The Kenwood TM201B transceiver has an option of adding a tone board TU-3. The module is hard to find and expensive. After doing a lot of digging, a Kenwood engineer helped me with the TU-3 Datasheet.
Below is the schematic in PNG format. This is also available at github.
I have published the code on github under Attribution-NonCommercial-ShareAlike 4.0 International License.