Christy,

I have a Tmg-707a here and it works quite well.  I'm currently
using an inside antenna, a mag mount.  I can hear quite a few
machines on 440, but cannot bring up most of them even on high
power.  

There are also several on 2 meters which I can hear quite well but
also cannot bring up.  

Remember that those repeaters are usually in good locations for
both transmitting and receiving 
and they use good antennas.  So, they probably talk a bit better
than they hear.  Put that together with a smaller antenna on your
end, and you'll hear quite a bit that you can't talk back to.  And,
a lot of it will depend on what kind of an area you are in with
regard to mountains and such.  

So, don't get too frustrated if you can't talk back to everything
you can hear, especially if you're in a place where you really
can't get up a good antenna in the clear.  

Don  W6SMB