THE WIRELESS WORLD

Otago Daily Times, Issue 22023, 4 August 1933, Page 2

THE WIRELESS WORLD

NEWS AND NOTES

By Maos a Vox.

Items of local interest arc invited by “ Magna Vox ” for publication in this column. It is necessary that such matter should reach this office by Tuesday of each week for insertion on the following Friday. 2BL, Sydney.—Bss K.C., 353 metres. 2FC, Sydney.—6os K.C., 422 metres. 3AR, Melbourne. —020 K.C., 492 metres. 3LO, Melbourne.—B3o K.C., 371 metres. SGD, Adelaide.—73o K.C., 395 metres. 4QG, Brisbane.—76o K.C., 385 metres. IYA, Auckland.—B2o K.C., 365.8 metres. 2YA. Wellington.—72o K.C., 420 metres. 3YA, Christchurch.—9Bo K.C., 306 metres. 4YA, Dunedin.—6so K.C., 463 metres.

ANSWERS TO CORRESPONDENTS. ‘‘Resistance,” Dunedin. — (1) The substitution of 50 mfd. electrolytic _ condensers as by-pass capacities is quite a practical expedient, and will generally bring about a noticeable improvement in the proportional reproduction of the lower register. Condensers of this capacity and rated to work at 12 volts (quite enough for all stages except perhaps the output), cost only a few shillings. (2) There is no local agency for the component you mention.

“Battery,” Fairlie.— (1) Towards the end of the charge “ gassing ” usually occurs, and the escaping bubbles take away water with them. The acid is therefore more concentrated than it would be otherwise, but it is restored when you “top up.” (2) Give it a wide berth. The fact that the trials were unsatisfactory would indicate that something is wrong. Moreover, if it is such a wonderful machine, why is the owner so anxious to be rid of it ? (3) I could not say offhand, but if you forward me a rough plan of the circuit I could probably advise i you. “Aerial,” Seacliff.—There is nothing wrong with, the idea as far as I can see, and theoretically such an aerial should give every satisfaction. I have found, however, that it is a somewhat ticklish business giving advice on any particular , design of aerial. For instance, a listener living in my neighbourhood did not discover until recently that his aerial had been lying across the iron roof of his house for the past two months at least, and yet during that period his reception was quite satisfactory. NEW AMERICAN VALVE. It is understood that a new type of valve will shortly be placed on the market. This valve (for it is actually ! enclosed in a glass bulb which is like i an ordinary valve) is in one sense a gas-discharge tube. To outward appearances it looks very like an ordinary valve, and the glass bulb is fitted into a stand- j ard type of valve base. One form of the . device is a small fuse-like tube containing j two internal electrodes and having a third element in the form of a narrow clip or band that is placed around the middle of the glass container. In actual tests these filamentless valves have been used as detectors, oscillators and amplifiers, and are claimed to be able to perform all the functions of the ordinary modern valve. These valves are still more or less in the laboratory stage, but the teste with them have proved so promising that the inventors hope to have them on the market very shortly, CONTROL OF TONE. A new “ colour ” radio has been introduced in America which embodies what is described as a combination of colour and musical. tone. This colour radio uses a double-action tone control, so that the high and low notes are controlled independently of each other. There are two knobs, with a rainbow-coloured path of light between them. This rainbow arch on the left, representing the bass register, with a dark blue colour, merges gradually through red to a golden yellow colour on the right, indicating the treble. As the left knob is turned and the bass notes diminish the amount of blue light visible in the colour atrip is correspondingly reduced. In the same way if the right knob is turned and the treble notes are reduced the amount of yellow light _is reduced. In addition to the illuminated dial, calibrated in kilocycles, I there is another graduated dial against which the shadow of a meter needle is thrown. To tune_ a station into perfect resonance the tuning is adjusted until the needle moves the maximum distance to the right. The volume control is also in the form of a visual indicator, a point of light moving across, a colour path. AUTOMATIC BIAS. When you are dealing with a mains set, automatic grid bias is a definite advantage because you can use the mains supply for h.t., 1.t., and grid bias, and therefore have no requirements for any battery at all. After all, if a set is to be a mains set in the proper sense of the term, there should be no need to trouble about any battery maintenance whatever, even a grid-bias battery, which only requires attention perhaps every six months or so. When it comes to a battery-driven set, there is not very much point in using the automatic grid bias. It is true that even here it reduces the number of batteries requiring attention from three to two, but the_ one which is disposed of in this way is by far the least important from the point of view of maintenance. Excellent grid-bias batteries can be had now for a matter of pence, and so there is really nothing in it on that score. On the other hand, if you change over from battery bias to automatic bias you will require other components, such as condensers, decoupling resistances, and so on, especially if there are more circuits than one to be biased, and you will find that the actual cost will be considerably greater. Even the apparent saving on the cost of the grid-bias battery is something of an illusion, because if you think about the matter for a moment you will see that the automatic bias arrangement really derives its bias from the h.t. battery, because the effective h.t. voltage is reduced bv this amount. So you might just as well use an h.t. battery divided for grid bias in the ordinary way.

