The following is a simple modification for the TM-221 rig:
1- Locate the control unit board (X53-3040-XX)
located behind the front panel.
2- Right below the channel select rotary switch and opposite the M.IN
Sw. you will find R24 and R25.(foil side)
3- Remove R25 for 142.00 thru 151.995 Mhz RX TX
4- Move R25 to space for R24 for 138.00 thru 154.000 Mhz TX RX
(Range will vary slightly from set to set)
Info provided by N2EYR @ WA2SNA-1 / Eddy Salvador