RADIO RECORD I

Greymouth Evening Star, 17 May 1934, Page 9

RADIO RECORD I

NOTES FOR LISTENERS-IN

( By

“Reception” )

ELECTKO Ji V TIC CO ADE A S E RS. AVOIDING FAILURES. Sets which. have been 1011. fur seveial weeks in shops or homes and which include elect roly ic condensers should he gradually brought, back into operation if damage to the condensers is to be entirely avoided. This suggestion was made at a meeting of the institution of Radio Engineers, Sydney, by Mr J. Katzman, a visiting engineer from the United States, in the course of a lecture on the properties of mica, paper and electrolytic condensers. Air Katzman said that the set should bo switched on for a short period, then switched oil, then on again and off again until the periods cf operation and rest reach about 15 minutes. He said that it this hint was included in the operating instructions supplied with receivers there would be a decrease in the number of condenser failures. The lecture covered the whole field of condenser design and manufacture and' emphasised the necessity for paying attention to apparently small details if long, trouble-free service was to be obtained from these small but important components of a modern receiver. Electrolytic condensers which, because of their relative cheapness and compactness, were particularly suitable for use in certain parts of receivers were dealt with in greater detail. The construction of these devices, as in the case of other components, shows the great influence that the work of specialists, such as chemists and physicists, has in modern manufacture, for, if the device is to be a success, the materials used must be of the utmost purity. The fundamental principles of this typo of component were known 30 or 40 years ago, but troubles associated with the materials and the fact that until radio receivers operated from I nnwpr sunnlv circuits wore reciuired

in large numbers, the demand was small, retarded their development. Now they arc used in tremendous quantities and their use is increasing from day to day. Broadly, these condensers may be divided into two groups, viz., the wet and the dry or semi-dry type, but the fundamental principle is the same in each case. In other types of condensers one or more pairs of conducting plates are separated by some insulating substances, such as air, mica, or paper, and the condensers can be equally well connected either way round into a circuit. The electrolytic type, however, is polarised, which means that a single unit cannot be used in an alternating current circuit, while in a direct current circuit one

terminal must always be connected to the positive side. Further, the medium or dielectric between the two “plates” is of a totally different type. In fact, its precise nature is not known, although it. has received wide application. Many materials and combinations of materials have been tried in the construction of these units, but the metal generally used for the anode or the positive electrode of the condenser is aluminium, which is of such

purity that other substances present do not exceed a very small fraction of one per cent. The material, usually in the form of foil, is kept in a state of the utmost cleanliness, and is made up into an electrode of a suitable size and shape, and is then immersed in an electrolyte of any one of many suitable types or combinations of types and connected to the positive side of a source of direct current voltage for a period of about 24 hours. This results in the formation of a hard greyish coating which is of n peculiarly tough nature, resembling enamel in many of its properties. The pre-formed electrode is then placed within a case from which it is insulated and a quantity of electrolyte is placed within the container. The electrode forms the positive pole of the device and the electrolyte and the can form the negative pole. After tfie application of a further forming voltage, the device is ready for use. In the so-called dry type two sheets oi foil are used. They are separated by a porous substance which is impregnated with electrolye and the combination is wrapped up and placed in a container within which a small amount of electrolyte may be placed, the absorbent material between the two sheets of foil acting as a wick to draw up the electrolyte and maintain tho necessary state between the two electrodes.

Mr Katzman discussed thoroughly tho properties of these devices and pointed' out the necessity for avoiding overload and keeping the temperature of the device at a figure not exceeding 125 degrees Fahrenheit. In electrolytic condensers there is very much less margin between the operating voltage and the voltage which will cause a breakdown, but they have the very desirable quality of recovering from a momentary fault and being as good as ever after it, in which respect they differ from paper and mica types, which, when they break down, arc of no further use. — N. Al. Goddard, 8.E., in the “Sydney Morning Herald”).

RADIO AND SHOOTING STARS. Radio enthusiasts are aware of the importance of the electrical conductivity of the air at. heights above -Ki miles. Without this phenomenon long-distance radio would be impossible. The conductivity is mainly due to electrification of the upper air by ultra-violet rays from the sun. Nagaoka and A. M. Skellett suggested that some of the conductivity might be due to the impact of meteors coming into the upper air. T. Minohara. and V. Ito, of the Naval Experiment, and Research Establishment. in Tokio, have recently proved that this, in fact, occurs. These two observers were studying the echoes, or return of radio waves reflected from the upper air, during flic approach of the Leonid meteors to the earth in November. 1932. They found that the radio echoes were increased in stregth and rapidity in succession. The meteors form clouds of electrified' atoms, (lie smaller meteors being the most, effective at greater heights and the linger meteors at. lesser heights. These clouds of electrified particles can cause important irregularities in radio ' ram-mission.

BOYCOTT OF RADIO. GIPSIES ANNOYED. The gipsy fiddlers of Hungary, whose age-old tunes, with their sombre melancholy, are known to | many British wireless listeners, startled a, boycott of the radio recently, I says an English paper. | The tiddlers stated that they felt both insulted and exploited, and reI fused to appear before the microphone until their grievances were remedied. These were that the fees received from the Hungarian Broadcasting Company are inadequate, and that Dr. Andreas Spur has been appointed to the newly-created post of Commissioner for Gipsy Music. Twenty-two out of the twenty-four leading gipsy conductors and their orchestras joined (ho strike. The two remaining orchestras hardly sufheed to carry on the gipsy programmes. But, the aid of less-talented gipsy musicians is being invoked. Dr. Spur is an expert on Hungarian folk music. His main task in his new ‘post is to superintend the arrangement, of wireless programmes so that, duplication of items may be avoided'. It. has frequently occurred that different orchestras playing on the same evening have given the same melodies through lack of organisation.

