I used to have an Ag Leader antenna (went bad) and now use a cheap Garmin for the combine.  The Garmin required a different cable and settings as mentioned above.

The back of my PF 3000 Pro has nine pin "Ports" numbered one through 4 along the bottom.  It also has fifteen pin "Aux 1" and "Aux 2" on the sides.  These are in addition to the larger port for the power supply. 

Both of my antennas plugged into the fifteen pin "Aux 1". 

Again, this was a "PF 3000 Pro".  Your PF 3000 could be different.