RADIO REVIEW

Evening Star, Issue 19616, 23 July 1927, Page 16

RADIO REVIEW

[By fiEsnr.]

Any newsy item will be welcomed for this column. ALTERNATING CURRENT VALVE. In England a valve has been produced in which the" filament has been replaced by an active materia! heated by means of alternating current. In it the nlato and grid arc of the usual form, but the filament is really a very thin metal sheath treated with the same' material employed on the filaments of dull emitter valves. The metal sheath is heated by a special beating unit, through which alternating current is passed from a small transformer connected to the ordinary mains.

■ The elaborate filament system is employed to separate entirely the alternating current filament heating circuit from the receiver. For the operation of the receiver return wires which ordinarily go to valvo filaments are- connected with the heated sheath, and the alternating current system is thus separated completely from tho receiver circuit. This should effectively prevent the introduction of a hum or ripple into tho introduced into tho loud spcalcor, If tho now valve mil fulfil the claims made for it, there will be available an easy means of constructing a receiving set to operate from tho alternating current mains. Of course, a plate voltage source is still necessary with tho new valve.

The new valvo shows a divergence between the methods adopted by British and American manufacturers in applying alternating current service to wireless receiving sets. The American system depends on the use of special circuits associated with ordinary valves, but the British, apparatus will employ a valvo specially intended for alternating current operation. POWER LEAKS. Power leaks, which aro among tho most annoying noises radio enthusiasts have to contend with, aro often traceable to burnt-out or faulty street lights. If listeners-in would ring tho testroom of the electrical power station in Cumberland street whenever they notice a faulty light the matter would at once be attended to, and a probable, cause of annoyance rectified.

HERE AND THERE. At a well-attended meeting of listeners recently in Wanganui it was decided to form a listeners league there to act with similar organisations in seeking to improve radio broadcasting in the dominion. Undo Jack, at 3YA, introduced a novelty a few nights ago when he invited ex-Petty Officer Cobley, late of the Royal Navy, to tell the children about a dav with the Navy. It is alleged that radio broadcasting has the effect of shortening the life of popular songs. Evidently broadcasting serves some useful purpose. To develop dexterity with tho soldering bolt pick up -odd pieces of wire and metal and try soldering them together. A radio set lias been installed at Caroline Bay (Timaru), and when tho Canterbury team goes on tour descriptions of tho games will bo received at the Bay. KPO is now completing the installation of a new 25,000 dollar studio pipe organ, which will probably bo the largest radio studio organ in America. The console has three keyboards. There will bo eighteen sets of pipes with pipes in each set. CUTTING OUT 2YA . The difficulty of cutting out 2YA by Wellington listeners should not ha very serious for a reasonably good receiver. A Wellington paper states that a neutrodyne receiver about two miles from i tho station was able to cut out 2YA i entirely before the dial bad reached the setting of 3YA. During the Ranfurly Shield transmission a suporhetrodyne receiver at Oriental Bay was successful in bringing in 2FC Sydney, which is only twenty-two metres away from 2YA. A CHRISTCHURCH BALLOT. Recently the Christchurch 1 Sun * arranged a ballot for the radio listeners for the purpose of ascertaining their I choice of broadcast fare. The results | were:— 1 Band and orchestral music ... 408 Instrumental items ..., 439 Theatrical and choral 314 1 Vocal solos ... ... 293 | Lecturet'tes 283 Snorting and laces 191 j News 142 | In tho Melbourne plebiscite ,band music held the top place as is tho case with the Christchurch ballot. Evidently Melbourne and Christchurch listeners’ tastes are tho same.

HOBART ON INCREASED POWER. 7ZL, Hobart has been working for some time on increased power, 3,000 watts now being used. This station can now bo heard in New Zealand by most amateurs with efficient receivers. The tuning of the station, which transmits on 535 metres, is exceptionally sharp and steady. In this respect it sets an example worthy of emulation by many of the leading Australian stations. Up to the present this station has been erected and managed on the capital of the company, hut there is a reserve fund from receivers’ licenses in Tasmania. It is estimated the revenue of this station will be less than £3,ooo'a year, owing to tUo small population in Tasmania, so it will be interesting to watch the programme developments on such a meagre income. Up to the present the programmes have been remarkably good, considering the financial difficulties the company has had to surmount. HOLLAND LAST SUNDAY. For tho benefit of Australian and New Zealand listeners PCJJ, Holland, was on the air last Sunday afternoon with a special programme. Tho wavelength used was 14.6 metros. Piano, organ, and orchestral selections came in as clear as a bell, and vocal solos were well received. At tho close of the programme ‘God Save tho King’ was played about half a dozen times, evidently a gramophone record. Tho imnounccr at tho station said that, as this was a special test, the people at the station had to work very early in tho morning, tho time being, roughly, about 4 a.m. WGY’s POWER VALVE. WGY, in Schenectady, uses the largest power valve in its transmitting station that has over been installed in a station in tho United States. It is rated at 100 kilowatts, and, in its