Tho doctor has also been authorised to regulate, for broadcasting purposes, the musicians’ technique. The artistic susceptibilities of the temperamental gipsies are thus deeplywounded, and they are expressing their resentment of the new “gipsy dictator” by the only method open to them.

A'prominent gipy violinist said — ‘‘My father and my grandfather fiddled the tunes that 1 am playing to-day. I can bring tears to the eyes of my patrons, for my art is inborn. It is a thing of the soul, not something that may be regulated by academic principles.’’

“WIRELESS POLICE.” The British authorities concerned have taken cverj r possible step to guard against the use of secret wireless stations for illicit purposes. It. is claimed that no transmitter could be habitually used in England without being tracked down by what may be described as the wireless

police of the Post Office Department —a band of specially-trained engineers who have detector posts in various parts of the country, says the “Daily Mail.’ Recent disclosures concerning the operations of unauthorised transmitting stations in England have drawn attention to the ease with which anyone with the necessary wireless engineering knowledge can construct and operate a. transmitting station of sufficient power to roach almost any part of Europe. There has been no case yet reported' of the use of an unauthorised wireless station for anti-social purposes, but it is no secret that there

aro certain organisations in England which have in mind the use of wireless for the dissemination of propaganda'Should Great Britain at any time find herself in the grip of a general strike. These organisations would use wireless not only for fanning discontent in England, but also for establishing communication with Continental sympathisers. Secret wireless stations on the Continent. con’d also be used for propaganda purposes in England, but so far only the Moscow station has been reported to have been used for this purpose.

An expert explained to the “Gaily Mail” that the only form of transmitter in Britain which could hope to escape detection by the wireless: police for any length of time would be one which never operated from the same place twice.

“ft might be possible,” he said', “to equip a vehicle such as a pantechnicon with a broadcasting apparatus, but there would be great difficulty in maintaining a regular and powerful transmission with any degree of efficiency.”

RADIO LICENSES. THE NEW AGREEMENT. Within the'past week a. very radical alteration has been made in the conditions under which radio receivers may be sold in New Zealand, whether nianufacluied here or imported (says the “Dominion - ’). The listener’s license fee in New Zealand is 30/- per annum. Out of this the Post and Telegraph Department, which collects the lees, has paid 25/- per license to the broadcasting authority (formerly company, now board), retaining 5/-. Under an agreement with the Amalgamated Wireless (Australasia), Ltd., .”/- per license per annum has since 1927 been paid to that company in full satisfaction of all claims in respect to patent rights held by the company, involved' in the whole of the I rcadcasting service. A similar arrangement existed in Australia, and it has “kept the peace” in the matter of wirelss patent royalties since it was instituted. The old agreement, by abolishing all questions of individual licenses to manufacture, greatly facilitated the development of native radio industry, and in Australia, where the protective policy was powerfully cflectivo (the duty being 12/(1 per valve or 40 per cent., whichever was the higher) imported receivers are an unimportant factor. It had, however, the disadvantage that there were other claimants to royalties, having no share in the 3/- deducted from the listener’s license fee.

The new agreement in New Zealand' has not been published in detail. It has been stated, however, that it imposes u charge of 3/6 per “anode stream.’’ Most, valves have only one “anode stream,'' which means, of course, the flow of electrons from filament to plate; but. some have more. For instance, the recently introduced “double-diode-triode.” which is found in new receivers having automatic volume control, has three. Therefore, an up-to-the-minute receiver will carry a, royalty charge greater than 3/6 per valve, whereas sets not using the more complicated valves will be rated at 3/6 per valve. The rectifier valve, which usually has two anode

- ~ streams, is excluded and does not affect the royalty charge. It should be definitely understood that the royalty charge is not imposed upon the valves themselves, so that their cost is not changed or affected in any way. It is a method of recouping the owners of patent rights in receiving circuits, and is attached to the set as sold and not to any replacements or renewals of parts. The patent royalties in respect of. the valves (and other parts) are covered by the prices charged for

them. The arrangement will not affect sets already in use, or those available for sale within a brief period, but from June 1 all sets unsold will be subject, to the new charge.

While present owners of receivers will not be affected, future purchasers Will be called upon to pay higher prices for their receivers. Whereas the new system will apply to all new sets sold, the patent right owners will immediately lose the whole of the revenue derived from licenses foi sets issued under the old arrangement, and will thus lose heavily until the sales of new receivers i iiiid up a large new revenue. On the other hand, the Post and Telegraph Department will promptly begin receiving 3/- per license, a matter of well over £15,000 per annum. It has long been contended that the other 2/-, which is all the Department has retained, is inadequate to cover the cost of collecting license fees, keeping an eye upon “pirates” who listen in without paying, and conducting the radio inspection service. But nobody has suggested that the Post Office provides a service t 6 listeners worth 5/- per annum per license. It will be interesting to see whether the Postmaster-General will hand over part, of his new revenue to the Board (which, of course, will be glad to get it.) or . A good deal remains to be done in assiting in getting rid of artificial interference. And if is not unreasonable to suggest that some part of the new revenue might be earmarked for use in developing services in areas that the Board has hitherto felt unable to cater for. It is understood that the companies] which will share in the royalties! under the new agreement are A.W.A., Standard Telephones and Cables. Ltd., the Phillips Company, and the Ncutrodyne Proprietary, Ltd. (controllers of the Hazeltine patents).