WIRELESS NEWS.

Press, Volume LX, Issue 18183, 20 September 1924, Page 9

WIRELESS NEWS.

SHORT WAVELENGTHS.

A NEW RANGE FOR AMATEUR

TRANSMITTERS

(SPECL'.LLT WRITTEN' FOR "TZZ PRESS. ) (By Electra.) A possible solution of the congestion of broadcasting wavelengths is anticipated by U.S.A. radio officials as a result of the action of tho Bureau of Navigation in opening up four new hands of short wavelengths to amateurs. Radio supervisors have be<sn authorised to issue general and restricted licenses to amateurs to permit tho use of the bands 75 to SO meters, 40 to 43 to 22 meters, and 4 to 5 meters for C.W. purposes. At present the amateurs use the hand j to 200 meters. The principal object of the opening of the new bands to amateurs is o permit of experimental work. '•'lf wo can deviso means of using the short wavelengths, f ro 1" r' 0 . „v----meters," savs Mr Terrell, Chief Radio Supervisor, "wo can put more stations on them than can bo put on the band 300 to 1500 meters. On tho longer wavelengths, stations must be two, three, and sometimes four meters apart to prevent interference. On tie short wavelengths they can be put half a meter apart. General Electric Experiments. Experiments already have been conducted by the General Electric Co., on tho fifteen and sixteen nieter wavelengths. While these experiments were not entirely satisfactory they showed the possibilities of the short wa^olencths." » , Many of the thousands of amateurs throughout tho world are ecjuipped, both financially and technically, o experiment with the short wavelengths. Reports have been published showing that good work can l>e done 011 these very low bands. About a year ago the Radio Society of Christchurch did some experimenting along these lines and results were very satisfactory indeed. , One of tho advantages of these low wavelengths is that the amateur will not be required to observo silent hours wMlo broadcasting stations are transmitting. AF. TRANSFORMER FAULT. It is commonly assumed that transformers always break down because of overload. Oftentimes, however, the cause is far different. Tho windings of an audio frequency transformer are called upon to carry comparatively heavy low frequency impulses of varying audio frequencies. The louder the signals the stronger are these audio frequency impulses. If the windings of a transformer were microscopically examined whilst audio frequency impulses of varying frequencies were flowing through them, it would be soon that they were vibrating in sympathy with the frequencies they were passing. If the windings have not been designed bearing in mind the conditions of service, although tho effect of the vibrations might not be immediately obvious, the ultimate effect would be to alter the molecular format-ion of the copper in the windings and render the wire crj'stalline. Once windings have reached this condition, it is only a question of time before the user will one day he surprised to find his transformer no longer functioning. Unfortunately, even expensive transformers axe not immune from this fault. . Repairing a Breakdown. The owner of a transformer that has broken down will l do well to find out first what a rewind will cost, as in a great number of cases it is cheaper to buy a new transformer than to have the old ono repaired. Another fault that has been cropping up of late is the breaking of the fine wires of the windings where they aro soldered to the four terminals. This is caused, to my mind, through the use of "flux" that has some acid in it that sets up corrosion in the fine copper wire, and in a short time makes the wire too thin to stand any vibration. It is just ■as well, when a transformed refuses to amplify and a test shows an open circuit, to have a close look at any of the soldered joints before discarding tho transformer. Incorrect Windings. Still another common fault is the incorrect connecting up of the transformer windings to the terminals, by the makers of the instrument. Quite a number of cases lias como to my notice where the secondary winding has been connected to the primary terminals and vice versa, or perhaps, one secondary lead connected to a primary terminal and the other secondry lead O.K. If you ever come across a transformer that reduces the signal strength instead of amplifying it, givo tho connexions the "once over.'' Never believe tho ticket that is generally attached to the transformer by the maker, stating that it has been tested by "so and so" and found O.K. I have learnt my lesson and am handing the tip on to piy readers.

RADIO ON TRAINS. A successful radio experiment was recently conducted in England by the Radio Society and- tie L and N.E. Railway. A wireless station, capable of receiving and transmitting messages on a wavelength of 185 meters, was installed in ,_a rear coach of tho 7.30 p.m. express from King's Cross to Newcastle, going at a, rate of (30 miles an hour. As it sped .ilong, messages sent by various amateur experimenters according to instructions were received. Musical selections from broadcasting stations were picked up. The primary object of this experiment was to note' _ the effect that tunnds, cuttings, bridges, ore-bearing localities have upon wireless signals. Signals were entirely lost going through tunnels and passing over limestone rock.

