Tom,

Don't know what it is about old dictiphone foot switches, but I use one as 
well.    It has a plate on it that says "Edison Company, East Orange, New 
Jersey" so that's pretty neat.

I never cared for vox, and use the foot switch 100% of the time for ssb. 
Yes, that extra jack on the Heil mic will take a 1/4 mono plug to connect a 
foot or hand switch.     If the switch you get is too small,  glue or screw 
it to a piece of plywood to keep it in place or you will spend too  much 
time playing footsie  with it as you  feel around under the desk trying to 
find it

73 Steve KW3A