THE WIRELESS WORLD

Otago Daily Times, Issue 22911, 19 June 1936, Page 21

THE WIRELESS WORLD

NEWS AND NOTES

By Maona Vox,

Items of local interest are invited by "Magna Vox” for publication in this column. It is necessary that such matter should reach this office by Tuesday of each week Tor insertion on the following Friday. 2BL, Sydney.—74o K.C., 405 metres. 2FC. Sydney.—6lo K.C., 492 metres 3AR, Melbourne.—63o K.C., 478 metres. 3LO, Melbourne.—77o K.C., 390 meares. SCL, Adelaide. —730 K.C., 411 metres. 4QG, Brisbane.—Boo K.C.. 311 metres. IYA, Auckland—6so K.C., 461.3 metres. 2YA, Wellington.—s7o K.C., 526 metres. 3YA, Christchurch.—72o K.C.. 416.4 metres. 4YA, Dunedin.—79o K.C., 379.5 metres., 4YO, Dunedin. —1140 K.C., 261 metres. ANSWERS TO CORRESPONDENTS. G. D. M'K., Dunedin.—A serviceman would do the job for you at a comparatively email cost. Such advice as I can give within reason, I will gladly tender, but it could hardly be expected that I should undertake the duties of a serviceman. " Aerial,” Wyndham.—lf the set docs ■not still behave normally when you are using the earth lead as an aerial, the fault certainly lies in the set, and is probably due to a poor connection somewhere, or a faulty by-pass condenser. The normal behaviour of the set, however, indicates a poor connection in the aerial system. Check over the lightning arrestor and the lead-in strip or tube, if you are using one. Also clean the insulators and carefully examine the flat top and lead-in for breaks. You should also look out for branches, etc., which, in a breeze, might sway and make intermittent contact with the flat top or leadin. A, W. F., Tomahawk—The on/olf switch in your set operates only in the filament circuit, and it is thus quite in order for the plate and screen voltages to be present on the valves when the set is switched off. There is no “B ” current passing, and hence there is no battery waste. Apparently all that is wrong with your set is that it needs a thorough re-ajigning on all bands, using a calibrated ah-wave oscillator. If you have this done, you should notice a distinct improvement in results. ■ “ Phones,” Ngapara.—To attach headphones to your set, connect one side of a .05 mfd. fixed condenser to the plate ot each of the push-pull 59’s. The ’phones connect between the two free pigtails on the condensers. To silence the speaker when the ’phones are being used, fit a switch in one of the leads from the secondary of the speaker input transformer to the voice coil.

THE TIME SIGNALS. There appears to be considerable uncertainty about the meaning and the necessity for those noises which immediately precede the common broadcast announcement, “ The two minutes past time signal has just passed.” Unless there are very special circumstances preventing it, the time signals are hoard from the national stations three times daily—at ’10.30 o.m. and 3.30 and 7.30 p.m., New Zealand standard time. They originate from the clock at the Dominion Observatory, Kclburn. The evening signal is one long impulse only, beginning at 7.30. The other two each begin with a long impulse, followed by ‘ single" short ones for a minute, when the second long “buzz" is heard, double short impulses following until the final long one a minute later. Apart from disturbing those listeners who look upon Sunday afternoon programmes purely as a sedative, the time signals are of great assistance to mariners checking their chronometers, to scientific bodies, watchmakers, and harbour boards.

8.8. C. ORCHESTRAS. At the end of 1935 the British Broadcasting Corporation maintained a symphony orchestra of 110 players, a theatre orchestra of 30, a variety orchestra of 16, and a dance band of 17, as well as the Empire orchestra of 22 players, and military band with 37 performers. The Amateur Choral Society has 250 voices and the professional chorus 48. There are also two octets and three provincial orchestras of 35 players each, besides new combinations to be formed in Scotland and Wales.

NOVEL MUSICAL THEME. Included in the 8.8.C.’s Queen Mary broadcasts was a symphonic rhapsody in the modern idiom entitled "Transatlantic Rhapsody.” _ The composer, who was specially commissioned by the 8.8. C. to write this work, is Mr Oeoige Posford, who achieved world-wide succ<;ss_ with his "Good-night Vienna” and “Invitation to the Waltz.” The “Rhapsody” is descriptive, first portraying the departure and the colossal activity at the docks and then forming a kaleidoscope of cheering crowds, bands playing and sirens of tugs, as the giant liner leaves the quay. Trie second theme ig the open sea —a romantic theme on the grand scale, depicting the achievement which the Queen Mary represents in British shipbuilding. Theme three seeks to represent the conflict between two great forces —the-, ship’s mighty engines and fjie sea. Next comes a-descriptive picture of life'aboard with its dance bands, swimming pool, cabarets, etc. The finale provides a glimpse of the mighty liner qs she ploughs her way through the seas on a moonlit night.

THE VOICES OF PARLIAMENT. Referring to the criticism made recently by Mr Farquhar Young, a well-known Christchurch elocutionist, regarding the voices of members of Parliament heard lately over the air, the Prime Minister (Mr M. J. Savage) admitted to the editor of a weekly journal that there was a great deal in what Mr Farquhar Young had to say. “With broadcasting, members have come to realise that they have to be doubly careful of their speech,” said Mr Savage. “Myself, I often find myself raising my voice unnecessarily—the knowledge that I am on the air is curing me of that fault. Of course, there are some voices that will never be pleasant to hear, no riiatter how much training they have, but, nevertheless, it is all to the good if broadcasting prompts everyone to attempt an improvement in their speech.” No doubt many listeners have been shocked when hearing at least one or two members over the air.

