Second source on tubes
Taylor, N. H.
In a letter dated 28 April 1954 from J. W. Forrester to C. McElwain, it was stated that certain tubes are important components in the FSQ-7 which should have a second source. Subsequent action led to a recommendation that a second source for each of these types be set up.
This note emphasizes two minimum requirements on any program if it is to meet over-all System requirements: interchangeability of tubes from the two sources and process and quality control at each source.