40 now A pei 7 J ae A A the wiring diagram for or five tube radio frequency Re receiver celver by EDWARD edwand SPIEGLER in new york herald for a dependable trustworthy radio broadcast receiver one that will work consistently night in and night out without fuss or bother the writer believes it Is difficult to find one more desirable than a straight five tube three dial tuned radio frequency set constructed with efficient condensers and tuning cotla coils and equipped with standard accessories the sensitiveness selectivity and volume of an outfit of this type can be practically guaranteed in advance and tho the builder can be assured that he Is not spending his money on some ones notion of a freakishly different indifferent receiver of undetermined worth when he has finished the wiring and connected the batteries bat torlea he will hear broadcasting and hear it well the writer recently completed such a receiver incorporating in it the acceptable innovation of a few new tuning inductances and enjoyed an instant satisfaction from it that was was unusual ile he had previously made a number of popularly exploited radio frequency sets aeta of different design find and had spent whole evenings of patient adjustment on each in an effort to obtain good results this orthodox unpretentious outfit boasting noth ing ine more radical than some straight line frequency condensers conden sera and some different IL F colls coils produced such buch immediate results resul tsin in the form of many and loud stations that lie he thinks people who want foolproof fool proof receivers should be told about it parts required the average constructor will have no difficulty in assembling the set with the aid of ordinary hand tools the parts required are a panel 7 by 24 inches of any good insulating ma aerial a half inch thick wood baseboard of the same dimensions three gen win lemnus colls coils three mad straight line frequency condensers three dials to fit same one sir and one thirty ahin rheostat orie ono double and one single circuit telephone jack five stan standard V ard tube sockets grid condenser arid r leak ti two 9 audio fre ke quency transformers a one battery switch ono one binding post strip and the usual bulbar and other incidentals the set la Is most conveniently assembled in two units the panel and the baseboard the sockets for the R P tubes occupy the alie space between the variable condensers and a little to the rear of them the detector socket Is up tip in th the e extreme upper right corner of the baseboard and la Is followed by the A IF transformers and tubes winding along the back edge of the board the second A F tube Is in the upper left section its P post going conveniently to the telephone jack in the lower left corner of the panel similarly the right hand jack connects to the adjacent detector socket this shaped iny out keeps all the connections very short and in their logical order about 90 per cent of the wiring involved in the construction of this athla receiver can and should be done on the baseboard instruments before the tha pari panel elAs Is screwed inta position the constructor is 18 advised against assembling sem bling the parts first fira Cand and wiring afterward as the presence of the protruding variable condensers will make the installation of many of the wires exceedingly difficult no binding posts are provided for the 0 battery as this unit Is most easily connected by means 0 ot short sh rt lengths of flexible cord the other battery connections are standard and gre are easily followed the wiring the wiring of the R F and A P V stages Is more or less orthodox in nature the three variable condensers are connected directly across the respective spec tive of the leonls colls coils with stationary plates going to the ards of the tubes and rotary plates to the filament circuit the feature of this receiver outside of f its general effectiveness la Is the type of radio frequency tuning units employed each one consists of a 18 15 turn primary and a turn secondary the wire being wound according to the principle this form confines the electromagnetic field and neutralizes centralizes the tendency toward osell I 1 lation the extraordinary leng length th of the curve reduces the resistance si stance otherwise encountered d in small diameter coils the wire used Is no 26 enameled high turn to turn tum capacity being avoided by a system of spaced winding over all a coll coil Is just tareo inches long and two and three quarters across the loops the small diameter of the latter Is one inch an ingenious experimenter can readily rig up a jig ninde made of two short curtain pole sept sections ions on ei end a of a board and produce de dc colls 1 I 1 the dl 41 prisons 1 long vh inlall h th thi magne magnetic tle j A flux of each aft don of these collit assume by virtue of the peculiar liar winding scheme are such that the colts colla as units have completely confined magnetic fields this property precludes the necessity of mounting the colla coils at particular tingles angles in a receiver in order to prevent coupling the absence of interaction also gives each colt coll a fixed and definite inductance value the lost last mentioned fact la Is responsible for a very desirable effect namely the almost exact ordination coordination co of the three variable vcr lable condenser readings from meters right up to different aerial lengths seem to have little influence on the first condenser reading the variation at three different locations being not more than one point on a scale to select several DX stations of some sixty five alve tuned in during two nights of listening the dial readings were 71 70 for miami beach fla 00 69 6 09 60 for WOY schenectady arid 89 89 89 for WIP phila it Is actually possible to hear a station on each dial setting because of the wave channel allocations and of the straight line frequency characteristic leof of the receiver