The following is a close up of the modifications made to the GE Master was made by W4UWH. The numbers on the Back panel are the DB 9 numbers on the right, and I do not use Pins 1 or 2. I sometimes use pin 4 for power control, it requires the addition of a reed relay and pot. I use the Computer Automated Technology (CAT) Output 1 to close the relay to switch between two power settings.
The following diagram show the connection of a CAT 1000 to the repeater and Doug Hall's RBI-1 Remote Base Interface.
I used a different Pin for Pin 4