Butch:

Yep, with the help of several others on the list, I set the VFO being used
for the 446.850 receive frequency to have a positive offset.  That means the
radio will not let me transmit there, since it is out of band, which gives
me the error beep I want, and also prevents unwanted transmissions on the
440 receive freq..

Was almost too simple of a solution, but hey, it worked!

Best 73 from Tom Behler:  KB8TYJ