NOTES AND COMMENTS

Radio Record, Volume I, Issue 40, 20 April 1928, Page 8

NOTES AND COMMENTS

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ps America "RP" batteries are still greatly in vogue for short-distance reception, as the eliminators have certain disadvantages for short-wave work. The best eliminators frequently intrude a background of hum on short-wave reception, though inaudible on the ordinary broadcast receiver. A CORRESPONDENT writes to the "™ New York ‘Radio News," kicking against the extension of the chain system of broadcasting. He says: ‘Nightly there are 25 stations in one chain. Formerly, we had a diversity of 25 different programmes from those stationswho cares whether it is the highly-paid artists from New York that entertain us? . Many times I ‘have thonght that undiscovered nincompoops provided better entertainment, than those headliners played by ‘the cliains. Let freedom of the air go unchallenged. I’m sorry Iam not a business man, but I am down among those wage earners where money counts." ! TO prevents its scaplanes, when forced down in flight, from being without means of communication, the . United States Navy will equip them with shortwave’ transmitters having hand-driven generators for .an emergency. The standard frequentcy will be 8770 kilocycles, corresponding to 34.19 metres. JN Gothenburg, Sweden, a new solution for the apartment-uouse aerial problem has been found, by the suspension of a metal ring iu the courtyard of a muitipie dwelling. It is held tightly by steel wires; and the radio aerials, to the number. cf fifty, are attached to it-hy insulators, of courseand to the tops of the neighbouring roofs, Each is of the ‘T-type, with a lead-in from the centre} and the assembly is said.to resemble a gigantic spiderweb., "A charge of about £1 is made for connection to this system. Incidentally, it may be said that the Iuropean customjof depending upon one station for entertainment, as only the local can be received consistently with trystal sets, probably . makes for less irterference than would be thus cansed in ‘an American apartment neighborrheod. A FAN who cttenpts to ase the audio = circuit of his radio receiver as an amplifier for phonograph music often finds it inconvenient to remove the detector tube each time he desires to insert the plug from the pick-up unit in the detector socket. ‘his may be avoided by mounting an additional yacuum-tube socket on the baseboard of the set, and connecting it in paraliel with the detector socket. With the recciver arranged in this manner, it is necessary only to turn out the filaments of the detector and R.I’. tubes, by means of a rheostat on the front panel, and irsert the plug from the phonogranlt in tie extra socket. . ' At Zeesen, about 2) miles south of " Kerlin, Germany, a broadcast station was recently opened, capable of transmitting with an aerial power of 120,000 watts. ‘Ihe aerial is hent with a fixed tension by a heavy weight hung on pulleys. ‘he wave-iength employed is 1.260 metres. A, VACUUM-TUBE trai smitting set "™. using a small amount of power, and operating on a wave-lengtii of 7500 metres, and five receiving sets, responding to only one wave-lungth, control the street-lighting system of Glens Falls, New York Siate. Street lamplighters in that town, like a buggy-whip socl.et on an automobile, are now out of date. A low-powered valve transmitter, not very ‘dissimilar to the transmitting sets that ‘bring music and sp2ech to our homes, feeds a carrier-current or radiofrequency wave along wires leading to the receiving stations. ‘There radio receivers tuned to that singie wave-length, or fréquency, respond to the radio wave and, in turn, electric switches are tripped, relays operated, and street lamps lighted W ELSH members of the Engtish Parliament have rnited in a demand on the British postmaster-general for the establishment of a hroadcast station in Wales, devoted excinsively to programmes in the Welsh language. It is represented that this would be a great stimulus to the sale of radio'sets in Wales, as well as of cultural value. THE filament of a valve is desigued to give best results at a definite voltage or current, and at this value, a certain length of life for the filament is obtained. If the valve is operated at a filament voltage higher than the rated value, the electron evaporation is greatly increased, with little, if any, useful gain ; but the life of the filament is very greatly reduced. Some filaments do not actually burn out when the voltages are but they become ‘‘deactivated’; that is, the useful material has disappeared from the surface of the filament, ‘This may often be restored by turning on the valve with somewhat above normal voltages on the filament, and with the plate (‘‘B’’) battery temporarily disconnected; but prevention is much easier than a cure, WAY to eliminate A.C. hum caused by nearby socket-power and other electrical devices, is to shield the tronblesome wire with sheet tin or leadfoil, such as comes with friction tape. Cut it into lengths, two inches wide, and wrap the wire with it; then wind over the foil a length of No, 18 bare wire, which is connected to the ground,

