Note
QST, Aug 1973, p. 160.
QST, Apr 1974, p. 152.
QST, Jul 1975, p. 168.
QST, Oct 1975, p. 168.
Several versions available (DE-102, DE-103 and "A" versions of these) for phones only, phones and speaker, and 120 VAC or 12 VDC operation. DE-101 appaers to have been deleted as of QST, Oct 1975, p. 168.