Show 1 doted I by 0 douglas Ward iop koltor of badii Z TUBE CIRCUIT FOP DRY for low LOSS JACK tu P 45 alt TV it AF TO i act A ct ma ND circuit Is simple to build a and nd simple to operate incorporates incorporate unique features seldom found in two control outfit as kt at P 4 P P lv twit AJ fy VAR LOW LOS jaax as OHM 0 aab AC A C C ah ratio of transformer should be from three to six to one variable condenser also must be of the proper capacity by F M RUSSELL when a radio receiver lg Is to be used in the home where it Is operated by all 1111 men members ibers of tile the family both young had and old it should possess certain features such as simplicity in operation perfectly clear and hollems hol lebs reception good receiving range loud speaking output and ft logged dial that t elaml nates tho the guesswork guess work worl 0 of tuning and makes it possible for ono one who never saw or heard lapard the set before to get any station desired desire with it by referring to the dial reading tile tho little two tube set illustrated will do all the above things in nn an edl clent manner this la Is duo due to the circuit used which la Is simple to build and simple to operate but abc atc a several unique features that give it qualities quail ties seldom found in even a two control outfit it lias has automatic or spontaneous regeneration and an primary pil mary tho the regeneration increases volume and receiving range and tho primary makes the set selective and agloni logging of the single tuning control never under any circumstances circumstance will the set howl it if the parts lire are arranged correctly and the values are as specified the secret of this la Is in tile the method of obtaining regeneration and tile the fixed condenser across the audio frequency transformer the readings of tho the variable condenser dial which IL h the only control are i permanent perm anent if a station Is once rei calved at say 20 degrees it will always be received again at that point this applies to distant as well as local stations the above results are obtained by virtue of a special tuning unit in the form of a coupler it consists of two spiderweb colla coils one of five turns and one of 45 turns tho the five turn coll coil Is ie the aper lodic primary and the other to la the combined plate and secondary coll coil it Is not difficult to build the unit spiderweb colls coils of tile the proper size can be purchased at a radio store or they can be home wound on a cord card board or wood frame this should have 11 18 13 or 18 15 spokes the winding method Is two over and two under in other words the wire to Is first wound under two spokes and then over two etc about one half pound of no 22 double silk or cotton covered wire Is necessary for this do not use enamel to construct mount tho the colls coils when finished as shown in the illustration the coupling between them may inay vary anywhere from one quarter to one half inch accords cordts ac to tho the selectivity desired lay out the sockets transformer and the rest of the apparatus as shown and wire with the direct connection method ethod in that Is make inake all connections direct from terminal to terminal nill in the shortest possible manner this may not look pretty but it will reduce the resistance and inter circuit interference and make the set more effi efficient clent after all its results we want not beauty tte the parti necessary to construct the set aside from fro the special coupler are AS m follows follow one variable var lable condenser one geared vernier dial for condenser one low ratio audio frequency transformer one fixed mica condenser two ion type sockets ono one 26 25 ohm rheostat one 2 to 5 grid leak and fixed condenser one 7 by 14 panel one single circuit jack baseboard binding posts posta screws wire etc the ratio of the lie transformer should be anywhere from three to six elx to one but not higher the set will distort it if this Is violated the variable condenser also must be of tile the proper capacity any smaller or larger will either not allow the reception of certain wave lengths or bunch the stations up on half tile the capacity variation only onu one rheostat Is used on both tubes the adjustment on either la Is critical and a 25 ohna ohm resistance resist tince will take care of them tile the connections for the fixed con condenser denAer are across the primary and secondary of tho the transformer to tile the P and F r post this must bo be placed in this athla position not across the Irl primary marv as Is customary to 70 tune set tuning tile ho set merely requires adjusting the rheostat and turning the dial the stations will come lu in sometimes without a carrier wave whistle so it Is advisable to turn the dial very slowly and listen intently to be sure bure n i station Is not missed on long distance the adjustment la Is apt to be critical A geared vernier Is essential because of this with the ordinary dial many stations would bo be passed up without the operators opera tora knowledge boston traveler |