Just for information, Unless the TK250 has an (N) in the model number, it is a wide band only radio.
See Kenwoods compatibility list below. Yes,the 280 is not listed, but do google or check in software and it/they will show both.
Both the TK 280 and TK 290 are both wide and narrow.
Software for the 250 is DOS only (KPG23D) the 280 is KPG49D (WIN) and te 290 is KPG38D (WIN)
Send me your direct e-mail thru my PM if you need more help.