The Retarding-Field Tube as a Detector for Any Carrier Frequency

The rectifying effect of the retarding-field detector even at extremely high frequencies is due to the nonlinear retarding-field characteristic curve. The more detailed discussion of the retarding-field circuit as a "resistance transformer" shows the advantage of loading on the grid side. The extremely sensitive regulation of the retarding-field potential is avoided by high-resistance shunting of the retarding-field electrode. As excitation and rectification cannot be superposed in a retarding-field tube without interference, a receiver has been developed with two separate tubes, and this in turn led to the twin receiver. In the effort to apply the high-frequency voltages in a closed parallel wire system to the retarding electrode alone, a push-pull arrangement with a special tube was developed. In this tube the retarding electrode is divided into two segments. From this there was developed an exceedingly simple decimeter-wave receiver that is tuned only by means of the grid voltage. The high sensitivity of the retarding-field detector suggests its use for the rectification of any carrier frequencies, in which, nevertheless, the internal retarding resistance creates difficulties. By capacitative short-circuiting of the high-frequency current transfer perfect no-power control of the retarding-field detector, and consequently a sensitivity greater than that of all the other rectifiers, is obtained. At the same time the retarding-field detector can deliver a regulating voltage in a suitable phase for fading compensation.