RADIO NOTES

Dominion, Volume 26, Issue 39, 9 November 1932, Page 6

RADIO NOTES

By

“ETHER ”

CURRENT TOPICS If the radio authorities are sufficiently intrigued with the result of the last questionnaire perhaps they will feel constrained to give us a new set of questions to answer with our next license. If this is done it would be interesting to frame a question to discover just what.sum.of money the public is prepared to produce for the purchase of a radio sot. Motor-car manufacturers have a pretty shrewd idea what the public will spend on motorcars. They have calculated to a nicety just how many purchasers there are in the various price ranges. In the case of radio sets the pace has been set by the price. In the long run this may prove to be a doubtful advantage even to the purveyors of radio sets themselves. That little saying about the higher the fewer .seems very apt in this case. An era of cheap radio sets would start a. ball rolling .that would benefit everyone. More listeners means more licenses. More licenses means more radio sets. More radio sets means more Customs duties and more work.

The Sunday programmes from 2YA still insist on going their own way apparently without any reference to whether the listener, is likely to be listening or •; not. Perhaps there is some very good reason why the programme starts at 2 p.m. in spite of the fact .that, this, would be a more suitable time to conclude a programme. Possibly on wet days there may be a few listeners anxious to kill time indoors between 2 p.m. and 4.30 p.m. In the summer, with hope of fine days still uppermost in everyone’s mind, the majority of people must be in the open air during that period. Those at home are probably asleep. Under the circumstances it would seem likely that far more listeners would appreciate the good fare provided during lunch time, say, from 12.30 to 1.30 or 2 p.m.

Even the most -exacting critic must have had reason to feel satisfied with some of the star items of the last week or • two. The symphony concert in the Town Hall was up to its usual very high standard. There-is no doubt that this concert sets the pace for local transmissions. In, their turn the broadcasting authorities do full justice to the excellent musical,fare provided at these concerts. They seem to have “taped off” the acoustical' properties of the Town Hall to a’nicety. The male chorus of the Imperial Grand Opera was a treat, whose one falling was that it does not happen often enough. Out of date as may be. the gear used in the transmitting department of 2YA it would seem that .the engineers are extracting everything from it that they can. Keen ears may perhaps note a lack of deep base. Modulation may not be so deep as in more modern stations. Nevertheless, there,'is every indication that the engineers have been putting in hours of painstaking work.

Some manufacturers are turning their attention once again to the structural arrangement of . the electrode system, with the definite object of making it proof against vibrations received from the loudspeaker to the bulb of the valve, or via the valve support There has been some difference of opinion as to whether the microphonic effects would best be avoided by making the electrode system springy—that is to say, rigid in itself but mounted upon springy supports—or by making it as rigid as ever possible.. It is not rpally the lyibratidns.off the’electrode system as a/whole that matter, but rather the vibration of one part of the electrode system in-relation to another.

Trouble has arisen in Austria on a little question of thirty millions of schillings. According to a correspondent of an English paper, the Post-master-General is this amount short on the year’s working, and the Finance Minister considers he should make up the deficit from his own 'pocket. It is but a step .from the Post Office to the'radio cash box, and fears are genera ['.among listeners that the Post-master-General, who is also Chief of the Austrian Broadcasting Co., will use listeners’ money in order to fill the breach. Listeners are protesting, but the fund is in danger.

Doubtless the Admiralty announcement about the formation of an auxiliary reserve of radio operators has interested many New Zealand enthusiasts. Here are the details of the scheme: The idea of such a scheme has been broached on jnore than one occasion in recent years, but again and again difficulties have been encountered; it was, therefore, extremely 'gratifying to the Radio Society of Great Britain to be approached on the .question , in January last, when the 'Admiralty asked whether the society would be prepared to give its support /to a naval reserve scheme. It is understood., that training for positions in the "R.N.W.A.R. will be decentralised as far as possible, taking the form of instructional classes. organised by ' a ,unit- petty officer. There will be two types of training, (a) for operators, (b) for watchers. Periodical proficiency tests will be arranged and handbooks of instruction issued by the Admiralty. Test transmissions on special wavelengths and using naval call-signs will be given at pre-deter-mined intervals. Candidates will be enrolled as watcher first or second class or as operator second class, advancement being made as a result of periodical ability tests. Candidates must be over IS years of age and of British parentage. Enrolment is not open to men serving with H.M. Forces or to members of any police force. ADAPTORS In the case of a broadcast set which has no high frequency amplifier, but is just, say, detector and one or two L.F., a short-wave adaptor is virtually a separate detector valve with its own coils and condensers. The detector of the broadcast receiver is removed.from the socket and the adaptor is plugged into the detector socket instead, the detector valve being used in the valveholder of the adaptor. Of course, it is not necessary to use the original detector valve in the adaptor, and you can use another valve if you have one which is more suitable. The adaptor itself is provided with tuning controls, and when it is fitted to the broadcast set the tuning is done by means of the adaptor and not by means of the tuning controls of the set. Although the fitting of a short-wave adaptor, as mentioned above, is simple in principle, it is not always quite so simple in practice as if sounds, and if you are thinking.of going in for a shortwave adaptor it is as well to get the necessary advice upon the requirements of your particular broadcast circuit 1 from an expert.

