always continue popular. The same thing does not quite hold true of the A power unit, which is still to a very largo extent in the experimental stage, and the particular units which will prove satisfactory in tho service of owners have not yet proved themselves. Rerhaps the best suggestion that can bo made on tho use of power units is not to try any experimental product but wait until time and exuerience have - proved the merit o l ' the appliances. It is very noticeable this year that there are fewer manufacturers who are producing radio receivers, the past two years having seen a process of elimination and concentration. Those who own receivers made by well-financed concerns of prominent character find their service and maintenance problems are nothing at all. Those who bought nonamo sets, probably at a liquidation salo of some kind, will do well to consider placing in their homes a receiver thoroughly established on tho market on which a dependable service will be available continuously. The usual crop of stories and rumors about the “ ultimate ” sot have been current. No doubt at some time the perfect set will be available, but tho prospective buyer will do well to avoid all material in anything like an experimental stage and not purchase any set on which the principles of operation have not been proved by several years of ownership or owner use. Lot the other fellow experiment. Buy standard merchandise made by companies in tho radio Inisiness to stay. Follow practices and use equipments which have been proved successful, because they have been on the market for some time, and yon will have entire satisfaction. MANUFACTURE OF EBONITE. How many listeners who employ ebonite for their receiving panels know how the black substance is manufactured? Very few. Well, here is a short description of the process ebonite goes through in the making. Ebonite is composed of pure plantation rubber, to which have been added various ingredients, the most important of which is the necessary sulphur for its vulcanisation. The best quality ebonite is made of pure rubber, while the cheaper grades are made from rubber gums of an inferior quality. The very cheap qualities of ebonite contain but little rubber in their composition, and the writer advises the pun»iaser to leave these severely alone, as, quite apart from their brittle nature, they have in most instances very poor insulating properties. The first stage in the nfanufacturo of ebonite is the “grinding” of the rubber between the rollers of the rubber mill. One roller travels at twice the speed of the other, and thus pinches and rubs the rubber, generating a considerable amount of heat in the process. When tho rubber has attained a smooth plastic state the ingredients are successively added and ground in. This having been completed, the rubber dough is taken to another mill and calendered or rolled to an exact thickness (usually about an eighth of an inch for sheet ebonite); sheets 6ft by 3ft are taken, laid one on tho other, and well rolled together till the thickness bf tho desired finished sheet has been attained. These sheets are then placed in rectangular iron frames, and their top and bottom surfaces covered with single sheets of tinfoil. This imparts the gloss to the sheets. The frames are placed in a steamheated press and subjected to the required degree of heat for a certain period (this varies with the thickness of tho sheet) until vulcanisation is complete. The frames are now removed, tho tinfoil rolled off, and the sheets of ebonite are ready for use. 3LO’S NEW ORCHESTRA. A new orchestra lias made its appearance at 3LO, Melbourne, with considerable success, 1 believe. It is the largest broadcasting orchestra in tho Southern Hemisphere, and included in its personnel are some of tho best musicians in Australia. The organiser was Mr Will Quintrell, who was well known on tho Australian stage. 3LO Station Orchestra is to be the name of tho new band, of players. Joe Aronson, who was in charge of the previous orchestra at 3LO, has accepted an engagement elsewhere, but several members of his symphonists have joined the new orchestra.

