Note
QST, Feb 1956, p. 142.
CQ, Dec 1956, p. 111. (400-B)
QST, Jan 1958, p. 155.
Improvements in the 400-B include simplified operation, improved TVI suppression, and a new metering circuit to read RF voltage input and RF amperes output.
QST, Oct 1958, p. 118. (400-C)
CQ, Jul 1960, p. 123.
CQ, Nov 1960, p. 172. (New modern styling? Now 800 watts PEP) -- is that actually more than before? Or just PEP instead of DC?.
QST, Jun 1960, p. 155. (same info as above)
QST, Mar 1962, p. 147.
QST, Oct 1965, p. 169. (kit form)
