Note
QST Jun 1938. ("XA" introduced)
QST, Apr 1946, p. 103. ("ASD" $115.00)
National restyled the NC-1OOX to create the 100A and 1OOXA. Changes included a new direct-reading dial, a tone control, and an S-meter to replace the "magic eye" indicator. The chassis inside the 11-tube receiver's new cabinet remained essentially the same as that of its predecessor, including moving-coil band switching.
References
National's Notes, QST, Mar 1940, p. 73.
A few notes on the NC-100, QST Aug 1941, p. 55.