I'm thinking of initially using a J-Pole antenna for the UDRX, so want to construct it for the right part of the band. Has anyone thought about where in the 70cm band UDRX communications would best fit (both North and South of Line A) so as to not disrupt other licensed users of the spectrum?
The UDRX works from 430 to 450 MHz so line A isn't a problem. Bandwidth is less than 5% so you could just make it resonant at 440 and be done.
Here in Western Washington the Band Plan lists:
430.8000 - 431.0000 Packet radio
439.8000 - 439.9750 Packet Radio
440.7000 - 440.7750 Packet repeater outputs
440.8000 - 440.9000 Packet simplex
441.0000 National Packet simplex frequency
445.7000 - 445.7750 Packet repeater inputs
Which suggests centering at ~ 438
Of course if you choose to do D-STAR you could be pretty much on any analog voice channel or even one of the splinter channels between analog.
I wouldn't over think it too much,