' TUNING IN. Listeners who acquire a set capable of receiving the shortwave stations are apt to miss many stations until they get the touch of tuning-in to shortwaves. The general effect of a descent to short waves is that stations occupy a very small portion of the dial, so small in fact that often an imperceptible movement will tunc the elation right out. One has, therefore, to tune carefully and slowly. Twiddling the dials will not get results. This does not mean that tuning-in is difficult, but it means that one has to hasten slowly. Even when the art is acquired to perfection there is no guarantee that stations heard one night will be heard again. Short-wave stations are very variable. One can almost always pick up the Empire station, the Genpan etation, and the French. However, at the moment the 19-metre transmission of the German station is by no means easy to pick up. Two stations, Saigon and Shanghai, on 44 and 31 metres respectively, arc also elusive at present. The Australian short-wave stations, such as VK2ME, are, however, fair game almost every time they come on the air. The Russian station RVIS is still weak, but it poems to be returning to normal reception strength every week. This station, however, cannot be recommended so much for its programme value as for its distance and the weird speech that comes from it.

OLYMPIC BROADCAST. Those hundreds of listeners who appreciate the ball-by-ball descriptions of the test cricket put over the ether bv the Australian national network will be pleased to learn that the A.B.C. has completed arrangements for full cabled reports permitting of like graphic descriptions of the doings of the Australian team at the forthcoming Olympic Games, where the Commonwealth has representatives, in athletics, boxing, wrestling, swimming, rowing, sculling, and cycling. No announcement has been made by the New Zealand Broadcasting Board as to its intentions in this connection.

1 POLITICAL CONTROL. Many listeners are voicing grave concern at the prospect of political control of the ' Now Zealand broadcasting service. In

effect we have had political control, thinly veiled (eays an exchange), ever since the Broadcasting Company was brought out. The principle is bad, but political domination will continue whether the board is abolished or reconstituted. 'What listeners are concerned about is the manner in which control will be exercised under the new regime.

HISTORIC AERIALS.

Aerials associated with transmitting stations, broadcasting and commercial, cannot be * described as satisfactory structures from an artistic viewpoint. The necessity for strict consideration of electrical and mechanical characteristics does not permit of adequate treatment architecturally, but the modern aerial, whatever type it be, is, at any rate, a neat and symmetrical arrangement compared with the complex radiators of the early days of wireless. Hertz was the first to demonstrate experimentally the existence of wireless waves, but he never took his experiments outside the laboratory, and made no effort to transmit signals. Nevertheless, his name today is applied to an aerial system which docs not make use of an earth, a type which is widely used by short and ultrashort wave transmitters. Those that followed Hertz, including Marconi, for a time adopted his type, but it was found one-half of the Hertz arrangement could be replaced by the earth. The earthed type of aerial was generally referred to as a Marconi aerial. Marconi’s first transmissions in England were carried out with the helpi of reflectors, but later he used metal sheets, which, especially when elevated, he found more effective. Later it was shown that the sheets could be dispensed with, leaving the wires alone, a fact which gave rise to the use of the term “ sky rode.” It was also found that a multiple arrangement of wires was more useful than a single wire, and all sorts of complicated systems of cylinders, cones, and other patterns came into being. When the advantage of height was realised elaborate efforts were made to erect high wires. Balloons and kites were used for temporary installations. It was on an aerial 400 feet long supported by a kite that the first Transatlantic nals were received at St. John’s, Newfoundland, from Poldhu, in Cornwall, on December 12, 1901. For these experiments a series of elaborate preparations were made. The first Poldhu station had an aerial of about 2000 vertical wires 200 feet high arranged round a circle of 150 feet diameter. A similar arrangement was erected at Cape Cod. Massachusetts, but before anything happened both stations were destroyed by storms. The rebuilt Poldhu transmitter used a fan-shaped arrangement of wires between two masts, the wires concentrating upon a building about halfway between the two. This fan-shaped scheme was extensively used at that time. The permanent Glace Bay (Nova Scotia) station used a similar arrangement, but in that case four towers each 250 feet high wore placed at the corners of a square, 75 yards on each side. The towers were joined at the tops by heavy cables, at intervals along each of which a hundred wires were fixed. All these wires converged on a building housing the transmitting apparatus at the centre of the square, the whole forming a kind of inverted pyramid. This station sent its first mceage to England in December, 1002. In those days, although the earliest experiments had been earned out with waves, the lengths of which were measured in centimetres, the practical transmissions were made on wavelengths which, by modern standards, are long waves, 10,000 to 20,000 metres. It was considered that wavelengths of less than 300 metres were useless for any purpose. Further, the receiving apparatua was entirely without amplifying powers. The valve in any form was unknown. Consequently, the whole success of a system depended upon the ability of the transmitter to radiate sufficient power to operate crystal detectors or their predecessors often thousands of miles away. The transmitters were of the spark type, and aerials of the type referred to, that is, arrangements having a high capacity were necessary at the transmitting points in order to brim* down to reasonable limits the high voltages applied by the transmitting equipment. The same kind of “ pavilions ” or “ tents,” as they were termed, were considered desirable for receivers because they “gather the waves over an extensive service, and concentrate them on the receiving apparatus, multiplying Hie effect that would accrue from a single wj,re.”