I am trying to understand the operation of this Transmit Receive switch. I don't understand the explanation of operation provided in the attached instruction manual. The circuit consists of a cascode circuit. I would greatly appreciate someone being able to explain it to me like I am a kindergardner. I am not the brightest bulb when it comes to electronics but I have always wanted to learn.

 

Since you want to learn, let me post a couple of links that explain vacuum tube operation - http://www.vacuumtubes.net/How_Vacuum_Tubes_Work.htm

http://www.john-a-harper.com/tubes201/

http://en.wikipedia.org/wiki/Vacuum_tube