DeForest 424 High Gain
AC Det/Amp Triode
1930

This 424 is labeled "Special High Gain" and also carries the Cunningham type marking of C229 on both the tube and the carton. According to an item in Radio Engineering magazine, DeForest developed a special high gain version of the 424 for use in midget receivers with minimal tube count. This tube had double the voltage gain of a regular 424 and was interchangeable with it. The significance of the C229 marking is not known.