NOTES AND COMMENTS

Radio Record, Volume I, Issue 35, 16 March 1928, Page 6

NOTES AND COMMENTS

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Accumulators of the lead plate type | maintain their voltdge very well until almost completely discharged. Although this is a desirable characteristic, it makes the voltmeter a poor indicator. A hydrometer is the most satisfactory device, and has the added advantage of being inexpensive." If a voltmeter is used, the battery should be tested under "Joad." Usually the receiver draws very little current, so merely turning on the filaments helps only slighily.. There are voltmeters on the market which have a low resistance of high current carrying capacity, which is connected across the battery when it is tested. These are quite satisfactory. ; An American writer asks: ‘How can any human being ever be blase about the wonders of broadcasting when he realises that the isolated lumberjack, sitting down to his crude meal of canned billy and hard bread, may mellow his supper with the greatest music the world has ever offered? How can any one accept as a matter-of-fact the radio programmes sent out to-day, when he knows that men, women and children to whom finer music was an unknown thing now have the best of it in their daily lives?"

If the set is to be taken away for tse on a motor tour and is to be opetated anywhere near the car, it is & simple matter to use the car __ battery for an A battery, thus avoiding the necessity of carrying an accumulator or dry cells specially for the purpose. If the car batterv is of the 12-volt type it will be mecessary to take off only 6 or 4 volts, according to the tvpe of valves used. In that case portion of the battery may also be used as a C battery. The new shielded grid valve has a high amplification constant, which makes it possible to attain a radio frequency voltage amplification per stage of from 30 to 50 depending on the circuit constants with which the tube is operated. This gain is much more than would be lost in a reasonably well designed and coupled chain of tuned circuits. Tn cases where interference is caused bv the electric motors used in vacuum cleaners or vibrators, the trouble may often be reduced hy shunting two 1 mfd. bypass condensers connected in series, across the 110 volt line, at the outlet where the electrical appliance is connected. The mid point of the two condersers is connected to ground, preferably throuch a 6 ampere fuse, So that in case one of the condensers hecame defective, the fuse would operate and prevent a fire. Of course, anv motor which produces had radio interference is usually in need of attention, such as cleaning the hrushes and comnutator, which can he done by any reliable electric service shop. In Australia there are manv listeners, perhaps a majoritv, who rely on_ the erystal sets for their services. Some particulars supplied by the Commonwealth Postmaster-General’s Department to the: Royal Commission _ last year showed that in the metronolitan areas, excepting Hobart, the crvstal listeners amounted to over 60 per cent of the total number of listeners When listening-in away from home the teinporarv aerial need not be longer than 50 feet, and should be as high as circumstances will nermit. It is a good plan to use insulated wire if there is any fear of poor insulation with hare wire. The temporarv earth mav_ cotsist of a wire making good electrical connection with a spade, pick, or iron rod driven a short distance in moist earth. An ordinary 2 ampere tungar battery charger mav be used as an A_ hbatterv eliminator by connecting five 14 voit dry cells in series across the output of the charger, with the positive of the 73 volt group of drv cells connected to the positive charging lead, and the negative of the drv cell group to the negative charging lead. ‘The: drv cells act as a filter condenser of high capacity, and will last practically their shelf life. since little current is drawn from them while the set 1s in operation. It is important, however, to turn off the receiving set filament switch as well as the 110 volt power input to the charger, when finished with reception, for otherwise the dry batteries will quickly be run down. A loudspeaker output unit or an output filter is a device which provides an auxiliary path for the direct current to the power valve which prevents it flowing in the windings of the speaker, It is so. designed that the alternating of speech current goes through the speaker, where it is wanfed. An output transformer performs the same function, ‘The object is to prevent burning out the speaker winding, and, what’is more important, to eliminate this constant strain which impairs the quality and possible output of some types of speakers. . . KDKA at Pittsburg, U.S.A., broadcasts simultaneously: on 3.15.8, 62.5 and 27 imetres nightly, except Sundays, between 8 and 10 p.m. Occasionally the 42.95 metres wavelength is used. Transmission on 2.5 metres has been abantloned for the present, |

= . Novices often express curiosity re garding the reason for vaives having a silvery appearance. ‘This silvery coat you see is nothing more than the deposit of magnesium, which accumulates on the inner surface during the process of getting rid of gasses inside the glass bulb. That is, after the valve has been evacuated as tnuch as possible with mercury pumps, a small piece of magnesium of which is attached to the plate of the valve is heated with a radio frequency coil, until it vaporises and then flashes. When this happens, the metal is deposited on the inside of the glass walls, at the same time combining with any of the gases present ond completely eliminating them. The degree of s11very deposit ig not a factor In the summer, if a meta) plate, or a petro] tin filled with coke, buried in the ground, is used for an "earth," reception sometimes becomes difficult, on account of the increased resistance of the dry ground in contact with and surrounding the plate. A great improvement can often he effected by thoroughly soaking the ground wilh water now and then. The Firestone Tire and Rubber Company, of Akron, Olno, U.S.A., has been granted an experimental three-month license to enable it to use a transmitter with call letters 8XAS to communicate with the men in charge at their rubber plantations in Liberia The license permits the use of from 200 to 5000 watts of power on waves from 5.35 metres to 166 metres and from 42.8 to 52.6 metres. Stenographers desiring to increase their speed in shorthand find that taking down radio sermons or talks is a good way to do it.

