I was looking at doucmentation to hook up to a couple of different Yaesu radios. The FT60 handitalkie should connect to the boards without an issue, it uses one wire (and ground) to talk to the radio. The 857D mobile is a different beast. It has separate RxD and TxD lines. The open collector scheme looks valid still.

Rather than pursue a separate PCB, I added a jumper and a couple of passives to allow the board to work in either configuration. The USB interfaced board design has been modified to verify operation with both configurations. When that is working correctly, I will update schematics and update the other boards. The 3.5mm jacks that were used on these boards are stereo jacks. In the existing board design and the "2 wire" jumper configuration, the data in and out are on the tip of the plug and the ring is left unconnected. In the "3 wire" configuration on the new board, the tip is the TX data out and the ring is the RX data in. The body of the connector in all configurations is ground.

When the new boards come back from OSH Park and I can test them, I will post the new schematics. The existing schematics work fine for talking to any radio that only uses a single data wire.