The information in the other article is incorrect. You don't even have to do ANY mod to the radio to make this work. Follow these instructions and you'll have no problem.
Press "F" until you hear beep and/or key icon (in upper right corner of display) disappear.
- Select your VHF freq. on the left side (in VFO or a memory channel)
- Select your UHF freq. on the right side (In VFO or memory channel, as well)
- Push AND Hold Both RIGHT and LEFT Band Knobs until you hear a BEEP
- WHILE STILL HOLDING KNOBS, Press the "F" button (between the right vol/sql knob and band knob) until it BEEPS and you see the "Skeleton Key" Icon Flash on the upper right side of the display
- Crossband is ready to use. You can not change freq. until deactivated.
Press "F" until you hear beep and/or key icon (in upper right corner of display) disappear.