The Xtal Set Society offers a number of kits, aimed mostly at those wanting to experiment with shortwave reception using crystal and simple 1-transistor receivers. Also in the mix are a few pieces of simple test equipment like attenuators and dummy loads.
Their ad in CQ Magazine caught my eye some time ago and I finally got around to checking it out.
The ad mentions the CW Scrubber Kit that “scrubs away galactic noise”, resulting in clearer CW tones in the headphones. On their website the kit is called a CW Regen Filter (scroll a bit over halfway down) and costs $50 without a case ($70 with case).
My initial impression is that it’s way over-priced for what it is.
I can’t find any reviews online and I wonder if any are in the works – I’d love to read one that would change my mind.