Show diagram of five tube one control radio frequency set which positive control of 0 by JAMES E CARTER in the new york herald tribune ahe radio buying public has reached certain definite conclusions about what makes up a good radio receiver these conclusions in practical form are embodied in most really successful manufactured sets of today some re behers have greater perfection than others some are of better design and construction A few aie outstanding in A good set first of all whether it be homemade or factory built must be of correct design the home con who is contemplating tho building of a receiving set Is natural ly desirous of obtaining the utmost in the way of performance and Is keenly alert to improvements in tho successful manufactured set the first point of importance 0 o the home set builder will be the type of circuit to use it Is needless to say that the day of the regenerative tickler feedback type of receiver without radio frequency amplification before the detector Is over there remains the straight radio frequency circuit with positive con strolled trolled oscillation which Is probably the easiest all around highly efficient circuit to construct volume and distance for the set builder who Is situated fifty or more miles from a broadcast station two stages of tuned radio fre quency amplification followed by a detector and two or three stages of audio amplification will ghe ample satisfaction in the way of alume and distance where the user Is located within 60 miles of a strong broad casting station three stages of tuned radio frequency amplification Is feces eary to work distant stations as near as 20 kilocycles kilo cycles either aboe or below the near by station in the accompanying diagram the five tube radio receiver to be described in this article 13 shown this set employs two stages of transformer coupled tuned radio frequency fie quency amell fi cation a non regenerate e detector and two stages of transformer coupled audio frequency amplification an examination of this diagram will show that there Is nothing unusual in the wiring of the circuit the chief point of interest being the way in which one control tuning is accomplished A triple condenser ton denser Is used to tune the secondary colls of the three radio frequency transformers all of which are identical in construction and a small adjustable fixed compensating is connected in shunt with each of the three units of the con denser to compensate tor the varla alon in the capacity of the wiring of each of the circuits also a variable antenna compensating condenser Is connected in shunt with the unit of the condenser tuning the secondary of the antenna coupler this has been found necessary to make possible etal dent operation with any type of an tenna another feature which makes the set more flexible Is the small fixed condenser which may be placed in series with the antenna when this condenser la in use the receiver Is more selective and may be operated from a large antenna without expert interference the parta needed the following Is a list of apparatus actually employed in the construction of this receiver one three kane condenser each section mad three radio frequency transformers matched for use with the condenser lerlee or homemade home made two Thor ardson audio frequency transformers one compensating condenser BO one BOO Centra lab variable resistance si stance one Centra lab modulator optional five benjamin sockets two fixed bondena condena con dena ars on 01 mad fixed condenser two 1 mad fixed condenser one 5 meg durham erld leak one 6 ohm rheostat one carter battery twitch eleven eby posts one panel inches one panel 16 inches two panels inches one baseboard inches the method employed to control the volume of this receiver eliminates the necessity of connecting jacks in the output of each stage of on A ohm variable resistance Is connected in series with ohp plate supply of the two radio fre quency amplifier tubes and bs ad this resistance the of the receiver be may increased or as desired by lulng this method to control alume any desired amount of sound ropy be obtained without introducing distortion also ails method Is superior to the set as it does not reduce the de aree of selectivity in addition to tills ht 01 abo 18 P with a m modula ra device to con arol the output of an audio anell fler this instrument Is not shown in f the diagram as it la not considered necessary when the sensitivity costorf 1 Is employed for those who wish J T use a modulator however it may be c explained that it consists of a lilot I 1 resistance potentiometer connected j across the secondary of the first audio i frequency transformer with the j connected to the grid of the tube I 1 the triple condenser B As may be seen the whole set li a built around the triple condemi con demy 1 which Is of the straight line frequency t die cast type this entire lau 1 in an aluminum frame uj inches long and 9 inches deep which J serves as a panel and colt mounting 1 studs projecting from the rear of the casting sene to hold the colls in their proper position and the two afcan I 1 by 3 inch panels supporting tha sot r ets tor the radio frequency tubes araj fastened to the base of tha casting with machine screws 1 the amplifying apparatus Is ed on the 10 by 41 inch panel mem in the list of parts the loca S alon of the panel and ane arrange v ment of the apparatus is clearly nl shown in the drawing after the ap has been mounted and wired on this panel the panel be f fastened to the baseboard with ing brackets ta the tuned radio frequency tram c formers used in this set should all t apfl purchased with the condensers or fe home made it homemade home made the sec l id andary winding should have 65 turns pe of no 26 double cotton covered wire ea wound on a three inch diameter hubei i the primary winding consists ct blue toil turns of the same size wire on i n inch diameter tube Q the angle to which the colls ire cd mounted in the set should also t lie noted as this Is the customary w alon to minimize electromagnetic 5 coupling and Is approximately 57 dar id drogs grogs U ft hen wiring radio frequency clr ft cults careful attention should be gives to the location of the tubes in order to keep the grid and plate wires u yi short as possible ml the next job t after the receiver has been assent ili bled and wired as described in w article the next job Is to balance tt three tuned circuits and the circuit to the same inductance biltl lv Is necessary to make it possible te the triple condenser to tune the thaw ul circuits to the same wave lestri pa simultaneously to balance the L clver the antenna ground batteria and loud speaker must be connects to the set and a powerful local bit alon tuned in it it Is found impossible to tune in a station with t loud speaker head phones connected in its place and the W adjusted until something Is hea after the local station has 13 tuned to maximum volume with ast 1st master control of the triple condense the antenna compensating bondena condena con dena should be tuned to gala a tua crease in signal strength the caf problem Is to determine whether u radio frequency circuits T the master control w be turned back and forth throw w few degrees on the dial and u found that there are two poto 1 att the dial where the signals a it Is indicative of the tact that W W radio frequency transformers are tuned to exactly the ma w length if this Is found to be ane the dial should be tuned to one 01 points of maximum volume an small compensating cs 0 rear of the condenser maximum volume Is this has been done the test ia p w w ascribed scribed should be repeated sure that only one peak remains |