WIRELESS NEWS

Press, Volume LXVII, Issue 20412, 5 December 1931, Page 11

WIRELESS NEWS

By "MAX."

At a recent meeting of the American College of Surgeons at the WaldorfAstoria Hotel one of the most interesting of the medical apparatus exhibited was an outfit for bloodless operating. It consists »of a high'frequency oscillator, or in ordinary language, a transmitter, using a wave-length of about 1/0 metres.' An insulating handle and a fino wire are accessories, and when this is drawn across the flesh a bloodless incision is made. The voltage genf G hlgh fre quency side is I from 5000 to 35,000 volts. High ; frequency currents cannot give shocks to the system, though they can easily burn, and this is the principle. In one sense it reminds one of the oxyi acetylene blowpipe, which can cut through thick metal without damaging the nearby parts. This bloodless method is valuable, due to the fact that the heat seals the blood-vessels, and in cancer surgery is most important, for it prevents cancer cells which otherwise are freed by the operation from entering the blood stream and lodging in other organs of the body. ° " * • Television stations are steadily increasing in number in the United States of America, and now there is news that one will very shortly be erected in Canada. The power used will be equal to that of 3YA, but the wave-length will be in the television band used in America. • Some thirty television or "visual" transmitters are already licensed in the U.S.A., and the small band of frequencies wherein operating is permitted is already overcrowded. Frequencies of 80 million arc being assigned now, and this corresponds to a wavelength just below four metres. • • Fancy receiving one million letters in the course of twelve months. This was the mail of Father C. E. Coughlan, a radio preacher in a suburb of Detroit, after five years of regular Sunday afternoon broadcasts through station WJIt. The obscure church with a small .congregation has now grown to a nation-wide institution as a result of the radio personality of Father Ooughlan. It is considered that his Sunday audience of unseen listeners is well up in the millions.

On October 18th, some 100 stations scattered all over the United States combined in a special programme dealing with the unemployment problem. All the principal broadcast organisations co-operated, and President Hoover was to make a special speech. In technical details alone the. work must have been enormous, as one set of microphones only were to be used. 11l is pooling of tho country's radio resources into one unit for ono hour's broadcast is a hint of tho possibilities of using the 'chains of stations for . national emergency. • • What steps are the Government taking to ensure a smooth running of the programmes when tho present Broadcast Company passes over its control? At least one advisory committee held its last meeting a few days ago. and if the other parties also dissolve, something drastic will be necessary. It baa been the practice of the Broadcast Company to arrange programmes some five weeks ahead, this having been found essential. Commousense would make one think that everything to make for a smooth continuance of items has already been considered and provided for, but if all advisory committees are allowed to break up, it will take time to havo matters working properly on the first of next month. * * The oscillograph used by Mr 11. A. McLennan last week at tlio Radio Society's meeting is one of his own make nnd shows an inventive turn of mind. The princiole, roughly, is as follows: A beam of light is focused by a lens upon a minute mirror, and from this mirror it is reflected upon another at right angles to the first. From tho second mirror the pencil of light is thrown upon a ground-glass screen. Ono mirror oscillates -in one direction and the other vibrates in a direction at right angles. Old headphone units were rewound with heavier wire, through which alternating % currents wore passed. This caused an armature to vibrate in sympathy, and this in turn operates a mirror, which is delioately balanced and adjusted for the required effects. The actual frequencies of the currents employed for the demonstrations were not radio, but high audio, to represent a carrier wave. The modulating frequency was ordinary fifty cycle, but the combined results were comparatively the same as if a radio frequency were used for the carrier. It would be impossible to make an armature vibrate at very high frequencies.

An„.eliminator was employed to give the necessary voltages for the oscillating valve, and to keep the voltage steady with variations of current a neon lamp and a resistance across the eliminator were used very effectively. An ingenious method of suddenly discharging tho grid condenser was the use of a valve as a grid leak. This cansed ono of the mirrors to move quickly back to zero at the end of each half-cycle. # » One important use that Mr McLennan discovered that his oscillograph could bo put to was to prove that a transmitter for telephony was much more efficient when the valves were properly biased. The ratio of output to input is considerably greater when this point receives correct attention. « # It was stated recently that the superheterodyne receiver is coming back into favour. Several years a«o, when the neutrodyne system was developed, multi-stages of straight radio frequency amplication became popular with manufacturers. Matching oi coils and condensers and ganging ot th© lattei gradually eliminated the multiplicity of controls. The older type of super was a selective one, but the main fault was lack of quality and mainly for this reason the straight radio set sold better, though unselective. # » Now it is much easier to stabilise the lower radio frequencies, especially when down to about 100,000 cycles. Oscillation difficulties are comparative-

