Show 01 00 a g m rya WIN 00 Is 0 am 0 00 a 0 w Z S 1 y edited by G dougla vur drop Li titor of italio merchandising the greatest greate zt thrill that a radio fun fan get Is to bring in a distant sta atlon on a set kiet that lie built himself tills this thrill Is greater if tile tho set can run circles tiny any other set as tar far ns as s selectivity la Is concerned tile the purpose of tills article Is therefore to bring before tile the fans a concise description of a set that Is easily constructed at home find and that will give satisfaction asfar as far as distance and selectivity are concerned in addition tile volume tills particular set delivers Is something to marvel tit at most or of tile the equipment for tile the set will probably be found in the lie fan workshops it if not then the money in dross ras fles rotor loc rk J how the windings are placed on stator and rotor vested in the following parts will not be III spent one coni composition position tube 4 inches in diameter by 2 indies inches wide one composition tube 8 3 inches lit in diameter by 1 inch wide ono composition tube 4 inches in diameter by 1 inch wide one composition tube 3 inches in diameter by 2 inches wide one niad variable condenser vernier it if possible one wa mad variable condenser vernier if possible one mad fixed condenser one vacuum tube preferably a but any tube will work one rheostat to nt fit tube one socket to fit tube one grid leak 2 meg one one quarter pound of no 20 26 so S 0 C 0 wire seaf seven n binding posts v one 7 fly by 12 inch panel four lots dials four 2 inch lengths of brass tub ing ii inch in diameter strip of 5 10 inqui brass one 2 foot length of flexible wire for pigtail connections phones batteries lind and some borne small nuts find and bolts tho the first step in construction is the winding and ars assembling embling of tho the colls coils upon tile largest tube 4 by 2 inch 40 turns are wound in this manner at tile the extreme edgo edge of tube the wire Is fastened find and 20 turns tire are wound on the exact center of the tube Is then found find and a space of 8 32 inch on either cither side of this middle mark Is left the wire Is then car ried over tills this space and the winding continued continue for another 20 00 turns which will give 40 turns on ibe the tube going in the same direction and with a space of 6 5 10 inch left between each 20 turns in tile tho center of the tube this Is for the primary the secondary tube the next tube to bo be wound Is tile the 3 by I 1 inch tube this tube Is wound 58 lope a C pic k showing details of couplers and shaf t arrangement with 20 turns in till all with the same spacing as the above tube has in the tit L center namely 5 6 10 16 inch tills Is for f or the secondary condary Be the 4 by 1 inch tube Is then wound with 20 turns and tile the 5 10 16 inch spacing in the center Is again carer carefully ully adhered to tilts Is also for the secondary secy y tile last tube 3 by 2 inch Is wound with 40 turns with the space in the center left as per usual tills this last winding Is for tile tickler cider ti fig I 1 shows the winding and spacing the 4 by 2 inch coll coil and anal tile the 36 3 by I 1 inch coll coil form one pair of windings the 4 by I 1 inch tube and the 3 8 by 2 inch tube form the second pair that Is the second half of the secondary and the tickler the larger tube in each pair to Is called the outside tube tuba or the stator and the sni smaller aller tube Is called the inside tube or the rotor in the exact center of each tube n ccarter inch hote hole much bo be drilled through both sides bides these two holes fire aro for tile the shaft of tiie the rotor ani should there therefore fole be directly OP opposite one another the brass strip Is allow now prepared to become part of tile the set first a 4 inch piece of it Is cut then referring to vis FIX A it Is bent in taj shape s shown on tile the stator stalo colt coll A hole la IS then drilled in each end for use in tho the couplers to the panel in the center of the strip a 1 ancl hole Is drilled for tho t to go through at a distance inch above find and below tills hole two Il binell liall holes tire are drilled for fastening tile the strip to tile alie tube the tube Is ulso drilled for t tho lie bolts bolta the next step Is to cut two strips of brass 1 indies inches long and cut a 0 14 inell liole hole it in tile center on either sides side that Is above and below it it small hole Is drilled for ft fastening tills this strip Is then placed inside of tile tho secondary cot coll 3 by Is 1 I and formed to lit fit the inside of tile the tubo as aa show n in fig 1 tile remaining 7 inches of strip Is prepared in the same manner as the one above with tile the exception of forming the last two strips which are formed inside the 8 by 2 inch tube instead of tile the 8 13 by I 1 inch tube each tube Is then drilled for the fastening bolts in fig 2 tho the couplers are shown assembled to do tills it Is necessary to first arst put on the brass strip that holds the stator coll coil to the panel then the strips that go inside of tile the rotor tubes tuber are fastened to their respective tubes the first rotor shaft la is the rear one tills this Is placed in the proper position and with about a half inch exi extending ending from tile the outside of tile the stator the brass tube and the brass strip inside the tubing are soldered together the other shafting Is then aln placed ced in its position the most practical manner to do tilts this Is to place tile the coupler on a panel and measure tile the distance tile rod roust must project 1 from the panel to take the lie dials used then solder the rod lod and the strip together the pigtail connections next in line comes alie connections these ure are shown in I 1 fig I 1 go 2 four 0 inell inch lengths of the flexible wire tire are cut from the original piece find and two pieces are used tor for I 1 each coupler two pieces are forced through each brass tube and the ends tire are soldered RA diagram of connections to be used with selective receiver to the ends of the rotor winding tile the other ends of tho the pigtail connections are used to connect the rotor to the external circuit the panel layout of the set should have the coLy coLv leri leril at the top of the he the couplers each condenser conde anser la Is underneath der neath the coupler it controls the primary coupler will of course go nt at the left edge of the panel so BO as to bo be near the aerial lind and ground posts in tuning the set it Is well that you do not condemn it too soon as its extreme selectivity Is often discouraging until one becomes familiar with tile timing lining tricks it if Is possible to use regular varlo couplers in this circuit but the results will not be as good the condensers should also be of the best it if dry cell tubes are to be used experiment peri perl ment with tile plate v voltage imago until you have found the best point shielding will sometimes aid if any cari capacity elty effects are noted the secondary condenser will probably be the one needing tile the shield the tickler control Is very critical and should be watched carefully in tuning distant stations it may be set nt at the ali 0 best for a certain hand bond of frequencies but when a station Is rec received elved there is a possibility of losing it it if tile the tickler Is turned too quickly new york globe |