Wagner, Beethoven, Weber, Tsdiaikovvsky, and others gave us some of the greatest music the world has ever known, and those who execute their works from the various stations do so with skill and artistry. Nevertheless, I repeat that we can have too much of £ good thing. The stations would do frell to employ a jazz orchestra at least ®nce a week and to include more light atuff in the programmes for tho sake of those who cannot understand heavy music. All classes have to bo catered for, and one man’s 30s for a license fee is as good as another’s. Let the stations give us more light music, and then everyone will be satisfied, | ABOUT YALYES. Unlike Tennyson’s brook, valves do not go on for ever. No, Ido not mean that the filaments burn out, but they lose “emission.” When this occurs in an h.f. or detector valve the result is always dissatisfaction on the part of the owner. He finds his tuning has gone “ flat,” and he cannot get the stations he used to. The one and only cure is to buy new valves. Take every precaution in saving the life of a valve. A high-tension fuse is always worth while. One of the little torch lamps with a voltage of about 2.5 connected in series with the battery makes an excellent fuse, and one that no one will ever grumble at replacing when it is remembered how much a valve would have cost had tho fuse not been there. AERIALS AND EARTHS. Aerials and earthing systems require periodical attention or noticeable depreciation in signal strength will result. Seo that the aerial wire is making good connection to the “lead-in” tube; clean the end and sandpaper the terminal on the outer end of the tube. _ Also, if possible, clean the aerial insulators—it is really surprising the amount of grime they accumulate. If an earth plate is used now is the time to make sure that it is still intact and that the earth wire is making good contact with it. Where a water pipe earth is used see that the clip is in good order. Resistance in tho earthing system is a frequent cause of bad tunings and distorted signals, and it should bo borne in mind that it is just as essential to avoid “joints” in the earth lead as in the aerial wire. Where they cannot be avoided a good soldered connection should always be made. This point is often not appreciated to the extent that it should be. CONSTRUCTION OE A FRAME AERIAL. The E.M.F. induced in a frame by a passing electromagnetic wave is approximately proportional to the area of the trame and inversely proportional to the wave length. Frame aerials are therefore more efficient on tho relatively short broadcasting wave lengths than oji long waves, and largo frames are more efficient collectors than are small ones (says tho “Listener In”). As a counterbalance to the relatively high efficiency of frames on short waves, wo have, however, the fact that shielding effects become pronounced as the wave length decreases, and for this reason reception by a small frame is often very poor when attempted on the ground floor of a house surrounded by trees or other houses with their water pipes, lead roofs, etc. The obvious remedy is to install the frame as high up as possible, and : there will be found in most houses a space between the top floor ceilings and the roof, in which can bo rigged a suitably large frame or frames permanently fixed in the right direction. A supply of 2in nails, some reel insulators, and a reel of No. 22 S.W.G. double cotton covered copper wire is all that is required for the construction of the aerial, tho down leads may be run on cleats inside the house or out under the eaves, down tho out- . aide of the house in one span, and in through a convenient window sash. In any case, the down leads should-be well separated from each other and from the walls. In using frame aerials it is well to bear in mind that the best results are usually obtained with a small value of tuning capacity. The valve is a potential operated device, and with a_ small tuning capacity the potential variations are high. There is a tendency to instability insomo amplifiers, however, if this is carried too far. A 25 vane variable air condenser (0.0005 mfd. max) is ■uitable, and the total length of wire required to make a one-turn frame tuning to broadcast stations with such a condenser is about 80ft. For a small ten-tern frame, with Jin spacing beStems tcras/Wft wire will suffice.

•* Henry will bo pleased to answer any questions through this column relating to the fascinating hobby. Bach ©orrespondent must sign bis game and address (not necessarily for publication). Newsy items will bo welcomed.

