from K4TWJ in March 91 CQ.
This keystroke mod will enable AM reception 119 to 138.
>press the ENT once or twice to get the rig in VFO mode and a 2 meter freq
on the display.
>next, press the F key for 2 seconds (note flashing F in display's
lower right)
>release the F key and press the MHz key.  The rig and desplay will
shift down into the 119 to 138 range.
>After finding and storing interesting freqs into memory, do
the previous F plus MHz keystrokes and the rig goes back to the 138 to
170 rx range.
*If your TH27a doesn't shift ranges, do a microprocessor reset.
>press and hold the M key and press the power switch ON.  The display
will flash and then come up on 144 MHz.  Now you should be able to
change ranges to receive.