Radio and Holidays

Sun (Auckland), Volume II, Issue 541, 19 December 1928, Page 16

Radio and Holidays

! To those who contemplate purchasing | a set I can only repeat the advice given ! last week as to what sort of set to buy. . It depends largely on the amount it is desired to spend, and whether head- * phones or loud-speaker strength is required. If one is to be content to listen only to the local station, and lives in fairly close proximity to it, then a crystal set costing only a few shillings will pro- ‘ vide a host of amusement. If it ,is desired to listen further afield then a ! valve set should be bought, and the ; variety or number of valves must depend on what can be expended, i Auckland's radio dealers bear a very ■ high reputation, and if any reader is ' in doubt as to what to buy he can rest i assured that any advice given to him Iby Sun advertisers can be depended j upon.

WIRELESS BEACONS STEERING SHIPS BY RADIO Perhaps the most interesting side- | line in modem wireless development is ; the so-called direction finder, or wire- ! less compass, as used for determining the bearings or location of an or ship relatively to a given trr.nsmiti ting station. Direction finding is generally carried j out by utilising the directional property | of a frame aerial at the receiving end. When the strength of the incoming ! signal rises to a maximum, the observer knows that the plane of the frame aerial is pointing directly toward the transmitter. Alternatively, at the point of zero or minimum pick- j up, the plane of the receiving aerial is perpendicular to that line. In either case the navigator knows , his bearings on one particular transmitter, and by taking a similar crossbearing on a second known transmitting station, he is able to calculate his exact position in space either at sea or in the air.

The Department of Scientific Re- ; search has recently published an offi- ' cial report on the performance of a j different type of direction-finder, , which has been specially designed to i assist navigators in foggy weather and ; is known as the rotating beacon or wireless ‘lighthouse.” I In this case the directional properties of the wireless signal are imparted at the transmitting end, and reception takes place on an ordinary open aerial, ! The signal energy is, in fact, concenJ trated into a rotating beam, which sweeps around the horizon in the same ' way as the rays of light from a light- ; house. The official tests by the Radio Board • were carried out on. a rotating beacon installed at Fort Monckton near Gosi port. The loop aerial used for trans- ; mitting consists of six turns of wire five feet square, the system being energised with a high-frequency current of forty amperes. The aerial is pivotally mounted and is driven by specially synchronised gearing, so as to rotate at a speed of exactly one revolution a mini ute. ! At the precise instant when the con- . centrated beam from the transmitting j aerial points north, a characteristic signal is superposed on the radiated carrier wave, this signal being rej pea ted each time the rotating frame passes the same point. In order to discover his bearings relatively to the wireless beacon, it is • only necessary for an observer at sea i to record the time interval between ; two occurrences. First he must note j the exact time of receipt of the X j signal. Then he must listen in his headphones to the rise and fall in signal strength of the continual heterodyne note representing the “sweep” of the wireless beam across the ship. When this note sinks to minimum strength, he knows that the plane of the transmiti ting aerial is exactly perpendicular to the imaginary line connecting the ship to the beacon station. He now knows the direction of two lines in space. First a line porting north- • " ards, secondly a line joining his ship to the transmitting beacon. Finallv, the | time interval between these two ‘lines, , as recorded on a chronometer, mea- ! ? Ure *!L the actual angle between them, ! because, as previously explained, the I beam sweeps out a complete circle once in every sixty seconds. I t^ie result of an extended series of observations taken in this manner J the Research Committee reports that , the Fort Monckton radio “lighthouse” : has a reliable working range of over fifty miles by day and night, at which i the majority of the recorded • bearings were found to be correct to ; within, a marginal error of only two j degrees. AIRPLANE RADIO If airplane service tests undertaken by the American Telephone and Telei graph Company, between the ground j and a. cabin airplane, develop as rapidly as some of the recent experiments • \ radio communication, it will soon be Possible for anyone within reach of a telephone to communicate with anvone who may be travelling by airplane. “It may be a matter of five years,” one of the engineers of the above company stated, “and it may quite possibly be a much shorter time, before we achieve our object of an actual connection service between an object moving through the air and a station on the ground.!' In the present experiments, apparatus is being used by means of which the wave-length mav be changed intantlv. so that the most efficient and ’east-congested channels may be found from moment to moment. ANSWER TO CORRESPONDENT O.U.R. —Xo, the “Bee battery" you speak of has nothing to do with the buzzer, and it does not make honey- | comb coils.

