Radio broadcast .. (1922-30)

USING HONEYCOMBS IN THE KNOCK-OUT REFLEX THE use of different forms of inductances in the RADIO BROADCAST Knock-Out Reflex circuit, such as the straight winding and the spiderweb heretofore described in this department, has suggested to many of our readers and to the RADIO BROADCAST laboratory staff, the possibility of using the honeycomb inductance. Our experiments have shown that the experimenter and builder will encounter little difficulty in adopting this form of inductance as the main winding in the reflex circuit. In reference to the diagram shown on page 327 of the February RADIO BROADCAST, our readers who have been following up the development of this circuit (and they are many) will recall the following specifications for Ti and T2. Using a two and a half inch tube, the secondaries were first wound, sixty turns being used for each transformer. The primaries consisted of fifteen turns for Ti and thirty-five turns for T2, wound over the secondaries, with an insulating layer of paper between. The simplest way of substituting the honeycomb coils, is using them as the secondaries, winding the primaries over them as usual. Figs, i and 2 show a set built up in this manner. Honeycomb or duo-lateral coils, No. 75 were used as the basic inductances. Twenty-five turns of wire were removed from each coil, leaving 50 turns (in the case of the DL, the equivalent). The inductance per turn of the honeycomb coil being greater than that of the layer type inductance, the result is about equal to the usual sixty turns. An eighteen-inch strip of cardboard is wound over each secondary FIG. I Front view of reflex and two step, using honeycomb inductances