GB403070A - Improvements in stabilising the frequency of a valve generator - Google Patents

Abstract

403,070. Valve circuits. MOULLIN, E. B., 189, Morrell Avenue, Oxford. April 12, 1932, No. 10434. [Classes 40 (iii) and 40 (v).] Relates to a tuning-circuit for use in a dynatron or other valve oscillator, in which, in order to prevent the frequency from being affected by the curvature of the valve characteristic, acceptor circuits LC2, LC3 .... are tuned to the harmonics, and an inductance L in branch a forms, with the capacity C1 together with the capacities in the acceptor circuits, a rejector circuit tuned to the fundamental ; and consists in equalizing the power factors of the inductive and capacitative branches of the total circuit at the fundamental frequency by addition of a resistance P. In order that the fundamental resonance may occur when P<2>LK=1, where K=C1+C2+C3 .... , the power factor of the inductance branch a must be equal to that of the remaining branches, which are capacitative at the fundamental frequency ; and to this end a resistance P equal to 0.868 R is added as shown, where R is the resistance in each inductance coil. The values of C1, C2, C3 ... are determined by the frequencies of the fundamental and harmonics with which they are associated, and C1=K- 2.3077 ; but as an approximation the inductances belonging to the high harmonics may be reduced to permit of the use of larger condensers. The inductance in branch LC2 may be shunted by a small condenser to make that branch capacitative to the fourth and higher harmonics.