I have a Heathkit TT1A with all documentation, ie: assembly manual, operators manual, and the 1A manual. Also has approx. 6 extra supplement charts and Heathkit ordering cards. This tester calibrates perfect and works great. I also sell on e-bay under the handle fatwax for feedback research. I am looking for a pre-amp to match with a Threshold S-150 and will consider trades or offers. Email me at: legendarypinkdots@hotmail.com with offers. I can send photos of the unit. I live in British Columbia, Canada.