LX4000 GPS Connections

I have friend that just purchased a PIK20 that has an LX4000
computer.

We are unable to get the LX4000 to pick up a GPS signal. The
documentation with it is confusing. Some of the documentation says it
has an internal GPS receiver and indicating all is required is to
connect a GPS antenna to the BNC connector on the back.

Other Documentation that he has says to wire a NEMA connection
directly into the BNC connector, indicating that a separate GPS is
required and in fact this appears to be how the LX4000 is currently
wired. (This seems very strange, can anyone confirm it is correct?)

We have unable to find a wiring diagram for the LX4000. Does anyone
know or have any documentation that would indicate the correct way get
the GPS to work on the LX4000.

Any information you can provide would be greatly appreciated.