Use the following procedure to create a split on the BK-5.
Note: Make sure that the SPLIT, LWR, and UP2 buttons aren't lit.
1. Press a TONE button so it lights to select a tone category for the right-hand side of the split.
2. Press the SPLIT button so it is lit.
3. Press the LWR button so it is lit.
4. Press a TONE button so it lights to select a tone category for the left-hand side of the split.