GB655247A - Improvements in or relating to high frequency electron discharge tube circuit arrangements - Google Patents

Abstract

655,247. Valve circuits. RADIO CORPORATION OF AMERICA. Oct. 14, 1946, No. 30587. Convention date, Oct. 16, 1945. [Classes 40 (v) and 40 (vi)] A two conductor transmission line is coupled to the grid and cathode of a valve by connecting one conductor directly to the cathode and the other through an inductor to the grid the value of the inductor being such that it is tuned by the input capacitance of the valve and the output capacitance of the line to the desired frequency. The Figure shows the frequency doubler and driver of a frequency modulated 78-104 Mc/s. transmitter. The F.M. carrier input is applied to a coaxial line 4 and then via inductor 10 and blocking capacitor 12 to the grid of frequency doubler valve 8. Inductor 10 serves to match. the output impedance of the line 2 to. the input impedance of valve 8 and also to cause the stray capacities 13, 14 which tune the inductor, to be effectively in series, thus reducing their effective value. Filter 15, 17 prevent the flow of R.F. currents through the grid leak resistor 26. A similar inductor 40 matches. the impedance of the doubler stage 8 to that of the driver stage 18, inductors 44, 46 acting as R.F. chokes and also effectively increases the capacitive reactance of the input circuit of valve 18. Inductor 40 is tuned by the stray capacitances 16, 20 of the circuit to the second harmonic of the input signal applied to valve. 8. Inductor 102 matches the driver stage 18 to a transmission line 114 which feeds the 'power output stage described in Specification 655,295, a variable capacitor 113 serving to adjust the load on stage 18. Capacitors 90 and 92 may be adjusted to series tune the connections of the screen grids to earth. The Specification as open to inspection under Sect. 91 also-includes the subject-matter of Specification 656,295.