Radio broadcast .. (1922-30)

A Winder for Small Inductances How to Build and Use a Device to Wind Efficient, Concentrated Inductances Which May be Used in Various Radio Receivers— How to Wind the Coils for the RADIO BROADCAST Six-Tube Second Harmonic Super-heterodyne BY ALLAN T. HANSCOM \AANY readers have been greatly interested in the second harmonic super* * heterodyne described in RADIO BROADCAST for November, 1924. One of the central features of that six-tube receiver is the concentrated inductances. These are wound by a special machine which is described here. The construction of this device is not especially easy and had best be assumed by those readers who are adept at using a lathe and similar tools. In addition to the method of assembling the winder, complete information is given on the number of turns and dimensions for the intermediate frequency and oscillator coils for the sixtube, second harmonic super-heterodyne. — THE EDITOR. O MANY requests have come to the writer for constructional data on the "sjnall honeycomb coils which are used in the six-tube super-heterodyne discribed in this magazine for November, 1924, that a description of the method by which these coils are made should prove interesting. In the first place, some of the more important requirements for any inductance to be used in radio work should be considered. LOW DISTRIBUTED CAPACITY p\ISTRIBUTED capacity in an inductance 1—' greatly increases the resistance of the inductance at the higher frequencies. The direct current resistance of an inductance is an inverse function of the wire size. By this we mean that the resistance of a coil of coarse wire is less than a similar coil of fine wire, but with coarse wire the distributed capacity in FIG. I A photograph of the completed coi! winder