qT" is reported } 7 the Me-vourne ‘‘Lis-tener-in" that ‘Station 2BL has engaged Gordon Ireland, one of New Zealand’s most popular radio entertain. ers, for a series of appearances. Mr. Ireland, who was one of the first artists , to broadcast in the Dominion, is a versatile entertainer at the piano, specialising in comedy, dramatic, popular numbers, and character sketches. For six months he was w.th the New Zealand Broadcasting Co., Ltd., at its Christthurch station, 8¥YA, where his work’ earned him a Dominion-wide reputation. ‘Ie will make his initial debut to 2B, during the ccming week." Se pus object of soldering is to unite © metal surfaces by means of a ‘ead-tin alloy, called solder. In some’ work, such as tinsimithing, metals are soldered merely to fasten thei together mechanically. In most electrical work, soldering is done, not only to fasten two metals together mechanically, buf also to exclude air and moisture, and provide a joint which offers a very low resistance to the flow of current, and -- which continues to do so for an infinite Jength of time. The melting point of soluer depends upon the proporticns of lead and tin in its composition. ‘Hard solder" is an alloy of zine and copper, which melts at a dull red heat.’ "Soft solder" contains various propoitions of lead and tin, end melts at a much lower temperature. ‘The solf.r used most, in electrical work consists of lead and tin in equal proportions, and is commonly known as "half and half." It can be | obtained in bars, wire, or ribbon. AN unusual scene was staged recently in a London courtroom, when. alarge instalment house dealing in radio and other equipment brought suit against 541 of its customers, who had entered into ‘‘hire-purchase’" agreements, for balances due, varying from five shillings up to five pounds. Judgments were given by the presiding Magistrate for payimeuts in monthly amounts, varying fron two shillings up, according to the circumstances of the defendants. BRULLDERS of radio sets usually wish their panels engrayed, ro make a neat appearance, and give the cabinet a professional look. A simple method of doing this is to mark the arrows, letters, or whatever is to be engraved, on the panel with a lead pencil. A prickpunch with a sharp point is then used to go over the lines drawn, tapping lightly. With a little practice, these punch marks can be made to give the panel a fine appearance. ‘The small holes can be ijilled with engraving enaniel or whiting, or left as they are. Ts order to obtain long life and satis. factory service from rectifiers and condensers of the electrolytic type, it is essential that nothing but pure distilled water be added to the electrolyte. This rule is just as essential in the operation of electrolytic cells as in the case of storage batteries: for. if city water from the pipes in -the house is used, the mineral contents may cause a chemical action, which will destroy the efficiency of the unit. I IKE most neglected things, the grid4 teak is a most important adjunct to the circuit, and, correctly handled, provides a systematic control over the reaction, If the leak is of too small a value, the reaction coil cannot be approached to anything like close coupling without the set going into oscillation. On the other hand, if the value is too high, it will be found that the set will 80 into oscillation before the signal strength has reached its maximum. Between these two extremes exists the ideal setting. A variable grid leak is almost a necessity in most modern cit cuits. ‘The majority of listeners-in, and even a number of exnerimenters, take the value of the grid leak too much for granted; a fixed leak can only give complete satisfaction under exceptional circumstances, ‘i‘he only solution of the difficulty lies in the use of a variable unit, one having a range from 500,000 ohms tq five megohms being recognised as, covering the requirements of most Valves. .