Special Feature Broadcasts Racing and Festive Programmes RADIO will add considerably to the enjoyment of the holidays . With the excellent special programmes arranged by the broadcasting company it seems certain that not only will there be a Christmas rush to purchase sets as presents, but that those who are fortunate enough to own a radio will devote a very large portion of their leisure time to enjoying the manv good things to be broadcast during the festive

On Christmas Eve IYA will commence its session at 3 p.m. and an excellent evening programme will conclude at midnight with Christmas carols. On Christmas Day there will be broadcast a special children's session at 9 a.m., and at 11 a.m. a relay of the special Christmas service from St. Mary's Cathedral, During the rest of the holidays racing results will keep those, who cannot be present, in touch with the racing and trotting carnivals. These broadcasts will start at 11 a.m. each day, and with excellent programmes arranged for the rest of the day. IYA j will be giving practically a 12-hour j service. ■ Holiday programmes have been arranged to suit all tastes and are so varied that all classes of listener should 'be thoroughly satisfied with them.

HOME-MADE CABINETS DETAILS FOR SET-BUILDERS Many home constructors will cheerfully undertake the building of a fairly complicated receiving set, but when the question of making a cabinet arises they think twice and finally buy one or get one made by a cabinet-maker. A simple cabinet is really very easy to make. The best woods are whitewood, mahogany and oak. The first two are soft, well-grained, and easy to work. Oak is rather harder and is apt to be a little more awkward (lin wood should be used). Suppose now that we wish to make a cabinet for a set having a base- . board 14in by Sin and a panel 14in by I Tin. Take a piece of paper and stand the set on it; mark round the baseboard with a pencil: this will give the exact size of the base of the cabinet.

This should be pricked through on to a suitable piece of wood, and the base should be cut off. The set should be stood on this base and the rest of the cabinet can be built up. The back will be 14in by Tiin —that is the same size as the panel, only’ £in higher to allow for the thickness of the base. The sides should be Bfin by Tiin. The width of the baseboard is Sin, but we must allow the sides to project *in in front because of the thickness of the panel—usually iin—and £in at the back because the thickness of the back’ of the cabinet is »in.

The grain of the wood should run round the box in all cases. It only remains to fit a lid and to finish the work. The lid is lain by Slin, exactly the same width as the sides but loin long to allow for the sides.

It may be thought that such a cabinet nailed together with what are known as coffin-nails would appear very crude. But it is now possible To buy tin mouldings or headings in a variety of different woods and patterns, and it is an easy matter to run such a beading all round the base to hide the nails used to secure back and sides to the base, while a strip of beading round the lid will give a much better appearance than chamfering off the edge, which still leaves the end-grain exposed. Xo mention has been made

of cutting away part of the back to allow the terminal strips to project, because the size and position of these strips varies, but doubtless the constructor will arrange this for himself. The cabinet may be finished in a variety of ways. American whitewood may be stained and then wax-polished or varnished, or a pleasing effect may be produced by painting the cabinet with poster-paints and finishing with a good quality transparent varnish. The box may be lacquered. Mahogany and oak are woods beautiful in themselves. The former may be stained to darken it and then french-polished according to instructions recently given in this paper. Oak may be fumed or stained and then wax-polished, but on no account should it be varnished. MAKESHIFT DRILL It sometimes occurs that a small hole is required in an ebonite panel, and no drill is available. An ordinary bradawl will make a very’ good substitute, and it is surprising how quickly’ it bores a hole. The method of using it is to rotate the tool backwards and forwards through about half a turn, pressure being applied to the handy. It is advisable to occasionally lift the point out of the hole and place it back in a different position, so as to ensure that a really circular hole is made.

WORD TO THE WISE TF you are taking your radio set away for the holidays from the address given on your licence, be sure to notify the P. and T. Department, and have your licence endorsed. Failure to do this may lead to expensive and annoying Police Court proceedings.

