NEWS AND NOTES

Radio Record, Volume I, Issue 13, 14 October 1927, Page 8

NEWS AND NOTES

(By

Switch

Mica is one of the most efficient in- ’ sulators known to science. If it re guires 100,000 volts to puncture porcelain 1 centimetre in thickness, mica of the same thickness would require 1,000,000 volts to pierce it. All home-builders of crystal sets should try placing a smiall fixed condenser between the two ’phone terminals. This generally results in rather stronger reception. A fixed condenser f .001 microfarads will, as a rule, prove the best. One stage of radio frequency amplification will greatly increase the range of a receiving set. A signal which is too weak to operate the detector valve cannot be amplified by audio-frequency valves, Never hold a lighted match near the tep of a wet’ battery. The gas given off by a wet battery is highly inflam-. able as it comes straight from the battery, but when it mixes, or is diluted with air, it becomes harmless. A good make-shift "carth’ can be fixed up by country dwellers who cannot obtain the use of a waterpipe, and is often in demand, A few yards of wire-netting, buried flat-wise about two vr three fcet below the surface will snake a good earth. The ground should be kept moist, .and-the wire running to the earth terminal of the set should be firmly soldered to the wire-netting. The latter should be placed right underneath’ the aerial if possible, but this is not at all essential. When using galena as a crystal detector the cat’s whisker wire may aiso be of silver or brass as well as copper. If you want something more aristocratic use iron pyrites, which requires a cat’s whisker with a gold point. Galena and a silver wire, however, take a lot of beating for sensitivity. , Cheap celluloid hatteries should he shunned. After a little while celluloid oatteries of the cheaper type commence to froth inside, and when on charge the froth comes out of the top so that the liquid is lost and this needs replenishmg each time. The effectiveness of an acrial is reduced if the resistance is high. Wighfrequency or radio-frequency currents flow on the surfare of a conductor, largely, and therefore the surface area of an aerial should be as large as possible. Therefore use a stranded acrial in preference to a single wire. It is wise to purchase a wet battery larger than appears necessary. It is better practice to fit an accumulator of ample size than one which has to be driven to ils utmost capacity. ‘Ihe former can be kept in perfect condition by numerous ¢mall charges, whereas the ander-powered battery will always have to be recharged to ifs full capacity and with great frequency. The inverted L, type of aerial is to be preferred to the T aerial, as it gives a ateater effective length for the same amount of wire. The effective electrical length of an aerial is the distance from the farthest point of the aerial wire to the place where the lead-in is attached, plus the length of the lead-in itself. With the T type of aerial the lead-in wire should be attached to the very centre of the aerial. The aerial wire and the earth act is two plates of a condenser, and the 1ir between them is electrically stress‘d whenever currents surge up and lown the aerial. If the earth conaection is poor, therefore, little energy s absorbed from the wireless waves. A great advantage in using a variometer for the tuning device of crystal set is that there are no ‘dead-end"’ effects in the variometer. Yo tappings or inductances are lecessary; there is also smooth and nfinite adjustment between minimum ind maximum positions, and the variometer is a robust mechanism. But get the correct-sized variometer jor most efficient results The purpose of a small fixed conlenser across the ’phones of ‘either a trystal or valve set is to improve the juality and strengthen the volume of eception. The condenser ‘s charged nd discharged periodically with tlie bulsating enrrents rectified tv th> deector. It likewise discharges eriodically into the ’phones. This rrangement gives a smoother note han could otherwise be obtained. Vield strength measurements made in he eighth radio district of U.S.A, by adio Supervisor S. W. Edwards lave revealed the now oft-confirmed act that location is of as great importance as aerial power in determining he service area of a broadcasting staion. ‘The most serious factor which revents equal radiation in all direcions from a radio aerial is the shadow ffect of large surroundigg masses of oth conducting and non-conducting 1aterials. (As the cost of transmitting istallations goes up, pottable transritters wil Ihe used to determine the haracteristics of any transmitting point fore a station is erected, It appears lat irregularities in transmission charcteristics, due to location, can be anvsed with a portable low-power transritter and that great increase of power oes not change the general nature shading effects. It is not unusual find that a broadcasting station of nsiderable power may serve only fifty seventy-five miles in one direction, t is easily heard four or five hundred another,

