TNC2.1
          1 kohm    (1/4 watt, 5 or 10%)
          1.5 kohm       (ditto)
          7 inches of #30 wire-wrap wire
          2 each 1" pieces of insulated sleeving
 
(1)  Remove  the 470 ohm resistor R34 adjacent to the battery and  replace 
     with  the  1.5 kohm resistor.  Solder both ends,  but leave  the  end 
     nearest the battery a bit long for the moment.
 
(2)  Cut  the trace on the PCB between pins 11 and 12 of U14 (if you refer 
     to the TNC2 schematic #3, you will find that U14 has 3 unused gates - 
     this modification uses 2 of them).
 
(3)  Run  the  wire-wrap wire from U14 pin 11 to U7 pin 9.  I tacked  this 
     wire down several places along the board using dabs of  cyanoacrilate 
     "super glue" to keep it neat.
CONTINUED IN FILE TNC2.13