THE WIRELESS WORLD.

Otago Daily Times, Issue 21213, 19 December 1930, Page 5

THE WIRELESS WORLD.

NEWS AND NOTES,

By Magna Vox.

Items of local interest are invited by the Magna Vox" for publication in this atrer column. It is necessary that such matter varif should reach this office by Tuesday of the each week for insertion on the following broa * nday. detei __ ■ Metres. esser - 7ZL, Hobart 535 low-1 3AR, Melbourne 484 the 4YA, Dunedin .. .• «, 463 oscil 2FC. Sydney 442 WO ul 2YA, Wellington 420 meet 4QG, Brisbane 385 tectc 3LO, Melbourne . 371 ever 2AB, Sydney .. 310 j n a 2KY, Sydney 280 of e The 4ZO CHILDREN'S HOUR. a v; ■WELCOME. high The following is the nineteenth list of circi new members who have Joined Uncle Ben’s aero Happy Radio Family and will shortly w uv receive their badges and certificates:— Kevin Kean, Maclaggan street; Alice ? Brown, George street; Muriel Potter, High street; Jack Vincent, Prince Albert road; ? erl Violet James, King street; Pat Williamson, ing George street; Amy Walker, Surrey street; closi Grace Adamson, Main South road; Tom- fV.es Altcheson, King Edward road; Jean Wilson, „„_ + Tomahawk; Ted Barsdale, Albany street: Ivy Brown, George street; Arthur Dlcklnson, Dundas street; Jean Peters, Cargill turn road; George Bain, Grove street; Eileen emp Wltherstone, Opoho; Alfred Browning, and Wesley street; Rene Cuthbert, King street, to • BIRTHDAY GREETINGS. the' Lola Webb, 46 Kirkcaldy street; Jock nuei Buchanan, B 3 Sutherland street; Nancy 2„r, Demolln, Mornlngton; Peggy Brooks, 19 J Princes street, Musselburgh; Joe M'Qeorge, 01 56 Hlghgate; Allan Gill, 13 Chapel street, P r « Kalkoral; Eileen Gray, 77 Carson street, thei Mornlngton; Mr Dale, 107 Harrow street. is < sucl THANKS. call Uncle Den desires to sincerely thank all new members and friends who have sent In f rol reading material, etc., for children In the Hospital, also all those who have forwarded Tv donations In connection with our Christmas tree and party. Further help la required, vab and donations will be thankfully received by fori Uncle Ben, care of 4ZO, Octagon, Dunedin, CHRISTMAS GREETINGS. Aunt Alma, Uncle Ben, and all the staff ' v of Station 4ZO extend our best wishes to all members of our Radio Family and their con parents, . Also to all friends who have Y ea helped our sessions In any way whatsoever, the May you all enjoy a very bright Christmas fees and a prosperous New Year. mel r ■ ■ A n THE PARTY. Members of the Family are all Invited to to • the Christmas tree and party, which will be „f held next Wednesday afternoon (Christmas “v. Eve), December 24, from 4 p.m until 6 p.m., ? , and will take place in the Riviera Tea oal Rooms, Stuart street. The children’s session to will be broadcast from, the party. Ad- Wi mission tickets are free to members, and vid may be obtained, by writing or calling, from r,fV, Station 4ZO. All correspondence In connection with the 4ZO children’s hour should . be addressed to Uncle Ben, care of Station li 1 ■ 4ZO, Octagon. Dunedin. Ly LETTERS RECEIVED. Oci Owing to the above announcements appear- 425 Ing to-day no letters from members will be exi published In our column, but Uncle Ben 1 cor would like to thank the following, who have sent In letters:—Douglas Hunt, Johnston , street, Milton; ’ Nancy Dale, 107 Harrow street; Mrs A. M. Connor, 90 Forth street; IDe Audrey Duncan; Kevin Kean 29 Maclaggan its street; Marjorie M’Parlane, 17 Douglas street, wa ’ St. Hilda; Phyllis Mathewson, 15 Loyalty a d( , street; Isa Allan, 52 Prince Albert road; Eric D _ Saunders, 14 Harbour terrace, Ravensbourne; • Evelyn Webb. 10 Marquis street, North-East ers , Valley; Alfle Mills, 28 Rawh.lt! street. Sun- ass I shine; Hlnerua and Clarence Adams, 7 Lees I ini , street; Keith, Audrey, and Finlay Constable, so - 4 Longwood avenue, Mornlngton; Rene. CutU- IDi bert. King street.—Kla Ora, everybody, Co] UNCLE BEN. C J V '» • ta: . ANSWERS TO CORRESPONDENTS, po t A. C.; Kaikorai Valley.—l am afraid I q could not give you an estimate with- ca out knowing something of the value * and the care with which the power transformer has been designed. It is JP not likely , that the consumption tK a could be more than 60 watts. This 3 would mean about 16 hours for the f. ' cost of one unit. ■ I tl( B. R. M‘P., Dunedin.—The noise is due n to microphonic values, the ' sound 6t,] ;- waves from the loud speaker causing eT j e the element in the tubes to vibrate. ) vJ a Try turning the loud speaker away na from • the receiver, which should be £ x placed on shock-absorber sponges for p le feet. If the noise is very bad, the . ( detector valve is ' probably to blame :s and a change might help. Si ’ “Neutraliser,” Mosgiel.