Show 7 by PERCY WARREN in radio world wo we all knoer that a not which la Is built of expensive materials works very well and Is recommended by all experts but suppose that we the money to purchase pur haae chave the best new parts by that I 1 do not mean that we use materials efficient electrically and still atall expect to got get very good results what I 1 mean la Is that wo ax can build our own coll coil at a very small cost coat and still obtain efficiency of all the sets that give distance cid and volume there IB fit not one ona that excer tho the simple regenerative type there are many types of 0 regenerative sets acts the single circuit the double circuit end anti finally the triple circuit there was oven even a four circuit set bet with several ise vernl controls con trola of all four types there Is no one more popular than the three circuit tuner this circuit deserves its popularity because it t la Is selective and gives volume tho the set that I 1 am going to describe to iff of the three circuit variety and la Is a world beater for volume and distance ven even though the inexperienced person can cam build it construction of tho the coll tho the first thing that you want to do before you build this set Is to read every piece of data that refers to the successful operation of tho the receiver you have probably read the information already after doing this we are arc all ali set to build tho the coll coil which la Is very dimple but with which a great deal of caro care should be taken procure a form about four inches in length three inches in diameter we will wind the grid coll coil first starting about one fourth of nn an inch from one end or of the form before doing this better drill two holes about three six of an inch in diameter and about one half of an inch away from each other for anchorage put binding posts here and mark one 0 and one IP plus plug now drill two holes exactly us as tho the ones drilled on the other end S 9 diagram showing circuit of tuned plate regenerative set of the form put two binding posts here and mark posts P and it plus on this same side about two inches kway away drill two more holes of the same dimensions as aa tha four others tho the bt beginning gInnIng of tho the grid coll coil winding goes to n post marked 0 and lettered na as D on the diagram continue winding 60 50 turns of no 22 single cot ton covered wire and put the end of tile the coll coil to the tha post marked A plus leave half on an irich and put the lie beginning of this new winding to the post marked OR GR B D in diagram continue winding until 10 turns havo been completed connecting the end to the Ille post marked A plus id d in diagram leave one fourth inch now ind and place the beginning of the wire to the post marked 11 B H in diagram continue winding until 85 turns have been awn made connecting the endom end of the wire to the last post which Is marked 11 II plus F in diagram male sure that all the windings are arc in the same direction and that all the posts posta as designated panel instructions lay aside tile the coll and take the panel there are two controls on tile the front besides the rheostat which should be of the gohm G 0 ohm ahro type for WD ll 11 or 12 tube the panel la Is 7 by 10 30 inches and Is of hard rubber which Is more efficient for radio than tho the beautiful looking bakelite panel drill a liole hole for the alie variable condenser 25 0 6 inches away from the end and 8 ai incites inches from the top tell of the panel tile the templates for tile the condensers tire are in n tile the cartons car tong the condenser Is the only article which costs costa tiny real money malley the alie dials are three incites inches in dinin eter the baine dimensions apply to the other variable condenser when drilling the holes for tile the rheostat drill 1 inches from the bottom anti anil 4 incites inches from the end the other dimensions are given with the rheo atilt tnt that la is all the drilling that boea on the front of the panel ex the baseboard holes winch which are determined by the alie size of tho the board that you have usually an inch thick board about six inches in length find and having buying about three holes evenly 33 31 3 inches space on the board mount the coll coil between the two condensers dont squeeze it in assembly directions at ai the extreme end of the board place the terminal strip the strip which consists of the battery binding posts and the ant antenna and ground posts directly in back of the coll put the socket if you decin n jack too expensive a pair of binding posts inny bo be put on the terminal or on tile the panel and the tips of the phones phone put there the other materials include ca mad fixed condenser gl al nicil fixel two or grio grid leak now for the lie wiring of tile SO om rieca the post marked A in datil r 11 md nd mi at cai to the and the post m marked OR OH to the round the F plus 0 b in diagram goes to the positive post of the ho socket and to the plus post of tho the A battery which la Is connected to n B minus tho the terminal marked 0 on coil goes to one olde ada of tile the grid condenser and to tho the grid leak tho the other end of tho the grid con i denser goes to tho the grid post of the socket rocket tho the term tennar al marked 11 I 1 in diagram K H goes to the plate post of tho the socket bocket the last terminal marked B n plus pius in diagram F goes to one end of the condenser whose oth other end goes to tile the B plus across the terminals of 0 both tho the plate and the grid colls coils connect two variable condensers making sure that the rotor plates of the grid condenser go to the A plus and tile the rotor plates of the condenser which la is shunted across the plato plate coll coil to the n B plus side bide ot of the plate coll coil all this wiring should be done dona with no IS 18 bell wire or rubber covered telephone wire avoid bus bar that completes tile the wiring ot of the set aerial advice your antenna should be at least 70 75 feet in length well soldered und jour leadin lead in ln should be put about one foot away anway from the wall well insulated your ground should bo be fla short its aa possible and should consist of 0 no 14 rubber covered wire tho the antenna wire should be no 14 4 hard drawn copper wire the aerial should bo be at least 20 feet above the level of the ground and at least 10 feet above tho level of tile the root roof but if you havo have a tin roof place the antenna nt enna as high as aa 25 feet which must bo be done in order to get away from the good grounding qualities of the tin trouble hints if you are getting nolay noisy reception first push up the prongs pronga of your tube socket clean tho the terminals at the end of the tube with sandpaper and test your n D battery with a pair of phones if when ahelf you put the phones across the battery you hear bear a lot of rushing noise you can be sure that the butof ey Is no good test teat your bypass condenser which la Is the contender condenser con denaer dender having a capacity of ined as this is 1 often shorted ehor ted |