Show N art r I 1 a far I 1 it dip ili TIC 5 to koa 05 41 V as AA bo 38 0 1 aj at chilt introduces a new IF e I 1 of select vity into the multi au it plex C will interest all radio fans dy by LEON W BISHOP 1 I I 1 hii i i ahli in th the 1 1 1 I 1 I 1 I 1 X I 1 till if I 1 lit 14 ml ok k n of 11 II PI ifill it 1 li 11 1111 11 ni mi it 1 I limit if 11 II 1 11 lut 1 1 I 1 i 1 11 ll r egl tr tit 11 4 lia it I 1 if I 1 li I 1 if lot s i I 1 ir lr i II 11 it it tr stiffs 1 li a ll 11 1 I 1 f H 11 ll 1 lilt I 1 1 i i I 1 I 1 i x li 11 1 1 it 11 it 1 I 14 I 1 iiii fil r II 11 A I 1 III nojir I 1 tr tit the 1 1 i 0 II 11 I 1 I 1 r i nr urt it f ur tir indi ir 11 II ird ait t ll 11 i I 1 HI so if 11 ht 1 HH ur or i 4 i 1 1 in fit imi t 1 I t la 11 lo 1 M I r on ion thip little lal ait tl IN loo lilt it with ith 0 turns of no 1 U i 1 r J 2 1 tit ciulli ua it ct ilion cwi v red arc ire k I 1 ip ili IN 1 tuhan 1 nt tit IN tit turn t f ato i ll 11 M PI 11 II 1 1114 tl iltis I 1 of ful 4 nt ion I 1 nio ni o in lit rounded round td starting froni front lilt for dortith fill fill turns hie tile it tian ft imn ht 1 h I III lieve five live tup ill Is S S ll 11 connected to tho lilt this saip the si mutt littin ni it IR 1 pos 1 to onnet in three six nine t lip rind leftien in the antenna circuit tills under li if a 1 l interference enable oil to tune line out amr loral local stations and still prelve from distant points connecting the taps in connecting connect liiK tile lie tops tile wire may be cut and holes punched in the tube and the wires mires dramn through these fly punching holes in tl e tube anti dram ing the kirea I 1 res tit chri r ailt h yon you mill III make UK the winding minli inner firmer and eliminate the tile ut of shellac or i r fitly other kind of ROO goo the arlo I 1 mar le be of an oil stan make on tile mark t alie crid grid con condenser dener ati uld he of the mira tile nod have a of nirl tile grid 1 leik le ik should be re arni chrite ahr to nine meg mpg oil imis ins a nine inego ino Kohin lim grid leak heing being us asid d for local reception do not put on larl ar ahle lable grid leaks it li itt much better to huc hiie a spare rid grid leak say for instance a chrt time e me colim an I 1 a nine anti snap these in at wf ft tip v triable con convener lener VC IC should be mf off preferably of ine the 23 21 plate type tylle of couden sir here I 1 might say suy series parallel switch its uses in receiver the series parallel switch ellmin eliminates ateR the nece of changing of wires lur dur ing it test of a circuit it comes conies in very haudy for a quirk quick change mer from one circuit to another of the head phones another use for the ti herlea parallel switch Is found when hen it 1 lot used in connection with alth a batter char charsie tr and the for the set men hen the si switch flitch Is in one pogi position tion the battery 14 1 4 thrown to the charger circuit and when in the reverse direction the battery la Is connected to the set the method honn shon in the accompany ing diagram Is used in connection with the honeycomb coll coil circuit it Is used in the primary part of the circuit to throw the condenser across the coll coil or in series with it the honeycomb coll coil circuit requires the u of euch such a snitch 8 itch in order to chance change from medium short waves aves to C 0 to jet I 1 showing how series parallel switch may be employed longer waves moves the witching switching arrange moot meat allow allows the use of a certain coll coil for a wide mide wate wave lenth lenith range an example of the series parallel switch in honeycomb coll coil net let Is elun a ae fo dollois llois suppose an L 25 coll coil ulas being used in the primary to tune to amateur wares below belo meters und and titre alx re vias an immediate deed to go up on the higher wave length of the broud casters to bear particular pro cram train ordinarily for amateur nork ork the condenser would be in series nith mith the coll coil but the change mould necess necessitate ite 1 e the thos condenser being put across the co coll it the condenser in shunt with the coll coil boosts the move lenth lengh up without put ting in lu a dew new coll coil this Is a much easier method than hunting around for another primary col coil and taking time to plug it into the circuit after removing the first col coil from its primary plug not atone alone may this method be used in a honeycomb coll coil set sel but may be used ased with ith any primary it Is sometimes desirable to harin n the tuning of a single circuit set this Is accomplished by taking the series