water jacket, stands 71ft high and weighs about 1001 b. The filament of this tremendous valve is Bft in length, and is approximately the thickness, of No. 22-gnu go wire, containing 750,000 times as much tungsten as the ordinary small dull emitter valve. A heavy spring, similar to that used on doors, is required to keep this filament under tension, and prevent it twisting. The loads to tho lilament are as largo as a lead, pencil, with the terminals similar to those used on largo power switchboards.

The physical dimensions of the valve, of course, while interesting, give little indication of its power. A better idea of this is gained by the fact that eight 20-kilowatt valves that WGY had previously boon using have been displaced by this valve. Up till then an output of 50 kilowatts had been “ superpower,” but now- it is considered that a power of 500 kilowatts, or oven more, will ho possible. This can ho compared w'ith 2BL’s present power, and it may ho assumed that listeners then would have just reason for complaints concerning interference.

Tho 100-kilowatt valve is used as a radio frequency amplifier, fulfilling lithe transmitter a function comparable with tho ordinary radio stages in receiving sets. In the receiver a very weak radio'frequency signal is picked up by the aerial and amplified by the radio valves, whereas tho valve in the transmitter amplifies tho radio frequency _ signals preparatory to their being imposed upon tho aerial. The valve has a pressure _ gauge, as the hardness, or degree of vacuum in the valve, is naturally important. The water jacket, of course, is to' keep the valve at an even temperature, AROUND THE AUSTRALIANS. NEWS FROM THE OTHER SIDE. During tho year ended Juno 50 the number of radio licenses in Australia increased by 97,079, making a total of 215,139. Victoria heads the list with 118,965. Nearly a solid hour of laughs offered by more than 100 persons were recently broadcast from an American station. Each contestant was allowed thirty seconds to charm tho “ fans,” and the judges picked tho winners from receivers in their homes. OLO’s laughing competition will soon bo arranged. Commander Laurinson Barnett, R.N. (on the Royal Navy retired list) is bringing the sea to the air through 3AR.

Some people abhor tho limelight. Such a person is “ Percy,” of 4QG bed-time-story fame. Many children have written to tho Sandman at the station requesting information about “ Percy,” but that person does not wish to have his identity known. Even adults have written inquiring about “ Percy,” which says a good deal for the ventriloquil powers of the Sandman. It is hoped that few children will ever discover who “ Percy ” really is. This paragraph clumsily attempts to hide his identity, because for the youngsters, at least, a good deal of tho interest would bo lost if it was known who he was.

Radio is of tremendous value to the police, as was shown in Sydney recently, A young woman was murdered at Petersham, a Sydney suburb, and suspicion foil on a certain man. Apart from the usual police activities the wireless patrol traversed miles.a day in search of him. The patrol made <T thorough search of all the houses for miles around, continually receiving fresh information by wireless from headquarters. Eventually an arrest was made at Bathurst, which is 140 miles from Sydney. 3LO is arranging another competition, this time a public-speaking test. The conditions will shortly be announced. The latest feature of tho women’s session at 2BL is a weekly talk on ‘ Dental Hygiene ’ by a representative of tho Dental Board.

Tho Four Waifs, the popular male quartet, will again delight listeners to 2FO next Saturday night.' On the same night Embaldo Russo (Italian baritone') and Linda Bedford (mezzosoprano) will return to tho station. Lawrence Macaulay, tiro noted Scotch bass, recently landed in Sydney, and he has been booked by 2FC. Ho will make bis first appearance on Thursday night next.

Two classes of enthusiasts listen to tho rebroadcasts of European stations. They are those who rise early in the morning and those who hoar tho programmes in bed. Writing to 2BL, quite a number say they have heard the rebroadcasts in bed, and an equal proportion mention they sat up in tho cold. Quito a number simply listened, and not a few dropped off to sleep during the programmes. Madam Mary Conly (international celebrity), Mr John Hobbs (baritone), and Mr Edward Beachcroft (tenor) arc at present on tho 3AR programmes. 2FC has received a letter from Philadelphia, U.S.A., in which tho writer says that on Saturday, May 7, he clearly heard the station dance baud playing tho fox trot ‘ Oil the Riveira.’ A reference to tho station’s logs showed that the item was broadcast at 9.55 on that night. / Few Australian vocalists possess such a reputation for versatility as Colin Crane, tho well-known J. C. Williamson Theatres baritone, who has just been engaged by 3LO.

