Radio broadcast .. (1922-30)

Record Details:

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502 Radio Broadcast BUZZER WIRE LOOSELY WRAPPED INSULATION NOT REMOVED TELEPHONE RECEIVERS CRYSTAL DETECTOR TESTING OUT THE CRYSTAL DETECTOR An ordinary buzzer is requisitioned by King Electron. This acts as a small radio transmitting set. Its transmitting antenna is a short length of wire attached to one binding post of the buzzer and brought near the receiving set. A dry battery and a push button in series with the buzzer complete this test transmitter. As it buzzes, the cat-whisker is adjusted until the signals are heard nicely, when the tester is shut off and the tuner is adjusted for distant radio waves. wires loosely, or it may be wrapped around the aerial wire. Usually it is sufficient just to bring the wire near the aerial or antenna. With the buzzer working, the crystal detector is adjusted until the signals are heard best. It does not pay to find the ultra-sensitive point, as it will be found that such a point will only last for a little while until a crash of static "burns" it up. When the detector has been adjusted for good average results with the buzzer, the buzzer is shut off, and any signals that are passing through the ether should be heard nicely. In all work with radio, it is a very good plan to start with something known, and then work for the more difficult and more sensitive results. The buzzer tester falls into the first class, as by its use the receiving set detector may be well adjusted, which indicates that the detector and the telephone receiver with the by-pass condenser are all working well. With continued practice, it may be possible to remove the buzzer to quite a distance from the receiving set and still get the test. Under these conditions it is certain that the receiving set is in the most sensitive condition. The action of the crystal detector is fundamental, as the action of the other detectors :s better understood from this viewpoint. So next month the much greater activity of King Electron in the Grid Leak-Detector connection with the vacuum tube will be taken up, together with the action of the Heterodyne.