WIRELESS.

Hokitika Guardian, 4 January 1923, Page 4

WIRELESS.

GREAT IA NEB'S OUTFIT. WONDERFUL KFFICJENCY. j In the early days of wireless—before the word radio had come into vogue in the present connection —the. new ait of sending messages through the etliet was thought of by the average layman as applicable, for practical purposes, almost exclusively for ships. Latterly, we have heard so much about broadcasting and the amateur’s use of radio that the nautical uses of the developed art have been quite in the background ol popular interest. But when the announcement was made of tiie arrival in New York harbour ol the largest skip in the world, the White Star liner .Majestic, the question of the radio outfit carried by this new sea monster nnturallv came up for consideration. In the New York "Tribune” appeared ihe following interesting account of the very up-to-date radio outfit of tbe now liner YTitbin a comparatively small space j in the wireless cabin oi the world s ; largest skip there is installed one of Die most complete, compact, and efficient v.irelos systems yet devised. The. el,'lit ship lurries two types of transmitting equipment and two types ol I receivers. The transmitting apparatus j consists of a 1! kilowat queneh-gap ■mark -et and a continuous-wave trails- ; critter using one big vacuum tube with •in output oi It kilowatt. The range of the quench-gap set is approximately in;- 'idles, while that of Die continu-ous-wave set is in the neighbourhood i. f .1000 miles. i The receiving apparatus consists ol i a complete receiver with a wave-length range covering everything now ill daily ii-e and a radio-goniometer, or direr-iion-tinder. The latter is probably ' the most unique of the radio equipment aboard, and differ* materially from the j standard American practice in that it: utilises Iwo loop aerials ol extremely large dimensions ,permanently rigged ( ,n the ship, in an unvarying position. I At the first glance it might seem sojierlluoUs to install a spark transmilter on a ship when its efficiency, as compared with the continuous transmitter. is so low. In this connection ii must lie rememherod that continuous waves are extremely sharp in their tuning, while Die spark is much hroad- | Under Die cireutusl ances. therefore. the spark is much better suited for tl-e purposes of sending out general call . and particularly si lor sending out Iha distress call. ! u audit 101 l to this, the two types ol I r - 1: sm ii• ieg apparatus naturally tall into two well-delined spheres ol UseI'nbiess a. heard. The eenliiuious-wave :-e! oper 11cs i'll wat " lengths. Hinging !. I we"!! 21HH.1 and "AtMl metres, ami is ! v. ill suited for communicating wit h i :he long-disl erne shore station-. The uueneh-gap set is a i toned io the standard diort v, a-. e ranges set aside lor -ii, ! v D:e International Radio Goii- -, mu ion and is suited for xhip-to-ship 'amniii'-aiici! and the ordinary form of •■hip-tu-shuro work. The e lit ill!-.on--wave set operates on a!!» : si■ ing current, which is reclilied bv t.w*.i el-men! rectifiers, of which there arc lv..’ oi-lulled in the (.>>. [a,!-ei. The osi'iliating tube Las an culpa* oi j .■"!!' Iwai is, I lie 1 1 a.ii-iui ill ug '•*,i:iniHo'it is oomph i".i by the addition . • a dotl-;vat: auxiliary quem-h-gap set ties*-., eed for emergency purp'"Os. THE RECEIVING BET. ; The regular receiving equipmeiu, while very sensitive, de.es not depart ''.■a, standard practice. Ii is in the radio-guaimetcr, however, that the cbiel interest in the apparatus aboard ilir Majestic In-- ibis consists ot a spot iai type of receiving transformer, ; a I a siva Ive aiiip!ili-.’i'. The latter j. tour stages of radio frequency amplification. one detector-bulb and one siege oi audio frenqiieney amplification, in a- the English call it. a note mng’j im remarkable thing about Du's amid! i,• r -et is that all of the six bulbs ere controlled by one rheostat and a potentiometer which controls tbe initial grid potential of all six tubes. The audio frequence section ol the omplitier ( an he swiieln-d out of the circuit if not required. This is arranged when taking bearing on stations that are comparatively close. ,-\s has already Ecu said, the loops ic-e-l in conjunction wnli the direction- j finder are quite novel. They are based , on tiie Belliui-Tosi system, and consist, , mi a iinvartship loop and a fore-and-aft I- op rigged up close to the wireless cabin and supported in a manner that Las now become standard on British ships. - With this apparatis. the wireless J opera tor hveniiies an important factor : in the navigation of the ship, especially : in foggy weather. With his aid the ; position oi (la- ship can he determined ■.DDiin a verv few minutes by taking hearing-- upon well-known land sin. '■ Dens, as all of the latter are listed in if... internaiional call hooks with their exact latitude and longitude. It is aNo possible to toll the exact bearing of other ships. i in foggy weather it is possible by means of the direction-finder to defer- j mine roughly the distance of another ship, while i's direction can be deter- ! mined with exactitude. This is an im- . portaut i'unetou, and one bringing a j new factor for safety to navigation, as j ii will tend to reduce collisions at sea : during I'ug. fn addition to this, the ■ direction-finder has an important use in hadlv congested wireless areas, such ns in the vicinity of New A ork harbour. , In these ease', where interference is ; very had as a result of so many sta- j Dons attempting to work simultane- - on sly. Die operator can change over to ! his direction finding apparatus and use j it for receiving purposes, thus cutting ; out all intereference except that which emanates from the same direction as . the station he desires to listen to. J