Hello,
I am new to the forum.  Searching for ideas found this thread.  Was it ever solved?  I am having the same issue described here.  Same Settings, double check the jumpers and straps but I am not getting any TX audio out.  I am able to key a local repeater but audio is not going out.  If I connect my mic directly to the radio it works perfectly.  Using an MD-100 mic.  
Thanks for any help with this. 
73's
Osvaldo
KP4OSP