— (1) The' object -I" of neutralisation is to prevent oscil- J or ' latiqn, the neutradyne being a 1 PI r, receiver that does not oscillate. (2) ™ ” You could use a condenser with a 1)1 2- breakdown voltage of about 500 in ar r . series with one of the main m leads. - Another method is to use a ™ 1 copper plate insulated from a metal °‘ ' chassis (a capacity aerial). There " is is a slight hum on an electric I re receiver at all times, and the use of I [I the mains line and series condenser 1 I may make this stronger. The earth ] 1 ce is _ usually a capacity one, though the 1 I eliminator is indirectly earthed I } s through one side of the mains. Many 1 r j. of the sets are directly earthed. 11l ill • i 8 AMATEUR TRANSMITTERS, df At a special meeting of the ’ Otago { ' branch of the New Zealand Amateur i j" ’ Radio Transmitters’ Association Mr T. 11 Qe Clarkson (Auckland) was re-nominated I I for the office of president of the New Zea- 1 ■at land Council, and Mr J. T. Callander r ,] v (Dunedin) elected vice-president and 1 Otago representative. * I I ld . RADIO AND NAVIGATION. L The announcement is made from the 1 offices of the United States Lines that I I el- they will soon introduce in their trans- 1 ad atl antic liners a new weather information I by service in the form of charts which will I lm be sent by radio. The service is being 11 v. introduced by the Radiomarine Corpora- I . tion of America, after experiments in the 1 113 transmission of charts to an Atlantic 11 liner. Recently a chart issued in New’ I we York was successfully received by tbe I I d commander of the America, off Fastnet, j when on a voyage to New York. The ] chart showed high and low-pressure areas, j I A. barometer readings, direction of winds, I nd fog banks, and other information valuable I ap. in navigation. The radio equipment on I r ol. board the American liner has been used ] . ' for various experiments by the Radio- I ; ne marine Corporation. These have included 1 D’ - the transmission of a part of a New York an- newspaper. It is stated that an endeavour rly is being made by the United States Lines ■se, to develop this form of service to enable me Passengers to see a replica of a newspaper . published in New York while they are )n ' crossing the ocean, ive j. ds ’ UNLICENSED RADIO. 7 Forty prosecutions against householders rcI J for having in their possession unlicensed cal wireless sets were heard before Mr E. C. md Levvy, S.M., in the Invercargill City xu- Police Court. Senior-sergeant Fox, who n ( s conducted the prosecution, stated that the _ Post and Telegraph Department requested ? that the court’s attention be drawn to the isiy regulations whereby it is illegal to operate lan any set without a license, seven' days only and being allowed in the case of a dealer who ndy has a set for demonstration purposes. The j n . department was pursuing a vigorous policy ilsn insisting on compliance with the regulailso tions. Several explanations were adrea- vanced' by the defendants. In many ges. instances it was stated that their boys rec- had made the sets, but had obtained no give results. Others stated they had the sets on trial, but admitted they had had them , , for more than seven days. A large pro- ' * s portion of the persons prosecuted were actc owners of crystal sets, capable only of im; local reception. I int; “ It seems that many crystal set owners or ” consider they have a grievance. It-may v \ . be they have r well-founded grievance, ;’ ’ but that is bt-s-de the point at present ” ~ rr ? remarked his Worship, when counsel in na s one 0 f fj ie f ew defended cases said that and the greatest trouble arose not from mne crystal sets, but valve sets which, although Dol- not registered, could receive broadcasts from all over tbe Dominion and beyond, PP “I detest the jolly things. My boy “ ls had it and when the inspector called and solos S aid a license must be taken out I did i on away with it,” declared one man in anlute other case. Dol- “It might have been better to let the ssj- boy have the set,” observed the magisy. lx trate, when the defendant said he let this ni jy* boy have a set in the first place so as to coils keep him in at nights. It was also stated lute that the crystal set was labelled “no men license required for this set,” this being rge’s contrary to the regulations. r£,,. Most of those charged wore ordered ,i lk ' to pay costs (10s). MorDETECTORS AND AMPLIFIERS. ■p . The electrical variations representing ” air speech or music have frequencies ranging between 25 and 8000 or 10,000 cycles *

