GB344074A - Improvements in or relating to thermionic tube circuits - Google Patents

Abstract

344,074. Valve amplifying circuits. STANDARD TELEPHONES & CABLES, Ltd. and STRONG, C. E., Columbia House, Aldwych, London. Dec. 5, 1929, No.37310. [Class 40 (v).] In order to permit the use of a large number of valves in one stage in the amplification of shortwave oscillations, a plurality of push-pull pairs or groups are so arranged that each electrode is excited in phase opposition to the corresponding electrode in the adjacent push-pull pair or group. As shown in Fig. 3 for two push-pull pairs 1, 2 ; 3, 4 the tuned grid circuit comprises divided condensers C<1>, C<11> with their mid-points connected to the filaments, and symmetrically-placed coils ITS', ITS<1>1, ITS2, ITS<1>2 to which the input circuit coils ITP, ITP2 are coupled. The grids of valves 1, 2 are excited in phase opposition due to their symmetrical connection across condensers C<1>1 ; whilst the excitation of the grid of valve 3 is in phase opposition to that of the valve 1, due to the voltage node between the coils ITS1 and ITS\. The tuned plate circuit C<1>2, OTP1, OTP<1>1, C<11>2, OTP2, OTP12 functions in a similar manner. Output is taken from a coupled circuit OTS1, OTS2 ; or the output circuit is connected through condensers across a capacity inserted between the coils OTP2, OTP<1>2- Each valve 1 .. 4 may be replaced by several parallel-connected valves ; and inter-electrode capacities may be balanced by condensers B1, B4. In Fig. 6 the circuit is re-drawn omitting the filaments, and it is seen that the arrangement can be extended to form a chain of push-pull pairs 1, 2; 3, 4; 5, 6 ; 7, 8. The outer pair of lines with their cross condensers form the plate circuit, and the inner pair the grid circuit, whilst the central line is earthed. The system thus comprises an assemblage similar to artificial lines with standing waves, a pair of valves being connected at each voltage loop.