Subject: TH22AT KENWOOD HT MOD





Subject:  KENWOOD TH22AT extended frequency operation.



This procedure will expand the capabilities from 136.000 to 173.995 MHz.



PROCEDURE:



  1. Turn off power and remove battery pack.



  2. Remove antenna and two knobs from top of unit.



  3. Gently pry the rubber escutcheon off the top of the unit.



  4. Remove the two long screws from the rear of the radio case.



  5. Squeeze the bottom of the front panel together and gently separate

     the two case halves.  Use caution so as to not damage the thin

     ribbon cable connecting the front panel to the main unit.



  6. Remove diode D208 located on the circuit board behind the front

     panel.



  7. Place the diode just removed in the location shown for diode D212

     and solder in place.  Observe proper polarity.  The diode should

     face the same direction as diodes D210 and D211.



  8. Reverse steps 1-5 to reassemble.



  9. Reset the microprocessor.



  CAUTION: This modification requires soldering equipment rated for CMOS

  type circuits.  It also requires familiarity with surface mount soldering

  techniques.  If you do not have the proper equipment or knowledge do not

  attempt this modification yourself.  Seek qualified assistance.



                              PHYSICAL LOCATIONS





              !                           ========  W201

              !

   TOP        !                         ========  W202

              !

              !        __________________

              !        !                !         [D206]      [D210]

  -----------------------               !

                       !                !         [D207]      [D211]

                       !    CN203       !    

                       !                !         [D208]      (D212)

    thin ribbon        !                !  

                       !                !                     (D213)

                       !                !

  ------------------------              !

              !        !                !

              !        ------------------                ___________

              !                               __________!          !

              !_______________________________!__SPKR___!___MIC____!________



                        X57-4370-11  (B/4)



  ==========================================================================



  Most of this information was taken from a bulletin I received from KC7AOF.



  Several Mods have proven this alteration accurate and effective.