Radio Review

Evening Star, Issue 19712, 12 November 1927, Page 17

Radio Review

-[By “HENRY.”]—

Flashes from Everywhere.

TERMS AND EXPRESSIONS. SIM RLE EXPLANATIONS. The following list is taken from Hannswortb’s ‘"Wireless Encyclopaedia,’ nnd has been condensed and selected for this column by “Henry”:— Trembler.—An interrupter for induction coils resembling the hammer break, but on a yuall scale. The instrument is mounted on an ebonite panel, and is usually attached to the end of the coil cover.

to broadcast when asked. Two or three Sundays ago the band was playing in one of tho city theatres, and on good authority I am told permission was asked to broadcast that concert. The band, however, did not go on the air that night, tho excuse being that the attendances would bo affected. I fail to sco that argument, as on the night in question nothing would have been said about broadcasting the band until the band was ready to play. . Anyone who really wanted to bear tho band would, by that time, have been seated in tho theatre. It would have been foolish for anyone on that night to stay at home on the off chance that the baud concert would go through 4YA. A previous concert advertisement plainly stated that the performance would nut be broadcast. However, the above letter seems _to make it quite clear that the Regimental Band does not mind being broadcast sometimes. EMPIRE BROADCASTS. The remarkable success attained by tho Australian shortwave station, 2ME, working in _ conjunction with 2FC. in transmitting a programme which could be picked up and successfully rebroadcast in England, is worthy of more than passing notice, and adds another to the many pioneering achievements of Australian broadcasting interests (writes “Thermion,” in .the Auckland ‘Herald’). Listeners of a few years’ standing who have been able to follow Australian broadcasting developments have always admired tho energy, enthusiasm, and ability with which new problems havo been attacked, with little, if any, consideration for tho financial expenditure nece.sarily involved in the experiments. Australia occupies a high position in tho broadcasting world, as must bo considered inevitable when it erects a station capable of Empire broadcasting some months before the British Broadcasting Corporation, which lias huge financial resources, as well as the assistance of tho best organised broadcasting service the world has seen. The Sydney station, 2ME, which transmits on 28 and 28.5 metres on a power understood to be 6,000 watts, was erected by Amalgamated Wireless, Limited, and can bo used for transmitting 2FC’s programmes simultaneously with the usual broadcast on 442 metres. Tho transmissions from 2ME were heard very clearly in Auckland last Friday evening (October 28), on tho occasion of a special broadcast to America, and again on Tuesday afternoon (November 1), when tho description of the Melbourne Cup race was received. EXPERIMENT WITH W r AVES. ‘ Science Service ’ stales that radio engineers in tho United States are much interested in a scries of investigations carried out by Herbert J. Reich, of tho Department of Physics at Cornell University. These experiments wore made to determine whether the apparent direction of a radio wave changes ns it travels through space. By means of a loop antenna, such as is used in radio compass stations to locate the position of ships at sen, a series of tests was made on three broadcasting stations beard at Ithaca. These were WGY, Schenectady, and WEAF and WNYC, New York. When the loop antenna is at right angles to tho apparent direction of the station it cannot bo heard. Tho changes in apparent direction, however, have been found to bo very marked and rapid, sometimes changing as much as ISOdcg in 15 minutes. When the average for two-ininuto periods was taken changes as great as dOdog were recorded in tho same time.

