Note
QST, Feb 1976, p. 127.
QST, Apr 1978, pp. 86–87. More details.
QST, Jan 1980, p. 7.
QST, Mar 1981, p. 1.
QST, Jan 1982, p. 160.
HAL’s ST-6000 RTTY demodulator copied standard shifts of 850, 425, and 170 Hz. A monitor scope made tuning fast and accurate. The ST-6000 had active filters,a crystal-controlled tone keyer, and an internal loop supply.