"N Dr. Alexanderson’s system of tele-: vision recently demenstrated in America, there is a reyolying disc at the transmitting end, and a revolving disc at the receiving end, both driven by motors. When the receiver is first | started, the speed of its motor is far below that of the one at the transmitter, and the resultant image is a straight line of Tight. As the motor is ; brought nearer and nearer tn synchron:ous speed, this line of light breaks up into a series of parallel lines, slanting first one way, and then the other. Then there appears a distorted image of a face, again breaking up _ into splotches of light and dark. Tinally, when the two motors are running in synchronism, a true image may be scen on the lens. YT is seldoin that such brcadcasters as KDKA, Pittsburgh, and others west of the smoky city sign olf Lecause of an SOS. But the fifty-two transmitters nestled in the metropolitan area of New York go off the air immediately; because the big transmitter known as WNY, at Bush Terminal, in Brooklyn, N.Y., or that of NAHI, at the Brooklyn Navy Yard instantly endeavours to calm the cther, and establish communication with the ship in distress, or with other vessels in the inmimedciate vicinity. A 2-kilowatt "spark’’ iransmuiter is used at such times, because it radivtes a t4ateh broader wave than a yacumin-tube entiit, and, therefore, is more likely to be intereepted by a greater number of stations when it broeadeasts "ORT (stop transmitting), ship in distress.’ | | EP the United States, a group of phil- | anthrépists is at work on a plar to offer free of charge to every school in the United States. the broadcast services of pre-eminent teachers to assist in the work of the faithfnl resident teachers. Lor good measure, it plans to add music and taiks of outstanding national leaders, men and women who are making history. Leading educators are co-operating in the movement. With such prospects in view. snd with radio receivers available everywhere, it is ne wonder that schools are hurrying to install equipment. (One located in Brooklyn, adjacent to New York city, is considering estimates for installing a master reeeiver with eighty loudspeakers in the classrooms. A MODERATELY powered amplifier, | * using yvalyes of the 112 or 171. type, with pilates supplied from a 150 | or 186-yolt source, can, in most circum. stances, give results that will satisfy the most critical, The main advantage to be expected through the use of higher power is a gain in volume, and the increased realism that comes iu having, let us say, the volume of an orchestra, as it comes from the speaker, equal or exceed that of the orchestra itself. How- | ever, it is obvious that tle average setowner is not desirous of having a twen--ty or sixty-piece orchestra going full alt in his or her livine rnom., In a small room-and matiy rooms are small nowadavs-this would be unpleasant, even painfel. ‘Therefore. an amplifier capable of giving this volume could seldom be uesd. TOIL, leads from tie wet battery, wheiher it be ‘A’ or "B," will soon lie across the vents and become impregnated with the clectrolyte and eaten away. When the battery is on charge the spray rapidly eats into the battery leads, One method of preyenting such corrosion is te soak the leads for about a foet cr two of their length in melted paraffin. For this operation a coffee can placed upon ;the kitchen stove is very satisfactory ‘in impreguating the leads. ‘The first ‘one or two feet of the wire is simply ‘erammed into the can of melted para‘ffin and allowed to remain for several minttes for sufficiert penetration. COATING radio valves with paraffin is an easy method of silencing microphonic noises and other disturbaneces to which some are subject. To shield valves by this method it is necessary only to heat a little paraffin, bringing it to liquid state. Pour it immediately into a small jelly glass, filling the glass to a depth of about two inches. Hold the valve to be coated by the base and insert it upside down into the glass. The displacement will cause the paraffin to tise, thoroughly coating the surface of the glass. Care should be taken not to allow the paraffin to rise beyond the top of the base. Withdraw the valve and allow any drops to fall back into the glass. This coating will quickly harden, after which the valye should be dipped again. Should any of the paraffin get on the base it may be scraped off with a knife. Do not let the paraffin get too hot. It should be poured from the pan into the glass as soon as it reaches a liquid state, and allowed to stand in the glass a ninute or so before | dipping. A UT HOUCH European, listeners are x held strictly to payment of a fee for the privilege of owning receiving sets, in Bavaria they are allowed a. week’s free trial of a set purchased on approval, without taking ont a license. In England, however, the radio magazines complain, a number of public functionaries sccm to be of the opition | that it is an offence against ithe law fo purchase a radio set without having a license in advance, his places radio ] apparatus somewhat in the category of revolyers and narcotics. Reasonable latitude is permitted in New Zealand when a prospective buyer is using a set for a few days merely on trial.

