On Dale's website he talks about the Vacuum Tube design
http://www.trainfacts.com/trainfacts/?p=486
"UPDATE 5/8/13
I have built a booster amplifier based upon the vacuum tube design of Jim Lefevre, adding a few embellishments of my own. I hope to test the amp on some large layouts in the near future."
Dale posted the Vacuum Tube schematic on the OGR forum in May 2013.
Glenn