RADIO RECORD

Greymouth Evening Star, 9 July 1931, Page 8

RADIO RECORD

NOTES FOg HSTENERS-JN

(By Mk A A

"Reception”)

AUTOMATIC GRID BIAS Some people have raised a question regarding automatic grid bias, uajs S. H. Reyner, in “Amateur Wireless. They suggest that the design of the resistance to give the appropriate gild bias with a given anode current is a fallacy, because the anode current is varying the whole time. On the face of it. this looks quite correct. If we apply a signal to the grid which increases the anode cturent, then the grid bias will increase and vice versa. A large condenser should be connected across the gridbias resistance. Due to the voltage drop across this, the condenser is charged to a certain steady voltage corresponding to the grid bias reqmrCd in order that .this condenser shall alter its voltage, it must either charge or discharge a little, and this takes tim£. The larger the condenser, the longer the time occupied in changing its condition. Since the variations in anode current are mostly occurring hundreds and even thousands of times per second, the condenser ignores the variation. The only case where we have any action of this sort taking place is at the very low frequencies or on sudden transient terms. Here a little thought will show that the action is to our advantage rather than the reverse. It we get a sudden very heavy passage in the bass which tends to overload the amplifier, the grid bias will automatically increase at the peak, avoiding distortion to some extent. This is noticeable in actual practice with the amplifier under consideration. It is found possible to apply signals which are known to be over-loading the amplifier without producing unpleasant. distortion.

LIFE OF A RADIO STAR It used to be thought that “movie stars had the shortest careers of all artistes, but now it seems that those of broadcast celebrities are even briefer. says a writer in “Amateur Wireless.” That, anyhow, is the experience of American broadcasting authorities. A remarkable instance is the case of Amos n’ Andy, who a year ago were so nopular that it was seriously said of them that they were costing business and industry millions of dollars a year, since nothing could tear people away from their loudspeakers when this witty pair was before the microphone. Amos n’ Andy are probably funnier than they have ever been. I have picked them up direct from some of the N.B.C.’s chain of stations several times. But America is no longer greatly amused by them. Honestly. I don t wonder, for both they and their audiences are becoming a little stale, for when American stations do lind a good turn they certainly do work it hard. Looking over the N.B.C. programmes for the current, week. I lind that they are appearing every night except Sunday at 7 and 11.30 p.m. (Eastern standard time, of couise), and they have been doing so lor months and months. The National Broadcasting Company’s chain includes a huge number of stations. On most nights they have three turns, there being an additional one at 11 p.m., though, of course, some stations take one of the late turns and some the other. < Tlie result is that the unfortunate Amos n’ Andy have their turn broadcast eighteen times a week to an audience of millions of people and always this is the most unkindest cut of all at the same hour. Can you wonder that neople ceased to giggle over their quips in time? The American authorities are, loi some queer reason, extraordinarily keen on running artistes to death in this way. WLW. for example, has a very witty pair who choose to call themselves Salt and Peanuts. These unfortunate people have to appear before W.L.W’s microphone eleven times a week.

MARCONI PROPHESIES “At the present time, we are in an experimental stage, but the expeiiments of the shortwave system, which my assistants and I are carrying out for the Research Organisation of the Italian Government —and about which I. may have something to say in a few months’ time —are altering values rapidly,” said the Marchese Marconi in an interview recently in England. “To begin with, wireless will-become much cheaper and of far more general use. It may be said to be almost universal now, but in ten years time it will have made the world very small. People will telephone to Australia as easily as they do now to the Crystal Palace. I do not want to be too definite, but there is a great chance that individual subscribers will have wireless telephones in theii houses in the next decade. “Then in ten years television should have developed and arrived as a practical aid to entertainment; I doubt if it will be used for much else than for that.”

PORTABLE SETS There is a very simple way in which any portable comprising a self-contain-ed frame aerial may be used with an ordinary aerial, without interfiling with the internal arrangement of the receiver at all, says Dr. .1. H. T. Roberts, in “Popular Wireless.” This arrangement consists in effect of a loose-coupling between the aerialearth system and the frame aerial in the portable receiver. If vou bring the lead-in from the ordinary line aerial (whether outdooi or indoor aerial) to the portal) e and wind a number of turns of fairly tine wire around the cabinet of the portable (preferably in the immediate vicinity of the frame aerial inside), continuing the aerial lead then to eaith, you will have in effect two coils, one in the aerial-earth circuit and the other, the frame aerial, in the receiver circuit, these two coils being loosecoupled together. In fact, the arrangement may be described as a loosecoupled semi-aperiodic outdoor aerial arrangement. It is practically certain that a considerable increase in the sensitivity and range of the receiver will be obtained in this simple way, although the actual number of turns of wire must be found by experiment. As a general rule you can take it that more turns in the aerial coil will feive more powerful reception within limits, of course —while on the other hand fewer turns will tend to preserve selectivity.