Trigger flattery.—Name given to a small battery winch is inserted in the grid circuit to give the grid its initial charge when the valve is used for transmission. Triodc.—This is another name for the three-electrode valve. Triple Condenser. —A triple condenser is a condenser having three identical goto of fixed and moving vanes, the latter being all on the one spindle. T.S.E.—These are the initials of the i French term “ telegraphic sans fil,” or telegraphy without wires. T.S.H.—These, letters form the letters of the words 11 telegralia sin liilos ” the Spanish term for wireless. telegraphy. Tube.—This is an American term used largely for valves of all kinds. Tuned Anode. —Tuned anode is an expression applied to a method of amplification characterised by the.use of an induction coil in the anode circuit of th© valve. Tuner. —The expression tuner is applied in radio to an apparatus comprising an inductance, capacity, or both, and adapted for regulating a receiving or transmitting set so that messages can be sent out or received at any tiesired wave length. Tuning Switch.—The term “ tuning switch ” is applied to all forms of selector switch, facilitating tuning operations in a wireless receiving or transmitting set. Twin-wire Aerial.—Typo of aerial tinploying two wires running parallel to and insulated from each other except at the point of contact with the lead-in wire. Two-electrode Valve.—The two-elec-trode valve has only two electrodes—the filament and the anode. The twoclcctrode valve was invented by J. A. .Filming, and was the first step forward in wireless telegraphy. Umbrella Aerial.—An aerial whose component wires radiate from a centre .pole or mast like the ribs of an umbrella. Valve.—Form of rectifier or amplifier first introduced by J. A. Fleming, ft generally contains three main parts—the filament, grid, and plate. Variable Condenser.—The term ‘■variable condenser” is generally applied to instruments of the moving vane type. ’ Variable Grid Leak.—Term used to describe all forms of grid leak, with ready forms for altering their valve. Variable Inductance. —Term used to describe all forms of inductance, which are so arranged that the effective valve ran bo altered at will. Variable Resistance. —Strictly speaking, all forms of adjustable resistance. ' Vario-cou pier.—Name given to a typo of tuning device. Variometer .~A form of variable inductance in which the variations are made without alteration to the amount of conductor. Vernier Condenser. —A condenser of low value, used in a circuit for fine tuning purposes. Volt.—The unit of electro motive force. Watt Hint of electrical power. Wave Length.—The distance between corresponding phases of consecutive waves in a wave train measured in the direction of propagation at any instant. Wave Trap.—A device incorporated in a radio receiving installation for eliminating local interference. Whistling.—Sound heard in the speaker of a receiving set. ft is generally due to the reaction coil being too tightly coupled. Vagi Spark Gap.—-Form of spark gap duo to H. Yagi. (Conclusion A RANDS AND BROADCASTING. The secretary of the Band of Ist Battalion, Otago Regiment, writes;— “ In Saturday’s issue of tbo ‘ Evening Star ’ you have a paragraph in your columns to which I take the greatest txccption. It runs as follows: —‘With reference to a statement in last week’s notes to the effect that bandmasters do not favor broadcasting in Dunedin, there is at least one conductor who has given broadcasting every encouragement. ■ He . is tho conductor of the St. Hilda Rand,’ etc. “I should like to point out tliat iuy band—tho Band of tho Ist Battalion, Otago Regiment—has broadcast many concerts this past winter at great financial loss, as well as at great inconvenience to tho bandsmen on occasions. “ According to the management of 4YA, it has received many letters and messages of congratulation on the concerts provided, and I myself have received one or two donations towards the band’s funds from wireless enthusiasts as a token of appreciation. “Whenever the band of tho Ist Battalion, Otago Regiment, has been approached by the Broadcasting Company the bandsmen have been only too willing to turn out to give a studio concert, even though the small room was not large enough to accommodate the whole band. Tims players bad to stand all evening, and some Were compelled to stand down and not play. “Of all our concerts given during the winter T believe there have been only two which have not been broadcast, and then, as stated previously, the band lias paraded to give studio concerts during the week. I think I am right, also in saying that we have been mentioned in your notes once. , Having tho band books in my posses- ’ sion, f am willing to show you at any time the collections taken when broadcasting as against the t collections taken when not broadcasting, and then, maybe, you will understand and be astounded at the difference. Then, on top of all the foregoing, you have to hear in mind that the Band of the Ist Battalion. Otago Regiment, is a military band, for which everything has to be specially imported—music, instruments, as well as the scarlet uniforms. Where a brass band pays 20s for some musical selection, a military hand has to pay at least 27s 6d for the same j .selection. When all this is borne in mind you will understand why, as you say, '‘bandmasters are averse to broadcasting.' Yet the Regimental Band? is always .willing to broadcast when asked.” The paragraph which has caused the trouble contained two little words which seem- to have been overlooked, or to which no importance has been attached. They wore “at least.” It:was.stated last week that “ at least one conductor has given broadcasting every encouragement.” The paragraph did not sav that the conductor mentioned was tho ’ only one who was not averse to broadcasting. “Henry” would like" the Regimental Band secretary to bear that 'in. mind. The letter states that , the Regimental Band is always willing