HE well-known phenonemon of "body capacity,’? which every builder of a radio set has encountered, may be employed for the purpose of detecting the intrusion of a human being into the neighbourhood of radio apparatus; but it is not necessary that any of the instruments should he in the immediate vicinity of a safe which it is desired to guard. It is necessary only to haye a wire running to the safe, and another to the ground; or any large insulated sheet of metal may be used to create an electric ‘‘atmosphere,"’ which cannot be entered without upsetting the balance of the system and giving an electric signal-which will operate a relay and set off bells or an electric siren, turn on lights, or otherwise give warning as desired by its constructor. The radio burglar alarm ‘‘sees in the dark,’ so to speak; it is much less expensive than the complicated maze of wires now wsed for electric protection systems; and it transmits its warning to the guards, watchmen and police, who will answer its summons, without apprising the intruder of his danger until it is too late. A CORRESPONDENT writes to the +*% New York "Radio News’: "With reference to the recent catastrophe, the loss of Mrs. Frances Grayson and companions in her transatlantic *plane, ‘Dawn,’ I would appreciate it if you would publish, in your excellent magazine, a suggestion io future transatlantic fliers, and the general public, regarding the danger of inadequate radio equipment, heretofore used on transatlantic flights, and lack of trained radio men, which is partly responsible for the complete disappearance of several ‘planes and their occupants."’ OX of the most rigorous tests to which a loudspeaker has ever been subjected was recently performed in New York City by engineers of the Bell ‘Telephone Laboratories, when they installed a giant speaker on the roof of a thirteen-story building on the New York side of the Hudson River for direct communication with the Jersey shore, which is over a mile distant. Engineers on the opposite side of the water heard both music and voice reproduced with enormous volume, but without distortion. The horns nsed wert of the new "exponential" type. THE "SOS" has more than once of late called shipping to the assistance of aviators; the compliment was returned in the Inglish Channel not long ago, when the pilot of a LendonParis aerial) express observed that a small steamer below him was on fire, He at once used his transmitter to notify Croydon, England, which broadcast the alarm. It was picked up at Boulogne, France, from which port a tug at once put out, rendered timely aid, and towed the distressed vessel with her ercw of fifteen safely into port. [* is often diflizult to locate holes for mounting condensers and other instruments without a template. | A very simple way of doing this is as follows: ‘he shaft hole is located first, and drilled, The condenser or other instrument is then placed on the panel with the shaft through the hole, and the condenser resting on the panel in the — exact position in which you wish to mount it. A little white flour is sprinkled on the panel around the instrument, and the instrument is then remoyed. This leaves circles of flour around the bushings. The centre of cach vitcle is marked with a centre punch, and drilled. It will be found that holes so drill-| ed line up perfectly. : MEI guests’ rooms in the Robert Mouzris Hotel, Philadelphia, are fitted | with headphones, which, by a system of switches, enables the occrpants to) select from three differcnt ptogramimes, ‘as there are three receiying sets operated in a central room. \ THO is the worid’s chzmpion breadcast listener? That is to sir, what broadcast listener has tuned in the largest number of broadcast stations? William McDouald, of Chula Vista, California, U.S.A., has a record of hearing 605 different broadcast stations. His performance appears to be the best authenticated. Approximately one out of every five farmers in the United States relies on broadcast market reports and agricultural information, according to the United States Secretary of Agriculture. Science has turned a curious eye on the effect of the northern lights on radio transmission, and first steps have been taken by the National Research. Council of Canada to determine just what is the effect. Following a mecting held in Ontario of the Associated Committee on Physics and Engineering of the Council, research work has been undertaken. It is known that conditions in the upper atmosphere have a very marked effect upon the transmission of messages by radio, A statement published to the effect that a new 50 kw. German short-wave transmitter is already in operation at Zeesen is denied by the Berlin authorities, Apparently, the station heard is the experimental transmitter at Doeberitz, which is working on 37.8 metres, and gives the call-sign AFK, The Doeberitz transmitter has an energy of about Skw.