mam) — If the cell of a battery becomes ene. crusted with sulphation, this is du@ to neglect through letting the battery; . discharge too low, or through permite ting it to stand too long in an als most discharged condition. This hag a bad effect on the battery, but if the condition is not too aggravated the sulphation can be cured by subjecting the battery to a prolonged charge at a low rate of amperage. The difference between success and failure of a receiving valye set lied in the correct amount of B_ battery, voltage applied to the detector valve. The amount of B battery voltage om the valve must be correct for the nar« ticular type and make of valve useda ° Read the instructions which accompany the valve, and also experimen®€ for best results. The best method of connecting the gridleak depends on the valve itself, Some valves work more efficiently with a negative grid potential, while others require a positive potential. The usual arrangement with a single detector valve is to place the leak in parallel with the grid condenser and connect the positive L.T. to earth. For H.F. amplification it is generals ly correct to place the leak between the grid and negative L.T. In multivalve sets the detector valve has it leak placed between the grid and posix tive L.T., thus assisting rectification. Conversation by radio telephone bés tween a mail aeroplane pilot and a tes# station of the United States Bureaw of Standards at Bellefonte, Pa., U.S.A.s has been successfully maintained over, distances of 150 miles, it was stated res cently in a Commerce Department res port. A little while ago the Americans des cided to substitute the word ‘radios cast" for. "broadcast,’? and the idea was largely adopted. Lately, however, the word "broadcast" has been re adopted by many papers, owing, probably, to the euphonyv of the word ag compared with ‘‘radiocast." Some concern has been expressed at Washington over the information that Cuba contemplates commissioning a number of high-powered stations that might cause trouble to broadcasters on the Southern and Eastern coasts of the United States. This question also will have consideration by the October In ternational Radio Conference. Advertising through radio announces ments over Station WGL (Secancus, New York State) costs 47.50 dollars (£9 10s.) for twenty-four announcements of 100 words each, according to a contract which the Theatre Sales Company says it made with the Inters national Broadcasting Company. On September 1 the well-knowrt | Yankee radio station, WGY, Schenece tady, announced that the Federal Radio Commission had permitted it td use 100,000 watts of power in tratise mitting its regular programmes, be ginning that evening. The station has beeit experimenting with th¢ superpower for some time to deter mine whether the increased outpud would interfere with other broadw casters. A peculiar blanket on short-wave ré4 ception was experienced in the North of the United States from abong August 19 till August 22. A repre+ sentative of the Radio Corporatiox§ said that the peculiarity was due tod the Aurora Borealis, Nothing could bé heard of short-wave transmissiot, in the Northern Hemisphere, Eveti the Marconi beam traffic between Eng» Jand and Canada had to be diverted.

‘was one of the few operators to hold NEW SHORT-WAVE STATION Another short-wave broadcast station, 2XBH, transmits now simultaneously with broadcast’ station WCGU, Sea Gate, Long Island, U.S.A. The wavelength of the new transmitter is 54 metres. The chief radio engineer of the station is Mr. Jesse Holland, .who consistent communication with Donald MacMillan’s vessel, the Bowdoin, during the explorer’s voyage to the Polar regions in the summer of 1925. INTERNATIONAL RADIO CONFERENCE The question of the distribution of votes at the International Radio Conferetice being held in Washington, U.S.A, this month, was raised recently through the contention of the German Government that it should be accorded the six votes it possessed at the International Telegraph Conference in London, in 1912, . Other Governments pointed out, howtver, that in 1912 votes were based on the number of colonies possessed by each power, that Germany was deprived of her colonies at Versailles and that consequently she should have ‘but one vote at the coming conference. This basis for the distribution of votes is disputed by Germany, which contends that colonics were used artificially as criteria for the distribution of votes, but that in reality votes were distributed on the basis of the economic power of each nation. 696 YANKEE STATIONS On August 29 forty United States broadcasting stations which had so far failed to apply for renewal of Licenses that expired on August 14 last were notified by the lederal Radio Commission that unless they applied by September 6 for authority to continue on the air their names would be deleted from the Government list. ‘This means that the stations involved would be liable to prosecution if they operated after the date named without a Jicense as required by the Radio Act of 1927, Iixactly 696 American stations are now on the air and all but forty have received new sixty-day licenses dating from Angust 14. It was understood the forty delinquents were miostly small stations, many of which, officials in Washington believe, were ready to retire from the broadcasting field. INTERNATIONAL BROADCASTS INGLAND AND AMIRICA, | Captain Peter P. Eckersley, Chief Engineer of the British Broadcasting | Corporation, announced on August 23 at a luncheon in London that he intended to visit the United States: in September to begin negotiations which he believed would result within a year in a regular exchange of English and American radio broadcast progranimes. Eckersley’s announcement, made at a luncheon of the Radio Manufacturers Association of Great Britain at the Hotel Metropole, London, was relayed to New York by radio telephone and received by American radio men breakfasting in a New York apartment. The engineer will be followed to America in November by Sir John Reith, Director-General of the British Corporation, who will make final arrangements with Merlin H. Aylesworth, president of the National Broadcasting Company, and David Sarnoff, general manager of the Radio Corporation of America. INTERFERENCE FROM MORSE SHIP KOQUIPMENT BLAMED. Steps will be taken by the American delegation to the International Radiotelegraphic Convention, being held this month in Washington, U.S.A., with a view to effecting an agreement that will protect land broadcasters from interference caused by radio operations at sea. The interference of sea radio with land broadcasters is due, in the main, to the style of equipment used aboard most ships, and this is a matter that requires adjustment by international agreement. Complaints have been made to the Federal Radio Commission that sea signalling is causing substantial interference at times with broadcasters on Long Island and at other points on the North Atlantic, as well as along wide stretches of the Pacific Coast. The commission is powerless to deal with this situation without concurrent action on Se part of other marine nations involved. Through Admiral W. H. G. Bullard, its chairman, who has been named a delegate to the October conference, the commission will emphasise the need for international regulations that’ will eliminate the marine interference with land broadcasting, All that is necessary, officials in Washington say, is for the nations concerned to require their ships to install modern eaninmentk.

