Radio Broadcast (Nov. 1925-Apr 1926)

332 RADIO BROADCAST JANUARY, 1926 © O ® Rf-DtTECTOR COIL SUPPORTS Matenai Bras^Bakelite or wood , 2 Reautred J O ANTENNA COIL SUPPORT Material -Brass Strip '/« 1 Required ® NEUTRALIZING CONDENSER SUPPORT Matenai Brass 1 Required © FIG. The dimensions and other specifications for the angles and other hardware used to assemble the receiver are given here. In the case of the bushings, bakelite or wood will do as a substitute for brass find a harvest in the parts business far beyond their most optimistic expectations. In fact, those dealers who are following this plan, and there are a great many of them, are finding the parts business to be anything but dead. Every home constructor is actually a HOW THE SET STARTED . . . The embryo "Universal." By laying out the parts on the base-board, it was possible to experiment with changes in location of the various coil and condenser units to observe any improvement in results obtained. This system of experimental construction is to be highly recommended radio salesman in his neighborhood. If his receiver works well, and homemade receivers usually do, the builder generally proclaims from the housetops, first the wonders of his outfit and then the wonders of radio in general. Many of his auditors wouldn't give a red apple to duplicate his accomplishment, but many of them would like to be able to hear the things he hears and the rapid growth of the radio business to-day may well be credited to the home constructor. -t * SUB-BASE Materia' ^*Wood FIG. 3 The baseboard layout. Especial care should be exercised in cutting out the section to be removed so as to prevent splitting the wood. The use of this type of baseboard insures easy assembly and wiring No 18 Hole THE PROBLEM ALL of the foregoing was brought to mind by a moment's consideration of the problem at hand and our reasons for dealing with the subject of the universal receiver. First of all it was necessary for us to determine on a particular circuit. It is almost impossible to think of circuits at all without thinking of all the dynes and whosits and so forth which were given so much free the newspapers a few short months ago. Most of them have met a natural death. There remain but a few tried and true circuits, so the matter of selecting the proper one for our individual use, is not such a difficult job, eyen for the uninitiated. There are many we could attack and use to good advantage, but when all the smoke has cleared away and the shouting is all over and we get back to a peace time basis, there is but one real type of circuit which may be called universal and that is the combination of one stage of tuned, neutralized radio frequency amplification, a regenerative detector and some kind of audio-frequency amplifier which will produce good quality. To explain the kind of a circuit we are describing, each time we have some variation of this circuit to contend with is indeed embarrassing and the name "Universal" is about as near the correct characterization as we have been able to find. All No.18 Holes 1 -e-V-e s&-i%l --H space in FIG. 5A This is the layout for the binding post terminal strip. Bakelite, hard rubber, or formica XV inch thick is satisfactory for use here No.18 Hole SUB-BASE SUPPORTS Material: %"x Strip Brass. 2 Required FIG. 4 Two brackets, made as shown here, support the baseboard assembly. Approximately 32 inches °f h x A"'ncrl strip brass are required to make the two brackets See Fig.3 Bracket v Bracket See Fig.4 See Flg.5A ' FIG. 4A The baseboard is mounted on the brackets and panel in the manner shown above. Two brackets tor the terminal strip are ruquired. The vertical part is ii inches long and the hole for the strip is located J of an inch from the bottom -r — \ 9' 5k H ; Jj" Hole^ .7 k V16 Hole 5 V H Hole Vie Holes -$ ©;.'/„ Hole - 3*" .„3V...>U '/» Hole — 7h" =_ h<----3% 1£ FIG. 5 The panel layout. Only center holes are shown so as to enable the builder to use parts that he may have on hand which differ in make from those recommended. In any case, before these center holes are drilled it is well to spot off the other mounting holes