That these direction changes arc not duo to atmospheric changes was shown when'tests were made simultaneously with the transmission of WEAF and WNYC, both of New York City, and nearly the same wave length. Sometimes tho sotting of tho loop for these stations differed as much as3odeg. On one evening in August it was found impossible to dotermiuo tbo direction of any station, as the signals camo as loud despite the direction of the loon, lb was at first supposed, says Mr Rcicli, that something was wrong with tho receiver. but .this was shown not to be tho case. However, there was_ at the time a brilliant display of tho Northern Lights. One theory that had been suggested to account for tiic direction changes was that when the radio waves cross tho boundary between darkness and daylight they arc bent, like light passing from water to air. But, while marked deflections wore found just after sunset and before sunrise, they were not always in tho right direction. When Fading occurred and a lorn! signal became faint there were usually_ rapid direction changes; but these did not always follow each other, so the cause of the changes is still in doubt. SUMMER RADIO. Summer time is hero once more, and at this period there are a number of little jobs that should be carried out by radio enthusiasts. Tu the first place, all masts should receive attention. They hav6 withstood tho rain and gales of winter, and will require examination, and probably some repair. Perhaps new guys will bo found necessary. I may advise the use of so!id_ galvanised wire for new guys, as this typo of wire withslands tbo weather hotter than stranded cable. Metal masts should bo sealed and brightened under a now coat' of- paint, for, if nob looked after,, they will soon corrode. A _ quick-drying paint with an enamel finish is about the best rustproof covering to use. With wooden masts slits must bo looked for. If noticed in time they should be well filled and painted to prevent water lodging in them, thus rotting tho wood. The lead to tbo earth plate outside should bo carefully examined, and, if worn, replaced by a new one. Those who indulge in outdoor sports on summer nights will do well not to neglect their accumulators. It will save money in the end. In cases where tho set will not ho used at all the accumulator should be fully charged, after which the acid should bo emptied out. Leave the accumulator upside down to drain and dry. "When again required for use fill with acid to the correct specific gravity and charge in the usual manner. Perhaps you will only want to use tlio set now and again—say, only on wet evenings, If so," take caro that tho accumulator is charged every three weeks, whether the set is used or not. ’ To prevent unduo evaporation of tho liquid accumulators should be placed in cool spots during the very hot days. The above points also apply to h.t. accumulators, although the period before they arc charged is lengthened. I may add, however, that frequent charges for the h.t. are preferable to long charges every three months or so. High tension batteries of the dry typo should not be exposed to the sun, but generally they give better service iii tho hot weather, for the air is dryer and the damp atmosphere very soon affects the dry battery.

“Henry" wiU be pleased to answer any questions through this column relating to the fascinating bb J; h eormJLde&t mat sign' his pamo and address (not necessarily for publication). Newsy items will be welcomed.

