Hi,

This conversation is reminding me of a couple things with military transmitters. 

TBX(0-6) and TCS both have limited keying rates in crystal control because of chirp.  In MO mode you can key faster.

I can't recall the name for the type of one-tube transmitter in the TBX with the 837 tube where the feedback of the oscillator is derived from one of the screen grids,   Maybe electron-coupled oscillator? 

RF