THE RADIO CAR Kilowatts Through Air PICKED-UP POWER One hears so much about using the ether to transmit power that the following article by G. 11. Daly may help to clear up a few fallacies. Writing in “Popular Wireless,” he says: The motor-car of the future, it is prophesied will be a radio car. The car will be propelled silently by electric motors which will pick up their power from the air by wireless. From t<be wireless point of view what are the prospects of this interesting forecast coming true? ' f '!?'f

The smallest of our motor-cars requires a minimum of . seven horsepower to move it along, and this engine develops.a much. greater horse-power when it is running. Electrically, this horse-power is ■ rife equivalent of 5222 watts, or-j almost 5J kilowatts, and at the present time 5i kilowatts would take a great deal of ■ collecting from the atmosphere, especially with the present device for collecting wireless energy—i.c., the aerial. The . power of the wireless stations in this country (Britain),' varies from •} kilowatt to the 1000 kilowatts of Rugby, but on the average a wireless station only radiates a bare 20 per cent, of the power supplied to Its generators, and then only an infinitesimal amount of this radiated and far-scattered energy is picked up by the wireless 'receiver. Also, the farther the receiver is from the transmitter the less the energy which will be picked up. If we place the number of wireless stations which are regularly operating in Great Britain at 1000, and allow them a power of 5 kilowatts each, then . if these stations radiate 20 per cent, of their energy, it follows that there are only 1000 kilowatts of wireless energy being radiated over the whole of this country. Of course, there is a certain amount of wireless energy overflowing from the Continent and the rest of the world which, by the way, many of us think we could very well do without; but, despite this, 1000 kilowatts of wireless energy is a broad estimate of the wireless energy let loose over Wiese islands.

This amount of energy would only be sufficient to drive, shall we say, 200 baby cars—always provided they could pick up 1 the ehergy without any appreciable, loss. , ' . Before, we can have, the , wireless motor-car we must radiate the equivalent electrical’power of the, thousands of motor-cars which are at' present on the road, also, we must discover some less'primitive' method of collecting this wireless’power—both of which achievements seem/ very remote at present. ■: ■ ' '

However, the outlook for the wireless motor-car is not nearly so black as all that. Although there is very little artificially-created wireless energy in the atmosphere, there is, more than sufficient natural wave energy to run all the machinery in the world a thousand times over. The sun, for instance, radiates 4,200,000 tons of heat per second, and when we consider that a mere pound of heat will supply 2,000,000 horse-power for a year, then we can appreciate the tremendous energy which the sun sends over to us every day.

Numerous attempts have been made to collect this energy, but while a fair amount of success, has been attained the apparatus is cumbersome and unwieldj;. ■'Nevertheless, there is little doubt- that the/.time will come when this'natural energy will be tapped effectively./. i-v -'-/" Then, again, the. wireless waves which Supply our concerts may also run our motor-cars, in spite of their present feebleness. That is to say, the 1000 kilowatts, or the 200 horse-power of wireless energy, which is at present spilled into the air over England, may supply all motor-cars, far-fetched as it may sound. ,

For example, although a 'baby car requires seven horse-power to run it along, a very large proportion of this energy is wasted in excessive friction, heat, and so on; but if we could reduce or eliminate these frictional and heat losses, it would be possible to run a car as effectively as at present on a fraction of the horst-power.

There is considerable hope in this direction, because, unlike other artifi-cially-created energy, wireless energy appears to experience very little friction. Nature has'a system of its own whereby work can be done without any friction whatsoever. RECEIVER. TYPES Straight or .“Superhet.” SOME COMPARISONS ' The essential difference between the two receiver types lies in the method of tuning from one station to another. ,In the straight set, every tuned circuit throughout the receiver is tuned to the frequency of the incoming signal, and when changing from one station to another, it is necessary to change the resonance frequency of each circuit by adjusting the variable condensers. Now the amplifier portion of a superheterodyne is very similar, and consists of valves coupled by coils and condensers which form resonant circuits tuned all to the same frequency. No provision, however, is made in this amplifier for varying the tuning, the amplifier is fixed, and designed to function at only one frequency. In order to make use of it, therefore, it is preceded by a piece of apparatus whose purpose it is to change the frequency of the desired station,to that of the amplifier. Instead of tuning by adjusting the amplifier to operate upon the signal frequency, as in a straight set, we work the other way round, and alter the frequency of the signal to conform to the requirements of the amplifier. The fact that the amplifier, or as it is usually termed, the intermediate frequency amplifier, is required to work only upon one frequency leads to a number of important points. Provided that-the frequency-changing process be carried out with constant efficiency, neither the sensitivity nor the selectivity of the receiver will vary over its tuning range, and the quality of reproduction will also be unaffected by the frequency of the signal. Furthermore, we have the opportunity of using special types of circuit in the amplifier. Perhaps the chief point, however, is that within limits we can- choose the particular frequency upon which the amplifier is to operate. With ordinary tuning circuits, the lower the frequency the higher the selectivity and the greater the amplification which can be obtained. The intermediate frequency, therefore, is nearly always chosen to be considerably lower than that of the Incoming