RADIO IN THE CAR. The following criticism of a modern motor ear set which appeared in the latest issue of the Wireless World should prove of interest to motorists who propose having their machines fitted with wireless;—"Low-tension current for the valves is drawn from the car battery, which also drives the h.t. generator and energises the speaker field. The six valve stages of the set are arranged as an h.f. amplifier, a four-electrode detector-oscil-lator, one i.f. stage, a combined doublediode detector and A.V.C. valve, an intermediate I.f. amplifier, and finally a pair of push-pull pentodes. Ample volume is obtainable, even when the car is travelling at a good speed, and, as for range, some 15 or 20 stations were found to provide signals of programme value in broad daylight, on the open road, in spite of tlie necessarily limited pick-up of the small aerial which is built into the roof. Without automatic volume control a car set is of little practical use while the vehicle is under way, a s continuous adjustment is needed in order to compensate for the screening effect of bridges, buildings, etc During our test such obstacles made practically no difference to reception, as the control system proved to be well capable of holding signal strength at a comfortable level. Bearing in mind the limited baffle area of the loudspeaker, quality was all that one could expect or wish. Interference from the electrical equipment of the car was almost non-exist-ent, and even that from passing tramcars could hardly ever be detected. Spark-plug suppressors, etc., are, of course, fitted where necessary to the electrical system of the car." PACIFIC WIRELESS NETWORK. The British islands in the Pacific, scattered as they are over vast spaces of ocean, represent the extreme limit of worldly isolation, yet they are bound together hv invisible links which permit communication with the same expedition as between the crowded cities of the world. Between the Solomon Islands, the Gilbert and Ellice Groups, the Fijis, and the mainland of Australia stretch an interlacing grid or network of wireless channels connecting that great area with the outside world and each part with the other. In the early days of radio a few small wireless stations were established by the British Government in Fiji and the surrounding islands. These were controlled and operated by the British Admiralty from its headquarters in London. Realising the development and importance of the various British island possessions in the Pacific and the enterprise manifested by other nations in establishing wireless stations on their island possessions in the Pacific, Mr Fisk (managing director of

A.W.A.) suggested to the Right Hon. L. 8. Amer". then First Lord of the British Admiralty, that Amalgamated Wireless take over from the Imperial Government all the wireless stations in the Fijian group with the object of modernising and operating them as units of the Pacific network already operated by A.W.A. An agreement was completed between the Imperial Government and the company m 1922, and to-day these stations are equipped in the most modern way. The I speedy and accurate communication facili- ] ties thereby provided are greatly assist- | ing the Fijian business interests. The most important of the Fijian wireless stations is at Suva, which collects and distributes wireless traffic to and from all islands in the North and South Pacific which have wireless communication. It handles overseas traffic with Great Britain and the Continent and North and South America via Sydney Radio and the Beam Wireless Service. Sydney Radio is also in communication with such import island centres as Samoa, the Friendly Islands, Gilbert and Ellice Islands, New Caledonia, New Hebrides, and Honolulu. Communication is also maintained with the four other Fijian stations —Labasa, Savu Savu, Taveuni, and Lautoka. An important radio centre of the Pacific network is in the mandated territory of New Guinea, where the company’s chief station is located at Bita Paka, near Rafiaul, on the island of New Britain. This modern station maintains direct radio communication with Sydney and with the following stations: —Aitapc and Madang, New Guinea; Manus, Admiralty . Islands; Kavieng, New Ireland; Kieta, • Bougainville Island; and Wan and Sala- j moa, on the New Guinea goldfields. It ; also communicates with the Gilbert and j Ellice, Solomon, and Santa Cruz Islands. \ At Port Moresby, in Papua, is another i unit of the Pacific network. From here j communication is effected with Samardi, ; in Papua; with Thursday Island, and with i Cooktown and Townsville, in Australia, j The principal Australian wireless stations j handling traffic between Australia and j the Pacific are located at Sydney, Bris- j bane, and Townsville. These in turn are intermediary stations between the Pacific and the Beam Wireless Service connecting Australia with Great Britain, the Continent, and North and South America. Thus the island resident is able to com- i municate by wireless with any part of | the world. It will thug be seen that Mr ■ Fisk’s ideal of a British network in the j Pacific is in course of realisation, and ; that Australia is fast becoming the important wireless clearing centre of Pacific communications. HERE AND THERE. The unfavourable conditions with which country listeners in the Commonwealth have to contend has led to the formation of listeners’ leagues in many centres. These bodies are performing much useful work in bringing the shortcomings of the service to the notice of the technical and programme authorities. Local interference of the type due to imperfections in ; the electricity supplies is also a matter which has received much successful attention. One of the oldest and most active of these bodies is the Richmond River Listeners’ League, which has its headquarters at Lismore, and which has its own experimental transmitter (VK2GL). It has just closed another year of useful effort with the knowledge that the district will, after many years of neglect, soon be provided with a relay station.