As the hours of daylight increase the range tails oil, and I may here remind newcomers not to expect too much from distant stations. The complaint will disappear towards winter. . Finally, reverting hack to aerials, don’t forget to clean the insulators, for even in tho cleanest of atmospheres grime and dirt will collect and mar reception by reducing the aerial insulation. SELECTING THE TRANSFORMER. Apart from their actual powers of amplification, audio transformers offer a fairly easy method of connecting up tho two valves, it is dealing with, or, in other words, of handing tho signals from the plate of one valve to the grid of the next, for this cannot be done, for obvious reasons, by a straight connection. More than two audio transformers arc never used (unless of a special type, called “push-pull” transformers), for the amount of distortion from each, though it may bo small, would be so accentuated by the time tho third stage was reached that_ it would be decidedly more than noticeable. So, no matter how good a pair of transformers may be, the temptation to add more should never bo gratified, for distortion will inevitably result. Many technical rules and points govern the selection of a transformer, but, as most of them are hidden from the common gaze, they are of little value in the choice of a reliable make. The best criterion of the likelihood of its value is its weight—in other words, the quantity of iron contained in its core. The transformers with the heaviest cores, as a rule, will be found the best. There are one or two , alternative methods of audio-frequency amplification, as resistance-coupling and impedance, both of which, in their freedom from distortion (resistance coupling can be made absolutely pure) are superior to transformers, but they have several disadvantages which, from tho popular viewpoint, scarcely appear to be off-set bq their better qualities, Still popular opinion is not always right, and tho time may come when this method will receive the support which it undoubtedly deserves. It is at least worthy of further mention. BROTHER BILL’S RECIPES. Big Brother Bill, of 4YA. has received a reply to “Frantic Father’s” verse (published last week). It arrived at tho station signed by “Indignant Mother,” who writes: — Dear Brother Bill, Big Brother Bill, I’m dreadfully upset, And hasten to convey to you My very deep regret For tho way my husband wrote to you About your recipes. Ho ought to crave forgiveness Upon his bended knees. You did not know who wrote you, But tho children found it out, And they gave him such a doing, He wiis almost “counted out”; Although with grief I say it, Dad’s been an awful fibber; But when ho wroto that screed to you Ho was suffering from his liver. And when ho docs get livery, And wo havo him to appease, Nothing makes him smile hko sweets Made from your recipes. Our children are most obedient, And do always what we say, And when they make some toffee Dad’s first to shout “ hurray.” They scour out every pot and pan As soon as they are finished, And tho comfort of our homo is not In tho least diminished. Although the bills have mounted up, Tho reason’s easily found; We’ve got to make such heaps of sweets For dad, when he’s around. Tlio children don’t cat sweets in bed, Or make their clothes a moss; Tboy’ro always clean and tidy, And most careful of their dress. There’s never toffee on the chairs, Or fudge upon the mat, Or anything to spoil dad’s pants, Or stick upon tho cat. Our house is just as spick and span, As when we first were married; And the parrot never chokes himself, For wc haven’t got a parrot. Now, though poor dad’s a good old sort, And tho children all adore him, On occasions when he’s livery The best thing’s to ignore him. So don’t take any notice Of his protest, _ if you please, But keep on sending through the air Your scrumptious recipes. Another poem, this time from little “Sister Mercia.” lias also oomo to hand. Sho joins with “Indignant Mother” in condemning “Frantic Father.” HERE AND THERE. 3YA Christchurch has been the most prominent New Zealand station this week. Tho race descriptions were, as usual, we],l handled by Mr Allardycc, anl tho concert sessions were well up to standard. All the transmissions from 3YA -were well modulated, and the volume was good. ... Oswalds seem to havo faded into the background in •Dunedin' just now', for, with tho exception of one or two prowling round 3YA, they havo been almost unnoticcablo during tbo past week. Now that the daylight saving is in force listeners will have realised that the Brisbane, Sydney, and Melbourne stations do not come in until 10.30 at night, and that Adelaide, commencing his 8 o’clock programme, is not picked up until 11 o’clock here. Listeners are not so keen now to listen to the Aussies, although I know some who sit up and patiently wait for the stations across the Tasman. I havo not heard of anyone in Dunedin yet hearing SSW, Research Department, Marconi Works, Chelmsford, England. This station was on tho air early this week, and northern reports have it that the strength at which it was heard was astounding. PCJJ, Holland, is moving to a more suitable site, and various alterations are being made to tho apparatus. Fading with 2YA has not been so frequent or so severe lately. Taken all round. 4YA’s programmes have been very good during tlio last week Perhaps if the artists were paid we might hear something even better. Performers would be sure to sing or play better if they knew they wmuld leave the station a little richer than when they cutered. ■ I have not bad very much time to devote to listening this iveek, and did not even tune in IYA. I am told, however, that his concerts are quite up to the usual and are coming in at good strength. One of the latest novelties is a complete set in' an ordinary pipe. The detector and terminals > are clipped to the stem and the coil is placed in the bowl. A wire attached to a tree serves as an aerial.

