RADIO RECORD

Greymouth Evening Star, 10 February 1938, Page 9

RADIO RECORD

NOTES FOR LISTENERS-IN

(By

“Reception”)

EFFECTS OF SUNSPOTS.

I ON RADIO AND TELEGRAPH. The close association of abnormal sunspot activity with magnetic earth currents and displays of the Aurora Australis is being demonstrated at present, in connection with the operation of New Zealand’s radio and telegraphic communications. So strong are the earth currents on some occasions that telegraphic working of the normal character, utilising the earth as a return circuit, has been seriously interfered with. There has been no actual suspension of the busy flow of traffic —the telegrams handled in the quarter ended last December exceeded one and a half millions in numbers —but earth currents became so strong on January 17 that Wellington telegraph office reported indifferent working conditions from 10.30 a.m., particularly on circuits running east to west. By 11 a.m., practically every circuit was affected, even those running north and south, which is an exceptional circumstance. Advice was received at the same time from Christchurch, Blenheim and Nelson, that earth currents were affecting the lines of those districts.

The great bulk of telegraphic business is done with the Murray Multiplex and the Creed teleprinter, both dependent for their efficiency on a very deliberate balancing of electrical currents. However, under the magnetic conditions which have been experienced intermittently since January 17, the line currents have occasionally been thrown out of balance by the strong earth currents and accurate work on these delicate instruments, seriously handicapped. Operators then turn to the old method of Morse key until the worst of the disturbances is over. Recent experience on the telegraphic circuits shows that earth currents must at times have reached a strength of 40 milliamperes, as they reduced the battery current of this strength down to zero. Fortunately these disturbances are not continuous, but they have been reported daily for over a fortnight, and are not expected to completely disappear for a long, period. As a direct connection has been proved between sunspots and magnetic storms, it may be expected that the maximum period of severity will not be reached until some time in 1939, after’ which the phenomenon will gradually abate, and the next maximum period will not be reached for eleven years. Telephone communication, which is wholly on metallic circuits aud is not dependent on an earth return circuit, has not been handicapped, nor is there any appreciable interference with local radio broadcasting, except that there may be occasional difficulty in securing steady reception of distant stations.

In the short-wave radio field, however, sunspot activity has frequently caused a complete wiping out of the 31 metres Daventry signals, forcing listeners to utilise the shorter waves of the Empire station, such as 19 metres. The popular wave lengths for Daventry receptions a few years ago were 25 and 31 metres in New Zealand, but under the disturbed conditions, due to sunspots, it will be found that the 19-metre band will generally be more reliable. There is a very interesting technical reason for this which is thoroughly understood. Under less disturbed magnetic conditions, 27 metres has been as low a wave length as it was necessary to use for summertime working of the radio telephone between New Zealand and Australia: but to meet present abnormal conditions it has been necessary to arrange to use a much shorter wave length. Awarua radio-station operators, during a recent experience of maximum interference with short-wave working, simultaneously noticed what they described as the best display of Aurora Australis they have ever seen. They report frequent failures to maintain communication between 36 metres and 100 metres, but greater success in using the shorter waves- This station is responsible for the daily receipt of British official wireless news transmitted from Rugby on various shortwave frequencies and also on the long wave of 1800 metres. While the latter might have been regarded by many as thoroughly out-of-date and completely superseded by short waves, its value has been proved during the period of sunspot activity by the fact that these long daily reports have been most reliably received in New Zealand through the medium of the long-wave band while short waves were, at times quite ineffective.

Portishead, the British short-wave transmitting station, has reported its recent difficulties to New Zealand short-wave stations, and Awarua on a recent occasion was able to assist this station in communicating with the| British survey ship, “Discovery,” en route from Fremantle to Dunedin. The “Discovery” had been unable to maintain its daily short-wave schedule with Britain, but the Portishead messages were picked up by Awarua, which got into communication with the “Discovery” on the shorter wave, and passed on the British messages. New Zealand's commercial radio stations maintain daily schedules with a number of points in the South Pacific, and this important work has not been completely held up, although it has been handicapped by the vagaries of the highly ionised atmosphere due to sußspots and consequent magnetic storms. HEA.T-DRIVEN RECEIVER. A_ heat-operated battery charging unit has been sloped in England. E t onerates on the “Thermo-couple, principle, a number of junction points of dissimilar metals being heated and the voltage thereby created producing a useful amount of current. Gas was used in the models shown, but there appears to be no reason why other fuel could not be applied. Where electricity is available there would be no call for this scheme, but there is a chance that it may, one day, be of some use to those who are remote from cheap sources of power. At this stage it would not be wise for country listeners to imagine that their power supply difficulties are solved again. As mentioned in this column a few months ago, a kerosene operated hot air has been developed for battery charging in Germany.

