I have finally successfully assembled two v2.2 headless attenuators and they work beautifully. Electrically they work exactly as designed and the vacuum has held steady for over a month.

There is work to do on this yet - I want to redesign the wooden base and the power supply box (central black box). The base and power supply box were designed for the v2.1 version of the attenuator that had a vacuum sensor in the power supply box along with vacuum hose between the power supply box and the attenuators. There was also a vacuum hose emanating from the rear of the power supply box to a ball valve. All of the external vacuum hoses have been eliminated in the v2.2 design by using sleeve valves and a vacuum sensor inside each vacuum chamber. This has greatly simplified and “cleaned-up” the design. A big improvement and one of many improvements between the v2.1 and v2.2 designs.

v2.2 Headless attenuators and associated remote.

Actually there are three attenuators because I also assembled two complete v2.2 attenuators with the motorized knobs but one of them has a slow vacuum leak that I am trying to troubleshoot. I will post pictures of the two complete v2.2 attenuators as soon as I solve the vacuum leak (soon I hope).