Uncle George’s (2BL) “ Good night” has been heard in many places, and the latest is in the coast of South

America. The captain of a sailing vessel, recently in the Sydney harbor, called'in at the 2BL studio to inlonn Undo George of this. The sailing vessol in question anchored in quarantine after a very stormy passage, and tuning to 2BL heard an account read of the hardships all on hoard had encountered in the passage across the Pacilic. Wrestling is very popular in Sydney, and realising this 2BL has made arrangements for descriptions of all the principal bouts to be broadcast from the Stadium, . A dial that wobbles as it rotates docs not affect the working qualities of a radio receiver, but it certainly does spoil its appearance. When buying dials, have the dealer spin them on the shaft of a condenser and make sure that they run true before purchasing. Jt is often possible to true-up a'dial on a shaft by fitting a hit of paper or shim brass in the shaft hole, or by polishing tho shaft on ono sido or the other with emery paper. The Secretary of the General Post Office, Wellington, advises that under no eireumsfauces is tho telephone or earth wire attached to a telephone instrument permitted to be used as an earth connection for a radio receiving sot. A huge radio exhibition is to bo held in tho Sydney Town Hall in March, 1928., It is interesting to_ note the progress of the radio exhibitions which have been held during tho last three years. In the first year tho main hall was used, in the second the basement, and next year both the main hall and the basement will bo required. Often it is desirable to operate the loud-speaker in another room from that in which the radio receiver is installed. The simplest way to do this is to buy a sufficient length of ordinary electric light drop cord, an open circuit jack, and an extra plug. Solder the jack to tho two wires at ono end of the drop cord and lit the plug to the other end. Wednesday night's relay irom the Strand Theatre, Christchurch, by 3YA was cut short owing to_ the electric power from Coleridge going off. The station, however, filled _ up tho programme very nicely with community singing. CORRESPONDENCE. “C Battery” writes: —“l Lave a two-valve Brownie amplifier, using P.M. 5-Milliard valves. There are terminals for grid bias battery connections, but in connecting in a 0 battery—trying all voltages from 1-s upwards—volume fades right away, and I find it best to do without a C battery. Am I using more B battery in not using a C battery, or do the P.M. o’s not require grid bias? Also, if I used a power valve in the last stage would a C battery be necessary?”— Possibly you have had the _C_ battery round the wrong way. If this is so, by adding more voltage to the C battery you are making it more positive, consequently losing signal strength. You may also not have enough B battery voltage. The P.M. 5 valve requires 4J volts C bias at 90 volts. _ Tt is essential to use a C battery with a power tube. “Crystal” writes:—“l have a single coil crystal set which has suddenly ceased to function. Can you explain the cause of this?”—Look over your aerial and earth leads. Either one may be defective. Also make sure there are no broken connections in the set, or that tho coil is not broken. Try another crystal, and test the' ‘phones for any deficiency. “E.C.W.” writes:—“How may degrees is KFON bleow 3YA?”—This is a hard question to answer, as you do not state the make of your set. therefore I do not know the settings of your dials. I should sav KFON is about 12 degrees below Christchurch.