TAPR-2 and clones.  MFJ-1270, PAC-COMM TNC-2, etc.  The MFJ-1270B and
MFJ-1274 do not use this active filter.  Some AEA PK-80 TNC used soldered
in chips and the possible value of this modification will have to be made
before removing the mentioned parts.
The removal of the MF-10 chip and associated resistor network from TAPR-2
type TNC's can increase through put by reducing the ringing of MF-10 active
filter.  The addition of a .001 if it's place, not only reduces low frequency
noise problems such as A.C. HV lines,  but also phase shifts the sine wave
input to the XR-2211 decoder chip.  This phase shift reduces the effect of
distorted sine waves from improperly adjusted neighboring stations.

Remove parts from U-17 and U-18 as illustrated below

               RADIO DIN CONNECTOR
                  _____
         ________!_____!_____________________________________
        !
        ! Pin 8  ___________
        !       !          o/  U-17
        !       !___________\         COMPONENT SIDE OF BOARD
        !                     
        !      _____________  Pin 1
        !     !            o/  U-18
        !     !_____________\
        !
     Install the .001 Capacitor between U-17 Pin# 8  and U-18 Pin# 1.
A voltage value of 50 volts or greater will work,  but typical 1000 volt types
have a lead thickness large enough to just plug into the I.C. sockets
mentioned above.   (No soldering)  73'S  BOB,  NK8T @ NK8T