H. E. Dill

The writer, not long ago, when experimenting with devices to gather in the waves at the receiving end of a wireless station, utilized the receiver and transmitter illustrated in the following diagrams. A description is here given, not so much to exploit results accomplished, as to give to the hundreds of Amateur Work readers now studying along the same lines the value of a co-worker's efforts. The receiver, while not perfectly satisfactory at all times, has proved more sensitive than any coherer it has been the writer's pleasure to make, but needs further development before it will be susceptible to systematic tuning.

In the study of condensers we find that the value of the unit of capacity is derived from the relations between the charging current and the E. M. F. produced by it at the terminals of the condenser. And we find the time element a factor in computing condenser capacity, inasmuch as the current strength has to be multiplied by the duration of the charge in seconds.

It is to be presumed that a receiving condenser to operate successfully as a collector of disperser waves must be constructed to operate in harmony with the radiating waves at the dispersing end. Therefore, we must first note the character of the originating high potential discharge, which is of high frequency from the one coil and low from the second. The primary voltage is 20 and amperage 10 in each case. The interruptions in coil A are always exactly proportioned to the interruptions in coil B. This is brought about by mechanical means.

The capacity across the secondary gap in each coil is .0005 M. F. With this duplex sending device a distinctive wave is emitted which, varying in prearranged frequency and differing in penetrative character from any wave that may be dispersed from one coil, makes it a powerful wave to send and a difficult wave to intercept.

At the receiving end two wires also are erected as in Fig. 2. The receiving condensers consist of twin No. 40 covered magnet wire coiled on a glass tube and the entire device immersed in kerosene oil. The receiver itself is connected in series with the condensers and consists of platinum wire points in a vacuum tube about the size of common thermometer tubing. Bridged in parallel with the receiver, is a battery of 50 volts and 8 amperes and on the reception of the wave at the condensers, a discharge (invisible) takes place at the platinum points, and a restricted portion of the heavy battery current finds its way across the gap, thus completing a circuit through the 5,000 ohm relay which, in turn, controlls a recording device, as in other systems.

The writer finds that a wave from the Slaby-Ar-co-Braun equipment, such as is in use at U. S. naval stations, will enter on either or both receiving wires and pass to earth without operating the receiving circuit, for reasons plainly evident in the diagram. But the two distinct waves that blend in their course from the duplex coils to the receiving station, seek a natural course down the wires arranged for each wave when they reach the receiving arials. And not until the same conditions of syntonism prevails at the receiver as at the transmitter is the relay supposed to respond.