Show edited by 0 doublas editor of radio merchandising tam J to affey fig I 1 hookup hook up for double ground spark transmitter while the regular form of radio communication muni cation has been widely used in boy scout encampments encamp ments there are limitations which restrict its aae io fo those scouts more advanced in the art for instance the wavelength wave length regulations must be rigidly adhered to and special licenses must bo be se secured ared before the sets lets may be placed in operation the air cannot be used indiscriminately for or fear of causing serious interference with receiving sets for which the messages ore axed not intended thero there tg Is another form of communication which Is suitable for scout camps and which Is deserving of wider application the double ground system has been little used in tills this country although it was waa of immense value to the front line of the french army during the world war the transmitter Is so ao simple and well known as to require little explanation for its most important unit uelus Is the well known spark coll this instrument has fallen into disrepute la in radio to a great extent not only because of its gruff andun and uncertain tone but also on account of the poor tuning qualities of sets seta using spark park colls but with the double ground hookup hook up there Is no tuning required and since it Is useful primarily for slow speed communication the low note Is no obstacle in fig 1 appears the hookup hook up tor for R double ground transmitter the terminals of the spark coll coil are placed a fraction of an inch apart and a wire run out in each direction where contact Is made with the ground the longer these two wires the greater will bo be the possibilities for distant communication although though cl if they are about fifty feet each code conversation may be carried on over distances not exceeding one half mile if insulated wire Is used it may be strung on the ground although it it insulated it should be kept a foot or two off the ground by wooden stakes the grounds may be in the form of bf iron pipes about four feet long driven deep into the earth the better the contact of course the better will bo be the results in fact a short strip of chicken wire bur burled leda a foot or two beneath the soil Is ideal for the purpose connection No should be made to piping systems for that would destroy the possibilities of longer distance in fig I 1 Is shown a sample receiving circuit there Is 13 no tuning required R nil 11 that Is in needed being nn fin audio fre quency amplifier WD 11 tubes may easily be used with two dry cells for lighting the filaments this arrangement ment Is indicated and a single rheostat Is used the receiving arrangements bro are identical with those of the transmitting system as for far as the ground wires ore are concerned there Is an unusual advantage in the double ground arrangement in that it Is directional rig fig 2 shows a tal cal arrangement of double ground outfits at a boy scout camp there are let us assume one headquarters station and four outposts the headquarters station Is equipped with four grounds forming two double grounds 0 aa 0 fig Z of transmitting stations station with a double pole double throw switch connected so that either nitty muy be used first suppose outpost A to be ending on account of 0 the high resistance si 1 of the soil between the two grounds of station A the electric currents must of necea necessity sIty spread out materially mater lally in ili passing between one of As grounds and the other there Is a considerable difference of voltage between the two grounds us its any who happens to get tits his hands on the secondary terminals will testify I 1 therefore between grounds 3 and 4 of the station there will also be a difference of voltage on recount account of the weak currents set up tip by station A tile farther IQ Is from A the weaker will lie the currents current and etc re in the telephone weaker but suppose alq were to switch over to grounds i and 2 what would happen then since I 1 and 2 are both on the same line to A there v will be no difference of voltage and hence no signal in the telephones how convenient I 1 but with grounds 1 and 2 station Is all set to receive from station 0 O C whose signals were excluded in the first case and ID D might therefore be carrying earn ing on PL a conversation and at the same time A and B could start up and exchange some messages without bothering the other two at all of course it Is feces necessary sa ry to use the compass quite accurately as scouts are trained to do in placing the grounds to have grousd that will keep itself wet most fans in hooking coking fi up a radio outfit either have a poor aerial and a good ground or it a gool aerial and a poor ground almost always its a poor ground here Is A very simple way to nake make a good groV gend nd one that will keep itself wet for a iong time without hav ing ng to watch it secure a piece of galvanized pipe three quarters inca in diameter and 0 5 feet act long also a piece of two inch pipe LEA 0 M 4 eplee affa DA P I 1 D J three feet long drive the three ter er inch pipe into the ground about ono one oot foot fill the pipe with water and let it t settle then fill 1111 it up again the T 11 ie water ater in tile the two anch pipe serves to keep beep the smaller pipe full all the time and nd also keeps the ground wet n round around the he smaller pipe dick 11 II roberts roberta your receiving sets must be kept clean cleanliness find ne utness are important for effla efficient effluent ent operation of a radio receiving set dust should not be allowed to gather on the instruments for it causes leaks in the circuit dust between the plates of a variable condenser develops short circuits and collections of dust or soot on the antenna insulators make it easy for the radio currents to leak away to tha ground before they reach the receiving sot one operator noticed the signals gradually growing weaker ile he overhauled the entire set carefully inspecting spec ting all connections but this failed to locate the trouble lie ile began to lose falth in radio one morning while dusting about the room life his wife just happened to brush the dust off the spiderweb colls coils mounted on top of the cabinet that night the set worked to perfection as it did when first installed keep storage battery in proper Condit condition iori tile the following pointers will be helpful in keeping your A battery in proper condition do not allow the battery to become completely dl d always maintain the level of the he ta electrolyte acid and water above ue the tops of tile the plates usually one jirar ter inch i keep the battery well clarg aliard n at t nil all times as it la in difficult to revive a dead battery which hit has been standing idle for a long time do not allow the electrolyte to bubble over on to the tops of the cells it if this flits hn reduce the lie ch irgang rate app tho the top clean to avoid leakage ift 10 1 w q determine the gravity range of your particular battery and keep it within pr proper p cr limits by frequent tests with it hydrometer |