IMPORTANT S.W. DEVELOPMENTS EXPECTED. Important developments in the construction of short-wave receivers are likely to he one outcome of the invention of the new English shielded plate receiving valve (says an exchange). The main effect of tho shield is to reduce the capacity of the valve almost completely. In the ordinary valve the capacity between the plate and the grid is comparatively great, and the valve really resembles a small condenser. The effect of this, if the valve is used as a high-frequency amplifier for very short waves, is that the capacity of the valve acts ag an almost complete short circuit in the valve itself to an incoming signal impulse. The consequence is that an incoming signal passes right across the valve without being amplified, and no gain is obtained in the high-frequency amplifying valve. This effect has hampered the construction of a short-wave receiver incorporating a high-frequency amplifier. Tho new screened valve, however, will overcome this weakness of tho ordinary valve, and its influence may ultimately bo greatly to increase tho scope of short-wave broadcasting. At present the real value of short-wave broadcasting is partially limited to the transmission of programmes from one country to another for rebroadcasting. The majority of listeners hear the programme after it is relayed, instead of picking it up direct from the overseas station. It is likely, however, that tho use of screened valves in high-frequency amplifiers will result in tho production of a simply operated short-wave receiver, which will give fairly consistent loud-speaker reception from short-wave stations in all parts of the world. The value of this will he that the listener will be able to tune in whatever overseas station he likes. RECEPTION OP 2NM. A correspondent writes:—“l did not listen-iu last week-end, but three previous week-ends I have heard 2NM testing. Monday morning, January 30, was very good for reception, as I had 2NM on the speaker, using three valves, and the same morning 3LO, Melbourne, was well received in England. It was 7 o’clock when I tuned in, and 2NM was coming in as loud as 3LO. I thought it was 3LO until I heard tho announcement. There was no fading, except the slow fading out ns tho sun rose, and at 7.45 I had lost him completely. Monday morning, February 6, was nob too good, as the music was weak on the ’phones, and 1 was just able to hear the announcement, hub on Monday, February 13, at 6.45 a.m., ho was at good ’phone strength, and volume increased until 7.5, when it started to weaken untiMt faded out about 7.30. Some Morse interfered one morning, but otherwise speech and music were very clear. I have not listened in at other times corresponding to the tests, but will do so in the near future, and will let you know what the results are.”

FOR BETTER RECEPTION. Never paint the coils of a set with any kind of paint or varnish, and do not use any material of this nature to stick the turns of wire tightly together, or otherwise there will be losses in the coils. In a crystal cup of the typo in which the top or cap is screwed down to hold the crystal in place, it will sometimes be found, especially if a small fragment of crystal is being used, that the latter cannot be fixed tightly even when the cap is screwed home. To overcome this difficulty take a piece of tinfoil and crumple it in a small pad; place this in the cup first to raise the crystal a little, and then screw down the cap. Add more foil if necessary. If the hole in the cap is too large, roll some foil into a little stem and bend this round into a ring, and lay on the top of the crystal. A brass washer may even be used upon the top of the crystal. Dull-emitter valves using a small accumulator to heat the filament are sometimes subject to variations of signal strength which have the same effect as “ fading,” When this occurs, it can often be remedied by connecting a fixed condenser across the battery. A suitable value for the condenser is .002 microfarad. When the filament fails to light the cause may be duo to many other defects besides a burnt-out tube. The “ A ” battery switch or connections may be open, dirty contacts may be on the rheostata, socket or valve tips, or the valve may not be seated properly in the socket. A simple means of making battery connections when there are no binding posts and no clips or clamps available is to drive a nail into the top of each terminal post. Each post is of lead, and the nail can be readily driven in to make positive contact without injuring the battery. The wire is then wrapped about the nail as tightly as possible to complete the connection. If the connection is to stand for a considerable length of time, it should be coated with vaseline to protect it against corrosion. WIRELESS OR CABLES? In these days of discussions relating to the competition between cables and wireless, trams and buses, and motor transport versus railways much is expected from the newer systems. The rapid advance of the challenging competitors give rise to glowing and optimistic anticipations by enthusiastic supporters who foresee the doom of the old system. But the optimism is frequently overdone. It was so when the electricity supply companies challenged the gas companies. The use of gas for domestic purposes as well as for public xitility was seen to be ending. Electric light would replace gas in the homes and the gas companies would go out of business. . But we all know that those anticipations were not realised. The gas companies are still