This kit was inspired by the inhibiting galactic noise encountered when listening to HF CW. Many proficient CW operators turn the AF gain full on and manage the audio signal and noise with internal rig filters and the RF gain knob. Even with these techniques band-limited cosmic static is present along with some man-made noise. There isnít much one can do to copy CW notes that are simply too weak; but, one can scrub away a portion of the static that makes its way into our consciousness with an audio regenerative filter. (See the feature article on the CW Scrubber in November, 2012 CQ Magazine.)
For example, when tuned to a quiet spot on 30-meters, regenís output shows a reduction in noise compared to the signal at the phone jack of the receiver. In bypass mode one simply listens to what the rig has to offer. In scrubber mode, the multiple-op-amp filters and regen work together to remove a majority of the remaining white noise. The processed signal sounds clean with a slight echo-chamber quality. For most this is an improvement, reducing stress and improving copy.
At the club meeting Rick, WA8UMT showed the "CW Scrubber" in and out of circuit with a weak CW signal on the 40 meter band. Rick used a Ten-Tec QRP transceiver and a vertical antenna.
More information can be found at: http://www.midnightscience.com/index.html
The kit with all the parts is $50 (the case is $20 extra)
CW Scrubber Inside
Rick's setup at the meeting.
Rick enjoying the "clean" code from the "Scrubber"