One thing that old tube transmitters have over new solid-state designs is the lovely glowing tubes which are nearly always (in Continental designs, anyway) visible through a window on the front of the modulation cabinet. Look closely and note the dates marked on each tube envelope indicating when it was last replaced. (This is CJBC #2 again.)
Copyright 2004, Garrett Wollman. All rights reserved. Photograph taken 2004-09-02.