| Show beam radio plan to reduce costs short wave system of telegraphy le put into operation that the cost of inter continental communication nill hlll gril dually be lowered there can call be little doubt vilen we consider the almost alino at y ad ivancs in fit the art of radio transmission one of the latest developments la a the short wave beam system of telegraphy which was recently IL I put L into inlo operation by the marconi company between england nod canada in with the widely us aed ed tong long wave radio stations which have been used for intercontinental inter continental communication muni cation heretofore the new short wave beam installation Is a mere pygmy in size and in power used an article in radio iladio broadcast mas ielne describes a beam station ns as consisting of five foot masts while the transmitter operates with tin nn input of only 20 kilowatts the transmitting frequency Is 1150 kc he 2009 meters the radio corporations station at rocky point by way of contrast lias has twelve foot masts slid anil a power of front to lff kilowatts kilowatt Is employed twelve masts feet high with a power input of kilo watts are used by tile the british post office wireless station at rugby england i ten towers feet hilgh with an input of 80 kilowatts comprise the installation at buenos alres aires in the Argent argentine lne all of these stations use ery long wave lengths kilo cycles to 1715 kilocycles kilo cycles to 1700 meters many other large stations alond could be cited ns as examples in this class it eon can readily be imagined that the economies affected liy fly tile new bearn beam system are of considerable magnitude not only from the standpoint of initial cost but also of maln maintenance teri te nance once the speed of trans transmission and the reliability are also considerably greater lit in the new system concentrating the waves i concentrating the radio waves in ft i I 1 beam instead of allowing them to wander to every point makes it possible to use 20 kilowatts instead of the or more required in the ardi nary long waie wae system in spite of the fact that less power Is used at the transmitting station more cuore power tandem systems tend to reduce controls the tendency to reduce controls by tandem m tuning I 1 which I 1 lias urs been gaining more fa faor as it lias has solved its problems la Is one 0 of the predominant features of the 1927 tuning circuits writes zeh bouck in a recent issue of radio broadcast magazine tandem tuning refers to the mechanical linking of two or more tuning units these units generally consist of united condensers den sers with rotors mounted on a common shaft revolving through individual stator staler plates built into inlo a rugged extended frame work the isolated but simultaneously varied capacitances are connected to nal circuits one ano three or more r t f stages and detector the lenig associated with tandem tuning have boon been the matching odthe various inductors and capacitances for really successful suc ceri tandem andem tuning it Is s essential that the inductance or coll coil effect of the different circuits and and the capacity pr or condenser effect be ibe some same at all iwae amo lengths tills this means 8 that lutt in complete seig gels employing tuning the stray capacity and inductance caused by ing inc and the of parts must be exact exactly lype the same in oil all audio judio frequency fre duelley ell circuits cults a balance that til inese lese only recently attained arthe art of rudio radio pi production tia up of iier vernier iller condensers can compensate for the discrepancies in capacity lint it if employed to cor eject condenser or coil discrepancies those les e vio riders fre re in effect pl PI controls for llie be compensation differs fo for every setting of of tile main I 1 dial an clation of tile difficulties In anted ted I 1 li the tandem tuning of three ellel circuits lits cods its expression op tile list patt bof of ilia ile lu in two la Is delivered to tile the rc recoiling eling station and that Is the goal all radio beers rs strive for or inthe arrangement of the antenna system at boddin bodmin Bodt oln rn england gland the antenna wires ore are disposed so us as to constitute grids parallel to each other the antenna wires being energized simultaneously from the transmitter nt at a number of feeding points through a special feeding system so as to intire that the phase of the oscillations lit in nil all the lie wires are anre the same the antenna and reflector wires are vertical while horizontal wires are used as aa supports there are 10 16 antenna wires find and 32 reflector wires to each span id and there are four spans at each station two fur a transmitter operating on kilocycles kilo cycles 2009 meters and two tuo for a mitter which will operate on oil a bit ghaly higher wavelength not yet determined proved by calculations it has been proved by calculations and by experiment so t the ie author of the radio broadcast article kenneth B humphrey tells us that the directional ellece of suh an a arrangement r ran gement Is a fun buntion function tion of its limen relative to the wave lengths used therefore the shorter the wave length the smaller the antenna H H R reflector wires two to each C antenna wire R A wires C C C I 1 A A 8 y y antenna Wres goto coupling box copyright radio broadcast t diagram shows one span of sixteen antenna and thirty two reflector wires there are two such spans for each Trana transmitter mitter or four for each station system and consequently the less cost besides the actual decrease in physical dimensions the properties of short waves are such that long dis can be easily spanned dy by the use of reflectors at both the sending and receiving ends the wave Is projected out in a narrow beam and is cau caught lit at the receiving end by a similar reflector and concentrated on the receiving antenna tills this stops up tip the signal strength and permits the use of much lower power sill nil of which has a direct bearing on the cost swinging signals not always due to aerial swinging signals are not always due to the aerial sometimes a ground connection may be at fault this Is one spot that Is oyer overlooked looked and one that should be given the once over periodically due to the gai action due to dissimilar metals the ground t lection seldom remains clean and it a dirty connection means less volume from distant stations most any old thing will do for local and nearby reception but it Is all the little points that make distant results possible ways in the development of localized control cont iol and the design of re receiver elberg having two controls instead of one control the localized idea Is perhaps most familiarly familial ly illustrated in the R C A super heterodynes the oscillator and tuning dials in fit the form of closely parallel drums are so arranged that they may be turned together by a single motion of one hand however either dial ca can be turned separately permitting those one fine tar lations of ft n degree or two tuo which are essential to efficiency on uncompensated circuits A k somewhat similar arrangement produced by another concern is now avol available lable to the he constructing fan three condensers of it modified straight frequency line tyl type ille are mounted t concentrically with to the panel rather perpendicular to it the three condensers tire are not mechanically linked ord and each Is controlled individually by its respective dial however all ali throe three may be turned simultaneously by two fingers placed upon tile the center pc ies scales rending reading from zero to one hundred depressed in the alua are supplied as standard equipment but these are easily altered and such sp special designations descg as wae wavelength length breque bicy or call letters can be substituted to tc suit individual needs concludes sir mr bouck radio being simplified radio Is bell belaik greatly for set builders also tor for those ullo mho like to 10 circuit cho changes inges in in sets that hint tire lire not too carefully hidden beneath and shields eldi one of the handiest of 0 tile the now new things that can be hought bought at accessory stores atom s Is the con nector for making a T connection another helpful thing Is the battery lead tag clamp one of 0 these if little it I 1 e tags to tile th wire ond and there Is no get ling biting it confused cont used with elsi |
