NEWS AND NOTES

Radio Record, Volume I, Issue 19, 25 November 1927, Page 8

NEWS AND NOTES

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Even though the lead-in wire is insulated, never let it touch, against any metal. This means the cornice around the edge of the roof, the metal window screens or weather strip, or any metal. In spite of the insulation, there will be leakage here, and weaker reception will be caused, On some crystals, only a slight contact of the cat’s whisker is needed. Galena and silicon are of this kind. Iron pyrites makes a firm heavy contact. Using carborundumi, the point of the cat’s whisker can even be jabbed under the surface of the crystal. Phonograph needles are excellent for use with a carborundum crystal. Atmospheric conditiots and location play a very important part in how well and how much you can receive. Night is Lxvter than day; winter is slightly better than summer, and there will be a great variation in strength of reception front day to day in summer time. Batteries are generally rated at their ampere hours capacity, ‘That is, a_ 60 ampere-hour battery is rated as heing able to deliver one ampere pei hour during a period of 60 hours. It is advisable, however, not to let a battery become more than three-quarters @ischarged, It will then last longer, and should give good service for years.

Vernier dials should be used on near'y all vaxiable condensers, as they permit mach finer tuning to be obtained. This makes for ease in tutiing in weak signals and improves the efficiency of the set. All joints should be soldered as this increases the electrical efficiency as Well as the mechanical, An ontside aerjal should be inspected at ieast twice a year. Ins*iators covered with soot, and dit should be thoromehly cleaned with a bresh and 2asoline. A iaver of soot or dirt in the insulators permits a lot of energy to teak off to the poles, and thence to the zround. _ According to statements from Creat Britain an attempt is being made to overcome fading by using two separate aerials for picking up the signals. The two aerials will be spaced some ‘listance ‘apart. The reason for this ‘s that when wireless signals fade the fading effect is limited to a relatively small area for each. When signals are weak at one spot thev are quite strong at another. .By suitably spacine the two aerials it should be possthle to "fect a sort of balance between thie ‘"tdes in one spot and thse in another. so that when the signals from one verial are weak those from the other will he strong, thus maintaining a comparatively aunvarvine signal strength attitable for rebroadcasting., It'is un: lerstood that exneriments with the new system will be begun almost at once The range of transmitting and receiving by radio depends somewhat upon ihe nature of the territory lying Detween the transmitting station and the receiving atrial, The greatest range for i given power is obtained over water. Any metal, particularly iron and steel, ving between the broadcast station and receiving aerial, will cause loss of signal strength. Such metal may either be in the form of an artificial structure, such as buildiny frameworks or iron roofs, or may be in the form of ore ‘leposits. Some regions, owing to metal ‘leposits in the earth are noted for poor reception. : Never run the lead-in any long. distdnce through your house. Once inside the house the lead-in should be as short as possible. If the lead-in is long inside the house, the walls and ceilings will absorb most of the radiofrequency energy that should flow into the receiving set. In other words, strength of reception will be greatly reduced. Flace your receiving set near he point where the lcad-in enters the | 10nSe, :

ana 4 All listeners should keep a list of their dial readings for the various broadcast stations. This list not only saves a deal of time ordinarily wasted in hunting for stations, but enables us to pick up desired stations in a more satisfactory manner, o egies |

frequency and audio frequency amplification is that radio frequeucy iticreases the strength of distant stations so that they sound louder, while audio frequency merely boosts up all signals in proportion. The majority of detector circtits use rezeneration, since this is really a form of radio frequency amplification occurring within the detector valve. This gives a great increase of the strength of signals, and can be compared with one stage of radio frequency .amplification. Therefore, if one desires to increase the sensitivity of his detector circuit he certainly should incorporate regeneration. | The main difference between radio When plate voltages above 45 are used on an audio frequency amplifier frrespective of the number of valves used, a "C" battery should be inserted in the circuit. Such a battery does two things.: it improves the quality of the reception and it decreases the ‘‘B" battery current, thereby lengthening the life of the battery. As a "C" battery costs less than 5s., it is well worth the expense, as it certainly inereases the *‘B" battery life by more than this. These batteries are ;-ery small, and will last for at least « ycar as mo current is taken from them. Kordia, a German, patented the first rotary variable condenser in 1893, but this type of condenser did not make its } debut in the radio field until about 1962. The first type consisted of two concentric cylinders, one of which was movable. The sliding plate condenser eamle next, and were the popular type about 1910. Then came the rotating plate condensers, which are used at the present time.

