THE WIRELESS WORLD

Otago Daily Times, Issue 21981, 16 June 1933, Page 2

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 for insertion on the following Friday. 2BL, Sydney.—Bss K.C., 353 metres. 2KC, Sydney.—66s K.C., 422 metres. 3AR, Melbourne.—62o K.C., 492 metres. 3LO, Melbourne. —830 K.C., 371 metres. SCL, Adelaide.—73o K.C., 395 metres. 4QG, Brisbane.—76o K.C., 383 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. “Oscillation,” Ranfurly.— (1) I should say that the connections to your reaction condenser arc back to front. Try reversing them. If this does not produce the required result, increase the number ot turns on the reaction coil. (21 I like the idea of your proposed aerial, which, I imagine, should give good results. By making it longer, however, you should receive much stronger signals, and I should suggest raising the height of the rear pole to 50 feet. G. S. D.. Dunedin. —Electrons are boiled out of the filament or cathode, and proceed to the plate or anode to make up the plate current. The same movement occurs in any battery, generator, or rectifier circuit. In practice it is generally considered that the flow is from the positive to the negative, this assumption having been made before the precise nature of electricity or a current was known. “Voltage,” Kakamii. Between the points you mention voltage is equal to the plate voltage plus the grid bias, which may in some cases be fairly large. You will find it. necessary to take the negative direct to the cathode or (with directly heated valves) to the filament or the centre tap of a filament winding or of the resistance across such winding. DIRECTIONAL AERIALS. The precision with which, in the light of modern knowledge, broadcasting equipment may be designed is well realised from what has been done recently in the United 1 States. A station was interfering with another at night, and it was ordered to reduce its power, pending the elimination of the interference. The difficulty was overcome by designing the aerial so that the harmful radiation in the direction of the station previously interfered with was reduced._ As a result the first, station was permitted to revert to its original power. NEW YA PLANTS. Few listeners realise that since the board took control of our broadcasting it has purchased no fewer than three transmitting plants—all, by the way, from' Amalgamated Wireless, and all manufactured in Australia. These are the portable transmitter which will shortly make its appearance round Auckland; the auxiliary 2YA plant, which is showing remarkable range for its small power; and the new 3YA, now in course of erection on Banks Peninsula. The masts for the last-named, reaching- to a height of 320 feet, are now in course of erection, and it is quite likely that the plant itself will be ready for the air early in October. VOLUME CONTROL. Usually listeners of more advanced years prefer their music “ soft,” while the “ younger bloods ” crave for it “ full strength,” especially jazz’hiusic; b{it even those who like a high intensity for serious listening prefer it “ turned down *' when the music is to form only a background to other things. In short, the volume from the loudspeaker itself can never be automatically controlled, and manual adjustment must stay. The automatic volume control which is so much to the front at the . moment usually implies “ keeping the input to the detector valves the sapie for all stations and conditions.” The manual volume control, which must therefore always be provided on a receiver, as with a pick-tip, should preferably control the audio frequency reproduction—That is to say, it should .be a means of varying the magnification of the audio frequencies after the detector, so that this, too, is really .“ volume control.” The distinction is that the automatic arrangenients should precede the detector, especially if it is a diode, so as to keep its input constant, and therefore its efficiency and its freedom from distortion constant, while the manual control should follow the detector. Since it controls audio frequencies it is closely allied to the volume control for a gramophone pick-up. DETECTOR VALVE HINTS. When you are using reaction with a detector valve you will often find yourself being led more or less unconsciously into a compromise between the efficiency of the detector and the smooth and convenient operation of the reaction. The fact is that frequently we sacrifice quite a good deal of the efficiency of the detector for the sake of the reaction. Now this is not really necessary, and can often be avoided by giving attention first and foremost to the ‘detector, quite regardless of the reaction. Make sure that the detector valve has the proper anode voltage—the maximum that can be properly employed—and also that the best values of grid leak and condenser are used. Having got this all working properly, and without any regard in the first, instance to the operation of reaction, you can then turn your attention to the reaction circuit and make the necessary adjustment in that. It may be necessary, for instance, to try different values of reaction condenser and reaction coil, whilst the relative positions of the reaction coil and the tuning' coil can very easily be varied. Having done all this, if you still have not got smooth and easy reaction control, you may then perhaps sacrifice a little on plate _ voltage of the detector or make other slight adjustments of the detector conditions. As a rule, however, you will find that by adjusting the two circuits quite independently in this way the amount of sacrifice which you have to make in the operating conditions of the detector is very much less than before, if, indeed; you have to make any sacrifice at all. This is just one of those cases where a step-by-step methodical handling of the problem will work much. REMOTE CONTROL. How many people are there who, one time or another, have not wished they could control their wireless set without the need to rise from a comfortable armchair ? Very few. I know people who will-turn on the set early in the evening and leave it running until midnight, although no one listens to more than half the programme, and all because of the trouble of getting up to switch the set off and on again. It is sheer waste and bad listening. It is not to be wondered at that remote control —the ability to operate and control n receiver at a distance—is of interest to many people. True, remote control means that the receiver can be installed in any convenient place—an attic, or away on the top shelf of a cupboard—while in each room where one may wish to listen there are installed a loudspeaker and a control box. Each control box should he capable of switching the set on and off, controlling the volume, and operating the tuning condenser or condensers. For the ordinary listener, however, remote control means either a simple on-ami-qff arrangement or a gadget for controlling volume, or both. Aetna! tuning is not so simple. So far as volume control is concerned, a “remote control” is already fitted to a number of sets, and the principle is easily adaptable to others.

PERFORMING RIGHTS COMMIS

SION. ■ Mr Justice Owen as commissioner con- | ducting an inquiry into the operations of the Australian Performing Rights Association, has presented to the Commonwealth Parliament a report that is almost sensational in some of its findings. It contains very definite suggestions lor the limitation of the powers now claimed and exercised by the P.R.A., which requires such substantial payments before permitting the broadcast of musical and dramatic matter over which it holds copyright. If effect is given to the recoinmendations of the commissioner, legislation will provide that the Performing Rights Association file statements of all fees and charges it proposes to collect for the performance of any musical wbrk, and accounts of receipts and distribution of such fees. Until the time

fixed for such filing, the present right of the P.R.A. shall remain, and it shall lodge with the Commonwealth a security of £3OOO. The main object of the, commissioner’s recommendations is, obviously to bar possibility of exploitation of the public by extortionate claims for the granting of rights of performance. One stipulation made is that there shall be no charge for the broadcasting of works forming part of a religions service. It appears likely that the main outcome of the inquiry will be a considerable reduction in the annual amount of license revenue paid for the utilisation of copyright. This question, however, bristles with international complications, and it may be a long time before the whole matter is finally settled to public satisfaction.