Notes From Far and Neap

ly easily overcome. A frequency tor the intermediate amplifier of this order is usually employed. A still lower frequency is too neat- that of the lonS wave stations, and also of parasitic electrical currents. A higher ratio of amplification fan also be permitted lor each valve used in the intermediate frequency portion. « • The difficulty of poor quality has been overcome, and the addition of a series tuned acceptor circuit in the antenna will by-pass a strong local whose wavelength is close to a distant station which is hem?: received. Ganging, and matched coils and condensers do away with one control. The super has the input tuned to the required frequency, and a separate oscillator i s tuned to frequency above or below the wanted one by a number of cycles corresponding to the intermediate frequency amplifier. This difference can be kept constant over the whole ranee of the receiver bv correct design of the tuned circuits of the first detector and the oscillator, plus the eanicd control method. That is whv n modern superbet has only one tunimr control. If a staere of radio precedes the first detector, it is ganged also.

BROADCASTING.

I TO-DAY'S PROGRAMMES. | 3YA, CHRIST CHURCH (DBO Kilocycles.) 3 p.m.: Gramophone recital. 4.30: Sports results. 5.0: Children's hour. 6.0: Dinner music session (Columbia). 7.0: News and reportß. 8.0: Chimes. Tvelay from the Civic Theatre of concluding sing. The singing will be led by Mr Owen Pritehard, with whom will bo associated others who have acted ns eonff leaders during the season. 10.0: Dance music (I'arlnphono). SZC, CHRISTCHURCH. If a.m.: The l.ousewife's session, conducted l>y Millicent Jennings—Stories and Tieadines, end musical prom-ammo. 11.30-12.30: Recorded musical programme arranged by Mi3s Frances Ilaruertnn. 27A, WELLINGTON (720 Kilocycles.) 3 p.m.: Chimes. Selected gramophone recordings. 3.30 and 4.30: Sporting results. 5.0: Children's hour, conducted by Aunt Molly. 0.0: Dinner music session (Columbia). 7.0: News, reports and sports results. 8.0: Chimes. Relay from the Concert Chamber, Town Ilall, of Concert by the Wellington Apollo Singers. Choral—Apollo Singers, (a) "Awake! Awake!" (Morning; Song) (Cadman, arr. Ross Hilton); (b) "My Bonny Lass, She Smileth" (Morley, arr. Keighloy); (c) "The Sword of Ferrnra" (Bullard). Soprano—Miss Teresa McEnroe, "The Jcwol Song" (Gounod). Choral—Apollo Singers, (a) "Summer Night" (Brocckx): (b) "Shenandoah" (Bartholomew). 'Cello — Mr George Ellwood, (a) "Minuetto" (Becker): (b) "Vito." Choral—Apollo Singers, (a) "Yonder! Yonder!" Soloist. Miss Toresa McEnrqe; (b) "Ring Out, Wild Bells" (Fletcher). Weather report and station notices. Choral—Apollo Singers, (a) 'Follow the Gleam" (A.vlward, arr. Gaines); (b) "O Peaceful Night" (German). Soprano —Miss Teresa McEnrM, (a) "At the 'Mi<l Hour of Night" (Cowen); <b) "Song of the Open" (La Forge). Choral—Apollo Singers, "Pilgrims' Chorus" (from "T»nnhau««r"). •Cello—Mr George F.llwood. (a) "Abendlied" (Schumann); (b) "Gultarre" (Moskowski). Choral—Apollo Singers, (a) "The Musical Trust" (Clokeyl : piano duct br F.rnest. Jenner and Wm. Billington, (h) "The Hunter in His Career" (Grainger). 10.0 (appro*.): Dance programme from the studio (Columbia). 11.0; Sporting summary. SUNDAY. 3YA, CHBIBTCHTJECH. 8 p.m.: Gramophone recital. 5.30: Children's song service by children of tho Methodist Sunday Schools. 6.15; Chimes. 6.30; Selected recordings. 7.0: Relay of evening service from Durham street Methodist Church. Preacher: Rev. M. A. Rugby Pratt. Organist: Mr Allan Welbrock, L.A.B. Choir condu<;tur, Mr C. N. Bargenson. 7.45: Selected recordings. 8.15: Overture — Berlin State Opera Orchestra, "La Belle Helene." 8.23: Mezzo-contralto—Mrs Anita Ledsham, (a) "Tho Linnet is Tuuing Her Flute" (Bauer); (b) "Habanera" (Bizet). 8.29: Flute—Mr A. K. Hutton, with Studio Octet, "Aria" (Lemmone). 8.34: Tenor — Mr David McGill, with Octet accompaniment. "Flower Song" (from "Carmon") (Bizet). 8.38: Piano—Miss Maisie Ottey, (a) "Lea Adieux" (Dussek); (b) "Colonial Song" (Grainger). 8.15: Soprano—Miss Cicely Audibert, (a) "The Call of Spring" (Strauss); (b) "Mia Piceirella" (Gomez). 8.52: Male rhoir—Erk's Male Chorus, "The Linden Tree" (Schubert-Strange). 8.50: Orchestral —Studio Octet (Conductor, Harold Beck), "L'lmpreKsario" Overture (Mozart). 9.1: Evening weather forecast and station notices. 9.3 : Orchestral —Orchestra of Opera Paris, "Marche Heroique." 9.'J: Mezzo-contralto—Mrs Anita I.edeham, with Octet accompaniment, (a) "Four By the Clock" (MaUinson) ; (b) "The Hills of Donegal." 9.15: Flute—Mr A. E. Hutton, with Studio Octet, "Loiu du Bal" (Fillet). 9.18: Tenor—Mr David McOill, (a) "B Lnce Van Le Stella" (Puccini); (b) Tho White Dove" (Lehar). 9.24: Piano —Mins Mnirie Ottey. "The Island Spell" (Ireland). 9.27: Orchestral—Studio Octet, "Melodies of Grieg" (arr. Beck). 9.36: SopranoMiss Cicely Audibert. (a) "Lovers in the Lane" (Lehmann); (b) "The Butterfly is in Love with the Rose" (Cox). 9.40: Orchestral—Studio Octet, "Folk Song nnd Fiddle Dance" (Fletcher), 9.49: Male choir — London Male Voice Octet., "The Keys of Heaven." 9.53: Violin—Jascha Heifetz, (a) "Jota" (de Falla) ; (b) "Puck." 9.56: Orche.stral—Studio Octet; "Monsieur Beaucaire Incidental Music."

