[GreenKeys] Model 28 Stuntbox fun and games

[Jim Haynes]

Prior to all that there was a method of operation called "bell break" 
which used bell for transmit-receive switching.  I guess that was chosen
because pre-Model 28 the bell mechanism was the easiest thing to attach
a switch to, to operate the circuit.  (And the sound of the bell reminded
you that your transmitter had been turned on.)

I guess those other things came into use when everybody had 28s and all
those extra stunt box contacts to play with.  Figs-blank-H was originally
the motor stop sequence.