| 摘要 |
488,112. Wireless receiving systems. MARCONI'S WIRELESS TELEGRAPH CO., Ltd., and KEALL, O. E. Dec. 31, 1936, No. 35886. [Class 40 (v)] Relates to receivers employing automatic frequency control with an asymmetrical characteristic, i.e. to systems in which the automatic control action is different when the receiver is off tune in one direction from when it is off tune in the other direction, a relay being employed to change the connections to make manual tuning possible in either direction. According to the invention a condenser C is connected to a variable source of potential, such as a cell T and potentiometer P, the variable element of which is ganged with the tuning condenser of the receiver. The charging current of the condenser C, when the slider S is moved, operates a meter type relay R, the contacts RC of which reverse the excitation of the winding R1 of a polarized relay the contacts (not shown) of which effect the necessary changes. The meter type relay may be employed directly to change the connections ; and in a modification, Fig. 3 (not shown), coil R is replaced by a resistance, the voltage across which is applied to the grid of a valve in whose anode circuit the polarized relay is connected. |