3ZC, CHRIST CHURCH. 10-11.30: Morning session. 6-7 p.m.: Evening concert on short wave. 8.10 p.m.: Evening broadcast conceit. Kocorded programmes arranged by Miss I?"ranees Hamertoii. 2YA, WELLINGTON. 3 P;"V : Selectod gramophone recordings. 6.0: Children's song service, conducted by Uncle George, assisted bv the children's choir from tho Cambridge Terrace Oongrega-, tional Church. 7.0: Relay of Evening Service from the Terrace Congregational Church. Preacher: Rev. H. W, Newell, Organist and Choirmaster: Mr Harry Brusey. 8.«0_ (apprnx.): Concert by the Wellington Municipal Tramways Band, and 2YA artists. March—The Band, "'Machine Gun Guards" (Marechal); "Celebrated Largo in G" (Ilandel) ; Selection, "Reminiscences of Tschaiknwsky." Baritone—Mr Keith Grant, (a) "The Linden Tree": (b) "Tho Inquirer"; (c) "Impatience" (Schubert). Soprano—Miss Joyce Woodward, "Spring, the Fiddler" (Baumer). Waltz—The Band, "Waves of the Danube" (Ivanovici). Plexatone solo and Brown, "When Your Hair Has Turned to Silver." (Campbell). Weather report and station notices. Tenor—Mr Egerton Pegg, (a) "Come Tnto the Garden, Maud" (Balfe): (b) "Spirto Gentil" (Donisctti). Story— Miss Mary Cooley, "The I>sdy and the Tiger" (Stockton). Potpourri—The Band, "Musical Memories" (Trtnchard). Cornet—Bandmaster Stevenson, with Band, "Alpine F.clioes." Baritone—Mr Keith Grant, .(a) "Adelaide" (Beethoven); (b) "Thi? Great Awakening" (Kramer). f-'oprano—Miss Joyce Woodward, -(a) "Love, the Jester" (Phillips); (b) "Youth" (McGeogb). Tenor—Mr Egerton Peg?, fa) "The Flower Song" (from "Carmen") (Bizet); (b) "Goodnight. BelovedV' VBa'f<?>. March —The Band, "The Vanished Army" (Alford); "Hallelujah Chorus" (Handel).,