. Sir Thomas Beecham, well-known English musician, conducted the New York Philharmonic Orchestra recently on the stage of Carnegie Hall, New York City, This marked the firs appearance of Sir Thonias as a conductor on an American stage, although he has been in that country several times, and it also marked his first appearanc as a radio artist. When he stepped on the stage three microphones faced him, all of which were connected with the transmitter of station WOR, which broadcast the concert. Less than a year ago Sir Thomas classified radio as "‘music’s greatest menace," and he has characterised English broadcasting as.a "stupidity and a crime against music." A remarkable achievement is claimed by a Mr. L. S. J. Cranse, of Summit, /New Jersey, U.S.A., who has proof of reception of no fewer than 648 broadcast stations. He says:-‘During the two and a half years that I haye been accumulating. my log, I have made a rule not to enter a station on my log unless I was able to hear enough of the programme to have the reception verified, and even with this strict rule in force I have had the good fortune to list 543 stations-all verified, of course." A loudspeaker should be tried out in different rooms, with the listeners sitting at various distances. A marked improvement in tone and reduction of static interference will be noted when the distance between loudspeaker and listeners is increased. A plan to substitute five high-power-ed broadcasting statious for certain existing stations to serve Great Britain and Northern Ireland are to be placed before the British PostmasterGeneral. The scheme provides for a high-powered station near London, another in the west, a third in the north," a fourth in Scotland, and a fifth in Northern Ireland. tur

US UUUISLI SLIP et Docs a high altitude add to the carrying power of a radio station? Envineers of WWNC think it does. WWNC | is located on the highest point east of the Rocky Mountains, more than 2100 feet above sea level. The station, Which uses 1009 watts, is regularly heard in forty-five of the forty-eight States, as well as in the southern provinces of Canada, Guatemala, and Canal Zone. e A recent nation-wide vocal competition proved the remarkable carrying power of the station. ‘Lhe resulting vote from the radio audience of this station, from which the State Audition of North Carolina was broadcast, was twice as great as that of other stations at lower altitudes where State auditions were also held. ,

ao were rr eee ee | Radio programmes will soon be brought into American homes l:y means of the telephone wires. ‘This plan has been studied a long time, costliness of installation retarding its adoption. Now, however, a new deyice invented ly General Squier, U.S.A., retired, is reported as bringing the cost | down to a nominal figure, and it is being adopted for public use throughout the United States. In a significant statement issued recently, O. H. Caldwell, acting-chairman of the U.S. Radio Commission, said :-‘‘Broadcasting service in cities may start this year on the inevitable transfer to wires leaving the channels of the air to serve the cpen spaces and the rural communities," Difficulty is often experienced in making a satisfactory job of soldering the earth wire on to a water’ pipe, un-| Jess the work is carried out in a certain mauner. This is due to the reluctance of the pipe to heat up to the right teniperature necessary for proper soldering, on account of the quick cooling action of the water in it. ‘Ihe job is quickly and easily carried out simply by turning the water off at the meter, and by turning on the taps close at hand, running the water out of the pipe te be soldered. ‘The use of a blowamp, makes the job very much easier, aud ensures a well-soldered and lasting connection.

Radio statisticians who try to determine the relative popularity of broadcast features haye’a new measuring stick to work with: the kilowatt-hour. According to Arthur Williams, vice-presi-dent of the New York Edison Company, New Yorkers burned up 6000dol. (£1200) worth of extra electricity the night of the Tunney-Dempsey fight, listening to the radio description of the battle and | Staying up to-read the mewspaper accounts that appeared shortly afterward. ~The extra load carried by the company’s generators did not fall off until 3 o’clock the next morning. A simple and efficient method of rejuvenating valves which have ‘‘gone dead" is to turn their filaments up to normal brilliancy and then to reverse the polarity of the ‘‘B’’ battery, connecting its positive terminal to "A+" and its negative to the lead which is normally connected to the "BY". The valyes should be left connected in this manner for a full hour; the filament current should then be turned down to the lowest point and left this way for another half-hour. In cases where the valves are unusually poor, the treatment may have to be repeated. After the valves have been allowed to cool off, the batteries should be connected in their correct manner. It should be borne in mind that some types of valves are not suitable for rejuvenation; those, like the WD11 and UX112, which have not thoriated filaments, are not amenable to this treatment. When 201A-type valves are used as detectors, it is advisable to use a filament rheostat of about 30 ohms; because although these valves are not very critical to changes in filament voltage they are most sensitive at one particular point. A 6-ohm rheostat does not permit the fine regulation of voltage that is obtained with one of higher resistance; in some cases the point at which the valve operates most efliciently is much lower than the rated voltage. we SINE INET ot

Mr. D. Hekel, of Bandoeng, Java, writes to the New York ‘‘Radio News’’: "The short-wave phone transmitter at Malabar, Java, is now working again regularly with 25 kilowatts on 17.4 metres, with the Dutch short-wave phone station PCLL, 18.7 metres, from 120 to 1820 GMT on Mondays, Wednesdays, and Fridays. As these stations now come through very well, there will be opened within a few weeks a short-wave phone service between Holland and Java. This will be the longest in the world-more than twice the length of the trans-Atlantic system. As to heavy tropical static: this is indeed very serious, especially on the higher wavelengths, but depends also on the season. On the short waves, however, it is no obstacle. Most of the inland and foreign traflic of the Dutch East Indies is handled by the short-wave transmitters, ANC, AND, ANF, and ANH (Laboratory)." The Melbourne ‘Listener In’’ says: ‘ver since the commencement of wireless broadcasting criticism of some kind or other has been directed against every | broadcasting station the world over. Much has been well-intentioned, some ill-intentioned, and most of it positively selfish: What I mean is that the critic usually approaches things from his own individual point of view, and consequenty it behoyes those responsible for the broadcasting services not to take him over seriously, seeing that they have to please many hundreds of thousands of other listeners of varying tastes. However, the critic who is kindly and constructively disposed is always heeded by enterprising broadcasters, for from him many hints are gleaned; but unfortunately this class of critic is all too rare.’’