QST, Apr 1980, p. 176.
QST, Apr 1981, p. 193.
QST, Jan 1982 p. 182.
The Model 645 Ultramatic was a dual-paddle electronic keyer. The torque-drive paddles had four ball-bearing pivots and were adjustable for travel and magnetic return. The 645 used transistor keying and had a speed range of 6–50 wpm.