BATTERY ISOLATION AVOIDING LEAKAGE There are many users of wireless sets who religiously isolate their l.t. , and h.t. batteries by disconnecting the leads to the set, either at the receiver or battery end, each time the set is to be switched off. They prefer this to an ordinary push-pull switch on the : front of the panel, stating that they have experienced, trouble in the earS Her days as the result of leakage in- , side the set. j It is not deemed advisable to discuss the pros and cons of the procedure here, but rather to show how this i ' isolation” idea can be put into operation in an efficient manner, and gives, in addition, the advantage that all connections, h.t., l.t. and g.b. (if the last-named is used outside the set) are broken at the same time with extreme rapidity. Instead of mounting terminals on the strip of ebonite generally provided for that purpose at the back of the cabinet fix into the hole positions smjll panel-mounting sockets and make the receiver connections for the batteries to the soldering tags at the back of the sockets. The number of sockets : required will depend, naturally, upon the number of battery points brought ■ out. As far as the battery leads them- ! selves are concerned, they must be taken to an ebonite strip half an inch i wide and a quarter of an inch thick, and whose length is governed by the number of terminals it replaces. On this piece of ebonite must be mounted a number of plugs, the holes i being drilled so that they coincide I exactly with the socket positions. Connected* to the nuts and screws at the back of these plugs we have the various battery leads, either arranged in the form of separate leads or as a multi-way batterj’ cord, whichever fancy dictates. The strip holding the leads and plugs can be withdrawn bodily from the sockets when the set is finished with, and the set is then completely isolated, and by using good duality ! ebonite for the strip there is no like- ; lihood of any leakage taking Place between the respective plugs. The idea works admirably in practice. ! IYA CHILDREN’S COMMITTEE CHRISTMAS DAY SESSION A meeting of the IYA Childrens Committee was held during last week, when there were present: The Rev. Lionel B. Fletcher, presiding, Xncle Leo ” at ITA: Rev. L. B. Busfield, Sundav School Union; Mr. T. T. Garland “Uncle Tom” at ITA; Mr. E. Pud=on Headmasters’ Association; Miss Jean Begg, T.W.C.A.; Miss Flatt, X.Z. League of Pen women; Miss R. Palmer, children’s organiser at 11A. and Mr. S. J. Hayden, station director at IYA. . An apology for absence was received from Mrs. Bruce McKenzie, who forwarded a letter in connection with a request for support for the installation of a wireless set at the "Waikeria prison camp. The committee felt that the request was somewhat outside its province, and decided to take

no action. ; The Radio Broadcasting Company I wrote intimating that it had been de- ■ cided to hold the children’s session for | Christmas Day in the morning at 9 a.m., in accordance with the com- • mittee’s previous resolution, and furj ther intimated that it had decided to ; adopt the committee’s resolution re- ! garding the introduction of a gramophone record on occasional children’s ; programmes, the record to be accom- | paniea by a short comment, j The chairman intimated in conneej tion with unsolicited donations which : had come to hand, that in furtherance lof the committee's scheme to install ! crystal sets in cases where deserving i circumstances warranted, a satisfaci tory quotation had been received from j a local radio firm, and it was decided i to proceed with the matter immedi- , ately. ; The committee passed a resolution j recommending the company to intro- | duce a series of talks on “Vocational i Guidance,” to be given by prominent ! people during the children’s session, i once a fortnight. IYA MUSICAL AND DRAMATIC COMMITTEE The IYA Musical and Dramatic : Committee met at the studio, where • there were .present: Messrs. .Karl At- ; kinson, in the chair, Auckland Gramoj phone Society; C. B. Plummer, Auckland Choral Society; L. E. Lambert, ■ Bohemian Orchestra; V. Trask, Athenian Club; Mrs. Carr-Tibbitts. New j Zealand League of Penwomen. Mr. G. ;T. Lee, Aeolian Orchestra, Mr. J. F. ' Montague, Auckland Comedy Players; i Miss Delaney, Ainsley Operatic Soi ciety: Mr. S. J. Hayden, station direc- ' tor at IYA; Mr. D. Wrathall, pro- | gramme organiser at IYA. ; The committee discussed at length i the proposed one-act play competition i for which some entries had already : been received. i It was felt that a short talk should I be put over the air by Mr. F. McCalj lum, explaining the details in connec- ■ tion with the play, and it was decided ;to .recommend the company accordingly. The University students’ delegate advised that arrangements had been completed with the station for the broadcast of a debate, in accordance with the committee’s previous resolution, to take place on January’ 9. 1929. The Radio Broadcasting Company’ : submitted an outline of a play which had been broadcast in America with success, and the committee decided to recommend that the play be broadcast, as it was felt that the particular performance would be of exceptional in- ; terest to listeners. A suggestion was made that a Maori night be held. This was apj g r °y? d , b i‘ the committee, and it was I decided to recommend the companv , accordingly. * • STOPPING NOISES As a rule, it is usual to employ a a variable condenser on the short waves for controlling reaction. It is impossible to keep such a condenser completely free from dust, and any small particles which become lodged between the two sets of plates will cause a crackle and scraping noise as the condenser spindle is turned. This trouble may be removed by inserting a fixed condenser in series with the variable one. The value of this fixed condenser may be in the neighbourhood of .001, although a much smaller one can be employed if * the variable reaction condenser is found to be too large. Incidentally, such a ! condenser acts as a safeguard for the | valves in the event of the variable conI denser becoming shorted, in which I case iti s possible for valves to be burnt | out. As a matter of fact, it is desir- ■ able to insert a series condenser for the above reason even on sets ini tended for reception on the higher I waves.