TOTTED PROGRAMMES The use of records as parts of broadcast programmes dates back, to the beginning of broadcasting, but a somewhat novel type of record is now being introduced which is expressly designed for broadcasting purposes, says Dr. J. 11. T. Roberts, in “Popular Wireless.” This record, which is of large diameter, so as to carry a much greater amount of recorded matter, is specially made up by re-recording (or “duping” as it is called) existing records, thus combining several records into one.

In this way it is easy to record an entire broadcasting programme upon a small number of records so that the whole programme can then be forwarded to different broadcasting stations in a sort of “potted” form. This method is rapidly gaming ground in the United States, where there are an enormous number of individual broadcasting stations scattered throughout the country, some of which are comparatively small stations unable to undertake the expense of maintaining programmes of artistes. A central organisation makes up the recorded programmes—for all the world like making up the menu of a dinner, or a set of lantern slides for a lecture-—and compiles an expensive library of complete programmes, which can be supplied to stations at a fraction of the cost of maintaining programmes of living artistes. Any particular programme is only dstributed to stations fairly widely separated, so there is no likelihood of two near-by stations both sending out programmes No. 1 at the same time. The records are officially referred to as “electrical transcriptions.” and the system has already been adopted by a number of stations in the United States.

MICROPHONE VALVES It is rather curious that after having made so much antimicrophonic valve holderJ*we should now be returning very largely to the rigid type, writes Dr. J. H. T. Roberts in “Popular Wireless.” It is not so long ago that nobody would have thought of constructing a receiver without using springy valve-holders. The change, of course, has been brought about by the very great improvements in the construction and robustness of the electrode systems in present-day valves, which have largely rendered springy valve-holders unnecessary.

As a matter of fact, in some types of sprung holders the amount of free, play allowed was excessive, and if the receiver were suddenly shifted about there was considerable danger of tire valves themselves (if placed fairly close together) striking each other, with the possibility of broken filaments or even broken bulbs.