condenser out of the circuit and con celaa it across the primary tap a li I 1 ai tit lilt I 1 if I 1 11 ax lifar 1 0 k mt ill nulla li lim imp u il it I 1 1 ie in iotti NI r i III tills I 1 alln tit I 1 aln I 1 talt I 1 tn lot to 10 ahing an oil I 1 fill I 1 it I 1 in tile gatino na side if tic tie ti I 1 wiry I 1 II 11 I 1 I 1 b ir rt pit tube for mot in 1 till thin cir lit fit I 1 tilt lit I 1 lo ell tap wit I 1 II 11 and 2 na t J hi tilt f A iiii lilt if lip asil asti I 1 clr ili it built r should I 1 li it from front li to 4 1 11 x it ili H riling piling up in tin I 1 lip tilt P hitron lilt hi trot t ilic I 1 lit b I 1 asa ea oliou lil be air ilif nial I 1 nn on III creft ml ral 1 b if f tin tilt ml fill a it tyl fyie p connecting the circuit in up hi the lault it lit lest ti it lune hop the tiri able in ion aler on tie left hand molt 1 of if tile tip i ind ini tic tie arlon vur on ii tin tilt ilehr lilli j tittle of the the switch tops 1418 I 1 low to in tin the ct nit r of lie tile dunel tt tilt hitt stitt maa I 1 ie e in the cen r I 1 lili on the tile I 1 all anol A 7 by 0 should I 1 e alaj ii I 1 Is 18 of little arll but tie r I 1 hinry plates of the arin ble mn dinser C must he be to th ari bruni un I 1 it must be that the iad from the grid on the to the grid leak and condonier condon ser should not be more than one inch in length UP 1 lie hodi capacity effect of this lead I 1 Is in tilt most critical of the set rhe atit i it lead Is the one froin from the pinte to ti the virlor neter leils blound be kei t ag as sin shi rt as not possible io af A batter 1 tit l ili hould be fatir dr ln cells in the cit re of the tin I 1 lot tubes tilt nn nit I 1 three dry celle cells for the L IM brind ind CO tube although the switch joints eints tire only three turns fit tit 3 make a mst fust in selective tle tuning timing in no case eap can there be more than 15 I 1 turns in ili the an circuit thus the chance of radiation Is almost almott nil loll again I 1 wish mish to wnm the use of shellac on the tuning coil TC I 1 this circuit may be amplified in the tilt sime manner as the multi circuit the point gained in cir cult Is find the tile practical elimination of the fir cir i cult will be immediately noted fr its I 1 wonderful nond vond erful quality reproduction vew new lork ork sun switch and the lower end of the coll coil winding m I 1 rie the form of itch shown in the nc tie comparing comp anIng 1 drawing may I 1 ie P purchased in any radio store as it Is of the stand ird type be sure surp to make rood good cn con on the back and keep the switch so that it does not out of adjustment the critney crit net joints may be mounted on the panel as veil melt as its the re rest st of the tile an switch itch the switch points should he kept clean f to insure better contact elili the switch arms the market also affords a series parallel switch all mounted so that only one ove hole bole la Is cessar nc in the for the center shaft such a mitch 8 itch eliminates the necessity of drilling eight holes in the panel penel and N decoln o 0 mended where space on the panel III 1 at a premium chicago dally daily journal hints for constructing tuned R F amplifier in constructing tuned radio fre re quency amplifiers separate the tuning colls coils to cut doa down n the magnetic and capacity coupling between them uee use loose coupling between tie fie mary and secondary colls coils of tuned transformers separate the variable condensers used to tune the lo 10 arious circuits bj by at least fire indies inches experiment with the coupling between the primary and secondary colls coils of the dudlo frequency transformer to find the separation glies the loudest signal strength with jtb out making the tube oscila oscillate a te use lamp cord twisted for Binni ent leads and thereby avoid large citified loops keep all battery leads away frol tit the tunina apparatus und and by doing these things it will be possible to build a radio adlo frequency amplifier that will not oscillate when botu both rid and plate circuits ire in reso resonant nanc pointers about makeup of dry cell batteries A dry cell battery consists of a I line in container oiled filled with chemicals in the center of which Is a braes brass capped car bon rod the zinc can Is the lie pole or el electrode act rode a and nd the center in carbon abon Is the pos iffie pole or electrode th thil voltage of a dry cell Is about U 15 when mitten it Is not in circuit open circuit voltage and it Is lomei when it Is in circuit closed circuit voltage depending on the cell resistance of th circuit to which it U Is in |