Page:US patent 851336.pdf/3

 largement of the capacity of the condenser 12, whereby finally a very sharp tuning of the transmitter to the length of the waves of the distant transmitter is obtained. Then the detector is cut off from the transmitter by means of the switch 7 and the circuit is again closed over the wire 11$x$ and the switch 13 is opened. The transmitter is now ready for work, so that signals of the just determined length of waves may be immediately sent.

Instead of breaking the transmitter circuit by the use of a switch 7 at one place and switching on the detector into this place, the switching of the detector into the transmitter may be operated without such breaking of the transmitter circuit, in the manner shown in Fig. 2, the detector being placed in parallel to the sparking device by the intermediary of the witch 14. During the transmission of signals the switch 14 is in the position of repose shown.

If in tuning the transmitter, the capacity of the condenser 12 has not become large enough to be able to be neglected relative to the capacity of the aerial conductor and that of the condenser 4, a small alteration of the tuning value takes place when the cell and the condenser 12 are switched off, in the direction of an enlargement of the length of the waves of the transmitter. In order to avoid this it is preferable to employ the connections shown in Fig. 3. In this arrangement of the electrolytic cell 8 with a previously inserted condenser 15, is switched on by means of the switch 16 in parallel to the variable condenser 4 lying in the transmitter circuit. The condenser 15 must in this case be as small as possible and, in the tuning of the aerial wire, the condenser 4 must not be altered, or at least only gradually altered, whilst the fine tuning must take place by the alteration of the self-induction 5. After the tuning has taken place it is then only necessary to switch off the cell and the condenser 15 by means of the switch 16 in order to make the transmitter ready for dispatching messages. The arrangement shown in is more particularly employed when the condenser 4 lying in the aerial conductor is a comparatively large one, whilst the arrangement shown in  is only employed when the condenser 4 is comparatively small one.

In using a transmitter which is fed from a closed exciter circuit, a similar arrangement maybe adopted as was described with reference to Figs. and but the circumstances are not so simple as in those cases. In fact it does not suffice here only to tune the open transmitter circuit alone but also the closed exciting circuit 17, 18, 19, must be tuned to the length of the waves radiated from the transmitter. This is done in the simplest way by the open transmitter being first tuned in the manner described in connection with, and then the closed oscillation circuit altered by variations of the self-induction 17, until a current meter inserted in the transmitter, for instance, a hot wire instrument 20, indicates a maximum oscillation. The desired coupling between exciting and transmitting circuits is established by altering the coils common to both circuits of the self-induction coils common to both circuits of the self-induction coil 17. By this means the number of inherent oscillations of the aerial conductor is indeed somewhat altered but this alteration of the self-induction of the aerial conductor is so small by reason of the self-induction which is distributed in the aerial conductor being so small that it may be practically disregarded.

During the tuning of the transmitter circuit and also during the transmission, it suffices to short circuit the current meter 20 by means of the switch 21.

What I claim as my invention and desire to secure by Letters Patent of the United States is:

1. In wireless telegraph apparatus, means for tuning a transmitter to a distant sending station, said means comprising the combination of an open oscillation circuit having an aerial with an earth or equivalent connection, means in said circuit for varying its inherent period, a detector responding to current intensities, means for connecting and disconnecting said detector in said circuit, and means whereby electrical oscillations may be produced in said circuit.

2. In wireless telegraph apparatus, means for tuning a transmitter to a distant sending station, said means comprising the combination of the transmitter, means for varying the inherent periods of the transmitter, a detector responsive to current intensities means for connecting and disconnecting said detector with the transmitter and its period-varying means, and means whereby electrical oscillations may be produced in the transmitter.

3. In wireless telegraph apparatus, means for tuning a transmitter to a distant sending station, said means comprising the combination of the transmitter, means for tuning the transmitter,  a detector responsive to current intensities, means for connecting and disconnecting the detector with the transmitter and its tuning means, and a sparking device for the transmitter.

4. In wireless telegraph apparatus, means for tuning a transmitter to a distant sending station, said means comprising the combination of the transmitter, means for tuning the same, a detector responsive to current intensities, a capacity, means for connecting the capacity in parallel with the detector, means for connecting and disconnecting the detector with the transmitter and its tuning