THE LOUDSPEAKER FIND ‘THF BEST POSITION. It is always a good idea to experiment with the position of a londspeaker, Quite frequently the arrangemeut of adjoining rooms in a house has the effect of producing annoying echoes, and the horn must be tried in several places before satisfactory acoustics are obtained. If the loudspeaker is too near the ceiling, as when placed on a piano, the sound waves will be deflected @wnward on the listener’s head, and speech or music will sonnd decidedly unnatural, Similarly, if it is put on the floor, the sound will hit upward. Music will always sound better if the horn is kept well away from where the listeners sit. A jazz band will never sound clear if the londspeaker is put on a dining-room tab.c. If powerful amplifiers are employed, the radio listener cannot expect pleas‘ant reception, any more than he can f expect a drum to sound pleasant if he sat right next to it. TO MAKE SPAGHETTI The red, yellow, green, or black insulating covering on the wires inside a receiving set is known as spaghetti. To manufacture your own spaghetti, a piece of wire that is to be used in wiring mp the ‘set shonld first be straightened out; a two-foot length will be sufficient. A large sheet of good, light grade white paper should then be bought; twenty inches wide will be the right size, Strips just wide enough to encircle the wire twice should be cut from the sheet; each strip will then be twenty inches long by about one-half an inch wide. Paper As a Substitute. This strip of paper is then wrapped tightly around the piece of wire and tied in two or three places with string to hold it solid. Some paraffin is melted in a pan, and with the aid of a spoon the entire length of the paper on the wire is given a good coating of the molten paraffin. When the paper is dry the strings may be removed, and the wire pulled from within the paper tube. The finished product will have good strength and also will stand a heavy voltage without breaking. RADIO TRANSFORMERS Amplifiers are divided into two main Classes: Those designed to amplify speech and music directly, or audiofrequency amplifiers, and those for much higher frequencies, known as radio frequency amplifiers. The design differs quite widely between these two. Thus an audio-frequency transformer always has an iron core, made up of laminations-thin sheets-or of soft iron wire. This construction is to reduce the losses in the iron. A radio-frequency transformer, on the contrary, has an air core or a_ core of iron filings. A second marked difference is in the number cf turns of wire used. An audio-frequency transformer has several thousand turns on the primary winding, and from three to ten times this amount on the secondary. A radio-frequency transformer for frequencies from 600,000 to 1,200,000 (wave-length from 500 to 250 metres) will have only a few hundred turns on each winding. BROADCAST REPORTERS NOVEL AMERICAN ENTERPRISE. In Amerféa the broadcasting companies are commencing to organise staffs of reporters. WGL (Secaucus, New York State) the radio station that plans to appoint ‘official reporters" in various parts of the city and State, said it had received many telephone calls from listeners who desired to be enrolled at once on the list of news gatherers. By this staff of "‘reporters,"? WGL expects to receive news events from eye-witnesses as soon as possible after they happen. If a news event should be stupendous enough to warrant breaking in on a programme to give it to the listeners, WGL will do so. Charles D. Isaacson, programme director of station WGL, announced recently that the station plans to organise a staff of voluntary "radio reporters" to telephone events witnessed by them to the station and obtain connection with a microphone for immediate broadeasting. "We would like to hear from our listeners who would care to be designated as WGL official radio reporters," he said. "Those who wish to co-oper-ate will be given a number, a method of identification to eliminate any possibility of mistake or misunderstanding. Radio reporters who happen to be at or near an accident or crime or any event of importance not expected to happen will telephone to WGL and at proper identification, if the news sounds worth while, will be put immediately on the air by means of a plan we have developed of breaking into a programme,’