Charles1Dad, go to these links:
http://www.hans-egebo.dk/Tutorial/tubes.htm Go to "Tubes become active" section.
http://www.diyaudio.com/forums/tubes-valves/178688-triode-plate-resistance-internal-negative-feedback.html
http://www.hans-egebo.dk/Tutorial/tubes.htm Go to "Tubes become active" section.
http://www.diyaudio.com/forums/tubes-valves/178688-triode-plate-resistance-internal-negative-feedback.html