Note
QST, Aug 1961, p. 2.
QST, Jun 1963, p. 161. (75S-3A)
QST, Mar 1964, p. 2. (75S-3B - "what's new?")
QST, Jan 1965, p. 140. (75S-3B)
QST, Feb 1966, p. 2. (75S-3B)
QST, Apr 1967, p. 2. (75S-3B)
QST, Feb 1968, p. 2. (75S-3B)
QST, Oct 1970, p. 2. (75S-3B)
QST, Sep 1971, p. 2. (75S-3B)
QST, Nov 1972, p. 2. (75S-3B)
QST, Apr 1975, p. 2. (75S-3C - first reference in QST advertising)
Collins product catalog, 16M-CR-12-74
QST, May 1976, p. 2. (75S-3C)
QST, Feb 1977, p. 117. (75S-3C)