Linear Tracker ...I was wondering

CT, you are so right! Perhaps I was thinking Air Tangent, although I'm not certain as I've never seen one. But for some reason I forgot everything I ever knew about the ET design. Thanks for correcting my error - alas, all to common at my age.

But, we still have a cantilevered beam. The Trans-Fi is easy to fix with a support on the free end. The ET requires another bushing on the other side, which in turn means a great long massive bearing shaft between the two air bushings. I saw some Chinese audiophiles demo something of the sort, and I was about to build one when I discovered the Trans-Fi.

The big advantage of the Trans-Fi is how accurately one can set azimuth - a few minutes of arc - not that I can hear better than about 15 or so. I tried to engineer something as good, but it ended up mighty clunky. So I bought someone else's solution and modified it as above.

Maybe we should host a thread on linear trackers and their mods?

Actually,the best air bearing arm is the Walker. It had the lightest horizontal mass. The air bearing is stationary and large. It uses a lower pressure (less noise). The arm is made out of some type of very light composite. The turntable section is actually the original Air Force, air bearing platter, air bearing suspension etc.  https://walkeraudio.com/proscenium-black-diamond-v/
Unfortunately, Walker also sells a bunch of BS on their web site and I refuse to support that. I find it odd that the press has not compared the Black Diamond to the Air Force 1.

Surprised there is no mention of Advanced Analog MG1. An affordable linear tracking option. Their site is under construction. But there is info there.

adanalog.com

How accurately and repeatably can one set azimuth on the Walker? Looks like a simple collar-and-tube system, which is not really either. Do you know, Mijo? 

OP, have you noticed how the discussion has progressed to the point where we are now discussing the merits of the tonearm on a $150,000 table, or the legendary ET, compared to the Trans-Fi?