RADIO TOPICS.

New Zealand Herald, Volume LXI, Issue 18601, 8 January 1924, Page 4

RADIO TOPICS.

BT THERMION.

BSOAD CASTING.

Wellington Broadcasters, Ltd., claim the distinction of being first in the field both at Home and in Australia and New Zealand to introduce Miss Gertrude Elliott and her talented company to a broadcasting studio. On last Friday week Miss Elliott (Lady Forbes Robertson), assisted by members of her company, broadcasted the first act of "Woman to Woman," which was < then being produced at the Grand Opera House. This entertainment, along with all others given by Wellington Broadcasters, Ltd., has been the subject of much favourable comment by all those who are fortunate enough to be within range. Their broadcast has for some time past been of the highest standard, and it is much to be regretted by local listeners that only the low power of, 15 watts is used, a power not likely to be increased until finality is reached in the proposed new broadcasting regulations. Last month a wireless and electrical exhibition was held in Sydney under the auspices of the Wireless Institute of Australia. The exhibition was an unqualified success as would be a similar function held locally. Prizes were awarded for various classes of amateur transmitting and receiving sets and the number and quality of the entries was very high. Such exhibitions encourage the amateur to build neat and efficient sets, and also give dealers an opportunity to display their parts and sets to best advantage. If the idea were acted upon locally there is little doubt that it would serve to introduce "radio to a riublic who are now showing an interest in, and who are ready to make a hobby of, radio broadcast reception.

Sydney Broadcasters, Ltd., will be providing entertainment for the New Zealand listener in the coming winter, and they held their official opening on December 13. The official opening was quite successful and several Sydney theatres installed receivers specially for the occasion. This station is to provide a "free" service, in that listeners on the particular wave-length (550 metres) will not contribute to tho support of the station except voluntarily.

LEARNING THE CODE. A novel method of teaching students the Morse code is being tried out, apparently with much success, by the United States Navy Department. It had been noticed that there was much greater efficiency in buzzer practice reception just before retiring than at any other time of the day, and the experiment has been carried further by allowing students to doze with head phones on when an operator is sending the code. The results have shown that remarkable, and in some cases phenomenal, progress is made in learning the code. Students of psychology would explain the effect by saying that the mind is divided into two parts, ' the conscious and the- sub-con-scious. '_ The former controls reasoning and volitional actions such as movement of parts of the body, seeing, hearing, etc The sub-conscious mind controls automatic actions, such as the beating of the heart, and it is further characterised by an almost perfect memory of things Impressed upon it. While awake and listening to the code irrelevant thoughts of the conscious mind interfere with the roceptiveness of the sub-conscious. While asleep, however, there is no such Interference, and hence a facility in retaining the code characters heard.

THE LOTTO SPEAKER. The best brains of the radio world have for some time past been endeavouring to design load speaker as such a piece of apparatus has been much desired since the advent of broadcasting. There are a number of problems to be overcome before it can be invented, and their nature is such as to give little wonder that the difficulties have as yet been insurmountable. The most important difficulty is # that due to electric distortion which occurs owing to the habit of any electric curcnit for speech transmission to remove notes of certain frequencies from the sound. This destroys faithful reproduction. Another difficulty is that due,, to magnetic distortion owing to the imperfect magnetic properties of iron and any arrangement containing an iron core responds more Readily to certain frequencies than to others. Further the diaphragm has to be considered, for its tendency is to introduce one particular note to which it resounds to the exclusion of others. Similarly the horn of the loud speaker shows " resonance" effects. Finally there fs the imperfection of the auditory apparatus, the human ear, to be considered and the designer of a loudspeaker must .take the particular defects into consideration and endeavour to produce an instrument having so clear a tone, and so perfect a reproduction, that anyone can understand it, even people who have really only about half an ear to hear with.

The design of radio apparatus has in no way reached standardisation, and frequent changes and improvement from time to time may be expected. The valve offers a wide field for improvement in efficiency > and a step in this direction is made by the " Sodion" valve described last week. This valve presents some novel features beyond its utilisation of the unusual properties of the sodium ion. It is a dry cell tube having no grid and therefore no grid leak and condenser is required. It gives a crystal tone reception and is said to be very senitive to weak signals. It is to bo marketed in America this month, and should be "the coming detector for broadcast reception. As it will not oscillate some kind of external heterodyne or chopper will be necessary for the reception of continous waves.

NOTES AND HINTS. As testifying to the value of wireless direction finding apparatus on board ship, it is interesting to learn that the Marconi International Marine Communication Company have been instructed to fit directionfinding apparatus on all passenger ships of the Cunard fleet. The premature announcement that the disaster which overtook seven American destroyers on the Californian coast last year was due to errors in the radio bearings was seized upon by critics as showing the unreliability of wireless D.F. Subsequently, however, it was shown that the wireless bearings were absolutely correct, but as they did not agree with the figures of his reckoning, the commander or the squadron ignored them. Tradition dies hard, and it was unfortunate for the commander and all concerned that when the wireless D.F. apparatus indicated a position different from tho other method of reckoning he assumed that the former must be wrong. Although the theory of the effect could not be given here, it is interesting to point out that it is not generally known that when a valve is in operation, one end of the filament is at a much higher temperature than the other. So that the life of the filament, may bo prolonged by occasionally changing the battery connections. When valves refuse to oscillate it is bad practice to largely increase the filament current as this will decrease the life of the filament. Usually the fault-lies elsewhere. For aerial insulators the porcelain type are excellent for reception purposes. Tho porcelain must be glazed. Only the best of composition insulators should be bought when it is desired to use that type. In the cheaper type the end rings, to which the. wire is attached, may pull out, causing the aerial to fall. The insulator should not be of a material which will absorb moisture.

ANSWERS TO CORESPONDENTS. C.8., Matamata. The license is not transferable. Write to the department. Your crystal set should receive IYA at 10 miles. Impove circuit by putting a fixed condenser of .001 mid. across phones. ,