Show h 1 Ward rolp editor of TOP G 0 copen ar BOTTOM 1111 0 buted in three circuit regenerative tuned plate set OA SET AN TOP OPEN 0 G R ON bomm dill 0 RP kyll W MP T OM VAR COND 23 I 1 vitt z GROUND used as a wave trap in grouted wire and gy WILLIAM J SCHNELL et months of experimental work hi tire found that what has been recited ed is u the standard type of vario varlo apler Is I 1 lacking in the one element A essential to its success the of energy from the antenna ailt I 1 to the input of the radio re alii aset kt with a minimum of loss loes an I 1 11 fill rely y new design embodied in a coupler known as a selecta er his has now been devised which iles mes this serious deficiency in oil old other defects A ilat have a serious bearing on rete ef till efficiency clency are also eliminated tr fik couplers oily lers generally are designed so do it the hi primary unit Is of such an cata ca constant that together with antenna constant with which it maloyed the desired frequency ii d h f covered the primary unit Is y tapped so variation in the at of the primary circuit can be 1 to permit of obtaining resonance uj UI particular incident frequency it was considered that A i a coupling resulted in the mari maxi not received energy in th the e antenna am ft the secondary circuit was tle tuned for the same purpose MCI ni in also generally believed that a A 04 i anna um of energy could be trans ima mu fl between these two circuits cir culta with irl of loss under the condl I 1 lie 0 lent dent miam da mentally this should be con ried d a d is 13 the basis ot of the laws of tin ormer action these conditions clift at audio frequencies but it ro onu tate different when this trans I 1 ay tr kation is observed at radio tre fre WK baft aide this applies particularly to me I 1 coupling of the antenna to the d of radio frequency am fi L when used in this manner I 1 el tot lot desirable that the coupling ft close nor that the antenna be ad ua to resonance far better re buol 3 till be obtained it if both these or atals are actually reversed 0 t loose coupling and no attempt I 1 1 dito to secure resonance in the an in item there are good reasons I 1 be etli somewhat radical departure 3 accepted principles n keep resistance low wit 0 1 I Kr Nd istance stance should be kept at the lb possible value in the input ciru some of these ench such as con it dot d resistance resistance due to afat ted capacity in winding form isicc ine due to dielectric absorption d 4 tre ire readily handled that their atlon to Is not go so difficult but when input circuit Is coupled to the an in aa A weib stent we find un an addItion 1081 all rea a a lamely one of energy ab JI S when two circuits are con W 80 0 o that one Is I 1 transferring en to the other the primary circuit r j to reabsorb energy from the seo see 17 this amount amounts to a reduction eller received in the second cir of btty the het bet result la Is an apparent w 1 10 l hi IA the secondary condary ic resistance aft r we fe find that more nearly ole the a B circuit cult approaches approach ea resonance le the secondary circuit the greater L arfer et of energy h hence ence the S er 1 tace from this effect effect 13 s more pronounced the o 0 i tt tahe the PrIll inary alry te Is in resonance to condary and the closer the arf it between these circuits I 1 ll 11 I 1 once e becomes evident that if im to r nt qt down 10 the resistance t secondary circell it we must avoid ti biall codr our antenna to the input s and likewise keep the coupling W mid capacitive by the way IM tell the two circuits at a mini 1 i it it 1 does not follow that we can extreme tx looseness ot of coupling y too far off resonance resa nance in our J 1 masi 1 as thie this would lead to IWO 0 9 a ef of in our input cir dr n sa olter it haj has been deter that att it ai k certain a resonate A aa point la Is reached and likewise a certain looseness of coupling they will result in a maximum transfer of energy how to be determined experimentally his this may be determined as follows set up a driver circuit a CL W arranged so that it can be variably coupled to an absorbing circuit qt provide thia absorbing circuit with a current indicating device eo so that as the coupling between these circuits circuit Is varied the reading of the indicator may be plotted against the coefficient of lie the coupling of the two circuits aa As the coupling Is reduced the indicator will aill remain practicably practically constant until a certain point after which it will show a very rapid in crease in value As the coupling la Is further decreased the indicator will rapidly drop to zero evidencing that the energy transferred Is nil at this point the point at which the andl cator shows the rapid drop should 1 be our most efficient coupling coefficient this point must mean where our absorbing circuit resistance Is low it aed used in a circuit this point should give the ma mum of signal strength and select ty hew new york sun things about I 1 aches amateurs S know there are two kind of panch one with a long slender ani out sharp point and the other with a blunt point if any such thing exists the slender one Is 1 useful when ahen you mark the centers for holes on the panel punch ing through the drilling template which you got balth ft ath the box of part parts or which you drew ri yourself this aunt PON L useful Pu richeL makes a needlelike mark on the panel but it Is not enough to start the drill through on the straight and narrow take the sat flat nosed punch next ind go over the job making a it wide depression wh which ich the drill will fit into easily if the blunt one Is 1 used first it Is likely to slip off center on account of inequalities in the paper or uneven contact with the panel ma aerial new lork telegram parts needed to make your B battery switch the illustration shows snows a switch for a variable 13 battery the parts necessary to male tills device are ills on I 1 switch arm and from five fire to sem switch points mount fount these on a e small wood panel 3 inches squam run a it wire ire from each switch point to each plus terminal on th the e D bat tery run wire from the center of the to sar to SAT regulates Re gulit plate voltage set also run a wire witch switch arm to the froni from the minus elde side of the battery to the usual manner mariner both in the beet et will enable the user this little evitch witch plate voltage without regulate the to ot of chan the trouble be having ving to like take ammu in case wires lume rou ing of 43 used the 08 minus ride side 0 flera tiers are ire connected connect td volt battery li if alo also or 34 of the tb twite um to the tho itu center ter die divert |