SM120 programming problem with 144.870 frequency

[ve7bz]

I am attempting to program a group of SM120's with an amateur repeater frequency of 144.870. Even using the left shift key trick, I am not able to enter the frequency. Each time I get an error message stating the frequency range of the radio is 145 to 180.

I understand it is possible to edit the sm50.mdf file to move the allowable frequency lower than 145 -- but I need help understanding the file format structure and what variables to edit.

Can someone help with file editing information or a possible work around to entering this lower frequency?

Paul