Again, sometimes the soldered connections to the sockets would become broken oft’ and many an experimenter has been a long time looking over the usual sources of trouble before discovering that this was the real cause. Provided the valve itself is antimicrophonic, it, is in many ways. an advantage to use an ordinary rigid holder. TO-DAY’S PROGRAMME IYA, AUCKLAND (900 Kilocycles). 5.0: Children’s session; 6.0: Dinner music session; 7.0: News and market reports; 7.40: Talk —“Foundation Garments—-Corsets.” Under the auspices of the New Zealand Manufacturers’ Association; 8.0: Studio concert by the Auckland Society of Musicians. Trio —Misses Helen Gray, Jean Clarkson and Dorothea Mulgan, (a) “Ballet Music—Rosamund”; (b) “Serenade”; 8.9: Soprano—Miss Patricia McLeod, (a.) “Oh, Had I Jubal’s Lyre”; (b) “Rose Softly Blooming”; 8.16: Piano —Mr Owen Jensen, two etudes, (a) “E Majoi, Op. 10, No. 3”; (b) “E Minor, Op. 25, No. 5; “Rhapsodic* in E Flat, Op. 119”; 8.27: Baritone —Mr A. ' B. Thompson, Songs fioin Tennyson s Poem. “Maud,” set to music by Arthur Somervell: (a) “I Hate the Dreadful Hollow”; (b) “She Came to the Village Church”; (c) “Birds in the High Hall Garden”; (d) “Go Not, Happy Day”; iej “Come into the Garden Maud"; 8.36: Violin—Miss Helen Gray, (a) “Romance”; (b) “Spanish Dance”; 8.44: Soprano. Miss Patricia McLeod, (a) “Two Gypsy Melodies”; “Slumber Song”; 8.51: Concerto arranged for two pianos—Miss Eva W. Hood and Mrs Ludbrook, “First. Movement— Allegro Motto Moderate”: 9.1: Evening weather forecast; 9.3: ’Cello—Miss Jean Clarkson, (a) “Andantino”; (b) “Allegro Con Brio”; 9.11: Baritone—Mr A? B. Thompson, further songs from Tennvson's poem, “Maud” (a) “Dead, Long Dead”; (bi “Oh. that it were Possible”; (c) “My Life Has Crept so Long”; 9.19: Piano duo —Miss Eva \V. Hood and Mrs Ludbrook. “Wedding Cake Caprice Valse,” Op. 76; 9.24: Trio—Misses Helen Gray, Jean Clarkson, and Dorothea Mulgan, “Allegro Vivace from Trio Op. 70, No. 1”; 9.31: Programme of dance music. 2YA, WELLINGTON (720 Kilocycles) 6.0: Dinner music session; 7.0: News session: 7.40: Lecturette —Miss Inez Connop, “Dancing in Relation to Health”: 8.0: Studio concert by the Wellington Artillery Band (Conductor Capt. T. E. Herd) and 2YA artists; 8.10: Bass—Mr. R. J. G. Madigan, (a) “Ochone, Bridget O’Flynn”;, (b) “Katie McGee”; 815: Vibraphone— Miss Joyce Morgan, (a) “My Old Kentucky Home”; (b) “Old Black Joe ; 8.19: Cornet duet —Sergts. Bowman and Johnston, “Two Comrades”; 8.24: Contralto —Miss • Mabel Dyer, (a) “The Sweetest Flower that Grows"; (b) “That’s All”; 8.29: One-act mystery play —“The Real Q (Teriell and Stechhan). Characters: The Doctor, Mr. Kenneth Aitken: The Detective, Mr. Hedley Aitken; The Thief, Mr. Norman Aitken. Scene: Dr. Cornish’s Oflice, New York; 8.48; Band. "Gems from Sullivan’s Operas”; 9.0: Evening weather forecast; Accordion—Jean Vaissade, (a) “Coucous”; (b) “The Secret of a Night"; 9.8: Vocal duet —Miss Mabel Dyer, ami Mr. Edgar Swain, “At Dawning”; Contralto —Miss Mabel Dyer, “Through the Sunrise”; 9.14: Vibraphone —Miss Joyce Morgan, (a) “Carry Me Back”; (b) “Old Folks at Home”; 9.18: Bass—Mr. R. J. G. Madigan, “The Bosun’s Advice”; 9.22: Waltz—The Band, “Red Poppies”; Cornet solo —Sergt. W. H. Bowman, “Beyond the Dawn”; 9.31: Tenor—

Mr. Edgar Swain (a) “Dolorosa”; (b) “The Fuschia Tree”; 9.37: The Band, “Naworth Castle”; “Hibernian Melodies”: 9.50: Male choir—Don Cossacks. (a) "The Red Sarafan”; (b) "March Prince Cleg"; 9.56: The Band “Frisky Sambo.” 3YA.. CHCII. (980 Kilocycles) 5.0: Children’s hour: 6.0: Dinner music session; 7.0: News session; 7.30: Talk—Dr. I. W. Weston, Lincoln Agricultural College, “Farm Accounting Associations”; 8.0: Berlin State Opera Orchestra, “Barber of Seville”; 8.4: Quartets—Melodious Quartet. Negro Spirituals, (a) “Nobody Knows do Trouble"; (b) "Deep River”; Soprano—Miss Frances Hamerton, with orchestral accompaniment “Waltz Song"; 8.11: Studio Octet. “Fidelio” Overture; 8.17: Bass-baritone—Mr. T. D. Williams, “I Fear No Foe”; 8.42: Sonrano and tenor —Dolce Duo, “Swing Song”: 8.-17: Violin with orchestra —Soloist, Miss Irene Morris, “Concerto in A Minor”: 5.57: TenorMr. Russell Sumner with orchestral accompaniment, (a) “Serenade": (b) “Pleading”; 9.1: Weather foipcast; 9.3: Flute—Mr. A. E. Hutton. “Loin du Bal”: 9.6: Soprano—Miss [•’ranees Hamerton, with orchestral accompaniment, “My Harp is on the Willow Tree”; Melodious Quartet —“Sweet and Low”; Mezzo-contralto —Miss Millicent Jennings, with orchestral ac cempaniment, “The Peace of the Valley”; 9.17: Selection —Studio Octet, “Cavalleria Rusticana”; 9.30: Dance music programme. 4YA, DUNEDIN (650 Kilocycles) SILENT DAY.