A novel approach to a low cost, high-gain television intermediate frequency amplifier

A new tube, consisting of a dual control and a sharp cut-off pentode in the same envelope has been developed. Development of the tube, the Y-1187, makes possible a one-tube, two-stage, IF amplifier that attains the same performance level as most three-stage IF amplifiers that are used in black and white television receivers at considerably less cost. The input section of the Y-1187 is similar to the 6GK7, while the output section is similar to the 6DK6. The problem of interelectrode capacitances that results from placing two such high performance tubes in the same envelope is minimized by applying special shielding techniques within the tube. Experimental results indicate that the Y-1187 when operated as a two-stage IF amplifier, yields excellent gain, response, and AGC characteristics. Some of the primary features of the tube are: 1. Low-cost construction. 2. High-transconductance and low-capacitanee in each section 3. AGC applied to suppressor grid of the input section, which allows control grid bias to remain reasonably constant. 4. Additional gain obtained by the elimination of the need for unbypassed cathode resistors, and by the use of a quadrature-boost circuit. 5. Circuit costs and space requirements reduced by the elimination of one tube socket and a portion of the associated circuitry and circuit components. The writers wish to acknowledge the assistance of W.F. Cullen of the Tube Department, and W.P. Kimker, formerly of the Tube Department, without whom this paper could not have been prepared.