I searched far and wide and eventually found the pin-outs for the Furuno GT-77 GPS timing module. I believe the 16 Satellite, GT-80 timing GPS modules are the same pin-out. Pin1 is the closest pin to the antenna socket. 1. TXD 2. RXD 3. Ground 4. +5v 5. not specified. 6. 1PPS 7. Battery Backup Power 8. NC 9. NC -mark Vk2hmc