i | Applications by 51,0, Melbourne, for broadcasting licenses for South Aus- | tralia, West Australia, and ‘Tasmania ‘have been lodged- with the Commonwealth Postmaster-General’s Department. This is one of the most important wireless developments since the inception of broadcasting im Australia, and if the applications are granted 8L,0, Mclbourne, will establish a chain of stations throughout the States mentioned, each of which will provide a broadcasting service of equal efficiency ‘to that of 8LO, Melbourne. A good earth can be secureu by driving a length of iron pipe into the earth and keeping it moist. If possible, the connection to the pipe should be soldered. If the receiving set is used in a position that makes a short earth lead impracticable a counterpoise may be used. ‘This cousists of a duplicate of the aerial placed about six feet from the earth. ‘The same precautions that are taken to insulate the aerial should be taken with the counterpoise. All crystals are adversely affected by touching them with the bare fingers, It is best to handle them with tweezers or with a piece of cloth. The fingers leave a very fine film on the crystals, which weakens their powers. : Transformers must be kept well apart and the cores should be at right angles, although with the shielded type this is not nearly as necessary as with the earlier ‘open type. A whistle in an audio frequency transformer can be traced to several things, including transformers too close together and wires in these circuits being placed parallel. Incorrect connections to the audio frequency transformers will cause trouble even though they have been wired according to the markings on the transformers. Connecting the cores of the transformers together and earthing them will often overcome an elusive whistle. ; i

Me. A. J. Marston Bate, M.A, Intum., Mus. Bae., received his musieal education in England where he commenced at au early age to study the violin and ‘cello, and in New Zealand completing his ‘cello studies under his brother, Mr. Francis Bate, who is a pupil of the famous Johann Ifock, and is now resident in Auckland. We has played in every theatre in Christchurch, and conducted orchestras at the Theatre Royal and Crystal Palace theatre. For two years he has been solo ‘ccHo in the Orchestral Society, and for the last four years has been ‘cellist of the United Service Hotel trio, He is new at Crystal Palace Theatre. He has played "over the air" solos, obligatos and trios, the last in conjunction with the Christchurch trio. -Steffano Webb, photo.

[ X-ray plants are not infrequently causes of intense intezference with brceadcast reception, and if you reside near a hospital or a medical practitioner who employs X-ray apparatus you may expect some trouble at times in getting distant stations, There are, however, X-ray plants circuits which do not occasion interference with radio, Wood which is perfectly dry is an almost perfect insulator, but owing to its absorbing moisture its efficiency as a non-conductor is limited. By impregnating tvoed with wax it is possible to retain its properties as an insulator even in the presence of moisture. If there is a rattle in one of your. headphones, carefully remove the shell cap and slide the diaphragm carefully off to see that there is no dust or filings between the imagnet and the diaphragn:. Filings will ‘‘sticx’’ to the. magnet sometimes, and as the dia-. phragm vibrates, will cause noise. In comnecting up the headphones to the set see that the plus cord goes to the positive terminal of the B battery, and the other cord to the plate of the last. valve. |

A junior Melbourne station which the wriler has noticed has come into prominence recently is 3UZ. ‘The transmitter has been redesizned Jatelv, ae’ the aerial power of 25 watts has been increased to 500 watts. A ccunterpoise is used. It has been decided by the proprietors of 3UZ to place the station on a commercial basis, and to cater for air advertising. When considering the subject, the directors decided to take a bold step and adopt the American scheme of "sponsored progtemmes.’"? This method of advertising to a Jarge_extent restricts the banal announcement regarding the virtues of a particular product, and at the same time reta‘ls its advertising yalue by inducing listeners to tune in the station. In connection with the recent shortwave programme from 2FC, Sydney, which was rebroadcast in England, a feature of the broadcast was the laughing of a pet kookabnrra brought to the Sydney studio for the purpose of ‘langhing for Britain" by its owner, Mrs. W. Clarkson, St. Peters, Svdnev. Mr. Grattan Smith repeated the "Cooece"? calls, which were so well received in Britain during previons broadcasts. In selecting a variable condense: make sure that there is no Jost motion between the shaft and the bearing, o1 any shaky contacts. A ‘pigtail’ connection on a condenser is a commendable idea. The wireless plebiscite conducted seyeral months ago indicated that more than half the receiving sets in use in Victoria are made at home. Arrangements have been made by broadcast station 31.0, Melbourne, to encourage the work of home receiver builders and to provide them with facilities for the exchange of ideas. Tt has been decided to hold a competition for homemade receivers in a suitable hall in Melbourne in the near funiture. The competition will take the form of an exhibition of home-made equinment, which will be open for inspection by wireless enthusiasts for several days. In taking hvdrometer readings of vour wet A battery always be careful to return the lianid taken ont by the hydromcter to the same cell it was taken from. Failure to replace the liquid in the same cell from which it was drawn will result in destroying the uniformity of the cells. For instance, if the acid has been drawn from cell A and discharged into cell B, the ainonnt taken must later he made un by adding water, and the acid in cell A will be that much weaker, while that in cell B will be correspondingly etronvcer.