1978 April QST p. 14 The State-Variable Filter June QST p. 30 The ABC Active Filter December QST p. 35 The Club Filter (cw af filter) 1979 January QST p. 42 The CW Filter-Limiter April QST p. 15 A Simple CW Audio Filter 1980 July QST p. 17 Active Filters September QST p. 29 What is a Filter? December QST p. 14 Modern Design of a CW Filter Using 88- and 44-mH Surplus Inductors 1981 October QST p. 38 Beating Rotten QRM - CW Filtering for the Beginner 1982 February QST p. 18 Build an Audio Filter with Pizazz 5 pages April QST p. 33 Concept and Construction of a CW Filter 4 pages and Enhancer 1983 April QST p. 32 A Dichotic Detector for CW 3 pages QST p. 35 An Electro-Acoustic CW Filter 4 pages QST p. 45 Understanding and Using Audio Filters 4 pages October QST p. 14 A Tunable CW Filter 3 pages 1984 March QST p. 19 Switched Capacitor Filters - An 7 pages Engineering Technology for Amateur Radio Use July QST p. 11 Digital Switched-Capacitor Filters - 5 pages A Practical Construction Project 1985 April QST p. 23 A High Performance CW Demodulator 5 pages 1986 February QST p. 15 A Simple Effective Receiving Aid 5 pages (Stereo audio filter) April QST p. 13 SuperSCAF and Son - a Pair of Swithed- 7 pages Capacitor Audio Filters December QST p. 32 Digital Signal Processing - A Modern 8 pages Audio Filter