flourishing, and there are very few towns where gas supply has i been discontinued, although electricity supply has been introduced. So it is with long-distance cable communication. That system has not fallen, nor is it likely to fall, into disuse. Although wireless development has caused and is causing some anxiety amongst the shareholders of the cable companies, the keen attention by the managements of the companies to modernising their systems has enabled them to more than hold their own. 4YA FEATURES. The following is a resume of the programmes to be broadcast from 4YA during the coming week:— The service is to be broadcast from Knox Church to-morrow night. As the Dunedin bands are at the contest in Christchurch the usual band night on Tuesday will not take place. The vocal portion of the programme will be provided by Mr Alfred Walmsley (tenor), Miss Catherine Law (mezzo-soprano), Mr Reg. Richards (baritone), and Mr Cbas. Rowand (comedian). The instrumental music will be given by Mr 0. Judd (cornetist)

and Miss Rita Holmes (pianist). Miss Anita Wiukol and Mr J. B. M'Connell will be assisting. . On Thursday night Miss Winnie M'Peak (contralto) will sing, among other songs, O’Connor Morris’s charming little song, 1 1 Am Longing for the Spring.’ Miss Rita Holmes (soprano) has chosen three modern items. Mr F. M, Tuoliy, Mr E. G. Bond (bass), Miss Alice Wilson, F.T.C.L., and Mr Malcolm Robilliard will also ho heard. A feature of Thursday evening’s programme will be an address by Pastor W. I). More on ‘Unconscious Absurdities.’ , . , ~ , ~ Saturday night will be a _ night of opera. A group of Dunedin’s most successful singers will contribute various numbers from popular works. FACTS ABOUT CRYSTALS. If you go into a wireless shop and ask bravely for a crystal for your receiver the assistant will immediately ask you what kind you require (says a writer in ‘Modern Wireless). If you say “ What kind do you keep?’ ho will reel off a list of names as Jong as your arm. Some of these names you will recognise as those of mineral substances with which you are already acquainted, such as silicon, galena, copper pyrites, iron pyrites, etc. You will find, however, that many of them have such names as hertzite, lionite, perruanite, electrolyte, inax'konite, and what not. If you are not experienced in using crystals you can do worse than choose one of the crystals with a fancy name, for they are practically all speci-ally-treated galena, itself a very good rectifying substance. The special crystals are greatly superior to ordinary galena in one very important point—the number of sensitive spots to be found on their surface. If you take an ordinary cubical crystal of galena you_ will find that it is very bright and shiny and smooth. On the smooth surface you will bo able to find two or three exceedingly sensitive places, but they will take a good deal of finding. The specially-treated crystals, on the contrary, are sensitive on practically every part of their surface, If you examine such a crystal under the microscope, using a low power, you will see that the surface consists of a very large number of tiny crystals, and as each of these tiny crystals has one or two sensitive spots on its surface you can easily see why the whole substance must have a very large number of sensitive places. There is a great deal in the proper choice of the cat whisker. By the way, I wonder who was responsible for the peculiar term? I don’t see why the fine wire we use for making contact with the surface of a crystal should be called a cat whisker any more than a pig’s bristle or a dog’s hair. However, there it is. The name is stuck fast in wireless literature and cannot be removed oven by force. This cat whisker must be of metal, and it is advisable that the wire of which it is made should be as fine as possible. The end of the wire which touches the crystal surface must be kept quite bright, as such metals as copper and brass oxidise or have some other film deposited upon their surface from atmospheric action. If we are to retain our crystal detector at its maximum sensitiveness wo must occasionally keep this surface bright by clipping off the ends of the wire. If you take my advice you will buy a gold wire cat whisker. These are very cheap, as the gold is only 9 carat, and being fins very little of the material is used. This ca't whisker costs about 4d or 6d, and has the great advantage of keeping bright at its point_ for very long periods, if not indefinitely. A thick cat whisker will often miss the most sensitive points on the surface of the crystal, while a thin one will ferret out many which otherwise you would not notice., Thick whiskers can be improved by sharpening the point with a file. ‘ NEW ZEALAND RADIO.’ The second article dealing with a simple broadcast wave meter is contained in volume 4, No. 7, of ‘ New Zealand Radio,’ which has come to hand. Fading from 2YA is fully dealt with, and an article appears on 2FC’s Empire broadcast. Other matter covering a wide range _of radio topics is included in the issue. CORRESPONDENCE. D.F. (Waikouaiti).—Apparently there is a break in the wiring between the o.s. and Lt. negative. Make a close examination. An alternative solution is that the transformer windings have given out. “Accumulator” (Port Chalmers). — Yes, you could use the accumulator cells as you mention, but the ampere hour capacity would be only 30. “ L.C.J.” (Roslyn).—l am unable to answer your question as the matter has not yet been made public, to the be'st of my knowledge.