. i second, and these are conveyed across the space intervening between, the transmitting station and the receiver by means of a radio-frequency wave, that ifl, by a “carrier wave” whose frequency ia greater than 30,000 cycles a second or bo. For a wavelength of 300 metres the radiofrequency involved is 1,000,000 cycles a second or 1000 kilocycles a second, the frequency being inversely proportional to the wavelength. The amplitude or strength of the high-frequency wave is varied or modulated in accordance with the wave shapes representing the matter broadcast. Every receiver possesses a detector or rectifier which performs the essential function of separating out the low-frequency electrical variations from ■the radio-frequency or carrier-frequency oscillations. Without this separation it would be impossible to operate any electromechanical reproducing device. The detector thus really forms the nucleus of every receiver, and one of the first points in designing a receiver is the: attainment of efficient and satisfactory rectification. The efficiency and general performance of - a valve detector depend to a very large extent on 1 the value or amplitude of the high-frequency voltage applied to its grid circuit. In general the voltage developed across the tuned circuit associated directly with the aerial is too small to enable the rectifier valve to function properly if the latter is connected directly to the tuned aerial circuit. Only when the station being received is powerful and moderately close is satisfactory rectification under these conditions attainable. For the reception of distant stations which produce extremely feeble oscillations in the aerial tuning circuits one or more valves are employed between the aerial tuning circuit and tee detector valve in such a way as to produce high-frequency voltage oscillations of greatly increased amplitude at the grid of the detector; the high-fre-quency oscillations are virtually, amplified before being applied to the grid circuit of the detector, but it will oe presently that the energy represented by these oscillations of increased amplitude is drawn from a local source of supply such as a high-tension battery. Tbe socalled amplified oscillations are really a new set in a separate circuit quite distinct from those in the aerial circuit, but are controlled by the aerial oscillations through the medium of the amplifying valves in such a way as to have the same form and frequency. A PECULIAR SITUATION. When the Federal Government took control of broadcasting in Australia two years ago assurances were given that all the money paid by listeners for license fees would be devoted to the improvement of transmission .and programmes. An arbitrary division was made, and of the 24s per license fee 12s was allotted to the contracting company for the supply of programmes, including management, office rents, and other expenses. Of the balance tbe Post Office Department was to pay the royalty fees to Amalgamated Wireless, Limited, for patent rights, provide transmission stations, land lines, and other facilities, including experimental work for the improvement of broadcasting in Australia. The Postmaster-general (Mr 1 Lyons) in the House of Representatives recently stated that from July 17, 1929,.t0 October 31, 1030, there were issued 422,102 listeners’, licenses. These figures i excluded where the contracting * company (Australian Broadcasting Com- | pany. Ltd.) did not assume control until J December 14. After the Poet Office ; Department had paid all charges against 1 its moiety of the 24s per license fee, there . I was a balance of £70,000. This money, r added the Postmaster-general, has been I paid into the Federal Treasury. Listen- [ ers are perturbed at this action. The . assumption is that the money has gone 3 into the Federal revenue accounts and .so is lost definitely to broadcasting. ■ Different organisations are giving serious consideration to the matter, so as to preclude the possibility of listeners being taxed for the raising of revenue for purposes other than the provision ot pro--r grammes - and the .development of broad- . casting' in Australia. Under tbe terms » of tbe contract made between the Post I Office Department and the Australian a Broadcasting Company, Ltd., 16 relay sta- , tions were to be erected during the curB rency of the contract, which expires in » 18 months from now. The only relay station yet erected is that of 2NG (Newe castle), and the datt? of its opening. is j still indefinite, despite the fact that the e engineers of the Post Office Department, , who undertook the, erection of the station, ' have had several consultations with the a expert' whom the contractors sent I**® r London to assist the official experts. The e Postmaster-general now announces that it ■ p is expected three more relay stations will be completed within the next nine months, t No information is available as to when, [. or where, the remaining 12 relay station* a promised are to be erected. Hence, tbs ) whole position regarding the future of a broadcasting in Australia is uncertain n and unsatisfactory. Protests are to be n made to the Federal Government upon this a matter by representatives of listeners and ot the radio trades, e *— ■ - '