Note
QST, Oct 1973, p. 150.
This appears to be MFJ's first ad and product.
CWF-2BX
Improved
QST, Sep 1974, p. 115.
QST, Aug 1975, p. 127.
QST, May 1976, p. 105.
QST, Feb 1977, p. 120.
QST, Nov 1980, p. 122.
Based on the provided document, here are the specifications for the – MFJ CWF-2– active audio CW filter:
Specifications
– Poles: 8 poles
– Selectable Bandwidths: 180 Hz, 110 Hz, and 80 Hz
– Center Frequency: Standard 750 Hz (optional 400 Hz or 1000 Hz)
– Skirt Selectivity / Rolloff: Ultra-steep skirts — 60 dB down 1 octave from center frequency (at 80 Hz bandwidth)
– Load Drive Capability: Can drive loads of – 500 ohms or greater– (e.g., high-impedance headphones) without distortion; can also drive lower impedances like 8-ohm headphones with an optional audio transformer (500:8 ohms) or by lowering the input signal level
– Input/Output Impedance: Designed with a very high input impedance (source driving the filter should ideally be less than one-tenth the input impedance)
– Components & Active Devices: Uses – 747 dual operational amplifiers
– Resistors and capacitors are hand-matched for precise center frequency alignment
Power Requirements:– Operates from – 6 to 30 VDC
(Cabinet version CWF-2BX uses a 9V battery)