It is now possible to gain from Empire listeners’ letters an impression of the kind of programme most appreciated. Broadcasts of incidents and ceremonies which belong peculiarly to England are popular. At the top of the list undoubtedly is Big Ben, and it is closely followed by the official weather forecasts. Descriptions of the trooping of the colour, military tattoos, and the ceremony of the keys, talks by well-known people, especially on educational topics, and sporting news are always welcome throughout the Empire.

The largest wireless station in the East, costing 1,000,000 yen (£IOO,OOO at par), is to be built at Kurume city, according to a decision of the Japanese Government. It will have a power of 100 kilowatts, and will, it is claimed, be able to neutralise the activities of Russian stations and of the Chinese station at Nanking. sjc i!t »t«

There are many events which happen when the great majority of people are removed from the opportunity of listening to running descriptions of them. Modern broadcast practice is adopting a means for vivid reproduction of the stories of such _ events at hours of "maximum listening.” 1 It is not a case of allowing an announcer to recall what he has already described, or of reading a newspaper account, but of the reproduction of the original description from a recording made from it. New Zealand hardly offers yet the field which would warrant the expense of providing such a recording system, but the time is approaching when one will be valuable to our main stations. This recording system offers another advantage of which the 8.8. G. in particular avails itself. It broadcasts “ reminiscent programmes,a selection of attractive specialties which have already found favour early in the year. Thus can come, at the end of, say, 1933, an epitome of all of outstanding importance that radio has passed on during the year.

The elimination of “ phantom ” stations (i.e., those which have used more than one set of call letters for the same transmitter) has led to an apparent reduction in the number of Canadian broadcasting stations, the official list now standing at 50. Most of the stations have been given new wavelengths based on the United States-Canadian Agreement of May, 1932, which aims at preventing interference between transmitters in the two countries.

Vienna’s new 100-kilowatt transmitter at Bisamberg will have Europe’s highest aerial mast, even exceeding in height the famous Eiffel Tower, which is 1000 ft high. The mast itself constitutes the aerial, and the uppermost parts operate on the telescopic principle for rough tuning purposes. The station opened a few weeks ago, using a wavelength of 507.2 metres.

A total of 43 broadcasting stations is provided for in Norway’s new three-year plan, which has been started with the construction of the 20-kilowatt station at Bergen, and relays by Kirkenes, Kristiansund, Stavenger, and Tromso. The existing Trondheim station is to be increased in power from 1.2 to 25 kilowatts. The entire scheme should be completed before the end of 1935, by which time, presumably, the Lucerne plan will require an extensive overhaul.

The British Broadcasting Corporation’s new organ, which cost £IO,OOO, has 2362 pipes and 150 electric stops, and is so equipped that the organist can play it in a studio remote from the concert hall by means of a duplicate console. A loudspeaker in the studio will enable him to hear his own recital exactly as it is received by listeners.

The Kina was heard on the wireless twice during June—once at the opening of the World Economic Conference, and again when he performed the opening ceremony of South Africa House, Trafalgar square. Listeners were familiar with the arrangements which have been made for broadcasting the World Economic Conference, but no announcement had been made regarding his Majesty’s second broadcast, because it was at first intended to be an Empire broadcast for the South African zone only. Very naturally, however, South Africans were most anxious that the whole world should hear his Majesty honour their country.