RADIO LOG BOOK

Evening Star, Issue 23451, 16 December 1939, Page 4

RADIO LOG BOOK

NEWS BULLETINS The 8.8. C. news bulletins are now broadcast in 17 languages. Prior to the war the number of news broadcasts each day was 17; now the total has expanded to 49. The service is no longer styled Empire but is known as overseas. WHY " DAVENTRY 7 ” “ This is London calling, in the overseas service of the 8.8. C.” New Zealand announcers persist in referring to the bulletins as Daventry news. The 8.8. C. is still operating from London, Daventry standing in the same relation as Gebbie’s Pass does to 3YA. Underground studios have been constructed at Savoy Hill, and the metropolis will have to be in a bad way before it will be necessary for the broadcasting staff to move. A.B.CG PRODUCTION The Australian Broadcasting Commission has commenced the publication of a weekly journal, ‘ The A.B.C. Weekly.’ It consists of 80 pages, and includes station programmes (national and commercial), world affairs, women’s section, sport, short stories, and humour. It will bo interesting to note what effect its publication will have on privately owned weeklies which in tho past have held the programme rights. AUSTRALIANS OF LESS VALUE As the days grow longer and the nights shorter Australian broadcast stations are becoming less valuable to New Zealand listeners. Usually they are not satisfactory now until 10 P.m, or thereabouts. Short wave enthusiasts miss the Sydney transmitter 2ME which was ordered off the air when war was declared. The A.B.C. short-wave 3LR is practically off the map until 5.30, its output being too low to enable it to compete with the high-powered transmitters in other parts of the world. FITTING SCREEN PENTODES When fitting a screen pentode in place of an ordinary diode detector, it will often be found that the set oscillates at the bottom of the short wave dial when reaction is turned to a minimum, due, of course, to the readiness with which this type of valve will oscillate/ To avoid tampering with the actual reaction winding, d resistor may bo placed in series with the coil, between plate and coil. Its value can, of course, only be found by experimenting, but 1,000 ohms is suggested as a starting point. A resistor of the composition type should bo used, as, generally speaking, wire-wound resistors are unsuitable, as they are to a certain degree inductive. SAVE SPACE A handy space-saving dodge, using glass jars with screw tops, can be made, in which the usefulness is accentuated by having all articles contained in clear view. All that has to bo done is to drill three holes in each cap and screw these to the underside of the shelves, fill the jars with nuts, bolts, etc., and screw them into the caps. Now there is a neat row of containers whose contents can be seen at a glance. A good idea is to put small accessories such ns nuts and bolts, etc., in large jars under the shelves, and use jam and honey jars for valve sockets, resistors, fixed condensers, etc., and fix these conveniently under the bench. SHORT WAVE CAR SET It was inadvertently stated in this column that there were no short wavo radio sets available for cars because of interference. It has been brought to notice that there is a set of this nature operating in a Dunedin car, which gives even better performance than the ordinary broadcast sets. It has three bands, and the only difficulty is a slight one—it is rather hard to tune. The information given previously should have referred to America, where it is prohibited by law that short wave sets should be carried in private motor ears, since tho police bands aro on short wave. Only in California are short wave sets allowed. The benefit of short wave is that there is little electrical interference, and Daventry can be hoard in Dunedin in tho winter time during the day ou this particular sot, while in summer it can bo picked up during any night. * GROOVING RIBBED COILS Very efficient grooved, ribbed short wave coilformers can be made in the following manner. Only expensive ones are grooved to take heavy gauge wire: Anyone who has tried to file grooves in these formers know what a tedious job this is, but all that is needed is a large nut and bolt. The bolt must have the same number of threads per inch as the turns per inch needed for the coil. A iin Whitworth bolt has 12 threads per inch. The bolt must be heated almost red hot and then gripped by the nut in the vyce. Now the coil former is pressed against the bolt; the result is grooves are neatly burned into the rib of the former. The bolt is given a sixth part of a turn,, and the next rib grooved in the same manner. This process is repeated, giving the bolt a sixth part ’of a turn each time until all the ribs are done. By turning the bolt each time the slots in the ribs will be in the form of a thread, Tho slots can be deepened if desired with a three-cornered file.