_ An Australian radio man now travelling in America writes to 2FC, commenting on tho very extensive use of broadcasting stations by tho farms of the United States. Since July, 1925.' tho number of radio sots used on farms had increased from 553,008 to 1,252,216. Soon listeners to SCL, Adelaide, will be able to hear running descriptions of tho principal sporting events in Victoria direct from the course. Arrangements have been made with 3AR, Melbourne, whereby SCL will make uso of the former station’s broadcasts.

The Magill Silver Band will soon bo heard from SCL for a season. Tin's was tho band engaged to play at Government House during a garden party held in honor of tho Duko and Duehess of York on their recent visit there. HOWLING. There is ono beautiful person belonging to tho Oswald brigade in Dunedin. Night after night ho sets up a cruel howl right on top of Christchurch, and all other listeners in Dunedin might just as well shut down on tho northern station for all they get. The howler, who is either doing it on purpose or who knows nothing at all about his set, lias been hoard in all parts of Dunedin from tho north end to- tho south end. Ho seems to favor 2BL for his fare sometimes, for ho continually outs across that station, eventually settling down on top of tho Sydney man. If the howler knows nothing about his, sot ho should get someone who does to sot things right; but if he is oscillating on purpose ho has obviously a perverted souse of humor.

SIGNAL STRENGTH MEASURE- ■ MENTS OF 3LO. I am in receipt of a booklet from 3LO on_ tho signal strength measurements of 3LO. Melbourne. The booklet gives a record of tho results of an investigation, carried out at the natural philosophy laboratory of the University of Melbourne, of the signal strength of a broadcasting station, and discusses what strength is desirable in'such a signal. STEPHANIE DESTE’S DRAMATIC ART. [By Bixmv Tea, from 3LO.] Those fortunate theatregoers who know Stephanie Desto as the wonderful dancer in ‘ Ross Mario 1 could hardly have anticipated that she can apply Her terpsichoreau abilities even to mere words. Yet her frequent appearances before the microphone at 3LO Melbourne are an ever fresh delight to the great

audience that hears but cannot sec her. From her melodious mouth the words dance as nimbly ns she herself; and it is all done with a grace, a daintiness, a fire, a delicacy that thrills all who listen. On a recent Sunday night this mistress of words showed a ran to of expression from the whimsical _ childishness of ‘ Little Orphant Annie ’ right up to the tense tragedy of ‘Edinburgh After Plodden,’ and enthralled all who heard it. There were an extra fortunate few who also saw her reciting with uplifted_ chin, eyes closed, and fingers tightly interlaced, poising now on one foot, then on the other, and finally in the excess of her passion flinging aside her heavy' fur cloak as a spirit dispossesses itself of this mortal body, and soaring to the heights of tragedy until all who saw shook with her last long moan. 3LO Melbourne has conferred a great treat on its widespread audience by broadcasting Miss Stephanie Dcste’s dramatic art.

SHIELDING THE RECEIVER. For a. very considerable time back shielding has been used with wireless receivers, particularly on commercial installations. Lately more and more broadcast sets are being shielded thoroughly. The object is to reduce body capacity and interaction effects lietween radio frequency stages of amplification. A wireless set which has several stages of high-frequency amplification is generally specially designed to avoid interaction between tho radio frequency transformers as much as possible. It will bo noticed that a number of neutrodyno and super-heterodyne receivers have their transformers set at a particular angle. This is done to avoid interaction. _ A better result can be had by placing a grounded metal plate between the transformers. This has the effect of preventing the electro-mag-netic fields of the coils extending as far as the adjacent coils, and inducing stray amd unwanted currents in them. When a wireless set is improperly designed and interaction between the transformers is bad, the set will break into oscillation, and so introduce parasitic noises as well ns restrict tho degree of amplification obtained. Body capacity is one of the most noticeable effects of bad screening. When the band of the operator is brought up to the set to alter a dial or adjust something the set will immediately eithejybreak into oscillation or alter its tuning sufficiently to howl. If tho panel is made of sheet metal, and this is connected to earth, tho movement of the operator’s hand, will not have any effect on tho operation of the set. CORRESPONDENCE. “Anxious” (Mosgiel).—lt is not your set that is fading, but the stations you receive. Wellington is much louder than Christchurch; perhaps you have not tuned him in properly. Any valve of tho 201 A type should give good results in your receiver. Most A class batteries, you will find, will give good reception. Tho power valve you speak of is used more or less for bringing in the stations with a purer tone. In future please sign your name and address to any correspondence, otherwise it will not be answered in this column.