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Show SfRADIO TUNING CIRCUITS HELP REDUCE STATIC !j ., !! ' Be pu ' ,. i;.i.:m. " Cjwbifh they have vari- lajMm"!!-.'' Jumped to the j ""r ; "ling h i gone 1m M'l- radio-; ' W&l nam sourc of dhnurl.- , in Wireless communication. Engineers En-gineers for mam- years have diligently diligent-ly npplied themselves in an effort to discover some way of eliminating the effects of static. No method has yet been discovered which will cut. rely eliminate static, el- I though many methods have been put 1 forth for minimizing its effect. When several OJ tho h mi devices are used -ii lult&nooualy In connection with any j one receiver, it Is possible to get as ' high as cm per cent improvement in that set. The measures necessary to securo this imprpyornent, ai c. ot niUuro en. tlrely unsulted to application on tho nome radiophone s'-t because they are bulky and expensive. SINGIjI ( R4 t : 1 si 1 The first means discovered for the reduction of static Interference was the tuning" of the receiver circuits. The next step nras one where this tuning tun-ing was curried still further a second Y ? Shigle Circuit Receiver tuning f irouit was added to the receiver receiv-er ini "coupled." weakly to the tuned antenna circuit. A great many radio receivers in uso today arc- ol the incle circuit" tpe. ,Bui considerably greater fredoid 1 static disturbances Is to be had by the use of a "two-clrcult" receiver. I Wt)-( RCU1T SET l"!n IwocjfrCult receivers of the crys-I crys-I tal type are usually composed of an X it n i "irr f Two- ireuit Receiver. "inductive coupler" (loose coupler) together to-gether with varlablo tuning condensers condens-ers used In both antenna nnd the sec-ond sec-ond circuit (closed circuit.! L'nfortunately, tlie receivers which have been exploited most during thf last few months have been single-circuit receivers. As the radio public becomes educated, it will demand recovers re-covers of the higher grads They do not cost a great deal more. THREE-C IRCl IT SFT The use of "regeneration" in the circuits of a acuuni tube receiver (' regenerative receiver''), where tho receiver is built around the coupled circuits with an outdoor antenna will m y 4 LjiJjjll o 1 n . -, Ireuit ReeeivcT give the greatest freedom from ln-terference ln-terference now possible for the radio fan. Such sets are known as three-circuit three-circuit receivers." To go beyond this necessitates the use .f recelvei In connection with a "loop" oi- "toil" antenna. Tho coll antenna consists of a few turns of wire on a frame three or foul i"e'i square, the potentials developed devel-oped in il by the advancing waves, are. of course, very much smaller 1 about 1-L'Oo part) of those developed in the outdoor antenna Greater amplification amplifica-tion more vacuum tubes, batteries, etc. are necessary where such an antenna an-tenna is used and this means more expense. |