Trying to manually program the Nebraska NWIN P25/VHF system in a 796D, When I enter the band plan information for the system space frequency I cannot enter 2.5 khz. It appears the the smallest frequency spacing I can enter is 12.5 khz. Even 6.25 khz does not work. I can enter the base freq and offset without any problems. Is this normal for this model or is there a firmwarm upgrade available?