High-voltage regulator tubes for color television receivers

Abstract

With the advent of color television, it became very important to regulate the high-voltage supply in the receiver. This paper describes the RCA-6BD4-A and the RCA-6BK4 low-current beam triodes of the sharp cutoff type designed specifically for this purpose. Typical operation of the tubes is described, and the results of an analysis of the regulator circuit are given. When the 6BD4-A is used, the output of a regulated 20,000-volt supply does not drop more than 300 v as the load current is increased from 0 to 1 ma. For the same increase in load current, the output of a regulated 27,000-v supply does not drop more than 500 v. When the 6BK4 is used, the output of a regulated 25,000-v supply does not drop more than 500 v for a similar increase in load current. A feature of the regulator circuit is that variations in output voltage may be kept within plus or minus 1 per cent for input-voltage changes of plus or minus 10 per cent, or the compensation for input-voltage changes may be eliminated while the above compensation for load-current changes is maintained. The requirements of a high-voltage supply for use with the RCA color kinescopes are outlined, and the 5BD4-A and 6BK4 are shown to satisfy the desired specifications.