| 摘要 |
633,875. Superheterodyne circuits. PHILIPS LAMPS, Ltd. April 24, 1947, No. 10977. Convention date, Nov. 3, 1944. [Class 40 (v)] In a frequency-changing circuit employing a diode mixer, the damping of the input circuit is reduced and the signal-to-noise ratio improved by means of a triode reaction valve 9, Fig. 2. The grid of the triode may constitute the mixing diode (Fig. 3, not shown). The Specification as open to inspection under Sect. 91 comprises also an arrangement in which the damping is reduced by the use of a diode having a transit time such that the input impedance is negative (Fig. 1, not shown). This subject-matter does not appear in the Specification as accepted. |
