Note
QST, Dec 1966, pp. 106–107.
And see QST, Oct 1967, p. 121 for a list of Henry's commercial, industrial, and VHF amplifiers.
The 2K-4 linear used the same 3-500Z final tubes as the 2K-3 but received a style makeover in the form of a tilted RF deck atop the floor console. The meter style also changed, but most internal and performance features remained the same.