EXPENSIVE RECEIVERS. 1938 SALES PREDICTION. Manufacturers of wireless receivers expect that this year a greater proportion of their business will b© done with sets of th© more expensive type. The replacement business is becoming more important, and the owner of a set must be offered something with a marked superiority in performance before he will change. As the number of licenses increases it is obvious that fewer people become owners of wireless receivers for the first time. This proportion will gradually decrease until when saturation point is reached, if it ever is reached, the license increase will be at a rate comparable with that of the growth of population. As this state is approached the old selling argument—namely, the entertainment that is missed by not owning a set —will disappear. Sets with new technical features which will give a decidedly superior result compared to those now in use will be the only way that manufacturers will be able to maintain the demand.

There will, of course, always be some demand for the cheap set which, in the interests of broadcasting aud all connected with it, has done yeoman service in bringing in tens of thousands who could not have otherwise become listeners. This great body, which has been the backbone of the receiver manufacturing industry, aud of the broadcasting services, is more likely to use its sets for many years than those who are able to acquire a more expensive article. But those who can do so are not likely to purchase a new set merely because it is new. They will want a fairly strong inducement. It will be interesting to see how manufacturers will provide this inducement.

Tho story of the development of broadcast receivers shows that more often than not purely technical features have not had the appeal that more superficial features have had. A manufacturer who has spent something on improving the quality of all the components and generally making his receiver a better product has not always had the success_pf one who has concentrated more on imposing outward signs.

The listener has always led the manufacturer a merry dance, and because he generally wants to the maximum degree things that arc inconsistent, such as good quality combined with dis-tance-getting, and because in many instances he has not either the desire nor the ability to operate his receiver to the best possible advantage, designers have had to exercise considerable ingenuity. They have risen to the occasion and have produced automatic arrangements of all kinds, tuning indicators, and many other gadgets which, as far as they can, counteract the evil effects of mishandling. The present tendency is to follow this practice, and, further, to devise means which will save the listener the manual labour of moving the tuning arrangements from one station to another. All this has obviously added to the complexity of receivers, and has made the problem of servicving and repair far inure difficult. It has also added to the cost, but this has been offset by corresponding improvement in manufacturing technique, while research has produced materials which have greatly reduced the risk of breakdown. The desire to meet these demands has produced something far more important than a broadcast receiver. It has added greatly to the general know.edge of electricity.

MORE DUAL-WAVE MODELS. If information to hand on 1938 model receivers is reliable, there will be no julstanding changes in desgin and con-, itruction. Apart from midget four/alve sets, there will be few models which will not cover the short wave bands. There will be wider use of tuned iron core intermediate transformers, with .heir greater selectivity and amplification, and -with such equipment many models will include variable band-pass, oennitting, at will, needle-sharp tuning jr wide, high fidelity reception. The cathode raj’ tube, which has enjoyed deserved popularity under the name of “magic eyb,” is being develop’d to respond to the weakest signals •eceivable and at the same time to act .s a pleasure of signal strength. Great flaims in the way of ease in tuning are jeing made for a 10-band all-wave receiver. If this new system proves all :hat is claimed it will certainly be an advance on the more usual four-band .eceivers, the successful use of which in the shorter waves necessitates a flow-motion dial. LISTENERS’ PANEL. No fewer than 47,000 listeners volunteered to serve on a panel that has been formed by the British Broadcasting Corporation to gauge the listenerresponse to light entertainment programmes. These offers were received within three days of the request made rver the air by Mr. John Watt, director if variety for the British Broadcasting Corporation. As a result of this overwhelming response the corporation ias decided to enrol 2000 of the applicants by the expedient of accepting each twenty-third offer. Each listener m the panel is to be supplied with a erm giving details of the light entertainment programmes to be broadcast j ver three months, and will" be asked to answer briefly just three questions: — (a) How much of the programme did you hear? (b) Did you start listening after this programme iad begun? (c) Did you stop listening before the programme had finished? Though the most ambtious from the point of view of the size of the panel, this is not the first such inquiry on die part of the British Broadcasting. Corporation which goes to considerable lengths to ascertain the opinions of listeners on the fare provided.