Show edited by 0 douglas bailor of radio ludlo N 7 10 rD V A a M ICA COND oo 00 VAR CON no IA 1 N PI ATES A selective portable there Is nn an unlimited held field tor for pod single tubo tube portable set circuits any regenerative type of circuit will vill give good volume on a single tube the main problem Is to use a type of tuning unit that will permit maximum selectivity in the hookup hook book up illustrated a varlo coupler Is used lit in conjunction with a u variable condenser for the tuning unit the rotor supplies the teed feed back of the plate circuit the circuit Is not primarily intended for loop aerial reception although one end can be connected to the antenna post the other adrid left open and a regular ground connection used avien so connected some very good rc results ve are possible it a straight wire alls je cellai Is used lisea a length of 60 50 foot feet can bo be thrown over a convenient tree of course this will not give the best results it if time Is available the wire should bo be suspended between insulators A copper rod driven into nto moist round ground will give sufficient clent ground connection cotlon tion this can be improved by soaking the ground around the rod with salt water the tuning timing condenser should have a capacity of microfarad to cover tho the increased wave length range the rotating plates should ho be connected to the ground side A blocking condenser of ml mi crofard capacity lg Is inserted in the rotor circuit so as to avoid short circuiting the batteries through the plate circuit the grid leak can bo be of the variable typo type but this Is left to the option of tho the maker the tube Is a detector although hard tubes such as the can bo be substituted in such a caso case it may bo be advisable to increase the plate batte battery ry voltage A cushion mounting for the tube socket Is recommended as a portable set gets considerable knocking around that doe doa s not help arese prese the tube filament the rheostat resistance will depend on the type of tube used if a or Is used a 20 to 25 ohm rheostat Is required otherwise tho the standard C 1 ohm rheostat Is clent |