HERE AND THERE. An American economist lias estimated that tho people of tho U.S.A. will spend approximately 350,000,000 doltirs 011 wireless equipment this year. Greatly improved results would, be obtained by many amateurs it they did not use so much metal in the construction of their sets. Masses of metal "absorb" signals owing to hysteresis and eddy current losses. l' or this reason all met a I parts should be j kept as small as possible. Only the ! thinnest and smallest screws possible ! suould be used. Nuts shculd also be kept small. Details like these, in themselves may appear to bo unimportant, but together with other small improvements better reception may result. Tho Germans make sets that have only ebonite screws in them, tha total amount of metal being rcduocu. to a minimum. The fine installation on Senator Marconi's yacht-, the ''Elettra," inl eludes a duplex telephony set with

which it is possible to transmit and receive simultaneously without ''switching over." Listening in to 2Y"M last Tuesday I was sorry to hear that he had started at 4YA's nasty trick of slowly fading in and out. It is to bo hoped that this fault will soon bo remedied so that we can enjoy fully his ideal modulation and items. Dr. James Rogers, father of underground and undersea radio communication, has just celebrated his seventyfourth birthday. Dr. Rogers is busily engaged in attempting to devise a method of underground broadcasting. There are ponding at present in the U.S. Patent Office "60S applications for patents on radio inventions. Some of these applications are several years old, while same of them are at least a year old. BOOKS. The publishers of the N.Z. Wireless and Broadcast News have brought out a "Radio Amateur's Leg Book and Guide," which sells r.fc os a copy. It contains full particulars 01 time signals, weather reports etc., and a list of short and long wave stations, and tho time of transmission. A list of the high power stations of the world, stations in and around New Zealand and: Australia, ships-' call letters, amateur stations, and broaden stir. 3 stations is given. Th« most important part- of the publication, however, is tho log, in which adjustments arc recorded by the person receiving or transmitting. All columns appropriate to tho purpose are given, and the headings aro an invaluable guide to necessary entries. A scale of notation for tho strength of signals is given. The first copy of the "Radio Journal has been issued this week. This little book is the official organ of the Radio Society of Christchurch and is gratis to members. Non-members can obtain ■copies from any of tho leading radio dealers at one penny a copy. This is the best club magazine that I have seen to dat&, and contains some very interesting and instructive articles. Tho second edition of Scott's Radio, handbook is out and is a big improvement on the first. This book contains details of the construction of Lowloss and tuners, and quite a lot of other good data. The size of the book has been nearly doubled and it now sells at Is 6'd a copy at all dealers.

NEW RADIO DEVICE.

BATTERIES ELIMINATED.

(raoil. OtTB OTTO COBBBSroSDXKT.)

SAN FRANCISCO, August 30.

Revolutionising - radio reception, in the elimination of the "A," "B," and "C" batteries, customarily used in receiving sets, a new device, the invention of George E. Crouse, New York radio engineer, has been introduced in America to the radio world under the name of "Run-a-Radio." '

The great drawback to using house lighting current for the operation of •radio Bets, which lias been the dream of radio enthusiasts for years, ia the fact that such current, is usually of. an alternating nature. The lium caused therefrom is amplified to a disagreeable extent in radio sets when such current is used in receiving. Undoubtedly radio fans in Australia and New Zealand have experienced this difficulty, but in the '' Eun-a-Radio" circuit the current from tho light socket is rectified and changed to a direct current of low voltage, suitable for "A," "B," and "C" circuits. The.apparatus by which thi3 is accomplished plug 9 directly into tho light fixture on one end and the radio set on the other. It lias no moveable parts, and makes no noise. ... The use of the new device ehmina»es the resistance, which ia one of the drawbacks of the "B" battery use, and permits of tho connexion of lamps in series instead of. parallel, thereby cutting down the wiring of the radio set and increasing its efficiency. The discovery, carried out by Crouse after long research was submitted to Milton B. Sleeper and Professor John 11. Morecroft, in charge of tho electrical engineering division of Columbia University. Morecroft, who is president of the American Institute of Radio Engineers, declared it to be l one.- of the most ingenious inventions of the radio year. In radio sets which use the house lighting wires' for an .antenna,- 'the same wires used for reception also deliver current for the operation oi the set when a " Run-a-Radio," so that no Outside aerial installation is required. While the new device does not mark the death knell' of tho battery, which will always be a . necessary attachment for portable sets, it simplifies the home receiver down to a brace of boxes—the set and the rectifier. Standardisation of the device lias been undertaken by the Rader Appliance Company of . New York, which lias conducted exhaustive research, work along lines laid down by Grouse in his original investigations. Crouse, the inventor, has been identified with U.S. Government activities in connexion witli the gyro-compasses and gunfire-control apparatus, which was used extensively, by the United States Navy. The '' duplex compass'' is another of his inventions, and iS a .device for giving accurate indications of a ship's heading under fire.