Railroad built in 1800's

I have a place to search soon. It is an old railroad built in the 1800's. My dad said they found an 1804 half penny there. I hope to do the same. Any tips or tricks that I can use? I have an old coinmaster d6000 and I think it will fit the bill quite nicely. It's a good machine. Nothing like today's machines, but it can definitely do the job well. Just want to make sure I find everything. Should I use Max or normal GEB? What does that do? What does the Tuner knob do? Everything else I understand.