The more things change the more they stay the same a retrospective and prospective look at TWTs

Having left the TWT industry in the mid 1990´s after a 15 year career as a Vacuum Tube Engineer this paper looks back at what changes have occurred and where the industry is headed in the future. As technology continues to advance giving us smaller, faster and more powerful computers has the vacuum tube industry kept up or have we simply increased frequency and power levels without necessarily advancing the processes, materials and manufacturability of the devices?