Hi Ross,

I have a couple of mods that you may or may not have.  For the TH-75A MARS/CAP
mod, removing D4 will allow TX across entire tuning range, except that
actual TX range will be limited by tuning of the PLL.

For the TM-731A, there is a "Beyond MARS/CAP transmit Modification".  It
provides TX from 136 to 174 and 400 to 500 MHz.  Again, actual TX range limited
by PLL tuning.  If you don't already have this and would like it, I'll
send a copy if you furnish me your address.  It involves cutting R25 on the
control unit, and installing a jumper (diagram required to locate position),
then two resets in a row.

I have tested these mods on my own rigs.

73 - Kevin, KD2SL @ KC3BQ