Note
QST, Aug 1978, p. 94.
QST, Jan 1980 p. 116.
QST, Apr 1981, p. 176.
The model 721 had tunable filtersfor both CW and SSB. Bandwidths on CW were 80, 110, 150, and 180 Hz with a center frequency of 750 Hz. On SSB, the active filter had a high-pass cut-off of 375 Hz and selectable low-pass cut-offs of 1.5, 2.0, and 2.5 kHz. The 721 also had an impulse noise limiter; $59.95, 1980. (1)