Digi-mode interface for Yaesu FT-897D

I have finished a new interface for my FT-897D which I want to use mainly for VHF contacts using meteor scatter (MS) as the propagation mode. I made this interface very simple. I used two audio transformers 1:1 (600:600 Ohm isolation transformers), one optocoupler (CNY17-1) for PTT and USB to RS232 converter cable (PL2303 Chipset).